GB-specific assumptions for frequency response services and market participation
Dynamic Frequency Response
Since the launch of the Enduring Auction Capability (EAC), batteries can provide availability to different dynamic frequency response markets at the same time. For example, Dynamic Containment High and Dynamic Regulation Low can be combined.
We consider how many batteries are participating in each of the dynamic frequency response markets, and the total size of that market. This limits the average accepted volumes.
Service delivery rules
We respect the service delivery rules in Dynamic Frequency Response, as described by the Electricity System Operator in Great Britain:
- EFA block contracts: Frequency response contracts are of EFA block duration (4-hour periods), and their volume is constant within each block.
- State of charge requirements: The battery’s energy is kept within the allowed state of charge range, as per the rules of each service. This means keeping enough headroom (or footroom) in energy to provide the contracted response at maximum volume for its maximum continuous time.
- For example, a battery providing 1 MW Dynamic Regulation High must be able to import 1 MW continuously for up to 1 hour, at all times it is contracted in DRH.
- Symmetrical de-rating: For symmetrical frequency response (High and Low), contracted volume is reduced according to that service’s de-rating factor.
- Ramp rate constraints: Batteries participating in frequency response must respect ramp rates. We can’t ramp at a rate greater than 5% of the contracted volume in the opposite direction.
- This means a battery providing 1 MW DRH (high leads to charging) can increase its export power (i.e. discharge) by 0.05 MW per minute.
Service parameters
We model the throughput in each response service:
| Service | Hourly throughput (MWh per MW contracted) | Maximum continuous time (h) | Symmetrical de-rating |
|---|---|---|---|
| Dynamic Containment Low | -0.0056 | 0.25 | 0.95 |
| Dynamic Containment High | 0.0055 | 0.25 | 0.95 |
| Dynamic Moderation Low | -0.0264 | 0.5 | 0.9 |
| Dynamic Moderation High | 0.0244 | 0.5 | 0.9 |
| Dynamic Regulation Low | -0.1116 | 1 | 0.9 |
| Dynamic Regulation High | 0.1083 | 1 | 0.9 |
Revenue calibration
We assume perfect foresight of prices in our optimisation, but then calibrate revenues based on the Modo Benchmark data to make revenues readily usable in a business case. This accounts for real-world factors such as:
- Battery unavailability
- Imperfect foresight in actual trading
- No guarantee of winning frequency response contracts