Study On The Characteristic Analysis And Optimization Method Of The Orthogonal Magnetic Flux Coupled High Temperature Superconductivity Controllable Reactor

Controllable reactor(CR)is an important reactive power compensation device,which has been widely uesed in the power system.The traditional CRs have many problems in terms of harmonic content,field winding induced voltage,and winding losses.With the improvement of power quality requirements,new CRs with flexible control,low harmonic content,continuous smooth regulation,and low lossses become the future direction.The superconductor has zero resistance and high flow density characteristics at low temperatures.The application of the superconductor technology in the excitation winding of the CR can provide efficient and stable excitation for the reactor,achieve deep saturation of the core,and reduce the volume of the reactor,reduce winding losses,and then improve the use efficiency of CR.A novel type of orthogonal magnetic flux coupled high temperature superconductivity controllable reactor(HTS-CR)has been proposed.The reactance characteristic of the HTS-CR and the operating status of the excitation windings have been analyzed,the multi-physics coupling and the comprehensive optimization design method of the HTS-CR have been studied,which have been researched and verified through a laboratory scale prototype development and a conceptual design of 110kV/30 Mvar prototype.The highlights of this paper mainly reflect in the following aspects:1)Based on the extensive investigation and analysis of the problems of traditional controllable reactors,this paper proposes an orthogonal magnetic flux coupled HTS-CR.In order to analyze the principle of regulation,the analytic model is bulitd and the relaxation iteration method is used to achieve fast solution.The reactance output characteristics are tested by theoretical analysis and experiment.The results show that this type of HTS-CR is demonstrated to have characteristics of low harmonic content,small induced voltage of excitation winding,and stable reactance value.2)In view of the structural characteristics of the orthogonal core,the influence of the anisotropic magnetization and hysteresis effect on the reactance output and dynamic response characteristics of the HTS-CR has been modeled and studied.Considering the complex electromagnetic environment of the HTS excitation windings,three simplified calculation method including A formulation + H formulation method,equivalent magnetic perme-ability transfer method and A formulation coupled with H formulation method are proposed in order to deal with the problem of nonlinearity caused by saturation of the iron core.A multi-section separation method is proposed for 3D asymmetric structures.This method can evaluate the losses characteristic of superconducting area in magnets with complex structures,which has great significance to the design of magnet parameters and control strategy.3)Aiming at the multi-physics issues involved in performance analysis,this paper proposes an operational status analysis method based on dynamic electromagnetic-thermal field-circuit coupling and a response status analysis method based on dynamic inductance matrix.These two methods have solved the problem of neglecting the running state of the magnets and the inaccurate external characteristics in the system application of the HTS magnet.Aiming at the problems of inaccuracy in parameter optimization and impossibility in calculation based on traditional analytical algorithms,an analytical method of response characteristics in the frequency domain of nonlinear ferromagnetic materials is proposed,and based on frequency domain analysis and estimation of AC/DC mixed condition,a model used for parameter optimization is built,which achieve fast optimization of multiple working conditions under the premise of guaranteeing precision.Based on the frequency domain optimization and the multi-field coupling analysis method,a comprehensive optimization design method that follows the three steps of optimization for structure parameters,design for HTS winding and check for operating characteristics is established.4)In order to verify the application of this type of reactor in the power network,the electromagnetic design of a 110kV/30 Mvar HTS-CR prototype have been completed,and the output characteristic of the reactance are analyzed.The losses analysis,cryogenic design and support structure design of the dynamic process are completed,and the non-linear system components are packaged based on the dynamic inductance matrix.The effect of reactive power compensation and the response characteristic of the magnet are verified in the system simulation.