Adaptive Stability Control Of Dc Microgrid Bus Voltage Based On Observer Estimation Of System Parameters

Whether the bus voltage of DC microgrid is stable is the main index to measure the power quality of DC microgrid.The nonlinearity and parameter uncertainty are the key factors that affect the stability of bus voltage.In this paper,the DC microgrid is taken as the research object,and to maintain the DC microgrid bus voltage stability as the research purpose,the Backstepping control method based on ESO observer,the Hamiltonian adaptive observer and passive control method are used.The specific research contents are as follows:Aiming at the influence of nonlinearity and parameter changes on the stability of bus voltage in DC microgrid system,a control method combining ESO and Backstepping was proposed.Firstly,the equivalent topological structure and mathematical model of DC microgrid system which is composed of distributed power supply,power electronic device.The equivalent topological structure and mathematical model of the system are established according to the converter with the function of boosting and reducing voltage.The extended state observer(ESO)is used to measure the nonlinear part of the model.The backstepping method is used to compensate the nonlinear part of the system,so as to overcome the adverse effects of nonlinearity and parameter changes on the system and achieve the purpose of controlling the voltage stability of DC bus.The simulation results show that the combination of ESO and backstepping can further improve the stability and robustness of DC micro grid bus voltage control.In order to further accurately observe the change of single parameter in microgrid system,rather than only observe the whole nonlinear part,an adaptive control scheme based on port Controlled Hamiltonian(PCH)system is proposed.Firstly,the model of microgrid system based on buck-boost converter is established and transformed into PCH system model.Then,the controller is designed according to interconnection,damping configuration and energy shaping method.In order to overcome the problem that the system parameters are easy to change,PCH adaptive observer is introduced to observe the system state and parameters at the same time,and is substituted into the designed controller,so as to eliminate the influence of the variable parameters on the micro gridsystem and improve the stability of the DC bus voltage of the micro grid.The simulation results show that the adaptive control method based on PCH system can still realize the stable control of DC bus voltage when the parameters of microgrid system change.The method is simple and effective,and has good stability and strong robustness.