ABB, Deltamarin, and VTT Simulate and Optimize Ship Energy Flows

Increasing a ship’s cargo capacity can reduce unit operating costs, but larger ships require more complex power plants with more sophisticated mechanical, electrical, hydraulic, and thermohydraulic subsystems. Because the behavior of these subsystems is interdependent, improving the performance of one subsystem may actually reduce overall efficiency. As a result, selecting and dimensioning propulsion, main power systems, all the auxiliaries, and cooling and heating for new and existing ships is a challenging optimization problem.

In the past, engineers used spreadsheets to calculate ranges for component sizes, but they found several drawbacks with this approach. The spreadsheets were not always reusable across projects, and colleagues found them difficult to review and understand. The approach was impractical for analyzing the system at various ship speeds and drafts or under wind, sea state, and other operating conditions. Spreadsheets were not suitable for dynamic analysis, and they could not be compared with data measured at sea or used to develop control systems.

To understand and identify interactions between different subsystems, Deltamarin, ABB, and VTT needed to model the complete ship energy flow with mechanical, electrical, hydraulic, thermal, pneumatic, and thermohydraulic components. They then needed to simulate this multidomain physical model to perform system-level optimizations.

A small team of engineers from ABB, Deltamarin, and VTT built the ship energy flow simulator using Simulink and Simscape. Working in Simulink, the team created a top-level model incorporating the main engine, diesel generator, electric alternating current (AC), propeller, cooling water, and steam subsystems.

该团队开发了基于使用机械，电气，热，气动和液压结构域的Simscapt块的第一个原理的组件模型。它们使用从实际船舶系统中取出的测量来设置模型中的参数值并验证仿真结果。

“One advantage of creating the models based on first principles is that the models are easy to understand,” says Guangrong Zou, research scientist at VTT. “We can clearly see how well a Simscape model is working even if we do not have measurements to fully validate it.”

Using the Simscape language, they defined three custom physical domains—thermalfluid, steam, and electrical AC—and built libraries of new Simscape components based on those domain definitions, including a new thermalfluid library with more than 50 components.

该团队开发了MATLAB脚本以自动化模型配置和模拟运行。他们还使用MATLAB生成图和后处理仿真结果。

为了满足使用电子表格执行能量平衡方程的船舶设计师的需求，该团队对模拟器建立了一个接口，使设计人员能够在微软提供仿真输入和审查仿真输出^®excel.^®。

The group has modeled and performed energy flow simulations for cruise ships, container ships, and other ship types, and ABB is using the simulator with its onboard Energy Monitoring and Management (EMMA™) system to understand the efficiency of existing vessels.