Distributed Power Service Restoration Method For Smart Distribution Grid

Fault is one of the important factors that affect the power distribution reliability.After the fault occurs,the non-fault outage area should be restored as soon as possible.In the past,the centralized method of power service restoration is mainly adopted.Master station by means of distribution terminals obtains network topology information,electric quantity information of each node and switching information,etc.Then,based on that information,the optimization algorithm of power service restoration is implemented to obtain the restoration scheme.In the end,the switch operation command is sent to the distribution terminal.In the practical application,centralized method has many problems,such as information collection difficulties,large amount of calculation,the implementation of the effect to be improved.In view of the problems existing in the traditional centralized power service restoration method a distributed power service restoration method for smart distribution grid is proposed.The method is based on the smart terminal unit(STU)arranged at each measuring point of the distribution grid,and through the information interaction and cooperation between the STU,the power service restoration task is completed.Combined with characteristics of distributed system and requirements of service restoration,distributed management of network topology information,network topology equivalence method,searching method of network topology and the simplified calculation method of the constraint conditions are analyzed and studied.This paper describes the structure and function of distributed power service restoration system with STU as the core,and simplifies the equivalence of network topology by graph theory.The principle of reciprocating search is put forward,and the determination of the theoretical maximum restoration range and the determination of the scope of the actual restoration are completed.A simplified method for solving the constrained condition is proposed.The method is based on stepwise Thevenin equivalent.The power and voltage constraining are carried out in the search process,without the need for centralized power flow calculation.In order to improve the power distribution reliability,the supporting role of distributed generation and microgrid is considered.The paper also considers and analyzes the STU failure and the special situation of the search process.This method is suitable for the structure of the distribution network and flexible operation characteristics,and can automatically identify the network topology,with good fastness and adaptability.Using peer to peer communication method to exchange information,reduces communication pressure and improves the communication speed.Each STU has the ability to independently guide the power supply restoration,and can be used for parallel processing in the case that the fault causes a plurality of non-fault outage areas.Finally,two case study is given to show the effectiveness and correctness of the proposed method.