Hybrid active filter resonance suppression strategy considering control delay

Abstract

The invention relates to a hybrid active filter resonance suppression strategy considering control delay, which takes a hybrid active filter applied to high-voltage direct current transmission as a research object, and belongs to a novel resonance suppression method. However, a hybrid active filter is complex in impedance characteristic and easy to generate a resonance risk, in addition, due to calculation delay and sampling delay, the hybrid active filter may present a negative impedance characteristic, and the stability of an alternating-current and direct-current system is greatly impaired. Therefore, an impedance model is established, the influence of digital time delay on the system stability is analyzed, a self-adaptive resonance suppression strategy based on a minimum mean square algorithm is designed, the design thought of feed-forward compensation is adopted, the waveform of the next moment is predicted to eliminate phase lag caused by control time delay, not only the impedance characteristic of the filter can be improved, but also the prediction matrix can be adaptively adjusted, so that the invention can be applied to conditions of working conditions and circuit parameter changes.

Description

technical field [0001] The invention relates to a hybrid active filter resonance suppression strategy considering control delay, which belongs to the application fields of system stability and power electronic devices. Background technique [0002] As a means of suppressing harmonic pollution, hybrid active filters have attracted widespread attention due to their superior performance. The active filter based on the cascaded H-bridge type can realize the free expansion of the compensation capacity of the active filter under the limited device capacity, and can be applied to high-voltage direct current transmission projects. However, from the AC side, the active filter can be considered as a voltage source with complex internal resistance characteristics, and the reactive power compensation capacitor is connected to the bus of the converter station, so the impedance characteristics at the coupling point of the AC bus are complex, It is easy to generate the risk of resonance, ...

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Problems solved by technology

However, from the AC side, the active filter can be considered as a voltage source with complex internal resistance characteristics, and the reactive power compensation capacitor is connected to the bus of the converter station, so the impedance characteristics at the coupling point of the AC bus are complex, It is easy to generate resonance risk, which greatly endangers the stability of AC system and DC system

At present, there are many ways to suppress the resonance caused by power electronic devices in the system, such as increasing the system damping, changing the resonance point, impedance transformation, etc., but less consideration is given to the hybrid active filter and system resonance caused by the control delay , in fact, the control of the active filter has high requirements on real-time performance. Due to the existence of the dead zone effect of the controllable device and the digital control of the system, the control delay cannot be ignored

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