Research On Characteristics Of Shipborne Solar Photovoltaic System In Marine Environment

Since its start in the1990s, the solar ship built based on different kinds of hull structure has been invested in long-term experimental research or commercial operation, which provided both demonstration and guidance for using another clean energy on the ship. For the ocean-going vessels especially, the marine environment and application platform issues should be regarded as the initial point when establishing the solar photovoltaic grid-connected system based on a ship power system, containing:(1) Output characteristics of solar cell under the effect of marine environment.(2) The performance characteristics of ship power system with solar photovoltaic (grid-connected) system (SPS2) integrated at the different level of photovoltaic penetration, especially by applying different control strategy for grid-connected.Correspondingly, the characteristic issues of shipborne solar photovoltaic system are set as the basic standpoint in this dissertation, and four aspects are contained during the research process:(1) The theoretical and mathematical models of solar photovoltaic cell are compared and analyzed, and a corresponding simulation model is established under the simulation environment of Matlab/Simulink. The algorithms of maximum power point tracking and DC/AC inverse are both achieved based on this simulation model.(2) The power output characteristics and mechanisms of solar cell under the effect of multiple environmental factors are studied via analysis of influencing factors, environmental simulation and comparative experiments. Based on more analysis and numerical solution, two theoretical models (Improved Energy Conservation Model and Parameter Correlation Model) are established to represent the interrelationship between five parameters and Ⅰ-Ⅴ equation of solar cell.(3) The technical specifications that relate to SPS2are stated in detail, and simulation models aiming at ship power system and solar photovoltaic system are established and analyzed via Matlab/Simulink environment respectively. Further, a ro-ro passenger ship is defined as the prototype for building SPS2generalized simulation model based on its structural model, which is derived from Integrated Power System (IPS).(4) With the environmental factors involved in, the method of multi-model switching is applied to study the operation characteristics of grid-connected. Three sets of comparative experiments are conducted with the different simulation models, containing simplified ship grid, actual ship grid that composed of single-and multi-diesel generator.Three basic conclusions are contained, as following:(1) IPS can be treated as the technical platform for constructing high-penetration photovoltaics, but the specifications for ship classification and solar PV grid-connected system should be regarded as the fundamental guide for building SPS2. The intellectualized power system "SSG" is the most advanced form for realizing the integrated application of multiple renewable energy or green energy on a ship. In the implementation process of SSG, the Microgrid theory from the framework of SG can be taken as the reference substance.(2) The multiple factors related to marine environment can affect the cell temperature and solar irradiation intensity simultaneously, which deteriorate the power output characteristics of solar cell, such as fill factor and PV conversion efficiency.(3) Along with the increase of penetration, the PV grid-connected system that only applies the PQ control strategy will shock the ship power system observably. The inverter’s performance decides the parallel operation characteristics, as PV system is a zero inertia electrical power system. Thus, the operating stability of SPS2is greatly depended on the real-time control strategy of power system. The voltage and frequency of grid can be changed by regulating the speed of prime mover and the voltage output of excitation system, but the synchronous generator cannot individually compensate the power requirement of reactive load when the PV penetration is set at a relativly high level. Under this condition, a synchronous compensator should be inserted.