Wind-plus-battery system optimisation for stacking of frequency response and black start services in the UK

The energy storage-friendly reforms of the ancillary service markets in the UK have heightened interest in co-locating battery energy storage systems (BESSs) with renewable power plants for the stacking of multiple revenue streams. This paper develops a modelling framework to simulate the operation of a wind farm (WF) and BESS co-location system where the BESS uses the existing connection point to deliver frequency responses (FRs) to the AC grid while sustaining a minimum energy level to assist the WF in supplying demand blocks in black start (BS) events. The BESS capacity and operating strategies are optimised to maximise the final net present value of the co-location project based on the UK perspective, addressing the trade-off between the BESS costs and the availability performance of FR and BS services. The modelling framework is demonstrated based on a particular transmission-connected WF in the UK combined with a weekly auctioned FR product, i.e., Dynamic Low High (DLH). The optimisation results are compared between the DLH-only provision and the stacking of BS and DLH, and discussed around the techno-economic feasibility of co-location projects, in particular, the BESS energy management and the minimum possible availability prices for DLH and BS services.