Ancillary Services¶
Services required by transmission/distribution system operator to enable them to maintain the integrity and stability of transmission/distribution system as well as power quality
Types¶
Reserve Types¶
| Reserve | |
|---|---|
| Primary | Shared among all system operators Daily day-ahead auctions Inflexible demand Needs upward & downward capacity Energy not considered (energy-neutral service ) |
| Secondary | Relieve primary reserve which has ben activated Restore any imbalance on interconnections Capacity purchases on monthly basis Combines symmetric upward & downward products Based on bilateral contracts (negotiated; non-public) Negative revenue in downward regulation case consists in buying back energy that is already sold through day-ahead market |
| Tertiary | Daily day-ahead auctions Varying demand Need upward & downward capacity Energy paid for at balancing price |
Activation Approaches¶
| Reactive | Corrective |  |
| Proactive | Preventive |  |
Quantify need for ancillary services¶
Depends on total uncertainty which is based on
- Supply-side uncertainty
- Demand-side uncertainty