Forecasting based power ramp-rate control for PV systems without energy storage

The intermittency of solar photovoltaic (PV) power generation causes problems to the grid, especially for the islands or weak grids. The utilities have imposed ramp limitations in some countries or regions, such as Germany, Puerto Rico, Ireland, Hawaii, etc. There are three ways to achieve power ramp-rate control (PRRC), one is by using energy storage system (ESS), the second is active power curtailment, and the third is by using ESS-MPPT hybrid system. The use of ESS is still too expensive for utilities-level real power compensation. It requires maintenance and has limited lifetime. The conventional active power curtailment cannot deal with power drops. In this project, we proposed a PRRC method which does not require any ESS. The PV generation is curtailed before the actual shading occurs by using a forecasting system. The curtailed PV generation has been evaluated by using a case study. The proposed PRRC can limit the ramp-rate effectively. The curtailed generation can be very small in certain cases which could make it has the advantage over ESS.