Hybrid active power filter with high voltage chain-type structure and control method thereof

Abstract

The invention discloses a hybrid active power filter with a high voltage chain-type structure and a control method thereof. The hybrid active power filter comprises chain-type structure converters, filter reactors and high-pass filters, and is characterized in that each chain-type structure converter is a structure converter with a bypass, each chain-type structure converter adopts an H-bridge module, and DC-side capacitors are mutually independent; and the chain-type structure converters are connected with the high-pass filters in parallel through the filter reactors, then connected to a power grid and respectively connected with one phase in the power grid. The control method is based on the filter structure, and comprises harmonic wave frequency division detection, active power filter harmonic closed-loop control, reactive compensation and APF average DC voltage control, and DC voltage balance control. The hybrid active power filter disclosed by the invention has the advantages of simple and compact structure, low cost, good operation reliability, excellent performance and the like.

Description

technical field [0001] The invention mainly relates to the field of power filters in high-voltage systems, in particular to a hybrid active power filter based on a high-voltage chain structure and a control method thereof. Background technique [0002] At present, active power filters used in high-voltage systems mainly adopt the following three methods: [0003] One is to use a three-phase full-bridge converter to generate compensating harmonic current, and then connect it to the high-voltage power grid after being boosted by a transformer. The disadvantage of this method is that the three-phase full-bridge circuit is limited by the blocking voltage of the IGBT device and cannot directly output high voltage. As a result, in large-capacity applications, multiple three-phase full-bridge circuits need to be connected in parallel on the low-voltage side, resulting in a very large low-voltage bus current. The huge low-voltage current not only makes it difficult to control the l...

AI Technical Summary

Problems solved by technology

[0003] One is to use a three-phase full-bridge converter to generate compensating harmonic current, and then connect it to the high-voltage power grid after being boosted by a transformer. The disadvantage of this method is that the three-phase full-bridge circuit is limited by the blocking voltage of the IGBT device and cannot directly output high voltage. As a result, in large-capacity applications, multiple three-phase full-bridge circuits need to be connected in parallel on the low-voltage side, so that the low-voltage bus current is very large

Although the capacity of the injection hybrid active power filter is improved, there are also disadvantages. Although the parallel connection of the active filter and the passive filter increases the harmonic filter capability, it is easy to make the active Filter resonates with passive filter

Although the injection hybrid active filter proposes a frequency division detection method based on the nth harmonic dq coordinate system, this method mainly uses low-pass filtering for filtering. The harmonics filtered by the low-pass filter account for the main component, and the phase The delay is difficult to compensate well, and the real-time performance of detection is mediocre; at the same time, although some injection hybrid filters have also been designed to use methods such as neural networks for harmonic frequency division control, since the detected harmonics have been synthesized into compensation signals, This is to carry out frequency division control, which not only increases the amount of calculation, but also has the problem of mutual interference

Images