On Stability of Hybrid Power Ramp Rate Control for High Photovoltaic Penetrated Grid

This paper proposes a hybrid constant power generation - power ramp rate control (CPG-PRRC) scheme to regulate the ramp-rate of the power injected into the grid by a cluster of photovoltaic (PV) sources. The ramp-rate regulation of the injected PV active power is achieved dynamically in real-time under highly fluctuating PV ambient conditions and without considering PV forecasting data. The proposed hybrid CPG-PRRC control scheme integrates the concept of constant power generation with power ramp rate control to ensure mitigation of the potential voltage/ power fluctuations seen by the grid and protects it from source side instabilities. Moreover, the proposed scheme is capable of regulating the PV power ramp-rate within the set limit during power ramp-up as well as ramp-down scenarios and does so without the use of energy storage devices. The ramp-rate is regulated by maintaining the PV operation set– point on the left side of the maximum power point (MPP) and dynamically increasing or decreasing the power reference at a rate which is within the ramp limit. Furthermore, this paper addresses potential stability concerns for the PV architecture in hand with the CPG-PRRC. Several test scenarios are provided to verify the theoretical expectations.