On-line Monitoring Method of Low Frequency Oscillation in Power System Based on Combination of Change Point Detection and Prony Method

Abstract

The invention provides a method used for online monitoring of low-frequency oscillation of an electric power system and based on combination of change-point detection and a Prony method. The method comprises steps as follows: on the basis of a WAMS (wide area measurement system), converting power angle data of all observation units in the system into relative power angle values based on reference units; monitoring abrupt change of relative power angles of the observation units; in response to the abrupt change, constructing a time sequence by the aid of real-time data of relative power angle values; performing change-point detection, and detecting types causing dynamic response of the system; executing set processing in response to different types causing the dynamic response of the system: performing Prony algorithm based system mode analysis, or returning to the former steps for continuously monitoring the abrupt change of relative power angles of the observation units and processing a change-point detection result. With the adoption of the method, the defects of a conventional low-frequency oscillation online monitoring system can be overcome, the low-frequency oscillation state of the system is accurately judged, meanwhile, the influence caused by non-stationary performance of an oscillation starting early signal can be avoided, and the precision and the reliability of system mode information acquired with the Prony method are improved.

Description

Technical field [0001] The invention relates to the field of power system low-frequency oscillation monitoring and analysis, in particular to a power system low-frequency oscillation online monitoring method based on the combination of change point detection and Prony algorithm. Background technique [0002] At present, low-frequency oscillation has become a prominent problem that limits the power transmission capacity between interconnected power grids and affects the safe and stable operation of the system. Low-frequency oscillation is mainly manifested as the continuous relative swing between the generator rotors due to insufficient damping after the synchronously operating power system is disturbed. Electrically, it is the continuous oscillation of generator power angle, tie-line power, and bus voltage. The frequency is generally between 0.1 and 2.5 Hz. The timely detection of low-frequency oscillations of the power system and effective measures to quickly quell the oscillat...

AI Technical Summary

Problems solved by technology

[0004] In view of the shortcomings of inaccurate results and large amount of calculations caused by direct use of spectrum analysis methods such as Prony in the existing low-frequency oscillation on-line monitoring, the purpose of the present invention is to provide a low-frequency oscillation of power systems based on the combination of change point detection and Prony method In the online monitoring method, change point detection is used to effectively distinguish between transient stability and weakly damped low-frequency oscillation problems. After entering the stable oscillation, the Prony method is used to obtain more reliable modal information to prevent the monitoring system from giving unreliable system modal parameters. information

Images