She takes online fingerprints of power components

News

Publicerad 2013-11-04

Researchers don’t like them, nor do power companies. They are seen as disturbances in the power grid. But lightning and other natural high voltage currents are inevitable. Roya Nikjoo has exploited this fact to enable online diagnoses of power transformers. The innovative method landed her the international “Young Researcher Award” in high voltage engineering.

Roya Nikjoo, PhD student in SweGRIDS is taking advantage of natural high voltage currents to enable online diagnostics of power components.

High voltage current from lightning and power switches, so called natural transients, on the transmission line have the power to destroy components along the line. Researchers and power companies want to find ways to protect the grid from them. Roya Nikjoo, PhD student at the Swedish Centre for Smart Grids and Energy Storage, SweGRIDS see them as an asset.

“As we cannot do anything about these natural disturbances, I wanted to find a way to take advantage of them to get the fingerprints of the power components.”

In her research Nikjoo uses the high voltage from natural transients to do online diagnostics to find the overall wear and tear of the power components in transmission system, such as power transformers and bushings, connecting the transformer to the power lines in a power grid.

The signals created by lightning and power switches, as they open and close to break an electrical circuit, interrupting the current or diverting it from one conductor to another, are used as stimuli to obtain the response from power components.

Power components in the lab are provided with sensors that measure the current of lightning or switching devices on different frequencies as it goes through the component. With the output current produced by the input high voltage from the natural transient, she gets a response graph from the system much like when injecting a small current to measure muscle mass at the gym or taking an ultrasound of a fetus.

“It’s like getting the fingerprint of the component, as the fingerprints changes I can use it to identify the well-being of the component and know if something is wrong.”

The benefits are many. For the wide range of frequencies used in high voltage electric power transmission, maintenance can currently only be performed offline every 10 years or so.

“In this case I don’t need to shut down the system and induce external signals to get the fingerprints of the components. I can do the diagnostics online, at any time.”

“With this method we can get fingerprints several times a year. We can also follow the trends of the well-being of power components in a more systematic way.”

Power components such as transformers are also very expensive and take up to two years to build. If you know in advance, you can plan for the maintenance and construction of new components.

“Consequently, you will also avoid component failure that eventually could lead to blackouts.”

Natural transients have never been used before for insulation diagnostics. Nikjoo’s ingenious solution landed her the ‘’Young Researcher Award’’ at 18th International Symposium on High Voltage Engineering, ISH, 2013, Seoul, Korea this fall and a similar award in Vienna earlier this year for a paper entitled “'Insulation Condition Diagnostics of Oil-impregnated Paper by Utilizing Power System Transients”.

As far as Nikjoo’s test indicates, the method gives information about the components in a wide range of frequencies. Now she is in pursuit of greater accuracy for all the parameters.

“This is a really great leap forward in getting the fingerprints of the power components online. The next step is to take it from the lab and install it in the grid.”

For more information, contact Roya Nikjoo royasn@kth.se , +46 (0) 790 7765.

Text and photo: Marie Androv