8.9 Other issues reported by Australian industries
The biggest issue currently being faced by many Australian utilities is over-voltage due to a large number of small-scale rooftop solar installations. There may be a need for dynamic voltage control at more localised levels and more sophisticated voltage regulation than what currently exists in order to solve the issue of network over-voltage. There was a significant amount of discussion over the AS4777 standard and the need for this standard to be revised in order to utilise solar inverters for the purpose of voltage regulation. Currently, these inverters simply turn off when the voltage or frequency limits are exceeded. Revisions of the standard that will allow inverters to perform the following operations, i.e. ‘smart’ or ‘intelligent’ inverters, were discussed by power system operators:
- operation in voltage regulation mode
- possibility of remote control/configuration of the inverters
- power factor/reactive power control
- emulation of spinning reserve via capacitors or storage.
The frequency limits in thewere changed to 46 Hz (lower) and 54 Hz (upper). This was done to avoid low-frequency tripping of inverters during system frequency drop events (i.e. frequency briefly dropping by several Hz during central generation events).
A workshop participant reported that Alice Springs has a 12% penetration level of solar power at times and is experiencing(Var) generation issues. There is a high usage of air-conditioning during the daytime in the area, which is well correlated with the daily solar profile. 70% of the 28,000 people in Alice Springs changed their power usage behaviour and shifted their load usage to off-peak times with the introduction of the Time-of-Use (TOU) pricing.