Distributed Fault Self-healing Scheme And System Development For Active Distribution Network

The wide integration of distributed generation(DG)makes traditional distribution network become active distribution network(ADN),at the same time,it brings new problems to the self-healing control of distribution network.Firstly,fault currents in distribution network are multidirectional,so that the traditional fault location method is no longer applicable.Secondly,in the process of fault recovery,the existence and influence of DG should be considered.Therefore,it is of practical significance to study the self-healing scheme of ADN.In order to make the proposed scheme apply to practical application,the corresponding distribution network terminal unit and self-healing system should also be developed.The main work of this thesis is as follows:(1)A distributed fault self-healing scheme based on peer-to-peer communication between smart terminal units(STU)is proposed.The scheme uses current differential protection and fault current amplitude comparison as the fault location principle,which is adaptive to active distribution network with different DG types and penetration rates.(2)A scheme for identifying and storing distribution network topology information under distributed control mode is proposed.This scheme has low requirement for data calculation and storage of STU.It only needs to configure basic static network topology information for STU,and can automatically complete the topology identification and update information during the operation process to adapt to the operation mode change.(3)A distributed fault recovery scheme for ADN is proposed.Under the condition of satisfying the power constraints,the scheme designs reasonable fault recovery rules,which can restore as many important loads as possible.The existence of DG is also be considered,different processing methods are designed according to whether it can run in islanding mode for a long time or not.(4)The STU is developed and tested by Real-Time Digital Simulator(RTDS).Based on existing hardware and software platforms,the STU which can realize the self-healing scheme proposed in this paper is developed.A simulation model of ADN is built in RTDS system,and the closed-loop test between simulation system and STUs is realized.The test results show that the self-healing scheme is fast and reliable,and has greater advantages compare with existing scheme.The STU can operate correctly and has stable performance.