How does electricity get to you? A guide to Western Australia’s energy grid

From your first coffee in the morning to the last light you switch off before you go to bed, our days are powered by electricity. Like most things which form part of our everyday routines, it’s easy not to give much thought to it. 

You might be familiar with ‘the grid’ - which is the term used to refer to the transmission and distribution network that carries electricity from power stations and generators to homes and businesses. 

The more you know about your electricity grid, the more you can make sense of how WA's energy future is changing - and the impact this has on your everyday habits and routines.

Here’s your walk-through guide to the electricity system which powers your days.

It all starts with the SWIS

Here in WA, our transmission and distribution networks are not connected to other networks in Australia.

There are two separate electricity grids in WA, the North-West Interconnected System (or the NWIS) covering the north-western part of WA and the South-West Interconnected System - or the SWIS which is the main grid and covers the south-western part of WA. Western Power owns and operates the transmission and distribution infrastructure within the SWIS. Synergy is a generator and retailer (or seller) of electricity in the SWIS. Western Power and Synergy are owned by the WA Government.

The Wholesale Electricity Market (or the WEM) is the name of the wholesale market for electricity in the SWIS. The Australian Energy Market Operator operates the WEM and ensures the security of electricity supply in the SWIS.

In the Eastern States, one of the world’s largest grids connects the electricity networks in Victoria, New South Wales, Queensland, the Australian Capital Territory, Tasmania and South Australia. This grid is known as the National Electricity Market (or the NEM).

Generation: From power plants to renewable energy

Electricity is generated then transported via the transmission and distribution networks to homes and businesses in the SWIS. Around 32% of electricity in the SWIS is produced by Synergy-owned generation assets with the remainder produced by other generators, some of whom Synergy purchases electricity from under long-term electricity supply contracts.

Electricity is generated from a number of different sources in the SWIS, including by coal and natural gas-fired generators, waste to energy plants (such as landfill gas), wind farms and solar farms. 

Installed rooftop solar is now the combined biggest single source of generation capacity in the SWIS during the middle of the day. With over 30% of homes in the SWIS having solar, rooftop PV systems can generate twice as much electricity as the largest power station on the system at certain times. However, WA still relies on fossil fuels (coal and gas), with large-scale wind and solar generation also playing important roles in our energy mix. 

As we step into our intelligent energy future, we’re working on more environmentally-sustainable power solutions for our customers.

Poles and wires: Through the distribution network to your fridge, lights and chargers

Once electricity has been generated, here’s what happens next:

  1. Substation transformers raise the voltage of the electricity so it can be transported efficiently over long distances through the transmission network.
  2. Energy flows through this transmission network from the generators to the distribution network.
  3. Substation transformers, at the other end of the transmission network, lower the voltage of electricity so it can be distributed through the distribution network.
  4. The distribution network, which consists of overhead powerlines or underground cables, carries electricity to its final destination; your home or business.

VPPs, microgrids and other interconnected power systems

The world of energy is changing. You might have heard that virtual power plant (VPP) technology is already being trialled here in WA.
 
While a “traditional” power plant, such as a gas or coal-fired power station, provides a central point where electricity is generated, there are other types of electricity systems with "decentralised" generation, such as VPPs and microgrids. 
 
Here’s how a VPP works:
  • A network of smaller-scale electricity generation and storage sources such as roof-top solar PV systems, batteries and electric vehicles is aggregated, or combined.
  • By combining these smaller electricity sources (often referred to as distributed energy resources or DER) into a VPP, they can then be orchestrated (or coordinated) in a manner to provide the same services to the electricity system as traditional centralised generation. This can help to keep supply and demand for electricity in the system in balance.

A microgrid is a local electricity system or grid which can be controlled separately from the SWIS. This means that it is not connected or it can disconnect from the SWIS and operate on its own to supply electricity to the homes or businesses within it.

WA's transforming electricity system

WA is going through an energy transformation like we’ve never seen before. As our population continues to embrace DER, more of our State’s power is being supplied by decentralised electricity generation sources (such as rooftop solar) than ever before.

The shift to more renewable and greener energy sources means positive things for the environment, but it puts an increased strain on the electricity grid, which wasn’t originally designed for the level of renewables (particularly rooftop solar) in the system today. Here’s what happens:

  • During the day, excess energy generated by solar panels is flowing into the grid when the sun is shining and demand is low. 
  • In the evenings, this solar generation disappears with the sun and the demand for electricity from other traditional generation sources goes up. 

If you graph this curve of supply and demand across a typical day, it looks a bit like a duck’s bill - which is why it’s known as the Duck Curve.

Our electricity grid is not designed for the two-way energy flow and large degree of fluctuation in supply and demand, so we need to find new ways to operate the network. 

We’re here to help you navigate these changes and work out what our intelligent energy future looks like for your home or business. This involves working with the WA Government and a range of energy industry participants to support WA’s DER Roadmap.

As the State’s largest electricity generator and a retailer of gas and electricity, Synergy serves over one million residential, business and industry customers. Find out more about who we are and what we do. 

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