The Method of Obtaining the Single-phase Voltage Phase of Power Network

Abstract

The invention relates to a method for calculating a single-phase voltage phase, in particular to a method for obtaining the single-phase voltage phase of a power grid, and solves a problem that a conventional technical scheme for obtaining the single-phase voltage phase of the power grid is low in accuracy of phase acquisition, slow in response, and sensitive to changes in system frequency, and isnot suitable for applications with high dynamic performance requirements. The method is realized by the following steps: 1) collecting the grid voltage Us and obtaining DC components vd and vq in a rotating coordinate system; 2) obtaining the DC components vd<-> and vq<-> with the second harmonic components eliminated; 3) using the vq<-> and a value of zero as inputs to form a PI closed loop controller; 4) introducing angular velocity [omega] into the output of the PI closed-loop controller to form a feedforward disturbance, comparing the feedforward disturbance with the output of the PI controller and then inputting a compared result to an integration link. The method uses a software-implemented closed-loop phase-locked loop, and is particularly suitable for the control of a PWM rectifier in an electric locomotive, and can also be used for obtaining the single-phase voltage phases in other environments.

Description

technical field [0001] The invention relates to a calculation method for a single-phase voltage phase, in particular to a method for obtaining a grid single-phase voltage phase. Background technique [0002] In the electric locomotive, in the control of PWM rectifier, in order to realize the active and reactive power control of the grid side, it is necessary to dynamically obtain the phase information of the grid voltage. One of the existing methods for obtaining the phase of a single-phase voltage is an open-loop phase-locked loop scheme based on a low-pass filter, which uses the phase-locked loop to phase-lock the grid voltage. In practical applications, especially in electric locomotives, the power quality and environment of the power grid are not ideal, and there are problems such as phase mutation, voltage drop, frequency change and harmonic pollution. The open-loop phase-locked loop scheme based on low-pass filter The phase acquisition accuracy is not high, the respon...

AI Technical Summary

Problems solved by technology

In practical applications, especially in electric locomotives, the power quality and environment of the power grid are not ideal, and there are problems such as phase mutation, voltage drop, frequency change and harmonic pollution. The open-loop phase-locked loop scheme based on low-pass filter The phase acquisition accuracy is not high, the response is slow, and it is sensitive to system frequency changes, so it is not suitable for occasions with high dynamic performance requirements

The second method is a closed-loop phase-locked loop scheme based on a multiplicative phase detector. For better control, this method filters out the double frequency component, and usually adds a low-pass filter, thereby introducing phase delay and amplitude attenuation. The performance and accuracy of the ring are greatly affected