Search

Inverter‐dependent renewable energy sources are being integrated into the grid, raising several stability‐related difficulties. This is because these renewable sources have less inertia than synchronous generators. Since the power grid's overall inertia has improved, the introduction of virtual synchronous generators (VSG) has gained much attention. A robust microgrid system requires an effortless transition from grid‐connected to autonomous mode. This can be easily achieved with the help of VSGs. The angle, frequency, and magnitude of the grid voltage needed for synchronization have traditionally been determined by phase‐locked‐loop (PLL). The virtual synchronizing torque and voltage‐based synchronization controller for simple switching between islanding and grid‐connected modes are presented in this study. The proposed method requires no additional controller to identify the unwanted islanding situations because the operating mode can be identified with the help of synchronizing torque. The proposed method does not need to shift to different control algorithms while changing between grid connection and stand‐alone modes. The effectiveness of the suggested controller is established by comparing the experimental prototype of the VSG incorporating the proposed controller to the existing synchronization methods. [ABSTRACT FROM AUTHOR]

The highly uncertain and uncontrollable power output of renewable energy sources (RES), when integrated into power systems at high penetration levels, reduces system inertia and introduces uncertain changes in system structure, parameters, and frequency response characteristics. This renders traditional frequency regulation analysis methods and frequency response models inapplicable, lacking a generalized model to describe renewable energy's participation in frequency regulation. Thus, this paper proposes a method where RES utilize suitable means to reduce load, thereby contributing to frequency regulation. Furthermore, employing Virtual Synchronous Machine (VSM) technology, these renewable energy units emulate the inertia and droop characteristics of Synchronous Generators (SG), enabling their equivalent modeling alongside traditional generators within a single-machine aggregate model. An SFR (System Frequency Response) model integrating renewable energy's frequency regulation has been established. This model enables the analysis of the relationships between the system's equivalent droop coefficient and the frequency nadir, nadir time, and quasi-steady-state point. Furthermore, the required equivalent droop coefficients are proposed for various sending-end system capacities and operating conditions. Finally, the model's validity and accuracy are confirmed through a modified WSCC 4-machine 10-bus system, offering theoretical underpinnings for stable system operation and optimized operational planning. [ABSTRACT FROM AUTHOR]

As renewable energy sources become more integrated into the power grid, traditional virtual synchronous generator (VSG) control strategies have become inadequate for the current low-damping, low-inertia power systems. Therefore, this paper proposes a VSG inertia and damping adaptive control method based on multi-agent deep deterministic policy gradient (MADDPG). The paper first introduces the working principles of virtual synchronous generators and establishes a corresponding VSG model. Based on this model, the influence of variations in virtual inertia (J) and damping (D) coefficients on fluctuations in active power output is examined, defining the action space for J and D. The proposed method is mainly divided into two phases: "centralized training and decentralized execution". In the centralized training phase, each agent's critic network shares global observation and action information to guide the actor network in policy optimization. In the decentralized execution phase, agents observe frequency deviations and the rate at which angular frequency changes, using reinforcement learning algorithms to adjust the virtual inertia J and damping coefficient D in real time. Finally, the effectiveness of the proposed MADDPG control strategy is validated through comparison with adaptive control and DDPG control methods. [ABSTRACT FROM AUTHOR]

As renewable energy integration scales up, power systems increasingly depend on sources interfaced through power electronic converters, which lack rotating mass and substantially diminish system inertia. This reduction in inertia, coupled with the complex and diverse control strategies governing power electronics, presents significant challenges in accurately assessing the equivalent inertia levels within modern power systems. This paper introduces an online method for estimating the inertia time constant of power nodes, grounded in the node power flow equation, to address these challenges. The approach begins by deriving the rotor motion equation for synchronous generators and defining the inertia time constant of power nodes through an analysis of the power flow equations. Real-time frequency and voltage phasor data are collected from system nodes using phasor measurement units. The frequency state of the power equipment is then characterized using a divider formula, and the equivalent reactance between the power equipment and the node is further derived through the node power flow equation. This enables the real-time estimation of the equivalent inertia time constant for power nodes within the system. The effectiveness of the proposed method is demonstrated through simulations on the WSCC9 system, confirming its applicability for real-time system analysis. [ABSTRACT FROM AUTHOR]

Building a high-proportion renewable energy power system is a key measure to address the challenges of the energy revolution and climate change. However, current high-proportion renewable energy systems face issues of frequency instability and voltage fluctuations. To address these challenges, this paper proposes a novel topology for a stator free speed regulating wind turbine generation system. The stator free speed regulating machine connects a gearbox and a synchronous generator, forming a flexible drive chain that increases system inertia and enhances frequency stability in high-proportion renewable energy power systems. The synchronous generator at the end of the drive chain can be directly connected to the grid without the converter, thanks to the speed regulation provided by the stator free speed regulating machine, thus avoiding harmonic pollution caused by power electronic devices in traditional wind turbines, enhancing the reactive power support capability, and improving voltage stability in high-proportion renewable energy systems. Given that the proposed stator free speed regulating machine consists solely of a rotating inner and outer rotor without a stator, traditional motor control strategies are not applicable. Therefore, this paper focuses on developing control strategies for the stator free speed regulating machine, employing a dual closed-loop PI control strategy with an outer loop for speed and an inner loop for current, based on flux orientation of the outer rotor. Simulation experiments will validate the feasibility of the proposed stator free speed regulating wind turbine generation system topology and the effectiveness of the control strategy. [ABSTRACT FROM AUTHOR]

The mechanism of oscillations that occur in the system connected to renewable energy sources is complex, generally including negative damping oscillation, limit induced oscillation etc. Combining with the dynamic characteristics of the low‐dimensional system after limit working, this paper analyses the mechanism of a type of limit induced oscillation that occurs when the output of the DC voltage outer loop continuously touches the limit for single‐machine infinite‐bus system of permanent magnet synchronous generator with positive damping under a large disturbance. Specific study as follows: firstly, a non‐smooth state space model of single‐machine infinite‐bus system of permanent magnet synchronous generator with nonlinear state limit (clarified as a Filippov system) is established. Secondly, the small disturbance characteristics of the system are analysed when the limit does not work. Thirdly, the piecewise dynamic description of the system is analysed with the limit working, and the reason that the final contraction of the system to an eight‐dimensional manifold is explained based on mathematical derivation and physical characteristics. Finally, the characteristics of equilibrium point of the system in a low‐dimensional manifold are analysed when the limit continuously working, revealing that the existence of a pair of conjugate unstable eigenvalues in the low‐dimensional system is the reason of system oscillation. [ABSTRACT FROM AUTHOR]

As the application of renewable energy sources continues to increase, the virtual synchronous generator (VSG) has been proposed and received widespread attention. In China, new energy stations are typically situated at the transmission end of LCC‐HVDC lines. A failure in DC commutation can lead to overvoltage at the DC transmission end, thus posing a significant risk of disconnection from the grid due to the occurrence of overvoltage. Compared to when low‐voltage occur, it was discovered that, during overvoltage, VSGs face difficulties in rapidly attaining the preset power and transient instability. These issues can significantly impact the voltage support capability of the VSG. To address these concerns, an enhanced control strategy has been proposed. The control strategy sets reasonable power reference values, leveraging the advantage of fast voltage response in VSG by matching its voltage with virtual impedance. This ensures that the power rapidly reaches the designated reference value while reducing fluctuations in power angle. The transient power‐angle stability is validated using the energy function method. This approach enhances the reactive power absorbed by VSG, thereby mitigating transient overvoltage. Finally, simulation results from PSCAD/EMTDC validate the rationale and effectiveness of the control strategy. [ABSTRACT FROM AUTHOR]

An increase in renewable energy generation in the microgrid can cause voltage oscillation problems. To address this issue, an equivalent circuit of the microgrid was established, including a synchronous generator, grid-connected inverter, and constant power load. Then, the impact of different renewable energy generation ratios, different direct current (DC) voltage loops, and phase-locked loop control bandwidths of the grid-connected inverter on microgrid stability were analyzed. The results indicate that an increase in the renewable energy generation ratio leads to a decrease in the stability margin of the microgrid. A microgrid stability improvement method involving the parallel connection of a virtual resistor with the grid-connected inverter was proposed. The resistance value of the virtual resistor was obtained through an adaptive algorithm. This method ensures the stable operation of the microgrid under different renewable energy generation ratios. [ABSTRACT FROM AUTHOR]

With the large-scale integration of renewable energy into the grid, traditional short-circuit current (SCC) calculation methods for synchronous generators are no longer applicable to inverter-based non-synchronous machine sources (N-SMSs). Current SCC calculation methods for N-SMSs often use a single-machine multiplication method, which tends to overlook the internal variability of N-SMSs within power plants, leading to low calculation accuracy. To address this issue, this paper first derives an analytical expression for SCC in grid-connected inverters under low voltage ride through (LVRT) control strategies. Then, a single-machine steady-state SCC calculation model is proposed. Based on the classification of N-SMSs, a practical SCC calculation model for renewable power plants is introduced, balancing accuracy and computational speed. The feasibility of the model is validated through simulations. The proposed method enables simple calculations to obtain the steady-state voltage and SCC at the machine terminal, offering strong engineering practicality. [ABSTRACT FROM AUTHOR]

With the popularity of renewable energy sources, fault‐tolerant frequency stability of distributed generation systems has become a major challenge. This paper proposes an optimal frequency fault‐tolerant control method in the distributed generation system, utilizing adaptive dynamic programming combined with fuzzy critic estimation. First, based on the operational state of the system, a non‐linear dynamic model for the virtual synchronous generator is established. Then, considering the occurrence of actuator faults, the fault‐tolerant control problem is formulated as an optimal control problem, where a fault observer is designed to estimate the fault signals. Furthermore, the proposed adaptive dynamic programming method based on fuzzy critic estimation is employed to effectively solve the highly coupled nonlinear Hamilton–Jacobi–Bellman equation and ensure the state convergence of the system with uniform ultimate boundedness. The optimal fault‐tolerant control law ensures a bounded frequency error for the virtual synchronous generator system in the event of faults. Finally, the effectiveness of the optimal control method is verified by two sets of simulations. [ABSTRACT FROM AUTHOR]

The high penetration of renewable energy sources (RES) results in a low‐inertia, weak power grid. To mitigate this and restore system inertia, it has been widely proposed to operate the inverters of RES units to mimic synchronous generators; this technology is known as a virtual synchronous generator (VSG). In weak grids there is, however, strong coupling between active power (P$P$) and reactive power (Q$Q$), and any VSG technique therefore requires PQ$PQ$ decoupling in order to operate effectively. This article proposes a new PQ$PQ$ decoupling technique based on the transformation of the PQ$PQ$ power circle of a VSG connected to a weak grid: first, the power circle is translated from its designed position to that of a conventional synchronous generator (SG) connected to a strong grid, achieving partialPQ$PQ$ decoupling. Then, to achieve full PQ$PQ$ decoupling, the authors propose further to modulate the radius of the translated PQ$PQ$ power circle; this is achieved using a series resistance‐capacitance–inductance (RCL$RCL$) circuit which is virtually implemented in the VSG controller. The efficacy of the proposed scheme is validated using a modified synchronverter connected to the weak grid in representative loading scenarios. It is demonstrated that the technique achieves a decoupled PQ$PQ$ control for the synchronverter connected in a weak grid. Moreover, the modified synchronverter is capable of supporting frequency and voltage regulation in the grid without inducing large transient grid currents during mild frequency and voltage variations. [ABSTRACT FROM AUTHOR]

The energy dependency of the grid will cause its own problems because the energy generated comes from fossil fuels. On the other hand, centralized electrification using renewable energy has a high risk on frequency and voltage stability. Renewable energy depends entirely on climate conditions and has no inertia to maintain stability. Hybrid energy between grids and Inverter Based Resources (IBRs) are alternative solutions used. The research applies an inverter control scheme to IBRs to be penetrated the grid. The research will apply a zero-export load with electricity requirements to be charged to renewable power plants using grid distribution networks. The inertia less properties of renewable energy will cause interference when combined with the power grid (synchronous generator). It will also be analyzed on this study by applying the following inverter scheme by paying attention to the phase angle and synchronization against the voltage, current and frequency variables of the grid. The results obtained in this study; renewable energy can contribute 90% to the load. This is due to the Losses factor and efficiency system in the plant. Renewable energy generators feed active power to the grid as well as support grids with a Total Harmonic Distortion (THD) indicator of <10%. In the design of this hybrid power system, it is done on MATLAB software with installation configuration in accordance with IEEE standards so that it can be a reference for the installation of real-condition renewable energies with grid. [ABSTRACT FROM AUTHOR]

Modular Multilevel Converter Virtual Synchronous Generator (MMC-VSG) technology is gaining widespread attention for its ability to enhance the inertia and frequency stability of the power grid integrated with converter-interfaced renewable energy sources. However, the excitation voltage regulation in the MMC-VSG can generate equivalent negative damping torque and cause low-frequency oscillation problems similar to those in synchronous machines. This article aims to improve the system's damping torque and minimize low-frequency oscillations by introducing a Virtual Power System Stabilizer (VPSS) into the power control loop. Building on the study of dynamic interactions between various control links of the MMC, this research establishes a reduced-order model (ROM) and a Phillips–Heffron state equation for the MMC-VSG single machine infinite bus system, using a hybrid modeling approach and a zero-pole truncation method. It also analyzes the mechanism of low-frequency oscillations in the MMC-VSG system through the damping torque method. The analysis reveals that the negative damping torque produced during the excitation voltage regulation process causes changes in the virtual power angle, which in turn increases the risk of low-frequency oscillation in the MMC-VSG. To address this issue, the article proposes an optimized control method for the MMC-VSG dual power loop architecture (power-angle/excitation) VPSS. This strategy compensates for the inadequate damping torque of a single loop VPSS and effectively suppresses low-frequency oscillations in the system. [ABSTRACT FROM AUTHOR]

The ongoing replacement of synchronous machine generators (SMs) with converter-interface generators (CIGs) is raising the voltage unbalance of power systems, affecting power quality and grid stability. This paper focuses on a key power quality index for power systems, i.e., the voltage unbalance factor. The purpose of this work is twofold. First, it presents the generalization of a three-phase power flow algorithm developed by University of Padova, named PFPD_3P, to assess the voltage unbalance factors of power systems supplied by CIGs. In particular, it is demonstrated that CIGs can be modelled as three-phase PV/PQ constraints embedding their positive-, negative- and zero-sequence admittances. Then, the concept of three-phase contingency analysis is introduced. Indeed, for static security evaluation, the classical single-phase contingency analysis may no longer be sufficient, as it lacks power quality computations, e.g., voltage/current unbalance factors. Numerical simulations evaluating the unbalance factors due to different generation mix scenarios and contingencies are tested on the Italian extra-high-voltage/high-voltage (EHV/HV) grid. The choice of this network relies on its representativeness, as CIGs are the majority of new installations in the Italian generation mix. [ABSTRACT FROM AUTHOR]

The increase in renewable energy sources (RESs) in power systems is causing significant changes in their dynamic behavior. To ensure the safe operation of these systems, it is necessary to develop new methods for preserving transient stability that follow the new system dynamics. Fast-response devices such as flexible AC transmission systems (FACTSs) can improve the dynamic response of power systems. One of the most frequently used FACTS devices is the Static Var Compensator (SVC), which can improve a system's transient stability with a proper control strategy. This paper presents a reactive power control strategy for an SVC using synchronized voltage phasor measurements and particle swarm optimization (PSO) to improve the transient stability of a multimachine power system. The PSO algorithm is based on the sensitivity analysis of bus voltage amplitudes and angles to the reactive power of the SVC. It determines the SVC reactive power required for damping active power oscillations of synchronous generators in fault conditions. The sensitivity coefficients can be determined in advance for the characteristic switching conditions of the influential part of the transmission network, and with the application of the PSO algorithm, enable quick and efficient finding of a satisfactory solution. This relatively simple and fast algorithm can be applied in real time. The proposed control strategy is tested on the IEEE 14-bus system using DIgSILENT PowerFactory. The simulation results show that an SVC with the proposed control strategy effectively minimizes the rotor angle oscillations of generators after large disturbances. [ABSTRACT FROM AUTHOR]

Virtual Inertia (VI) emulation becomes crucial to improve the stability of Hybrid Renewable Energy Systems (HRES). VI emulation needs a proper VI Controller (VIC) to adapt in various working conditions. This paper proposes the stability improvement of HRES with VIC based on optimized Fractional Order Proportional-Integral-Derivative (FOPID) with Harris Hawk Optimization (HHO). The proposed method is implemented on HRES that consists of Photovoltaic Energy Systems (PVES), Wind Energy Systems (WES), Synchronous Generator Energy Systems (SGES), and Energy Storage Unit (ESU). Based on the statistical assessment and convergence curve analysis, HHO performance in finding the optimal parameters is 31.98% to 41.62% better than the other well-known algorithms. Besides that, the VIC-FOPID-HHO gives the best stability improvement compared to basic PID and the other algorithms. In uncertain behavior of RES scenarios, the improvement by VIC-FOPID-HHO is indicated by frequency nadir reduction up 89.44%, overshoot reduction up to 98.45%, and better settling time up to 61.48%. In multi-level load shedding scenarios, the improvement by VIC-FOPID-HHO is indicated by frequency nadir reduction up 93.67%, overshoot reduction of up to 97.4%, and better settling time of up to 49.94%. [ABSTRACT FROM AUTHOR]

Introduction. Weather changes lead to create oscillations in values of power extracted from renewable energy resources (RERs). These power oscillations pose significant challenges in RERs integration process with the power grid systems, through its effects on power system stability. Many studies have been performed in various methods to mitigate the output power fluctuation of wind power generation system (WPGS). Purpose. This study focuses on increasing the mitigation rate of the output power fluctuation of WPGS caused by the rapid wind speed changes during wind gusts. Superconducting magnetic energy storage (SMES) system through its properties represents an effective solution for the WPGS power fluctuation issue. WPGS and SMES systems are linked to power grid system through the point of common coupling (PCC). Methods. This paper proposes two robust controllers for controlling the SMES system. The first controller is a Fuzzy Logic Controller (FLC), which has been utilized for controlling the power exchange between the SMES coil and the PCC of the utility grid. While the second controller is a PI controller, which have been utilized to regulate the voltages between the two sides of the PCC and the DC link capacitor in the SMES system. The proposed controllers have been constructed so that can make the SMES system absorb/deliver the real power instantaneously from/toward PCC according the wind speed changes. MATLAB/Simulink has been utilized to simulate the system under study and test the performance of proposed controllers. In addition, two different wind speed scenarios have been used in the simulation. Practical value. Results of simulation have proven the effectiveness of proposed controllers so that the active power fluctuation delivered to utility grid can be reduced by up to 89 %. References 31, tables 4, figures 9. [ABSTRACT FROM AUTHOR]

Grid dynamics and control mechanisms have improved as smart grids have used more inverter-based renewable energy resources (IBRs). Modern converter technologies try to improve converters' capacities to compensate for grid assistance, but their inertia still makes them heavily dependent on synchronous generators (SGs). Grid-following (GFL) converters ensure grid reliability. As RES penetration increases, the GFL converter efficiency falls, limiting integration and causing stability difficulties in low-inertia systems. A full review of grid converter technologies, grid codes, and controller mechanisms is needed to determine the current and future needs. A more advanced converter is needed for integration with more renewable energy sources (RESs) and to support weak grids without SGs and with low inertia. Grid-forming (GFM) inverters could change the electrical business by addressing these difficulties. GFM technology is used in hybrid, solar photovoltaic (PV), battery energy storage systems (BESSs), and wind energy systems to improve these energy systems and grid stability. GFM inverters based on BESSs are becoming important internationally. Research on GFM controllers is new, but the early results suggest they could boost the power grid's efficiency. GFM inverters, sophisticated smart inverters, help maintain a reliable grid, energy storage, and renewable power generation. Although papers in the literature have compared GFM and GFL, none of them have examined them in terms of their performance in a low-SCR system. This paper shows how GFM outperforms GFL in low-inertia and weak grid systems in the form of a review. In addition, a suitable comparison of the results considering the performance of GFM and GFL in a system with varying SCRs has been depicted in the form of simulation using PSCAD/EMTDC for the first time. [ABSTRACT FROM AUTHOR]

Wind energy production systems (WEPS) are increasingly vital in the transition to renewable energy sources, with permanent magnetic synchronous generators (PMSG) being widely adopted due to their high efficiency and reliability. Developing robust control methods is essential to ensure that WEPS operate efficiently even under adverse conditions. This study focuses on optimizing control strategies for WEPS utilizing a 5‐phase PMSG and addresses challenges posed by double‐phase open fault (DPOF) scenarios. Unlike conventional second‐order sliding mode control (SOSMC) based on the super‐twisting algorithm (STA), the proposed method enhances performance by elevating the sliding surface time derivative degree to a third order and modifying the discontinuous term of STA with an arctangent function, promising to reduce chattering effects. Additionally, an adaptation law adjusts the improved STA gains, forming adaptive‐gain third‐order sliding mode control (AG‐TOSMC), which outperforms SOSMC under various disturbances such as wind speed fluctuations, parameter changes, and DPOF scenarios. The AG‐TOSMC enhances the quality of active and reactive power by reducing fluctuation ratios compared with the SOSMC. The efficiency of WEPS increases to 98.5% with AG‐TOSMC, surpassing the 93.5% achieved with SOSMC. Additionally, a DPOF test confirms the aptitude of the 5‐phase PMSG to work under degraded circumstances, supplying appropriate electrical power to the network without significant adverse effects. Numerical simulations validate the efficiency of the suggested WEPS and its control, demonstrating superior performance achieved with AG‐TOSMC. [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]

This paper presents a comparative study between four techniques recently used to improve the wind energy conversion system (WECS) to water pumping systems. The WECS is a renewable energy source which has developed rapidly in recent years. The use of the WECS in the water pumping field is a free solution (economically) compared to the use of the electricity grid supply. The control of WECS, equipped with a permanent magnet synchronous generator, has the objective of carefully maximising power generation. A comparative study between the proposed Fuzzy Logic Control, optimised using a genetic algorithm and particle swarm optimisation algorithm, and the conventional Perturb and Observe MPPT method using Matlab/Simulink, is presented. The performance of the proposed system has been verified against the generated output voltage, current and power waveforms, intermediate circuit voltage waveform, and generator speed. The presented results demonstrate the effectiveness of the control strategy applied in this work. [ABSTRACT FROM AUTHOR]

The escalating demand for energy and the mounting environmental impacts of fossil fuel usage necessitate a paradigm shift toward the integration of renewable energy sources (RES) as the core of the electrical energy sector. Solar photovoltaic (SPV) and wind-based generation have emerged as the most promising and viable solutions, leading to a significant increase in the RES-based microgrid penetration into the power grid. However, the grid-connected microgrid operation presents challenges to the stability of the main grid. Due to small aggregated physical inertia of these microgrid, there is a significant deviation in system inertia that contributes to low frequency oscillations (LFO). These oscillations have a significant risk to power system stability. In the proposed work, a grid-connected microgrid that incorporates a synchronous generator along with SPV and wind integration is investigated. A synchronized governor combined with a power system stabilizer features a cascade structure, encompassing tilt integral derivative and fractional-order proportional integral derivative with a filter to effectively mitigate the oscillations. Furthermore, this cascaded controller is optimized using the improved reptile search algorithm. The controller efficacy is validated in the MATLAB platform by subjecting it to random variations in reference torque. Comparative analysis against conventional controllers, including Proportional Integral, Lead-Lag and Fractional Lead-Lag, demonstrates superior damping efficiency of the proposed controller since it damps LFO within the time period of 15 s. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Synchronous generators have a significant role in the power system for active and reactive power control. However, the increasing usage of inverter-based power distribution systems, along with the growing prominence of renewable energy sources, raises concerns about their reliability and stability. The objective of this study is to address the reactive power load demands by employing a Static Synchronous Compensator (STATCOM) in a grid with a fuel cell stack. To reduce the threat posed by the use of inverter-sourced power transmission elements on power systems, a combined fuel cell and STATCOM structure is proposed and it is shown in the MATLAB/Simulink environment that this structure has the dynamic characteristics of a synchronous generator. This study emphasizes that the fuel cell+STATCOM structure can be used as a synchronous generator and presents a different approach in the literature. The system comprises the fuel cell, harmonic filter, STATCOM, load, coupling inductances, measurement units, and PI controller. This system is aimed to create a system that can operate stably in different reactive power requirements and meet the determined reactive power requirement in any case. This study aims to meet the need for large power synchronous generators. • Equivalent synchronous generator for modern power systems is proposed. • The active power required by the load is supplied by the fuel cell. • The reactive power required by the load is met by the STATCOM. • The system was tested for different load cases. • The operation of the proposed system was verified by simulation results. [ABSTRACT FROM AUTHOR]

Grid‐forming inverters are used for voltage regulation and frequency control in autonomous hybrid microgrids and multi‐microgrid systems by imitating synchronous generators. However, in microgrids with weak grids including low inertia levels and small X/R ratios, these inverters interact with each other, and as a result low‐frequency oscillations (LFO) arise. LFO impacts the frequency stability of multi‐microgrid systems. Nevertheless, LFO can be mitigated by the load‐frequency control system, which serves as a secondary control mechanism. However, the presence of wind turbines and photovoltaic systems in hybrid microgrids adds complexity to the operation of the load‐frequency control due to the uncertainty associated with these renewable energy resources, and various controllers have been employed. This paper proposes a novel approach to enhance the performance of the load‐frequency control system and suppress LFO. The presented technique reduces the complexity of the hybrid microgrid structure by reducing the number of controllers. The model predictive control (MPC) technique is utilized for load‐frequency control and the weight parameters of the MPC are determined using the rain optimization algorithm. The proposed method demonstrates improved dynamic response, reduced overshoot and undershoot responses, decreased controller complexity, and effective LFO suppression. The simulation results verify the effectiveness of the method. [ABSTRACT FROM AUTHOR]

System strength is both supplied and demanded in a power system during normal operations and in the presence of disturbances. This is characterised by stable voltage and frequency, supporting renewable generation such as wind and solar. Because the retirement of synchronous generators reduces system strength supply, and the connection of new inverter-based resource (IBR) generators increases demand, there is an urgent need for new sources of system strength. This paper provides an overview of the challenges brought about by grid modernisation. It highlights tangible solutions provided by synchronous condensers (SCs) to bolster grid strength, stability, and reliability while accommodating the rising influx of renewable energy sources (RESs). Furthermore, this paper examines the role of SCs in improving weak grids, voltage control, power quality, short-circuit levels, and inertia management. It introduces the role of innovative hybrid synchronous condenser (HSC) systems to boost grid reliability and resilience. It also elaborates on the optimisation strategies for SC sizing, placement, and control and outlines economic aspects of their deployment. The review also highlights future directions and challenges in SC technology, emphasising the need for ongoing research and development to enhance system design and operation. [ABSTRACT FROM AUTHOR]

Recently, the transition from conventional to renewable energy sources (RESs), from internal combustion engine vehicles to electric vehicles (EVs), and from the main grid to microgrids (MGs) are essential goals to both reduce greenhouse gas emissions and ensure the stability of power systems. However, the transitions cause new concerns in the grid including technical challenges and financial viability. This study examines the RES-based MG under realistic conditions considering the uncertainty in fleet size of EVs, emergency generator capacity, solar irradiation, and wind speed in island mode. The work aims to provide effective solutions including conventional methods alongside today's trend namely doubly fed electrical generators (DFIG), vehicle-to-grid mechanism (V2G), maximum power point tracking controller (MPPT), voltage source inverter (VSI) with high switching frequency for technical challenges, and virtual synchronous generator (VSG) mechanism for financial viability. The paper provides a guide for resizing the emergency generators capacity depending on system instability. The observations verify that the control mechanisms reinforce the system to remain stable by decreasing the range of frequency fluctuation from 3.1 to <0.05 Hz, the peak point of frequency from 51.8 to 50.05 Hz, and the emergency generator capacity from 0.7605 to 0.3420 MVAr at MATLAB and Simulink. [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]

With the gradual increase in wind power installation capacity, the proportion of traditional synchronous generators driven by fossil fuel is gradually declining. Due to the fact that wind turbines are connected to the grid through power electronic converters, which decouple rotor speeds from the system frequency and reduce system inertia levels, inadequate inertia levels can pose a threat to frequency stability when disturbances occur. To address this issue, this paper proposes a frequency regulation optimization strategy for the direct current (DC) transmission of a wind storage system. This strategy incorporates virtual inertia control and virtual droop control to adjust wind power output based on frequency deviation and rate of change. Fuzzy logic control is employed for energy storage, adaptively adjusting active power based on frequency deviation and the rate of change. Additionally, under the context of multi-DC transmission in renewable energy systems, an optimization strategy for proportion and integration (PI) parameters of the frequency limit controller (FLC) is proposed. Considering frequency deviation and DC regulation power simultaneously, the double deep Q-network (DDQN) algorithm is adopted in the simulation model to attain the optimal parameters of FLC. Simulation results conducted using MATLAB/Simulink 2022a indicate that this strategy increases the lowest frequency by 0.28 Hz and decreases the response time by 1.04 s compared with the non-optimized strategy. [ABSTRACT FROM AUTHOR]

In recent years, there has been a significant uptick in the integration of Inverter-Based Resources (IBRs) into the power grid, driven by the global shift toward renewable energy sources. The Western Electricity Coordinating Council (WECC) has developed standardized models for these inverters to facilitate their representation in system studies, playing a crucial role in evaluating IBRs, especially those modeled as grid-following inverters (GFLs). However, with the increasing prevalence of IBRs, the adjustment of grid interaction between grid-forming inverters (GFMs) and GFLs should be considered in terms of frequency stability assessment. This study investigates the optimization of synchronous generators and IBR operations in more detail. The IBR operation is evaluated with considerations for ratio and penetration. The findings suggest that with over 50% IBR penetration, GFL capacity should be reduced, and GFM capacity should be over 35% of IBR to maintain grid frequency stability. Moreover, this study also explains advanced prediction of frequency nadir, particularly the optimal ratio of WECC generic and GFM through the least squares method. Furthermore, the small-signal dynamic characteristics of WECC are studied at various gain values to investigate frequency droop control. [ABSTRACT FROM AUTHOR]

In high-penetration renewable-energy grid systems, conventional virtual synchronous generator (VSG) control faces a number of challenges, especially the difficulty of maintaining synchronization during grid voltage drops. This difficulty may lead to current overloads and equipment disconnections, and it has an impact on the security and reliability of the system, as well as limiting the dynamic reactive power support capability of the system. To solve this problem, in this study, a wind–solar hybrid power generation system is designed with a battery energy storage device connected on the DC side, and proposes a low voltage ride-through (LVRT) control strategy for the grid-connected inverter based on an improved VSG. The control strategy employs an integrated current limiting technique combining virtual impedance and vector current limiting to ensure that the VSG exhibits good dynamic power support characteristics during symmetrical faults by adjusting the setpoint value of reactive power. At the same time, it maintains the synchronization and power angle stability of the VSG itself to achieve the goal of LVRT. Simulation results show that the proposed control strategy can effectively suppress the renewable power fluctuations (about 30% reduction in fluctuations compared to the conventional strategy) and ensure the safe and reliable operation of the renewable energy sources and VSGs during grid-side faults. In addition, it provides a given reactive power support and stable grid voltage control (voltage dips reduced by about 20%), which significantly enhances the LVRT capability of the hybrid wind–solar-storage generation system. [ABSTRACT FROM AUTHOR]

Copyright of Electric Drive is the property of Electric Drive Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Grid-forming inverters (GFMs) have emerged as crucial components in modern power systems, facilitating the integration of renewable energy sources and enhancing grid stability. The significance of GFMs lies in their ability to autonomously establish grid voltage and frequency, enabling grids to form and improve system flexibility. Discussing control methods for grid-forming inverters is paramount due to their crucial role in shaping grid dynamics and ensuring reliable power delivery. This paper explores the fundamental and advanced control methods employed by GFMs, explaining their operational principles and performance characteristics. Basic control methods typically involve droop control, voltage and frequency regulation, and power-balancing techniques to maintain grid stability under varying operating conditions. Advanced control strategies encompass predictive control, model predictive control (MPC), and adaptive control, which influence advanced algorithms and real-time data for enhanced system responsiveness and efficiency. A detailed analysis and performance comparison of different control methods for GFM is presented, highlighting their strengths, limitations, and suitability for diverse grid environments. Through comprehensive studies, this research interprets the ability of various control strategies to mitigate grid disturbances, optimize power flow, and enhance overall system stability. [ABSTRACT FROM AUTHOR]

Since the creation of the first parallel electrical power systems around the world, the rotor angle stability of synchronously operating generators has been one of the most crucial and challenging problems. In modern electricity networks, including in Kazakhstan, where renewable energy technologies are rapidly emerging, the issue of stability takes on even greater importance due to the technical shortcomings of inverter-based generation. In this framework, an analysis of rotor angle transient stability was carried out when replacing existing synchronous generators with doubly fed induction generators under a certain pre-emergency mode. A critical proportion of active power generation by DFIG units was identified at which transient stability can still be maintained due to the sufficient stored kinetic energy of the synchronous machines remaining in operation. In addition, two simple solutions were investigated to improve transient stability, such as an increased time of the automatic reclosure operation and the use of special load-shedding automation. Finally, this paper proposes a novel type of flexible smart-grid automation that is capable of monitoring the main operating parameters and issuing control actions depending on inertia, the availability of wind resources, and the load of the system as a whole. For this analysis, a real power system from the Mangystau region in Kazakhstan was considered, and the PowerWorld software 23 was used. [ABSTRACT FROM AUTHOR]

With the increasing application of renewable energy sources (RESs), more and more grid‐connected voltage‐source converters (VSCs) in the grid need to operate in a "grid‐forming" manner. However, when large disturbances occur in the grid, grid‐connected converters may lose synchronization and cause the current to exceed set limits. To ensure the stable and safe operation of VSC during large disturbances and to improve the power supply capacity during voltage dips of RES, this paper proposes an emergency control method that takes into account the virtual synchronous generator (VSG) current limit and transient stability based on a large‐signal mathematical model of the VSG during fault and normal states. The method divides the operation area of the VSG into non‐emergency area and emergency area. If the operating point is in the non‐emergency region after a fault, only the active power reference value is changed to avoid current exceeding the limit and transient instability; if the operating point is in the emergency region, the current exceeding the limit and transient instability are avoided by changing the active power reference value and adding in the virtual impedance. Finally, the effectiveness of the proposed control strategy is verified by simulation. [ABSTRACT FROM AUTHOR]

To systematically analyze the impact of the DC frequency limit controller (FLC) configuration scheme on the frequency characteristics of asynchronous interconnected power grids with renewable energy integration, a comprehensive frequency analysis model for three-area asynchronous interconnected power grids including the FLC is proposed. The model is based on the SFR model considering renewable energy integration and includes a simplified model of the DC FLC. A rigorous validation of the rationality and stability of the model is achieved through detailed mathematical calculations and pole-zero analysis. Taking the local power grids as an example, the established model is used to study the difference between single- and double-sided configuration of the DC FLC, the relationship between the increase in the renewable energy penetration rate and the frequency characteristics of each regional power grid, and the influence of DC FLC configuration on the maximum acceptance ratio of renewable energy. Through data comparison and theoretical analysis, the influence of FLC configuration on the frequency characteristics of each region of the asynchronous power grid under renewable energy integration is obtained. The results show that the configuration of a bilateral FLC on the DC line has more advantages in alleviating the complementary power disturbance at both ends and obvious limitations on the non-complementary power disturbance at both ends. Compared with the configuration of the bilateral FLC, the configuration of a unilateral FLC on the weak grid has a larger proportion of renewable energy acceptance. When the DC FLC power transmission capacity is sufficient, the weak grid and the adjacent two asynchronous grid DC tie lines are configured with a single-sided FLC, and the weak grid is theoretically connected to the renewable energy penetration rate of up to 100%. [ABSTRACT FROM AUTHOR]

The integration of the renewable energy sources (RESs) into the power grid, drives a significant transformation in the conventional power generation landscape. This transition from traditional synchronous generators to inverter based RESs introduces unique challenges in maintaining the grid frequency stability due to the reduced system inertia. The inherent stochastic nature of the RES power generation, load demand, and grid inertia includes further complexity in the assessment of frequency stability. Existing studies have limitations, including neglecting the stochastic nature of RES generation and load demand fluctuations, relying on limited metrics, and lacking a comprehensive day‐to‐day assessment. To address these shortcomings of the existing approaches, this paper introduces a novel methodology for assessing frequency stability in power grids with high RES penetration. It proposes three indices for evaluating grid frequency sensitivity, resiliency, and permissibility amidst varying RES integration. Utilizing a stochastic approach, the study incorporates uncertainties in RES generation and load demand, offering a comprehensive framework for day‐to‐day frequency stability analysis. Additionally, it presents a systematic method to ascertain the necessary inertial support for maintaining desired frequency reliability in RES‐dominated grids. The effectiveness of these methodologies is validated through a case study on a modified IEEE 39‐bus test system, demonstrating their applicability in ensuring reliable grid operation under high RES scenarios. [ABSTRACT FROM AUTHOR]

Virtual synchronous generators (VSGs) have considerable potential to be applied in renewable energy microgrid systems because they provide inertia and damping, thus improving system stability. However, the fault characteristics of renewable energy microgrids differ from those of conventional grids. Consequently, investigating the fault responses of VSGs and establishing the associated fault model would significantly enhance the fault calculation and protection mechanism design in renewable energy microgrids. This paper briefly introduces the VSG control principles and fault control strategy before establishing the corresponding transient- and steady-state VSG fault models and calculating the model parameters. For simplicity, the fault model is linearized at the steady-state estimation point and semi-decoupled for the computation of the voltage amplitude and power angle. Finally, the results from MATLAB/Simulink simulations are compared with those from the proposed fault models, and the influence of the system parameters on the model is discussed. The results demonstrate the validity, simplicity, intuitiveness, and broad applicability of our approach. [ABSTRACT FROM AUTHOR]

The growing integration of converter‐interfaced renewable energy sources (RESs) utilizing Grid‐Following (GFL) converters has displaced conventional synchronous generators (SGs) in central generation units. This shift presents challenges, including diminished system inertia, lower fault levels, and implications for system strength and network resilience. The propagation of voltage dips, particularly during disturbances like system Short Circuit (SC) faults, is adversely affected by the increased penetration of such RESs. This is attributed to the limited support capability of these sources and their distinct SC response compared to SGs. In response to these challenges, Grid‐Forming (GFM) converters emerge as a promising technology equipped with advanced functionalities that emulate SG operation. Consequently, they hold potential for mitigating the effects of voltage dip propagation in renewable‐rich power systems. This study aims to assess the impact of employing GFM converters in renewable‐rich power systems on voltage dip propagation across the network. The authors' investigation begins by examining the SC response of GFM converters and comparing it with the responses of traditional GFL converters and SGs. The paper proceeds to analyze voltage dip propagation, considering various penetration scenarios involving RESs based on GFL and GFM converters. The IEEE 9‐BUS test system, implemented in the DIgSILENT PowerFactory software, serves as the basis for these evaluations. Through extensive simulations and analysis, the authors' research provides valuable insights into the effectiveness of GFM converters in enhancing the network's response to voltage dips. [ABSTRACT FROM AUTHOR]

Introduction: Virtual Synchronous Generators (VSGs) are used in Voltage Source Converter-based Multi-Terminal High-Voltage Direct Current (VSC-MTDC) systems to enhance power system stability. However, the MTDC framework can lead to instability due to reduced inertia in certain grid areas, especially during load switching at VSC stations. This instability is exacerbated by untimely adjustments of the VSG's power setpoint, leading to voltage and frequency oscillations. Methods: This study introduces a cooperative control approach for the DC voltage of the VSG, employing a consensus algorithm and Model Predictive Control (MPC). This method aims to achieve incremental power for the VSG and provide interactive power commands for both the grid side and the wind farm side. The consensus algorithm ensures coherent system adjustments, while the MPC algorithm tracks DC-side voltage changes in real time. Results: The application of this cooperative control approach significantly enhances DC voltage regulation performance. It effectively reduces the extent of frequency drops and mitigates secondary frequency drop (SFD) issues, particularly those arising from the use of wind farms for frequency regulation and the associated speed recovery in wind turbine units. Discussion: The increase in supplemental power effectively utilizes the energy stored in DC-side capacitors for power balance regulation and introduces additional inertial power into the system. Electromagnetic transient simulations have confirmed the effectiveness of the Consensus MPC-VSG method, demonstrating its ability to optimize the dynamic performance of VSC-MTDC systems and promote stability in DC voltage and frequency. Conclusion: The findings suggest that employing the Consensus MPC-VSG method offers a promising solution for enhancing the stability and operational efficiency of VSC-MTDC systems, addressing the challenges posed by the inherent segmentation of the grid and the integration of renewable energy sources like wind farms. [ABSTRACT FROM AUTHOR]

The growing integration of renewable energy sources, especially offshore wind (OSW), is introducing frequency stability challenges to electric power grids. This paper presents a novel hybrid deloading control strategy that enables modular multilevel converter (MMC)-based wind energy conversion systems (WECSs) to actively contribute to grid frequency regulation. This research investigates a permanent-magnet synchronous generator (PMSG)-based direct-drive configuration, sourced from the International Energy Agency's (IEA's) 15 MW reference turbine model. Specifically, phase-locked loop (PLL)-free grid-forming (GFM) control is employed via the grid-side converter (GSC), and DC-link voltage control is realized through the machine-side converter (MSC), both of which boost the energy support for the integrated AC grid's frequency stability. This control strategy combines the benefits of over-speeding and pitch control modes, facilitating smooth transitions between different modes based on real-time wind speed measurements. In addition, the practical challenges of MMCs, such as circulating currents and capacitor voltage imbalances, are addressed. Numerical simulations under varying wind speeds and loading conditions validate the enhanced frequency regulation capability of the proposed approach. [ABSTRACT FROM AUTHOR]

The dwindling inertia of the power system due to the incorporation of renewable energy sources is a vital concern. This is the genesis of the frequency volatility in a system. A non-linear controller formulated on fuzzy logic has been developed for mimicking the operation of a synchronous generator. This non-linear controller is proficient in utilizing the energy present in the rotating blades of the wind turbine and nourishing the requisite quantity of inertia in the system ensuring the alleviation of the frequency variation issues. The system's improved behavior is evaluated with this innovative controller in comparison with a traditional PD/PID controller for various transients such as sudden addition, deletion of large loads, and faults. [ABSTRACT FROM AUTHOR]

Maintenance of transient stability is important for the stable operation of power systems. However, as a large amount of renewable energy sources are concerned that the transient stability deteriorates. Excitation control systems have been widely used to improve the transient stability. The defect is that only the synchronous generator (SG) near the fault location changes the excitation voltage so much immediately after the fault. In this study, we propose a novel excitation control method based on an event‐based wide‐area emergency control system. In this method, the SGs that are distant from the fault location play a role to mitigate the first swing as well as the SGs near the fault. The effectiveness of the proposed method is verified demonstrated by numerical simulation for a multi‐machine test system [ABSTRACT FROM AUTHOR]

As the world grapples with the energy crisis, integrating renewable energy sources into the power grid has become increasingly crucial. Microgrids have emerged as a vital solution to this challenge. However, the reliance on renewable energy sources in microgrids often leads to low inertia. Renewable energy sources interfaced with the network through interlinking converters lack the inertia of conventional synchronous generators, and hence, need to provide frequency support through virtual inertia techniques. This paper presents a new control algorithm that utilizes the reinforcement learning agents Twin Delayed Deep Deterministic Policy Gradient (TD3) and Deep Deterministic Policy Gradient (DDPG) to support the frequency in low-inertia microgrids. The RL agents are trained using the system-linearized model and then extended to the nonlinear model to reduce the computational burden. The proposed system consists of an AC–DC microgrid comprising a renewable energy source on the DC microgrid, along with constant and resistive loads. On the AC microgrid side, a synchronous generator is utilized to represent the low inertia of the grid, which is accompanied by dynamic and static loads. The model of the system is developed and verified using Matlab/Simulink and the reinforcement learning toolbox. The system performance with the proposed AI-based methods is compared to conventional low-pass and high-pass filter (LPF and HPF) controllers. [ABSTRACT FROM AUTHOR]

The complexity of modern power grids, caused by integrating renewable energy sources, especially inverter-based resources, presents a significant challenge to grid operation and planning, since linear models are unable to capture the complex nonlinear dynamics of power systems with coupled muti-scale dynamics, and it necessitate an alternative approach utilizing more advanced and data-driven algorithms to improve modeling accuracy and system optimization. This study employs the sparse identification of nonlinear dynamics method by leveraging compressed sensing and sparse modeling principles, offering robustness and the potential for generalization, allowing for identifying key dynamical features with relatively few measurements, and providing deeper theoretical understanding in the field of power system analysis. Taking advantage of the this method in recognizing the active terms (first and high order) in the system's governing equation, this paper also introduces the novel Volterra-based nonlinearity index to characterize system-level nonlinearity. The distinction of dynamics into first-order linearizable terms, second-order nonlinear dynamics, and third-order noise is adopted to clearly show the intricacy of power systems. The findings demonstrate a fundamental shift in system dynamics as power sources transit to inverter-based resources, revealing system-level (second-order) nonlinearity compared to module-level (first order) nonlinearity in conventional synchronous generators. The proposed index quantifies nonlinear-to-linear relationships, enriching our comprehension of power system behavior and offering a tool for distinguishing between different nonlinearities and visualizing their distinct patterns through the profile of the proposed index. [ABSTRACT FROM AUTHOR]

A hybrid microgrid is an efficient technique to integrate renewable energy resources and allow energy exchange between ac and dc subgrids. Pf and QV droop controls are commonly employed in microgrid to deliver power demands while preserving voltage and frequency restrictions via interlinking converter (IC). When a microgrid is powered by renewable energy sources, due to the prevalence of impedance conflict traditional droop techniques offer an inappropriate response in power sharing. This study employs a predictive-based control scheme to ensure appropriate power sharing between both subgrids in the event of imbalancing on either side. Photovoltaic systems, battery storage, and a synchronous generator powered by wind turbines constitute a microgrid, which is connected via an interlinking converter. The MPC MPPT-based control approach dynamically dispatches power generated by wind and solar energy sources to the loads connected throughout the hybrid microgrid. The proposed control technique maintains power exchange between hybrid microgrids within an acceptable range, according to simulation and experimental results. [ABSTRACT FROM AUTHOR]

This research investigates the impact of renewable energy integration on blinder-based Out-Of-Step (OOS) relays, which protect synchronous generators from unstable power swings. Challenges arise in distinguishing stable and unstable power swings due to fault ride-through (FRT), control operation, and weak inertia of renewable sources. Modified blinder-based OOS relays are analyzed in MATLAB using a modified Kundur two-area system. Findings show that high renewable energy penetration increases the likelihood of blinder-based relay failures during transient and small-signal stability incidents. The study also explores the effects of power swings on neighboring and remote OOS relays. Additionally, it examines the interaction between synchronous generators and renewable sources, and their impact on system stability during FRT. Modifications to single and double blinder-based OOS relays and their synchronization are proposed. The study concludes that the modified relay protection functions as inoperable for stable swings and operable for unstable swings, enhancing overall relay performance. [ABSTRACT FROM AUTHOR]

In recent years, the wind conversion system (WCS) sector has witnessed a notable surge in the recognition of robust control methodologies. This paper undertakes a thorough investigation into a resilient control system customized for a self-contained WCS, seamlessly integrating a hybrid excitation synchronous generator (HESG) linked to an independent load during the crucial Maximum Power Point Tracking (MPPT) phase. The motivation for this study lies in the growing integration of HESG technology within WCS frameworks. Addressing a vital gap in prior research, which often focused on the structural intricacies of HESG while neglecting their operational efficacy, this work aims to rectify this imbalance. Traditional control systems have limitations for WCS applications. In particular, proportional-integral (PI) controllers struggle with power quality and system performance. In this context, our research presents a MATLAB-Simulink-based equivalent model of WCS that has been rigorously developed. A novel control strategy based on Backstepping Control (BSC) is proposed as a countermeasure to existing challenges. This method not only improves WCS control efficiency but also demonstrates its proficiency in optimizing MPPT. The simulations indicate that the suggested control system outperforms the PI system regarding power fluctuations, response time, overshoot, and durability. This result demonstrates its potential to improve the effectiveness of renewable energy production. [ABSTRACT FROM AUTHOR]