Research On Loop Closing Control Method Based On PMU Technology For Distribution Network

With the increasing requirements of customers for power quality and power supply reliability,it has become a general trend that through loop closing control to achieve line maintenance and load transfer without power outage in distribution network.Due to a large number of intermittent,random distributed generation,flexible load and electric vehicle accessed to distribution network,the difficulty of safe and stable control has greatly increased.Besides,the problem of loop closing control is becoming much more complex.To ensure success rate of loop closing control,the method based on PMU technology for distribution network is studied in this dissertation.Firstly,this dissertation introduces measurement principles and algorithms of PMU technology,basic structure of PMU devices,and discusses application prospects of PMU technology in the loop closing control of distribution network.Moreover,based on the assumption that PMUs are used to obtain structural parameters and operating data of the target network to be looped,and considering the effect of transformer magnetizing inrush current,the impact process of loop control on distribution network,including steady process and transient process,is analized in detail,which is verified by typical 10 kV feeder and 110 kV bus loop closing control systems simulated by PSCAD / EMTDC software.Secondly,the influence of distributed generation on judgment conditions of loop closing control is analyzed based on generalizing judgment conditions in traditional distribution network.Besides,how the capacity and position of distributed generations act on loop closing current is verified by PSCAD/EMTDC.Furthermore,based on the application of PMU data and the regulation of distributed generation,judgment conditions of loop closing control in traditional distribution network is simplified,and an optimization method,throughing flexible adjusting the loop network of distributed generation and obtaining the operation state of distribution network in real time,is proposed to reduce the amount of unnecessary calculations or simulations as much as possible.Lastly,a scheme of loop closing control system is further designed based on PMU technology.This system adopts the control strategy which combines PMU synchronous real-time data and successful experience,simplification and creation of judgment conditions of loop closing control.Meanwhile,in the process of solving the problem of loop closing control,PMU high-density synchronous real-time data in distribution network,and the regulation of distributed generation,flexible load and electric vehicle are made full use of to create favorable loop closing control conditions.It is of great reference value to achieve the maximum function of PMU and distributed generation.