Design Of Power System Stabilizer And Droop Control Of Weak Grid Based On Fractional-order PID Controller

To increase the stability of the power system,the proportion-integral-derivative controller(PID controller)has attracted extensive attention in the electric power industry due to its simple operation mechanism and convenient installation.However,with the continuous development of technology,the problem of insufficient flexibility of the controller has also been exposed.Fractional-order PID controller has strong control capability and control the output of the system in the real number field.It can accelerate convergence speed,improve optimization accuracy and increase global convergence.In this paper,Levy mutation Imperial Competition Algorithm(LMICA)is proposed to adjust control parameters.Aiming at the stability problem of interconnected weak AC system,fractional-order PID controller is proposed to improve Power System Stabilizer(PSS)and droop controller respectively,so as to further explore the frequent occurrence of low frequency oscillation in interconnected power system and grid-connected inverter system.The details are as follows:Firstly,the control principle of fractional-order PID controller and its necessity in improving the system are introduced.Meanwhile,the advantages of the LMICA are analyzed.Secondly,to strengthen the ability of restraining low-frequency oscillation,improve the setting range and control ability of traditional PSS designs,this dissertation designs a PSS system by introducing the fractional-order PID controller,which has the advantages of flexible control ability and good tracking performance.Then the LMICA is adopted to optimize the parameters of the improved PSS,and corresponding simulation is carried out by a single machine infinite bus system.The simulation results show that the proposed model can fully suppress the low frequency oscillation of power system,and the controlled object can be flexibly control with very good control effectiveness and robustness.Finally,an improved droop control model based on fractional order PID controller is proposed.The LMICA is used to adjust the control parameters of the presented model.It is verified that the improved droop controller can be effectively applied to weak grid.Additionally,different scenarios demonstrate that the improved model has good capability of suppressing low-frequency oscillation and control,and the reliability can be effectively ensured for the power supply in power grid.