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.

This paper describes Manitoba Hydro's over 20 years of experience with monitoring, investigating, and mitigating GIC effects in the high voltage transmission network. A summary of GIC events captured using the EPRI SUNBURST monitoring system is presented. This includes the peak season of solar cycle 23 and the ongoing solar cycle 24. Several strategies adopted for mitigating GIC effects and a summary of research & development initiatives sponsored by Manitoba Hydro are also discussed.

This paper investigates application of a protection scheme to mitigate the impact of temporary overvoltages caused by load rejection in the Manitoba Hydro 500 kV transmission system. The sectionalization of Dorsey - Forbes 500 kV line at Riel affects temporary overvoltages seen during a load rejection. The results of electromagnetic transient simulations show that overvoltages due to a load rejection on 230 kV side could severely stress surge arresters and other equipment at both Dorsey and Riel stations, and could also lead to ferroresonance. The simulation results formed the basis for functional specification of the new protection scheme at Riel station.

This paper describes several system configurations that could lead to very high breaker transient recovery voltage (TRV) and rate of rise of recovery voltage (RRRV) in the presence of phase-shifting transformers, synchronous condensers, and switched capacitor banks. The special considerations involved in determining the most limiting TRV and RRRV are presented. Mitigation measures required for 15kV and 115kV breakers that are applied in the above system configurations are also presented. Simulation results presented are part of a design study carried out for the proposed extension to Granite Station in Vermont.

This paper presents a simulation algorithm to simulate the hysteresis characteristics in the core of a power transformer. The algorithm is based on the Jiles–Atherton phenomenological model of a ferromagnetic material. The new transformer model is capable of producing a close representation of the transformer magnetizing current. Comparisons are made between recorded and simulated waveforms using a single phase distribution transformer. A good agreement is achieved between recorded and simulated data.

A hysteresis model based on the Jiles-Atherton theory is incorporated into a power transformer model in an electromagnetic transient program (EMTP)-type program. The eddy current effects are also included in the same model. Comparisons are made between recorded and simulated waveforms using a single-phase distribution transformer. A good agreement is achieved between recorded and simulated data.

This work describes the simulation of the effects of GIC (Geomagnetically Induced Currents) in a power system using a new transformer model. The simulation studies demonstrate that it is important to accurately model the remanence effects in the core of the power transformer.

This paper describes the development of an electromagnetic transient model to represent the eddy current effects in transformer magnetising current. The magnetising current of a transformer is both nonlinear and frequency dependent. The frequency dependence is due to eddy currents. The most commonly used method to represent losses in a transformer model is to add a shunt resistance across one winding. In this paper we have extended a hysteresis model based on the Jiles Atherton theory of ferromagnetic hysteresis to include the effects of eddy currents. A comparison of simulation results and test results is presented in the paper.

This paper describes the development of a mathematical model of three current transformers which are connected in a delta configuration as part of a differential protection scheme. The delta connected configuration is typically found in transformer differential protection schemes for star - delta transformers. This model can be used in real time algorithms for testing of relays and can also be used to study differential protection schemes off-line. The accuracy of the model is validated by comparing the simulations with waveforms recorded at a synthetic test plant.

This paper presents the simulation of multiple current transformers (CTs) operating in parallel into a common spill circuit. The voltage across the spill branch in the high impedance case can be quite high and a varistor (MOV) may be placed across the spill branch to keep this voltage within safe limits.

This paper describes the development of a mathematical model of an air gapped current transformer. Air gapped current transformers are widely used in generator protection since these have the capability to overcome some of the problems encountered when using conventional current transformers. The model developed here is validated by comparing simulation results with recorded waveforms from a manufacturers synthetic test plant.