Page - 524 - in Book of Full Papers - Symposium Hydro Engineering

There are several statistics to identify the efficiency of a model. In this research we examined the goodness of fit with Nash-Sutcliff measure (Reff), coefficient of determination (R2) and mean annual difference (Mdiff). 2 2 ))(( ))()(( 1       ObsObs ObsSim eff QtQ tQtQ R (1)         22 2 2 )()( ))()(( SimSimObsObs SimSimObsObs QQQQ QQQQ R (2) 365 )( n QQ M SimObs diff    (3) 2.5. MODELING TWO RESERVOIRS SYSTEM IN VENSIM To calculate the hydropower generation, two reservoirs system of Bakhtiari and Dez dam were developed in Vensim by entering the equations of mass balance and power generation, considering the restrictions of operation of the reservoirs and power plants. ttttttt ADDEVAPSPLRDREQS         1tS (4) Where, St+1: The reservoir volume at the end of t period (beginning of the t+1 period); St: The reservoir volume at the beginning of t period; Qt: Inflow to the reservoir during t period; REt: The outflow from the reservoir to generate energy during t period; RDt: The outflow from the reservoir to meet downstream demand during t period; SPLt: The spill from the reservoir during t period; EVAPt: Evaporation from the reservoir during t period; ADDt: The volume of added flow from upstream reservoir during t period. The power generation is associated to the installed capacity, efficiency, plant factor as well as the inflow and hydraulic head. Equation below shows the power generation which was used to calculate the energy generation. 1000)(Pt ttt eHQ  (5) Where, Pt: Power generated during t period; γ: Water specific weight; Qt: the inflow to the turbine during t period; Ht: Net hydraulic head on turbine during t period; et :The power plant efficiency. 524