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The weak AC grid in a modular multilevel converter modular multilevel converter based high voltage direct current (MMC‐HVDC) receiving‐end system requires faster reactive power support from the receiving‐end MMC. However, under the MMC traditional constant AC voltage dual‐loop control strategy, the increase in MMC's reactive power support speed will reduce the system stability. The reactive power cascade control strategy is a novel MMC control strategy. The analysis in this paper demonstrates that it possesses advanced performance under faster reactive power support, which is required by the MMC connected to a weak AC grid, but, some of its control links and operations can cause impacts exceeding that a weak AC grid can undertake. To solve this problem, based on the original control strategy, this paper proposes an improved reactive power cascade control strategy for weak AC grid conditions. The complete framework and the detailed design of primary control links of the improved cascade control strategy are displayed in this paper. Finally, a digital simulation has been conducted to validate the analysis and the proposed improved control strategy in this paper. [ABSTRACT FROM AUTHOR]

This paper presents a novel hybrid type-2 fuzzy sliding mode control approach for regulating active and reactive power exchanged with the utility grid by a doubly-fed induction generator in a wind energy conversion system. The main objective of this hybridization is to eliminate the steady-state chattering phenomenon inherent in sliding mode control while improving the transient delays caused by type-2 fuzzy controllers. In addition, the proposed control approach has proven to be successful in coping with varying generator parameters and exhibited good reference tracking. An in-depth comparative study with state-of-the-art advanced control techniques is also the focus of the present paper. The comparative study has three objectives, namely: a qualitative comparative study that aims to compare response times and reference tracking capabilities; a quantitative evaluation that takes into account time-integrated performance criteria; and finally, robustness capabilities. The simulation results, carried out in the Matlab/Simulink environment, have demonstrated the effectiveness and best performance of the proposed hybrid type-2 fuzzy sliding mode control with respect to other advanced techniques included in the comparison study. [ABSTRACT FROM AUTHOR]

This paper introduces fractional-order capacitors and fractional-order inductors into the conventional integer-order cascaded H-bridge multilevel static compensator (ICHM-STATCOM), thereby constructing the main circuit of the fractional-order cascaded H-bridge multilevel static compensator (FCHM-STATCOM). Mechanism-based modeling is employed to establish switching function models and low-frequency dynamic models for the FCHM-STATCOM in the three-phase stationary coordinate system (a-b-c). Subsequently, fractional-order rotating coordinate transformation is introduced to establish the mathematical model of the FCHM-STATCOM in the synchronous rotating coordinate system (d-q). Additionally, a fractional-order proportional-integral (FOPI)-based fractional-order dual closed-loop current decoupling control strategy is proposed. Finally, this paper validates the correctness of the established mathematical models through digital simulation. Moreover, the simulation results demonstrate that by appropriately selecting the order of fractional-order capacitors and fractional-order inductors, the FCHM-STATCOM exhibits superior dynamic and static characteristics compared to the conventional ICHM-STATCOM, and the FCHM-STATCOM provides a more flexible reactive power compensation solution for power systems. [ABSTRACT FROM AUTHOR]

Medium-voltage (MV) distribution networks that are spread through larger territory and threatened by extreme weather conditions are sometimes formed by very long underground cable lines. In such circumstances, a significant amount of capacitive reactive power flow can be generated. If, concurrently, there is low power demand in the network, it can result in significant reverse reactive power flows and voltage rise issues. This paper proposes a general approach for analyzing and mitigating voltage rise issues and demonstrates it using an example of a real distribution network that operates under the described conditions. Previous studies that dealt with this problem did not include the allocation of multiple shunt reactors in a larger distribution network, modeling a high number of lines that create reverse reactive power flows, and modeling the main distribution transformers, which are the locations where voltage rise predominantly occurs. In this paper, we demonstrate that precise allocation and placement of multiple shunt reactors in a fully modeled, larger distribution system, including transformer models, can reduce reverse reactive power flows, thereby improving voltage in the distribution system. If hourly control of the power factor from the distributed generation unit is also implemented, the voltage can be further improved. [ABSTRACT FROM AUTHOR]

This paper proposes a single-phase, transformer-less, seven-level inverter that utilizes eight switches, three capacitors, and two diodes to produce seven voltage levels with triple boosting ability. The availability of the common-ground point eliminates the leakage current in PV applications. The proposed Transformer-Less Triple-Boosting Seven-Level Inverter (TLTB7LI) has the ability to feed different types of loads from non-unity to unity power factors. The voltage balancing of capacitors takes place naturally without the need for auxiliary circuits and complicated control strategies. This paper investigates the appropriateness of the proposed TLTB7LI for grid-connected application. The Peak Current Controller (PCC) is employed to generate the switching pulses and regulate the active/reactive power transfer between the converter and the output, which guarantees the high quality of injected current to the output. Moreover, the operational principles, its control technique, as well as the design procedure of the key components of the proposed inverter have been presented. The superiority of the proposed inverter over existing counterparts has been verified through comparative analysis. The simulation and experimental analysis validated the proper operation of the proposed TLTB7LI. [ABSTRACT FROM AUTHOR]

This paper presents a groundbreaking control strategy for a bidirectional battery charger that allows power to be injected into the smart grid while simultaneously compensating for the grid's reactive power using an electric vehicle battery. An artificial neural network (ANN) controller is utilized for precise design to ensure optimal performance with minimal error. The ANN technique is applied to generate sinusoidal pulse width modulation (SPWM) for a bidirectional AC–DC inverter, with the entire algorithm simulated in MATLAB Simulink.The core innovation of this study is the creation of the ANN algorithm, which supports grid compensation using electric vehicle batteries, an approach termed "vehicle-for-grid". Additionally, the paper details the PCB circuit design of the system controlled by the DSP F28379D board, which was tested on a three-phase motor. The total harmonic distortion (THD) of the proposed ANN algorithm is approximately 1.85 % , compared to the MPC algorithm's THD of about 2.85 % . This indicates that the proposed algorithm is more effective in terms of the quality of the power injected into the grid. Furthermore, it demonstrates effective grid compensation, with the reactive power effectively neutralized to 0 KVAR in the vehicle-for-grid mode. [ABSTRACT FROM AUTHOR]

The increasingly extensive use of non-linear loads, mostly including static power converters, in large industry, commercial, and domestic applications, as well as the spread of renewable energy sources in distribution-generated units, make the use of the most efficient power quality improvement systems a current concern. The use of active power filters proved to be the most advanced solution with the best compensation performance for harmonics, reactive power, and load unbalance. Thus, issues related to improving the power quality through active power filters are very topical and addressed by many researchers. This paper presents a topical review on the shunt active power filters in three-phase, three-wire systems. The power circuit and configurations of shunt active filtering systems are considered, including the multilevel topologies and use of advanced power semiconductor devices with lower switching losses and higher switching frequencies. Several compensation strategies, reference current generation methods, current control techniques, and DC-voltage control are pointed out and discussed. The direct power control method is also discussed. New advanced control methods that have better performance than conventional ones and gained attention in the recent literature are highlighted. The current state of renewable energy sources integration with shunt active power filters is analyzed. Concerns regarding the optimum placement and sizing of the active power filters in a given power network to reduce the investment costs are also presented. Trends and future developments are discussed at the end of this paper. For a rigorous substantiation, more than 250 publications on this topic, most of them very recent, constitute the basis of bibliographic references and can assist readers who are interested to explore the subject in greater detail. [ABSTRACT FROM AUTHOR]

This paper attempts to provide a clear explanation of how the concept of double frequency complex plane is applied to the calculation of complex electrical power. This is a step to remove the confusion associated with the calculation of complex electrical power that has persisted in the scientific community to this day. It starts with a discussion on the conventional method of calculation of complex power and its relation with the Steinmetz’s original method of power calculation in steady state AC circuit. An excerpt from the writing of Steinmetz is then included in which he enumerated mathematical equations that were used to make adjustments while calculating two times the supply frequency complex electrical power from the supply frequency complex voltage and current. Since the equations appear to contradict the laws of conventional complex algebra, considerable confusion arose soon after the Steinmetz’s publication. This confusion persists even today. Usual text books do not touch upon this issue and merely describe the mathematical equation required for calculation of complex power. This paper tries to provide a justification behind the adjustment equations involving double frequency complex plane used for complex power calculation through a simple R-L circuit and provide analytical explanation of the equations enumerated by Steinmetz. [ABSTRACT FROM AUTHOR]

The increasing integration of distributed energy resources such as photovoltaic (PV) systems into distribution networks introduces intermittent and variable power, leading to high voltage fluctuations. High PV integration can also result in increased terminal voltage of the network during periods of high PV generation and low load consumption. These problems can be solved by optimal utilization of the reactive power capability of a smart inverter. However, solving the optimization problem using a detailed mathematical model of the distribution network may be time-consuming. Due to this, the optimization process may not be fast enough to incorporate this rapid fluctuation when implemented in real-time optimization. To address these issues, this paper proposes a co-simulation-based optimization approach for optimal reactive power control in smart inverters. By utilizing co-simulation, the need for detailed mathematical modeling of the power flow equation of the distribution network in the optimization model is eliminated, thereby enabling faster optimization. This paper compares three optimization algorithms (improved harmony search, simplicial homology global optimization, and differential evolution) using models developed in OpenDSS and DigSilent PowerFactory. The results demonstrate the suitability of the proposed co-simulation-based optimization for obtaining optimal setpoints for reactive power control, minimizing total power loss in distribution networks with high PV integration. This research paper contributes to efficient and practical solutions for modeling optimal control problems in future distribution networks. [ABSTRACT FROM AUTHOR]

The escalating worldwide power demand necessitates innovative solutions to address the emerging power crisis. Grid-synchronized electric vehicles (EVs) have emerged as a promising avenue for mitigating this crisis. The vehicle-to-grid technology is unique advanced smart grid concept by which the exchange of energy is allowed among grid and EV. The integration of EV and grid affects an entire power system causing imbalance in supply–demand, voltage and frequency. To minimize these issues, feasible optimization techniques are introduced in this paper. Lithium-ion batteries are initially charged via smart homes, and convolutional neural networks (CNN) are used to ascertain a battery's state of charge (SOC). A bidirectional SEPIC–zeta converter is employed in this paper by which voltage is either increased or decreased. The gating sequence for the converter is generated by means of adaptive neuro fuzzy inference system which depends on an estimated SOC. If the SOC is greater than 80%, battery is discharged using a SEPIC mode; if the SOC is lower than 80%, battery is charged by grid using the ZETA mode. By using a PI controller, active and reactive power are also controlled. Simulation results using MATLAB showcase the efficacy of the suggested approach. The bidirectional SEPIC–Zeta converter exhibits an impressive efficiency of 96% and a voltage gain ratio of 1:8 when compared to other converters. CNN-based SOC tracking achieves remarkable tracking efficiency of 92.3%, outperforming other tracking methods. The grid current total harmonic distortion is notably curtailed at 2.3%, and a power factor of 0.9 is achieved using PI-based grid synchronization. [ABSTRACT FROM AUTHOR]

This paper presents the control strategies and performance analysis of doubly fed induction generator (DFIG) for grid-connected wind energy conversion system (WECS). The wind power produces environmentally sustainable electricity and helps to meet national energy demand as the amounts of non-renewable resources are declining. The development of the WECS can be seen with development in power electronics technology. Currently, two types of major generator used in WECS these are DFIG and the permanent magnet synchronous generator (PMSG). Both variable oprational speed are used in wind turbine. Because its high performance, reliability, controllability and high-power and voltage capabilities, multilevel converters have become a popular option for multi-MW WECSs. This paper focuses on the application of back-to-back modular multilevel converters in a DFIG and PMSG-based WECS. A comparative performance analysis of the two systems based on power quality, active, reactive power, and modular multilevel converter dynamics is presented. The comparison is based on simulation results created in MATLAB/Simulink software. [ABSTRACT FROM AUTHOR]

Due to a rising share of renewable energy sources on the production side and electrification of transport and heating on the consumption side, the efficient management of flexibility in distribution networks is crucial for ensuring optimal operation and utilization of resources. Nowadays, the sensitivity-based approach is mainly used in medium-voltage (MV) networks for regulating voltage profiles with reactive power of distributed energy resources (DER). The main disadvantage of the simplified sensitivity-based method is its inaccuracy in case of a high deviation of the network voltage from the nominal values. Furthermore, it was also noted that despite the fact that the method is well described in the literature, there is a lack of systematic approach to its implementation in real-life applications. Thus, the main objective of this paper is to address this disadvantage and to propose an algorithm designed to calculate required consumer flexibility in near real-time to ensure distribution grid operation within operational criteria. In the first part of the paper, network state, including line loading and node voltages, is assessed to determine distribution network node capacity. By analyzing the sensitivity of network busbars to changes in consumption and production, our algorithm effectively identifies the most efficient nodes and facilitates strategic decision-making for resource allocation. We demonstrate the effectiveness of our approach through simulations of real-world distribution network data, highlighting its ability to enhance network flexibility and improve resource utilization. Leveraging sensitivity coefficients, the algorithm enables flexible consumption and production management across various scenarios, supporting the transition to a more dynamic and efficient power system. [ABSTRACT FROM AUTHOR]

Recently, there has been a significant increase in the integration of distributed energy resources (DERs) such as small-scale photovoltaic systems and wind turbines in power distribution systems. When the aggregated outputs of DERs are combined, excessive reverse current may occur in distribution lines, leading to overvoltage issues and exceeding thermal limits of the distribution lines. To address these issues, it is necessary to limit the output of DERs to a certain level, which results in constraining the hosting capacity of DERs in the distribution system. In this paper, coordination control methodologies of DERs are developed and executed to mitigate the overvoltage and overcurrent induced by DERs, thereby increasing the hosting capacity for DERs of the distribution system. This paper proposes three coordinated approaches of active and reactive power control of DERs, namely Var Precedence, Watt Precedence, and Integrated Watt and Var Control. The Var and Watt Precedence prioritizes reactive power for voltage (Q–V) and active power for current (P–I) to address network congestion, thereby enhancing hosting capacity. Conversely, the Integrated Var and Watt Precedence propose a novel algorithm that combines four control indices (Q–V, P–V, Q–I, and P–I) to solve network problems while maximizing hosting capacity. The three proposed methods are based on the sensitivity analysis of voltage and current to the active and reactive power outputs at the DER installation locations on the distribution lines, aiming to minimize DER active power curtailment. Each sensitivity is derived from linearized power equations at the operating points of the distribution system. To minimize the computation burden of iterative computation, each proposed method decouples active and reactive power and proceeds with sequential control in its own unique way, iteratively determining the precise output control of distributed power sources to reduce linearization errors. The three proposed algorithms are verified via case studies, evaluating their performance compared to conventional approaches. The case studies exhibit superior control effectiveness of the proposed DER power control methods compared to conventional methods when issues such as overvoltage and overcurrent occur simultaneously in the distribution line so that the DER hosting capacity of the system can be improved. [ABSTRACT FROM AUTHOR]

This paper gives an overview of the operating characteristics of the railway interline power flow controller (RIPFC) regarding the capability of transferring active power between two sections of an electrified railway line separated by a neutral zone and proposes its use for compensating the power factor at the substation instead of regulating the voltage level at the neutral zone. The basic analysis is based on simplified steady-state models for the energy supply architecture, while detailed time-domain simulations are used for more realistic tests. The paper mainly focus on active power balancing between two neighbouring substations and the global losses in the system. Other functionalities of the RIPFC system are also analysed, like reactive power compensation at the substations. The paper presents the main operating principles of the system, shows results for some representative scenarios (generic and reduced) and discusses the results. The most relevant conclusions are related to substation active power balancing and peak shaving, power factor compensation in the substation, voltage stability at the neutral zone and system power losses. [ABSTRACT FROM AUTHOR]

During the operation of the ITER machine, hundreds of MW/Var of active and reactive power will be exchanged with the grid. The E‐STATCOM scheme composed of the Modular Multilevel Converter (MMC) and split supercapacitor energy storage has been proposed to improve the power compensation performance of the existing reactive power compensation system in the previous study. However, one of the main technical challenges which is lack of research is to precharge all submodule capacitors and supercapacitors from zero to their nominal voltage values efficiently during a startup process. As the capacitance and operating voltage of supercapacitors are much different from capacitors in each submodule, the startup of E‐STATCOM is a more complicated process. To coordinate the energy exchange between submodule capacitors and supercapacitors, submodule capacitors and the grid, this paper presents an optimized four‐stage AC side startup strategy for the E‐STATCOM. The proposed method minimizes the use of current‐limiting resistors while suppressing the surge current in the zero‐voltage startup process of supercapacitors, in addition to optimizing the energy consumption. The pulse current charging, constant current charging and constant power charging strategies of supercapacitors are adopted in different charging stages, and the detailed coordinated control scheme between submodule capacitors and supercapacitors are described and analyzed. The effectiveness and performance of the proposed method are verified by simulation results and hardware‐in‐the‐loop (HIL) experiments. [ABSTRACT FROM AUTHOR]

The high uncertainty of wind power output greatly affects the rapid reactive power optimization of power systems. This paper proposes a neural network‐based comprehensive reactive power optimization method for large‐scale wind power grids, effectively addressing the challenges of rapid reactive power optimization in power systems. Firstly, by constructing typical wind‐power‐load scenarios, the generalization ability of the neural network is improved. Then, focusing on the comprehensive reactive power optimization problem after integrating typical wind‐power‐load scenarios into the system, the improved Harris hawks optimization algorithm (HHO) is compared with the particle swarm optimization algorithm and traditional HHO algorithm, highlighting its advantages. Finally, HHO is utilized for solving, thereby constructing a comprehensive reactive power optimization strategy tag set. Furthermore, through deep fitting of the neural network between the power grid operating state and the comprehensive reactive power optimization strategy, the computational complexity and decision‐making time of reactive power optimization are reduced. [ABSTRACT FROM AUTHOR]

In building a smarter and more flexible low‐carbon smart grid system, alternating current (AC) microgrids using virtual synchronous generator (VSG) technology are viewed as a key link in integrating distributed renewable energy access into the main grid. Given that renewable energy sources (such as solar, hydroenergy, and wind) do not have sufficient capacity for reactive power when not available, AC microgrids face challenges in maintaining stable operation. In order to overcome this difficulty, it is hoped that digging deeper and applying more system information can significantly improve the overall performance of the microgrid. This paper proposes a novel method based on macroscopic state dynamic modeling. This method expands the understanding of the inherent rational control mechanism within the microgrid, enabling the overall control objective of the microgrid to be expressed in a more abstract and direct manner. Additionally, by implementing additional convergence constraint conditions on the macroscopic state dynamics, such as based on some optimality criteria, a set of macroscopic state controllers can be obtained to meet specific performance indicators. Theoretical analysis combined with simulation validation demonstrate the effectiveness of this macroscopic state based control strategy. It proves that when meeting the predefined design requirements, the designed controller can enhance the transient response of microgrids in practical applications, thus supporting higher rate of renewable energy access and promoting the development of the smart grid. [ABSTRACT FROM AUTHOR]

Industrial applications tend to involve a substantial assemblage of electronic devices, and it is imperative to consider diverse charging requirements while charging these devices. This paper proposes a three‐coil single‐input‐and‐dual‐output (SIDO) inductive power transfer (IPT) system to meet the charging requirements of different devices. The system includes two independent output ports, providing constant voltage (CV) output and constant current (CC) output for different loads, respectively. In addition, the zero‐phase angle (ZPA) operation can be achieved, thus avoiding injection of reactive power and improving energy transfer efficiency. Unlike previous related studies, the receiver of the proposed SIDO IPT system only includes one receiving coil to pick up energy, eliminating unnecessary cross‐coupling and complex decoupling circuits in traditional IPT systems with multiple outputs. This study first analyzes the CC/CV output theory of the proposed SIDO IPT system in detail, and designs and optimizes the parameters by establishing an equivalent model. Then, the conditions for achieving zero‐voltage switching (ZVS) operation of the inverter are obtained by analyzing the sensitivity of CC/CV performance to the variation of the compensation capacitors. Finally, a verification experimental prototype with 2.5A CC output and 72 V CV output is established to verify the effectiveness of the proposed IPT system. [ABSTRACT FROM AUTHOR]

In the multi‐paralleled converter microgrid system, the traditional hierarchical control strategy can eliminate the bus voltage amplitude and frequency deviation from the rated value. However, isolated AC microgrids may face extreme scenarios such as communication delays and interruptions in data transmission due to the use of low‐bandwidth communication (LBC) lines. Additionally, the inconsistent line impedance of each distributed generation (DG) unit may result in the inaccurate division of reactive power in multi‐paralleled converter systems, thus affecting system stability. To address these issues, this paper presents a distributed coordinated control strategy for isolated AC microgrids based on the consensus algorithm. The proposed strategy first replaces LBC lines with a filter to alleviate the effects of communication delays. A small‐signal model is established in its state space, and stability of the microgrid system under the proposed control strategy is verified through eigenvalue analysis. Furthermore, based on the above theoretical analysis, a consensus algorithm is introduced, and a distributed control strategy for isolated AC microgrids based on the consensus algorithm is proposed to solve the issue of inaccurate equalization of the system's reactive power. Finally, factors that influence the dynamic convergence performance of the consensus algorithm are analyzed through simulation in PLECS software. Also, the maximum tolerable communication delays of the microgrid system under different communication topologies are also compared, and the system's robustness is evaluated under the condition of sudden communication interruption in a DG unit and sudden weather variation. These analyses confirmed the robustness of the proposed strategy against communication delays, output power fluctuation, and communication interruptions. [ABSTRACT FROM AUTHOR]

This paper presents various control strategies to improve operations in two interconnected areas connected by a VSC‐HVDC transmission line. The main focus is on designing a central control system (CCS) that coordinates control units in both areas. In area 1, an AC voltage control unit is connected to the CCS. In area 2, three control units including a load power control unit, a fault detection unit, and an AC voltage control unit are also connected to the CCS. The CCS receives inputs from these units and generates commands for the DC voltage and active/reactive power control units on both sides of the DC line. The first proposed strategy addresses permanent voltage drops caused by load fluctuations in area 2. It adjusts the transmitted power from area 1 based on voltage variations in area 2. The second strategy focuses on mitigating faults in area 2 by injecting active and reactive power from area 1 during such events. The third strategy resolves transient voltage oscillations in both areas by controlling the reactive power of stations on either side of the DC line. Simulations using MATLAB‐SIMULINK demonstrate that these mechanisms successfully achieve their objectives. [ABSTRACT FROM AUTHOR]

Summary: The d‐q detection method based on instantaneous reactive power theory (IRPT) is one of the commonly used time‐domain analysis methods for harmonic detection. Due to the poor dynamic performance of the algorithm caused by the low pass filter (LPF) in the d‐q detection method, an improved series repetitive control (ISRC) structure is proposed in this paper. Using attenuation factor and correction factor to improve the series repetitive controller, the ISRC contains a negative resonance peak with a peak value of 150 dB at the 6 k harmonic frequency, and the amplitude gain is 0 dB at frequencies outside the 6 k harmonic frequency. Therefore, ISRC can achieve good attenuation effect on 6 k harmonics while maintaining the same gain at other frequencies. ISRC is used instead of LPF in the traditional d‐q detection and this strategy improves the dynamic response of the system while guaranteeing its steady state performance. Finally, simulations and experiments verify the feasibility of the strategy. [ABSTRACT FROM AUTHOR]

Summary: The non‐permanent dc short‐circuit fault is a crucial issue in overhead high voltage dc transmission (HVDC) lines. In this paper, a cross connected (CC) cell also known as hexagonal switch cell (HSC) based modular multilevel converter (MMC) with dc short‐circuit fault ride through feature is addressed for an HVDC system. During normal operation, the CC cell‐MMC is capable of producing an identical number of levels while using fewer power devices than full‐bridge (FB) and clamp double sub‐module (CDSM)‐based MMCs. Similarly to the FB‐MMC and CDSM‐MMC, the provided CC cell‐MMC not only blocks the dc fault current but can also function as a static synchronous compensator (STATCOM) during a DC‐Bus fault. The Proposed control technique uses MMC as a STATCOM to inject reactive power during a pole‐to‐pole DC‐Bus fault to keep the grid stable. The control approach comprises injecting zero‐sequence voltage into each phase to balance the mean voltage of capacitors and arm currents. The fundamental zero‐sequence voltage is obtained by a simple stationary reference frame‐based controller. The control strategy's efficacy is evaluated in MATLAB and confirmed in the Opal‐RT environment. [ABSTRACT FROM AUTHOR]

With the growing distributed PV installation rate in distribution systems, voltage regulation difficulties such as local voltage violations and fluctuations have become common. To solve the voltage regulation problems, the local voltage regulation method using volt‐var (VV) function is effective for its high regulation speed, high accuracy, and flexibility. However, there are still hurdles on real application, such as parameter setting difficulties, insufficient voltage fluctuation mitigation effect, and unfairness of reactive power generation between PV customers. To further improve the VV function, this paper proposes a PID closed‐loop based VV function and mode‐switching function of PV smart inverter (SI). To validate the proposed methods, numerical simulations were conducted using a 6‐feeder distribution system model based on the JST‐CREST 126 distribution feeder model. According to the simulation result, the proposed method can better mitigate the local voltage violation compared to basic VV function based on the VV curve, also improve the fairness between PV customers, while the total reactive power generation and tap operations increases for the aim of more adequate voltage regulation. © 2024 The Authors. IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Reactive and active power vector control of induction generators (IG) are essential requirements for generating high-quality electricity from wind power. These control objectives are challenging and difficult to achieve when using traditional strategies based on estimating reactive/active power, hysteresis comparators, and proportional-integral (PI) regulators due to load variations, changes in the value of rotor resistance, etc. So, to achieve these control objectives, this paper proposes a novel technique for the rotor side converter of IG-based contra-rotating wind power (CRWP) systems. The control based on the neural synergetic-super-twisting controller (NSSTC) is designed to minimize IG power ripples and improve the quality of current. The characteristics of the NSSTC-based strategy are presented, evaluated, and compared to the traditional direct field-oriented command (DFOC) based on traditional PI controllers and other reference techniques from the literature, highlighting that the NSSTC-based strategy is simpler to apply and more robust and performant than others classical nonlinear strategies. Comparative simulations are carried out on both the designed DFOC-NSSTC strategy and the DFOC technique to demonstrate the performance (good quality output power, low total harmonic distortion (THD) value of rotor currents, short response time and high robustness) and advantages of the suggested nonlinear technique. [ABSTRACT FROM AUTHOR]

Presently, there exists a multitude of applications reliant on superconducting magnetic energy storage (SMES), categorized into two groups. The first pertains to power quality enhancement, while the second focuses on improving power system stability. Nonetheless, the integration of these dual functionalities into a singular apparatus poses a persistent challenge. Considering this, this paper proposes a multi-functional device based on SMES, encompassing both power quality enhancement and power system stability improvement capabilities. It incorporates power quality enhancement features such as current harmonic filtering, active power smoothing, reactive power compensation, and critical load protection, while also furnishing virtual inertia to bolster grid frequency. Simulation results validate the effectiveness of the proposed methodologies. [ABSTRACT FROM AUTHOR]

Distributed photovoltaic (PV) in the distribution network accounted for an increasing proportion of the distribution network, and the power quality of the distribution network of the power quality problem is more and more significant. In this paper, the voltage regulation methods for low-voltage distribution networks containing high-penetration PV are investigated. First, the working principles of the four voltage control methods are introduced: energy storage system configuration, regulating the reactive power output of PV inverters, restricting the active power output of PV, adjusting the switching positions of on-load regulator trap changer and distribution network reconfiguration, and then, in combination with the recent related research, the optimization of each method is compared horizontally with its respective concerns and characteristics. The optimization of each method is compared horizontally with the recent studies to find out the focus and characteristics of each method, and the shortcomings of each method are explored. Coordinated voltage control through multiple flexibility resources has become the mainstream voltage regulation scheme, and distribution network voltage regulation is considered from the perspective of flexibility resources. The three types of flexibility resources, namely, source, network, and storage, have been widely used in distribution network voltage regulation. Although load-side resources have become one of the main regulation resources of the new type of power system, the current study introduces less about the participation of load-side flexibility resources in voltage regulation of LV distribution networks and advancing the application of load-side resources in voltage regulation of LV distribution networks is the focus of future research. Then, the important role of load-side flexibility resources in voltage regulation is described in three parts, namely, the important role of load-side resources, the development trend, and the suggestions for promoting the coordination of source-network-load-storage flexibility resources, aiming to promote the application of load-side resources in voltage regulation in LV distribution networks, and the suggestions and programs are proposed for the technological challenges faced by voltage regulation. In the context of today's new power system emphasizing the interaction of source, network, load, and storage, new technologies and methods for solving voltage problems in LV distribution networks are prospected, with a view to providing certain reference value for the actual operation and optimization of distribution network systems. [ABSTRACT FROM AUTHOR]

Grid-connected power inverters are indispensable in modern electrical systems, playing a pivotal role in enhancing the integration of renewable energies into power grids. Their significance, primarily when functioning as grid-forming inverters, extends to maintaining the grid's inertia and strength—a distinct advancement over traditional grid-following operations. As grid-forming inverters, these devices emulate the characteristics of synchronous generators and can act as robust voltage sources, providing essential ancillary services. This behavior is particularly relevant when integrating energy storage systems on the converters' direct current side. Among the various inverter topologies, the current source inverter (CSI) has emerged as a promising yet underexplored alternative for grid-forming applications. CSIs, when paired with their AC output filters, can effectively operate as voltage sources, utilizing control strategies that facilitate the integration of renewable energies into the electrical system. Their design inherently manages output current fluctuations, reducing the need for restrictive current limitations or additional protective measures. This paper examines the operational region of CSIs, obtained through detailed modeling, to explore their advantages, challenges, and potential for enhancing grid-connected systems. Analyzing the operating region from the converter model verifies the limits of where the converter can operate in a plane of active and reactive powers. For a small prototype model operating with 7 amperes in DC and 120 V in AC, it is possible to supply or absorb active power exceeding 1000 W and manage maximum reactive power values around 500 VAr, as determined by its operating region. Simulations also confirm that small changes in the control reference, as little as 5%, towards the region's right limits cause significant oscillations in the dynamic control responses. This research aims to deepen our understanding of CSIs' operational capabilities and highlight their unique benefits in advancing grid-connected systems and promoting the integration of renewable energy using this technology. [ABSTRACT FROM AUTHOR]

The distorted supply voltage degrades the control performance of a unified power quality conditioner (UPQC). This problem causes incorrect calculations in the harmonic identification and reference signal generation processes. This paper proposes a modified harmonic identification of the UPQC. The reference compensating current calculation for the shunt active power filter (shunt APF) is developed using the sliding window with the Fourier analysis (SWFA) method. In addition, the variable power angle control (PAC) is applied to operate the reference signal generation of the series APF and the shunt APF of the UPQC. Under the distorted voltage and nonlinear load conditions, the proposed approach can provide accurate reference compensating signals and successfully share the load reactive power compensation between the shunt APF and the series APF. In this work, a three-phase, three-wire power system with linear and nonlinear loads was implemented. The proposed method was validated using the processor-in-the-loop technique on an eZdsp™ F28335 board and the MATLAB/Simulink program. The testing results indicated that SWFA has excellent filtering performance and enhances harmonic identification compared to the operation without any filter or with low pass filters (LPF). With the proposed approach, the percentage of total harmonic distortion of voltage and current could be maintained within the IEEE519-2022 standard, and the magnitude of the RMS voltage across the load was in the recommended range specified by ANSI C84.1-2016. [ABSTRACT FROM AUTHOR]

State estimation stands as one of the most crucial applications in energy management systems of control centres, ensuring the secure operation of the power system. The real‐time availability of accurate system variables, including voltages, currents, and power flows, presents an excellent opportunity to consider the actual network characteristics, including imbalances. This paper presents a linear and non‐iterative method to solve the three‐phase state estimation problem in transmission systems with unbalanced loading. The method utilises supervisory control and data acquisition measurements obtained from remote terminal units. The formulation is based on complex variables derived from traditional supervisory control and data acquisition measurements, with assumptions made regarding the availability of certain three‐phase bus voltages, as well as a number of three‐phase currents and active and reactive power flows. The proposed algorithm employs the classical weighted least squares technique for solving the three‐phase state estimation problem. Due to its straightforward and linear nature, the method ensures no convergence issues. To validate its effectiveness, the proposed method is validated on a three‐bus network and the IEEE 39‐bus network simulated using the three‐phase model within the DIgSILENT Power Factory environment. [ABSTRACT FROM AUTHOR]

Due to the environment's instability, to reduce inconsistent power supply it is preferable to connect two or more RES in a grid. Harmonics and other power quality issues are introduced into the distribution grid as a result of integrating these Hybrid Renewable Energy Storage (HRES) with nonlinear loads, which is a significant concern for the utility and the consumers, respectively. With the use of the Unified Power Quality Conditioner (UPQC), power quality problems such as voltage interruptions, actual power, and reactive power can be reduced. For optimal operation of the series and shunt compensator of UPQC, the outputs of the converters are controlled by PWM signals, which are optimally tuned by controllers implemented with updated algorithms. An optimized Hybrid metaheuristic-assisted collateral controller comprising of fractional-order proportional integral derivative (FOPID) controller cum (proportional integral (PI) controller for the enhancement of the Three-Phase HRES system-based Distribution Grid integrated with UPQC is developed in this paper. The UPQC reduces the harmonics that non-linear loads feed into the power supply and power quality concerns. The DC link voltage regulation and controller optimization are achieved with the optimal tuning of gain parameters, fractional orders and weight parameters using a hybrid Metaheuristic Algorithm named Amplified Slime Mould with WildeBeest Herd Optimization (ASM-WHO) Algorithm. The proposed system is developed in MATLAB Simulink to compare the effectiveness of compensation for voltage sags and surges and total harmonic distortion (THD) to more traditional approaches, UPQC with PI controller, FOPID-PI controller, FOPID-PI with Chicken Swarm Optimization (CSO), SOA, SMA, and WHO optimization. The settling time for the proposed FOPID-PI controller with ASM –WHO is 147.27 s, which is 1.7%, 13.78%, 1.338% and 13.66% better than the controller without optimization, the proposed collateral controller method with either SOA or CSO or SMA, WHO optimization and PI controller respectively. [ABSTRACT FROM AUTHOR]

Summary: With the increase in the penetration level of renewables into the grid, the virtual synchronous generator (VSG) concept has emerged as an attractive solution for controlling grid‐tied inverters. The variation in reactive power also affects the real power of the system as well. To address the voltage variations and phase angle variations occurring because of the energy storage elements, the control of the reactive power loop (RPL) is important. Also, it is used to maintain voltage regulation and improve the power factor of the VSG system. This paper focuses on the damping of oscillations occurring because of load variation by proper adjustment of the rotational inertia, damping coefficient, droop coefficient, and regulatory coefficient of reactive power with a proposed adaptive control strategy. Small‐signal analysis of the active and reactive power and point of common coupling (PCC) have been derived, and the detailed dynamic performances are analyzed. The influences of parameters perturbation on PCC voltage and reactive power were investigated. Furthermore, adaptive control includes optimizing dynamic indexes such as rise time, delay time, and response settling time. Finally, the performance and improvement in the results of VSG with and without adaptive control are compared. [ABSTRACT FROM AUTHOR]

In today's context of power generation from wind, the demand for reliable and high-performing inverters is on the rise. The quasi-Z-source inverters (q-ZSI) are gaining attention in grid-tied wind power generation systems (WPGS) when compared to conventional inverters for their inherent capability of single-stage power conversion and maximum power point tracking (MPPT) performance. However, the erratic nature of wind speed creates a constant challenge for engineers seeking to optimize the performance of wind turbines (WT). Therefore, this paper suggests a new grey wolf-optimized MPPT (GWO-MPPT) controller for q-ZSI-based grid-tied WPGS, which holds great potential for maximizing the power output of WTs. The conventional MPPT controller used in q-ZSI-based WPGS cannot guarantee stable operation during large variations in wind speed. The GWO-MPPT controller can immediately respond during wind speed variations and trace the maximum power point (MPP) without fluctuations around it, thus improving the MPPT performance. The GWO algorithm estimates the optimum rectifier DC voltage for each wind speed to locate the MPP and subsequently determines the shoot-through duty ratio for the q-ZSI. In addition, this work introduces a decoupling current control strategy supported by dual frequency modulation (DFM) for managing the grid's active and reactive power flows. The functionality of the proposed controllers is rigorously examined using the MATLAB/Simulink tool through extensive simulations. Finally, their practicality is evaluated through an experimental hardware setup. This integrated approach thoroughly investigates the controllers' effectiveness and suitability for practical implementation in WPGS. [ABSTRACT FROM AUTHOR]

Voltage instability in power systems arises due to the shortage of reactive power and may cause abnormally low bus voltages leading to a partial or complete blackout. In order to maintain the system voltages within a safe limit, voltage control techniques such as shunt capacitor banks, Static VAR Compensators (SVCs), load shedding, and transformer tap-changer blocking, are employed. In this paper, a novel receding-horizon Model Predictive Control (MPC)-based voltage controller is proposed, which, by optimally controlling generator reactive power and SVC output, maintains the voltage stability of a power system. For this, a sensitivity-based analysis is performed to design a state-space model of the power system. The frequency and voltage dependency of load and generation are considered in the system equations. The voltage control is done step-wise, and the optimal control action in each step is calculated by minimizing a cost function subject to a set of relevant constraints. Different Voltage Stability Indices (VSIs) are used as a measure of voltage stability and also used in the constraints for the optimization problem. The performance of the proposed controller is evaluated on IEEE 9-, 39- and 118-bus systems, considering different types of loads and contingencies. [ABSTRACT FROM AUTHOR]

The optimal operation of energy resources in smart distribution system (SDS) is one of the significant concerns that must be properly addressed and is of utmost importance. By optimal operation the operating point of distributed energy resources (DERs) and the strategy of energy exchange with the upstream network can be appropriately determined. Therefore, this work aims to investigate energy loss-constrained optimal operation of SDS. The SDS comprises of dispatchable distributed generations (DDGs), solar generation and electric vehicles (EVs). Participation of DDGs and EVs in both active and reactive power is considered in this paper. The proposed operation of SDS aims at minimizing the total operating cost of SDS. Moreover, to improve the technical efficiency of SDS, energy loss is added as one of the constraints in the optimization problem. The operational problem of SDS with reactive power support from EVs is modeled as a mixed integer second-order cone programming problem and solved using MOSEK solver. Different case studies are framed and compared to investigate the effect of considering energy loss constraint and reactive power from EVs. Simulation results verify the efficacy of proposed model in optimally coordinating different DERs in SDS. [ABSTRACT FROM AUTHOR]

The reactive power optimization of an active distribution network can effectively deal with the problem of voltage overflows at some nodes caused by the integration of a high proportion of distributed sources into the distribution network. Aiming to address the limitations in previous studies of dynamic reactive power optimization using the cluster partitioning method, a three-stage dynamic reactive power optimization decoupling strategy for active distribution networks considering carbon emissions is proposed in this paper. First, a carbon emission index is proposed based on the carbon emission intensity, and a dynamic reactive power optimization mathematical model of an active distribution network is established with the minimum active power network loss, voltage deviation, and carbon emissions as the satisfaction objective functions. Second, in order to satisfy the requirement for the all-day motion times of discrete devices, a three-stage dynamic reactive power optimization decoupling strategy based on the partitioning around a medoids clustering algorithm is proposed. Finally, taking the improved IEEE33 and PG&E69-node distribution network systems as examples, the proposed linear decreasing mutation particle swarm optimization algorithm was used to solve the mathematical model. The results show that all the indicators of the proposed strategy and algorithm throughout the day are lower than those of other methods, which verifies the effectiveness of the proposed strategy and algorithm. [ABSTRACT FROM AUTHOR]

The increasing level of harmonics in the power grid, driven by a substantial presence of coupled inverter-based energy resources (IBRs), poses a new challenge to power grid transient stability. This paper presents the findings from experiments and analytical studies on the impact of the topological configuration of coupled IBRs on the level of power flow harmonics in a distribution grid: (i) our findings report that the impact of grid topology on harmonics is nonlinear, which is in contrast to the common perception that the power grid operates as a large linear low-pass filter for harmonics; (ii) importantly, this study highlights that the influence of the topological configuration of inverters on the reduction of system-level harmonics is more substantial than the effect of line impedance, emphasizing the significance of grid topological configuration; (iii) furthermore, the observed reduction in harmonics is attributed to a harmonic cancellation effect achieved through self-compensation by all the coupled inverters without affecting the active power flow in the power grid. These findings propose a new approach to limit the penetration of complex IBR harmonics in the power grid from a system-wide perspective. This approach significantly differs from the component-level or localized solutions used today, such as inverter control, power filtering, and transformer tap changes. [ABSTRACT FROM AUTHOR]

This paper analyzes the behavior of an electrical power system when N-1 contingencies occur in the transmission stage, which can be produced by incorrect operation of the protection relays, phenomena of natural origin, or increased loadability, which affect the operation and reliability of the electrical system. The operation output of a transmission line results in the variation of the nominal values of the electrical parameters involved because they disturb the stability of the generation, transmission systems, and the supply of electrical energy to the loads, such as voltages and angles of the nodes and the active and reactive power of the system. The proposed methodology was based on analyzing the different electrical parameters of the power system, quantifying the contingency index in a state of regular operation, and comparing it to operation in contingency N-1, with which the most severe contingency was determined and, therefore, achieved; identifying contingencies that can cause system collapses; improving the contingency index from 23.08555 to 22.9276624 for the L16–19 contingency and to 22.9795235 for the L21–22 contingency, which are the most severe contingencies determined with the proposed methodology. To test the proposed methodology, the IEEE 39 bus-bar test system was considered, and the elements that should be implemented to avoid the vulnerability of the power system to N-1 contingencies were determined. [ABSTRACT FROM AUTHOR]

The fast-growing influence of grid-interfaced photovoltaic (PV) networks makes it necessary to adhere to grid-code (GC) regulations. These regulations mandate that PV systems inject active power both during and after the grid fault occurrence, as well as provide reactive current to the grid during voltage dips, in order to prevent power system stability concerns. In this context, two novel control schemes have been proposed in this paper for grid-connected photovoltaic networks that can support low-voltage ride-through (LVRT). The proposed control techniques have been demonstrated to be simple and efficient in the event of severe voltage dips, i.e., work up to a voltage drop of 90% of the nominal grid voltage. Our first approach involves an enhanced reactive current injection strategy that provides reactive power support to the power grid during voltage dips without any additional devices. The control structure is comprised of a voltage level estimator and a reactive current controller. The voltage level estimator obtains power grid voltage, while the reactive current controller computes active−reactive current commands. It is particularly noteworthy that the proposed scheme generates active current as much as possible according to the voltage dips and tracks the active current reference correctly, where conventional strategies fail to cope. The second control method for LVRT presented in this research work involves using hardware, specifically a crowbar. The use of a crowbar is the most straightforward method to provide support to the power system, bypassing over-current during voltage dips and keeping the current within the normal converter rating. The control strategies proposed in this paper are validated in MATLAB/Simulink under symmetrical and unsymmetrical severe voltage dips as well as grid voltage harmonics, and a detailed comparison study with a state-of-the-art PQ-based fault-ride-through controller has been conducted. [ABSTRACT FROM AUTHOR]

The paper presents a proposed system that supplies a 400 Hz single-phase onboard grid from the DC onboard bus. This system enables independent compensation of reactive power in the AC grid. Independent control of active and reactive power flow requires the decomposition of current in the grid into active and reactive components. Independent control of active and reactive power requires the use of synchronizers that operate in the dq frame system. If synchronization is performed with a single-phase grid, the transformation of dq requires the virtual quadrature signals. Standard quadrature signal generation systems use a second-order generalized integrator. To improve the dynamics of the system, the paper proposes a new quadrature generator that operates on the basis of trigonometric calculations instead of a second-order integration system. The developed system was implemented in a proportional-resonant current control system. Tests carried out in steady state and in dynamic states related to typical grid disturbances proved significantly better dynamic properties than those of a standard integrator-based system. [ABSTRACT FROM AUTHOR]

This paper presents a case study in which the influence of the 6-pulse thyristor-bridge input reactor size on the shunt active power filter (SAPF)'s work performance is investigated. The purpose of using an SAPF in the power system is in most cases for fundamental harmonic reactive power compensation, harmonics and asymmetry mitigation. The work efficiency of such a filter depends not only on the designed control system, interface filter and dc-link capacitor parameters, but also on the parameters of the electrical system in which it is connected. Therefore, it is necessary to study and know the power system (supplier and consumer sides) before its installation. For instance, in the electrical system with diode or thyristor-bridge as loads, the SAPF performance efficiency may not be satisfied due to the high rate of current change (di/dt) at the points of commutation notches. In this paper, the performed simulation and laboratory experiments show that for a better operating efficiency of the SAPF, the input reactor parameters should be selected based not only on the effective reduction in the inverter switching ripple or the control system demand, but also on the parameters of the load, such as the parameters of the diode or thyristor-bridge input reactor. Apart from the experimental demonstrations on how the input reactor size influences the SAPF work efficiency, the novelties in this paper are: the formulated recommendations on how to choose the SAPF input reactor parameters (the SAPF is more efficient in terms of harmonics, asymmetry and reactive power mitigation when the inductance of its input reactor (L-filter) is smaller than the one of the diode or thyristor-bridge input reactor); the proposed SAPF control system; the proposed expressions to compute the SAPF input reactor inductance, DC voltage and capacitor. [ABSTRACT FROM AUTHOR]

Oscillations, commonly known as a universal, propagative, and intricate event in the new power system, often give rise to generator tripping and load shedding, not only adversely affecting the power flow limit and the power angle stability but also posing threats to the lines of defense for stability and protection. Traditionally, emphasis has been laid on post-fault oscillation management, an emergency measure to deal with the impact and damage that have already affected the power grid. As such, this paper focuses on an oscillation prediction technique to detect oscillation energy early and intervene proactively to prevent further faults. This technique effectively lessens the damage caused by impacts and disconnects to the power grid. Firstly, this paper proposes the concept of disturbance power density and establishes the correlation between disturbance energy and the time domain, thereby exploring a method for evaluating the pattern of electrical quantities before power system oscillation. Secondly, it speeds up the time it takes to detect faults by catching nuances of voltage-current phase angle and impedance. Lastly, it puts forward a technique to cope with the intricacy and variety of power grid equipment using the convolutional neural network (CNN). This technique incorporates an integrated attention mechanism within a one-dimensional CNN model to capture the implicit mapping between voltage, active power, and reactive power at any time in the power system. This enables the model to self-learn multi-device characteristics and enhances the possibility of using theory in practical ways. Moreover, practical case studies also show that the prediction technique proposed in this paper can effectively issue warnings eight minutes before the occurrence of oscillation. [ABSTRACT FROM AUTHOR]

The increasing penetration rate of distributed energy brings more complex problems of voltage quality, safety and stability to the distribution network. A single optimal configuration of reactive power or energy storage is difficult to meet the increasingly diversified needs of modern power grids. This paper proposes a configuration strategy combining energy storage and reactive power to meet the needs of new energy distribution networks in terms of active power regulation and reactive power compensation, and to achieve tradeoff optimization in flexibility, voltage quality and economy, so as to adapt to the influence of new energy with different permeability. Firstly, the safety and stability evaluation system of distribution network is established with the target of flexibility demand and reactive power demand. Secondly, considering the coupling of planning layer and operation layer, a two‐layer model of energy‐reactive power optimization is established. After that, the gray wolf algorithm is used to solve the model, which enhances the global space exploration ability and reduces the possibility of falling into the local optimal. Finally, the improved IEEE33 node power distribution system is used for simulation test to verify the rationality and effectiveness of this scheme. The simulation results show that the scheme proposed in this paper can effectively improve the economy, security and stability of the distribution network, and can obtain an optimal configuration scheme with multi‐objective considerations under different new energy penetration rates. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Nonlinear loads, crucial components of power system grids, pose a challenge due to harmonics injection. This work tackles this issue with a novel modified green plug–switched filter compensation scheme using fuzzy logic controllers. This innovative scheme presented in this paper utilizes dual action pulse width modulation to ensure switching functions from harmonics reduction and capacitive compensation for inrush nonlinear-type AC loads. The scheme's multi-loop regulations and online switching effectively handle dynamic-type slow-acting inrush, motorized- and other rectifier-type nonlinear loads, enhancing the power factor, power quality at source and load buses, and reducing the total harmonics distortion at the key source and sensitive nonlinear load buses. A simulation model in the MATLAB/SIMULINK-2023b software environment demonstrates the efficiency of the proposed FACTS technique. The modulated dual mode switched filter-capacitive compensation scheme controlled by a fuzzy logic controller ensures less harmonics distortion and improved voltage stabilization. The results show that voltage, current, active power, reactive power, power factor regulation, and effective energy utilization are achievable with the designed Flexible AC Transmission System-Modulated Filter Capacitor Compensation–Switched Filter Compensator (FACTS-MFCC-SFC). The switched modulated AC green plug filter significantly improves power quality and enhances power factor in cases of inrush and nonlinear loads. [ABSTRACT FROM AUTHOR]

Wind power systems (WPs) are complex non‐linear systems with varying parameters affected by environmental changes, including wind speed fluctuations. Extracting maximum power from WPs poses a significant challenge due to these factors. Direct power control (DPC) is a highly effective technique known for its simplicity and ease of implementation. However, it suffers from power ripples caused by the use of hysteresis comparators and switching tables that operate at variable frequencies. To address this issue, this paper presents the robust neural controller (NC) based on DPC, which replaces the switching tables. The Double‐Fed Induction Generator (DFIG) is the chosen generator for the studied WP system due to its advantageous features. The NC‐DPC effectively regulates the exchange of active and reactive powers between the DFIG and the system, maximizing power extraction from the WP system while reducing Total Harmonic Distortion and enhancing overall system quality. The effectiveness of the NC‐DPC is evaluated through MATLAB simulations and further supported by experimental data obtained using the Real‐Time Interface of the dSPACE‐DS1104 Controller card. [ABSTRACT FROM AUTHOR]

The conventional topological approach to eliminate the multiple-input DC voltage requirement in multilevel inverter configurations for synthesizing high-output voltage levels is to deploy split capacitor banks at the input terminal. This method stipulates a less expensive, light weight, and reduced size inverter system. However, the excessive demand for several capacitor banks and the complex voltage balancing strategy associated with this conceptual approach poses numerous limitations in their deployment. In view of these drawbacks, this study proposes a self-balanced, single-phase, nine-level switched-capacitor-based inverter topology consisting of a single-input DC voltage, an auxiliary circuit, and an H-bridge circuit unit. A commensurate single carrier-based sinusoidal pulse-width modulation scheme is developed for the proposed power circuit control, enabling the synthesis of a nine-level output voltage waveform whose amplitude is four times the input voltage value. Detailed power circuit operations and switching functions are adequately provided in the proposed topology. A comparison between the proposed inverter and its recent counterparts in terms of component count, cost involvement, and output voltage-boosting ability is duly carried out using Python data visualization. Results reveal that the proposed inverter competes well in these three criteria. For varying R–L load values, the inverter has the capability of high active and reactive power delivery. Its dynamic response for step changes in the modulation index under these power-mode operations is presented in this paper. For high active power-mode operation, efficiencies of 98.27% and 98.92% under light- and heavy-load conditions, respectively, are obtained on a 3-kW-rated inverter prototype. [ABSTRACT FROM AUTHOR]

Electric ship propulsion is considered one of the most promising alternatives to conventional combustion systems. Its goal is to reduce the carbon footprint and increase a ship's maneuverability, operational safety, and reliability. The high requirements for ship propulsion make permanent magnet synchronous motors (PMSMs) an attractive solution due to their characteristics. This paper discusses the control problem of a PMSM based on the input–output feedback linearization method combined with the optimal and adaptive control techniques. The method presented here integrates the parameter tuning process with the optimal design of the baseline controller. Since the load disturbances are treated as an additional unknown parameter, there is no need to introduce an integral action to deal with the resulting steady-state error. An important feature of the designed controller is the so-called energetic optimization of the system; i.e., in addition to the aforementioned adaptive and optimal controller, it has a feature of ensuring zero reactive power consumed by the system. The performed simulations of the machine speed stabilization process confirmed the high efficiency of the proposed controller despite the assumed uncertainty of the system parameters and environmental (load) disturbances. Besides achieving high-quality control, an essential feature of this approach is the elimination of the tuning problem. [ABSTRACT FROM AUTHOR]

With the expansion of the scale of electric power, high-quality electrical energy remains a crucial aspect of power system management and operation. The generation of reactive power is the primary cause of the decline in electrical energy quality. Therefore, optimization of reactive power in the power system becomes particularly important. The primary objective of this article is to create a multi-objective reactive power optimization (MORPO) model for distribution networks. The model aims to minimize reactive power loss, reduce the overall compensation required for reactive power devices, and minimize the total sum of node voltage deviations. To tackle the MORPO problems for distribution networks, the improved sparrow search algorithm–particle swarm optimization (ISSA-PSO) algorithm is proposed. Specifically, two improvements are proposed in this paper. The first is to introduce a chaotic mapping mechanism to enhance the diversity of the population during initialization. The second is to introduce a three-stage differential evolution mechanism to improve the global exploration capability of the algorithm. The proposed algorithm is tested on the IEEE 33-node system and the practical 22-node system. The results indicate a reduction of 32.71% in network losses for the IEEE 33-node system after optimization, and the average voltage of the circuit increases from 0.9485 p.u. to 0.9748 p.u. At the same time, optimization results in a reduction of 44.07% in network losses for the practical 22-node system, and the average voltage of the circuit increases from 0.9838 p.u. to 0.9921 p.u. Therefore, the proposed method exhibits better performance for reducing network losses and enhancing voltage levels. [ABSTRACT FROM AUTHOR]