Power smoothing techniques to mitigate solar intermittency

Intermittency is an important issue in a photovoltaic (PV) system, as the production of electrical power is highly dependent on the sunlight intensity. Solar intermittency is even critical in the absence of an energy storage system. Therefore in this paper a battery energy storage system (BESS) is incorporated to mitigate the solar intermittency and to reduce power fluctuation in grid. The proposed PV system comprises of PV array and connected to DC-DC boost converter using incremental conductance technique. A common DC bus is shared with the PV system and BESS, which is then fed to utility grid via three phase inverter. In BESS, three power smoothing techniques are implemented namely ramp-rate (RR) control, moving average (MA) and low pass filter (LPF). A smooth PV reference power is produced to generate the corresponding current references and to control the operation of bidirectional converter in the BESS. In addition, three phase grid-tied inverter is implemented using abc-dq0 transformation, PI controller and Phase Lock Loop (PLL) technique to maintain grid synchronization. The proposed system is simulated using MATLAB Simulink. This paper compares the effectiveness and efficiency of the three proposed smoothing techniques, and proved that the ramp rate control has better performance than moving average and low passes filter techniques in mitigating solar intermittency.