Research On Optimization Of Structural Parameters Design Of New-type High Capacity Condenser

With the advantages of fast response speed and large capacity,large capacity new condenser is more and more used in UHVDC converter station.The dynamic performance of the condenser includes rapidity and dynamic reactive power output.Its complex structure and various operating conditions can meet the requirements of the converter station.However,the rapidity has some shortcomings compared with the static var compensator(SVC),static synchronous compensator(STATCOM)and other power electronic reactive power compensation equipment,the dynamic reactive power output also needs to be improved.The dynamic performance of the condenser is mainly related to reactance,time constant and other parameters.The adjustment of the parameters will bring about changes in the structure of the body,and the reactive power,temperature rise,loss,electromagnetic force and other properties will also change accordingly.Therefore,it is necessary to comprehensively consider the performance of the key parameters of the condenser.At present,most literatures focus on the research of condenser control strategy,but ignore the optimization of ontology structure.In this thesis,taking a 300Mvar new condenser in an electric power plant as an example,through the ANSYS Workbench software simulation platform,the research is carried out from the steady and transient reactance and the time constant of open and short circuit,and the main body structure parameters that affect the dynamic performance are analyzed and optimized.At the same time,the analysis of power,loss,temperature rise and other factors is supplemented to ensure that the condenser can meet the requirements of power grid,the dynamic performance is improved.Firstly,the steady-state and transient reactance of the condenser and the time constant of open and short circuit are studied by formula method.It is found that the dynamic reactive power output is mainly related to transient reactance X’d and sub transient reactance X"d,and the rapidity is related to armature reactance Xad,d-axis short-circuit transient time constant T’d and d-axis open circuit transient time constant T’d0.According to the flux linkage method of motor design,it is concluded that the main body structure affecting Xd and T’d0 is the length of iron core and the size of air gap.The main structure which has great influence on the transient and sub transient reactance is the winding pitch,the height width ratio of slot and slot wedge.Secondly,according to the structural design parameters of the condenser,the geometric and finite element models of the condenser are built in ANSYS,and the external circuit model is established.The air gap flux density,reactive power,back EMF and other parameters are analyzed under rated and no-load operation,and the accuracy of the model is verified comprehensively.The relationships between the core length,air gap size,slot type and coil pitch and reactive power,short-circuit ratio,dynamic reactance,time constant and other parameters are obtained.The dynamic performance of the condenser can be improved under the condition that the reactive power basically meets the demand.The loss of each part of the condenser is analyzed,and the core loss is accurately calculated by the finite element method.The thermal conductivity of the condenser material,the heat dissipation coefficient of the structure and the heat generation rate are equivalent,and the three-dimensional model of the condenser is established.The temperature rise of each part under rated operation is simulated and analyzed by using the transient thermal solver.The results show that the temperature distribution is reasonable.At the same time,the temperature change after the structure change is obtained,which provides the auxiliary support of temperature field for improving the dynamic performance of the condenser.Finally,the causes of noise and vibration of the condenser are analyzed.It is found that the radial electromagnetic force Fr is the main source of electromagnetic noise and vibration.The Fr of the condenser is calculated and analyzed by software.The change of Fr with the change of groove type was studied.At the same time,the Fourier analysis of the induced electromotive force is carried out to clarify the relationship between pitch and harmonic,which provides support for the study of dynamic performance in terms of noise,vibration and harmonic.