Network Reconfiguration Optimization Of Power Systems With DC Transmission Receiving-End Terminals

With the increasing scale of power grid and the wide application of new technologies,the operation and control of the system are more complex.It can improve the economy and reliability of operation,but it brings new difficulties to the stable operation of power grid.Improper handling of local faults may lead to cascading reactions and eventually lead to blackouts of the whole system.It will cause great losses to social production and people’s lives.So it is very important to study the system recovery after blackout.HVDC transmission has been widely used in China.For the system with DC landing point,the effective utilization of HVDC system during system restoration can accelerate the process of system restoration and enhance the security of system restoration.Firstly,the principle of HVDC transmission and its characteristics in system restoration are introduced.The HVDC start-up mode in system restoration,the requirement of receiving system during HVDC start-up and the selection of control mode are further determined.Then the coordination methods of single-infeed HVDC and multi-infeed HVDC and AC systems in the recovery process are analyzed.The path optimization method used in previous studies severely restricts restoration of LCC-HVDC systems,so this paper studies the system restoration with DC terminal location at receiving-end.Considering the efficiency and security of restoration,the system restoration optimization model considering Parallel Transmission lines is established by taking the ratio of total power generation and grid charging reactive power as the goal.Considering various constraints,the hybrid particle swarm optimization is used to solve the model of power system restoration.The effectiveness of the proposed method is validated by the optimization results on the modified IEEE 39-bus system and a practical power system in Southwest China.A restoration method for system with multi-infeed HVDC is proposed.The two step optimization model of system restoration is set up.Firstly,optimize the objective network aiming at the maximum ratio of the DC power and the reactive power of the objective network.On this basis,the power supply startup order is optimized with the goal of the maximum transmission capacity in the process of system restoration,and optimize the DC power of each step aiming at the maximum total power.Considering the constraints of DC startup and system operation,the hybrid particle swarm optimization,Dijkstra algorithm and linear programming are used to solve the problem.Finally,the effectiveness of the proposed method is validated by the optimization results on the 39-bus system and a practical power system in Southwest China.