Time-reversal method that could make power transformers more reliable
Engineers at EPFL have developed a revolutionary method for detecting and locating partial discharges, which disrupt the functioning of power transformers.
Image source: EPFL
Switzerland, Lausanne: Engineers at EPFL’s Electromagnetic Compatibility Laboratory have developed a revolutionary method for detecting and locating partial discharges, which disrupt the functioning of power transformers.
Transformers play a central role in power distribution systems, making it possible to carry electric power over long distances with minimal risk and losses. They are crucial for ensuring the stability and reliability of power grids. When problems occur in transformers, grid operators need to be able to detect them rapidly and determine exactly where they are located. “Sometimes, disturbances known as partial discharges occur inside a transformer,” says Farhad Rachidi, adjunct professor at EPFL and head of the Electromagnetic Compatibility (EMC) Laboratory. “If operators don’t do anything to fix them, the discharges can result in serious damage over time and even cause the transformer to explode.”
There are a selection of techniques that may detect partial discharges, however they are not very efficient in pinpointing the place they originate. “With our methodology, engineers can find the supply of a partial discharge and act rapidly to resolve the issue,” says Hamid Reza Karami, scientist on the EPFL EMC Lab. “It is based on a fairly recent technique called time reversal, which stems from the ‘reversibility’ of physics equations. Just about all physics equations have a time variable and consider it as a value going forward. But most equations also work with its negative. So, our technique entails replacing the t variable in physics equations, which represents time, with its negative: –t. Theoretically, that allows us to go back in time.”
Partial discharges inside a transformer generate two sorts of waves: acoustic and electromagnetic. Within the EPFL system, the waves are captured by a sensor and transformed into digital format. An algorithm then analyses the waves and feeds them into a pc mannequin of a transformer. The mannequin reconstructs the waves by working backwards, in the wrong way of journey, until it reaches the supply of the discharge. That provides engineers exact data on the place the discharge comes from.
Rachidi’s team is developing their technology jointly with Sparks Devices, a Fribourg-based firm that provides techniques for detecting partial discharges, and with HEIG-VD.
Time-reversal-based strategies have significant potential in a number of purposes—and this is not the primary breakthrough by Rachidi and the engineers at his lab. In 2018, they patented an application that may locate short circuits in power grids in record time.
Source: EPFL
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