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3.5. Adequacy and safety of the electric system

The legislation distinguishes the concepts of adequacy and safety of the electric system; deriving the latter to the implementation of ancillary services (SSCC). These concepts are explicitly defined in the current legislation [34]

  • Adequacy: attribute of an electric system whose facilities are adequate to supply its demand.
  • Service security: responsiveness of an electric system, or part of it, to support contingencies and minimize consumption loss through backups and ancillary services.
  • Supplementary Services (SSCC): benefits that allow the coordination of the operation of the system. At least ancillary services include frequency control, voltage control and service recovery plan, both under normal operating conditions and before contingencies. These services will be provided by means of the technical resources required in the operation of the electric system, such as the capacity of active power generation, capacity of injection or absorption of reactive power or connected power of users, among others, and by the infrastructure associated to the provision of the technical resource.

In other words, adequacy corresponds to the ability of the system to supply the entire electrical demand and the energy requirements of the consumers at all times, considering programmed outputs of components and outputs that are not programmed but reasonably expected. Safety, on the other hand, is understood as the ability of the electrical system to withstand surprising disturbances such as electric short-circuits or unexpected loss of system components or disconnection operations.

The adequacy attribute is associated to a capacity payment, this payment focuses on the recognition, in terms of power, of the contribution of the different generators to the tip demand of the system and is valued in terms of the investment costs of the generation unit used for the system’s peak hours. In the security attribute, its payment should be through the recognition of Ancillary Services.

Until January 2016 in the Chilean electric sector, the attributes of safety and adequacy, were grouped under the concept of firm power. This is despite the fact that the LGSE differentiates both concepts since the regulation to define the recognition of the sufficiency attribute (S.D. N°62 of 2006 [35]) has been published since 2006. However, it was necessary to wait until ancillary services were defined and implemented to achieve to separate both concepts in practice. This happened in January 2016, with the publication of the Technical Standard of Power Transfer between Generating Companies.

Depending on the type of power plant and the resource used, each power plant will provide different powers for the system. Therefore, S.D. N°62 of 2006 defines the guidelines for determining the adequacy power of each type of power plant and thus power transfers between companies. The latter is determined from the adequacy power and existing peak demand commitments. In this way, each owner of generation means must be able to satisfy his own commitments for peak demand considering its adequacy power and that acquired to other companies.

Each generating unit is assigned an adequacy power depending on the uncertainty associated with the availability of the main input of generation that is used and the unavailability of the unit and the installations that interconnect it, characterized by the initial power and the preliminary adequacy power, respectively. For example, the adequacy power of hydroelectric plants will depend on their ability to regulate. A plant with a high capacity of regulation can contribute greater adequacy than a hydroelectric plant without capacity of regulation. The general scheme of the procedure of calculation of adequacy power that establishes the S.D. N°62 is illustrated in Figure 16. The stages and concepts used in the calculation process of adequeacy power for each type of power plant are described in more detail in Annex 3.

The National Energy Commission (CNE) is responsible for defining ancillary services and their categories, based on the Coordinator’s report, considering the safety and quality requirements of the electric systems and the technological characteristics of these services. At least ancillary services include frequency control, voltage control and service recovery plan, both under normal operating conditions and before contingencies.

For its part, the Coordinator must prepare an annual report stating the services required by the electric system, the technical resources necessary for the provision of these services, the infrastructure that must be installed for its provision and its useful life. In addition, the report must indicate for each of the required services the mechanism through which its service will materialize.

To this end, the Law of July 2016 enabled the Coordinator to conduct tenders or auctions when the request is of a very short term. Exceptionally, and only when the market conditions are not competitive or the tenders or auctions are declared as deserted, the benefit can be directly instructed. Subsequently, in March 2019, a new regulation of ancillary services was approved (DS N°113 of 2017). . This regulation establishes the way in which the services required by the system and the mechanisms for providing and/or installing them will be defined. It also establishes how the auctions, tenders and the provision and/or direct installation of the required services will be carried out.

The valuation of the complementary services that are auctioned or tendered will correspond to the value awarded in the respective tender or auction. Regarding the services that must be rendered or installed directly (without bidding process), they will be valued by means of a study of efficiency costs.