多环电网方向保护整定计算中形成有向简单回路的新方法

在高压或超高压电网的距离保护和零序保护的整定计算过程中，首先要确定全网的最小断点集(MBPS)，然后在断点集的保护安装处打开断点，使得全网变为辐射网络。其中，多环复杂电网中有向简单回路的确定是求解最小断点集的关键，也是其必要步骤之一。为了最大限度地减少多环复杂电网中有向简单回路的计算复杂性，该文提出了一种保护依赖度和主／后备保护依赖集的新概念：将所有有向简单回路的形成过程归结为环网中所有保护依赖度大小的比较和保护依赖集的不完全深度优先搜寻过程。通过比较保护依赖度的大小来确定每次方向回路搜索的起始点，并通过对保护依赖集的深度优先搜索来确定所有有向简单回路。该方法能统一处理环网中的‘T’形接线、辐射线路等保护的配合问题。算例表明该方法简单有效，显著地降低了计算的复杂性，可方便地应用于高压或超高压电网的距离保护和零序保护的整定计算。

A NEW ALGORITHM TO DETERMINE DIRECTIONAL SIMPLE LOOPS DURING SETTING AND CALCULATING OF DIRECTIONAL RELAYS PROTECTION IN A MULTI-LOOP ELECTRIC POWER NETWORK

Determination of minimum break point set (MBPS) is the first step during setting and calculation of zone protection and zero sequence protection in a high voltage or super-high voltage electric networks. After all the MBPS are found out, opening all the relays installed on the MBPS and let the multi-loops a radiate network is the second step. However, to determine directional simple loops in multi-loop complex power network is the key step during calculation minimum break point set (MBPS). In order to reduce the complexity of calculation them, new concepts named protection dependency dimension (PDD) and primary/back-up protection dependency set (PDS) are put forward for the first time in this paper. Comparing protection dependency dimensions and the depth-first-search of protection dependency set could form all the directional simple loops. The beginning point of searching directional loops every time could be determined by comparing the protection dependency dimension. And found out all the simple loops by depth-first-search method. Protection coordination of T-connected lines and radiate network can be deal with in the same time. The example has shown that the algorithm is very simple, effective, and reduced the complexity of problem greatly. It could be used in set and calculation of zone protection and zero sequence protection expediently in HV or EHV power network.