Under fault conditions

inverter-based distributed generator (IBDG)

such as photovoltaic power generation system

generates different amount of current

and its value depends on IBDG’s capacity or output power

fault types

fault location and so on. This makes it hard to achieve its setting for a traditional current relaying. In order to solve the problem

adaptive instantaneous trip protection is an effective way. According to the fault characteristics of the distribution network with IBDG

the possible problems of the traditional adaptive current instantaneous protection are analyzed. Considering that the IBDG only exists in the positive-sequence network

an adaptive instantaneous trip protection scheme based on positive-sequence current is proposed to improve its performance by analyzing the relationship between the positive-sequence voltage and positive-sequence current with different fault locations for line-to-line fault and three-phase fault. Finally

the effectiveness of the proposed protection strategy is verified by simulation results of a10 kV distribution network with IBDG. This work is supported by National Basic Research Program of China (973 Program) (No. 2009CB219704)

National Natural Science Foundation of China (No. 51177108) and China Southern Power Grid (No. K-KY2013-116).