Method for controlling harmonic currents in synchronous rotating reference frame by several times

Abstract

The invention relates to a method for controlling harmonic currents in a synchronous rotating reference frame by several times. Compensated harmonic currents at a certain time are converted to the synchronous rotating reference frame with the same times of rotating speeds and directions, harmonic instruction current information of an SFR is fully utilized, AC disturbance quantity brought by other nonsynchronous current components in the SFR is removed through a simple algorithm, so that the DC quantity corresponding to the compensated currents at the time in the SFR is extracted, and PI static-error-free decoupling control is achieved. The stability margin and the dynamic response speed of a control system can be effectively improved, and the steady state errors of the system are removed.

Description

technical field [0001] The invention relates to a stepwise control method of harmonic current in a synchronous rotating coordinate system. Background technique [0002] Active Power Filter (APF) is widely used in harmonic suppression and reactive power compensation of distribution network due to its advantages of fast dynamic response, not easy to resonate with grid impedance, and not affected by grid frequency fluctuations. Power Quality Governance Field]. [0003] At present, in the engineering application of APF, in order to enhance the flexibility of harmonic compensation and improve the effect of harmonic compensation, the harmonic current sub-compensation method is usually adopted, that is, only a few specified sub-harmonics in the load current are compensated. Harmonic current sub-compensation control includes two links of detection and control, and there are usually two implementation schemes: [0004] First, batch detection and comprehensive control. [0005] Thi...

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Problems solved by technology

The main problem of this method is that when compensating more than two kinds of harmonic currents at the same time, since the SFR not only includes the DC amount, but also includes the AC amount formed by the current component that is not synchronized with the SFR, at this time, it is still impossible to truly realize the PI wireless Static difference control target

For this reason, how to obtain the DC flow in SFR becomes the key issue to determine the performance of this method! The literature proposes a current control method for specified sub-harmonics in a multi-synchronous rotating coordinate system, which can achieve no static error control for specified sub-harmonics, but this method must introduce a low-pass filter on the current closed-loop control channel of each SFR , to filter the error current to obtain a DC signal, and the low-pass filter is usually equivalent to the first-order and above inertial link in the control system, causing the signal phase to lag, thereby reducing the stability margin of the closed-loop control system

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