الفهرس | Only 14 pages are availabe for public view |
Abstract Recently, the Distributed Generation (DG) give a solution to the problem of continuously increased power demand in electrical networks. Microturbine units (MTU) which are suitable for DG application requirements, have been very popular for the power consumers because of their flexibility, compact design and low maintenance. Different interface systems could be used to link the MTU with the grid. Examples of these are conventional DCAC converters (inverters), High Frequency Link Converters (HFLC), Matrix Converters (MC) and back-to-back converters. Back-to back converters have advantages of controlling the active and reactive power, ride through faults and elimination of harmonics at the generator side. This thesis presents an interface system for a microturbine unit based on back-to-back converters to operate in grid connected and islanding modes. Besides regulating the active power fed from the MTU, during the grid-connected mode, the proposed interface system regulates the Point of Common Coupling (PCC) voltage at its rated value. Moreover, the proposed interface system is controlled to have a Low Voltage Ride-Through (LVRT) capability by feeding the grid with reactive power during grid faults. Furthermore, the proposed interface system keeps the voltage and frequency at the load terminal during the islanding mode of operation with the same control structure. Simulation results are provided to evaluate the dynamic performance of the proposed MTU interface system at the different modes of operation. Finally, the proposed interface system succeeded to transfer between the islanding and the grid connected modes without overshoots. |