A proposal for analysis of operating reserve requirements considering renewable sources on supergrids

Hydroelectric and thermal generation provides a safe and regular operation in front of load shape. However, changes in the expansion policy that includes wind and solar power plants modify the path of transmission power flow and load response requirements. In order to accommodate these new renewable sources, long-term systemic approach is complex and should be based on hydrothermal optimization and load shape allocation. Recent studies show that these resources are not sufficient for the systemic needs. Energy storage can be an alternative to the regularization of renewable sources. The problem is to scale this equipment in a long-term scenario in a suitable way so as to charge a fair price for the service. At this point, operational reserve is fundamental, but often overlooked in hydrothermal expansion models. Current expansion planning models cannot adequately meet the new system demands, but they are critical for determining long-term prices, so they must be modernized and replaced gradually to avoid further problems. The paper proposes a transition approach from the current modeling through the inclusion of a new step in the expansion planning process, called the operational reserve analysis, which seeks to meet the load–generation balance criteria and to scale, if necessary, the use of additional storage devices. It is also proposed a power flow analysis to find optimal location in transmission grid, in addition to evaluating different storage devices needs and how transmission network expansion with multiple AC and DC that provides greater benefits to interconnected system. To validate proposed algorithm application, a case study was carried out for IEEE 14 bus database, and a real application was carried out for the Brazilian system, considering up-to-date planning tools and hourly allocation in load curves. This case demonstrates that the method is suitable as transition for new planning tools.