With the high penetration of renewable energy in modern power systems, the necessity for photovoltaics (PVs) to support system frequency tends to be apparent. In view of limited available energy, the manner for PVs to participate the system supporting deserves studies. In this paper, a frequency supporting strategy of the grid-connected PVs based on optimal control and predictive algorithm is proposed. Considering the constraints of available energy and the objective to mitigate the frequency deviation, an optimization model is formulated to derive the optimal reference for PV outputs by Gauss pseudo-spectral method. On this basis, the model predictive control strategy is used to track the optimal reference curve, which is expected to demonstrate a better dynamic response. Finally, a simulation example is constructed in PSCAD/EMTDC to validate the correctness and the superiority of the proposed frequency supporting strategy for PVs.

frequency regulation; Gauss pseudo-spectral method; grid-connected photovoltaics; model predictive control; optimization model