Ergon’s innovation engineer Stephen Richardson explains the company’s Grid Utility Support System (GUSS), a network-side energy storage product developed for customers in remote areas served via the Single Wire Earth Return (SWER) network.
GUSS is an intrinsic part of the SWER, but it isn’t going to be a solution for every SWER customer at this point. However, it’s worth taking a brief look at the SWER distribution technology, which is a vital energy lifeline for many parts of rural and remote Queensland.
We manage more than 164,000km of SWER – making it one of the largest distribution systems in the world. SWER was mostly rolled out in record time and for a record low cost in the late ’70s and ’80s. It can still be considered a great economic solution to electrify large areas of country like rural Queensland.
Back in the day, a customer’s energy requirements were likely to be a fridge, lighting and radio. Today, however, the rural home and farm has more electrical items such as fridges, cold rooms, computers, lights, radio, hot-water systems and air-conditioning units. It’s inevitable therefore our customers’ expectations, and the demand for reliable supply via SWER, have increased since the ’80s.
Prudently maintaining a reliable and safe supply to relatively few customers has called for innovative thinking over the years. GUSS is the latest example, albeit a futuristic one because it involves a battery energy storage system. We have 20 GUSS units slated for deployment on the SWER network and we have chosen the most needy areas for initial deployment.
It’s important to keep in mind that this 21st century GUSS technology is being connected to the same 20th century SWER system, which was designed for a simple lifestyle.
Some may say pull down all the SWER and install a three-phase network, while others say the limitations of SWER comes with the decision to live in remote areas. The reality is there is no set answer or solution. But we know the cost to completely replace SWER with a three-phase network is prohibitive and unrealistic, especially as the exciting work in renewables and micro-grids gains more traction.
Our SWER network requires innovative solutions to meet new needs and expectations, as well as extend its shelf life.
The evolution of GUSS
Each GUSS unit is an advanced, cost-effective technology solution that can reduce peak loads and support reliable voltage levels for up to 100 customers.
But our latest GUSS did not happen overnight and, looking at the timeline, I can say they have been a long time coming.
GUSS evolved from the work by Ergon in the 1990s that went into the proven stand-alone power systems known as Remote Area Power Supplies (RAPS) in the 1990s.
RAPS were developed to supply isolated homesteads by incorporating energy storage (lead acid batteries) coupled with solar and/or diesel generation. The RAPS driver here being similar: the prohibitive costs of network augmentation for an isolated and relatively small number of customers.
When we first started looking at the GUSS concept, there was no suitable off-the-shelf product available, so we did our own research and development. An R&D project was set up to develop and trial the GUSS concept and drew on our knowledge and experience with RAPS.
There followed a long period of industry review and product development which culminated in 2011 with Ergon partnering with West Australian firm Magellan Power Electronics to build two trial 25kVA 100kWh concept systems. These were initially installed on the Atherton Tablelands before being moved to Laura SWER near Cooktown for longer term testing.
That early GUSS trial enabled us to take the next exciting steps. In 2014 the company awarded a contract for the purchase of 20 GUSS units to the US-based firm S&C Electric.
Each GUSS unit weighs around 3.7 tonnes and contains 56 lithium-ion batteries with a 100kWh rating and 800 volt maximum operating voltage. The units are mounted on a single 5.3m x 1.6m skid which means they can also be transported to another site if ever required.
A communications system enabling remote monitoring of each GUSS system was developed by us. Due to the remote locations of GUSS this is a vital link.
Our GUSS units will be deployed to rural and remote parts of our SWER network. This means you’re most likely to find a GUSS 100km from the nearest rural town, up to 200km from the start of a SWER line, and up to 400km from a major centre. Given the rural and remote location that the GUSS units will be installed, all communications to the units will be via satellite services.
While GUSS is a new and innovative device, we want the unit to fit into our network like any other piece of hardware. To enable this, every effort has been made to reuse current equipment standards and tooling to keep the installation costs down. Installation is relatively straightforward and requires minimal interruption to supply.
Maintenance of the GUSS units is not expected to require a network outage either. Approaching the installation in this manner has meant we have only had to create one new procedure to install GUSS and that is to physically place the unit on the ground.
The GUSS is placed on precast four-piece concrete slab (which is bolted together on site) and then a simple three-string fence is erected around the unit to keep livestock out. Connection to the SWER line is no different to customer’s house via a 25kVA Transformer and uses the same fitting and fixtures.
Using the approach of using standard designs, equipment, tools, and procedures has ensured the cost to install a GUSS is as economical as possible.
GUSS’s biggest benefit is to our customers’ experience. As a network-side storage system, GUSS services a whole SWER line, rather than an individual customer. The GUSS is programmed to ensure that its operation is always ensuring a positive benefit for the customer experience.
A single GUSS unit is able to reduce the load on a SWER by 25kVA and improve the voltage seen at the end of the SWER by up to two per cent. This reliability comes at a lower cost than traditional augmentation – around 35 per cent – and all customers ‘upstream’ and ‘downstream’ of a unit can expect to see an improvement in voltage levels.
While GUSS is optimised for a SWER line, the concepts and design principles of GUSS are able to be used for both home energy storage and also three phase energy storage systems.
How we have designed GUSS is one feature which I believe makes GUSS a game changer in the industry. If the SWER to which it is connected no longer needs the support of a GUSS – say due to a reduction in load or network reconfiguration, the skid-mounted GUSS can be relocated to another site.
Stephen Richardson presented ‘Scale Energy Storage Lessons And Learnings’ at the Energy Networks 2016 Conference and Exhibition on Friday, May 20.