A Photovoltaic Generation System Based on Wide Voltage-Gain DC-DC Converter and Differential Power Processors for DC Microgrids

Chinese Journal of Electrical Engineering ›› 2017, Vol. 3 ›› Issue (1): 84-95.

A Photovoltaic Generation System Based on Wide Voltage-Gain DC-DC Converter and Differential Power Processors for DC Microgrids

Zhaoxin Qiu, Kai Sun^*

State Key Laboratory of Power System, Tsinghua University, Beijing, 100084, China

Published:2019-11-01
Contact: E-mail: sun-kai@mail.tsinghua.edu.cn.
About author:Zhaoxin Qiu received the Bachelor’s Degree in 2014 in Electrical Engineering from Tsinghua University, and is studing as a master student in State Key Lab of Control and Simulation of Power Systems and Generation Equipments in Tsinghua University. His research interest is power electronic technology in generation systems with renewable energy sources. Kai Sun received the B. E., M. E., and Ph. D. degrees in electrical engineering from Tsinghua University, Beijing, China, in 2000, 2002, and 2006, respectively. He joined the faculty of Electrical Engineering, Tsinghua University, in 2006, where he is currently an Associate Professor. From Sep 2009 to Aug 2010, he was a Visiting Scholar at Department of Energy Technology, Aalborg University, Aalborg, Denmark. From Jan to Aug 2017, he was a Visiting Professor at Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Canada. His current research interests include power electronics for renewable generation systems, microgrids, and active distribution networks. Dr. Sun is a member of IEEE Power Electronics Society Sustainable Energy Systems Technical Committee, a member of IEEE Power Electronics Society Power and Control Technology Committee, and a member of IEEE Industrial Electronics Society Renewable Energy Systems Technical Committee, and a member of IEEE IAS Industrial Drive Committee Awards Sub-committee. He is an Associate Editor for the Journal of Power Electronics. He was a recipient of the Delta Young Scholar Award in 2013.
Supported by:
Supported by National Key Research and Development Program (2016YFB0900205) and National Natural Science Foundation of China (51577102).

Abstract

Abstract: In this paper, a photovoltaic(PV) generation system based on front-stage differential power processors(DPP) and BACK-stage centralized wide voltage-gain converter is proposed. The resonant switched capacitor(ReSC) converter, which features high power density and high efficiency, is employed as the differential power processor and aims at processing the differential power among series-connected PV modules, avoiding the great power loss caused by power mismatch of PV modules. The ReSC converter in PV system can operate in equalization mode or MPPT mode and both modes are researched. The BACK-stage DC-DC converter is implemented as the dual- phase-shift controlled full-bridge converter(DPS-FBC). It has high conversion efficiency and wide voltage gain, suitable for PV generation applications. The current source control for grid-connected mode and the voltage source control for islanding mode are developed for DPS-FBC. Therefore, for the whole system with front and BACK stage converters, the dual-mode control strategy is proposed. When the system is connected to the grid, DPS-FBC operates as the current source for global MPPT for PV modules while ReSC converters operate in maximum power point tracking(MPPT) mode for local MPPT. When the system operates in an island, DPS-FBC works as the voltage source for constant output voltage control and ReSC converters work in equalization mode. The mode switch is based on the voltage of output DC bus. Simulations and experiments verify the feasibility of the proposed PV generation system and the effectiveness of the proposed control algorithm

Key words: Photovoltaic system, resonant switched capacitor, dual phase-shift control, soft switching

Zhaoxin Qiu, Kai Sun. A Photovoltaic Generation System Based on Wide Voltage-Gain DC-DC Converter and Differential Power Processors for DC Microgrids[J]. Chinese Journal of Electrical Engineering, 2017, 3(1): 84-95.

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