基于分布式电源电流变化率的主动配电网单相断线保护方法

分布式电源的应用，改变了配电网断线故障的特征，加剧了断线故障的威胁。但是目前不仅缺乏含分布式电源(DG)的配电网断线故障保护方法，甚至电网断线故障下DG的输出特性也不清晰。基于主动配电网的可观测性，提出了一种根据DG电流变化率识别配电网断线故障的新思想。首先，分析了配电网单相断线故障下DG的输出特性，并建立了DG的等值模型。然后，建立了含DG的配电网单相断线故障等效电路，推导了故障前后DG输出电流的表达式。随后，分析了故障前后DG输出电流的变化特征，建立了基于DG电流变化率的辐射状配电网单相断线故障保护判据。仿真表明，所提单相断线故障保护方法能够迅速识别断线故障并准确定位。

A protection method of a single-phase break fault for an active distribution network based on current change rates of distributed generation

The application of Distributed Generations (DGs) has changed the characteristics of break fault and increased the threats in a distribution network. However, there is a lack of protection methods for break fault in distribution networks with DGs, and even the characteristics of DGs under break fault are unclear. Based on the observability of an active distribution network, this paper proposes a new idea to identify the break fault in a distribution network based on the current variation rate of DGs. First, the output characteristics of DGs under a single-phase break fault in a distribution network are analyzed, and the equivalent models of DGs are established. Then, the equivalent circuit of a distribution network with DG under a single-phase break fault is established. The expressions of the current contributed by the DG before and after the single-phase break fault are derived. Subsequently, the current characteristics of DG before and after the break fault are analyzed, and a protection criterion for a single-phase break fault in a radial distribution network is established according to the current variation of the DG. The simulation shows that the proposed method can quickly detect and locate the break fault. This work is supported by National Natural Science Foundation of China (No. 51877018).