Design And Research Of Digital Excitation System Based On STM32

Synchronous generator plays an important role in modern power industry and has been widely used in many power generation systems.Excitation control system which provides excitation power and protection for synchronous generator is one of the most important control means to ensure the safe and stable operation of power system.With the development of power electronics technology and embedded technology,the digital excitation control system based on 51 single chip microcomputer,DSP,ARM and other core processors has rapidly become a research hotspot,and the technical performance of excitation controller has been improved.Facing the challenges brought by the development of modern power system,the application of advanced digital excitation control technology to power system can effectively improve the security and stability of power system.In essence,multi-machine excitation system is a nonlinear system with multiple variables and complex variable parameters.In this paper,based on the in-depth study of the third-order model and nonlinear control theory of multi-machine excitation system,a new method of Super-Twisting sliding mode control,variable structure control,adaptive control and inversion control is proposed.A new method to state the amount related to the power deviation State as a whole,gives the operating point under arbitrary load calculation method,for the high order sliding mode theory is applied to the higher order system is not strict parameters feedback affine model structure puts forward the new way of thinking,the control law design involves the state quantity can be measured directly,effectively improve the dynamic control of excitation control system performance.By using MATLAB(Simulink)software,simulation tests are carried out in the simulation model of four engines and two regions,and the effectiveness of the new algorithm is proved.In the face of the problems such as easily induced resonance and voltage fluctuation caused by the grid-connection of large volt power stations,especially the potential interference of large inverters,it is proved that the designed excitation controller can ensure the stability of the power system with photovoltaic disturbance through the simulation model of three generator and two area with 200 MW photovoltaic power station.In order to carry out the physical test experiment,relying on the power system stability control experiment platform,through the design of analog signal acquisition,driving circuit,power supply circuit and other circuits,the excitation hardware control system based on STM32F103ZET6 ARM is developed.Based on the modular design concept and in the Keil u Vision5 programming environment,the system initialization,analog signal acquisition,PWM driver,excitation limitation module and other subprograms are compiled.Combined with the Super-Twisting sliding mode adaptive distributed excitation control strategy,the realization method of excitation control system software is given.Based on the experimental platform of power generation and supply equipment,the designed excitation controller is physically tested under two working conditions of sudden load increase and sudden load decrease.Simulation and physical test results show that compared with traditional PID+PSS control method,a new control method can reduce the system voltage stability time,reduces the amount of overshoot state variables,effectively guarantee the power system containing large-scale photovoltaic power station stability,improve power system line fault resistance and the ability of load fluctuation has certain positive meaning.The designed digital excitation controller has the advantages of high control precision,intuitive display and easy operation,which provides a new technical means for improving the stability of power system.