A grid tie micro inverter with reactive power control capability

The focus of this paper is a 350VA rated grid tie micro inverter for residential photovoltaic installations with reactive power control capability. The need for reactive power control of small distributed generation systems stems from the opportunity to provide localized distribution network stabilization and reduction of transmission line losses. The selection of power components and modulation strategy is fundamental to realize a micro inverter capable of reactive power control while maintaining high efficiency and reliability. In the proposed design, these goals are achieved by implementing a DQ digital control scheme which allows decoupled management of active and reactive power and by accurate design of the power stage. The topology is based on an isolated interleaved boost converter and a Full Bridge PWM inverter. The power components selection and control strategy are discussed through the paper to address an effective implementation of a micro inverter with such characteristics. A new pre-charge method for the interleaved boost converter is also proposed. Experimental results support the suitability of such an approach.