Demand Response

What is Demand Response?

Demand Response (DR) is defined as a measurable change in electrical demand by customers or Load Providers in response to a curtailment notice.

Demand Response options available:

Instantaneous Demand Response Programme

Supplemental Demand Response Programme

Typical curtailment activities include:

  • Reducing electrical power to production equipment
  • Turning of air conditioning units.
  • Shutting off lights

All electricity consumers that qualify to participate on the Eskom DR programme are contracted with Eskom (via an agreement) on a yearly basis. These Load Providers contracted with Eskom on the programme receive:

  • A financial incentive based on actual performance and
  • Could potentially be excluded from national load curtailment/shedding stage 1 & 2

Background

The Eskom System Operator (SO) is responsible for the reliability and security of the South African national electricity grid by monitoring, controlling and operating it in a safe, economical and reliable manner.

The DR programme fulfils an important role towards power system security by providing the SO with much needed flexibility and reliability to maintain adequate daily operating reserve margins. The reserve margin caters for unforeseen circumstances that could affect the stability of the supply.  Factors that could affect the stability of the electricity supply include:

  • System constraints caused by severe weather and/or power line issues
  • Generator malfunctions (unexpected trips – loss of multiple generation units)

The key reserves needed by the Eskom System Operator are the Instantaneous and Supplemental reserves.

Instantaneous Demand Response Programme

Load Providers contracted to respond to a fall in national system frequency cause by a sudden change in the balance between supply and demand.  The purpose of Instantaneous Reserve is to arrest the national system frequency at acceptable limits following a contingency, for example a generator trip. Load Providers must respond fully within 6 seconds and must be sustained for at least 10 minutes.

Supplemental Demand Response Programme

Load Providers that can respond within a notice period of 30 minutes to six hours to restore other reserves. This reserve remains utilised until it can be replaced by other capacity or for a maximum duration agreed with the supplier. It is contracted annually with the supplier and bid available day-ahead. It is required to ensure an acceptable day-ahead risk, and to allow time for cold reserve plant to be called up.