We deliver critical infrastructure and transmission services, connecting Queenslanders to a world-class energy future.
Our transmission network extends 1,700km from north of Cairns to the New South Wales border, and comprises 15,559 circuit kilometres of transmission lines and 154 substations.
What is a substation?
Substations manage the flow and voltage levels of electricity around the transmission network and help keep the network stable to provide a reliable electricity supply.
Electricity enters and leaves the substation via transmission lines – electricity is not generated at a substation. Generators or large industrial customers can link to the transmission network by connecting to a substation.
Powerlink’s substations typically convert electricity from high voltages to lower voltages so it can be delivered to the distribution networks operated by Energex and Ergon Energy for delivery to residential customers and businesses. Substations also convert electricity to higher voltages to be efficiently transported across large distances.
Substation equipment
A substation contains electrical equipment as well as buildings to house equipment for monitoring and control of the network. Equipment includes:
transformers to convert electricity to a higher or lower voltage
switches to interrupt the flow of electricity or disconnect parts of the substation for safe maintenance work
instruments to measure the flow of electricity for metering and to protect equipment
busbars to move electricity around the substation.
What is a transmission line?
A transmission line is a powerline which is capable of carrying large amounts of electricity at high voltages. In Queensland, transmission lines generally carry electricity at 132 kilovolts, 275 kilovolts or 330 kilovolts (kV).
Transmission lines are larger and taller than the everyday distribution powerlines which deliver electricity to your home and business.
Transmission structures
Transmission lines are normally built on tall steel towers or concrete and steel poles.
The distance between structures, structure height, footprint and design vary to accommodate the number of conductors, voltage carried, and the local topography, land use and environment.
Powerlink uses a range of structures to maintain a safe electrical clearance between the conductors and the ground below. When topography is considered it directly influences the tower height i.e. either increasing or decreasing depending on network requirements for a specific area.
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ENERGY EXPLAINERS
QUEENSLAND'S TRANSMISSION NETWORK
THE ELECTRICITY SUPPLY CHAIN
system strength
System strength is the transmission network’s ability to maintain stable voltage both during normal operation and when there is a disturbance, like a sudden change in generation or load, or an unexpected electrical fault.
The Australian Energy Market Operator (AEMO) determines the standards for system strength. As Queensland’s System Strength Service Provider, Powerlink must deliver what is needed to meet those minimum standards.
Queensland’s electricity has historically been generated by large coal-fired, gas-fired and hydroelectric power stations. These power stations use spinning generators to produce energy and stabilise the electricity network, providing system strength.
As the electricity generation mix in Queensland evolves, including the eventual retirement of coal-fired generation, system strength will need to be provided by a range of other sources, including synchronous condensers.
