Research And Implementation Of Reliable Control Method On Capacitor Compensation Synchronous Switching System

Reactive power compensation of low-voltage distribution system is a necessary mean to improve voltage stability,to ensure the power supply quality and grid security.Dispersion compensation at the user side,which not only can achieve the local balance of reactive power load,but configure compensation capacity flexibly,has hardly impact on grid,and obvious effect on energy saving and loss reduction,so it is widely used by high energy consumption enterprises.However,recently,there are many problems in the low voltage reactive power compensation capacitor switching device,such as being poor in switching time precision,high in cost and low in reliability.Meanwhile,the information indication and communication ability are not good enough in operation management.In view of the above problems,the work on research and design has been completed as the following.Firstly,based on the analysis of low voltage capacitor switching device application status,development trend as well as advantages and disadvantages of various devices,combined with the user needs,this paper designed a synchronous switching system of low voltage capacitor based on magnetic latching relay.Secondly,through the mechanism modeling and experimental simulation,the influence of overvoltage and inrush current on the compensation system is studied under different initial phases.Further,this paper analyzed the advantages and disadvantages of the several typical schemes respectively,aiming at existent puzzle in crossing zero detection circuit,designed the AC signal crossing zero detection circuit by constant current diode.Thirdly,the factors affecting the operation time of magnetic latching relay have been studied by means of experimental statistics method,and then the adaptive prediction model of relay operating time has been established.This paper analyzed the time sequence of capacitor switching control,and designed the coding number of state decreasing method to schedule system switching process.Meanwhile,the paper also studied on the puzzle of zero interference signal filtering,phase sequence identification and phase tracking in complex power supply environment.Fourthly,aiming at actual user needs,this paper completed the design of hardware and software system,achieved a synchronous system based on crossing zero switching by the main control board and the auxiliary board,and proposed the method used for automatic serial coding number and type recognition so as to solve the puzzle in device management and communication.Finally,by waveform measurement,the paper verified the correctness of the synchronous switching system.The running results of the prototype also show that the designed system can run stably and reliably,and it can better meet the user's needs.