Research On Multi-index Nonlinear Robust Adaptive Control Of Uncertain Power System Based On Differential Algebraic Model

The Power system has the characteristics of strong nonlinearity,strong coupling,high dimension and wide area.At the same time,as the scale of the power grid expands year by year,the access of a large number of new energy generators and power electronic interface further increase the complexity of the power grid,making the power system full of uncertainty.Therefore,in order to enable the power grid to operate safely and stably under various conditions,various advanced control methods are gradually applied to the power system.This paper reviews the research status of nonlinear control methods and their specific applications in the power system,and deeply studies the nonlinear control methods based on feedback linearization.However,feedback linearization design is a method based on differential geometry,which requires high accuracy of the system.Therefore,scholars hardly consider the uncertain factors in the system when using this method to design the controller.How to design the controller so that the power system can still maintain stable operation in the face of the interference of uncertain factors is a subject worthy of in-depth discussion.In this paper,the MINRAC(multi-index nonlinear robust adaptive control)method is proposed for multi-input multi-output differential algebraic systems with uncertain parameters and external disturbances.Firstly,a multi-index nonlinear robust controller is designed through partial accurate linearization,and then the control law is modified through adaptive control.The controller designed by this method has excellent dynamic and static control performance.In the case of parameter uncertainty and external disturbance in the system,the MINRAC method can ensure that multiple indicators concerned by the system can be controlled at their expected values without static offset.In order to verify the effectiveness and superiority of the MINRAC method,the third,fourth and fifth chapters of this paper respectively apply the method to the valve opening and generator excitation coordination system,super capacitor energy storage braking device and generator excitation coordination system and multi-machine power system.The simulation results show that the control mechanism of the MINRAC method is the same whether it is a single-machine infinite system or a multi-machine interconnected coupled system.The output function selects the index quantities that the system cares about,such as power angle,angular frequency and terminal voltage as constraints.When the system has parameter uncertainty and external interference,the adaptive control adjusts the uncertain parameter values to force these index quantities to tend to the given expected values,so it has excellent static tracking performance.For the most serious fault of the power system such as three-phase short circuit,this method degenerates into a multi-index nonlinear robust controller by turning off the adaptive controller,which can ensure that the system is stable in a wide range,and the system has better dynamic performance.In the fifth chapter of this paper,for the change of system network parameters,although only the parameter uncertainty in the differential equation is considered in the derivation process of the MINRAC method,the network in the system algebraic constraints is not considered.However,the simulation results show that the method is still adaptable to the changes of system network parameters,which further verifies the effectiveness and superiority of the method proposed in this paper.