Method and device for measuring low-frequency oscillation signal in power system

Abstract

The invention discloses a method and device for measuring a low-frequency oscillation signal in a power system. The steps of the method include: S1. Acquire the collected three-phase voltage signal in the power system, and based on the pre-built low-frequency oscillation three-phase signal model, the acquired The three-phase voltage signal is converted into a complex signal sequence; S2. Discrete Fourier transform is performed on the complex signal sequence obtained by step S1 conversion to obtain a complex spectrum, and the obtained complex spectrum is estimated using an interpolation method to estimate the dynamic parameters in the complex spectrum , to obtain the final low-frequency oscillation signal output. The invention has the advantages of simple realization method, low cost, high measurement accuracy and test efficiency, strong anti-interference and the like.

Description

technical field [0001] The invention relates to the technical field of power system parameter measurement, in particular to a method and a device for measuring a low-frequency oscillation signal of a power system. Background technique [0002] Accurate estimation of power grid parameters is an important basis for power metering, power quality detection, and relay protection. Disturbances in the power system, such as faults, on / off of heavy loads, disconnection of generators, line switching, etc., can cause the rotor angle between generators to oscillate and cause low-frequency oscillations in the grid. How to realize the accurate and rapid measurement of power grid parameters under the condition of low frequency oscillation plays a crucial role in maintaining the stable operation of the power system. [0003] The commonly used measurement methods for power grid parameters are: 1. Detection algorithm based on sinusoidal signal model; 2. Periodic method and its improved algor...

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Problems solved by technology

Low-frequency oscillation is a kind of balance phenomenon in three-phase power system. In the scene of low-frequency oscillation, the voltage and current signals in the power grid are no longer steady-state signals, and their amplitudes will fluctuate periodically. Control will further lead to power oscillation between systems, which will have adverse effects on transmission lines and electrical equipment, and damage the safety and stability of the system. Therefore, how to accurately and quickly estimate the parameters of the oscillation signal is crucial to assess the severity of low-frequency oscillations , and the above-mentioned traditional measurement methods cannot timely and accurately realize the measurement of low-frequency oscillation signals

[0006] In order to realize timely and accurate measurement of low-frequency oscillation signals, the following methods are mainly used in the prior art: 1. Combining the Prony method with digital filtering, so that the noise immunity is improved compared with the traditional Prony method; 2. Based on Kalman filtering 3. Iterative filtering algorithm, this method can achieve high Accuracy measurement, but the error is large when the frequency deviation is large and the amplitude changes dynamically; 4. Although the wavelet transform method can be applied to dynamic signal analysis, it has a large amount of calculation, and there will be problems of insufficient real-time performance; 5. , Taylor Fourier method, simplified calculation through Taylor series expansion, high precision in steady state, strong harmonic suppression ability, fast response in dynamic state

[0007] However, in the above-mentioned various measurement methods for low-frequency oscillating signals, single-phase signals are used to realize parameter estimation. In power systems, the three-phase is usually considered as a whole, and the balance characteristics of the three-phase system need to be considered. Therefore, The above-mentioned various measurement methods for low-frequency oscillation signals are still unable to accurately measure three-phase signals in power systems, especially when the number of sampling points is small, not only the measurement accuracy is not high, but also the anti-noise performance and anti-interference performance are poor. In the case of noise interference, it is even difficult to measure the three-phase low-frequency oscillation signal in the system

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