基于阻抗特性的IIDG孤岛保护与故障穿越协调运行方法

针对逆变型分布式电源(IIDG)的孤岛保护和故障穿越两种功能存在的运行冲突问题,提出一种基于公共连接点(PCC)阻抗特性的IIDG孤岛保护和故障穿越协调运行方法。基于PCC等效阻抗的传递函数解析模型,分析并网和孤岛运行状态下的阻抗特性。根据孤岛和电压暂态扰动情况下PCC阻抗的变化特征实现了同一逆变器中孤岛和电压暂态扰动现象的同步检测,从而正确执行孤岛保护与故障穿越两种功能。算例表明,所提方法可以有效辨识孤岛和电压暂态扰动现象,协调IIDG的孤岛保护和故障穿越两种功能,对已有的故障穿越和动态无功支撑方法具有较好的兼容性,有利于IIDG主动参与电网调节,更好地适应在配电网中的高渗透并网。

Impedance Characteristic Based Coordinated Operation Method for Islanding Protection and Fault Ride-through of Inverter Interfaced Distributed Generator

For the operation conflict problems existing between islanding protection(IP)and fault ride-through(FRT)function of inverter interfaced distributed generator(IIDG), an impedance characteristic based coordinated operation method for IP and FRT of IIDG is proposed. Based on the transfer function analytical model of equivalent impedance at point of common connection(PCC), the impedance characteristics under conditions of grid-connected and islanding operation are analyzed. The simultaneous detection of islanding and transient voltage disturbance in the same inverter is achieved according to the variable features of PCC harmonic impedance, thus the IP and FRT functions are performed correctly. Example analysis shows that the proposed method is able to effectively identify islanding and transient voltage disturbance, while coordinating the IP and FRT functions. It has better compatibility for available FRT and dynamic reactive power support methods. Thus, it is beneficial for IIDG to actively participate in grid regulation and better adapt to high penetration integration in distributed networks.