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Off-grid wind energy systems play a pivotal role in providing clean and sustainable power to remote areas. However, the intermittent nature of wind and the absence of grid connectivity pose significant challenges to maintaining consistent power quality. The wind energy conversion system plays a central role in tapping renewable energy from wind sources. Operational parameters such as rotor and stator currents, output voltages of rectifiers and converters, and grid phase voltage variations are crucial for stable power generation and grid integration. Additionally, optimizing power conversion output through voltage gain analysis in boost converters is essential. Moreover, ensuring electricity quality via total harmonic distortion reduction in inverters is vital for grid compatibility. Goal. Enhancing the power quality of grid-integrated wind energy conversion systems. Methods. The proposed topology is implemented in MATLAB/Simulink with optimized control strategies for enhancing power quality in off-grid wind energy systems. Results. Control strategies with a grid-connected wind energy conversion system yields substantial improvements in power quality. This includes effectively mitigating voltage fluctuations and harmonics, resulting in smoother operation and reduced disturbances on the grid. Practical value. The proposed topology has proven to be extremely useful for off grid-integrated wind system. References 18, table 1, figures 11. [ABSTRACT FROM AUTHOR]

The multi-level inverter (MLI) plays an emergent role in high and medium-power applications. Due to the numerous advantages like lower power loss, switching loss and harmonics, the MLI is used in various applications. The major drawbacks of MLI are a higher number of switches and complex modulation strategies, thus increasing the voltage stress. Therefore, this paper proposed a novel single-phase cascaded 51-level inverter topology with fewer switches and DC sources to improve system performance. In this proposed topology, 8 IGBT switches along with 2 DC voltage sources are considered for producing 51 levels of voltage. This 51-level inverter is tuned with the help of an EPDB controller, which is a combination of Emperor Penguin Optimization (EPO) and Deep Belief Network (DBN). The EPO is used to optimize the DBN procedure to handle the MLI switches easily. Thus, it generates low harmonics voltage and error-free output voltage. The proposed inverter topology is compared with existing inverter topologies regarding the number of voltage sources, switches, and total harmonics distortion (THD). The comparative analysis demonstrates that the suggested inverter topology provides higher voltages, thereby reducing the THD of voltage to 1.17% and current to 0.10%, which are relatively lower than the existing inverter topologies; moreover, the efficiency of the proposed converter is 99.18%. [ABSTRACT FROM AUTHOR]

This manuscript proposes a hybrid method for drive control using a multilevel inverter (MLI) for electric vehicle (EV) applications. The proposed technique is the joint execution of spiking neural network (SNN), and sand cat swarm optimization (SCSO), hence it is named as SCSO-SNN technique. The primary goal of the proposed technique is to improve the speed tracking performance and, energy efficiency and lessen the torque ripple of the EV. The set of control signals is generated by SCSO and the SNN is used to forecast the optimal control signal of the cascaded multilevel inverter (CMLI). The proposed technique is implemented in the MATLAB software and is evaluated their performance with various present methods. The results show that the proposed method can achieve better performance than current techniques based on speed tracking, energy efficiency, and torque ripple. The proposed method enhanced the total efficiency of the system (96%) and reduced the torque ripple (0.5%) when contrasted with current techniques like Genetic Algorithm (GA), Spotted Hyena Optimizer (SHO), Particle Swarm Optimization (PSO). The proposed method shows a mean of 1.269, a median of 1.212, and a standard deviation of 0.015, indicating high stability and consistency. It also demonstrates lower switching losses (0.159 W) and conduction losses (0.370 W) compared to existing methods, underscoring its superior energy efficiency and effectiveness. [ABSTRACT FROM AUTHOR]

The large-scale integration of renewable energy sources and power electronic devices has led to increasingly dispersed and networked characteristics of power quality disturbances in distribution systems. Traditional control devices, limited by their fixed-point control, no longer meet the development needs of modern distribution systems. Considering the distribution and structural characteristics of the current new-type sources and loads, a multifunctional inverter power quality coordinated control strategy based on comprehensive evaluation is proposed. This strategy aims to achieve power quality coordinated control by utilizing optimal compensation capacity while the grid-connected inverter provides active power output. Firstly, the traditional ipiq power quality detection method is analyzed and improved to enable detection of harmonics, reactive power, and three-phase imbalance currents in single-phase systems or threephase four-wire systems. Secondly, in the power quality assessment, a balanced algorithm is employed to obtain the comprehensive evaluation index of power quality, thereby improving the deficiencies of single-weight evaluation. Next, to ensure the grid-connected inverter achieves optimal power quality coordinated control with minimal compensation capacity, an optimization compensation function is established between compensation capacity and comprehensive power quality index. This function is optimized using non-dominated sorting genetic algorithm to enhance equipment utilization and system economy. Finally, the feasibility and effectiveness of the proposed method are validated through simulations, demonstrating the achievement of optimal capacity configuration for power quality coordinated control while ensuring active power output by the grid-connected inverter. [ABSTRACT FROM AUTHOR]

A lot of previous studies have shown a great interest in connecting photovoltaic (PV) arrays to electric power grids. A Maximum Power Point Tracker (MPPT) controlled 100 kW PV array to boost its power that feeds the grid with the help of a three-level inverter. This paper investigated the effects of open-circuit faults of three-level inverter IGBT switches on the performance of the PV array system. This paper proposes a new diagnostic method called the Double Threshold-Trigonometric Coordinates (DT-TC) that relies on the double threshold technique and the trigonometric coordinates, respectively, for early detection and the precise location of open-circuit faults. To the best knowledge of the authors, two simultaneous open-circuit faults were not considered in the previous studies. The obtained simulation results prove the great success of the proposed diagnosis method even under noticeable changes in irradiation, temperature, and the number of PV array connected in series and in parallel. In this study, the reconfigurable fault-tolerant inverter was included to ensure the perfect continuity of the PV array system and its recovery in an extremely very short time up to 7 ms. [ABSTRACT FROM AUTHOR]

Summary: LCL‐type grid‐connected inverters have seen extensive use of the passivity‐based control (PBC) system. However, traditional PBC systems rarely take time delay into account while designing the system or doing a stability study. Therefore, utilizing Lyapunov's criterion to conclude that the system is stable is not accurate. The analysis revealed that the differential terms of PBC loops with the Euler–Lagrange (EL) mathematical model could induce instability considered control delay for LCL‐type grid‐connected inverter system. Compared with traditional EL‐PBC method, this paper proposed a reconstructed EL‐PBC scheme by properly optimizing the noise term. Then, the equivalent output impedance of the grid‐connected inverter system with proposed controller is analyzed with frequency domain passivity theory. The controller parameters are also optimized to ensure both the internal stability of LCL‐type grid‐connected inverter and the risk of interactive resonance in complex weak and nonideal grid. Results from simulation and experimentation support the modified control structure's efficacy and performance. [ABSTRACT FROM AUTHOR]

Summary: Grid‐forming (GFM) inverters offer stable frequency support for microgrid systems, even in the absence of synchronous generators. However, the GFM inverters have low inertia and vulnerability to system uncertainties and external disturbances. The conventional dual‐loop proportional integral (PI) control strategy, while widely used for its simplicity and robustness, suffers from poor dynamic performance. Motivated by this, this paper presents an observer‐based residual‐driven dynamic compensation (RDDC) strategy based on the coprime factorization technic and the Youla parameterization theory to achieve the primary control of the GFM inverter. The observer‐based RDDC strategy comprises four components: a PI controller for tracking control, a linear quadratic regulator (LQR) controller for dynamic adjustment, a residual generator based on the Kalman filter for state estimation and residual generation, and a residual compensation controller designed using model matching theory and solved through linear matrix inequality (LMI) methods for disturbance suppression. Simulation and experiment results consistently demonstrate that the observer‐based RDDC strategy ensures system robustness, enhances the dynamic and steady‐state performance of the GFM inverter system, and strengthens the ability of the GFM inverter to suppress disturbances. [ABSTRACT FROM AUTHOR]

The permanent magnet synchronous motor (PMSM) avoids commutation-related torque ripples and produces smooth torque. Its great handling capacity and better efficiency make it an excellent choice for high-demand applications. A typical PM motor drive fed with pulse width-modulated voltages may cause the motor insulation to break down if rapid voltages (dv/dt) occur across the motor terminals. Applying variable voltage with low dv/dt and implementing multiple inverter topology can solve this issue. Multilevel converters have minimal switching losses, better power quality and the ability to operate at both fundamental and higher switching frequencies. In this study, a three phase stacked multilevel inverter-based FOC driven PMSM drive design is proposed. Here, the neutral point is a capacitor intermediate point on DC side, where current is naturally balanced throughout a switching cycle. This makes it possible to use downstream batteries and even lower voltage equipment, greatly increasing efficiency, improved performance and smother control at low speed. Therefore, direct-battery-driven electric vehicles will be able to use this. A 33 level inverter-based PMSM drive was used to implement the FOC, and the simulation results were used to validate it. The Matlab/Simulink tool is used to simulate the entire system. [ABSTRACT FROM AUTHOR]

This study presents an approach for robust current and power control for a three‐phase grid‐connected inverter set up with an L‐filter that operates under an unbalanced AC grid‐voltage source. This control method consists of two paralleled current control for the positive and negative sequences to accomplish one of three selective control targets: a) supplying balanced three‐phase current; b) supplying non‐oscillated real power; and c) supplying non‐oscillated imaginary power to the AC grid for a given reference value utilizing the identical control gains. The real and imaginary power references, together with the measured grid voltages, are used in the computation of the reference current for each control target. In addition, the proposed dual‐current control system has a control law that comprises state feedback to offer stability and an integral effect to get rid of the offset error in the dq‐frame. To reduce settling time under uncertain system conditions, an optimization problem based on linear matrix inequalities is solved to determine a set of robust stabilizing gains. Simulation and experimental results using a TMS320F28377D digital signal processor validate the proposed control performance under three control targets. [ABSTRACT FROM AUTHOR]

The system performance of grid-connected photovoltaic (PV) has a serious impact on the grid stability. To improve the control performance and shorten the convergence time, a predefined-time controller based on backstepping technology and dynamic surface control is formulated for the inverter in the grid-connected photovoltaic. The time-varying tuning functions are introduced into state-tracking errors to realize the predefined-time control effect. To address the “computational explosion problem” in the design process of backstepping control, dynamic surface control is adopted to avoid the analytical calculations of virtual control. The disturbances of the PV system are estimated and compensated by adaptive laws. The control parameters are chosen and the global stability of the closed-loop is ensured by Lyapunov conditions. Simulation results confirm the effectiveness of the proposed controller and ensure the predefined time control in the photovoltaic inverter. [ABSTRACT FROM AUTHOR]

In this article, the authors present a new competitive Packed-U-cell and neutral point clamped (PUC-NPC) 9-level converter that utilizes a small number of power switches and passive components. Only seven switches are added to a single DC source. However, the proposed converter takes benefits of the neutral point clamped (NPC) converter's capability to connect capacitors in series, all with a simple control that enables the algorithm associated to the proposed inverter operate correctly in an open loop operation. A technique of pulse width modulation (PWM) is employed to maintain capacitor voltage at desired values. The proposed inverter produces an almost sinusoidal waveform output voltage, as result, a perfectly sinusoidal charge current with minimal impact on the economy and energy consumption are optioned. The converter has been integrated with a photovoltaic system to minimize its impact on the electricity supply and enhance energy efficiency. In order to take a maximum power from the photovoltaic panel, authors employ a maximum power point tracking (MPPT) technique based on disturbance and observe (P and O). When combined with the proposed control technique, it offers a competitive system suitable for standalone use or as an energy source, eliminating the need for PI regulators or additional investments. The proposed 9-level converter has been validated through simulation, utilizing the MATLAB Simulink environment to model the proposed system. Dynamics of this later were verified by changing the load charge. [ABSTRACT FROM AUTHOR]

This paper introduces a novel three‐phase grid‐tied multilevel inverter (MLI) topology that employs a basic unit per phase, yielding a symmetrical configuration capable of generating five‐level output voltage and an asymmetrical configuration producing seven‐level and nine‐level output voltages. The generalization of the proposed MLI is presented in terms of the number of modules (M) and output levels (L). A comprehensive comparative analysis of the proposed MLI topology against existing configurations is presented for both symmetric and asymmetric cases. The switching devices in the MLI are controlled using the in‐phase disposition level shift PWM (IPD‐LSPWM) technique. The synchronization of the grid‐tied MLI is addressed by considering the uncertainties in grid and load parameters at the point of common coupling (PCC). To achieve synchronization, a PLL‐less grid voltage‐ modulated direct power control (GVM‐DPC) technique is implemented. To mitigate the delay associated with PLL, a GVM‐DPC based on the stationary reference frame (SRF) is applied. This paper also includes mathematical modelling of GVM‐DPC without PLL and the design of an LCL filter. A simulation model of a 15‐kVA, three‐phase, nine‐level grid‐tied MLI is developed in MATLAB/Simulink and tested under both steady‐state and dynamic conditions. The proposed controller's performance is evaluated under the load variations and sudden changes in available power from the distributed generator (DG). Robustness is tested under adverse conditions such as voltage sag/swell at the PCC. Furthermore, the system is implemented in the OPAL‐RT OP4510 real‐time simulator, and the results are validated to confirm the effectiveness and robustness of the proposed grid‐tied MLI. [ABSTRACT FROM AUTHOR]

A three‐level neutral point clamped (3L‐NPC) voltage source inverter (VSI) topology can be advantageous in electric vehicles with a high DC‐link voltage and a high switching frequency. A bulky DC‐link capacitor is not an option; thus, the DC‐link capacitor's sizing considering the traction system characteristics is an important design step. This paper investigates how the DC‐link capacitor size of a 3L‐NPC VSI gets affected by the combination of the interdependent characteristics of an electric drive, such as its power factor, modulation index, current, and fundamental frequency, with the effects of the modulation methods. Five pulse width modulation (PWM) methods, of which three of them have an active neutral point potential control, are compared in terms of their neutral point potential (NPP) oscillations. Then, the size of the DC‐link capacitor is determined for each PWM method so that the NPP ripple is kept under desired limits at all operating conditions. It is shown that both the modulation technique and the electric machine characteristics influence the capacitor size. For example, electric machine design modifications can introduce more than a 30% reduction in capacitor size. Finally, DC‐link and NPP oscillations with different PWM methods are experimentally validated in a scaled‐down 3L‐NPC inverter. [ABSTRACT FROM AUTHOR]

Z-source inverters are used in controller applications, which offer higher performance than the buck-boost converter. This work presents the Improved Embedded Z (IEZ)-source inverter used for the impedance network. The Z-source inverter includes the switching topologies, so the double inductor is added to the EZ source inverter circuit. IEZ source inverter manages the Total Harmonic Distortion (THD), and the PID controller controls the inverter voltage. The Social Ski Driver (SSD) Optimization algorithm is used to tune the parameters of the PID controller. The harmonic content of the Z-source inverter is reduced by the carrier based sinusoidal Pulse Width Modulation (SPWM) technique. The Improved Embedded Z-source Inverter (IE-ZSI) is utilized to apply a grid-connected system. The inverters receive the power from the DC voltage and supply the grid-connected load with controllable voltage. The proposed work is implemented in the platform MATLAB/SIMULINK to evaluate the performance of the voltage across the capacitor, the voltage across the inductor, grid current and grid voltage. Inverter DC link voltage performance was compared to conventional Z-source inverters and embedded Z-source inverters. The proposed work achieved 1.52% THD compared with existing techniques. [ABSTRACT FROM AUTHOR]

The main contribution of this paper is to present a simple algorithm that theoretically and numerically assesses the switching angles of an inverter operated with the SPWM technique. This technique is the most widely used for eliminating harmonics in DC-AC converters for powering motors, renewable energy applications, household appliances, etc. Unlike conventional implementations of the SPWM technique based on the analog or digital comparison of a sinusoidal signal with a triangular signal, this paper mathematically performs this comparison. It proposes a simple solution to solve the transcendental equations arising from the mathematical analysis numerically. The technique is validated by calculating the total harmonic distortion (THD) of the generated signal theoretically and numerically, and the results indicate that the calculated angles produce the same distribution of harmonics calculated analytically and numerically. The algorithm is limited to single-phase inverters with unipolar SPWM. [ABSTRACT FROM AUTHOR]

In weak grid, feedforward of grid voltage control is widely used to effectively suppress grid-side current distortion of inverters caused by harmonics in point of common coupling (PCC) voltage. However, due to its introduction of a positive feedback loop related to the grid impedance, it results in a significant reduction in the system phase margin. In view of this, in this paper, the output impedance of a three-phase LCL grid-connected inverter under a quasi-proportional resonant (QPR) controller is first modeled. Instead of the traditional grid voltage feedforward control strategy, a band-pass filter is added to the grid voltage feedforward channel. Secondly, a multi-objective constraint method is proposed to make improvements to the feedforward function. Then, a multi-objective constraint function is established with the constraints of base-wave current tracking performance, system stability margin, and low-frequency amplitude, and the feasibility of its function optimization design method is verified. Theoretical analysis shows that the optimized grid voltage feedforward control strategy can effectively reshape the phase characteristics of the system output impedance, which greatly broadens the adaptation range of the system to the grid impedance. Finally, the effectiveness of the proposed control strategy is verified by building a semi-physical simulation experimental platform based on RT-LAB OP4510. [ABSTRACT FROM AUTHOR]

The increasing proportion of new energy in the power system leads to a decrease in system inertia and weakens the frequency stability of the system. The use of grid-forming (GFM) control for inverters is an effective method to improve frequency stability in new energy generation systems. Due to uncertain disturbances in microgrids, it can cause changes in system frequency. A control strategy for linear active disturbance rejection control combined with model information (LADRC-MI) is proposed in this manuscript. In this method, the inertia level and damping of the system are improved by using virtual synchronous generator (VSG)-based GFM control. Then, the obtained part of the model information is written into the coefficient matrix of the linear extended state observer. The LADRC-MI is constructed to improve the immunity of the controller. Finally, the effectiveness of the strategy in improving the immunity and frequency stability of the converter is analyzed and verified. [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]

A multi‐inverter‐fed power system is susceptible to small‐signal instability owing to weak grid influence. This study proposes a black‐box method for small‐signal stability analysis of a multi‐inverter‐fed power system based on Bode diagrams. Not only did it consider the technical confidentiality on the engineering site, but it also took into account the presence of right‐half‐plane (RHP) pole in the aggregated impedance, achieving Nyquist circle acquisition through Bode diagrams. The stability analysis process is thus more accurate, intuitive, and convenient. First, black‐box impedance fitting for a single grid‐connected inverter and impedance aggregation for a multi‐inverter‐fed power system are discussed. Second, the principle of the proposed method is elaborated. Using the Bode diagram, the number of RHP poles of the aggregated impedance and actual number of circles for Nyquist curves are identified. Third, a multi‐inverter‐fed power system is constructed, and the effectiveness of the proposed method is verified using case analysis and hardware‐in‐the‐loop real‐time experiments based on RT‐LAB. Finally, the advantages of the proposed method are revealed by comparing it to the IF method. [ABSTRACT FROM AUTHOR]

This paper proposes a diagnostic and fault-tolerant method for an open-fault condition in dual inverters with open-end winding interior permanent magnet synchronous motors (OEW-IPMSMs). Certain switch pairs show similar behavior in the output current in an open-fault condition due to the structural characteristics of the two-level dual inverter. This work presents a method for detecting open-fault conditions and ensuring a fault-tolerant operation. The proposed method is applied in dual inverters with isolated voltage sources for driving OEW-IPMSM. In the event of an open-fault condition, a pair of switches containing the faulty switch is identified based on the stator current. Subsequently, the switch with the open-fault condition is determined, and fault-tolerant control for a faulty switch is immediately performed through a single-mode operation using zero-voltage vectors. The effectiveness of the proposed detection and tolerant control method is confirmed through simulation and experimental results. [ABSTRACT FROM AUTHOR]

A self-compensating control strategy for harmonic parameters based on the crown porcupine optimization algorithm is proposed for the single-phase rectifier and two-phase inverter operation mode of the bidirectional converter. In order to improve the response speed of the inverter voltage, the instantaneous expressions of the phase angle coefficient and amplitude coefficient of the dc-side voltage doubling fluctuation are derived, and the third harmonic is calculated based on the crown porcupine optimization algorithm according to the Proportional Integral (PI) + Quasi-Proportional Resonance (QPR) double closed-loop control method and injected into the input voltage of the inverter side to offset the influence of the bus-doubling fluctuation on the output voltage of the two-phase inverters of B and C so that the total harmonic content of the two-phase output voltages of the two-phase inverters of B and C can be reduced. The total harmonic content of the B and C inverter output voltages is reduced. The effective control of the control method for single-phase rectifier two-phase inverter mode is verified through simulation. Finally, the effectiveness of the control strategy is verified by experimenting with a 15 kW LCL-type bi-directional converter prototype. [ABSTRACT FROM AUTHOR]

Cascaded H-bridge inverters, which belong to strongly nonlinear time-varying system with complex dynamics, have been widely used in high-voltage and high-power engineering fields. In this paper, a carrier phase-shifted sinusoidal pulse-width modulation cascaded H-bridge inverter is taken as an example with piecewise analysis to establish the discrete iterative mathematical model. Furthermore, the nonlinear dynamic behavior of this inverter system is investigated using folding diagrams, spectrum diagrams, bifurcation diagrams, Lyapunov exponents, etc. We find that this inverter can exhibit multiperiod bifurcation, tangential bifurcation and paroxysmal chaos within certain ranges of control coefficients and other circuit parameters, which will influence the system's stability seriously. On the basis of this discovery, the sinusoidal time-delay feedback control method is proposed. The difference between the load current of the controlled object and its own delay is used to form a feedback term, which is then fed into the sine function and proportional link to obtain the control term. Moreover, the Jacobian matrix of this feedback inverter system is derived, and the constraints on the feedback control coefficient are obtained based on the Jury criterion. Simulation results have verified the effectiveness of such a sinusoidal time-delay feedback control method, which can improve the stability and anti-interference of the system. The research can be used to provide some reference and guidance for the circuit design, debugging and control of cascaded H-bridge inverters. [ABSTRACT FROM AUTHOR]

Photovoltaic inverters are widely utilized in microgrid systems working as the key equipment for converting solar energy into usable electricity. This paper presents a fuzzy sliding mode control (FSMC) method for the photovoltaic inverter in a microgrid. The inverter module uses voltage control to achieve stable AC output voltage. Moreover, to deal with system uncertainty and non-linearity in the photovoltaic inverter, a fuzzy controller was designed to realize real-time adaptation of the gains of the constant term and the reaching term in the sliding mode control law, which serves as a compensating controller for traditional sliding mode control. The gains of the exponential reaching law can be adjusted according to the system state instead of fixed gains, which can effectively reduce the chattering phenomenon and improve the robustness of the photovoltaic microgrid. Finally, the Lyapunov stability theory was used to ensure the stability of the entire control system, achieving a high-performance independent power supply for loads in a microgrid. Simulation results show that the designed control system is more robust to load disturbances and has superior dynamic performance. [ABSTRACT FROM AUTHOR]

In recent years, with depletion of fossil fuel and exponential increase of power demand meeting the customer needs become a significant challenge for service providers. In this paper, Internet of Things (IoT) based bidirectional converter (BC) is designed which enhances the power electronics converters into the next platforms. This bidirectional converter is built with wireless connectivity. Also, the cluster is built in the series of diverse downwind distances (i.e., between the turbines) can be tested with minimum rearrangement effort. In IoT equipped bidirectional converter farm is evaluated in offline mode by collecting the data remotely. The proposed BC is able to operate in renewable energy (like photovoltaic, wind, etc.) based standalone systems. This BC converter is proposed to transfer power from grid/ renewable energy systems to a battery storage system (BSS) as well as BSS to grid power transfer. The proposed work of cascade topology allows maintaining input voltage as well as output voltage level. During discharging, the energy from a battery pack is returned to the grid where the dc link bus is interconnected with electric traction inverter. Input and output voltage values of the converter are used to fix the reference voltage subject to the power demand requirement. Artificial neural networks are used to regulate the voltage of dc link capacitor. The performance of the proposed BC regarding voltage gain, efficiency, and flexible application have been analysed using MATLAB simulation and also with experimental studies. [ABSTRACT FROM AUTHOR]

The grid-feeding inverter is the most popular choice for implementing a distributed generator (DG) in a photovoltaic (PV) system. Its role is to deliver active power with zero reactive power while connected to the grid. In most cases, the inverter is disconnected as soon as voltage sag disturbances occur, an operation that is known as an islanding mode. Recently, grid code regulations have been upgraded, allowing the inverter to remain connected to the grid and inject a certain amount of reactive power during voltage sags, provided that it meets grid code requirements. However, this can result in an increase in current injection by the inverter, which may cause overcurrent and damage the inverter if it exceeds the capability of the inverter. To control peak current during voltage sag disturbances, a proposed grid-feeding inverter attempts to detect voltage sag and calculate proportional injected active and reactive power. Once the disturbance has disappeared from the system, the inverters can be restored to normal operation. Prototype experiments have validated the ability of this system to control peak current during voltage sag while protecting the inverters. [ABSTRACT FROM AUTHOR]

The H-bridge MLI has cascaded to addicted cascaded the diode with switches of lower rated power, consumption of power reactive and active. A new system is being developed to increase effectiveness of MLI (multilevel inverter). within the electricity system, to inverter is critical for DC-AC voltage conversion. MLI focuses more on Industry Needs. MLI is typically used to provide high power at high voltage applications. In comparison to inverters flying capacitors and the diode-clamped, it has the fewest components and the voltage level it same number to achieve the voltage balancing capacitors or diodes any voltage clamping. This design incorporates a multilayer inverter with a cascaded H Bridge based on a Boost circuit (BCCHB). The job of the voltage to increase the boost circuit of the multilevel inverter. Boost circuits are essential in an application of wide range, including photovoltaic and the use of fuel cells. ML Inverter with Cascaded H Bridge is a Voltage Controlled Source Inverter with the advantages of being small in size and having an output waveform that is independent of load type. A cascaded H Bridge prototype model based on a boost circuit is validated, and the results simulation has been compared with the result. [ABSTRACT FROM AUTHOR]

Summary: Grid‐connected inverter with a novel fractional‐order LLCL filter has the advantage of high grid current tracking accuracy and low total harmonic distortion without passive or active dampers, and the grid voltage full feedforward scheme is an effective method to improve the quality of grid current. However, due to the digital control delay, the suppression of the grid current harmonics is weakened, and the inverter output impedance has an additional negative phase shift, which deteriorates the stability of grid‐connected systems under weak grid. In this paper, a weighted grid voltage fractional‐order feedforward control scheme is proposed based on a quasi‐proportional resonant (QPR) controller, which introduces two weighting factors in the full feedforward path of the grid voltage and compensates the phase lag of the output impedance by designing appropriate weighting factors. Then, an improved scheme combining the QPR controller with a phase compensator is presented. As a result, the suppression ability of grid current harmonics and the adaptability to grid impedance variations are enhanced. Simulation and experimental results verify the effectiveness of the proposed grid voltage fractional‐order weighted feedforward scheme. [ABSTRACT FROM AUTHOR]

This article presents a novel 3-Φ inverter that operates from a single direct current source and is based on the idea of switched-capacitor (SC) techniques. Each phase leg of the proposed topology (PT) consists of eight switches, two capacitors, and a diode. This configuration enables the generation of seven levels (line-to-line) voltage waveforms. The proposed design has several advantages, such as the capacitors' natural balancing, the ability to boost, minimum voltage stresses on the power switches, and fewer switching components. When compared to the conventional two-stage design, single-stage dc–ac power converters with boost capabilities present an intriguing option. This paper introduces a novel boost-type inverter for use in a wide variety of applications, including rolling mills, fans, pumps, maritime appliances, mining, tractions, and more. The study explains the proposed design, principle, control mechanism, and loss analysis in great depth. The advantages of the PT have been demonstrated through comparison with recently published SC topologies. Finally, a 1550-W downscale prototype is used to experimentally verify its viability and performance, with an estimated efficiency of around 96.6%. [ABSTRACT FROM AUTHOR]

The classical model predictive control (MPC) usually aims to minimize the current error at the end of the control period. This method is equivalent to minimizing the current total harmonic distortion (THD) when the control period tends to be infinitely small. However, due to the limitations of hardware in practice, the optimization effect of current THD is not obvious. Aiming at the above problem, an improved double-vector model predictive control method is proposed for the single-phase active-neutral-point-clamped five-level (ANPC-5L) inverter. Two voltage vectors in each control cycle are used in this method to reduce the current THD by minimizing the area enclosed by the actual and reference current. In addition, a capacitor voltage control method is designed for the problem of multiple control objectives coupling in this structure. In this method, an idea of hierarchy is designed for voltage jump and switching transition limits, neutral point (NP) voltage, and flying capacitor (FC) voltage, achieving the effect of weightless factor and good dynamic and static performance. Finally, the effectiveness of the proposed method is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents development of a hardware simulator for the DC–AC inverters of electric compressors (e-compressors). In general, early-release EVs often feature a nominal battery voltage of around 400 V. However, EVs with a 400 V battery have drawbacks such as slow battery charging speeds and limited driving distances. To overcome these drawbacks, the nominal battery voltage has recently been increased from 400 V to around 800 V. Accordingly, research on electrical components applicable to EVs with an 800 V battery has been conducted. However, research on the DC–AC inverter used in the e-compressor, as a core component of an electric air conditioning system for EVs with 800 V battery, is insufficient. Therefore, the development of a hardware simulator of DC–AC inverters for the e-compressors used in EVs with an 800 V battery is proposed in this paper. The validity of the proposed hardware simulator is verified by experimental results. [ABSTRACT FROM AUTHOR]

The multi-level inverter (MLI) is more efficient due to its ability to eliminate low-order harmonics. Thus, it is widely used in renewable energy generation, electric vehicles (EVs), etc. The choice of the neutral-point clamped (NPC) converter topology as a research object is of great significance in practical engineering. However, complex modulation algorithms and neutral-point voltage unbalance are two inherent problems for such NPC inverters. In this paper, an improved multi-voltage vector model predictive control (MVV-MPC) strategy based on neighboring four voltage vector synthesis is presented for three-phase NPC inverters. The duty cycle calculation and derivation methods for the proposed method are very simple, and they were obtained through the action time of each voltage vector being inversely proportional to the value of the corresponding cost function. Moreover, the fixed switching frequency of this strategy is maintained and the current peak ripple is reduced, guaranteeing the preferred total harmonic distortion of the output waveform. Furthermore, a voltage balancing method based on zero-sequence voltage injection is utilized to achieve dynamic balancing of the midpoint voltage difference and to limit the oscillation magnitude of the midpoint voltage difference to within ± 1 V. Finally, MATLAB simulations and an HIL experimental platform are built to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The rising popularity of grid-connected multilevel inverters with photovoltaic panels underscores the importance of effective modulation and control strategies for ensuring optimal power quality. The performance of these inverters hinges significantly on modulation and control approaches, specifically addressing issues like common mode voltage, harmonics, switching loss, and dynamic response. This study introduces a novel approach to mitigate current harmonics in these inverters by employing sliding mode control. Notably, this technique achieves harmonic reduction without necessitating an increase in the switching count. The presented technique eliminates phase-locked loop, current controllers, and carrier waves, thereby easing hardware computation. Beyond computational efficiency, this approach contributes to enhanced power quality and dynamic response within the inverter system. Simulation results affirm the efficacy of the proposed method when compared to the use of the phase opposite disposition modulation combined with the current controllers. In the nominal operational mode, the proposed method reduces the current Total Harmonic Distortion (THD), the highest magnitude of individual harmonics, and the switching count by 43.6%, 73.5%, and 19.6% respectively, compared with those of the method using the phase opposite disposition modulation combined with current controllers. [ABSTRACT FROM AUTHOR]

In this paper an efficient, compact, and cheap power source design for an off-grid PV water pumping system is investigated. The proposed system consists of a PV array, battery, three-port converter (TPC), three-phase voltage source inverter, and induction motor pump. Power is extracted from PV sources during the daytime and used to charge batteries through the three-port converter, then used later to supply load during the nighttime. An intelligent MPPT method is used to obtain PV maximum power; a jellyfish optimization technique with different control algorithms is used to optimize and tune controllers' parameters among the system. Different modes for the TPC are discussed depending on PV power availability. The proposed system is simulated to assess system performance under different conditions; also the system is efficient with reduced number of components than conventional converters. A complete unified power management over PV input port, battery port, and load port has occurred for all operation modes. At all operation modes, the system has been feeding load without any unmet loads. A real case study in Al-Kharijah oasis is studied and simulation results are listed; for the Dom case DC bus ripple factor voltage percentage equals 0.8%, in the Dim case equals 3%, and in the Siso mode equals 9%. [ABSTRACT FROM AUTHOR]

This research paper introduces an innovative modulation technique for controlling a 3-level flying capacitor multilevel inverter (FCMLI), aiming to streamline the modulation process in contrast to conventional methods. The proposed simplified modulation technique paves the way for more straightforward and efficient control of multilevel inverters, enabling their widespread adoption and integration into modern power electronic systems. Through the amalgamation of sinusoidal pulse width modulation (SPWM) with a high-frequency square wave pulse, this controlling technique attains energy equilibrium across the coupling capacitor. The modulation scheme incorporates a simplified switching pattern and a decreased count of voltage references, thereby simplifying the control algorithm. [ABSTRACT FROM AUTHOR]

In this research, the performance of vanadium redox flow batteries (VRFBs) in grid-connected energy storage systems centering on frequency and power sharing using voltage source inverters was evaluated. VRFBs are increasingly promising due to their scalability and long lifespan. We explore the impact of voltage source inverters on the frequency of the power supply when there is a change in load and power sharing between the grid and VRFB through MATLAB simulations. The test system demonstrates a storage system at an 11-kV substation and considers a load profile commencing from residential and commercial consumers. The outcome of this study reveals that VRFBs provide the required power to maintain load demand. Due to fast response time, VRFBs also regulate the frequency efficiently during the change in load demand and maintaining current total harmonic distortions (THDs). This research confirms the design and operation of VRFB-based energy storage systems, contributing to resilient grid infrastructure and reliable power distribution systems. [ABSTRACT FROM AUTHOR]

This study presents the development of an adaptive fuzzy control strategy for double-star PMSM-PWM inverters used in ship electrical propulsion. The approach addresses the current and speed tracking challenges of double-star permanent magnet synchronous motors (DSPMSMs) in the presence of parametric uncertainties. Initially, a modeling technique employing a matrix transformation method is introduced, generating decoupled and independent star windings to eliminate inductive couplings, while maintaining model consistency and torque control. The precise DSPMSM model serves as the foundation for an unknown nonlinear backstepping controller, approximated directly using an adaptive fuzzy controller. Through the Lyapunov direct method, system stability is demonstrated. All signals in the closed-loop system are ensured to be uniformly ultimately bounded (UUB). The proposed control system aims for low tracking errors, while also mitigating the impact of parametric uncertainties. The effectiveness of the adaptive fuzzy nonlinear control system is validated through tests conducted in hardware-in-the-loop (HIL) simulations, utilizing the OPAL-RT platform, OP4510. [ABSTRACT FROM AUTHOR]

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]

This paper proposes an input-parallel output-series (IPOS) Si-SiC hybrid inverter with dual-frequency harmonic elimination modulation strategy. The proposed topology composed of two power conversion cells and a three-phase five column medium-frequency step-down transformer, the low-frequency power conversion cell (LFPC-C, 1 kHz) leverages strong current-carrying capacity of silicon-based devices for dealing with the system main power, and the high frequency power conversion cell (HFPC-C, 30 kHz) based on wide-band-gap semiconductor SiC devices is used to addressing the fractional harmonics compensation power. This topology combines the strong current carrying capability of Si devices with the low switching loss of SiC devices at high frequency and achieves high quality power conversion at low cost and low loss. Compared to existing "IPOP" Si-SiC hybrid inverters, this topology adopts a coupling step-down transformer on the output side of both LFPC-C and HFPCC, which can effectively reduce current stress of HFPC-C SiC devices. Additionally, a dual-frequency harmonic elimination modulation strategy based on the topology is proposed to solve the fractional harmonics caused by the LFPC-C. The paper establishes a mathematical model according to the harmonic distribution characteristics of the LFPC-C and HFPC-C, and designs the system control schedules. Building upon the derivation of the voltage ripple model and the design of hardware parameters, Si IGBT and SiC MOSFET were selected for constructing a 7.5 kW prototype for testing, and the experimental results validate the feasibility of this topology and the accuracy of theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a control strategy for grid-following inverter control and grid-forming inverter control developed for a Solar Photovoltaic (PV)–battery-integrated microgrid network. A grid-following (GFL) inverter with real and reactive power control in a solar PV-fed system is developed; it uses a Phase Lock Loop (PLL) to track the phase angle of the voltages at the PCC and adopts a vector control strategy to adjust the active and reactive currents that are injected into the power grid. The drawback of a GFL inverter is that it lacks the capability to operate independently when the utility grid is down due to outages or disturbances. The proposed grid-forming (GFM) inverter control with a virtual synchronous machine provides inertia to the grid, generates a stable grid-like voltage and frequency and enables the integration of the grid. The proposed system incorporates a battery energy storage system (BESS) which has inherent energy storage capability and is independent of geographical areas. The GFM control includes voltage and frequency control, enhanced islanding and black start capability and the maintenance of the stability of the grid-integrated system. The proposed model is validated under varying irradiance conditions, load switching, grid outages and temporary faults with fault ride-through (FRT) capability, and fast frequency response and stability are achieved. The proposed model is validated under varying irradiance conditions, load switching, grid outages and line faults incorporating fault ride-through capability in GFM-based control. The proposed controller was simulated in a 100 MW solar PV system and 60 MW BESS using the MATLAB/Simulink 2023 tool, and the experimental setup was validated in a 1 kW grid-connected system. The percentage improvement of the system frequency and voltage with FRT-capable GFM control is 69.3% and 70%, respectively, and the percentage improvement is only 3% for system frequency and 52% for grid voltage in the case of an FRT-capable GFL controller. The simulation and experimental results prove that GFM-based inverter control achieves fast frequency response, and grid stability is also ensured. [ABSTRACT FROM AUTHOR]

A novel programmed hybrid spreading spectrum modulation method to mitigate electromagnetic interference (EMI) emission and bearing current in the context of miniaturised and lightweight synchronous machine drives is proposed. The proposed method adopts the combination of conventional pulsewidth modulation (PWM) and low common mode voltage PWM. The offline look‐up table for switching frequency is acquired by analysing the root mean square voltage values at different modulation indices and angles. By adjusting the switching frequency according to this table, the spectrum can be spread into the sidebands of the switching frequency, and the harmonic spike can be suppressed. To address the challenge of increased current ripple and harmonic distortion in high torque density motors under overload conditions, a motor model that considers the cross‐saturation and slotting effect is presented. This motor model is used to derive the switching frequency correction factors, aiming to mitigate the influence of saturation and slotting effect on harmonic amplification. The proposed method is well‐suited for controlling synchronous motors using three‐phase two‐level voltage source inverters. The simulation and experimental results validate the effectiveness of the proposed method, showcasing its advantages in terms of computational complexity reduction and significant attenuation of peak EMI currents. [ABSTRACT FROM AUTHOR]

This paper presents a state‐space average model of a three‐level photovoltaic (PV) inverter to understand short‐circuit currents transient characteristics. Analytical solution of the model is also derived. The proposed model is validated with PV system controller hardware in‐loop (HIL) test method. The errors between simulation and HIL tests results under various conditions are evaluated, testifying the validity of the proposed model. With the model and analytical solution, the decaying time constants of sub‐transient and transient processes are derived, which shows that the time constants of a three‐level PV inverter are not fixed and they vary with voltage dips. The analytical expression of short‐circuit currents is also formulated. The findings from this study are essential to short‐circuit current calculations of a power grid with large‐scale PV plants, coordination of power system protections, and grid planning. [ABSTRACT FROM AUTHOR]

Summary: In many practical applications such as motor drives, the inverter is required to produce a variable output voltage within a wide range (e.g., 0.1 to 1 pu). In such cases, when the inverter operates in low modulation index (low output voltage), the harmonic distortion of the output voltage increases due to considerable reduction in the magnitude of the fundamental component. Also, the ratio of the switching losses to the output power will be high in the low modulation index. In this paper, a simple solution is proposed to overcome the problems. The principle of the proposed solution is to adjust the DC‐link voltage so that the modulation index of the inverter remains within a specific high range. Different practical ways of obtaining controlled DC‐link voltage are presented. Also, for operation of the DC‐DC converter used for DC‐link voltage control, three strategies are proposed. The proposed solution is simple, and it is very effective and feasible to implement. To the best of the authors' knowledge, the idea has not been presented in this form previously. In order to verify the proposed solution, the simulation and experimental results are presented and discussed. [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]

In a renewable-energy-penetrated power system (RPPS), inverter-based resources (IBRs) pose serious challenges to power system stability due to their completely different dynamic characteristics compared with conventional generators; thus, it is necessary to study the dynamic interactions between IBRs and power systems. Although many research efforts have been dedicated to this topic from both power electronics and power system researchers, some research from the power electronics field treats the external power system as a voltage source with an impedance, therefore ignoring the dynamic characteristics of a power system, while most of the research from the power system field applies simulation-based methods, for which it is difficult to directly interpret the interaction mechanism of IBRs and external system dynamics. Thus, none of these studies can explore the accurate dynamic interaction mechanism between IBRs and power systems, leading to performance degradation of IBR-integrated power systems. Our study takes into account the dynamic characteristics of both IBRs and the external power system, resulting in the development of a new open-loop transfer function for RPPSs. Based on this formulation, it is observed that under certain operating conditions, the dynamic interactions between the inverter and the power system help enhance IBR-penetrated power system stability compared with the case for which the external power system is controlled as a voltage source. The study also reveals how the inverter (phase-locked loop, control parameters, etc.), external power system (network strength) and penetration ratio in an IBR-penetrated power system affect the dynamic interactions between IBRs and the external power system using the proposed quantified interaction indices. [ABSTRACT FROM AUTHOR]

The world's energy demand is on the rise, leading to an increased focus on renewable energy options due to global warming and rising emissions from fossil fuels. To effectively monitor and maintain these renewable energy systems connected to electrical grids, efficient methods are needed. Early detection of PV faults is vital for enhancing the efficiency, reliability, and safety of PV systems. Thermal imaging emerges as an efficient and effective technique for inspection. On the other hand, evidence indicates that monitoring inverters within a solar energy farm reduces maintenance expenses and boosts production. Optimizing the efficiency of solar energy farms necessitates comprehensive analytics and data on every inverter, encompassing voltage, current, temperature, and power. In this study, our objective was to perform two distinct fault analyses utilizing image processing techniques with thermal images and machine learning techniques using inverter and other physical data. The results show that hotspot and bypass failures on the panels can be detected successfully using these methods. [ABSTRACT FROM AUTHOR]

This paper presents a new electric drive-reconfigured on-board charger and initial electromagnetic torque suppression method. This proposed reconfigured on-board charger does not need many components added to the original electric drive system: only a connector is needed, which is easy to add. Specifically, the inverter for propulsion is reconfigured as a buck chopper and a conduction path to match the reconfigured windings. Two of the machine phase windings serve as inductors, while the third phase winding is reutilized as a common-mode inductor. In addition, the initial charging torque is generated at the outset of the charging process, which may cause an instant shock or even rotational movement. In order to prevent vehicle movement, the reason for the charging torque and suppression method were analyzed. Further, predictive control of the model based on mutual inductance analysis was adopted, where the charging torque was directly used as a control object in the cost function. Finally, experimental performances were applied to verify the proposed reconfigured on-board charger under constant current and constant voltage charging. [ABSTRACT FROM AUTHOR]

The increasing integration of inverter based resources (IBR) in the power system has a significant multi‐faceted impact on the power system operation and stability. Various control approaches are proposed for IBRs, broadly categorized into grid‐following and grid‐forming (GFM) control strategies. While the GFL has been in operation for some time, the relatively new GFMs are rarely deployed in the IBRs. This article aims to provide an understanding of the working principles and distinguish between these two control strategies. A survey of the recent GFM control approaches is also delivered here, expanding the existing classification. It also explores the role of GFM control and its types in power system dynamics and stability like voltage, frequency etc. Practical insight into these stabilities is provided using case studies, making this review article unique in its comprehensive approach. Lacking elsewhere, the GFMs' real‐world demonstrations and their applications in several IBRs like wind farms, photovoltaic power generation stations etc., are also analyzed. Finally, the research gaps are identified, and the prospect of GFM is presented based on the system needs, informed by GFM real‐world projects. This work is a potential road map for the GFM large‐scale deployment in the decarbonized IBR‐based bulk power system. [ABSTRACT FROM AUTHOR]