Design Of Excitation Adaptive Control System For Multimachine Power System With SVC

The multi-machine power system is a large-scale interconnected system with multidimensional,strongly coupled and highly nonlinear characteristics.Therefore,it is more susceptible to instability factors,such as internal parameters uncertainty,external interference and multi-machine interconnection coupling,which increases the control difficulty.Recent research on multi-machine power system control issues has not only introduced various advanced intelligent control algorithms,but also added more flexible AC power transmission equipment represented by Static Var Compensator(SVC).Although the addition of the SVC improves the stability of the power system,because the excitation controller and the SVC controller are usually designed independently and do not consider the interaction between the two,which may have negative effects on the system control and even cause system instability.Therefore,it is very necessary to carry out coordinated control of the multi-machine power system and the SVC.In this paper,for the multi-machine power system equipped with a static reactive power compensator,the robust adaptive nonlinear control of the system with internal uncertainty,external interference and multi-machine interconnection coupling is studied.The main work of the paper is described below:(1)The multi-machine interconnected power system equipped with SVC device is modeled.First of all,consider factors that are difficult to accurately measure in actual engineering situations,such as the system's damping coefficients and transient electromotive force,and treat them as uncertain parameters.Then,the unknown external disturbances and the coupling term in multi-machine power system are considered.(2)For the established nonlinear system model,an adaptive dynamic surface sliding mode controller is designed to meet the prescribe output tracking performance.First,the combination of adaptive dynamic surface and sliding mode control method enhances the robustness and avoids the "differential explosion" problem in the backstepping method.Then,the tracking error performance functions are introduced,so that the prescribed performance of the tracking error can be realized.The experimental results show that the proposed control method is more effective compared with the traditional adaptive backstepping control method,the adaptive dynamic surface control method and adaptive sliding mode control method.(3)Based on the dynamic surface control method,the composite learning method is used to improve the fuzzy logic system.The state predictor is introduced.The prediction error is used to apply an additional adjustment information for updating the weight vector of the fuzzy logic system,which improves the approximate accuracy.Then,the disturbance observer(DOB)is introduced to estimate the compound disturbances which composed of the approximation error of the fuzzy logic system and the external disturbances of the system.This further improves the robustness.Finally,simulation experiments verify the effectiveness of the proposed control scheme.In summary,this paper proposed two adaptive control schemes for a multi-machine power system with SVC.Through the StarSim power system real-time simulation experiment,the proposed methods have a good control effect,which can guarantee the stable operation of the multi-machine power system.