Just in time for winter, Swiss researchers have developed a faster, more efficient way to pinpoint exactly where short circuits occur in a power grid. When a high-voltage power line is damaged, electrical utilities have to locate a fault so they can repair it and avoid a widespread power outage. Typically, they use sensors placed at regular intervals along the power line to find the section without power. Then a technician visually inspects the line to find the fault location. Researchers at the École polytechnique fédérale de Lausanne (EPFL) in Switzerland have developed a less labor-intensive method, based on the theory of electromagnetic time reversal.
An EPFL release explains: “With this method, researchers developed an embedded hardware platform hosting the fault location algorithm connected to the primary substation in the grid. When a short circuit occurs, the system analyzes the resulting waveforms observed at the measurement point. The fault location platform then time-reverses the waveforms and reinjects them into the grid model being simulated in the platform. The back-injected signals converge towards a given location which is the fault location.” This method has also been implemented in a chip-scale real-time simulator that the same team developed.
As long as power lines remain above ground, faults from wind, ice and tree damage are inevitable. This faster, more efficient way of locating short circuits will at least minimize power loss and make it easier for technicians to find and fix the lines. The researchers say that the method is especially ideal for large-scale, complex grids. Offshore wind farms, for example, usually use multi-terminal High Voltage Direct Current (HVDC) links, which extract and deliver power between several terminals and provide power to more than one terminal. Locating faults has especially been a challenge for these grids, but this new method would quickly locate them with just a single measurement point. “With a large number of reflecting boundaries and inhomogeneous transmission lines along which the waves are traveling and reflected, the result are even more precise than for a simple topology,” said an EPFL researcher.