计及逆变型分布式电源控制特性的配电网故障分析方法

随着分布式电源(DG)的大量接入,DG的故障穿越行为对配电网的故障特性影响很大。而传统的等值模型均未计及DG的控制策略,从而造成含DG的配电网故障分析存在不可忽略的局限性。为此,文中在系统分析DG控制策略和动作行为的基础上,建立了计及控制策略的逆变器并网方式下DG压控电流源等值模型,更加真实地体现出DG故障电流的输出特性。在此基础上,通过建立故障前后电网支路电流和节点电压关系方程,推导出故障穿越时DG输出电流与公共连接点电压的求解方程组,从而建立故障精确分析方法。最后,基于DIgSILENT建立含DG的10kV配电网仿真模型,验证了所述方法的正确性和有效性。

Fault Characteristics Analysis of Distribution Networks Considering Control Scheme of Inverter Interfaced Distributed Generation

With the integration of large quantities of distributed generators(DGs) to the grid,the ride-through behavior of DGs has significant impact on the fault characteristics of a distribution network.However,control strategy was not considered in the traditional equivalent model and this caused significant limitations on fault analysis of distribution network with DGs.By analyzing the control scheme and behavior of DGs,this paper presents a voltage-control current source equivalent model for DGs with an inverter interface taking its control scheme into account.This model reflects the output characteristics of DGs even better.Based on this,the equations between the node voltage and feeder current before and after fault are derived.Then,the equations describing the relationship between fault current of DG and point of common coupling(PCC) are built;and the precise method for fault analysis is thus obtained.A 10 kV distribution network case is built in DIgSILENT to validate the proposed method.