Summary
In case of an electrical blackout, an available power plant can be used to energize a nearby nuclear power plant via an isolated network. To validate and operationalize these power restoration networks, blackout anticipation tests are periodically conducted. During one such test, an induced voltage of 160 kV was recorded, along with a sustained high voltage exceeding the regulatory operating limits for the tested 400 kV power system. The grid topologies under test are rarely encountered during normal operation of power systems but they may occur during or after a blackout. Therefore, better understand the phenomenon leading to this damaging sustained high voltage is fundamental for safe and reliable power system restoration.
Read more Read lessIn this article, electromagnetic transient (EMT) simulations are used to investigate the recorded sustained high voltage phenomenon. The EMT model was tuned with the field test measurements of the induced voltage and the energized isolated network. The tuning corroborates with existing literature on induced voltages in power systems; and demonstrates the model’s sensibility to the phase sequence arrangement of the lines in the double-circuit transmission towers. Due to this sensitivity to uncertain and variable parameters, the precise modelling of the coupling between networks is deemed unreliable without model tuning.
The sensitivity analysis conducted with the tuned model indicates that the observed overvoltage is a ferroresonant event caused by the saturation and the remanent flux of the autotransformers; and the difference between the two frequencies (restoration network and the grid) at the time of switching. The model reproducing the measured overvoltage is highly sensitive to parameter changes, with the results shifting among three distinct states. The simulation results were validated with onsite measurements.
Additional informations
| Publication type | Session Materials |
|---|---|
| Reference | C4_10907_2026 |
| Publication year | |
| Publisher | CIGRE |
| Country | France |
| Study committees |
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| File size | 1,007 KB |
| Price for non member | 30 € |
| Price for member | 30 € |
Authors
SANTOS DA SILVA Safire - EDF; CANAL Toussaint - EDF; RENOUARD Vincent - EDF; ZGAINSKI Francois-Xavier - EDF
Keywords
Blackout, Power System Restoration, Grid-to-Grid Coupling, Induced Voltage, Resonant Overvoltage, Ferroresonance, Switching Transients
