New Zealand Gazette – 2004 – No. 171

Page 4290

✨ Reliability Performance Measures



4290

NEW ZEALAND GAZETTE, No. 171

22 DECEMBER 2004

Part 6

Reliability Performance Measures to be Disclosed by Transpower

(Disclosure Under Requirement 21)

  1. Total number of unplanned interruptions* 75 72 110 106
    Resulting from 45 loss of supply incidents in 2003/04

  2. Electricity customer interruptions in system minutes**
    Planned 5.3 6.3 6.1 12.7
    Unplanned 1.7 3.6 3.2 0.0
    3.6 2.6 4.8 11.8

  3. Underlying electricity customer interruptions in system minutes **
    Underlying interruptions are those interruptions of 1 system minute or less duration
    Planned 1.7 3.6 3.2 0.9
    Unplanned 3.6 2.6 4.9 3.1
    % 99.9985 99.9982 99.9976 99.9963

  4. Average supply reliability
    Measured by the energy supplied divided by the sum of the energy supplied and not supplied

  5. Uneconomic generation due to planned and unplanned transmission system unavailability %
    Uneconomic generation relates to the amount of electricity generated from any source other than the most economic source.

  6. Uneconomic generation due to HVDC system unavailability % - - - -

  7. Uneconomic generation due to unplanned transmission system unavailability % - - - -

  8. Planned interruption restoration performance % 71.0 61.3 81.8 84.5

  9. Unplanned interruption response % 98.7 100 100 100

The information compiled using estimated information includes Part 6 sections 2,3 and 4. The methodology used to calculate the estimated information is documented and available from Transpower upon request.

Uneconomic generation (Part 6 sections 5, 6 and 7) is not relevant in the market environment because scheduling is now based on offered price, not economic cost. In the market, ‘offers to generate’ are made after taking constraints into account and it is not possible to predict what a generator would have offered if the constraint was not present. As a result data is not available to allow a calculation and a null entry has been returned.

The reliability performance measures given in Part 6 do not include the performance of the 34km of circuit leased to other parties because Transpower does not collect operational data for these assets.

  • Where two supply voltages, or two customers at the same station are both interrupted this is counted as two interruptions.

** Any minor differences between the total and the sum of planned and unplanned are due to rounding.
System minutes of interruptions are not counted if energy is made up by backfeed from another point of supply or by embedded generation within a customer’s network.



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Online Sources for this page:

VUW Te Waharoa — PDF NZ Gazette 2004, No 171


Gazette.govt.nz — PDF NZ Gazette 2004, No 171




✨ LLM interpretation of page content

🏭 Certificate of Financial Statements and Performance Measures for Transpower New Zealand Limited (continued from previous page)

🏭 Trade, Customs & Industry
Reliability Performance, Electricity, Transpower, Interruptions, Supply