距离保护在风电接入系统中的适应性分析

Adaptability Analysis of Distance Protection in Power System Integration with Wind Farms

大规模风电接入交流输电网使得风电系统表现出越来越多异于常规电网的故障特征,传统继电保护应用于风电接入系统时存在适应性问题。距离保护广泛应用于电力系统输电线路保护,研究其对风电系统适应性意义重大。针对距离保护的适应性问题,首先通过各距离保护的基本原理得出其最佳应用条件,然后基于该条件结合风电系统的一般故障特征从理论上对其适应性进行分析,得到距离保护适应性的一般结论。研究结果表明,风电系统的弱馈性和系统阻抗不稳定性使得基于工频变化量的距离保护不适用于风电接入系统,风电系统的高谐波和频偏特性使得工频量距离保护存在相量提取问题,时域距离保护动作性能良好。仿真结果验证了理论分析的正确性。

The large-scale wind power integration into power system shows more and more unique fault features.There exists an adaptability problem when traditional relays are used with wind power.Distance protection is widely used for transmission line protection and its adaptability to the wind power has great significance.To assess the adaptability,the best working condition is firstly obtained by deducing the basic theory of the distance protection.And then,based on the condition and the fault characteristics of wind power system,the protection adaptation is analyzed using theoretical analysis.The research shows that the power frequency variation of impedance protection is not suitable for wind power integration due to poor feedback and instability of wind power system impedance.The power frequency distance protection has phasor extraction problem because of high harmonics and frequency deviation in the wind power system.In the meantime,the time domain distance protection still remains good performance.The above points are verified by simulation results.