Method for detecting harmonic wave and reactive current based on spatial transformation of voltage vectors

Abstract

Aiming at a problem that an ip-iq algorithm cannot precisely acquire fundamental wave positive sequence active currents under the conditions of non-ideal power network voltages, the invention provides a method for detecting a harmonic wave and a reactive current based on spatial transformation of voltage vectors. The method comprises the steps of performing coordinate transformation on currents and voltages on an ip-iq algorithm channel to acquire phase information of three-phase fundamental wave positive sequence voltages; defining a p-q coordinate system; defining correct positive sequence active components and positive sequence reactive components by using the projection of a current vector on a voltage vector and a normal line thereof under the coordinate system; then accurately solving fundamental wave positive sequence active components, fundamental wave positive sequence reactive components, fundamental wave negative sequence active components and fundamental wave negative sequence reactive components in a load current by taking the correct positive sequence active components and the positive sequence reactive components as reference volumes and using an improved ip-iq algorithm; and popularizing the detection of the four fundamental wave current magnitudes into the detection of any sub-harmonic current magnitude to form a current detection system under the conditions of non-ideal voltages so as to provide reasonable reference instruction currents for various compensation requirements.

Description

technical field [0001] The invention relates to a harmonic and reactive current detection method based on voltage vector space transformation. technical background [0002] The application of rectifiers, frequency conversion speed control devices, electric arc furnaces and various power electronic equipment in the distribution network continues to increase. The nonlinear, impact and unbalanced power consumption characteristics of these loads have caused serious pollution to the quality of power supply. Has become the main reason affecting the power quality. They inject a large number of harmonics and reactive power generated into the power grid, and the voltage of the power grid has been polluted into a distorted and asymmetric non-ideal voltage source, which seriously affects the safety of the power grid and the service life of electrical equipment. Therefore, it is possible to accurately detect various components of the current under these distortions and asymmetric grids...

AI Technical Summary

Problems solved by technology

DFT algorithm can only detect harmonic current, and the calculation is complicated

The p-q algorithm can only accurately detect the fundamental reactive current when the three-phase voltage is sinusoidal and symmetrical, i p -i q The algorithm can accurately detect the fundamental positive-sequence component of the load current when the grid voltage is distorted, but cannot accurately obtain the active and reactive components of the fundamental positive-sequence current

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