Frequency Control Trials

In May 2018 tests were undertaken in Tasmania by Hydro Tasmania, AEMO and TAS Networks. The purpose of these tests was to assess the effect of changes to generator governor control settings, and to AEMO's AGC control system, on frequency control in the Tasmanian power system. These tests were undertaken while the Basslink HVDC interconnector between the mainland and Tasmania was out of service.

These tests demonstrated that reducing or removing the frequency control deadband on selected generators produced a very clear improvement in system frequency performance. Governor activity, or workload, was observed to increase as a result of these changes. The effect of changes to AEMO’s AGC system were less clear. In summary the Tasmanian trials demonstrated:

• generator control changes are required to improve frequency control under normal conditions.
• an increased workload on generator governors is necessary to provide the improved frequency control
• there is a connection between output of variable renewable generation, and deviation from normal operating frequency under normal conditions
• over the test periods chosen, AGC changes had a far smaller impact on frequency control than changes to generator control settings.

A similar trial involving changes to generator governor control systems on the mainland were proposed during 2019. However, given recent findings from AEMO’s 25 August 2018 incident report and the AEMC Frequency Frameworks review regarding the need to enhance NEM frequency control, AEMO will now develop an interim and longer term strategy to improve frequency performance in the NEM.

• Tasmanian Frequency Control Tests Summary Report (4.3 MB, pdf)