适应于双馈风电场送出线的时域距离纵联方向保护

Longitudinal direction protection of time domain distance applicable to the outgoing line of a double-fed wind farm

针对基于傅里叶算法的距离纵联方向保护应用于双馈风机接入系统会受频偏特性影响这一问题,分析了双馈风机短路电流特性对传统距离方向元件的影响。考虑到双馈风电场的频偏特性,运用了一种时域保护原理,即通过采集双馈风电场送出线两端保护安装处电压、电流时域信息,利用递推最小二乘法辨识出两端保护装置感受到的电阻、电感,将时域距离保护II段作为方向判别元件实现时域距离纵联方向保护。仿真结果表明,该方法不受风电场侧短路电流频偏特性的影响,能准确、快速判断出故障方向,且具有较强的抗过渡电阻能力,提高了双馈风电场送出线纵联方向保护的动作可靠性。

Longitudinal direction protection of distance based on a Fourier algorithm and applied to the access system of a double-fed wind generator is influenced by frequency deviation characteristics.This paper analyzes the influence of short-circuit current characteristics of such a generator on the directional element of conventional distance.Given the frequency deviation characteristics of a double-fed wind farm,it adopts the principle of a time domain protective device.That is,it collects the time domain information of voltage and current at the protective device of each terminal of the outgoing line of a double-fed wind farm,recognizes the resistance and inductance at the protective device of each terminal by means of a recursive least squares method,takes time domain distance protection section II as the element to distinguish direction,so as to realize longitudinal direction protection of time domain distance.The simulation result indicates that this method will not be influenced by frequency deviation characteristics of short-circuit current at the wind power plant,and can identify the fault direction accurately and quickly.It is well able to resist transition resistance and improves the reliability of protection operation of the longitudinal direction of the outgoing line at the double-fed wind farm.