Hydropower Inventory Studies are one of the first phases in the process of Generation Expansion Planning. The position of these studies at the beginning of the planning decision process gives them a strategic nature since, at this time, resources have not yet been committed to the implementation of any future hydropower projects which shall make up the river basin cascade option. It is therefore at this moment that all cascade options for that basin must be surveyed and studied in order to select the one with highest energetic, social and environmental efficiency.
The methods used in Inventory Studies are consolidated in the Manual for Hydropower Inventory Studies of River Basins, the last edition of which was reviewed in 2007. An English version of the Inventory Manual was released in 2010.
The main improvements in the 2007 revision of the Inventory Manual are:
• Adjustment of the method for socioenvironmental assessment of inventory studies to be compatible with the methodology for integrated environmental assessment, since both seek to analyze/assess socioenvironmental impacts of the implementation of hydropower plants in a basin;
• Development of a methodology for assessment of positive socioenvironmental impacts resulting from the implementation of hydropower plants.
• Better characterization of multiple water use scenarios on which the energetic assessment of alternatives and the assessment of positive socioenvironmental impacts should be performed;
• Update of spreadsheets/ plots for hydropower plant dimensioning and cost quantification;
• Introduction of a new multi-objective approach for final selection of the best cascade option: "Maximization of economic-energy efficiency while minimizing negative socioenvironmental impacts, taking into account positive socioenvironmental impacts due to implementing hydropower plants in the river basin".
SINV System was developed to assist in the elaboration of inventory studies. SINV is an official tool used by the Brazilian Energy Research Company (EPE), the Brazilian Ministry of Mines and Energy (MME), the Brazilian Electricity Regulatory Agency (Aneel) and other agencies for the execution of energy, socioenvironmental and comparison and selection of the best cascade option studies, following the methodology described in the Manual for Hydropower Inventory Studies of River Basins. The current version of SINV allows: energy dimensioning and analysis of economic feasibility of projects; economic assessment of cascade options; economic prioritization of the projects of a cascade option in order to plan feasibility studies; consideration of multiple water use scenarios; calculation of negative and positive socioenvironmental impact indices for each cascade option; comparison and selection of cascade options using a multi-objective approach.
SINV has seven functions for energy studies, which may be calculated using a simplified procedure during Preliminary Inventory Studies or by operation simulations during the stage of Final Inventory Studies:
• Firm Energy: calculates the firm energy of a given cascade option and the projects it contains;
• Live Storage Optimization: determines the live storage of the projects contained in a given cascade option;
• Energy Dimensioning: determines the live storage, reference head and installed capacity of the projects from a group of cascades.
• Live Storage Replenishment: checks whether the time taken to replenish the live storage of the reservoirs in a cascade option is lower than or equal to 36 consecutive months counted as of the end of the critical period of the reference system;
• Elimination: Calculates the energy-cost benefit index (ICB) of the projects in a given cascade option and identifies which projects’ ICB are greater than the reference unit cost, so that the user can eliminate these projects from the cascade;
• Economic-Energy Assessment: Calculates the ICB of the different cascade options under study and ranks them by their ICB values;
• Sequencing: After the final cascade has been selected, ranks the projects from this cascade by their ICB values.
For the socioenvironmental studies, SINV has two functions: calculation of the negative socioenvironmental impact index; and calculation of the positive socioenvironmental impact index.
The system also provides two functions for selecting the best cascade option. The Preliminary Multi-objective Analysis function is related to the stage of Preliminary Studies and allows the selection of cascades to be assessed in greater detail during Final Studies. The Final Multi-objective Analysis function allows selection of the best cascade, that will go on to the next stages of Generation Expansion Planning, based on the criteria of the Inventory Manual - 2007 Edition. Both functions use multi-objective analysis.
SINV has a graphical interface for Windows operating systems which starts from a main screen with a design area allowing users to represent the dam locations and river segments of the studied basin in a topologic diagram. Through specific screens, users can insert and edit data relating to the projects, the reference system, water resources and other necessary information. The selection of the cascades that will be used in Final Studies, using the preliminary multi-objective analysis, is done in a specific screen to assist the decision maker through this process. During the Final Studies, the multi-objective analysis allows visualization of changes in the hierarchy of cascades in relation to changes in the relative weights of each objective.
Relevant benefits of using SINV system include:
• Better planning of the development of hydroelectric potential;
• Automation of energy, socioenvironmental and comparison and selection of cascade options studies in Inventory Studies;
• Facility to perform sensitivity analyses, seeking the selection of more robust cascades that meet in the energy and socioenvironmental requirements;
• Facility and standardization in the storage of used information, supporting the analysis of Inventory Studies by the institution responsible for their approval and future revisions of Inventory Studies.
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