Research On Comprehensive Control Method Of Power Quality In Distribution Network Based On ASVG

In view of the increasingly complicated and various power quality problems of the low voltage distribution network.research on general and comprehensive control equipment will become a developing trend in the field of power quality.In this paper,the control technology of three common power quality problems(the imbalance of three-phase current,harmonic pollution and reactive power insufficiency)in low voltage distribution network were compared and analyzed,it's common characteristics were summarized.Therefore,an advanced static var generator(ASVG)that comprehensively controls the above power quality problems has been developed.The device not only deals with three kinds of power quality problems selectively,but also realizes the goal of comprehensive correction.It could show great practicability in the field of power quality.Firstly,the common topology of ASVG were comparatived and analysised,Then,the topology of three level ASVG with neutral point clamped was selected in this paper.Based on the above topology,the work principle and working mode of the main circuit are analyzed in this paper.At the same time,the mathematical model of ASVG is established.On the aspect of current detection algorithm,the zero sequence component of current was separated based on the traditional dqO detection algorithm,then the remaining current component was transformed by Clarke model.At the same time,an phase-locked technology of dual dq coordinate transformation was introduced.After the application of phase-locked technology,an current component detection algorithm based on dual dq coordinate transformation was proposed.On the aspect of control strategy,according to mathematical model of two level adaptive hysteresis control method,the three level adaptive hysteresis current control method of ASVG was proposed.At the same time,using the traditional PI double loop control method to maintain DC voltage stability and neutral point potential balance of ASVG in this paper.In order to solve the problem that the output current of ASVG contains high order harmonics,the performance of three kinds of filters was compared and analyzed in this paper.Based on the above analysis,the LCL filter was selected as a port of ASVG to connect the power grid.Finally,combined with the parameters of application background,the parameters of LCL filter and main circuit were designed.Finally,a prototype of ASVG has been designed and developed based on design parameters of the foregoing in this paper.At the same time,the architecture of main circuit and the design of hardware and software of the prototype are described.After that,the function of ASVG and the improved detection algorithm and the control strategy were verified in the simulation environment of MATLAB/SIMULINK and the laboratory environment selectively.Based on the prototype of ASVG,Wi-Fi monitoring system of mobile phone and remote monitoring system based on GPRS have been designed and developed,that could provide convenience for the users to monitor the operation of ASVG.