Voltage control method based on phase-lock loop of decoupling multi-coordinate system

Abstract

The invention relates to a voltage control method based on a phase-lock loop of a decoupling multi-coordinate system, belonging to the technical field of industrial control. The steps are as follows: measuring the system voltage and the voltage and the current of a capacitor on the output side of an inverter of a dynamic voltage restorer; establishing a model of the phase-lock loop of the decoupling multi-coordinate system; calculating the reference value of the compensating voltage of the dynamic voltage restorer according to detected signals; and establishing a strategy for controlling the dynamic voltage restorer, realizing bi-loop control of voltage and current, and obtaining PWM pulse which drives and controls a full-control switch to switch on or switch off. The invention realizes the purpose that the dynamic voltage restorer can quickly and accurately inject the compensating voltage so as to keep the load side voltage unchanged when the system voltage suffers three-phase unbalance, distortion, sag, short-time single-phase fault, etc.

Description

technical field [0001] The invention relates to a voltage control method in the technical field of electric power engineering, in particular to a voltage control method for a dynamic voltage restorer based on a multi-coordinate system phase-locked loop. Background technique [0002] For the problem of voltage control, the commonly used methods at home and abroad are: peak voltage method, FFT method, wavelet transform method, state space matrix method, dq transformation method based on instantaneous reactive power theory, among which the peak voltage method has at least half a cycle time delay, and it is easily disturbed by noise, and at the same time, it cannot detect the jump of the phase angle; the FFT method is only suitable for the case of voltage symmetry; It can only be applied in power quality monitoring devices; the state space matrix method needs to know the accurate expression of the voltage signal, and the actual signal contains a variety of harmonics. When the vo...

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Problems solved by technology

[0004] 22, NO.2, MARCH 2007) proposed a decoupling dual-coordinate system phase-locked loop based on cross-decoupling modules. This method transforms the three-phase voltages of the system into positive and negative sequence coordinates respectively, and realizes positive and negative sequence components. Although this method eliminates the detection error of the traditional phase-locked loop, it is only applicable when the system voltage is three-phase symmetrical or three-phase unbalanced and has no zero-sequence component; when the harmonic content of the system voltage is relatively large Or when a single-phase fault occurs and contains a zero-sequence component, the angle error of the phase-locked loop obtained is relatively large, and the amplitude and phase of the fundamental positive-sequence component cannot be accurately obtained, so that an accurate reference compensation voltage cannot be obtained, and dynamic voltage recovery cannot be realized. device function

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