Controlled Switching of a 1200 MVA Transformer in Manitoba

This paper describes the application of a controlled switching device to energize a 500 kV/230 kV/46 kV, 1200 MVA autotransformer in Manitoba. The development of a detailed electromagnetic-transient (EMT) simulation model of the transformer formed the basis of the work described. The transformer model includes an accurate representation of hysteresis and remanance, which was validated using recorded waveforms and manufacturer data. This paper discusses a feasibility study conducted using this transformer model to evaluate the suitability of controlled switching to energize this transformer. A series of real-time hardware in the loop tests was conducted using a real-time simulator as part of precommissioning tests. The real-time simulation (RTS) tests and phase 1 of commissioning tests conducted in October 2014 showed that the controlled switching device would produce inaccurate residual flux estimates when it integrates the secondary voltage waveforms of a capacitive voltage transformer. Based on these RTS test results and EMT simulations, the installation of a wound potential transformer (PT) was recommended. This paper also discusses simulation studies conducted to manually program the controller until the PT was commissioned. During phase 2 of testing conducted in October 2015, a wound PT was commissioned and the controller was tested. The recorded waveforms showed good agreement with simulation results. The controller has accurately predicted residual flux and minimized inrush currents during transformer switching events.