Analysis And Strategy Against Influence Of PV Power Station On Relay Protection Of Power Distribution Network

By the end of 2015,China's photovoltaic power generation installed capacity of 43.18 GW,beyond Germany to become the world's largest country of photovoltaic power generation installed capacity.As a supplement of large power grid,distributed generators are developing rapidly for its high efficiency and environmental protection.PV power station like springing across the country to flourish together.However,after PV power station is connected to the distribution network,the traditional single-source radial-network will become to be a double terminal or multi-terminal power network,and the direction of the trend will change,too.This will bring a series of problems for the relay protection,such as misoperation and as function and will affect the automatic reclosing.The effect will be more obvious,especially when large-scale distributed generators are connected.Studying the distribution network relay with the interaction of PV power station and proposing a new protection scheme have an important significance.Firstly,this paper introduces the application of PV power station which are used more widely.Based on the fact that the majority of PV power station is connected to distribution network by the power electronic devices,this paper analyses the working principle and failure response of inverter interfaced PV power station as a key and determines the model and control mode of inverter interfaced distributed generators to provide a theoretical foundation for the following work.Secondly,starting from the type,capacity and location of PV power station,this paper analyzes the effect on protection and automatic reclosing of distribution network with the interaction of PV power station.By using the electromagnetic transient simulation software MATLAB/simulink,this paper builds the typical model of 10 kV distribution network to tests the theoretical analysis further.Finally,based on the wide area protection,this paper puts forward to a new protection principle which can be divided into two steps: first,the branch where fault occurs is identified to locate the fault direction in a relatively small range with the practical criterion for the fault direction of the nodes with multi-branch;second,in view of fault direction,by building a communication unit between the first line and the second one,the fault will be located accurately.In this way can we reduce the processing of useless node information in the network effectively.Finally,by simulating of the new protection principle with the MATLAB/simulink,the results show that the new protection principle can be used to determine the fault range,and has a good application prospect.