Research Of The Protection Of The Distribution Network With Photovoltaic Power

As the photovoltaic power scale, the expansion capacity in the power generation and the improvement in the proportion, making the distribution network from the traditional radial single supply network into dual-side or multiterminal network, thus changing the size of fault current, duration and its direction, the results may cause that the circuit breaker protection malfunction and refuse to move and lose the selectivity; also make the fuse lead to loss of selectivity. Photovoltaic 's own fault will affect the operation and protection of the system. In addition, when anti-islanding time of photovoltaic power generation system protection can not be coordinated with automatic reclosing and so on, it will lead to asynchronous closing. Therefore, it is necessary to make an in-depth study for the impact of photovoltaic power on the distribution network protection and solutions, coordinate the relationship between the distribution network protection and photovoltaic power self-protection under the system fault conditions. bring into full play the positive role of photovoltaic power, to minimize its negative impact on the stability and security, make the power system more efficient, reliable operation.This paper analyzes the impact of photovoltaic power on distribution network protection, automatic reclosing and distribution automation. On the modified IEEE34 node distribution network model, using PSCAD simulation shows the impact and contribution of the location and capacity of photovoltaic power on fault currents, as well as the impact of protection devices, the use of heuristics obtained photovoltaic capacity of different access points. Putting forward one new protection approach, that is, without changing the situation of orginal protection, adding impedance current limiter in the photovoltaic power side, effectively addressing the coordination between the photovoltaic power and distribution network protection.For related problems with the interconnection protection of photovoltaic power, analyzing the impact of the interconnection transformer connections on interconnection protection, the adopted proposal should be using the Yn/d transformers. Describing several aspects which will lead to failure of the inverter of fault detection, analyzing of the photovoltaic interconnection protection device on the impact of contact line protection, introducing the islanding detection principles and methods of interconnection protection, and for the photovoltaic power system existing the islanding, a new method of islanding detection is proposed, which improves the principle of power directional relay by adding a hold circuit module initiated by the trip signal module in the original module, thus it can reliably detect the island operation of photovoltaic power.