| Summary: | 碩士 === 國立聯合大學 === 電機工程學系碩士班 === 106 === In the future, with the government’s policy of energy conservation and carbon reduction, there is no room for expansion of Taiwan’s conventional power generations based on the fossil fuel. A more feasible direction goes to developing renewable energy based distributed power generation and micro-grid systems. It is obvious that the structure of the future power grid will be the coexistence of conventional power grids and a large number of small, medium-sized and clustered micro-grids. To achieve a better overall energy efficiency, system reliability and operational flexibility, it is an urgent need to develop hybrid power systems suitable for coexistence of AC and DC grids, high-performance power conversion interfaces and the related optimum operating and control strategies. Due to the unavoidable nature of output power variations in renewable energy based power generations, the appropriate design and integration of energy storage devices, the fast regulation of real-time power flow and the related intelligent power control schemes are key technologies for sustainable development of the renewable energy based distributed power systems and micro grids. In view of this, the research purpose of this thesis is to investigate an integrated control scheme for multiple power converters to be used in a small to medium-capacity, grid-connected renewable energy based power generating system. The overall system configuration investigated in this study includes a photovoltaic(PV) power generating unit, a battery energy storage unit, a grid-connected, single-phase converter and a power grid. In this thesis, various power converters required for the studied system are all designed with gallium nitride (GaN) based semiconductor devices to achieve high-efficiency and high-power density systems. The control unit of the system is designed with a DSP to achieve a fully digital and coordinated control scheme integrating multiple power converters. Based on the state of charge (SOC) of the energy storage unit and the operating conditions of the system, a number of possible operating modes and advanced power control functions are firstly developed. Then, the hardware configurations of the required power converters along with the required digital controllers are designed. The correctness of the designed controllers and the overall performance of the proposed control scheme are verified with comprehensive computer simulations, and followed by a set of hardware tests on an 1-kVA, small-capacity, experimental system with the TI DSP TMS320F28335 chip as the core controller. Typical results have been presented with discussions.
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