中文摘要：

光伏发电和高压输电网并网时,其特有的短路特性造成接地距离保护分支系数不确定,进而导致保护拒动或误动。针对某实际光伏电站结构,采用序分量原理建立光伏电站等效阻抗XG2与分支系数Kf之间的关系模型;利用光伏逆变器直流侧电压、电流和交流侧电压、电流计算了等效阻抗XG2,并结合实测数据绘制出光伏电站发电量P和XG2之间的关系曲线,采用曲线拟合法求解二者的关系模型。根据XG2、Kf的关系和P、XG2的关系推导出P和Kf的关系模型,并采用自适应原理建立了接地距离保护Ⅱ段阻抗整定值判据。以某地区电网为例进行算例验证,结果表明了P和Kf的关系模型的正确性,以及建立的判据的实用性。

英文摘要：

When PV（Photo Voltaic） generation is connected to high-voltage transmission grid,its short circuit characteristics make the branch coefficient of grounding distance protection uncertain,causing the improper operation of protection. According to the structure of an actual PV station,a model of relationship between its equivalent impedance XG2 and branch coefficient Kfis established based on the sequence component theory,the voltages and currents at AC and DC sides of PV inverter are applied to calculate XG2,the curve of relationship between PV station capacity P and XG2 is drawn according to its measured data,and the curve fitting method is adopted to solve the P-XG2 relationship model. The P-Kfrelationship model is deduced according to the XG2-Kfrelationship model and the P-XG2 relationship model,and the criterion of grounding distance zone-Ⅱ is established based on the self-adaptation principle. With a regional power grid as example,the results of case study show the correctness of the deduced P-Kfrelationship model and the practicability of the established criterion.