Method for decomposing and reconstructing current instantaneous sequence component of triangular connection current transformer

Abstract

The invention discloses a method for decomposing and reconstructing a current instantaneous sequence component of a triangular connection current transformer. The method comprises the steps that S1, an instantaneous sequence component decomposition algorithm model is built, and the positive sequence component and the negative sequence component of a fundamental wave and the positive sequence components and the negative sequence components of all subharmonic waves are made to be completely decoupled and decomposed under a synchronous coordinate system; S2, the component correlation coefficients am<(1)> and am<(2)> of the m subharmonic waves is obtained; S3, the compensating current reference values of all triangular link current controllers are reconstructed to obtain the reference currents of all triangular links, and the reference currents are used for current tracking and control of the triangular current transformer. The method has the advantages that the positive sequence component and the negative sequence component of the current of the fundamental wave and the positive sequence components and the negative sequence components of the currents of all the subharmonic waves can be effectively extracted, and load currents and all triangular link currents can be decomposed and reconstructed accurately and fast. The accurate compensating current reference values are provided for the triangular connection current transformer, the number of times of harmonic compensation can be selected flexibly, and the defects that a traditional sequence decomposition algorithm is large in calculated amount and only fundamental components are considered are overcome.

Description

technical field [0001] The invention belongs to the technical field of three-phase current conversion in power systems, and relates to a method for current decomposition and reconstruction of a converter, in particular to a current fundamental wave and positive sequence components and negative components of each harmonic used for a delta-connected converter. Algorithms for instantaneous decomposition and reconstruction of ordinal components. Background technique [0002] In the power system, current imbalance and distortion are unavoidable when power electronic converters are running. Especially in the occasions where active filters, wind power and photovoltaic converters are involved in the operation, three-phase current imbalance is more common. It is usually necessary to use a three-phase converter to compensate the asymmetry and distortion of the three-phase current. In particular, in medium-voltage and large-capacity applications, since the three-phase three-wire syst...

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Problems solved by technology

[0005] In order to solve the shortcomings of the existing delta-connected converter positive and negative sequence component separation algorithm, the calculation process is complicated and the calculation amount is large, and a delta-connected converter current instantaneous sequence component decomposition and reconstruction method is proposed.

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