Day-ahead dispatch model assumptions

We model a site to participate in different ancillary services throughout the day, as well as take wholesale trades.

Given wholesale power price and Dynamic Frequency Response prices (not shown above for simplicity), we optimize a 2h battery doing 2 cycles per day in this example.

Dynamic Regulation High is used to charge the battery

The system state of charge increases while it does DRH. By taking advantage of this 'free' energy, it can discharge for a wholesale price opportunity later on, as well as do some DC during the EFA blocks where the wholesale opportunities are not there.

We assume perfect foresight.

Numbers should be taken as such, and a capture rate applied to them.

Other assumptions

• We model a battery charging efficiency of 88%. This means that a 200 MWh battery would need to import 200/88% = 227 MWh to charge fully.
• Power stacked in different markets is kept within the battery's maximum charge and discharge limits.
• When volume is contracted in frequency response, we maintain sufficient headroom to provide that response at maximum volume for its maximum continuous time (see table below).
  • For example, a battery providing 1 MW DRH must be able to import 1 MW continuously for up to 1 hour.
• Contracted volume is constant in each EFA block.
• Only one frequency response market is allowed at any one time - eg. we don't combine Dynamic Containment High and Regulation Low.
• For symmetrical frequency response (High and Low), contracted volume is reduced according to that service's de-rating factor (see table below).
• Ramp rates: when providing frequency response services, we cannot ramp at a rate greater than 5% of the contracted volume - in the opposite direction.
  • This means a battery providing 1 MW DRH can increase its power export by 0.05 MW per minute.
• We model the throughput in each response service (see table below).