Sliding mode control method of novel three-phase three-wire system active filter

Abstract

The invention discloses a sliding mode control method of a novel three-phase three-wire system active filter, which is characterized by comprising the following steps of: 1, detecting three-phase harmonic current signals in load currents by a load current harmonic detection module; 2, detecting actual three-phase compensation current signals of a compensation circuit by a compensation current detection module; 3, subtracting corresponding three-phase compensation current signals by the three-phase harmonic current signals respectively to obtain tracking control errors of harmonic currents; 4, utilizing tracking control errors of each phase current, differential coefficients of the errors and integration of the errors to form a sliding mode surface of a sliding mode structure; and 5, carrying out PWM (pulse width modulation) on output of a sliding mode controller, and generating control signals to switching on / off of an IGBT (insulated gate bipolar transistor). The sliding mode control method is simple in computation and easy to realize, and can be used to effectively reduce the tracking errors of the harmonic currents, weaken buffeting of supply currents, reduce harmonic contents of compensated supply currents, and improve the control accuracy of the active filter.

Description

technical field [0001] The patent of the present invention belongs to the technical field of active power filter, and in particular relates to a sliding mode variable structure control method of an active power filter. Background technique [0002] In contemporary society, the large-scale application of various nonlinear and time-varying electronic devices such as inverters, rectifiers and various switching power supplies has brought about power quality problems in power systems. The so-called power quality problems mainly refer to the low power factor of the grid, waveform distortion, surge, phase distortion and so on. Active Power Filter (APF—Active Power Filter) can be used for power system harmonic suppression and reactive current compensation. Its principle is to make the compensation circuit generate harmonic current Compensation current with equal magnitude and opposite direction to offset the harmonic current in the load current. In actual operation, it is equival...

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Problems solved by technology

Although the traditional hysteresis comparison method has the advantages of fast dynamic response, good robustness, and strong adaptability to loads, etc., the power supply current chattering phenomenon is serious, the tracking error of harmonic current is relatively large, and the harmonic content of power supply current is relatively high. , which greatly affects the control accuracy of the active power filter

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