In recent years, utility-scale hybrid power plants (HPPs) have emerged as promising electricity generation resources by combining multiple generation technologies and storage capabilities. This paper presents a novel framework for optimizing the offering and operation of HPPs in the voluntary balancing market, specifically for providing regulating power as a balancing service. The proposed framework utilizes a two-level robust optimization approach, where the first level focuses on look-ahead offering and operation, and the second level handles real-time re-scheduling of generation. Uncertainties arising from wind power and regulating prices are considered as decision-independent uncertainties (DIU). Conversely, the decisions regarding regulating power offers influence the uncertainty associated with activated regulating volumes, leading to decision-dependent uncertainties (DDU). To tackle the model incorporating both DIU and DDU, this paper introduces a customized nested adaptive column and constraint generation (NAC&CG) algorithm that ensures global convergence. The case studies demonstrate the effectiveness of the proposed model in enabling HPPs to accurately track the activated regulating volumes, ensuring reliable provision of balancing service.

Since hybrid power plants (HPPs) play an intensive role in the energy supply balance of future energy systems, there is today an increased attention on co-located wind-battery HPPs both in industry and academia. However, the profitability of HPPs in sequential electricity markets to overcome initial investment costs has not been yet well examined, especially with respect to  balancing services provision. This article proposes a novel energy management system (EMS) for optimal participation of wind-battery HPPs in two sequential electricity markets, namely in spot market and balancing market. The methodology consists of three optimization models, which allow HPPs to achieve energy arbitrage, to provide balancing services, and to reduce real-time imbalance costs. Furthermore, the profitability of HPPs in future (2030) energy scenario is analyzed based on the new designed and developed EMS taking balancing service into account. The results of the overplanting case show that HPPs operated based on the proposed EMS achieve net present value 3.6 times as high as sole operation in spot market.