说明：   距离保护R-L模型算法 使用图基滤波器 控制阻抗轨迹显示范围 在阻抗平面画出阻抗圆特性、整定阻抗直线特性和短路阻抗轨迹
( RL model algorithm for distance protection using map-based filter control the impedance locus in the impedance plane display range characteristic impedance circle draw, setting characteristics and short-circuit impedance line impedance locus)