Calculation method for lightning impulse winding overvoltage of phase-shifting transformer

Abstract

The invention provides a phase-shifting transformer lightning impulse winding overvoltage calculation method, which comprises the steps of (1) generating an equivalent wiring schematic diagram of a phase-shifting transformer according to a wiring mode of the phase-shifting transformer; (2), establishing a preliminary equivalent circuit model of each winding of the phase-shifting transformer; (3) calculating each capacitance and inductance value in the preliminary equivalent circuit model; (4), determining a final equivalent circuit model of the phase-shifting transformer; (5) applying lightning waves with corresponding amplitudes to related positions in the final equivalent circuit model; and (6) solving the circuit model by using circuit simulation analysis software to obtain a change curve of the voltage of each part of the winding in the phase-shifting transformer along with time and voltage distribution conditions in the winding at different moments. According to the method, the insulation strength of the high-voltage winding of the phase-shifting transformer between line cakes under the lightning impulse voltage can be rapidly and accurately calculated, the insulation strengthof the phase-shifting transformer can be well analyzed by utilizing the calculation result, the manufacturing design of the insulation structure of the phase-shifting transformer is guided, and the detection test level is improved.

Description

Technical field [0001] The invention relates to the technical field of transformer anti-lightning impulse, in particular to a method for calculating overvoltage of a phase-shifting transformer lightning impulse winding. Background technique [0002] The Phase Shifting Transformer (PST) adjusts the phase angle to realize the power flow distribution in the transmission network, which makes the distribution of electric energy more reasonable, and improves the operational stability and efficiency of the power system. Compared with traditional transformers, phase-shifting transformers have complex structures, especially double-core structures. When designing product insulation structures, it is necessary to focus on the influence of various voltages such as power frequency voltage, lightning overvoltage, and operating overvoltage. A certain margin ensures the safety and reliability of the insulation structure of the product. The equivalent frequency of the lightning impulse voltage w...

AI Technical Summary

Problems solved by technology

Lightning shocks intruding into the transformer will generate a complex electromagnetic process in the transformer winding, that is, the winding wave process, resulting in uneven voltage distribution between winding turns, wire cakes, and between windings and between windings and ground components. The difference between the voltage distribution and the final voltage distribution will generate an oscillating voltage, once the dielectric strength of the insulating medium is exceeded, it will cause insulation damage failure

Therefore, both conventional transformers and phase-shifting transformers need to be tested for lightning impulse during manufacture, and there is no national standard for lightning impulse testing of phase-shifting transformers. An important prerequisite for compiling the test plan is to understand the potential and electric field distribution of the phase-shifting transformer under the lightning impulse voltage during operation, and to know the influence of the application method and amplitude of the lightning impulse on the potential and electric field distribution during the test, so as to clarify the corresponding The requirements and conditions for the design and assessment of the insulation structure of phase-shifting transformers, therefore, the calculation of the voltage distribution of phase-shifting transformers in the lightning impulse winding is of great significance to the design of products and test programs

[0003] At present, the calculation methods for the lightning impulse winding overvoltage of the transformer mainly include the finite element method model calculation method and the distributed parameter model calculation method. Since the series transformer and the excitation transformer of the double-core phase-shifting transformer need to be connected with a large number of connecting parts, If the finite element method model is used to directly and accurately calculate the lightning impulse voltage distribution in the winding and the impulse voltage transfer process between the windings, the process is complex, the amount of calculation is large, and it is very time-consuming, so it is very difficult; if the distributed parameter model calculation method is used, due to the phase shift There are great differences in the structure of transformers and ordinary transformers, which makes the calculation complex and lacks experimental verification methods. Therefore, there is no reliable and unanimously recognized method in the industry to use the distributed parameter model calculation method for phase-shifting transformers.

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