Can lightning strikes protect smart grid components?
“We can use these high voltages to obtain more information about the condition of components like transformers and bushings than through offline inspections,” explained Roya Nikjoo of the KTH Royal Instititute of Technology . “It gives us a more systematic way of tracking the trends in how components’ conditions are affected by high voltages.”
The technique Nikjoo developed can be thought of as ‘preventive medicine’ because it enables a method to replace or fix components before they cause damage to neighbouring equipment.
The work has earned Nikjoo honors from SweGRIDS, as well as the Young Researcher Award at the 18th International Symposium on High Voltage Engineering, ISH, 2013, Seoul, Korea, for her paper entitled ‘Insulation Condition Diagnostics of Oil-impregnated Paper by Utilizing Power System Transients’. Nikjoo won a similar award in Vienna in 2012.
The measurements begin as the signals created when lightning or power switches break an electrical circuit, interrupting the current or diverting it from one conductor to another. Those signals are used as stimuli to obtain the response from power components.
Starting her project in 2011, Nikjoo equipped power components in the lab with sensors to measure the current of lightning or switching impulses with different frequencies as it goes through the component.
The output produces a graphic representation of the system, much the same way as ultrasound produces an image of a fetus. “It is like getting the fingerprint of the component,” said Nikjoo. “As that fingerprint changes I can use it to identify the well-being of the component, and know if something is wrong.”
In recent months Nikjoo has been performing the tests with higher voltages that are more akin to what occurs in the field. She also has been investigating all the parameters that can affect the accuracy of the results, such as the cables’ coupling, in the measurement circuit.
The method will save power grid operators money in equipment replacements and maintenance, while keeping customers powered up.
“This can make electricity more reliable in a smart grid. Customers won’t need to worry about blackouts or losing money due to a shutdown,” suggested Nikjoo.
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