Transformation matrix-based transformer three-phase model building method

Abstract

The invention discloses a transformation matrix-based transformer three-phase model building method. The method comprises the following steps of establishing an original admittance matrix Yp of a three-phase transformer, and according to primary and secondary side connection modes of the transformer, modifying a transformation ratio of the matrix Yp; according to the primary side connection mode,determining a primary side voltage transformation matrix Cp; according to a primary and secondary side wiring mode, determining Csp and Cps; according to mark numbers of groups, converting a basic secondary side voltage transformation matrix Css through a transformation matrix to obtain a secondary side voltage transformation matrix Cs and modifying Cps; according to sub-matrixes of the voltage transformation matrixes, forming a voltage transformation matrix C and a current transformation matrix G of the transformer; and according to the matrix Yp and the transformation matrix, deriving a nodeadmittance matrix YTn of the three-phase transformer. The method solves the problem that a relation matrix method is not suitable to obtain node admittance matrixes of transformers of certain connection groups, further reduces the software writing workload and the error probability, and improves the accuracy of obtaining a three-phase model of the three-phase transformer.

Description

technical field [0001] The invention relates to a method for establishing a three-phase model of a transformer, in particular to a method for establishing a three-phase model of a distribution three-phase transformer used in the calculation of the three-phase power flow of a distribution network. Background technique [0002] The power distribution system is a network system that directly distributes electric energy to end users, which is composed of distribution lines, distribution transformers, distribution voltage regulators, distribution switches, distribution capacitors and distribution loads. To conduct power system analysis, it is first necessary to establish a suitable model for each component in the system. Different from the three-phase symmetrical operation mode of the high-voltage transmission network, the load and network of the distribution network may be asymmetrical. When performing power flow calculations on the distribution network, the characteristics of t...

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Problems solved by technology

In order to design a perfect three-phase power flow calculation program for the distribution network, the programmer needs to manually derive the three-phase models of the transformers in these connection groups one by one, which is very inconvenient and difficult to guarantee the accuracy of the derived three-phase model of the transformer

Therefore, Chinese patent CN201610579878.4 proposes a method for automatically generating a three-phase model of a power distribution three-phase transformer, which can make full use of Matlab's unique characteristics of being good at matrix operations and complex operations, and use symbolic operations to automatically derive the nodal admittance of the three-phase transformer The matrix model solves the time-consuming and labor-intensive problem of manually deriving the three-phase model of the distribution three-phase transformer, and improves the efficiency of obtaining the three-phase model of the three-phase transformer

However, when this method derives the nodal admittance matrix model of the three-phase transformer, it uses many correlation matrices, which are relatively complex and prone to errors in programming, which still needs further optimization and simplification of the modeling process

In addition, the traditional correlation matrix method cannot directly deduce the nodal admittance matrix of the three-phase transformer whose primary and secondary windings are connected in a star-shaped neutral point.

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