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Research On Inverter Port And PCC Unbalanced Voltage Control Under Microgrid In Island Mode

Posted on:2021-02-04Degree:MasterType:Thesis
Country:ChinaCandidate:J L LiuFull Text:PDF
GTID:2392330614459473Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
When the microgrid is operating in island mode,the system voltages are surpoted by coordinate operation of inverter units in the network,and thus the inverter control performance will directly affect the power supply quality of the system.Considering the existence of a large number of single-phase loads in the micro-grid,the system load is actually characterized as unbalanced,which is easy to cause the unbalanced system voltage,which affects the quality of the system power supply and the system stability.Therefore,this paper studies on the voltage unbalance control of microgrid system based on unbalance voltage compensation control of the inverter port and the unbalance voltage coordination compensation control between the inverter port and the PCC.The main research contents are as follows:In terms of the topology of inverter unbalanced voltage compensation,the characteristics of three phase three wire microgrid inverter,isolated microgrid inverter,three phase four bridge arm microgrid inverter and three phase split capacitor microgrid inverter are analyzed and compared in detail.The mathematical model of inverter is established and the voltage unbalance compensation of microgrid inverter with different topology is comparely simulated.In the aspect of voltage imbalance control of microgrid inverter,the existing voltage imbalance control technology of microgrid inverter is analyzed and discussed.From the point of view of control flexibility,an unbalance voltage compensation control method with controllable voltage unbalance degree at the port of microgrid inverter is proposed.Aiming at the difficulty of PI parameter setting of microgrid inverter under different operating conditions,a PI parameter setting method based on particle swarm optimization(PSO)is proposed,and the detailed pso optimization process and parameter optimization method are given.The simulation model of microgrid system under unbalanced load is set up,and the power distribution,port voltage unbalance degree control and particle swarm PI parameter optimization of microgrid inverter are simulated and verified.In terms of the coordinated control of voltage unbalance degree of the microgrid inverter port and PCC voltage unbalance degree,this paper analyzes and discusses the mechanism of unbalanced load of the microgrid under unbalanced voltage in detail,and introduces the principle of negative sequence voltage coordination compensation.Aiming at the control of voltage unbalance at both the port voltage and the common connection point(PCC)of the microgrid,a negative sequence voltage coordinated compensation control strategy based on particle swarm optimization(PSO)is proposed.The compensation algorithm takes the inverter port voltage and PCC voltage imbalance degree as the constraint condition to establish the objective function,and considers the circulation problem between the inverters,so as to reduce the circulation between the inverters while realizing the control of the inverter port and PCC voltage imbalance.The system simulation model is established for simulation verification,and the system semiphysical model is built for experimental verification.
Keywords/Search Tags:microgrid, unbalance, parameter, PSO, voltage compensation
PDF Full Text Request
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