Hybrid Systems

When designing a gas/diesel mechanical propulsion plant its often easy to optimize both engine and propeller separately. When combining the two with the hull performance curves and running profiles of the vessel there are many areas in which either the propeller of the engine must be used outside the optimum conditions to meet the demands of the operational profile.

The use of a drive between the electric machine coupled to the PTI/PTO shaft of the main gearbox and the main switchboard decouples the rpm requirements associated with traditional shaft generators. And the result is that propeller and engine efficiency can be optimized over a larger power area than earlier. Another advantage of utilizing a drive on the main gearbox electric machine is that this machine can be used as a low power propulsion device when propulsion demand is low, making it possible to use diesel generators as main propulsion in the lower range of propulsion load range.

With Høglund Energy Storage System connected to the DC link of the shaft generator enables the Energy Management System to smooth out load changes seen be the combustion engine reducing consumption and mechanical wear as an effect. This effect is best shown then operation vessel in bad weather where usually the main engine will need to take the variating load being induced by the seas hitting the vessel. The ESS can also be used when ship is alongside either with or without shore connection. The diesel generators can then be controlled to start and charge the ESS when SOC level is getting low, and then recharge ESS to a set SOC target level and then stop again. This operation mode reduces running hours on the generators as well as noise and air pollution of the harbor in which the ship is docked.