Emergency supply means assistance from the TSOs of synchronously interconnected power systems with the aim of either supplying the power required to cover a shortage of power within the Czech power system or removing surplus power from it. This ancillary service can be activated if an unexpected operational situation occurs such as interconnector overloading, power lack/surplus within the power system, non-fulfilment of the N-1 criterion etc. This service is reciprocal and activation can also be requested by a TSO with which ČEPS has a signed agreement on emergency assistance.
The emergency assistance service is activated through the Control Centre of the respective TSO which notifies the counterparty of the volume of power required (in MW), the start date and time and the duration of emergency supply. Since such power is delivered over an interconnector, the export/import balance of the transmission systems involved has to be modified accordingly.
The power supplied is considered to be either the provision of positive regulation energy (which represents electricity import for the power system requiring AnS activation) or the provision of negative regulation energy (electricity export for the power system requiring AnS activation).
If this service is utilised by ČEPS, electricity supplied to or from the Czech power system is considered to be regulation energy delivered by ČEPS. For settlement purposes, such regulation energy is provided, and the price determined, by ČEPS. Energy delivered by a neighbouring TSO to the Czech power system can, in certain cases, be subsequently returned to the neighbouring TSO.