Ancillary services: the Spanish perspective [electricity supply]

The Spanish electrical system is immersed in a period of change as a result of the passage of the Spanish Electricity Act. Among the main changes brought by this Act is the mandatory separation of different activities carried out within the electrical power system, inclusion of free market mechanisms, the creation of the National Electric System Commission as an independent regulating body and the creation of an independent system designed to coexist with the current integrated system. The creation of the independent system and the possibility for some `eligible´ customers of the integrated system to purchase electrical energy in this system for an integrated value of the energy, a form of wholesale tariff, will require the creation of mechanisms to allow for free access to transmission and distribution networks, for which the proper toll systems must be defined. All possible exchanges between the two systems should also be regulated, including those which may arise from the sale of ancillary services, supplied between the two systems. The manner in which such ancillary services are dealt with is discussed by the author in this paper