Research On Service Restoration Optimization Method Of Distribution Network With SNOP

With the increasing complexity of distribution network structure,the probability of power failure increases continuously.The power failure in a large scale is a serious threat to the social and economic order,so it is significant to study the service restoration of distribution network to ensure the safety and reliability of power supply.The existing service restoration method based on traditional interconnection switch in distribution network is limited by the switch's response speed,operating life and impact current,which is difficult to realize real-time optimization and uninterrupted power supply in the non-fault area.SNOP(soft normally open point),as a new-type power electronic device,can precisely regulate power flow and realize real-time optimization according to the corresponding control targets.Applying SNOP to resolve the distribution network service restoration problem has obvious advantages in reducing the range and time of power failure and improving the reliability of power supply.This paper considers the application of SNOP based on back-to-back voltage source inverter in distribution network.Firstly,we set up the mathematical model in different coordinate systems and introduce the principle and the control strategy of SNOP under different operating conditions.The simulation model is built on PSCAD/EMTDC to analyze its response characteristics under double closed-loop control.The result shows that SNOP can coordinate the power transmission between the feeders in the power system,suppress the short-circuit current and limit the network fault propagation under the fault condition.Secondly,the protection configuration of the double closed-loop control system in distribution network is studied.Adopt the feeder automation method based on distributed intelligent terminal control,and propose the service restoration process.Finally,the service restoration optimization method of distribution network with SNOP is proposed.Based on the SNOP maximum transfer capability,the optimization model is established with the objective of minimizing the risk of system load loss.The model optimizes output voltage of the port under the VF control mode,solved by Particle Swarm Optimization.Compared with the effect of traditional interconnection switch for service restoration through the case study,the validity of SNOP in improving service restoration ability of distribution network is verified,which can reduce the risk of system load loss and increase the system voltage level.