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JWG A2/C4.52 High-frequency transformer and reactor models for network studies

Context

A recent JWG A2/C4.39 "Electrical transient interaction between transformers and the system" has completed its work. The JWG performed a review of the overvoltages that a transformer can be subjected to in service, focusing on shape of impinging overvoltages and pertinent modeling techniques. The JWG brochure includes the following findings: • A transformer subjected to a voltage transient waveform with an oscillating component and /or a very high rate of rise may suffer dielectric failure due internal resonances or unpredictable withstand of the insulation to very fast transients.

• The manufacturer's white-box models are able to predict the maximum overvoltage stresses due to standard test voltages with fairly good accuracy. However, the accuracy deteriorates when the model is subjected to oscillating overvoltages and/or aperiodic impulses with a very high rate of rise.

• Black-box models based on measurements can accurately predict the transformer terminal behaviour also during resonant conditions up to a certain frequency range, but they do not provide information about the internal overvoltages. The manufacturers do not in general supply the customer with a model of the transformer, neither a black-box model nor a white-box model. This prevents the customer from including the transformer in network studies. In this context, the focus of the proposed JWG is to continue the work of A2/C4.39 in the direction of transformer modeling with the objective of providing the customers with useful models of the transformer for application in system transient studies.

Scope and Aim

• Provide guidelines and recommendations for the generation of transformer models for simulation of high-frequency transient overvoltages that can occur in actual service.

• Define minimum requirements that models supplied by manufacturers to customers must comply with for including the transformer model in network studies.

Convener:B. Gustavsen (NO)

 

Progress Report 2014 (pptx, 199kB)

Progress Report 2015 (pptx, 132kB)

Progress Report 2016 (pptx, 97kB)

http://a2.cigre.org/WG-Area/JWG-A2-C4.52-High-frequency-transformer-models-for-non-standard-waveforms