Abstract

The traditional, regulated electric power systems are based on large power generation plants located far from load centers. In a deregulated market, however, small and environmentally friendly power plants using wind power, photovoltaic cells, fuel cells and micro-turbines can be installed through a given distribution system. This concept of distributed generation tends to reduce the cost of electricity and to reduce or postpone major investments in the transmission system. Many of these small power plants are typically consumer owned and are connected to the utility grid by means of single-phase power electronic voltage source converters. This type of converter that supplies active power to the ac grid can also be controlled to provide active filtering and Var generation, thus enhancing the quality of the power at a given point and providing added value to the distributed power source. This Thesis focuses on the practical issues of a multi-featured single-phase utility interface. It focuses on three important aspects: (1) the management of the low order voltage harmonics present in the dc bus of the interface. (2) The design of fast and robust single phase phase-locked loop for the synchronization of the power interface. (3) A new control circuit for a three-level hysteresis current controller. Finally, a digital signal processor based prototype test circuit that satisfies all the aforementioned functions and allows active power filtering and reactive power compensation is built in the laboratory to demonstrate the effectiveness of the proposed techniques.