船舶發電機容量節能設計

SIZING OF POWER GENERATORS FOR ENERGY SAVINGS IN SHIP POWER SYSTEMS

船舶電力系統設計的最基本工作之一是藉由電力負載分析（electrical load analysis）來決定船上所需的發電裝置容量。這類的分析以設備成本及供電裕度為主要考量，通常採用多部相同發電機組容量為設計，並未考慮機組運轉效率，使得於重載作業狀況下之運轉效率較低，造成能源的浪費。為提升發電效率及降低能源成本，本文提出一套船舶發電機組容量節能設計方法。該方法首先利用泵浦理論公式計算泵浦系統所需之電功率，並將節能觀念導入於負載分析設計中。該負載分析設計被模式化成一個組合式不可微分最佳化問題，以船舶整航次總發電成本為目標函數，在考慮系統所有可能的運轉限制下，利用基因演算法（GeneticAlgorithms, GAs）推導出最適發電機組裝置容量組合及調派排程。藉由本文提出的方法，工程師可決定出適當的船舶發電機組裝置容量及調派，以降低發電成本，將有助於提升船舶能源使用效率。一艘大型實際商船電力系統被選為研究對象進行實例分析，以確認及展示本文提出的方法之執行效能。 One of the most basic tasks for ship electric power system design is electrical load analyses to determine on-board generator installed capacity required. Traditionally, the analysis is performed based on consideration of costs and the same rated power design is usually used. It does not consider the operation efficiency and energy conservation, which results in the generators operated at lower efficiency under some operating conditions and more energy is consumed. To enhance generator energy efficiency and reduce prime mover fuel consumption required, a set of energy-saving analysis model based on electrical load analysis is proposed in this paper. The analysis model uses the pump theoretical formulas to develop the accurate load demand estimate model and introduces energy-saving concepts into the electrical load analysis. The problem is formulated as a combinatorial optimization problem with non-differential objective function, where the total generation cost during a whole voyage is minimized subject to all possible system operation constraints to derive the optimal rated power and unit commitment for the generators by genetic algorithms. The proposed model can allow engineers to determine proper generator rated power and unit commitment to effectively reduce the generation fuel, which greatly enhances the energy efficiency in ships. A practical power system of large commercial vessels is selected for the study to ensure and demonstrate the performance of proposed method.