基于过渡电阻倾斜角的光伏并网自适应距离保护

Adaptive distance protection based on tilt angle of transition resistance for grid-connected PV station

针对光伏并网距离保护测量阻抗受过渡电阻的影响的问题,提出一种基于过渡电阻倾斜角估计的自适应距离保护。对故障分量的分析结果表明过渡电阻倾斜角θ完全由光伏电站的等效阻抗XN决定,而XN随着光伏电站发电量P的变化而变化。采用最小二乘法估算出P与XN间的关系,从而确定θ。采用相量图获得线路短路阻抗并给出距离保护判据。仿真分析结果显示,所提方法的最大误差为2.4%,低于传统方法的最大误差14%,极大地减小了过渡电阻对光伏并网距离保护测量阻抗的影响。

Since the measured impedance of distance protection for the grid-connected PV（Photo Voltaic）station is affected by the transition resistance,an adaptive distance protection based on the tilt angle of transition resistance is proposed. The results of fault component analysis show the tilt angle of transition resistance,θ,is decided totally by the equivalent impedance of PV power station,XN,which varies with the generating capacity of PV station,P. The relationship between P and XNis evaluated by the least square method for determining θ,with which,the phasor diagram is applied to obtain the line short circuit resistance and set the distance protection criterion. The simulative results show the maximum error of the proposed method is 2.4 %,lower than the maximum error of the traditional method,14 %,which sharply reduces the effect of transition resistance on the measured impedance of distance protection for the grid-connected PV station.