Research Of Power System Black-Start Network Partitioning Considering Recovery Sequence

Black-start restoration of a power system after a complete blackout is a very complicated operating process. Reasonable black-start schemes play a major role to the fast restoration of power system after blackout. Partitioning the whole system into several subsystems which are restored in parallel can speed up the restoration process. Black-start network partitioning problem has been researched in this thesis. The problems of system partitioning and the restoration sequence determination of the subsystems are solved in one time by searching the shortest restoring paths. In addition, the load restoration problem is solved by the optimal power flow algorithm. This thesis introduced how to choose the shortest recover paths of units and substations. According to the method, and Floyd algorithm which is used for searching the shortest distance and path between any two nodes in the graph is introduced to choose the recover path for the nodes in power system.Through analyzing and summarizing the start-up characteristics of the units, an optimization approach of network partitioning and the restoration sequence determination for black-start is proposed in the thesis. The optimization target is to restore as many generating units as possible in the shortest time and to balance the restoration times of the subsystems. Based on the three start-up time limits of thermal units, the whole restoration process is divided into three stages. In each stage, the units or substations are ordered according to the corresponding start-up time limit and the shortest restoring paths to the restored area are searched one by one by the Floyd algorithm, then the subsystem in which a unit belongs to can be determined. Through considering the unit's start-up time limits and minimizing the restoration time in the network reconfiguration, the number of the units restarted successfully within the start-up time limits is maximized, so the speed and efficiency of the system restoration can be significantly improved.After completing the reconfiguration of all the skeleton sub-networks, the subsystems are reconnected into the complete skeleton network of the original power system. Then, the loads are restored according to the importance of the loads and the operating constraints of the system.The IEEE 118 bus system is employed as an example to verify the validity of the proposed network partitioning approach, and the IEEE 30 bus system is used to verify the load recovery algorithm.