Application Of Reactive Power Compensation Control Strategy In Ultar High Voltage Direct Current Converter Station

Due to the long distance and complex line conditions,the transmission network in the ordinary way is prone to line fault,high loss,wire heating loss and other problems.Using UHVDC to reduce transmission loss and realize stable transmission is an ideal way for remote power transmission.There are some problems in UHVDC transmission,such as long line and complicated situation,so it is necessary to set up a converter station to adjust the line voltage.However,during the operation of the converter Station,the UHV alternating current will produce reactive fluctuations and increase the output current equipment load.For this problem,Station Var Compensator(SVC)is generally used to compensate the converter Station’s reactive fluctuations,so as to ensure the stability of UHV DC power transmission.By analyzing the UHVDC transmission network,this paper finds out the causes of reactive power fluctuations in the converter stations of UHVDC transmission lines.If the reactive power fluctuations are not dealt with,they will have high side effects on the high-voltage current transmission and equipment maintenance.In this paper,PSCAD\EMTDC software is used to construct the corresponding digital analog control model.Through simulation analysis,it can be known that the SVC module can form a negative feedback system in series in the converter station,so as to carry out reactive compensation control for the alternating current mutual inductance generated by the converter station,so as to improve the stability of the transformer system.However,in the actual use of the SVC control module,due to its own characteristics,a large voltage fluctuation will occur in the operation of the weak AC converter bus.On this basis,the cooperative control strategy of STATCOM and reactive capacitor is adopted to ensure the output balance of the combined STATCOM and reactive capacitor.When the dc input current power fluctuates in the converter station,detailed fluctuation information can be obtained by regulating the steady-state voltage and maintaining the voltage stability of the converter bus through capacitor components,so as to provide backup energy for the system in case of failure and realize the control purpose of improving the shock resistance of the system.Finally,through case analysis,the actual application effect of SVC control strategy in UHV DC transmission converter station is clarified,so as to make clear that SVC control module can effectively control the voltage fluctuation of converter station bus,improve unit reactive power grouping capacity,reduce equipment maintenance costs,and improve converter station stability.