This article proposes a novel switched capacitor based thirteen-level common ground (CG) type inverter topology with six times voltage boosting capability and inherent voltage balancing ability. This topology is suited for low-voltage photovoltaic (PV) systems without any intermediate voltage boosting stage. The CG feature of this inverter bypasses the PV parasitic capacitor, which results in the elimination of the leakage current. The proposed inverter uses twelve switches, two diodes, and three capacitors to synthesize thirteen levels in the output voltage with six times voltage gain. The pulse width modulation (PWM) scheme, along with the developed switching states, charges and discharges the capacitors periodically, which ensures a stable and balanced voltage across the capacitors. The circuit description of the proposed inverter, switching states, PWM scheme, grid-tied control scheme, loss analysis, and design guidelines for switched capacitors are discussed in detail. A detailed comparative assessment of the proposed topology is carried out with the existing state-of-the-art CG type topologies, which highlights the merit of the proposed inverter topology. The operation and control of the proposed inverter topology are validated through extensive experimental results.

The distribution grid is under major transformation due to the increasing dependency on renewable energy resources (RESs) and electric vehicle (EV) charging stations. For accommodating such sources and loads in an existing ac distribution system without violating the voltage and current quality limits, various strategies, such as modifying the control methodologies and structural reconfiguration of the grids, are identified as suitable options. The power electronic converters play a significant role in integrating these features to the distribution grid. A unified power quality conditioner (UPQC) is a preferred choice to control the quality of both currents and voltages. In this article, the operation of a meshed hybrid microgrid is realized using UPQC. The dc link of UPQC is used to form a low voltage dc (LVdc) line. This LVdc line is connected parallel to the low voltage ac (LVac) lines. The loads and distribution generation units are integrated to ac and dc lines using power electronic converters. The improved performance during adverse operating conditions shows the superior reliability of the proposed system. In addition, the analysis verifies the enhanced capability of the proposed system in accommodating new dc loads to the existing system. Both simulation and experimental results are demonstrated to evaluate the performance of the proposed system.

With increased proliferation of renewable energy sources (RESs), maximizing energy extraction while sustaining power quality of the grid is a major challenge in microgrids (MGs). This article presents a novel application of dual voltage source inverter (DVSI) topology to facilitate low voltage ride-through (LVRT) under varying grid voltage conditions. It consists of two inverters that individually deliver active power from RESs to the grid and provide reactive and harmonic load current compensation. A modified dual second-order generalized integrator (DSOGI)-based quasi-type-1 phase-locked loop (QTI-PLL) is introduced to enhance inverter control under grid disturbances such as harmonic distortion, unbalance, and dc offset. A power management strategy is proposed for the DVSI scheme, integrating RES and energy storage system to ensure power balance and frequency stability at the point of common coupling (PCC) during grid disturbances and fluctuating renewable and load conditions. An LVRT scheme is proposed for the system to ride through grid voltage sags by providing maximum reactive power support, simultaneously reducing voltage unbalance and power oscillations at the PCC, and enhancing the overall power quality of the system. The presented control strategy of DVSI is verified through simulation and experimental studies on the developed hardware prototype.

With the growing integration of renewable energy sources (RES)-fed voltage source inverters (VSIs), ensuring stable and reliable operation of the microgrid system, both in grid-connected and islanded modes, is essential to ensure uninterrupted power supply to loads. This necessitates a robust control strategy capable of handling dynamic transitions and grid disturbances. In this work, a hybrid mode of operation is presented for the dual voltage source inverter (DVSI) topology consisting of a parallel structure of two VSIs that provide active and reactive power to the load independently. The RES-fed VSI operates in grid-forming (GFM) mode, and the second inverter acts as a compensator in grid-following (GFL) mode. The GFM inverter regulates the system voltage and frequency, while the GFL VSI operation is dependent on its connection to the GFM inverter. The system also enables low voltage ridethrough (LVRT) by providing reactive power support to the grid. The DVSI system can be operated under different operating conditions, such as grid-connected, islanded, and weak or faulted grids, ensuring voltage and frequency regulation, load power continuity, and power quality of the system. The developed control strategy for the DVSI system is validated through simulation in MATLAB/Simulink under various disturbances.

Wide bandgap (WBG) semiconductor devices such as gallium nitride (GaN) high electron mobility transistors (HEMTs) have significantly advanced power electronics by enabling higher switching frequencies, compact form factors, greater power density, and improved efficiency. Despite these advantages, accurately modeling losses in GaN-based converters remains a key challenge, especially under varying operating conditions. This paper presents a data-driven loss modeling approach for a GaN HEMT-based buck converter, combining empirical simulation data with theoretical analysis to estimate both fixed and variable losses across a range of switching frequencies and load levels. Curve-fitting techniques are employed to develop analytical loss functions for key parameters, enabling precise prediction of total power loss. The model also facilitates analysis of the trade-offs among switching frequency, efficiency, and thermal performance. Based on this analysis, an optimal switching frequency is identified that minimizes total power loss while maintaining thermal and operational reliability.

This article introduces a novel control strategy for a dc microgrid with integrated photovoltaic (PV) and wind energy sources, combined with a hybrid energy storage system (HESS) comprising a battery and a supercapacitor, feeding constant power loads (CPLs). The supercapacitor's high power density is essential for absorbing transient power components, thus extending the battery's lifespan. However, tightly controlled power electronic converters in this system, which behave as CPLs, potentially lead to instability. To address this, a control method based on super-twisting control (STC) and modified super-twisting observer (MSTO) is proposed for the HESS's bi-directional converters. This approach improves the stability margin, enhances dynamic performance, and tightly regulates the dc bus voltage. In addition, a super-twisting sliding mode controller (STSMC) is employed to track the current reference from the maximum power point tracking (MPPT) algorithm under varying wind speeds in a permanent magnet synchronous generator (PMSG)-based wind system. Theoretical analyses and both simulation and experimental evaluations validate the effectiveness of the proposed control strategy in the PV-wind-battery-supercapacitor-based dc microgrid.

Currently, the world is in the midst of a major energy transition, where renewables and microgrids are positioned to play a pivotal role in restructuring the power system network. In light of this fact, this work details the development of a novel hybrid microgrid topology using the 3-port converter. The topology provides a single-stage power conversion platform between multiple subgrids within the system and allows a seamless transition of the microgrid operation from grid-connected to islanded mode and vice versa. Additionally, this work introduces a power management strategy that optimizes the power flow among various entities in the system while considering different operating conditions. Furthermore, a new offline solar maximum power point tracking (MPPT) scheme is proposed using a predictive approach that minimizes the system's computational load and sensor count. The entire functioning of the proposed hybrid microgrid is verified using MATLAB Simulink, controller hardware-in-the-loop (CHIL) operation performed on the OPAL-RT (OP4510) HIL simulator, and experimentation performed on the developed hardware prototype.

Transformerless inverters with a shared ground connection between source and load are increasingly popular for grid-connected photovoltaic (PV) systems due to their enhanced safety, reduced electromagnetic interference, and elimination of leakage current. This paper proposes a novel switched capacitor based nine-level inverter circuit topology with a four times voltage boosting feature. The inverter shares a common source and load ground, which nullifies the leakage current in the case of PV application. The inverter utilizes eleven switches, two diodes, and three capacitors. The paper discusses the different operating modes, modulation techniques, and a control scheme for the inverter’s closed-loop grid-tied operation. Further, a comparative analysis with recent nine-level common ground type inverter topologies is presented, highlighting the advantages of the proposed inverter. The performance of the proposed inverter is validated through extensive simulation analysis.

Symmetrical and unsymmetrical faults pose significant challenges to the operation of microgrids with integrated renewable energy sources. Unbalanced faults lead to deviations in point of common coupling (PCC) voltage and introduce negative sequence voltage components, driving the system away from its stable operating region. This article proposes a unified voltage ride-through (VRT) scheme for a dual voltage source inverterfed microgrid system to ride through unsymmetrical voltage sags and swells by regulating the PCC voltage while simultaneously minimizing the negative sequence voltage and oscillations in the injected active power with dual sequence current injection. Moreover, VRT is achieved by maintaining the PCC voltages within the nominal range through an appropriate generation of reference voltage. In addition to voltage regulation, frequency deviations due to power imbalances during fault conditions are also damped by adjusting real power supplied to the system. Thereby, consolidated control of positive and negative sequence voltage, oscillating power components, phase voltage deviations, and frequency variations at the PCC is achieved through the proposed VRT scheme, ensuring power quality and reliable operation within rated current limits. The developed control scheme is validated through simulation and experimental studies on the developed hardware prototype for various voltage scenarios.

This article introduces resilient and adaptive power integrator and dispatcher, a multi-input multi-output (MIMO) converter topology designed to operate across various voltage levels. Its key advantage over similar converters lies in providing galvanic isolation among all input–output ports, effectively mitigating risks associated with short circuits and lightning strikes while preventing unintended current flow between multiple ports. Incorporating a multiwinding transformer eliminates the need for power electronic switches on the load side by adjusting the secondary-side turns through uncontrolled rectifiers. This streamlined design, managed by a single controller, significantly reduces system complexity while efficiently allocating available power from renewable energy sources and energy storage systems. A comprehensive seven-port hardware prototype has been developed and tested. The experimental results reveal that the proposed MIMO dc converter can effectively handle the power flow between the ports.

In this paper, an elaborate study on the evaluation of reactive power is presented for non-linear single-phase electrical systems. The study covers prominent power theories proposed over the last century and compares the definitions of reactive power with the standard accepted definition today and the elemental power measured across the reactive elements in the circuit. The paper proposes a power theory called the instantaneous phasor components theory for the most accurate evaluation of reactive power for non-sinusoidal systems. The analysis is carried out using detailed simulation studies for various possible relevant electrical circuits. With the help of experimental studies, the paper validates the compensation abilities of the proposed theory by designing an active compensator for a non-sinusoidal system to achieve a sinusoidal and unity power factor source current.

Increasing demand for effective renewable energy applications has paved the way for many new innovations in bidirectional DC-DC converters. This study introduces a new bidirectional converter, engineered to provide high voltage gain with reduced devices. Apart from its extensive conversion range, the converter offers continuous input and output current, enhancing its compatibility with the DC bus and storage devices. The converter is a dependable option for high-power applications due to its simple circuit layout and fewer components, which allow it to successfully withstand voltage stress across the active switches. In order to make the system even more scalable, the suggested converter takes advantage of a common grounding architecture. Because it doesn’t need a greater duty cycle to achieve efficiency, the converter is well-suited for use with renewable energy sources. Improved scalability and dependability for use with renewable energy sources are goals of the design process. A comprehensive simulation analysis was conducted utilising the MATLAB Simulink environment to validate the proposed converter architecture. The outcomes are compared to the preexisting topologies. The outcomes show that the suggested converter improves voltage gain even with reduced duty cycles.

Transformerless inverters are a popular choice in Photovoltaic (PV) generation systems because of their cost-effectiveness and highly efficient operation. Nonetheless, challenges associated with common-mode voltage have motivated the exploration of alternative topologies, control methodologies, and modulation strategies. In common-ground type inverters, the load and source ground terminals are interconnected, resulting in the bypassing of parasitic capacitances and the complete elimination of leakage current. This paper proposes a novel eleven-level switched-capacitor based inverter topology featuring a common ground connection between the source and load. This topology can achieve a five-fold voltage gain, making it well suited for low-voltage PV systems. The common-ground (CG) feature of this inverter effectively eliminates leakage current and significantly reduces electromagnetic interference (EMI) by bypassing stray capacitance. Consequently, there is no need for an EMI filter. The voltage balancing of the capacitors occurs automatically, without the need for any control scheme, sensors, or closed-loop controllers. A detailed comparison with established CG-based topologies is carried out, emphasizing the parameters of component count, total standing voltage, cost, and volume, which clearly indicate the inverter's improved attributes. The pulse width modulation (PWM) scheme, design guidelines for the switched-capacitor (SC), and loss analysis, including thermal modeling, are discussed in detail. The proposed inverter's feasibility and performance are verified through detailed simulation and experimental studies.

This paper focuses on the control techniques implemented on a PV-wind based standalone DC microgrid with hybrid storage system. An Enhanced Exponential Reaching Law (EERL) based sliding mode control (SMC) is applied for extraction of maximum power in a Permanent Magnet Synchronous Generator (PMSG) based wind energy system. This reaching law based SMC tracks current reference from the optimum torque MPPT algorithm during different wind speeds and load variations and has a good dynamic response. A combination of battery and supercapacitor is used as the hybrid storage system for providing reliable and continuous power to the load. The supercapacitor absorbs the transient components during disturbances and helps in improving the life of battery. A control method based on the Lyapunov function, which can ensure global asymptotic stability is implemented for the bidirectional converter of battery and supercapacitor. The proposed method maintains the DC link voltage constant during solar, wind and load variations. A detailed analysis of the two control laws is presented. The superiority and efficacy of the proposed control strategies are validated on the DC microgrid system during different operating conditions by simulation studies and by developing an experimental test bench.

This paper proposes a novel switched capacitor based five-level inverter with a two-fold voltage gain and common ground (CG) feature. This common ground feature nullifies the leakage current, which makes it suitable for grid-connected photovoltaic (PV) applications. The semiconductor devices in the proposed inverter comprise six switches and one diode, which is low compared to its counterparts. The existing CG-based five-level inverter topologies comprise capacitors rated for twice the source voltage, reducing power density. However, in the proposed inverter, the capacitors are rated for source voltage, which improves the power density and reduces the cost. Capacitor voltages are self-balanced, eliminating the need for a voltage-balancing sensor. Further, a thorough comparison with existing five-level two-fold gain CG-based topologies has been carried out, which shows the merit of the proposed inverter in terms of component count, capacitor voltage rating, total standing voltage, cost factor, and maximum blocking voltage. The modes of operation, modulation scheme, and closed loop grid-connected control scheme are presented. The proposed inverter is simulated using MATLAB Simulink, and the hardware-in-loop test is performed on OPAL-RT 4510 for various steady-state and dynamic conditions, showing the proposed inverter’s efficacy.

The potential of Gallium Nitride (GaN) wide band gap (WBG) power semiconductor devices has been extensively investigated in recent years. The superior figure-of-merits of GaN high electron mobility transistors (HEMT) over contemporary devices like Si MOSFET and Silicon Carbide (SiC) MOSFET gives an edge in power electronics-based industrial applications. However, the privilege of fast switching frequency and low conduction resistance are intimidated by the crosstalk oscillation issues that occur during the switching transients. Therefore, a comprehensive analytical model of the GaN HEMT device based on the Double Pulse Test (DPT) circuit is developed and analyzed thoroughly using the high-frequency equivalent circuit In this paper, the analytical model is developed considering the profound effect of different parasitic elements which includes the gate loop inductance and the stray power loop inductance. Model equations for the current and voltage are derived using the circuit conditions in the Laplace domain, and their nature of oscillation is observed. The simulation of the GaN devices using the DPT circuit is performed in LTSpice and derivation and analysis of model equations of current and voltage for the DPT is done in MATLAB.

The integration of distributed energy resources and decentralized power generation through microgrids has transformed modern power systems. To support this transition, various multiport converter topologies with reduced components have been introduced. Among them, the 3-port converter, previously proposed by the authors, optimizes the integration of different microgrid entities while minimizing the switch count. However, this design increases current flow in certain devices, leading to higher system losses. To address this issue, this paper presents a novel loss minimization algorithm for the 3-port converter. A comprehensive power loss model is developed, accounting for both conduction and switching losses, which is used to develop the objective function. The algorithm employs an optimization function, “fmincon”, that uses a trust region method based on the interior point technique to minimize the objective function. To enhance computational efficiency, a graphical analysis is integrated into the algorithm to predefine solutions for specific scenarios and select optimal input parameters. Next, a port current angle adjustment strategy is introduced to embed the optimization results into the microgrid control structure, ensuring efficient converter operation. The algorithm is validated through Controller Hardware-in-the-Loop (C-HIL) experimentation on a multi-subgrid microgrid setup using the OPAL-RT OP4510 simulator. The algorithm achieves an average reduction of 32 to 46% in losses compared to the worst-case scenario, depending on power flow conditions, demonstrating significant improvements in system efficiency. Additionally, it outperforms other optimization methods in computational speed, confirming its effectiveness in real-time applications.

A Power Management Strategy (PMS) based on a disturbance observer is proposed for a solar-wind-battery-supercapacitor system integrated with the grid. The control scheme for the hybrid energy storage system comprising of battery and supercapacitor is designed using a Second Order Sliding Mode Controller (SOSMC) and a Modified Second Order Sliding Mode Observer (MSOSMO). The power management algorithm determines the mode of operation based on the estimated power value by the MSOSMO. The observer gives a fast estimation of disturbances and thereby the proposed scheme gives better DC bus voltage regulation. The effectiveness of the power management strategy is verified during charging, discharging, and grid-connected modes of operation for different SoCs of the battery and supercapacitor using MATLAB/Simulink.

Multilevel inverters (MLIs) with a common ground (CG) feature have gained significant popularity in transformer-less grid-connected photovoltaic (PV) systems. In this paper, a novel switched capacitor (SC) based common ground type seven-level inverter topology with triple voltage boosting capability has been proposed. The common ground feature of the proposed inverter bypasses the PV stray capacitor, resulting in zero leakage current in the stray capacitor of the PV system. The proposed inverter topology requires two capacitors, rated at the source voltage and twice the source voltage, respectively, reducing overall cost and improving reliability and power density. The pulse width modulation (PWM) scheme balances the voltages across the SCs, which eliminates the need for the sensor for capacitor voltage balancing. The proposed inverter's circuit description, its operating states, PWM scheme, and control scheme for closed-loop grid-connected operation are discussed. Further, a detailed comparison with the CG-type seven-level triple-boost inverter is presented in terms of capacitor voltage rating, component count, cost factor, total standing voltage, total conducting devices per level, and maximum blocking voltage, which demonstrates the improved attribute of the proposed inverter topology. The pro-posed inverter is simulated in MATLAB Simulink environment for various steady state and dynamic conditions, which validate the feasibility and effectiveness of the proposed inverter.

The integration of power electronics in the current power system has presented various challenges, such as unbalance, harmonics, and voltage disturbances. To tackle these issues, this paper introduces a novel UPQC topology with integrated battery storage and solar PV using the 3-port converter. The 3-port converter being part of a reduced switch scheme, achieves the above objectives with only twelve power electronic switching devices. This work describes the operation of the proposed configuration alongwith detailed emphasis on its control aspects. This work also proposes a modified phase angle control algorithm to control the phase angle of the series injected voltage under various grid and load conditions, comparing different UPQC control strategies. The operation of the proposed configuration with the above features and objectives is validated in MATLAB Simulink.