Use of Energy Storage in a LVDC Distribution Network for Ships
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- Institutt for elkraftteknikk 
This thesis has focused on the modeling of energy storage technologies such as Li-ion batteries and super capacitors, where they are connected to a DC bus with a bidirectional DC-DC converter. Two different energy storage operation strategies such as peak shaving and load sharing were studied. With a peak shaving strategy, super capacitors and high power Li-ion batteries were tested and compared, for relieving the diesel generators from load variations. With a load sharing strategy, high energy Li-ion batteries in combination with super capacitors were studied, for replacing one diesel generator. The effect of these energy storage strategies were studied for an operation time equal to one year, in seven different load operation modes. Due to this long time duration, the simulations were carried out in a MATLAB program by using average modeling. The simulation results of interest were; the reduction in fuel oil consumption for different diesel generators operated with variable or fixed speed, the DC-DC converter efficiency, temperature, cooling requirement and size of the energy storage. From the simulation results and the assumptions made, it was shown possible to reduce the fuel oil consumption in ships application by applying energy storage. This is however dependent on the system setup, as the reduction in fuel oil consumption showed a dependence between the diesel generators operation mode, vessel?s electric load demand and the energy storage operation strategy.