RESEARCH ON DECREASING THE COST PRICE FOR THE SYNCHRONOUS HYDROGENERATOR Buletinul AGIR nr. 4/2012 ● octombrie-decembrie 1 RESEARCH ON DECREASING THE COST PRICE FOR THE SYNCHRONOUS HYDROGENERATOR Elisabeta SPUNEI 1 , Laurenţiu PĂDEANU 1,3 , Florina PIROI 2 , Ion Piroi 1 , Gheorghe LIUBA 1 1 ”Eftimie Murgu” Univeristy, Reşiţa, Electrical Engineering and Informatics Facutly, Romania 2 Institute of Software Technology and Interactive Systems, Vienna University of Technology, Austria 3 Technical University Timişoara, Faculty of Electrotehnics and Electroenergetics, Romania ABSTRACT. A hydrogenerator’s cost price is considerably influenced by the used and computed design values. The most important parameters in the design of micro hydro power plants synchronous generators are the power blanket, the current density in the statoric winding and the air gap size. In this work we analyze the impact of these parameters on the cost price for a family of hydro power plant synchronous generator where the power is the same but the rotations vary. The conclusions we take offer information essential to the design phase of these micro hydro power plant hydrogenerators. Keywords: synchronous generato, rotation, optimal design, total cost, optimal parameters 1. INTRODUCTION Taking into account the European requirements regarding the material and energy restrictions [1] optimal design becomes an essential part in fulfilling this desideratum. When designing hydrogenerators the values chosen for its various parameters define its operating performances. In the optimal design we chose the objective function that minimizes the total cost, C t . This cost is computed as the sum of the manufacturing cost, C f , and the exploitation costs, C f [2]. After a detailed analysis we found that for a hydrogenerator equiping a micro hydro power plant of 353 kVA the most impact on the objective function is made by the following parameter combinations: the power blanket A and the air gap size δ, (a cost decrease of 20%); and the current density in the statoric winding J 1 and the air gap size δ (a cost decrease of 20.04%) [3]. Starting with various parameter combinations, we analyze in this work the impact the rotation has on the total cost when the hydrogenerator’s power is maintained constant and the initial variables are revised. For this we implemented the Complex optimal design algorithm. We chose the ( 0, 7 1, 2 x x    ) variation range for the values of the initial parameters of the existing hydrogenerators [3]. We compared the variable values and the afferent costs for seven classic synchronous hydrogenerators to the variable values and costs obtained using the optimal design. The seven studied micro hydro power plants hydrogenerators have a power of 300 kVA and 400 V voltage, a 50 Hz frequency, a 0.85 power factor and differ in their operating rotations: 250, 300, 375, 500, 600, 750, and 1000 rot/min. 2. OPTIMIZING ON THE POWER BLANKET AND THE AIR GAP SIZE While desigining a hydrogenerator, its parameter values are chosen according to the design specific literature chosen, to the design algorithm and to the designer’s expertise. The design manuals recommend that the power blanket ranges between 180 and 640 A/cm, for a polar pitch variation between 150 and 700 mm. The polar pitch size depends on the hydrogenerator inner diameter [4,5]: 2 D p      (1) while the diameter’s value depends on the number of pole pairs, p, and the rotation: 3 60 2 100 iN S p D nC         (2)