1. Imbalance Price Modifications
TSC Modifications – Extraordinary Meeting 86
Dave Carroll, Trading Operations, SEMO
6th September 2018

2. Background
Imbalance price calculated every 5mins, from which the 30 min Imbalance Settlement Price is derived
Market Backup price is calculated after each Gate Closure for the Imbalance Settlement Period that most recently closed
Highly automated due to continuous trading

3. Background @ 20:10 the Backup Imbalance Price for 21:30 is calculated
20:00
20:05
20:10
20:15
20:20
20:25
20:30
20:35
20:40
20:45
20:50
20:55
21:00
21:05
21:10
21:15
21:20
21:25
21:30
21:35
21:40
21:45
21:50
21:55
5 min
30 min
Backup 50 48 52 55
@ 20:10 the Backup Imbalance Price for 21:30 is calculated

4. Background
20:00
20:05
20:10
20:15
20:20
20:25
20:30
20:35
20:40
20:45
20:50
20:55
21:00
21:05
21:10
21:15
21:20
21:25
21:30
21:35
21:40
21:45
21:50
21:55
5 min 50 46 55 57 60 47 48 52
30 min
Backup 53
@ 21:00 the 5 minute Imbalance Price for 20:35 – 20:40 is calculated

5. Background
20:00
20:05
20:10
20:15
20:20
20:25
20:30
20:35
20:40
20:45
20:50
20:55
21:00
21:05
21:10
21:15
21:20
21:25
21:30
21:35
21:40
21:45
21:50
21:55
5 min 50 46 55 57 60 47 48 52
30 min
52.5
Backup 53
@ 21:00 the 30 minute average Imbalance Price from 20:00 – 20:30 is calculated

6. Current Process Imbalance Settlement Price Market Backup Price
Market Management System (MMS)
Imbalance Settlement Price
Market Backup Price
Most Recent Imbalance Price
Not Available
Not Available

7. Rationale for Modification
Experience from SEM go-live and from market trial
Unscheduled outages not specifically accounted for in the code (MOD_30_18)
Scheduled outages may be more frequent and longer in duration during start of market (MOD_31_18)
Need to improve transparency of what the Imbalance Price is at all times for Market Participants

8. Proposal Each day get the ex-ante price from the Day Ahead Market
Convert this from an hourly to half hourly price
Publish “backup to PMBU” prices on website
If the Imbalance Settlement Price and Market Backup Price are not available 30 minutes after the end of the relevant Imbalance Settlement Period, then the “Backup to PMBU” price is effective and will be used in settlement
Issue Market Message to participants

9. Pre-published Backup Imbalance Price based on DAM
Proposed Process
Imbalance Settlement Price
Market Backup Price
Pre-published Backup Imbalance Price based on DAM
Most Recent Imbalance Price
Market Management System (MMS)
Not Available
Not Available
Not Available
Not Available
Not Available

10. Justification
Improves resilience as a further backup Imbalance Price will be available before a previous Imbalance Price (which may be totally unreflective) needs to be used
The “Backup to PMBU” price based on the DAM will be more reflective of prevailing prices where most trading occurs
Market Participants will always be aware of what price is being used 30 mins after an Imbalance Settlement Period

11. Discussion
Any Questions?