Battery Storage Participation in Reactive and Proactive Distribution-Level Flexibility Markets

Modern power systems are experiencing a paradigm shift toward distributed energy resources (DERs) and an accelerated penetration of the renewable energy sources (RES). Intermittent and distributed RES pose serious challenges to the system operators in terms of the increased flexibility requirements. Besides the technical flexibility, achieved through, e.g. storage devices, the market flexibility is also important as it enables rewarding the flexibility providers at an appropriate time-scale. Distribution-level flexibility market (DLFM) is considered as one of the viable solutions to successfully integrate high shares of RES and promote an active role of electricity consumers. This paper defines and analyzes two DLFM setups where a distributed flexibility source, i.e. battery energy storage, can bid in addition to the existing markets (day-ahead, intraday and balancing). The main difference between the observed DLFM setups is their clearing time. One clears before the day-ahead market, while the other one in between the day-ahead and the intraday markets. Uncertainty in the intraday market is addressed using robust optimization, while stochastic optimization deals with the DLFMs and the day-ahead market. This results in a four-stage model, which is reduced to a three-stage model because the balancing market follows directly from the previous market position realizations. In the presented case study, we analyze how different market clearing sequences affect both the player providing flexibility and the market operator procuring it.