City’s solution to load-shedding

Johannesburg – City Power has explained how its technology helped keep the lights on last week, when Eskom clients suffered load shedding.

  The technology, which is functional in some parts of the city, allows remotely switching off items like geysers to save electricity, according to City Power spokesperson Isaac Mangena.

  He explained that load-limiting is only possible with households which have smart meters. “Of the 390 000 City Power customers, less than half of them have smart meters, which allow for individual households consuming too much power to be temporarily switched off. “About 150 000 smart meters were rolled out. Some of them are offline due to maintenance and load-limiting on them is not working,” he said.

  City Power gets about 90% of its electricity from Eskom, and 10% from the Kelvin Power Station, east of Joburg.

  “The extra capacity that City Power has comes from ripple relays control, which gives us up to 100MW. We have added 40 000 new ripple relays to households to aid in the remote switching off of geysers in peak hours,” Mangena said.

  He explained that load-limiting through the use of smart meters can give City Power up to 70MW of electricity. “For load-limiting to occur, Eskom notifies City Power of the megawatt contribution needed to keep the lights on. City Power then sends SMS notifications to its customers, as well as a message to the smart power unit indicating the number of megawatts needed from that particular household. If the house is consuming less power than the threshold, the the electricity remains on; but if the power consumed is above the limit, the smart meter disconnects the power supply to the house.”

He added that the meter will not switch power back until the amount of load required is acceptable, so the household will need to switch off non-essential items to be switched back on.

  “In the future successful implementation of load-limiting should yield 153MW over 65,037 smart meters. The long-term interventions using this will yield 775MW using 330 000 meters,” Mangena said.

  He added that through this initiative, the Kelvin Power station was able to contribute between 80MW and 200MW to the national grid. “Based on the current initiative, City Power can contribute 521MW to keep the Joburg lights on. If City Power can reduce the use of electricity via load-limiting, fewer areas will need load-shedding.”