Research On Low Frequency Oscillation Suppression Of Power System Considering Control Network Delay

In recent years,with the continuous expansion of the scale of the power grid,the problems caused by the low-frequency oscillation mode of the power system have become increasingly prominent,which has seriously affected the safe and stable operation of the power grid.The application of the wide-area measurement system brings a new opportunity for the suppression of low-frequency oscillations in the interval—wide-area damping control method.At present,wide-area damping control has been increasingly regarded as one of the most effective and promising methods for suppressing low-frequency oscillations in power systems.How to deal with the delay of the wide area signal in the acquisition and transmission process does not affect the performance of the controller and choose the appropriate electrical quantity among the electrical quantities of the entire system to achieve the maximum control effect at the minimum control cost,which is currently hindering wide area damping Two major problems with control applications.Solving the above problems mainly depends on the feedback signal of the wide-area damping control and the selection of the control location,the communication delay solution and the design of the controller strategy.Aiming at the time delay problem in power system wide-area damping control,this paper focuses on the optimization method of the controller's feedback signal time delay compensation and optimization selection.The main research contents are as follows:1)First,a multi-machine power system model is established.On this basis,the influence of communication delay and feedback signal selection on power system stability is analyzed by a small interference stability analysis method,and the delay and signal selection factors are verified through simulation experiments.Impact.2)Aiming at the problem of deterioration and stability of wide-area damping control caused by the information transmission delay and its changes in the existing power system control network,an algorithm based on improved Prony predictive compensation is designed for the acquisition signal with delay For prediction compensation,the second-order derivative method is used to determine the best effective rank of the prediction model to improve the accuracy of the prediction compensation algorithm,and the prediction step of the prediction model parameters is determined in consideration of the actual situation of the delay variation.Through the electric damping control experiment,it is proved that the proposed method can effectively compensate the signal under the conditions of timing delay and variable delay,and has a higher delay adaptability advantage than the traditional method.3)Aiming at the problem of power system wide area damping controller signal selection optimization and dimensionality reduction,a two-stage screening method based on identification is designed.First quantify the influence of wide-area damping controller selection signal on system stability,and then design the optimal selection algorithm of feedback signal according to linear system theory;through the equivalent conversion of the mode component amplitude in the index calculation formula,the design converts the screening index to Adapt to the dimensionality reduction model calculation method to avoid the "dimension disaster" problem of traditional methods applied to multi-machine systems.Finally,the effectiveness of the method is verified by the electric damping control experiment.The proposed method can effectively select the unit maximum damping ratio and the minimum impact on other control loops.The scheme designed in this paper is simple and efficient,and it is a useful attempt in the field of low-frequency oscillation suppression in the interval.It has certain research significance and practical value.In the end,this paper makes a prospect for the future research of power system monitoring and control based on wide area measurement system.