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Development of Grid Reliability Standards

Under clauses 12.49 - 12.75 (sub-part 4) of the Code, the Authority is required to consider and determine the grid reliability standards.

The purpose of the grid reliability standards, as set out in Part 12, is to provide a basis for the Authority to publish statements of opportunities, for Transpower for prepare grid upgrade plans, and for other parties to appraise opportunities for transmission investments and transmission alternatives.

Work carried out between 15 September 2003 and 31 October 2010 was the responsibility of the Electricity Commission.

On 1 April 2005, the Commission made a recommendation to the Minister of Energy and Resources for the inclusion of the Grid Reliability Standards (GRS) as a schedule to section III of part F. This recommendation was formally notified in the Gazette on 7 April 2005.

The Commission's recommendation was agreed to by the Minister and the GRS and the associated rule amendments were formally notified in the Gazette on 14 April 2005.

The GRS came into force on 13 May 2005.

Core grid determination

In developing the GRS, the Commission signalled its commitment to pursuing an economic approach to grid reliability, strongly linking the GRS with the application of the grid investment test (GIT) . However, the Commission acknowledged that there was concern amongst a number of stakeholders about the uncertainties and implementation issues associated with moving to such an approach. A two-limb grid reliability standard was therefore developed, consisting of an economic standard for the whole grid, underpinned by a “safety net” of an N-1 standard for contingencies on the core grid.

As part of the GRS drafting package, a set of rules relating to the determination of the core grid was incorporated in part F. In essence, the Commission was required to develop a draft core grid determination, invite submissions on this, then make a final core grid determination recommendation to the Minister, having considered the submissions received. Once approved, the core grid was appended as a schedule to part F of the Rules.

Determining the core grid was an important step in the process of completing the GRS framework. Once the core grid was determined, the capability of the grid to meet the GRS could be fully assessed.

Core grid determination recommended to Minister of Energy

Due to an administrative error, the recommendation the Commission made to the Minister on 12 December 2005 contained an incorrect version of Table 1 in the new Schedule F3A - Core Grid Determination. This error was repeated in Appendix 2 of the recommendation (Assessment under section 172F(1) of the Electricity Act 1992), and in the Explanatory Paper published on 22 December 2005.

Section 13 of the Interpretation Act 1999 provided that a statutory power may be exercised to correct an error in a previous exercise of the power.

The Commission made a recommendation to the Minister on 16 January 2006 that the gazette notice of 22 December 2005, making the Electricity Governance Amendment Rules (No. 33) 2005, be amended, and that the date on which those rules come into force be extended to 16 February 2006.

The Commission made a recommendation to the Minister on 12 December 2005 and the key documents relating to that recommendation are as follows:

Revised draft core grid determination

The Commission published a revised draft core grid determination for consultation on 21 October 2005. The closing date for submissions was Monday 14 November 2005 and 10 submissions were received.

Core grid determination discussion session

On 23 September 2005, the Commission held a discussion session on the core grid determination. all submitters on the June 2005 draft core grid determination were invited to this session.

Presentations

Core grid determination comments period

On 24 August 2005, the Commission published the core grid determination that the Commission proposed to recommend to the Minister. The Commission also published the accompanying explanatory material which sets out the Commission's review of submissions it received on the draft core grid determination.

The Commission gave interested parties a short period (from 24 - 29 August 2005) in which to provide any comments on the drafting of the core grid determination.

Comments received on core grid drafting:

Draft core grid determination consultation

On 24 June 2005, the Commission published its draft core grid determination for consultation. The submission expiry date was 20 July 2005. 17 submissions were received.

Grid reliability standards

Grid reliability standards (GRS) recommended to Minister of Energy

The key documents relating to the Commission's recommendation to the Minister regarding the GRS can be found below:

GRS drafting comments period

On 24 March 2005 the Commission published the GRS that the Commission proposed to recommend to the Minister and the accompanying explanatory material which sets out the Commission's review of submissions it received on the draft GRS.

The Commission decided to recommend the alternate proposal package.

The Commission gave interested parties a short period in which to provide comments on the drafting amendments made from the consultation version of the GRS. This period closed on 29 March 2005 and comments were received from five parties.

  • Drafting comments received

Draft GRS consultation

The Commission published its draft grid reliability standards for consultation pursuant to rule 4.5 of section III of part F on 17 December 2004.

The submission expiry date was 9 February 2005 and 12 submissions were received.

External Peer Review of GRS

In 2008, the Commission sought an external expert view of its application of the GRS and a comment on overseas grid planning trends.

The Commission engaged Professor Goran Strbac, Chair in Electrical Energy Systems at Imperial College London, and his colleague Dr Predrag Djapic to review the GRS. Both Authors have extensive work experience advising the United Kingdom Government, the UK Regulator and Industry on network security, investment, access and pricing matters.

Recently, Professor Strbac and Dr Djapic have worked on the development of cost benefit methodologies on which the new Great Britain (GB) distribution network planning standards were based, and also on the first GB transmission network design standards for offshore networks. They are currently directly involved in the Fundamental Review of GB Transmission Network Security Standards which will include examination of reliability benefits of network reinforcements.

External Peer Review of Grid Reliability Standards in New Zealand: Summary Report

This page is related to: Transmission.

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