SOGI-based single-phase transformer short-circuit parameter on-line real-time identification method

Abstract

The invention discloses an SOGI-based single-phase transformer short-circuit parameter on-line real-time identification method. The identification method comprises steps of establishing a T-type equivalent circuit of a single-phase transformer; listing the short-circuit impedance parameter equation and the T-type equivalent circuit equation of the transformer; respectively obtaining the d axis equation and the q axis equation of the T-type equivalent circuit in a dq coordinate system; and using a SOGI-FLL model to extract fundamental wave components and fundamental wave orthogonal components of all input signals, obtaining the d axis component and the q axis component of all input signals in the dq coordinate system, and calculating the short-circuit resistance values Rk and Xk of the single-phase transformer, thereby achieving on-line monitoring of operation states of single-phase transformer windings. When windings of the transformer deforms and break down, the short-circuit impedance of the transformer will change. By measuring voltage and current of the primary side and the secondary side of the transformer, short-circuit parameters of the transformer windings can be identified. Thus, on-line monitoring of the operation states of the transformer windings is achieved; potential risks of the transformer can be found as soon as possible; fault points can be timely removed; operation accidents can be avoided; and service lifetime of the transformer is extended.

Description

technical field [0001] The invention relates to an online identification method for a unidirectional transformer, in particular to an online real-time identification method for a single-phase transformer short-circuit parameter based on SOGI. Background technique [0002] The transformer is a very important electrical equipment in the power system, and its safe operation is directly related to the power supply reliability of the power system. In the process of transformer operation, various forms of faults will inevitably occur. Among the many faults of transformers, winding faults have always occurred the largest number. Among the methods for diagnosing transformer windings, frequency response method, impedance analysis method, and low-voltage pulse method are available. They are desirable, but they are all off-line methods, which cannot detect transformer winding faults in time, and are not suitable for on-line measurement. [0003] Chinese Patent No. CN200810011051 discl...

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But when the input matrix |AA identified by the least squares method Τ When |=0, the parameters are not identifiable, causing the identification r...

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