The purpose of the Hornsdale Wind Farm Stage 2 (HDWF2) Frequency Control Ancillary Services Trial was to determine and demonstrate the extent of the capability for wind farms of similar design and functionality to the HDWF2 and operating in similar conditions to the Hornsdale 2 WF to provide Frequency Control Ancillary Services to the National Electricity Market (NEM).
Report extract
The Hornsdale Wind Farm controller includes subset of controls and operating modes designed to assist the grid maintain frequency by responding to under and over frequency events. The controller responds to over frequency events by lowering power output and responds to under frequency events by increasing power output. This functionality of the controller was utilised for the HDWF2 trial.
The results from the HDWF2 trial show that wind farms of similar design and functionality to the HDWF2 and operating in similar conditions to the Hornsdale 2 WF can provide FCAS services in 6 of the 8 FCAS markets.
This is provided they can meet the relevant requirements of the MASS for registration and testing and operation/post event performance verification. HDWF2 trial did not meet the requirements of AEMO for the fast raise and lower (6 seconds) market: the wind farm does not currently provide adequate active power injection for fast raise (6 seconds) services in the event of a combined frequency and voltage ride through event.
To be able to increase power output in response to under frequency events the wind farm needs to be curtailed with the controller running a spinning reserve function. In this operating mode the wind farm will be generating less than the available power as wind energy is spilled. Due to difficulty in attaining the right conditions for the test schedule, as well as inexperience in co-optimising bidding the trial ran over the expected 48 hours to around 80 hours. This resulted in higher than expected lost production and revenue. In normal market conditions, the opportunities to sell FCAS services as a sustainable source of revenue for a windfarm may be limited. Providing FCAS is most economic under high FCAS prices conditions when it will effectively provide a hedge against high FCAS charges.
