Research On The Influence Of Distributed Power Supply On The Protection Of Distribution Network

With the development of the economy and the progress of the society,power users have put forward higher requirements for basic electricity.Traditional power generation methods can not only meet the demand of the general public,but also bring more pollution problems to the surrounding environment.The emergence of solar photovoltaic power generation technology has solved this problem well.Distributed power supply can integrate photovoltaic power generation technology into the current distribution network well to ensure the stability and security of the entire system.In the process of distributed power supply access,there will be faults in distribution network.These failures will affect the flexibility of distributed power supply and cause short-circuit phenomenon.Therefore,it is very important to study the influence of distributed power supply on relay protection.In this paper,the distributed power supply technology and the standard of grid connection are analyzed based on previous experience and domestic and foreign literature theory.The influence of distributed power supply on the current characteristics of different fault locations and relay protection of distribution network is studied emphatically.The improvement strategy of distributed power supply network relay protection mainly starts from different access points,linkage protection schemes and access distribution schemes.Finally,PSCAD / EMTDC simulation software is used to systematically analyze the feasibility of the above improvement schemes.Through the influence of distributed power supply on the relay protection of distribution network,it is found that if the fault point appears near the downstream of the power supply,the short-circuit current and the non-fault line current will cause the current passing through the power supply to increase dramatically.After formula calculation,it can be seen that the intervention of distributed power supply will make the relay protection system less sensitive,and it will also produce protection rejection,and even lead to an error action induced accident in the system.If the power input is at the end of the distribution network,it is necessary to access the balance device in the middle and end of the distribution network to ensure the balance of the distribution network circuit.At the same time,negative feedback adjustment device is added to the distribution network to cope with the sudden situation.The power distribution network input in the middle section should be connected to the selective device at the port of the distribution network,and the balance device of the distribution circuit at the end is used to achieve the control and stability of the circuit;The power supply input at the end of the distribution network must add a regulator to the port and middle section of the circuit to ensure the overall stability of the circuit.Finally,the mathematical simulation model was established by PSCAD / EMTDC.