Rule Changes: Open

Managing power system fault levels

Reference:
ERC0211
Stage:
Publication of Draft Determination
Proponents:
South Australian Minister for Mineral Resources and Energy
Project Leader:
Julian Eggleston
Date initiated:
08-Sep-2016
Overview

On 27 June 2017, the AEMC published a draft rule and draft determination on the Managing power system fault levels rule change request. The draft rule allocates responsibility for the management of power system fault levels, also known as system strength.

On 27 June 2017, the AEMC published a draft rule and draft determination on the Managing power system fault levels rule change request. The draft rule allocates responsibility for the management of power system fault levels, also known as system strength.

The Commission’s draft rule

The draft rule amends the National Electricity Rules (NER) to accommodate issues associated with reducing system strength. It does so by allocating responsibility for maintaining system strength in a manner that maintains system security, while providing appropriate incentives and efficiently allocating risk to the extent possible.

A level of system strength is required for generators to be able to meet their technical performance standards. If system strength is too low, it may result in generators being unable to remain connected to the power system.

The draft rule:

  • provides an enhanced framework that requires network service providers (NSPs) to maintain the system strength at generating system connection points above an agreed minimum level under a defined range of conditions
  • introduces a process for the generator (or market network service provider), the relevant NSP and the Australian Energy Market Operator (AEMO) to agree and register a minimum level of system strength during the connection process
  • introduces a requirement on new connecting generators to 'do no harm' to the minimum level of system strength being provided to any nearby generating system connection points
  • includes a transitional process for existing generators, the relevant NSPs and AEMO to agree the level of system strength that the relevant NSP will be obligated to maintain at the relevant connection points in its network, on an ongoing basis.

This draft determination forms part of the work program of the System security market frameworks review. This review supports the continuing transformation of the NEM by considering the regulatory frameworks that affect system security in the NEM, in particular, the management of frequency and of system strength in a power system with reduced levels of synchronous generation.

The Commission is seeking stakeholder feedback on this draft rule and draft determination. We invite stakeholders to provide written submissions by 8 August 2017.

Background

On 8 September 2016, the AEMC initiated the rule making process for the Managing power system fault levels rule change request submitted by the South Australian Minister for Mineral Resources and Energy.

The exit of large thermal synchronous generation, together with an increasing proportion of non-synchronous generation like wind and solar, has contributed to decreases in system strength in some areas of the power system.

A reduction in system strength in certain areas of the network may mean that generators are no longer able to meet their technical performance standards and may be unable to remain connected to the system at certain times. It may also lead to voltage instability and a reduction in the effectiveness of the protection systems used by network businesses, generators and large customers. If not addressed, these effects could lead to system instability and potential major supply interruptions

On 15 December 2016, the AEMC extended the period of time for making a draft determination on the rule change request until 29 June 2017. The AEMC determined that an extension was necessary due to the complexity of the issues raised in the rule change request. 

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AEMC Documents

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AEMC documents

Submissions

AEMC Documents

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