A simulation calculation method and device for excitation current during DC bias

Abstract

The invention provides an exciting current emulation calculating method at the time of direct-current magnetic biasing. The calculating method comprises the steps of: constructing an electric network model according to a target electric network; building a transformer magnetizing current curve according to the transformer no-load excitation characteristic curve; setting direct-current magnetic biasing exciting current I0, and revising the transformer magnetizing current curve; after setting other node and shunt parameters of the electric network, carrying out emulation operation; and obtaining steady-state exciting current according to the emulation data, calculating the direct-current component I'0, revising the transformer magnetizing current curve again until I'0=I0, when I'0=I0, comparing I2 and KxbI1, and carrying out inrush current locking operation when |I2| is larger than kxb * |I1|. According to the invention, emulation calculation can be rapidly carried out on the transformer exciting current at the time of set direct-current magnetic biasing, the harmonic wave characteristics of the transformer exciting current can be effectively identified, and the influence of the exciting current at the time of direct-current magnetic biasing on the transformer protection is analyzed, thus the phenomenon that the protection element fails to operate or has unwanted operation is prevented and favorable influence is brought for the power transmission and transformation system.

Description

technical field [0001] The invention belongs to the field of power transmission and transformation, and in particular relates to a simulation calculation method and a device for excitation current during DC bias. Background technique [0002] When the DC bias interference is mixed with the sinusoidal power frequency excitation at the end of the transformer winding, the operating condition of the transformer is called DC bias magnetic condition or DC bias condition. For the principle of transformer DC bias, please refer to the appendix figure 1 . In the case of AC overexcitation of the transformer, the magnetic flux density of the iron core increases, and the excitation current is distorted. The transformer works in the non-linear region of the magnetization curve, the excitation current waveform is a peak wave, and the positive and negative half waves are symmetrical, see the attached figure 1 Excitation current curve is shown. Under the DC bias of the transformer, the D...

AI Technical Summary

Problems solved by technology

[0005] Regardless of the series-parallel connection mode, it is necessary to establish an AC and DC hybrid connection model in the grid model, which is technically complex

Some professional mathematical simulation software does not even have a magnetic field model. Even if a power grid model with AC and DC hybrid connections is established, it cannot accurately simulate the transformer flux characteristics under DC bias

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