Storage-Conscious Dispatch Strategy for Hybrid Power Plants

Hybrid power plants (HPPs) power plants contribute toward the goal of decarbonization and achieving net-zero emissions by providing more stable and reliable energy output compared to traditional single-source generation plants. HPPs can be not only a combination of multiple types of generation technologies, but also different types of energy storage technologies.

This aspect is deeply rooted in the unique and diverse nature of storage technologies, each featuring its own set of persuasive advantages and notable disadvantages.

These characteristics may include energy density, power density, ramp rate, and life cycle, each presenting trade-offs with one another. Supercapacitors and flywheels are known for their quick cycling and low energy density, yet they provide extended longevity in terms of cycles. On the other hand, chemical batteries have a medium cycle paired with medium to high energy densities, but they suffer from a limited lifespan in terms of cycles. Compressed air storage systems are noted for having a prolonged cycle duration, low energy density, and moderate cycle life. The economic viability of battery storage systems is hindered by rapid degradation and a restricted lifecycle. The cost of replacing battery energy storage systems can substantially reduce potential profits.

This study aims to present a novel HPP controller (HPPC) to dispatch the active power within wind turbines as the variable renewable energy resources, a high-power storage technology (HPST) such as Supercapacitor, and a high-energy storage technology (HEST) such as Lithium-ion Battery. The dynamical control includes different functionalities such as power smoothing mode and constant setpoint following mode. The study includes different methods of power smoothing.

The core concept behind this power allocation is that the HPST is responsible for managing fast-fluctuating power setpoints, while the HEST manages slowly changing setpoints. Meanwhile, the WTs operate in MPPT mode except when curtailment is necessary. To achieve this objective, the setpoint of the HEST will be determined in accordance with the power delivery state of the HPST.

The simulation outcomes demonstrate that this approach can prolong the lifespan of HEST by mitigating harsh usage. Additionally, it addresses the drawback of HPST's short cycle duration while still meeting the overall goals of HPPC.