基于自适应阻抗继电器的风电T接线路纵联保护方案

Pilot protection scheme for power transmission line with T-type wind power connection based on adaptive impedance relay

风电的T型接入改变了系统拓扑和故障特性,导致继电保护整定与配合困难,传统距离保护应用于风电T接线路时存在适应问题。基于风电T接线路拓扑,分析了双保护方向对保护范围的影响,推导了测量阻抗表达式并提取了主要影响参数,指出风电的T型接入影响距离保护的动作性能;鉴于此,提出了基于自适应阻抗继电器的风电T接线路纵联保护方案。该方案实现了保护方向的唯一化,且保护动作区域能够根据过渡电阻、三端电源电势幅值比、相位差和风电电源等效序阻抗的变化进行自适应调整,提高了保护的可靠性和灵敏性。同时给出了自适应整定阻抗的具体计算方法,一定程度上降低了保护对通信系统的要求。仿真结果验证了所提保护方案的正确性和有效性。

The T-type connection of wind power to the grid has changed the topology and fault characteristic of electric power system, bringing difficulties for relay protection setting and configuration. So there exists an adaptability problem when traditional distance relay is applied to power transmission line with T-type wind power connection. Based on the topology of power transmission line with T-type wind power connection, the influence of double protection direction on the protection range is analyzed. The measuring impedance expression is derived, and the main in- fluencing parameters are extracted. It is pointed out that the T-type connection of wind power will affect the operating performance of distance protection, aiming at which, a pilot protection scheme for power transmission line with T-type wind power connection based on adaptive impedance relay is proposed. It has only one protection direction and its operation zone can be adaptively adjusted according to the variation of transition resistance, the amplitude ratio and phase difference of the three terminal electromotive forces and equivalent sequence impedance of wind power, which improves the reliability and sensitivity of the protection. Meanwhile, a calculation method of the impedance adaptive setting is given,which reduces the requirement of protection for communication system to a certain extent. Simulative results verify the correctness and validity of the proposed protection scheme.