A Medium-Voltage DC Collector Grid for PV Plants Using Multi-string MPPT Converter

Abstract

Medium-voltage DC (MVDC) collector grid has been a promising solution to improve energy yield of large-scale PV farms. To enable higher energy yield, multi-string maximum power point tracking (MPPT) DC-DC converter is desirable. This paper presents an non-isolated MPPT DC-DC converter for MVDC PV collector grid. Different from traditional MPPT converters, the proposed converter can operate in both buck and boost modes, which allows strings with large voltage difference coupled to a middle DC voltage. The power processing analysis indicates that the proposed converter features partial power processing in both buck and boost operations. Simulation simulation results are presented to confirm the high efficiency of the proposed converter. Mission profile based evaluation has been conducted to demonstrate that with the proposed buck-boost converter, more energy can be captured than using the conventional boost-only converter.

Authors 4

1. Zhongyi Quan

   University of Alberta

   Affiliation as printed

   Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Canada

2. Jingxin Hu Aachen Institute for Power Generation and Storage Systems (PGS) E.ON Energy Research Center

   RWTH Aachen University

   Affiliation as printed

   Institute for Power Generation and Storage Systems E.ON Energy Research Center, RWTH Aachen University, Aachen, Germany

3. Yunwei Li

   University of Alberta

   Affiliation as printed

   Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Canada

4. Rik W. De Doncker Aachen Institute for Power Generation and Storage Systems (PGS) E.ON Energy Research Center

   RWTH Aachen University

   Affiliation as printed

   Institute for Power Generation and Storage Systems E.ON Energy Research Center, RWTH Aachen University, Aachen, Germany