Load emulation technique for variable power factor and harmonic loads with energy recycling

The need for emulation of electrical load is often experienced in industrial design, development, and testing of electrical sources, especially in the case of renewable energy sources. The performance of standalone renewable energy systems is found to vary considerably with a change in load characteristics, especially with varying power factor (PF) and harmonics. Here a novel load emulation technique has been developed, using which variable PF and variable harmonic loads can be easily emulated and the energy drawn by the load can be recycled. In the proposed technique, the current drawn by the load is divided into in-phase, leading and lagging components. Each component is controlled individually. The in-phase power is then regenerated. The simulation and hardware results show exact variation in load characteristics as per the test requirements, which are difficult or impossible using passive loading and existing load emulation techniques with back to back converters. The proposed method is found to be more accurate, flexible and easier for emulation of low PF and high harmonic loads. A performance study is also conducted on a solar photovoltaic system using the developed model, substantiating the importance of this load emulation method.