Deriving Rule Curve for Hydropower Reservoirs: Seymareh Experience

A common method of design and operation of hydropower dams in Iran is based on peaking hours. In other words, monthly network demand (peak hours multiplied in install capacity) will be fully produced if the water level of reservoir in that month is between Minimum Operating Level (MOL) and Normal Water Level (NWL). If it is located under MOL or above NWL, the water level will be fixed on MOL or NWL and energy production will be lowered or increased, respectively. In order to take into account different monthly values of energy, implementing of an operating policy and rule curve is indispensable. The main goal of this study is to derive a set of monthly target storage elevation as a rule curve to operate the powerplant of Seymareh reservoir in West-South of Iran. The main simulation model of Seymareh reservoir and powerplant is developed in Vensim Environment using System Dynamics (SD) approach. In this process, all the technical and practical details of this reservoir are taken into account. Relations between discharge and turbine efficiency and tail water, volume-area-elevation relations, reservoir evaporation, overload coefficient and maximum and minimum allowable head and turbine discharge are some of these details. Energy production will be occurred if the water elevation of a particular month of reservoir is located above the defined target elevation of that month. This process is performed on historical time series aiming to maximize mean annual value of generated energy. In the next part of this study, to avoid the trial and error process of target elevation selection of above discussed simulation model, a simple ACO algorithm with an embedded coded simulation model is implemented. Results show the ability of this algorithm in defining a rule curve for an absolutely practical case study.