Comparative Research Of HVDC Reactive Power Compensation Schemes Based On Three Commutation Technologies

China’s energy and energy load are generally in a reverse distribution,which will enable China to build a UHV HVDC transmission project on a large scale,so as to achieve long-distance and large-capacity optimal configuration of clean energy.Because the conventional HVDC converter station will consume a lot of inductive reactive power at rated operation,the commutation failure is easy to occur when the receiving end is a weak AC system,which greatly limits the application of HVDC transmission.Therefore,it is necessary to improve the topology of the LCC converter and improve the stability of the DC transmission.Based on the above background,this paper applies the CCC and ASCCC converters to the converter station of the weak receiver system according to the parameters of the Jiuhu DC project,and studies the reactive power characteristics of the LCC_HVDC、CCC_HVDC and ASCCC_HVDC systems and the reactive power compensation strategy of the converter station.Comparing the fault characteristics of the system in the event of a short circuit in the AC bus.In this paper,based on the actual parameters of the jiuhu DC project and the control system of the CIGRE standard,the simulation model of the 800 kV DC transmission system is built on the PSCAD software,and the reactive power compensation strategy under the three operating conditions of LCC_HVDC is simulated,and the fault characteristics of the AC bus short circuit are analyzed.The research shows that the voltage stability of the weak AC system is poor,and LCC converter is prone to commutation failure.So,the CCC and ASCCC converters are considered to apply to inverter station.The CCC converter is applied to the weak reception station of the Jiuhu DC project.Analyzing the working principle of the CCC converter and determining the value of the series capacitor,building the simulation model of the CCC_HVDC system,studying the power characteristics and reactive power compensation strategy during normal operation of the system,comparing and analyzing the fault characteristics of the converter station.The results show that when the AC bus occurs the three-phase short-circuit,the CCC inverter station can overcome the fault without commutation failure.When the AC bus occurs the single-phase ground fault,the fault recovery characteristics are poor due to asymmetrical capacitor voltage,and continuous commutation failure occurs.Finally,the new ASCCC converter proposed in this paper is studied.The working principle of ASCCC converter is theoretically analyzed and verified.It shows that ASCCC converter is helpful for commutation.The ASC reactive power is grouped and establishing the system simulation model.Simulation studies the power characteristics and reactive power compensation strategies of the system during normal operation.Through fault simulation,the ASCCC inverter station can overcome the single-phase earth fault of the AC bus,and the three-phase short-circuit fault characteristics are not deteriorated.Based on the actual engineering parameters,this paper applies CCC and ASCCC to the weak receiving end of HVDC system,studing the power characteristics and reactive power compensation strategies of the entire inverter station,comparing and analyzing the fault characteristics of the converter station.The research provides a reference for the engineering application of the converter.