Low frequency oscillation on-line analysis and early warning method of electric power system

Abstract

A low frequency oscillation on-line analysis and early warning method of an electric power system includes the steps of acquiring and preprocessing a frequency signal, estimating frequency and a damping ratio of an oscillation mode, determining a dominant mode, and performing early warning of a dominant modal state. The method is based on self-adaption detrend processing of empirical mode decomposition, steady state and nonlinear components of system response under stimulating of disturbance in different strengths can be eliminated, and dynamic oscillation characteristics of the system response can be kept; an expanding stage Yule-Walker method is combined to estimate the system oscillation mode, energy of the oscillation mode is calculated, and the dominant mode of the system is determined; according to the strength of damping, safety, alert or emergency information of system oscillation is sent. The method can be applied to distribution network frequency signals, practical value is high, an estimated result is accurate, free response to the system and random response to the system can be performed uniformly, the method is applicable to on-line analysis of low frequency oscillation modes of a large-scale electric power system, and the method provides oscillation early warning information to a control center timely.

Description

technical field [0001] The invention relates to a power system monitoring method, in particular to an online analysis and early warning method for low-frequency oscillation of a power system. Background technique [0002] While improving the reliability of power grid operation and the economy of resource utilization, the interconnection of power systems has also brought new hidden dangers. Low-frequency oscillations of power systems have occurred both at home and abroad. Low-frequency oscillations usually occur on long-distance, heavy-duty transmission lines, or weak tie lines of interconnected systems, and are more likely to occur under the conditions of a fast-response high-amplification excitation system. The time constant of the fast excitation regulator is greatly reduced, which effectively improves the voltage regulation characteristics, but the additional damping generated by it is negative, which offsets the inherent positive damping of the system itself, so that the...

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Problems solved by technology

[0004] In order to overcome the deficiency that the existing power system low-frequency oscillation analysis method cannot realize the unified analysis of free response and random response, the present invention provides an online analysis and early warning method for low-frequency oscillation of power system, which uses the system frequency signal to estimate the low-frequency oscillation mode and perform early warning , can analyze the characteristics of low-frequency oscillation more accurately, and issue reliable early warning information, so that the power sector can take corresponding measures in time to suppress the occurrence of severe low-frequency oscillation phenomena in the power grid, and effectively improve the stability and safety of power grid operation

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