J. Bione, J. Tomaz, T. Azevedo, J. Alves
Instituto Federal de Educação, Ciência e Tecnologia de Pernambuco - IFPE and Companhia Hidro Elétrica do São Francisco - Chesf,
Keywords: storage, substation
Summary:Since the 1980s, Chesf has been developing projects and research on renewable energy sources, with one of the emphasis on solar energy. These works distinguish it as a reference in the Northeast and as a prominent company in Brazil in power generation and which has historically made relevant contributions in the development of the country's electricity sector. In line with its clean energy generation sustainability policy, as outlined in its Vision / Mission and Strategic Planning, Chesf has been contributing to the fight against greenhouse gas emissions and adds its efforts to protect the global climate. Power substations connected to the National Power Transmission System - SIN are operated by the concessionaires in conjunction with the National Electric System Operator (ONS). The latter is also responsible for establishing the Grid Procedures, which in its sub-module 2.3 establishes, among other requirements, the possibilities of supplying the auxiliary direct current and alternating current services for substations of the mains, with nominal voltage equal to or higher. 230 kV: "Auxiliary AC services must have two power supplies, one local external and one tertiary from the substation transformation. If the substation has no transformation, the two power supplies must be external from separate substations. must be submitted by TRANSMITTER for review and approval by ONS and ANEEL. " In the context of the SIN, some 230/500 kV substations stand out, whose Auxiliary Services do not have an internal source to supply the installation's load. In this scenario, reference is made to transmission assets that are the result of concessions that precede the currently adopted Network Procedures. In this particular context, the arrangements for this type of substation were designed in such a way that, to ensure feasibility - or under regulatory conditions at the time - basic / executive projects did not provide for the quantity of three or more sources of internal supply and / or and the high voltage levels associated with the equipment topology substantially increase the voltage reduction for the AC Auxiliary Services. For such cases, the ONS has directed agents towards the adoption of alternative supply measures or the redundancy of these alternatives. In practice, additional emergency supply units are installed through power generators (known as GMG). GMGs are sized to meet the substation's essential loads and additional investments are required to implement automations, which require major interventions on energized panels. As cold reserves, GMGs act in contingencies after the absence of a voltage signal in the substation Auxiliary Services bar. In this scenario, during the event, there is an interruption in the auxiliary services power supply, that is, momentarily there is unavailability of alternating voltage in the installation. In addition to the points previously mentioned, the need to implement infrastructures for installation, maintenance and operation, increases the operating costs of the substation. Finally, reference is made to the consumption of fuel and petroleum products (lubricants and additives), which require proper treatment regarding their logistics, storage and disposal, as well as constant environmental and fire risk monitoring.