Publication Issue: Volume: 3, Issue: 1, March 2018

Author: Meiqin Mao、Cheng Qian、Yong Ding

Abstract:Virtual synchronous generator (VSG) technology for integration of distributed energy resources attracts increasing attentions for its enabling inverters to simulate the inertia and damping characteristics of synchronous generators and improve the stability of the system. In this paper, a decentralized VSG-based adaptive coordinated control strategy is proposed for islanding microgrids consisting of photovoltaic generators combined with battery energy storages in DC side (PV/BES-VSG). By the proposed method, the droop characteristics of VSGs can be adaptively adjusted according to the DC bus voltage. In this way, the local controllers of PV/BES-VSG units can switch operating modes automatically without the need of a central controller, so that the power sharing among PV/BES-VSG units is allocated according to the maximum output power of PVs and the limit of charging/discharging power of BES instead of merely rated capacity of the inverters. To test the proposed method, an islanding model of microgrid with two PV/BES-VSG units in parallel is built in Matlab/Simulink. The simulation results show that by the proposed control strategy, the coordination control between PV and BES, and between PV/BESVSG units can be effectively realized with maximum use of PV power under the premise of the rational distribution of power.

Publication Issue: Volume: 1, Issue: 1, Dec. 2016

Author: Hirofumi Akagi ; Shin-ichi Kinouchi ; Yuji Miyazaki

Abstract: This paper describes the 750-Vdc, 100-kW, 20-kHz bidirectional isolated dual-active-bridge (DAB) dc-dc converters using four 1.2-kV 400-A SiC-MOSFET dual modules with or without Schottky barrier diodes (SBDs). When no SBD is integrated into each dual module, the conversion efficiency from the dc-input to the dc-output terminals is accurately measured to be 98.0% at the rated-power (100 kW) operation, and the maximum conversion efficiency is as high as 98.8% at 41-kW operation, excluding the gate-drive and control-circuit losses from the total power loss. The bidirectional isolated DAB dc-dc converters are so flexible that series and/or parallel connections of their individual input and output terminals make it easy to expand the voltage and current ratings for various applications such as the so-called “solid-state transformer” or “power electronic transformer.”