Bidding
Flexibility is a deviation from the baseline, which we've learned about in the previous section. As a next step, we need to learn how to report these deviations, which is done using bids.
Components​
When submitting a bid, a couple of key components are needed:
- A time frame
- One or more power values
- (Optional) A price
- (Optional) Power type
- (Optional) An expiration date
Let's have a closer look at each of these components.
Required​
Timing​
Bids are always valid for a certain time frame, and therefore contain a start and end time. By making a bid, you are essentially saying: "The resource can provide flexibility in this time window".
The timing for a bid has the following constraints:
- They should always be a perfect quarter-hour (e.g.
14:00:00 - 14:15:00). - The end date of the bid must be at least 30 seconds in the future.
You can submit bids for the current quarter-hour, as long as there's more than 30 seconds left in it.
Example: You can submit a bid at 14:12:00 for the time period 14:00:00 - 14:15:00,
as long as you can deliver on that bid.
See the bid acceptance guide for more information.
You can only bid once with each resource for the same time window.
Power​
The power values are the most important part of the bid.
They represent alternative power levels (setpoints) that the resource can deliver. The difference between the baseline and the power values indicates the flexible potential of the resource.
This is reported as a either a single power level, or a range of power levels (a bid curve). See the section on bid curves for a more details.
The default unit for power is kW, which indicates active power.
You can also make bids for reactive power, in kVAR. See power type for more.
Optional​
Price​
The price is an optional component of the bid, and represents the minimum price at which the resource is willing to provide flexibility.
This price is used to ensure that the resource is only activated when the price is right, and to prevent the resource from being activated in economically uninteresting situations, for example:
- Take into account the cost of providing flexibility.
- Shifting loads might mean there's a higher cost of energy later on.
- Curtailing solar might only be interesting when the price received is more than the injection tariff.
- ...
- Taking additional grid costs into account.
- Taking operational costs into account.
A battery might only want to export power when the price received is higher than the usual injection tariff, ensuring the retention of valuable stored energy.
A thermostat might only want to increase its heating processes when the price covers the extra expense on grid costs.
Power type​
The power type indicates the type of power the site or resource can provide.
This can be either active power (kW) or reactive power (kVAR).
Any power values (baseline or flexible) reported in the bid,
should be in the same unit as the power type.
More information on the difference can be found here.
When leaving the power type empty, it defaults to active power.
Expiration​
You can expire a bid at a certain time, which can be useful if you need sufficient time to prepare for the activation.
Bids will be accepted at least 30 seconds before your reported expiration time,
allowing for a sufficient time window of activation.
Similarly, you can't update or cancel bids after this safety margin.
Bids will be reported as expired 30 seconds before their actual expiresAt time.
Bid curves​
Bid curves are a way to provide more detailed information about the flexibility potential of a resource.
Based on the power type of the bid,
the unit of the bid points is either kW (active, default) or kVAR (reactive).
When not providing any pricing information for a bid curve point, a price of zero is assumed. This essentially means that there is no cost for activating this bid point.
Single point​
The easiest way to perform a bid is providing a single power level, at an optional price.
Examples
To understand a bit better the use case for single point bids, check out the examples below:
Multiple points​
A lot of resources can typically provide flexibility at multiple power levels, potentially with different signs (consumption vs. production).
By providing multiple points in the bid, you can tell the platform all the possible power levels (setpoints) that the resource can provide.
Examples
The following practical examples show how multiple point bids can be used:
The Powernaut platform allows a maximum of 100 points per bid curve.
Acceptance​
When a bid is accepted, the resource is requested to act on its flexibility, which is called an "activation".
In the next section, we'll see how that works.