Development of a Plant Controller for Grid-Connected Hybrid Renewable Power Plants with Enhanced Market Participation Strategies

Renewable energies have taken a decisive role on the path toward decarbonizing the electrical system to mitigate the effects of climate change. However, their massive integration poses several challenges, mainly linked to their intermittent generation and lack of synchronous inertia, which require installing additional capacity to ensure covering all the demand. As a result, in the near future, renewable power plants will have to deal with curtailments, as well as additional requirements to support the grid stability.

Hybrid power plants (HyPPs) combining different renewable generation and storage technologies are able to cope with these challenges and are becoming a reality in countries with high renewable penetration. If correctly sized and controlled, HyPPs can provide a more reliable power production, offer grid ancillary services and reduce the curtailment by storing part of the energy when it is not demanded. Nevertheless, the combination of different technologies in HyPPs presents several operational challenges.

This PhD thesis aims to investigate on the high level controllers needed to operate grid-connected HyPPs and maximize their profitability. More specifically, the thesis focuses on the development of energy and power management system (EMS and PMS) control levels to optimally operate HyPPs consisting of wind, solar PV and BESSs.

The first research line of the thesis deals with an EMS to operate optimally in different electricity markets while ensuring a cost-effective use of the BESS. The contributions include the combination of classical and metaheuristic optimization methods, the study of forecasting error effects in the participation on intraday electricity markets, and the provision of automatic Frequency Restoration Reserve (aFRR) services to the grid. In addition, the upcoming new aFRR market scenarios and the current electricity market crisis effects are deeply studied from a techno-economic perspective.

The second research line copes with the development and validation of a HyPP PMS to dispatch the real-time power setpoints for each subplant. The work includes several strategies to translate the energy setpoints generated by the EMS into active and reactive power setpoints, and the control algorithms required to fulfill with the Spanish Grid Code. Advanced dispatch strategies are presented to deal with different grid events, and the controller is validated based on the official tests required by the Spanish Transmission System Operator (TSO). To do so, after an offline design and tuning process, the PMS is implemented on an industrial controller and real-time hardware in the loop (HIL) simulations are performed to account for all the communication effects.

The last research line is on the development of a method to size BESSs inside HyPPs. The method is based on running the EMS iteratively to simulate the optimal operation of the plant. Then, different market conditions and technical constraints are applied to select the most appropriate sizing for the studied HyPP.