Research On Voltage Stability Control Of Self-excited Asynchronous Motor Based On Magnetic Energy Regenerative Switch

With the gradual depletion of global energy and the growing problem of environmental pollution,clean and efficient renewable energy has attracted people’s attention.Asynchronous motor is an indispensable component in renewable energy generation,which is widely used in small-scale hydropower generation.It has the advantages of high reliability,simple control,low investment cost and easy parallel operation.However,in independent power generation of the asynchronous motor,due to the load and xcitation capacitance problem,voltage regulation and load carrying capacity are poor.it is difficult to operate normally,resulting in fluctuations in the output voltage of the asynchronous motor.Aiming at the voltage fluctuation of asynchronous motor,this paper proposes a research that voltage regulation control of SVC-MERS structure with variable capacitance characteristics for asynchronous motor independent power generation system.Firstly,according to the structure and working principle of asynchronous motor power generation system,the steady-state and transient models of asynchronous motor are established,and the influence of excitation capacitance and load changes on the output voltage of asynchronous motor is analyzed.It can be seen from the results that when the load changes,the output voltage of asynchronous motor will fluctuate,and the magnitude of excitation capacitance affects the voltage building process.When the excitation capacitance is too large,the voltage will rise sharply,while when the excitation capacitance is too small,the normal voltage can not be built.Secondly,according to the analysis of capacitance characteristics,three kinds of magnetic energy regeneration switches with different structures are introduced,and the working state changes of full-bridge SVC-MERS are analyzed theoretically,and its mathematical model is deduced by Fourier transformation,the equivalent capacitive reactance modelγand V_C-min is established.According to the transformation of simulation parameters,the results can be obtained.Whenγincreases,the reactive output and the maximum capacitance voltage will increase,while THD will increase first and then decrease;and when increased,reactive power will reduce.In this paper,the parameter coordination control technology is used to change the characteristics of capacitance by controlling the inverse variable parametersγand V_C-min,and the dynamic voltage stabilization control of self-excited asynchronous motor is realized.Finally,the voltage and frequency fluctuation caused by the power fluctuation of the induction motor independent power generation system is deeply studied,and the voltage stabilization control system of the asynchronous motor composed of SVC-MERS is built.When SVC-MERS is connected to the induction motor,the voltage stability control system of the induction motor is built.The built-up voltage response of induction motor is accelerated,and when the load changes,the induction motor can adjust voltage and load-carrying capacity very well.Then,according to the simulation model,the experiment platform is built.Through the power regulator,the double closed loop control and parameter optimization can be effectively combined to achieve bus power balance,stabilize the voltage and frequency,and improve the power quality.It is of great significance for the popularization and application of asynchronous motor.