Calculation method for sub-frequency harmonic compensation of APF under multiple synchronous rotating reference frames

Abstract

The invention discloses a calculation method for sub-frequency harmonic compensation of an APF under multiple synchronous rotating reference frames. The calculation method comprises the following steps that after two-phase Clarke transformation is carried out on system voltage, positive-sequence Park transformation and negative-sequence Park transformation are carried out respectively, so that DC components VPd and VPq under a positive-sequence coordinate system and DC components VNd and VNq under a negative-sequence coordinate system are obtained, positive-sequence and negative-sequence decoupling filtering processing is carried out on the DC components VPd and VPq under the positive-sequence coordinate system and the DC components VNd and VNq under the negative-sequence coordinate system at a D_Couple module, and therefore the feedforward quantity of reference voltage output by the APF is obtained. Phase-locked loop calculation is used for obtaining the phase of the system voltage, so that the phase of the feedforward quantity of the reference voltage output by the APF is provided. Compared with the prior art, the method has the advantages that the calculation method for sub-frequency harmonic compensation of the APF under the multiple synchronous rotating reference frames prompts that each order of harmonic current is independently processed and quickly responded, and it is guaranteed that compensation for each order of harmonic is independently set.

Description

technical field [0001] The invention relates to the technical field of APF type inverter control, in particular to a calculation method for sub-harmonic compensation of a multi-synchronous rotating coordinate system APF. Background technique [0002] The large-scale development and application of power electronic equipment has brought harmonic currents to the power grid. The existence of harmonics not only affects power quality, but also leads to low equipment utilization, high noise, and increased calorific value. The disturbance caused will affect their normal work. Therefore, in recent years, an industry specializing in harmonic control has been formed, and the key equipment is the active power filter (APF). The basic principle of APF is to output the harmonic current opposite to the harmonic current in the load current to the grid to neutralize the harmonic current in the system, and the key link in APF is to separate the harmonic current in the load and convert it It ...

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Problems solved by technology

The basic principle of APF is to output the harmonic current opposite to the harmonic current in the load current to the grid to neutralize the harmonic current in the system, and the key link in APF is to separate the harmonic current in the load and convert it It is the reference voltage of the voltage source inverter (VSR) device. After years of research in the industry, several different methods have been accumulated: FFT, instantaneous reactive power IP-IQ method, fundamental wave component elimination method and other methods. The common The characteristic is that all calculations are carried out in the fundamental wave coordinate system, and it is carried out based on the concept of fundamental wave cycle average, so for the harmonic current whose changing speed is much higher than the fundamental wave current, the lag is serious, which greatly affects the treatment effect. For higher order harmonics, it may also cause amplification or oscillation due to phase lag, which may cause system safety problems

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