基于统一纵联原理的抗电流互感器饱和保护算法

A Protection Algorithm for Current Transformer Saturation Countermeasures Based on Principles of Unified Pilot Protection

提出一种构建统一纵联保护系统的思想,基于光纤通信系统获取多种模拟量和数字量信息,从而在一套保护系统中实现多种判据,以提高纵联保护系统的性能,并实现诸如重合闸配合、线路参数测算等辅助功能。在此基础上,研究了利用故障方向信息克服差动保护易受电流互感器(TA)特性不一致和饱和等因素影响的方法,分析了TA饱和对电流相量差动元件、正序故障分量方向元件动作特性的影响,表明故障方向元件受TA特性不一致和饱和的影响较小,可以为电流相量差动保护元件进行区内、区外故障判断提供可靠的辅助信息,并据此提出了相应的保护判据。动模实验结果验证了所提出的方案的可行性和有效性。

An idea about structure of unified pilot protection system is proposed.By virtue of optical fiber communication system,it can obtain multi-information such as sample values of analog current,voltage and all kinds of digital information.With these information,it can not only accomplish many criterions in one protection system to enhance the performances of pilot protection system,but also achieve some other auxiliary functions such as re-closure coordination,line parameters calculation and so on.Based on the idea,fault direction information is used to overcome problem that differential protection is easily influenced by current transformer properties difference and current transformer saturation.In addition,a detailed analysis of current transformer saturation effect on performances of current differential component and positive sequence fault direction component is given.The results show that limited influence on fault direction component caused by current transformer saturation,so it can detect fault direction reliably and provide auxiliary information for current differential protection to distinguish internal fault from external one,accordingly,the corresponding protection criterion is put forward.The results of dynamic simulation experiments verify the feasibility and effectiveness of the proposed scheme.