Method for calculating DC (direct current) magnetic bias dynamic leakage inductance of transformer

Abstract

The invention relates to a method for calculating DC (direct current) magnetic bias dynamic leakage inductance of a transformer. The method is characterized in that: the method comprises a dynamic parameter calculation step based on a transient field-circuit coupling model, and a dynamic leakage inductance calculation step based on transient field-circuit coupling; the method can establish a three-dimensional finite element magnetic field model of the transformer and solve the model to fully reflect the accuracy of magnetic field calculation under nonlinear excitation of the transformer; and the method can calculate dynamic inductance parameters according to the energy perturbation principle, calculate a transient current by combining with four-order Range-Kuttle method, and then calculate the dynamic leakage inductance based on a T-shaped equivalent circuit of the transformer. In comparison with the existing harmonic calculation method, the method provided by the invention can calculate the dynamic leakage inductance by considering the transient changes of equivalent parameters of magnetic field and circuit of the transformer and the relationship between the parameters under different DC perturbations on the basis of field-circuit coupling. Accordingly, the method provided by the invention has higher adaptability, and higher actual application value.

Description

technical field [0001] The invention relates to a dynamic leakage inductance calculation method of transformer direct current bias, which is applied to transformer fault parameter calculation, stable operation analysis and novel protection setting. Background technique [0002] The operation status of the transformer directly affects the safety and stability of the power equipment and even the entire power grid. The protection scheme for transformers suffering from direct current in the environment of UHVDC single-pole system and geomagnetic induction current is not perfect. According to the survey, the transformer protection criterion based on the new protection principle is mainly based on the loop equation or the leakage inductance parameter. Among them, the transformer protection method based on inductance parameters is a new research field that has attracted much attention. Therefore, the calculation and analysis of the inductance parameters when the transformer is fau...

AI Technical Summary

Problems solved by technology

[0003] The traditional method uses the "T" equivalent circuit of the transformer to calculate the leakage inductance parameters of the transformer. It is believed that the leakage inductance of the transformer remains unchanged when there is no internal fault. Because the excitation current is ignored, the calculation result has a large error; on the other hand, the static transformer is established according to the actual transformer. The magnetic field model cannot consider the changing characteristics of transient parameters during calculation, so the inductance parameters of the transformer cannot be accurately calculated

Images