Development Of Intelligent PV-interface In DC Micro-grid

With the great development of the photovoltaic generation technology and the increasing thetotal installed capacity, leading to improve the distributed grid-connection generation percentage inthe power grid, it’s necessary for adopting the isolated measures to reduce the influence for the power.It must be out of the power when the power failure, the advantages of the distributed generation willbe limited. In order to solve the issue, it can be made up a micro-grid. A novel structure of the DCmicro-grid system using Solar energy for the enterprise is proposed, the system configuration, thepower electronics interface is designed and for the Solar cells and high DC bus voltage, including lotsof principles for MPPT, the overall control strategy, the communcation and monitor for the system.The selection of the topologies for the photovoltaic interface converter is introduced. A novelstructure using two full-bridge rectifier circuits which are series connection is proposed, at the sametime, the small signal mathematic model for the push-pull DC/DC converter is build by state-spaceaveraging method. On this basis, the specific parameters and the design methods and processes for thepower circuit are emphasis introduced. There are lots of problems for the secondary rectifier diodes,the transformer magnetic bias and the voltage spike for the MOSFET which are analyzed and solved,and the main circuit simulation by Saber software is achieved.The equivalent model of the Solar cells and its output characteristics is verified throughsimulation, and the principle of the MPPT is introduced, on this basis, the commonly used methodsfor the MPPT are analyzed. Further, a novel variable structure and parameters fuzzy control algorithmfor the MPPT is proposed. Last the system overall control strategy is proposed.The digital control system for the push-pull DC/DC converter is designed which depend ondigital control controller dsPIC30F2023. The digital PI control algorithm is introduced and theparameters of the PI controller is designed and determined. And the wireless communication of theZigBee and the digital algorithm of the current share control are analyzed. At last, the softwareprogram, control algorithm and the remote monitoring system are designed, the experimentalprototype is developed and manufactured, and the experimental platform is build, the validity andfeasibility for the principles and the design of the software and hardware are verified.