Toshiaki Kanemoto

Simultaneous efficiency improvement of pump and turbine modes for a counter-rotating type pump-turbine

This article presents a multi-objective optimization to improve the hydrodynamic performance of a counter-rotating type pump-turbine operated in pump and turbine modes. The hub and tip blade angles of impellers/runners with four blades, which were extracted through a sensitivity test, were optimized using a hybrid multi-objective genetic algorithm with a surrogate model based on Latin hypercube sampling. Three-dimensional steady incompressible Reynolds-averaged Navier–Stokes equations with the shear stress transport turbulence model were discretized via finite volume approximations and solved on a hexahedral grid to analyze the flow in the pump-turbine domain. For the major hydrodynamic performance parameters, the pump and turbine efficiencies were selected as the objective functions. Global Pareto-optimal solutions were searched using the response surface approximation surrogate model with the non-dominated sorting genetic algorithm, which is a multi-objective genetic algorithm. The trade-off between the two objective functions was determined and described with regard to the Pareto-optimal solutions. As a result, the pump and turbine efficiencies for the arbitrarily selected optimum designs in the Pareto-optimal solutions were increased as compared with the reference design.

Optimized Blade Design of Counter-Rotating-Type Pump-Turbine Unit Operating in Pump and Turbine Modes

In this study, a counter-rotating-type pump-turbine unit was optimized to improve the pump and turbine mode efficiencies simultaneously. Numerical analysis was carried out by solving three-dimensional Reynolds-averaged Navier–Stokes equations using the shear stress turbulence model. The hub and tip blade angles of the rear impeller (in the pump mode) were selected as the design variables by conducting a sensitivity test. An optimization process based on steady flow analysis was conducted using a radial basis neural network surrogate model with Latin hypercube sampling. The pump and turbine mode efficiencies of the unit were selected as the objective functions and they combined into a single specific objective function with the weighting factors. Consequently, the pump and turbine mode efficiencies of the optimum design increased simultaneously at overall range of flow rate, except for low flow rate of turbine mode, compared to the reference design.

128 Power Stabilization System with Counter-Rotating Type Flow Pump-Turbine

1. 緒言 地球温暖化防止に向けてクリーンエネルギー資源の有効 利用が不可欠であるが,太陽光や風力などの自然エネルギ ー資源による電力には不安定性が付きまとう. このことを踏まえ,本一連の研究では相反転方式ポンプ 水車ユニットによる瞬時電力安定化システムの構築を目指 している.相反転方式は内外二重の回転電機子が互いに逆 方向に回転し,相反トルクが一致する点で運転される.ポ ンプ運転時には,流量に応じて前後段羽根車の回転速度が 自己調節され,不安定特性の抑制が期待できる.また水 車運転時には,磁界を切る相対速度が増大し,発電機径の 縮小,あるいは起電圧の増大が期待できる.さらに,両回 転電機子/前後羽根車の回転トルクが相殺されるため,ケー シング支持が容易となるなど多くの利点を有している. 本報告では、実証試験機のポンプ水車性能の基本性能把 握と,それより導いた平滑化運転を実現するためのポンプ 水車運転指標の一例を提案することにした.