New controlled switching tech from Manitoba Hydro
Manitoba Hydro has developed an improved controlled switching technology to help energise large transformers.
Residual magnetic fields found in large transformers can make energizing them a tricky business. The resulting voltage depressions and harmonics can lead to flickering lights, equipment damage and even widespread outages for customers.
Special circuit breakers with pre-insertion resistors can reduce the problem, but don’t eliminate it. They are also expensive, getting hard to replace at 230 kV and below, and require frequent maintenance.
To solve this issue and to reduce costs, Manitoba Hydro investigated the application of controlled switching (also known as Point-on-Wave (POW) switching)— a relatively new technology that can safely energize large power transformers using standard circuit breakers.
Manitoba Hydro applied state of the art transformer modelling techniques and learned that the standard approach of using capacitor voltage transformers for measuring remnant flux inside the transformer was not accurate enough.
These modelling techniques and study approaches were enhanced for the case of parallel HVDC converter transformers. This allowed two HVDC converter transformers connected in parallel to be safely energized using controlled switching — a world first!
Source: Canadian Electricity Association
Photo (for illustrative purposes): Grey and Black Power Transmission Station / Pixabay / Pexels / Free to use