To enhance the gain of conventional boost converters in applications such as fuel cells and photovoltaic systems, cascade boost converters are normally applied. In this study, a new cascade boost converter topology with reduced conduction losses is proposed. This converter shows reduced root‐mean‐square currents of the circuit elements and reduced conduction losses. The proposed converter is analysed and compared with the conventional circuit topology. The proposed converter has all the advantages of cascade boost converter with the advantage of reduced conduction losses. Finally, simulation and experimental results of a 200 W laboratory prototype are presented.

In this paper, a decentralized control strategy for inverter‐based distributed generation (DG) is proposed to enhance the accuracy of power sharing under unbalanced load conditions in low‐voltage microgrids. The proposed method includes two important saliences: (1) accurate unbalanced current injection from DGs, and (2) reduction of circulating real and reactive powers in an islanded microgrid. The features are complied with the proposed droop strategy utilized in the control system of each phase of DG converters. Based on the proposed triple‐droop control strategy, the real power sharing in an AC low‐voltage microgrid is significantly improved via P–V control strategy and the reactive power sharing accuracy is enhanced via Q–f control strategy. By this method, the amplitude of the output voltage of each phase of the converters is determined based on the amount of load connected to that phase. In addition, the efficiency of the microgrid is increased due to the circulating current reduction between DGs. A virtual impedance concept is also utilized to improve the accuracy of the proposed power sharing method. The feasibility and effectiveness of the proposed strategy are validated using MATLAB/SIMULINK software for International Council for Large Electric Systems (CIGRE) low‐voltage distribution network benchmark.

A single-phase Three-Level Split-Inductor Neutral Point Clamped Inverter-Improved (3L-SI-NPCI ² ) for transformerless photovoltaic (PV) application is proposed in this article. The proposed inverter utilizes two split inductors, which eliminate the shoot-through issue. Therefore, it is more reliable than conventional converters. Not needing dead time, achieving a high efficiency with lower current THD and low leakage current are other advantages of the proposed inverter. The operation principle, dynamic performance, output filter design and impacts of asymmetric filter inductors on leakage current are illustrated in the 3L-SI-NPCI ² . The proposed topology is compared to seven existing transformerless topologies by simulation studies and results. Finally, an experimental prototype has been developed to show the benefits of the proposed inverter.

In this paper, a multi-functional control strategy is proposed for an accurate sharing of oscillatory and dc components of load currents among distributed generation (DG) units in a dc microgrid. The proposed controller is composed of a voltage control loop and a multi-loop current control unit. The voltage control loop is used to regulate the microgrid voltage as well as to share the dc component of load current through the conventional droop scheme. The current controller includes two main units to simultaneously (1) manage the oscillatory current sharing, (2) improve the stability of control unit, (3) diminish the voltage ripples, and (4) protect the DG units against overloads. In this paper, the idea of virtual conductance is introduced to modify the output impedance of converters for oscillatory current sharing among DG units. To restrict the instantaneous current of DG units under overload conditions, a maximum current limiter unit is introduced to the control system. The compensation signals of these units are eventually applied to the inner current control loop. This scheme guarantees the microgrid voltage to be maintained within the tolerable range under a variety of oscillatory conditions. The stability of the system is studied using small signal analysis. The proposed control scheme is examined in two different microgrid configurations of radial and ring structures. The effectiveness of the proposed method is evaluated through simulation studies.

This paper presented an accurate analysis of the instability in DFIG-based wind farms due to the use of series compensation and provided maximum power extraction from these farms using the high compensation without the unstable sub-synchronous oscillation occurrence. For this purpose, using modal analysis, it is first shown that the main cause of this instability is low wind speed in the high compensation. This issue causes the series compensated DFIG-based wind farms is unstable due to a sub-synchronous mode. In order to prevent the unstable sub-synchronous oscillation occurrence, a supplementary controller called SSRIPC and DFIG controllers are used. Also, for good dynamic response and proper use of the SSRIPC, an objective function considered based on three factors of minimum damping ratio, overshoot, and settling time of the oscillations. By accurate optimization of the proposed controller using root-locus and PSO algorithm, it is prevented the instability caused by sub-synchronous resonance and sub-synchronous control interaction that are classes of the sub-synchronous oscillations. IEEE SSR first benchmark model and MATLAB/Simulink software are used to validate the performance of the proposed method.