Study On Direct Axis Reactance Parameters Of Highcapacity Condenser For UHVDC Converter Station

UHVDC converter station high-capacity condenser is a kind of rotating motor equipment specially used for dynamic reactive power compensation of power system.State Grid Corporation has proposed to consider high-capacity condenser as dynamic reactive power compensation equipment for UHVDC converter station.The first batch of 300 MVA large-scale condenser has been successfully developed,and is currently in the stage of trial operation and application promotion.Direct axis reactances are important parameter for highcapacity condenser.It is of great significance to optimize the design of the electromagnetic structure parameters of high-capacity condenser,to measure the parameters accurately,and to successfully apply and popularize it in the power system to study the influencing factors of the important performance parameters of the condenser,and to explore the variation law of the direct axis reactances under different electromagnetic structures and different saturated operation conditions.In this paper,the first batch of 300 Mvar high-capacity condenser in China National Grid are taken as research objects.The effects of electromagnetic structure and magnetic circuit saturation on the direct axis reactances are calculated,analyzed and verified by experiments from the aspects of finite element calculation and real machine experiment.It lays a foundation for the next step of the optimization of electromagnetic structure parameters of high-capacity condenser,the manufacture of model machine,the research of transient parameter test method and parameter identification.Firstly,the parameter requirement of high-capacity condenser used in converter station is analyzed.The typical operating conditions of high-capacity condenser used in converter station are discussed,and the requirements of reactive power output capacity and corresponding key performance parameters of the converter station are analyzed.Compared with the typical parameters of traditional turbogenerator and common condenser,it shows that the reactive power output capability index of high-capacity condenser is higher,and the value of direct axis reactances parameter are much lower.Secondly,the finite element parameterized physical model of 300 Mvar high-capacity condenser is established.The finite element transient reactance calculation based on superconducting circuit and three-phase sudden short circuit is carried out respectively.In this part,the theoretical derivation and parameter calculation are carried out,and the calculated values of transient reactance and super-transient reactance under the designed electromagnetic parameters are obtained.Furthermore,the influence of the size of electromagnetic structure on the reactance of the direct axis is calculated and analyzed by finite element method,and the curves of the reactance of the direct axis with different structural parameters are drawn.According to the calculation results,an parameter adjustment example of the condenser is analyzed.The conclusion can provide reference for the optimization design of the electromagnetic structure of the condenser.Moreover,the influence of core saturation on the reactance of the direct axis in transient process is calculated and analyzed by using the frozen permeance method,and the curves of the reactance of the direct axis under different stator and rotor currents are drawn.The reactance parameters of 300 Mvar high-capacity condenser are tested,and the accuracy of the finite element method for calculating the direct axis reactance is verified.Finally,this paper summarizes the content of this paper and looks forward to the next work plan.