Research On Early Warning System Of Power System Low Frequency Oscillation

At present,the low-frequency oscillation monitoring analysis of the Wide Area Measurement System(WAMS)is mainly used for alarm analysis after the occurrence of an oscillation event,and does not fully exert its early warning effect.Therefore,the safety early warning research on the low frequency oscillation phenomenon provides reliable early warning indicators for the dispatching operators,which has great practical significance for the safe and stable operation of the power system.In this paper,combined with modern signal processing methods,an in-depth study on the safety early warning integrated system of low frequency oscillations in power grids is carried out.This paper first introduces the basic principle and architecture of the WAMS system.According to the data characteristics in the wide-area measurement system,the input signal of the appropriate low-frequency oscillation online identification algorithm is selected.Aiming at the shortcomings of WAMS system data processing and the actual noise,the independent component technology(ICA)is introduced for filtering denoising,and the preprocessing method based on measured data of WAMS system is elaborated.Secondly,combined with the characteristics of the low-frequency oscillating signal,the fluctuation trend and the impact on the power grid,a comprehensive warning comprehensive index system including the signal frequency,the weakest damping ratio of the dominant mode,the peak value of the power oscillation,and the peak-to-peak duration are constructed.The early warning indicators complement each other to verify each other,analyze the actual safe operating state of the power grid,and judge whether the power grid is in a stable state on the standard of the early warning threshold.The evaluation levels are set for the four early warning indicators,and the analytic hierarchy process and fuzzy comprehensive evaluation are combined to establish an efficient comprehensive evaluation system for grid security early warning,combined with online identification and rapid warning to achieve comprehensive security early warning.purpose.According to the established early warning indicator system,the general framework of low-frequency oscillation early warning technology for power system based on WAMS system is proposed.Finally,an early warning software with real-time computing function and fault search function was developed in combination with practical applications.Through the simulation example analysis,under the various disturbances of the power grid,the various early warning indicators can quickly and accurately give the safe operation status of the power grid,and verify the feasibility and correctness of the above-mentioned safety early warning indicators analysis.