Power control strategy of photovoltaic plants for frequency regulation in a hybrid power system

Abstract

The share of photovoltaic sources in power supply networks is increasing during the past few decades. This has resulted in the reduction of rotational inertia of the power system and thereby affecting the system frequency regulation capability. In view of this, there is an increasing need for PV also participating in frequency regulation of the system. In this paper, a power control strategy of PV has been formulated for frequency regulation without any energy storage system. The proposed controller derives droop and inertial response from the PV by operating it at a reduced level of power reserve without forfeiting system stability and economic benefits. To assess the effectiveness of the proposed controller, an IEEE 14-bus test system is considered and load disturbances were investigated through simulation studies. The bus system is extended to a more realistic network by incorporating different generating units and has also considered various non-linearities such as Generation Rate Constraint, Governor Dead Band, and delay in Area Control Error signal. The results show that the combined control of droop and inertial response from PV system contributes in a better way for frequency control. The superiority of the proposed controller has been demonstrated by comparing the results with the recently published frequency control regulation with PV. It is observed from the simulation results that the proposed control provides a better response. Also, sensitivity analysis is performed to investigate the robustness of the controller to variations in system parameters from nominal values. Finally, an economic analysis is carried out to study the prospect of PV participating in ancillary services.