Three phase electrical measurement method based on positive-sequence component computation

Abstract

The invention discloses a three phase electrical measurement method based on positive-sequence component computation. The method comprises: 1, adopting a mutual inductor to collect voltage signals and current signals of a three phase line, and processing the collected voltage signals and current signals to form low voltage analog signals of voltage and current; 2, passing the low voltage analog signals through an anti-aliasing filter to form signals; 3, converting the signals obtained in step 2 into digital signals; 4, utilizing discrete Fourier transform computing method to obtain frequency domain components, and then utilizing sequence component decomposition method to obtain positive sequence, negative sequence and zero sequence components of fundamental wave voltage and current; and 5, computing the digital signals comprehensively after decomposing sequence components of fundamental wave voltage and current to form the parameters such as fundamental wave positive sequence active power, fundamental wave positive sequence active power reactive power and corresponding fundamental wave positive sequence active electric quantity and fundamental wave positive sequence reactive electric quantity, and finally computing electric quantity of the line by using the fundamental wave positive sequence active electric quantity and fundamental wave positive sequence reactive electric quantity.

Description

technical field [0001] The invention relates to a three-phase electric quantity measurement method, in particular to a three-phase electric quantity measurement method based on positive sequence component measurement. Background technique [0002] With the development of science and technology, various power electronic nonlinear and asymmetrical loads are put into use. For example, the nonlinear loads on the site of iron and steel enterprises include: large-scale variable-frequency speed-regulating motors, heavy-duty commutator motors, and large-capacity inductors and capacitors. charging and discharging process, etc. Due to the nonlinearity, asymmetry and volatility of these loads, the power system generates a large number of harmonics, causing serious distortion of the grid voltage waveform and injecting a large amount of negative sequence current into the grid. They not only cause pollution to the power supply system, constitute a hazard to power equipment, but also affe...

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Problems solved by technology

Since the electronic energy meter does not use an inductive measuring mechanism, it uses a multiplier to multiply the voltage and current to complete the measurement of electric power, which improves the measurement accuracy, reduces power consumption, and enhances the overload capacity. However, the traditional electronic energy meter The energy meter does not consider the reasonable measurement problem in the case of harmonics and negative sequence, resulting in the measurement results of power supply companies and users sometimes being too large or too small in the case of harmonics and negative sequence, and the measured results cannot reflect the measurement. rationality

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