Research On High Efficiency Control Strategy Of Ship Electric Power Station Based On DC Power Grid

How to provide more power in a limited space on board is an eternal topic in the area of ship electric propulsion. As the load of ship power system increases year by year, this presents new challenges for the energy density of the ship power system. In recent years, some foreign electric companies have launched ship electric propulsion system related products based on DC power grid. The system has the advantages of high fuel efficiency and small space required, which can improve the energy density of the ship. In addition, the mechanical wear is small, vibration and noise is small, which makes the equipment a longer life. Economic efficiency has improved significantly. Therefore, the future prospects are very bright. However, there is not yet related product launch in this area. Related research on control strategy of ship power station based on DC power grid has never been reported. In this paper, an efficient control strategy of ship power station based on DC power grid has been studied by the method of simulation and experiment.In order to establish the mathematical model of the ship power system based on DC power grid, the mathematical model of diesel engine, speed regulator and excitation regulator were carefully analyzed firstly. Based on the analysis of fuel consumption curves and the trend of the maximum torque curve of a typical diesel generator, this paper proposes a control strategy, which makes the diesel generator set run stably and efficiently, namely inter-partition target control strategy. And the control strategy is realized in the simulation module.A module of diesel engine and speed regulator, excitation regulator module, and integrated controller module etc. are built in MATLAB. On this basis, a single machine simulation model of ship power station based on the DC power grid has been established. According to the load of water vessels’ various working conditions and the occupied proportion of time throughout the voyage by the sailing conditions, this paper established a sailing conditions table. The load of the simulation model is set reasonably based on the sailing conditions table. Simulation results verify the economy and feasibility of the ship electric propulsion system based on DC power grid. And the feasibility of the inter-partition target control strategy has also been inspected effectively.Taking into account the total amount of the load and the overall system efficiency issues, the ship power systems often adopt the mode of multiple sets of generators connected in parallel. The generator sets will be put into operation or removed from the grid according to the level of the load. By analyzing the power distribution law in the case of multiple sets of diesel generators operating in parallel, a double machine simulation model of ship power station based on the DC power grid has been built on the basis of single machine simulation model. Simulation results verify the feasibility of multiple generators sets running in parallel in the ship power station based DC power grid, and this model can also distribute the load evenly.On the basis of simulation, an experiment platform for the ship power station based on the DC power grid is built. Experiments proved the feasibility and reliability of the ship power station system. And the experiments have also tested the feasibility of inter-partition target control strategy proposed in this paper. By comparing the fuel consumption of two different systems worked under same load, it can be concluded that the oil consumption rate of ship power station based on DC power grid is lower than the ship power station based on AC power grid. And the former has obvious economic benefits, especially for vessels operate at low load rate frequently.