Multi-functional double mode inverter for power quality enhancement in smart-grid applications

This paper introduces a new multi-functional double mode inverter (MFDMI) scheme, which is able to operate under a variety of operational conditions for aggregation of PV-based renewable energy resources. Detecting islanded situation within a new and fast approach, regulating the voltage in the islanded mode, smooth transition between islanded and grid-tied (GT) modes, injecting both active and reactive powers to the grid in addition to compensating the harmonics from nonlinear loads are beyond the most notable functionalities of the proposed framework. Technically, we exploit a combinational control scheme formed by instantaneous power theory, vector-control and a proportional integral resonant (PIR) controller to address the required functionalities. To deal with the low output power issue, photovoltaic (PV) cells are aggregated through a high gain DC-DC floating interleaved boost converter (FIBC). Moreover, a battery back-up module with bidirectional DC-DC floating interleaved buck-boost converter (FIBBC) is used to improve the system reliability and dispatch ability. The effectiveness of the proposed framework has been first verified within a comprehensive PSIM simulation results and then has been examined under realistic situations using the real-time simulator OPAL-RT with DSP modules (hardware in the loop) for a broad range of conditions and within different practical scenarios.