Constant-90-degree phase shift type reactive power measurement method

Abstract

The invention discloses a constant-90-degree phase shift type reactive power measurement method which solves the problem that reactive power measurement accuracy is not high. The method comprises the steps that an integral circuit 2 is used for conducting 90-degree phase shift on input alternating voltage U[IN]; a frequency signal f[UIN] of the input voltage is used as the input of a frequency / voltage conversion circuit 3; V[X] and V[Y] are connected into a first analogue multiplication circuit 4, wherein the output of the first analogue multiplication circuit 4 is obtained through the following steps that the output V[Y] of the frequency / voltage conversion circuit 3 multiplies by the output voltage V[X] of the integral circuit 2 and then is divided by the reference voltage V[R2] of the first analogue multiplication circuit 4; an input current signal I[IN] is converted through a current-voltage conversion circuit 1 to be a voltage signal to be output; a second analogue multiplication circuit 5 enables an output signal V[Z] of the first analogue multiplication circuit 4 to multiple by the output voltage signal obtained through integration of the current-voltage conversion circuit 1, and one-phase reactive power calculation is achieved. According to the constant-90-degree phase shift type reactive power measurement method, the problem that the measurement precision is not high due to the fact that accuracy changes along with frequency change when a common analog circuit method is used for measuring the reactive power is solved.

Description

technical field [0001] The invention relates to a reactive power measurement method based on a pure 90-degree phase-shifting method. Background technique [0002] Currently, reactive power measurements in transmission and distribution lines are sometimes performed with analog circuit devices. This kind of device mostly adopts the method of phase shifting to generate an additional phase difference of 90° between the measured current and the measured voltage for measurement. Most of the currently known phase shifting methods are developed and designed at a frequency of 50 Hz. When the frequency changes very little around 50Hz, the phase change of the leading phase-shifting link and the phase changing of the lagging phase-shifting link can basically cancel each other out, but the frequency compensation range of this method is limited. When the frequency changes greatly around 50Hz and reaches 45Hz or 55Hz, the additional error caused by the phase change will exceed 0.3%, whic...

AI Technical Summary

Problems solved by technology

[0003] The invention provides a pure 90-degree phase-shift reactive power measurement method, which solves the technical problem of low reactive power measurement accuracy

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