New Zealand Gazette – 2001 – No. 163

Page 4002

✨ Energy Reliability Statistics



NEW ZEALAND GAZETTE

No. 163

Part 6

Reliability Performance Measures to be Disclosed by Transpower

(Disclosure Under Regulation 22)

  1. **Total number of unplanned interruptions***
    Resulting from 55 loss of supply incidents in 2000/01

    2000/01 1999/00 1998/99 1997/98
    102 62 110 103

  2. Electricity customer interruptions in system minutes... **

    | | 2000/01 | 1999/00 | 1998/99 | 1997/98 |
    |-----------|--------|--------|--------|
    | Total | 12.5 | 4.9 | 9.7 | 5.1 |
    | Planned | 0.9 | 2.8 | 2.7 | 2.1 |
    | Unplanned | 11.6 | 2.1 | 7.1 | 2.9 |

  3. Underlying electricity customer interruptions in system minutes... *
    Underlying interruptions are those interruptions of 1 system minute or less duration*

    | | 2000/01 | 1999/00 | 1998/99 | 1997/98 |
    |-----------|--------|--------|--------|
    | Total | 4.0 | 4.9 | 7.3 | 5.1 |
    | Planned | 0.9 | 2.8 | 1.7 | 2.1 |
    | Unplanned | 3.1 | - | 5.6 | 2.9 |

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

    2000/01 1999/00 1998/99 1997/98
    99.9963 99.9986 99.9972 99.9985

  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.

    2000/01 1999/00 1998/99 1997/98
    - - - -

  6. Uneconomic generation due to HVDC system unavailability
    %

    2000/01 1999/00 1998/99 1997/98
    - - - -

  7. Uneconomic generation due to unplanned transmission system unavailability
    %

    2000/01 1999/00 1998/99 1997/98
    - - - -

  8. Planned interruption restoration performance
    %

    2000/01 1999/00 1998/99 1997/98
    89.5 100 94.4 90.5

  9. Unplanned interruption response
    %

    2000/01 1999/00 1998/99 1997/98
    100 100 100 98.1

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.

  • 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.




Online Sources for this page:

VUW Te Waharoa — PDF NZ Gazette 2001, No 163


Gazette.govt.nz — PDF NZ Gazette 2001, No 163




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🏭 Reliability Performance Measures for Transpower (continued from previous page)

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