基于两电平电压源型换流器的直流微网交直流侧接地方式

Grounding Modes at AC and DC Side of DC Microgrid with Two-Level Voltage Source Converters

随着分布式能源、直流负荷、变频负荷及电压敏感负荷的快速发展,直流微网将在未来电网中得到广泛应用。现阶段直流微网的接地设计尚无统一规范,国内各示范工程采用的接地方式也各有所异。本文针对基于两电平电压源型换流器的直流微网,从交直流侧谐波的角度分析了各种接地方式的利弊,推荐交流侧采用换流器LCL滤波器的滤波电容中性点接地方式,直流侧采用直流电容中性点接地方式。实际工程中接地方式的选取需考虑多个方面的因素,因此本文结论不可作为直流微网接地设计的评判标准,但可为设计人员提供参考。

With the rapid development of distributed energy,DC load,variable frequency load and voltage sensitive load,DC microgrid will be widely used in future power grid.At present,there is no unified standard for grounding design of DC microgrid,and the grounding methods used in various demonstration projects in China are also different.In this paper,the advantages and disadvantages of various grounding methods for the DC microgrid are analyzed based on two-level voltage source converter(VSC)from the perspective of AC and DC side harmonics.It is recommended to adopt the filter capacitor neutral point grounding method of converter LCL filter on the AC side and DC capacitance neutral point grounding method on the DC side.The selection of grounding method in practical engineering needs to consider many factors,so the conclusion of this paper can not be used as the evaluation standard of DC microgrid grounding design,but they can provide reference for designers.