| While most research on solar energy has been concentrated on smoothing intermittent power being pushed into the power grid, this research is focused on improving the complete integration of solar energy into the power grid by dispatching, or supplying a constant level of power, for 1-hour time periods. A hybrid energy storage system (HESS), consisting of lead-acid batteries and supercapacitors, will absorb and supply the necessary levels of power to keep the systems output power constant. The demand on the overall HESS and the two components in HESS, lead-acid batteries and supercapacitors, will maintain the constant level of power to dispatch. The predicted level of output power, for a one hour dispatching period, is determined by an estimation algorithm that uses actual solar data from Oak Ridge National Laboratory collected every minute throughout the day. This research shows results from June 9th, 2015, June 10th, 2015, June 12th, 2015, and December 25th, 2015 between 5:00 AM and 7:59 PM [3]. The estimation algorithm incorporates the solar irradiance and temperature to estimate the PV arrays average output power and its efficiency. The demand on the HESS is sent through a low-pass filter with a time constant of 1-minute that is then used as the reference for the lead-acid batteries. The remaining demand on the HESS is used as the reference for the supercapacitors. This utilizes the lead-acid batteries high energy density property, or slow charge/discharge rates at high energy levels, and the supercapacitors high power density property, or rapid charge/discharge rates at low energy levels [1, 4]. |
