A sudden loss of electricity generation may cause power shortage in the grid. The situation is very rare, but also very serious – to avoid a system collapse, the grid operator must quickly reduce the load on the grid. Today, the strategy is to disconnect the power supply at one or more substations, with the result that all the customers supplied via the substation are cut off, even public facilities such as health centres and pharmacies.
But the smart meters frequently installed by many power companies can offer a better strategy. Many smart meters are equipped with a switch that allows the power company to turn on and off electricity without visiting the property. Today, the function is mainly used to turn on and off electricity when customers move or to turn off the electricity for customers who have defaulted on their payments.
The switching functionality could also be used to disconnect a large number of individual clients at emergency situations in the grid. Priority customers, such as pharmacies and health centres, could be exempted from the emergency disconnections.
"Thus societal service could be retained", says Yasir Arafat, who is a PhD student in electric power engineering at Chalmers.
Moreover, the smart meters could offer faster reconnection of disconnected customers once the power shortage is over.
In three field studies Yasir Arafat used smart meters to disconnect nearly 200 electricity customers in quick succession and evaluated how the power quality in the area was affected as well as the performance of the smart meters. Power quality was affected very little – some brief voltage increases were noted, however, too small to harm even sensitive devices connected to the electricity grid.
"That was a good result. However, the existing smart meters also showed some limitations", says Yasir Arafat.
The limitations were largely in communication. The switching went a bit too slow and it also took a long time to rebuild communication with the smart meters after they had been disconnected. However, the concept of using smart meter switching for emergency grid management still looks promising.
On Thursday 27 August Yasir Arafat presents his research during a licentiate seminar. He will continue his doctoral project by performing simulations of the disconnection of a much larger number of electricity customers, built on data from the field studies.
"The goal is to find an optimal solution for smart meter emergency grid managment", says Yasir Arafat.
The research project is conducted in cooperation with Göteborg Energi.
Text: Ingela Roos