Why build an Underground Transmission Line? What are the reasons for building an underground
A typical example is a transmission line from South Pine to Sandgate that was built as an underground line by Powerlink.
To meet the growing demand for electricity in the north-eastern Brisbane areas, Powerlink constructed a new 275kV high voltage transmission line to reinforce electricity supply between its South Pine Substation at Brendale and ENERGEX’s Sandgate substation near Deagon. The
majority of the new power-line was built beside an existing ENERGEX power-line, which runs between these two substations.
The new power-line will meet the growing demand for electricity in and around the north-eastern Brisbane areas of Boondall, Bracken Ridge, Brighton, Shorncliffe, Taigum, Sandgate, Deagon, Bridgeman Downs and Bald Hills.
A short section of the 9km power-line (about 2km) was placed underground where there was insufficient room for another overhead power-line.
Anti-Islanding Protection of Large, Grid Connected Photo-Voltaic (PV) Systems
The Energex supply network in Brisbane requires grid connected, photo-voltaic units above a certain size, to be capable of two basic functions:
1. Safe and satisfactory operation in parallel with the grid
2. Effective and swift automatic disconnection from the grid on the occurrence of either a generating unit fault or a supply network fault
An island external to the customer’s connection point, supplied from the customer, must not be created during an outage of the supply network.
Therefore Energex has requirements for anti-islanding protection.