Method for adaptively calculating power under arbitrary frequencies

Abstract

The invention belongs to the power grid electric energy metering technical field and relates to a method for adaptively calculating power under arbitrary frequencies. The method includes the following steps that: a sampling period is set as T, voltage signals and current signals of the load end of a power grid are synchronously sampled in a timed manner, so that voltage sampling data u (t) and current sampling data i (t) at the same time point can be obtained; operating condition matching analysis is performed on the voltage sampling data u (t) or current sampling data i (t), so that N alternating current components are obtained; and alternating current voltage u1, u2,..., uN, alternating current i1, i2,..., iN, and frequencies f1, f2,..., fN of the N alternating current components are obtained through fitting and by means of an improved extended Prony method, and the active power P1, P2,..., PN and passive power Q1, Q2,..., Q3 of each alternating current component are calculated out. With the method adopted, voltage signals and current signals can be decomposed into a plurality of harmonic components of which the frequencies, amplitudes and phases are known in real time under a condition that the harmonic of a power system is complex, in particular under a condition that non-integer-order harmonic exists or the content of harmonic is complex, and therefore, the power of the alternating current components of the load end of the power system can be measured accurately. The method has the advantages of simple implementation, high accuracy and easiness in realization.

Description

technical field [0001] The invention belongs to the technical field of grid electric energy measurement, and in particular relates to an adaptive power calculation method at any frequency. Background technique [0002] With the generation of various energy-saving electrical appliances and pulsed power loads such as fast charging stations, the parameters of the power system are becoming more and more complex, which brings certain difficulties to the accurate measurement of electric energy. In terms of ensuring the stability of the power system, the control strategy can be realized by adjusting the active power and reactive power. Therefore, it is of great significance to study the power measurement method of non-integer harmonics at any frequency for the stable operation of the power system. [0003] In the actual power system energy measurement, it is usually necessary to decompose the voltage signal or current signal into the fundamental wave component and multiple harmonic...

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Problems solved by technology

[0004] Based on the analysis method of Fourier transform, the discrete Fourier transform can analyze non-integer harmonics, but due to the large amount of calculation, the hardware requirements are high, although the fast Fourier transform reduces the performance of the discrete Fourier transform. The amount of calculation, but due to the fence effect can not extract the interharmonic from the aliased spectrum; the analysis method based on wavelet transform, because the frequency division function of different wavelet filters and the difference in energy leakage are not clear, so it is necessary A scheme is proposed to realize the accurate measurement of the active power and reactive power of the AC component at the load end of the power system under the condition that the distributed power supply and power electronic devices are widely used in the power grid, so as to provide an effective control strategy for the stable operation of the power system

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