Abstract

With the access of a large number of inverter-interfaced distributed generators, the system structure, power flow direction, and operation mode of the distribution network have changed, and traditional single end protection is obviously difficult to meet the requirements. To solve this problem, a power differential protection method is proposed in this paper. Firstly, the output characteristics of distributed generator during LVRT are considered to tap the amplitude and direction characteristics of positive sequence differential power of fault components at both ends of the distribution line. Secondly, the weighted power vector is introduced, and based on its phase difference with the power of the fault components at both ends, the power differential criterion is constructed, which solves the problem that it is difficult to identify the normal unbalance currents and fault currents caused by the DG branch. Finally, it is verified through testing that the protection can reliably identify in-zone and out-of-zone faults, which effectively improves the adaptability of differential protection in distribution networks containing DGs.