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Available Transfer Capability is a measure of the transfer capability remaining in the physical transmission network for further commercial activity over and above committed uses
Available Energy Capability- Is the amount of available energy on a specified transmission reservation
Counterflow Energy Schedule – Energy schedules flowing in the opposite direction of a path
Firm Capacity – The amount of transmission available after a single contingency
Firm Sales – Total Firm sales on the Path
Network Integrated Transmission Services – A transmission service that allows network customers to efficiently and economically utilized their network resources to service their network load located in the TP’s BA.
Point of Delivery – point at which energy is delivered by the transmission system
Point of Receipt – point at which energy is received by the transmission system
Purchase/Selling Entity – an entity that purchased or sells energy
Transmission Reliability Margin – The amount of transmission transfer capability necessary to ensure that the interconnected transmission network is secure under the reasonable range of uncertainties in system conditions.
Total Transfer Capability: the amount of electric power that can be transferred over the interconnected transmission network in a reliable manner while meeting all of a specific set of defined pre –and post contingency system conditions
Operationg Transfer Capability: The maximum value of the most critical system operating parameters which meets (a) pre-contingency criteria as determined by equipment loading capability and acceptable voltage conditions, (b) transient performance criteria, or (c) post – contingency loading and voltage criteria
BC Hydro has interconnections with both Alberta and the USA referred to by WECC as Paths. What are the Path names that connect with the BC Hydro to Alberta and the US and what transmission lines make up the Paths? (4 Marks)
- Path 1: BC – Alberta
- Tx Lines: 5L94 1L274 1L275Path
- 3: BC – US
- Tx Lines: 5L51/52 2L112 L71
3. Fully Explain TRMu: (3 Marks)
Transmission Reliability Margin unreleased: Is the amount of transmission set aside that is not available to purchase to account for unforeseen events in load forecasting. This helps maintain that the OTC limit is not violated.
Fully explain Secondary Transmission Service. (3 Marks
Transmission that is reserved for customers who own Firm Tx and wish to redirect to a different POD/POR on a non-Firm basis. Secondary Transmission Service is the lowest priority. If the secondary Tx is cut, the customer will not lose their firm transmission
What is the start/stop time and duration of a normal hourly ramp? (2 Marks)
XX:50 Ramp StartXX:10 Ramp Stop
List the Classes of Tx from highest to lowest and the Priorities within each class (8 Marks)
- 0NX – Net Hour Market
- 1NS – Non Firm Secondary
- 2NH – Non Firm Hourly
- 6NN – Network Economy Type 2
- 3ND – Non Firm Daily
- 4NW – Non Firm Weekly5NM – Non Firm Monthly
- 6NN – Network Economy Type 1
- 7F – Conditional Firm
- 7F – Firm
What is Network Economy transmission and who is eligible for this service? (4 Marks)
Transmission Reserved for Customers with a NITS contract that allows them to integrate, economically dispatch and regulate it’s current and planned network resources to serve it’s native load inside the BA. NE is considered higher priority than Non-Firm Tx
Why is XX:00 a significant time for tx scheduling? (1 Mark)
BA’s will calculate TTC on an hourly basis. At this time the schedules are compared and the lower value of TTC will be used for that purpose.
In pre-schedule, PSE ‘A’ has purchased 100MW of 7F transmission for HE10. By 08:00 the day of transmission reservations, the PSE has only scheduled 25MW of energy on the service. What would happen to the 75 MW of transmission that has not had energy scheduled on it.
At XX:10 Unused Firm Tx is added to the Network Economy ATC, Non Firm ATC and secondary ATC for offering on OASIS.
For eTags, why is XX:40 significant? (1 mark)
BC Hydro processes eTags according to the NAESB Interchange Timing requirements for WECC. eTags will be processed (APPROVED or DENIED) automatically up to 20 minutes (xx:40) before the Start Time. Submission of eTags after xx:40 will be treated as Late.
What is blanket functionality? (4 Marks)
· Option for PSE to enter in a Blanked OASIS ID that specifies TC, path, POR/POD and transmission type, the BC Hydro scheduling system will retrieve all Confirmed and active TSR’s that match the parameters.
· TSRs used as part of a blanket approach will be of the same priority code type.
· Blanket functionality may include Horizontal and vertical stacking where multiple TSR’s are used to achieve a certain level of capacity or a certain capacity over time.
Fully explain an Interruptible schedule. Why is it important that interruptible schedules are correctly identified? (5 Marks)
A non-firm energy schedule that the PSE has specified may be interrupted for any reason including reliability.
The Schedule may be interrupted by the Source BA for any reason followed by a notification through eTag.
Export schedules may be interrupted by BCH if the PSE delivering the export fails to meet CRO with BCH.
The Sink BA must provide 100% of the CRO
Interruptible schedules should be the first to be curtailed for reliability reasons.
With respect to curtailments when do we curtail?
Curtailment of transmission service occurs when an emergency or other unforeseen condition and/or commercial activity threatens to impair or degrade the reliability of the transmission system.
- Economic Interruption:
- - When a valid higher class TSR interrupts a lower TSR.
- · When Non Firm Tx is purchased on Firm Tx and the Firm Tx owner schedules on their rights.
- A loss of transmission:
- - If transmission is cut, associated energy must also be cut to avoid negative AEC.
- - Infringement on the SL: A reliability limit is placed on the TSR. Energy associated with the TSR is curtailed until the energy schedule is equal to or lower than the SL.
- Loss of energy:
- - To reserve or restore CRO and SRO
How do we curtail?
- At XX:40 if there is an infringement on the SL for the next scheduling hour or a condition that degrades the reliability of the system and causes on infringement on the SL then Reliability Limits will be placed on the appropriate TSRs which may lead to curtailment of energy.
- Each TSR has a NERC curtailment priority code that will determine the order of any reliability limits placed. If two non firm TSRs have the same priority code then the reliability limits will be based upon LIFO while firm TSRs will have reliability limits based on pro-rata.
- Reliability limits will be assigned until the infringement on upon the SO is resolved
- Energy schedules are curtailed by a priority of Interuptible/RecallableNormal/ UninterruptibleReserves/CapacityDyanamic.
MODS or WebTag May be used to individually curtail.