Research On Small Disturbance Stability Control Of Power System Considering Stochastic Wide-Area Signals Time-Delay

The problem of inter-area low-frequency oscillation is not only harmful to large-scale power transmission,but also seriously affects the safety operation of the power system.Widearea measurement system based on phasor measurement unit can acquire wide-area signals with good observability for inter-area low-frequency oscillation,which establishes foundation for constructing wide-area closed-loop damping control system and improving the stability operation level of the power system.The characteristics of wide-area signals in transmission process must be considered.In order to analyze the small disturbance stability of power system with time-delay and reduce the negative impact of time-delay of wide-area signals on the performance of wide-area damping controller.Therefore,the wide-area damping closed-loop control system is studied in this thesis.The control and analysis method of small disturbance stability in power system considering wide-area signals stochastic time-delay is studied in detail.The specific research includes establishment of co-simulation platform,small disturbance stability analysis of time-delay system,design of robust controller with time-delay and predictive compensation method for time-delay signals.Firstly,considering that the wide-area closed-loop control system has typical characteristics of cyber-physical system,the co-simulation method of information network simulation software OPNET Modeler and power system simulation software MATLAB are studied and a preliminarily analysis of the influence of wide-area signals time-delay is based on the co-simulation platform.The construction method of the co-simulation platform is introduced.Then a classical two-area four-machine Kundur system for studying low-frequency oscillation is established in the co-simulation platform.The time domain simulation under different time-delay scenes are carried out and the Prony method is used for analysis the results.Secondly,the small disturbance stability of power system is studied considering the widearea signals with probabilistic distributed time-delay.A small disturbance stability calculation model of power system considering the probability distribution of signals time-delay is established and a time-delay sensitivity calculation method based on damped torque analysis method is proposed.The small disturbance stability of power systems with different probability distributions of time-delay are calculated by Gram-Charlier expansion.Finally,a simple parameter optimization method of controller considering probability distribution of time-delay is proposed.The simulation results show that the proposed method is faster than Monte Carlo simulation and more effective to large-scale system.Then,considering the stochastic wide-area signals time-delay,a parameter robust design method for wide-area power system stabilizer based on sensitivity is proposed.Firstly,the basic concepts of multi-objective optimization are introduced and the improved algorithm is proposed.Then the parameter is solved by the improved multi-objective particle swarm optimization algorithm.The validity of the design method is verified by simulation.At last,considering that the wide-area signals in practical scenarios not only has time delay,but also is affected by noise,packet loss and other problems.A wide-area signals predictive compensation method for power system considering stochastic time-delay and packet loss is proposed.Firstly,the unified predictive compensation model considering both time-delay and packet loss are studied and grey Verhulst algorithm is introduced into the prediction and compensation of wide-area signals in power system.In order to solve the problem of wide-area signals noise in practical system,using complete ensemble empirical mode decomposition with adaptive noise method to filter wide-area signals.Based on the above model,a wide-area signals prediction compensation method considering signals noise,time-delay and packet loss is proposed.The effectiveness of the predictive compensation algorithm is verified by time simulation.