考虑不可测负荷分支的有源配电网单相断线故障保护方法

Single-phase Disconnection Fault Protection Method of Active Distribution Network Considering Unmeasurable Load Branch

有源配电网断线故障造成过电压、人身伤亡及电机损毁等事故时有发生,针对这一问题,首先分析了有源配电网断线故障后各节点负序阻抗以及断口两侧零序电压差。借鉴电流差动保护的思想,定义了负序差动阻抗,基于区内外故障时负序差动阻抗的特征差异,提出了一种基于负序差动阻抗的保护方法。该方法利用负序差动阻抗幅值作为动作量,利用其相位构造具有自适应性的制动阈值。其次,针对重载保护失效的情况,提出了将零序电压幅值差作为辅助判据。最后,分析了不可测负荷分支对上述保护判据的影响,并提出了通过比较负序电流幅值进行故障定位的方法。仿真结果表明,所述方法可以可靠定位,具有不受中性点接地方式、过渡电阻、负荷以及分布式电源影响的特点。

The active distribution network disconnection fault causes accidents such as overvoltage,personal injury and death,and motor damage.To solve this problem,we first analyzed the negative sequence impedance of each node after the active distribution network disconnection fault and the zero sequence voltage difference on both sides of the fracture.With the idea of current differential protection for reference,the negative sequence differential impedance was defined.Based on the characteristic difference of the negative sequence differential impedance when the fault occurs inside and outside the area,a protection method based on the negative sequence differential impedance was proposed.This method uses the amplitude of the negative sequence differential impedance as the amount of action,and uses its phase to construct an adaptive braking threshold.Secondly,in view of the failure of the overload protection,we proposed the zero sequence voltage amplitude difference as an auxiliary criterion.Finally,we analyzed the influence of the unmeasurable load branch on the above protection criterion,and proposed a method for fault location by comparing the magnitude of the negative sequence current.The simulation results show that the method can reliably locate fault and has the characteristics of not being affected by the neutral grounding method,transition resistance,load,and distributed power sources.