Research On Nonlinear Control Method Of Power System With Static Synchronous Compensator

With the rapid development of China's interconnected power grid and the large investment in power electronic equipment,the stability of power systems has become increasingly prominent.Improving the stability of the power systems is one of the key issues in the construction of smart grids.The Static Synchronous Compensator(STATCOM)is a third-generation flexible AC transmission system(FACTS)device with wide adjustment range,small size,and rapid response.Installing STATCOM in the power system can not only reduce losses and suppress harmonics,but also can improve the static and transient stability of the power system.After installing STATCOM,the nonlinear characteristics and uncertainty of the system will affect the performance of the control system,so its control strategy needs to be studied.Therefore,this paper adopts the nonlinear control method to design the coordinated controller for the uncertain parameters and disturbances in the nonlinear coordinated control of power system including STATCOM.The specific research content is as follows:(1)Aiming at the problem that the stability of the generator excitation and STATCOM coordinated control system is affected by the unknown disturbance,a generator excitation-STATCOM nonlinear fuzzy sliding mode coordinated control(FSMCC)method is proposed.Firstly,the mathematical model of STATCOM and generator excitation coordination control is established and accurately linearized.Then the controller design is based on fuzzy control theory and sliding mode control theory,and the chattering problem of sliding mode variable structure control is solved by the designed one-dimensional fuzzy controller.The simulation results of MATLAB show that the designed fuzzy coordination controller can quickly stabilize the system state variables(drive the generator power angle and voltage back to steady state),which can effectively improve the system transient performance.(2)Considering that the valve control system has good control effect in improving the dynamic quality of the system,a nonlinear mathematical model of STATCOM,generator excitation and turbine adjustment is established.A nonlinear variable structure coordinated control(VSCC)method.based on inverse system theory and adaptive variable structure control is proposed.And using the power approach law and the saturation function to design a new approach law,eliminate the chattering problem of variable structure control.The simulation results of MATLAB show that the designed coordination controller can effectively improve the transient performance of the system compared with the separate control of generator excitation-turbine valve and STATCOM.(3)Aiming at the problem of parameter uncertainty and unknown disturbance affecting system stability in generator excitation and STATCOM coordinated control system,an I&I based STATCOM and generator excitation nonlinear backstepping adaptive coordinated control(BACC)is proposed.The algorithm does not perform any linearization processing on the nonlinear coordinated control system,and the design of the parameter estimation law does not need to follow the traditional deterministic equivalence principle.The simulation results of MATLAB show that the designed BACC can improve the transient performance of the system compared with the traditional backstepping method,and can ensure that the input variables such as generator power angle,rotor angular velocity and transient potential have the control strategy under the design control strategy.Good dynamic and static performance to improve the transient performance of the control system.There are 26 figures and 68 references in this paper.