Optimal Configuration And Control Of Distributed Condensers In Renewable Energy Gathering Area

Severe transient overvoltage will occur after the commutation failure of the DC external transmission system in the renewable energy collection area,which will cause the high-voltage disconnection of the renewable energy station at the end of the power grid at the sending end.Distributed synchronous condensers have great reactive power regulation characteristics,and the distributed configuration of distributed synchronous condensers on the renewable energy side is an effective solution to suppress the transient overvoltage of renewable energy stations.However,However,there is a relative lack of research on overvoltage suppression by distributed synchronous condensers.Therefore,it is of great theoretical and engineering significance to study the influence mechanism of DC commutation failure on the transient overvoltage of renewable energy sources.Meanwhile,in order to reducing the transient overvoltage of renewable energy stations by using the synchronous condenser,it’s also significant to study the configuration scheme and operation control strategyCommutation failure is a frequent DC fault in the renewable energy collection area using HVDC.Firstly,based on the operating principles and control strategies of DC transmission systems,we analyze the mechanism of transient voltage generation in rectifier station after commutation failure.Then,we analyze the reactive power response characteristic of diverse reactive source in the renewable energy collection area in the transient period,and the transmission mechanism of the transient voltage from the rectifier station of the sending end power grid to the renewable energy station is studied.This is followed by the analysis of the impact of wind farm access on the system transient overvoltage characteristics in combination with wind farm control methods and high/low voltage ride-through strategies,and the cause of the most serious transient overvoltage on the renewable energy side is deduced.Secondly,by studying the reactive power response characteristic of the synchronous condenser,SVC and STATCOM,the paper simulates and analyzes the advantages of the synchronous condenser in suppressing the transient overvoltage of renewable energy sources area,and the suppression effect of the centralized or decentralized access mode of the synchronous condenser on the transient voltage is studied.On this basis,an optimization scheme is proposed for the decentralized configuration of synchronous condensers on the renewable energy station side.The scheme uses the improved trajectory sensitivity index to evaluate the effect of the system voltage level increase,which considers the characteristic of dynamic reactive power compensation after the synchronous condenser is connected.And improved trajectory sensitivity index is used to determine the candidate nodes for installing the synchronous condenser.We adopt multiple renewable energy stations short-circuit ratio that consider the characteristic of the renewable energy collection area power grid,measure the voltage intensity of the renewable energy station,and study the influence of the short-circuit ratio after the synchronous condenser access.Propose optimization determines the installation capacity of the synchronous condenser through this index,so as to achieve the optimization goal of the optimal economy.By building a renewable energy collection area delivery system in PSD-BPA,the effectiveness of the optimized configuration scheme designed is verified by simulation.Finally,in order to improve the reactive power response performance of the synchronous condenser during operation,optimization research is carried out on the control strategy of the synchronous condenser both in steady state and transient operation stages.We study the influence of the steady-state reactive power output of the synchronous condenser on the transient reactive power response performance,and verify the validity by simulation to provide guidance for the reactive power control mode of the synchronous condenser in steady-state operation.Based on the traditional reactive power-voltage double closed-loop excitation control model of the synchronous condenser,paper proposes an evaluation index of the dynamic reactive power characteristic of the synchronous condenser considering the control parameters of the excitation system.The sensitivity analysis of the excitation control parameters is carried out on the index,and the optimization direction of the control parameters is obtained.Paper introduces fuzzy control theory,proposes a Mamdani fuzzy PID synchronous condenser excitation control system.Proposed design scheme uses reactive power frequency domain sensitivity analysis results to formulate fuzzy control rules,and uses PSCAD to simulate the effect of transient voltage suppression on the renewable energy side under different faults.The comparison of traditional double closed-loop control and fuzzy PID control effects verifies the fact,which is that the proposed optimized excitation control system can effectively improve transient reactive power response performance and reduce voltage fluctuation during fault recovery.