CVT power frequency simulation model and simulation method for intermediate transformer under overexcitation working condition

Abstract

The invention discloses a CVT power frequency simulation model and simulation method for an intermediate transformer under an overexcitation condition. The model comprises a capacitance voltage division unit, a compensation reactor, the intermediate transformer and a ferromagnetic resonance suppression unit. According to the CVT power frequency simulation model and simulation method under the over-excitation working condition of the intermediate transformer, a CVT intermediate transformer model with physical significance is constructed according to the electromagnetic dual principle, and model parameters comprise primary side and secondary side winding resistors R's1 and Rs2, leakage reactance L's, nonlinear excitation reactance L'm1 and Lm2 of two excitation branches and parallel resistors R'm1 and Rm2. The model is provided with two excitation branches which are in one-to-one correspondence with the whole CVT structure, and accurate simulation of saturation difference of the intermediate transformer iron core under an over-excitation working condition can be realized.

Description

technical field [0001] The invention belongs to the field of electric power technology, and particularly relates to a CVT power frequency simulation model and a simulation method under the overexcitation condition of an intermediate transformer. Background technique [0002] As an important primary equipment in the power system, CVT (Capacitance type voltage transformer, capacitive voltage transformer) has complex structure and response characteristics. In the case of power frequency, the CVT relies on the series resonance of the compensation reactor and the capacitive voltage divider to improve the accuracy and load capacity, and the low-voltage side output and the high-voltage side input satisfy a linear relationship. like figure 1 As shown, the CVT power frequency simulation model provided for the prior art. [0003] However, there are compensation reactors, intermediate transformers and ferroresonance suppression units due to the non-linear components in the CVT. Usua...

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Problems solved by technology

Usually, the compensation reactor can be treated as a linear reactance at 4 times the rated voltage; and because the magnetic flux of the iron core is proportional to the voltage and inversely proportional to the frequency, when the system occurs subsynchronous oscillation or ferromagnetic resonance, it may cause The overexcitation condition occurs, and the iron core of the excitation intermediate transformer is saturated. At this time, the original resonance condition of the CVT is broken, and the output voltage of the secondary side cannot follow the input voltage change of the primary side.

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