Semi scheduled generators - Proposed rule changes

Date initiated: 
24 June 2020


The AER has proposed a change in the energy rules that stops semi scheduled generators from turning off without instruction from the market operator. The AER has requested the Australian Energy Market Commission (AEMC) consider the rule change be fast tracked, due to the extensive consultation undertaken prior to submitting the rule change.

The rule change follows a request from the Council of Australian Governments’ Energy Council (COAG EC) in March 2020 to develop rule changes for semi scheduled generators to improve their functioning within the National Electricity Market (NEM).

The AEMC will now consider the proposed rule change.


The AER released an issues paper on June 24 2020. The paper presented analysis on the COAG EC request for the AER to develop two rule change proposals to support system security in the National Electricity Market (NEM). Specifically, the requests from COAG EC were:

  • That semi scheduled generators be obligated to follow their dispatch targets in a similar manner to scheduled generators; and
  • Semi scheduled generators be required to continually inform the AEMO of any restrictions on their available capacity due to physical factors, ambient weather conditions and their market intentions.

Key points of the issue paper included:

  • Analysis and evidence that some semi scheduled generators have begun to deviate from their instructed output and how this behaviour has been increasing over time.
  • The impact this behaviour is having on the NEM now, and potentially into the future.
  • The benefits of having greater certainty of the output of semi scheduled generation

The issues paper also presented potential options for the rule change(s) to address the request.

On 24 August 2020 an update to the proposed rule change which provided stakeholders with information on a change to the preferred approach was released. 

Public consultation

A webex workshop was held on Thursday 2 July 2020.

Submissions on the issues paper were due by 24 July 2020.

Submissions on the update paper were due on 1 September 2020.