Power reserve control with real-time iterative estimation for PV system participation in frequency regulation

Abstract

Due to the increasing penetration of photovoltaic (PV) systems, PV plants are required to provide a full range of ancillary services to power grids, including frequency support services, which must maintain a certain power reserve. The existing power reserve control (PRC) methods have some shortcomings. Some PRC methods need irradiance and temperature sensors, and some methods involve complex model estimation. Furthermore, rapid and continuous change in irradiance diminishes the accuracy and stability of PRC methods. In this paper, a novel power reserve control for PV power plants is proposed. In contrast to existing PRC methods, the proposed PRC strategy does not require an irradiance sensor or complex mathematical calculations. Only one sampling point is required for each estimation process. The proposed PRC can track a given power reserve ratio even if the irradiance changes rapidly and continuously. Several sets of simulations were performed under different conditions, and the results show that the proposed PRC achieves fast tracking speed (within 50 ms) and high tracking accuracy (steady-state error below 1%). The proposed PRC has been integrated into a frequency regulation scheme to provide frequency support service. The effectiveness of the proposed frequency regulation scheme is demonstrated through case studies on an IEEE 9 bus system with 20% PV penetration.