Harmonic selection and capacity limitation control method for active power filter

Abstract

The invention discloses a harmonic selection and capacity limitation control method for an active power filter. The control method comprises the following steps of acquiring load current signals and extracting each sub-harmonics signal of a load; according to each sub-harmonics signal of the load, calculating a current command signal, and then constituting a modulation signal by using the acquired grid voltage, the input current and the direct current side voltage of the active power filter; and finally, generating a PWM switching signal to control a switching tube of the active power filter. The selective harmonic compensation of the active power filter and the capacity limitation running when the capacity of the active power filter is less than the load harmonics can be realized, and the overload running of the active power filter is prevented, so that the performance of the active power filter and the adaptability of the active power filter under complex ad grid conditions can be greatly improved. The control method can adopt C language programming, and can be easily implemented on a DSP chip.

Description

technical field [0001] The invention belongs to the technical field of power filter control, and more specifically relates to a control method for harmonic selection and capacity limitation of an active power filter. Background technique [0002] With the rapid development of power electronics technology and the continuous emergence and maturity of various power electronic devices, flexible AC transmission, high-voltage DC transmission, microgrid and smart grid become possible. The wide application of power electronic devices will also aggravate the power quality problems of the power grid. Therefore, it is of great significance to develop high-performance active power filters to meet the needs of harmonic control. In order to improve the grid adaptability of active power filters, commercialized APFs generally have the functions of output capacity limitation and selective harmonic compensation. [0003] Chinese invention patent "A Specified Harmonic Compensation APF and It...

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Problems solved by technology

[0003] Chinese invention patent "A Specified Harmonic Compensation APF and Its Harmonic Detection and Control Method" (publication number: 103401243A) discloses an APF specified sub-harmonic detection and control method, which is similar to the DFT algorithm harmonic detection, A fundamental cycle integration is required, so the real-time performance is not good

Chinese invention patent "Active Power Filter Selective Harmonic Compensation Control Method" (publication number: 103427419A) discloses a selective harmonic compensation control method based on the current loop controller APF, eliminating the traditional APF harmonic detection link, which improves the efficiency of the algorithm, but this method cannot simultaneously limit the output current of the APF. When the load harmonic current exceeds the compensation capability of the APF, the APF will be overloaded.

The patent "Converter DC side voltage closed-loop control method and system of active power filter" is to extract the Nth harmonic through the voltage N-multiple frequency phase-locked loop and the N-multiple frequency selection transformation matrix Cn, and the algorithm is complex

Wei Xueliang of Huazhong University of Science and Technology and others introduced a method based on capacity limitation and load-based The proportional allocation active power filter control method uses the method of calculating the effective value of the command current to limit the output of a single active power filter. This method cannot simultaneously realize selective harmonic compensation

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