Analysis Of Lightning Impulse Response Of Dry-type Transformer

When the power transformer is in the operational process, it will be effected by various impulse over-voltage. Among them, the lightning impulse has the greatest impact for the insulation structure of power transformer. Seriously, it will lead damage to transformer, causing power outage. Currently, the research on lightning impulse response of dry-type transformer is not inadequate. Especially in the lightning impulse response analysis software design of dry-type transformer is very few. Therefore, the Research on the winding voltage distribution of dry-type transformer under lightning strike action has important practical significance.Through the research on the equivalent circuit model of dry type transformer, it proposed the establishment of the transformer generic equivalent circuit model based on the envelop number of dry-type transformer winding. And it develops the universal calculation software of dry type transformer lightning impulse response on the basis of equivalent circuit model.First of all, according to the current structure of dry-type transformer products, dry-type transformer is classified by envelop number and it establishes the equivalent circuit model of different types of dry-type transformers. This article makes dry-type transformer divide four cases by envelop number, such as one envelope, two envelopes, three envelopes and four envelopes, establishing the equivalent circuit model.Secondly, the paper analyzes the calculation method for winding inductance, capacitance and resistance parameters of transformer. The matrix differential equations of equivalent circuit are suitable for application Matlab language programming, simplifying the method of calculating the lightning impulse response of dry-type transformer. The author uses Ansoft software to calculate the electric field distribution of winding insulation structure in the frequency and lightning impact. Meanwhile, the study analyzed the electric field distribution of insulation material shortage regions in the lightning impact effect. The results show its electric field distorts seriously, which threats to the safe operation of dry-type transformer.Then, it designs the lightning impulse response calculation software of dry-type transformer, which has good man-machine interactive interface. In the software development process, it makes full use advantages of VB and Matlab language. It uses the hybrid programming ideas to write VB parameter input interface and Matlab equivalent circuit calculation program. The software is compared with the similar software, having friendly input interface, high calculation precision and wide range of advantages. Meanwhile, the software has an error prompt and helpful information, greatly reducing the users’difficult to master the software.Finally, in order to prevent users from repeatedly input parameter data, it uses Access2007database to design the software database. Users can query and modify the files through the database, providing with great convenience. The results of the paper provide reference basis for the initial design phase of dry-type transformer, and the development of the software has a strong practical value.