A Power Ramp Rate Control Strategy with Reduced Energy Storage Utilization for Grid-Connected Photovoltaic Systems

Fluctuations in photovoltaic (PV) power generation are inevitable due to intermittent irradiance transients. These power fluctuations, when injected into the grid in grid-connected PV systems, can have a negative impact on grid stability. This issue becomes more prominent in grids with high PV penetration. Therefore, this article proposes a hybrid power ramp rate control (PRRC) strategy that mitigates the fluctuating PV power at the dc-side before transmitting it to the grid during positive and negative irradiance changes. The proposed hybrid PRRC aims to reduce the energy storage system (ESS) utilization and its required capacity by employing a flexible power point tracking control, which limits the increment in PV power generation during positive irradiance fluctuations. A supercapacitor (SC)-based ESS is only used to smoothen the power reductions during negative irradiance fluctuations, and the SC state-of-charge is regulated afterwards to prevent saturation. The transient performance and efficacy of the proposed hybrid PRRC are investigated using simulations in MATLAB/Simulink.