Control of photovoltaic system connected to DC bus in all-electric ship

In order to lower the operational costs and exhaust gas emissions from ships, electrification and inclusion of renewable energy systems is highly recommended. However, while combining solar energy systems and diesel generators in shipboard electrical systems is not a novel concept, most previous applications have used alternating current (AC) bus systems. Meanwhile, recent developments in power electronics have raised the possibility that direct current (DC) bus systems may be more economical than AC systems. In this paper, a control system for connecting photovoltaic (PV) power to a DC bus system is proposed. The control system consists of two layers, one for extracting maximum power from the PV source, and the other for maintaining stable DC bus voltage. Verification performed via computer simulations show that the proposed system can extract the maximum power from the PV source with a minimum 99% matching efficiency, and that the DC bus voltage can be maintained with a voltage drop below 2% of the 380 V rated voltage, as long as the PV array voltage is maintained above 95 V.