Proposed Ancillary Services for the Southern African Power Pool

This paper describes the recent developments and proposals for Ancillary Services trading between Southern African Power Pool (SAPP) members. Ancillary services are the services, apart from energy, required to maintain reliability of the interconnected power system. Reactive power and operating reserve services maintain voltage and frequency of the interconnection within acceptable levels and in the event of a blackout, Black Start is the service required to restore power to the interconnection. The set of Ancillary Services proposed for SAPP is Reactive Power and Voltage Control, Black Start and three Operating Reserve services (Instantaneous Reserves, Regulation Reserves and Ten Minute Reserve). Traditionally Ancillary Services are provided by utility owned generators but potential suppliers of Ancillary Services could be expanded to demand side options, distributed generators and also via HVDC networks. Before Ancillary Services can be traded between utilities there is a need to ensure the trade is technically possible and further that this trade will not negatively impact on the reliability of the interconnection. The studies and process required to determine if Ancillary Services can be technically traded without adversely affecting reliability are described in the paper. The paper describes the proposed intermediate set of trading arrangements for SAPP and how future long term trading arrangements could be implemented.