考虑并网运行微电网故障方向识别的逆变型分布式电源故障控制

Fault Control of Inverter Interfaced Distributed Generator Considering Fault Direction Identification of the Grid-Connected Microgrid

微电网具有双向故障电流,其保护的一个关键问题是如何准确判别故障方向。对微电网正序故障附加网络的分析表明,逆变型分布式电源(IIDG)正序故障分量阻抗角所在象限决定了正序故障分量方向元件在并网运行微电网中的适用性。然而,IIDG功率输出策略的多样性和故障后IIDG并网点电压变化的不确定性导致IIDG正序故障分量阻抗角所在象限无法确定。对此,该文提出一种多阶段的IIDG故障控制方法,通过改变IIDG在特定时间窗口内的故障响应特性将其正序故障分量阻抗角控制为给定值,从而在微电网中构造出不依赖于IIDG功率输出策略的正序故障分量特征。基于Simulink的仿真结果验证了采用所提出IIDG故障控制方法时微电网故障方向识别的准确性。

The microgrid fault current is bidirectional,and a key issue of its protection is how to determine the fault direction.The analysis of positive-sequence additional network of microgrid shows that the applicability of the positive-sequence fault component(PFSC)based directional element in girdconnected microgrid is decided by the quadrant of the PSFC impedance angle of inverter interfaced distributed generator(IIDG).However,due to the diversity of IIDG power output strategy and the uncertainty of voltage variation at the IIDG coupling point,the quadrant of PSFC impedance angle of IIDG cannot be determined.In this regard,this paper proposed a multi-stage IIDG fault control method.By manipulating the fault response characteristic of IIDG in a specific time window,the PSFC impedance angle was controlled to a given value,so as to construct a PSFC feature independent of IIDG power output strategy in microgrid.The Simulink simulation results verified the accuracy of the microgrid fault direction identification by adopting the proposed IIDG fault control method.