电动汽车充电系统集群接入配电网谐波谐振机理分析

Analysis of harmonic resonance mechanism of electric vehicle charging system cluster connected to distribution network

具有V2G功能的双向电动汽车充电系统(electric vehicle charging system,EVCS)可与电网或微电网交换能量,并提供灵活调度、电压支撑等辅助功能,是未来电动汽车充电基础设施的发展方向。然而,双向EVCS大量接入配电网,可能对电能质量造成负面影响。多个EVCS之间以及EVCS与配电线路之间极易产生谐波谐振,导致电能质量劣化。因此,有效分析EVCS接入引起的配电网谐波谐振对于提升系统可靠性具有重要意义。为此,构建了EVCS及配电网常用元件的多输入多输出阻抗模型。基于该模型,提出包含系统d、q轴不对称动态的广义模态分析法。所提方法为精确分析包含多个EVCS的配电网谐波谐振提供了通用步骤,为新型配电网谐波谐振抑制奠定了理论基础。

The bidirectional electric vehicle charging system(electric vehicle charging system,EVCS)with V2G function can exchange energy with the power grid or microgrid,and provide auxiliary functions such as flexible scheduling and voltage support.It is the development direction of future electric vehicle charging infrastructure.However,the large-scale access of bidirectional EVCS to the distribution network may have a negative impact on the power quality.Harmonic resonance is very easy to occur between multiple EVCS and between EVCS and distribution lines,resulting in deterioration of power quality.Therefore,effective analysis of the harmonic resonance of the distribution network caused by EVCS access is of great significance to improving system reliability.To this end,this paper constructs a multi-input and multi-output impedance model of EVCS and common components of the distribution network.Based on this model,a generalized modal analysis method including the asymmetric dynamics of the system d and q axes is proposed.The proposed method provides a general procedure for accurately analyzing the harmonic resonance of the distribution network containing multiple EVCS,and lays a theoretical foundation for the suppression of harmonic resonance in the new distribution network.