HVDC (high voltage direct current transmission) direct current active power filter repetitive control method based on system identification

Abstract

The invention discloses an HVDC (high voltage direct current transmission) direct current active power filter repetitive control method based on system identification. The HVDC direct current active power filter repetitive control method specifically includes: step 1, drawing an equivalent circuit diagram of a topological structure of the HVDC direct current active power filter based on the system identification; step 2, setting up a transfer function for confirming control objects according to control targets which are harmonic current and filtering branch circuit impedance both enabling offset current of a filtering branch circuit to be equal to negative; step 3, assuming control object models according to a system identification based repetitive control theory; step 4, performing system identification based repetitive control on the controlled objects; and step 5, performing cascading PI processing on the controlled objects after being subjected to the system identification based repetitive control. Adverse influence on controlled system performance caused by uncertainty and time-dependent nature of parameters of the controlled objects is overcome, filtering frequency bandwidth has good inhibitory effect on each harmonic wave, controllers are simple in structure, DSP(digital signal processor) implementation is facilitated, and the HVDC direct current active power filter repetitive control method has high response speed and small steady-state errors on the premise of guaranteeing stability.

Description

technical field [0001] The invention relates to a repetitive control method of an HVDC direct current active filter, in particular to a repetitive control method of an HVDC direct current active filter based on system identification. Background technique [0002] The HVDC power transmission system will generate a large number of harmonics on the DC side, causing interference to adjacent communication lines, affecting communication quality, and even endangering the safety of communication equipment. With the development of power electronics technology and digital signal processor (DSP) With the improvement of performance, the active power filter (APF) is gradually applied to the filtering of HVDC transmission system. Compared with the traditional passive filter (passive filter, PF), the active power filter is not affected by the grid impedance, can dynamically suppress the harmonics in the system, and has the advantages of less land occupation, high efficiency and low cost ,...

AI Technical Summary

Problems solved by technology

[0003] The control method determines the performance of the active filter to a large extent; the current HVDC DC active filter control method mainly uses comb filters or notch filters as the control Closed-loop control of the device; control based on the principle of interference cancellation; high-gain feedback control, these control methods have more or less small stability margins, poor robustness, complex structures, and good cancellation effects only for specific orders of harmonics In addition, due to the need to detect line harmonic current as a feedback signal, when the harmonic current in the line is small, the feedback signal is easily affected by system noise

The composite control based on the approximate inverse system method respectively detects the harmonic current of the converter and the output current of the active filter as the reference signal and the feedback signal, which improves the anti-interference performance and has better control performance than the aforementioned control method. The control object of the feedforward controller is complex in the design of an approximate inverse system

Adaptive control obtains the real-time estimation of the parameters of the control object through online identification of the control object, and adjusts the controller parameters in time to give an appropriate control amount, which overcomes the uncertainty of the control object model in the above control methods and The problems caused by the time-varying nature of the control object parameters, but the calculation is large and the controller design is complex

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