Power system requirements and associated services at generator level in France

Operating a power system means insuring its balance at every moment. This is done by automatic controls as regards phenomena with short time constants (from a few seconds to a few minutes) and by the system operator for larger timescales. Therefore the generating units must be able to participate in these controls and remain connected under disturbed conditions. In other words: the system must be able to rely on `despatchable´ generators; and in order that a generator is `despatchable´, providing such services as voltage and frequency control cannot be separated from generating energy and power. This is why the authors prefer to call these services `associated services´ rather than `ancillary services´. The aim of this paper is to review and briefly describe them according to EDF´s practice. The authors first consider the requirements for usual situations (which they call `normal´ situations) and then those related to disturbed network conditions