An Adaptive Coordinated Wide-Area Backup Protection Algorithm for Network Topology Variability

The flexible and variable topology and the high penetration of distributed generations make it difficult to set and coordinate the traditional backup protection based only on local quantities. Therefore, an adaptive coordinated wide-area backup protection algorithm applicable to network topology changes, which is based on a small amount of wide-area information, is proposed. Firstly, an overview is given and the implementation principle is described. Next, the distribution of the amplitude of the positive-sequence fault component voltage is analyzed. It is combined with the inverse-time characteristics equation to achieve online adaptive setting of parameters. A line length influence factor is introduced to ensure the selectivity of the remote backup protection when short lines are included. The operating time of each protection automatically reflects its relative relationship with the fault location to achieve adaptive coordination of local/remote backup protections. Finally, the adaptability of the proposed method is verified when the topology changes, the line length changes and the capacity of distributed generation changes.

I. Introduction

Backup protection is used to cut off failures that are not cut off by primary protection and its operating time is longer to ensure reliability. Since a larger portion of the system is protected, its setting is more dependent on the system operating conditions and more challenging [1]. Unpredictable changes in grid structure and operating conditions may lead to a loss of selectivity in backup protection and further expand the scope of power outages [2], [3]. The high penetration of distributed generations (DGs) changes the magnitude and direction of fault currents, further exacerbating the conflict between selectivity, reliability, rapidity and sensitivity, especially for backup protection [4], [5], [6]. These changes make it increasingly difficult to select protection settings that are suitable for all scenarios. Therefore, existing backup protection schemes based on local information are difficult to adapt to modern power systems with flexible topology changes.