Analysis of Grid-Side Reactance’s Impact on Resonance Characteristic of Multi-Module Parallel Inverter System
Zhang Lei1, Wang Xiaosheng2, Sun Kai2, Zhou Hongwei1
1. TEBA Xi’an Electric Technology Co. Ltd Xi’an 710119 China; 2. State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China
Abstract：The interfacing inverters are usually parallel-connected with modules via LCL filters in a grid-connected new energy generation system. Because of resonance problems of LCL filters, passive and active damping is commonly used to damp the resonance in application. In theoretical analysis, the grid is usually treated as an ideal three-phase voltage source without considering the impacts of grid-side reactance on resonance characteristic. But in industrial applications, however, there is a non-negligible reactance on the grid side because of transformers and wires. Based on the control structure and mathematical modeling, the analysis method of multi-module parallel system is given. Equivalent single model is proposed, and a new variable is defined as grid-side total reactance Lc. Damping effects of several common AD methods with different values of Lc are studied. Moreover, the allowable value range of Lc is given considering system stability. Simulation and experimental results have testified the correctness of theoretical analysis.
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2017, Vol. 32 
