摘要
兆瓦级光伏电站发电单元通常是由2台500 k W并网逆变器和1台1 MVA三相辐向双分裂升压变压器构成,而辐向升压变压器低压绕组间存在较大的分布电容,常发生2台光伏并网逆变器共同运行困难的问题。针对上述问题,对采用三相辐向升压变压器的光伏发电单元进行了等效建模,分析了变压器低压绕组间分布电容对双逆变器共同运行的影响机理。分析结果表明,并联在变压器两低压侧的2台逆变器之间存在漏电流回路,光伏发电单元中延后并网的逆变器直流母线电压升高导致双逆变器共同运行困难。通过仿真验证了机理分析的正确性。最后,提出了2种解决办法,并进行了仿真和实验验证。
The power generation unit of megawatt-level photovoltaic power plant is usually composed of two 500 k W gridconnected inverters and one 1 MVA three-phase radial double-split boost transformer.There is a large distributed capacitance between the low-voltage windings of radial boost transformer.The two grid-connected photovoltaic inverters are often difficult to operate together.Aiming at the issue above,this paper establishes a equivalent model of photovoltaic power generation unit with three-phase radial boost transformer,and analyzes the influence mechanism of distributed capacitance between low-voltage windings of transformers on the joint operation of two inverters.The analysis result shows that there is a leakage current loop between the two inverters connected in parallel on the two low-voltage sides of the transformer,the increased DC bus voltage of the later grid-connected inverter in photovoltaic power generation units makes it difficult for two inverters to operate together.Simulation verifies the correctness of mechanism analysis.Finally,two solutions are proposed and verified by simulation and experiment.
作者
朱大朋
苏建徽
汪海宁
张健
ZHU Dapeng;SU Jianhui;WANG Haining;ZHANG Jian(Research Center for Photovoltaic System Engineering of Ministry of Education(Hefei University of Technology),Hefei 230009,China;School of Electrical Engineering and Automation,Hefei University of Technology,Hefei 230009,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2020年第14期141-147,共7页
Automation of Electric Power Systems
基金
国家重点研发计划资助项目(2018YFB1500802)
中央科研基本业务费资助项目(PA2018GDQT0021)。
关键词
光伏发电单元
并网逆变器
双分裂变压器
分布电容
漏电流
母线电压
photovoltaic power generation unit
grid-connected inverter
double-split transformer
distributed capacitance
leakage current
bus voltage
