Roland Bennet is a veteran on the annual network maintenance patrols that occur ahead of bushfire season. He’s been flying the lines for thirty years. This year, Roland is training newcomers to spot maintenance that’s needed on or around TransGrid’s electricity lines.
The patrols are vital to the safety of communities nearby lines, and for the safe and continual supply of electricity across the State.
The team working from the cockpit is extremely focussed.
“We’re in the air for eight to ten hours a day, fly over a transmission tower every two minutes, and travel at up to 40 knots an hour. It’s busy,” says Roland.
View from the top (L to R): Patrolling the lines; recording potential risks; boarding the chopper; vegetation near a transmission line.
On a transmission network that spans 13,000 kilometres, it’s vital to record all potential hazards quickly and accurately.
“Normally, there’s a pilot and two people to check the transmission line and surrounding area. One checks for vegetation that’s growing too close to the line, and the other checks for maintenance that’s needed on the line.
“If we see something than needs urgent repair, we report it immediately. For the most part, we record location, proximity to the transmission line, and exactly what the issue is.
This information is passed to teams who carry out the maintenance work. The patrols and resulting maintenance work are vital to minimising risk on the lines and surrounding areas ahead of summer. Hot summer days are typically when bushfire risk is highest, and also when the network is under pressure to supply the most electricity.
People may rarely see helicopters patrolling the lines, but come the cooler months Roland and the team reliably take to the skies.
“There are a few hard yards involved, but it’s a good feeling to know we’ve played a part in keeping the network in good shape. At the end of the day, it all comes back to keeping people safe.”
We can all help to keep our transmission network safe. If you see a potential hazard on the TransGrid network, call 1800 027 253 to explain the location and nature of the risk.
Future proofing the grid was in focus at the
Australian Clean Energy Summit in Sydney this week where TransGrid CEO Paul Italiano outlined the most promising renewable energy zones across the NSW, SA and Victorian tri-state area.
He joined Australian Energy Market Commission chairman John Pierce, Finkel Review panel member Chloe Munro and Clare Savage from Business Council Australia for the 'Future proofing clean energy - regulation for a smart, affordable and secure energy system' session.
The panel looked at how the Finkel recommendations will be delivered and what this could mean for consumers, business and the energy industry. Paul also outlined some of the challenges in harnessing Australia's abundant resources to establish the renewable energy zones flagged by Dr Finkel, comparing it to Texas which has successfully created policy-driven competitive renewable energy zones.
The panel agreed on the importance of moving forward with the Finkel recommendations endorsed by COAG as a package to provide the policy certainty that Australia needs to provide more affordable, secure and reliable energy and meet our Paris climate commitments.
Generator reliability obligations and the regulatory investment test for transmission were some of the key issues raised from the floor.
As we move towards an energy system which will feature an increasing proportion of renewable generation, the industry will need to take a different approach to security of supply. TransGrid's Tony Meehan, Executive Manager, Regulation explored this notion in his presentation which was part of a session titled 'The path to becoming a renewable superpower: transitioning the generation fleet to clean energy'.
Building on the theme of renewable energy zones introduced by Paul Italiano, Tony began his presentation by recognising Australia's newest wind farm.
White Rock Wind Farm, approximately 20km west of Glen Innes has been in operation for two weeks and is connected to the grid via TransGrid's White Rock substation. White Rock is one of a hundred substations across NSW and the ACT which help to move electricity from the source of generation to where it is needed.
The transmission network in Australia was built around coalfields and hydro. Tony noted that as an industry, we're looking at rebuilding the electricity system to enable the transition to a clean energy future. The introduction of more renewable energy means disruption at the source of generation. This is not the first time the system has been disrupted; technology has enabled the changes in the past and it will enable the changes needed for the future. A trajectory towards 100% renewable generation is feasible and the technical challenges associated with this transformation can be met in a way that is affordable for consumers.
Renewable energy zones will support the national electricity system by enabling connection of large-scale renewable generation in areas with abundant renewable resources. The need for different types of generation and the need to access it from different locations than we have in the past was a consistent theme across all presentations in the session.
Following the presentations, Dean Travers from ENGIE Renewables facilitated a panel discussion which covered issues such as the financial, regulatory and knowledge sharing challenges facing renewable generators that want to connect to the grid.
From left to right: Bin Lu (Australian National University), Donald McPhail (Energy Queensland), Tony Meehan (TransGrid), Catherine Way (DP Energy), and session chair Dean Travers (ENGIE Renewables).
For more information on the Australian Clean Energy Summit 2017 and to keep an eye out for dates for next year’s event, visit
Don Geddey has over 40 years’ engineering experience in power system analysis and planning. Don discusses the importance of stable system frequency and why it’s becoming more challenging to maintain.
A healthy frequency range of 49.9 – 50.1 Hertz
Power systems aim to provide customers with voltages of a near-constant magnitude and frequency. Frequency can be thought of as the ‘pulse’ of the power system. When the pulse rate is within a healthy range, the power system runs smoothly. However, a pulse rate that is above that range may indicate a rise in blood pressure, and below could be a sign of blood pressure dropping. Neither of these scenarios is where you want to be. The same goes for the power system.
Named after Heinrich Rudolf Hertz
, the Hertz measurement (Hz) refers to the number of cycles per second. The 50 Hz power supply we receive at our homes in Australia alternates between positive and negative values, providing 50 cycles every second. In other parts of the world (e.g. North America) the nominal system frequency is 60 Hz. In an Alternating Current (AC) power system in its normal or healthy state, all the connected generators rotate in synchronism, and the speed of rotation of generators determines the frequency of electricity generated. In Australia, electricity is generated at a frequency that is very close to 50 Hz.
For one 100-second period, Figure 1 shows the measured normally-occurring variations of frequency at four well-separated locations in the National Electricity Market.
Figure 1. Measured variations of frequency at four well-separated locations in the synchronised part of the National Electricity Market.
The plots of frequency variations in Figure 1 show that:
- There are always small, random frequency variations around the target value of 50 Hz.
- The frequencies at the different locations in the interconnected system are almost the same.
The target frequency of the power system is set to around 50 Hz because that is the frequency that many of the large industrial energy users connected to the network require for their machines to operate. Gas turbines for example, do not perform very well when they are not connected to a power supply of 50 Hz or very close to 50 Hz. Therefore, the power system frequency can be considered the ‘pulse’ of the power system, and is one indicator of power system health.
Balancing generation and demand: power in versus power out
A healthy power system operating with a near-constant system frequency requires total generator electrical power output (to supply the loads and losses) to be equal to the mechanical power input to them. The difference in these two powers is provided by changes in the kinetic energy of all the synchronous generators in the system.
The kinetic energy of a generator represents the energy stored in the rotating mass of the generator (including any connected turbine), and is proportional to a property known as inertia. Therefore, release of kinetic energy as electrical power generated, is known as inertia response.
When the input and output powers are mismatched, a corresponding change of the speeds in all the generators in the connected system occurs, leading to a change in the system frequency. As our power consumption is always changing, so the total power demand through the system is constantly changing. This creates power mismatches and frequency variations like those shown in Figure 1.
If a large generator is disconnected from the system, a significant power mismatch is produced, and the system frequency reduces at a fixed rate. If there is no change to the mechanical input powers of the generators that remain connected, the frequency will continue to fall at that fixed rate until a system collapse occurs. More input power (or less power demand) is required to arrest the reducing frequency and stabilise the system.
Figure 2 shows the frequency in Adelaide on 14 March 2005, when different events produced power mismatches and substantial frequency variations. A system event caused sudden reductions of the mechanical powers to two large generators in South Australia. This produced a drop in system frequency and an increase in the power flow from Victoria. About two seconds after the initial disturbance, because of the increase in power transfer from Victoria to South Australia beyond the capacity of the VIC-SA interconnector, it was automatically opened, leaving South Australia electrically isolated from the rest of the National Electricity Market.
Figure 2: The measured variation of frequency in Adelaide following a sequence of events that left South Australia electrically isolated.
After the trip of the VIC-SA interconnector, the Adelaide frequency fell at a rate of about 1.3 Hz per second.
In this 2005 case, the fall in Adelaide frequency was subsequently arrested by actions that restored the power balance in South Australia.. Generators increased output power and some loads were disconnected.
In September last year, a very similar sequence of initial events (loss of SA generation plus tripping of the VIC-SA interconnector) occurred, but the consequence was quite different and the isolated South Australian system was blacked out. The main reason for the different outcome was that the kinetic energy released from the connected generators was much lower, due to the smaller number of synchronous machines connected to the South Australian system at the time, producing a much higher rate of frequency reduction and responses that were too slow to be effective.
The mechanisms for power balancing are commonly addressed by many inter-related terms such as; spinning reserve, Frequency Control Ancillary Services (FCAS), and system inertia response. Some aim to slow the rate of frequency reduction, while others aim to increase the ‘power in’ to stop the frequency drop and to bring it back to near 50 Hz. The mechanisms differ from each other, mainly in respect to the speed at which they can react, as shown in the following plots.
Frequency Controlled Ancillary Services agreements
Activating FCAS is the next step. The Australian Energy Market Operator (AEMO) has a number of FCAS agreements
in place, ready to go should the need arise. When the frequency is reducing, if the provider that has entered into an FCAS agreement increases their output they receive a financial incentive in recognition of providing an increased amount of power to support the system. The machines are programmed to increase the amount of (mechanical) ‘power in’ as the frequency goes down. The generators measure the frequency and know when they need to increase their power. They are always ‘checking the pulse’ of the system.
There is no human intervention during the event; it is all controlled using technology and everything is programmed. As soon as a generator enters into an agreement they activate a control kit. The FCAS contracts are managed by AEMO.
Some machines can provide power in about six seconds, some machines can do it in about 60 seconds, and some machines can do it in five minutes. So, the faster they can provide it the better, but it depends on the technology within the machines.
Fast Frequency Response to manage the energy system of the future
When we don’t have enough of those rotating machines across the system, for example when coal or gas fired power stations close, the amount of inertia available in the system reduces and it becomes difficult to keep the frequency constant, particularly just after a disturbance. With the retirement of several large generators scheduled to occur within the next 5 years, the number of machines that can increase their powers within the required 6 second window is also reducing.
One challenge is to find a way of providing something equivalent to stored kinetic energy into the system within a short period of time, specifically, referred to as Fast Frequency Response (FFR). As we transition to the energy system of the future, a number of possible solutions are being investigated, including the installation of synchronous condensers, and large-scale battery storage. Another possibility is for wind farms to make use of the kinetic energy stored in their rotating turbine blades, when the frequency falls. This process of providing ‘synthetic inertia’ requires the wind farm to reserve some of its output power capability, so that it is available when needed.
The first turbines at White Rock Wind Farm, 20km west of Glen Innes in the New England Tablelands, began generating energy on Friday 7 July.
The renewable energy project involved design, construction and commissioning by TransGrid and our subcontractor Zinfra of a 132/33 kV substation and dual circuit 8km transmission line to connect the new wind farm to the grid. Stage 1 of the project commenced in May 2016 and consists of 70 turbines. Once fully operational, the 175 MW White Rock Wind Farm will generate enough renewable energy to power approximately 75,000 homes annually.
If you see a low-flying helicopter moving along the electricity transmission lines, you've likely spotted a chopper on an aerial maintenance check. Each year, helicopters patrol almost 13 000 km of transmission lines and infrastrucure that make up TransGrid's network. Teams aboard the choppers look for infrastructure that needs to be repaired, or trees and shrubs in easements that could pose danger in a fire or storm.
2017 aerial patrol dates
In 2017, aerial maintentnece patrols are occuring between July 31 and August 29 in the following areas and their surrounds.
31 July - 3 August
|Northern: Gloucester, Newcastle , Port Macquarie, Taree , Cessnock, Liddell, Murrurundi, Scone, Hawkesbury River, Wisemans Ferry. |
Central and Sydney: Lithgow, Megalong Valley, Campbelltown, Windsor, Penrith, St Albans, Wisemans Ferry.
8 August - 12 August
|Central and Sydney: Wollongong, Heathcote, Appin, Mittagong, Camden, Penrith, Marulan, Albion Park, Robertson, Kangaroo Valley, Nowra, Dural, Sydney East, Holsworthy, Georges River.|
14 August - 18 August
|Southern: Coleambally, Darlington Point, Deniliquin, Griffith, Wagga Wagga, Yanco, Finley, Uranquinty, Blowering Dam, Dederang, Gadara, Jindera, Talbingo, Tumut, Bannaby, Marulan, Porters Retreat, Yass, Canberra. |
21 August - 25 August
|Southern: Bannaby, Burrinjuck, Canberra, Capital Wind Farm, Cooma, Cowra, Geehi, Gullen Range, Guthega, Jindabyne Pump , Murray, Murrumburrah, Queanbeyan, Shoal Haven River, Snowy Adit , Spring Flat, Swallowtail Pass, Tumut, Wagga Wagga, Williamsdale, Yass.|
Northern: Armidale, Coffs Harbour, Glen Innes, Grafton, Gunnedah, Inverell, Kempsey, Koolkhan, Lismore, Moree, Narrabri, Nymboida, Port Macquarie , Tamworth, Tenterfield
28 August - 29 August
|Northern: Armidale , Murrurundi, Tamworth , Dumaresq, Texas.|
Aerial patrols form part of a comprehensive, year-round asset inspection and maintenance program.
(Planned patrol locations may change due to weather conditions or scheduling considerations.)
Patrols reduce risk in the event of a bushfire or storm
Maintentnece patrols are vital for the safety of communities nearby easements, and for the safe and continual supply of electricity across the State.
You likely know that scrub can burn quickly and with devastating impact on a hot, dry day. You may be surprised to learn that a 10 metre tall tree can have a flame height of more than 30 metres in a bushfire. It’s vital that clearance zones are observed in transmission easements.
Have questions about patrols in your area?
Call TransGrid toll-free on 1800 222 537.
It's been a busy couple of months on the conference circuit for TransGrid with speaking engagements at the EUAA National Conference, 4th Australasian Emissions Summit 2017, and Australian Energy Week 2017. Dr Alan Finkel released his report and we published our Transmission Annual Planning Report 2017.
TransGrid recently held community information sessions for the Powering Sydney's Future project. The project team met with local residents at five sites along the proposed route, including Campsie Shopping Centre, Marrickville Metro, Bankstown Shopping Centre, Summer Hill Community Centre and Sydney Park. The team provided information about the project and invited feedback on the proposal.
Aadil and Kek from TransGrid's Powering Sydney's Future project team during one of the recent community engagement sessions
Community engagement is an important part of the project planning process. As part of the Regulatory Investment Test for Transmission (RIT-T) consultation process, we have been investigating a series of credible options to find the most reliable, affordable and sustainable solution to secure the future electricity supply for the Inner Sydney area. Community input is an integral part of this process.
You can find out more about the community engagement for Powering Sydney's Future, including the key themes identified and feedback received, by viewing our Community
Consultation Report. Information regarding the route selection process
undertaken by TransGrid can be found on our Powering Sydney's Future webpage.
Preliminary Environmental Assessment (PEA) has been submitted to the NSW
Department of Planning & Environment, and can be viewed on the Department's website.
Alongside the investigation of a network solution, we have also been investigating non-network solutions to meet Sydney's electricity needs. Following from the Expressions of Interest (EOI) received in October 2016, eleven responses were received and investigated to determine their viability as a solution. Following thorough analysis, we have determined that a non-network solution can be utilised and would enable the project to be deferred by one year.
More information on the analysis of these options is available in the Project Assessment Draft Report (PADR). Submissions for the PADR closed on 23 June, 2017 and will be used to inform the Project Assessment Conclusions Report (PACR). Based on the current program, it is estimated that the PACR will be released in late 2017.
If you would like to be kept updated on the planning progress, or have specific questions regarding to the project, you can contact TransGrid through email@example.com or call the Powering Sydney's Future project team on 1800 222 537.
Electricity generation from rooftop installed and grid connected PV solar panels has been steadily increasing over the last 5 – 7 years. The following figure shows the increasing interest in connecting large solar plants to the NSW grid over the last four years.
Source: AEMO Generation Information
The capacities of the solar farms presently connected to the NSW transmission grid are in the range of approximately 50 MW – 100 MW. Significantly larger farms, which would have a capacity of over 500 MW, are under consideration for future grid connection.
While it is a fundamental truth that the sun will be rising from the east and setting in the west every day, the solar energy we receive onto a solar PV panel is significantly variable and depends on the prevailing weather conditions. The most pertinent weather condition is cloud cover.
Because of the cloud cover and the movement of the clouds, the solar PV generation, irrespective whether it is from rooftop panels at our houses or from the large grid-connected solar plants, can vary widely over a short period. The following figures show, the variation of the solar power generation from a grid-connected solar plant over a day.
It is clear that we need to expect volatile periods of power generation as well as steady periods of power generation from the solar plants, depending on the cloud cover and movement of the clouds.
Due to the wide geographical spread of the rooftop PV installations across the country, the variations of power generation due to cloud cover and their movements will cancel each other out, and the total generation would be fairly steady. The same can be expected from total power generated from the grid-connected solar plants, when a significant number of solar plants are developed and widely geographically dispersed.
Held in Melbourne from 20-23 June 2017, Australian Energy Week 2017 brought together more than 400 delegates for a wide range of sessions, panels, networking opportunities and a comprehensive learning experience. TransGrid was pleased to be represented among the line-up of speakers, which included Chief Scientist, Dr Alan Finkel presenting on his blueprint for the Future Security of the NEM.
Dr Alan Finkel talking through the evolution of electricity generation
Dr Finkel commented that there had been a lot of interest in the processes of the review. Working to a brief to look at security, reliability and affordability of electricity into the future, the vision that the panel took into the review was for a truly world-class electricity system, supporting our prosperity and our economy of the future. "Don't interpret that as a negative statement about where we've been in the past, but it is a statement about what we need to preserve for the future," Dr Finkel said.
Dr Finkel thanked those involved in the extensive consultation which was undertaken throughout the review. He noted that of more than 390 submissions received, there was overwhelming support for the notion that business as usual is just not acceptable. As part of the review, the panel visited regulators and operators across Europe and the United States, and commissioned a review of international best practices from the International Energy Agency. The panel found this part of the consultation to be a particular 'eye-opener': the one thing that Australia didn't have that some of the other countries did have was a long-term strategic approach to dealing with the transition to a low carbon future.
With a background in science, business and electrical engineering, Dr Finkel acknowledged the value of taking an engineering approach into the review; in particular, taking a problem, analysing it and coming up with solutions. He noted that the blueprint put forward by the panel was not a perfect solution, nor a solution of compromise. The panel had delivered an optimised solution.
Investigating solutions to ensure security of supply for a new energy system
The need for a plan to enable the transition from what Dr Finkel described as NEM 1.0 to NEM 2.0 was a key theme throughout the conference. TransGrid took part in two of the conference streams held on Day 2 and both presentations highlighted different aspects of the plan that we recently put forward in our Transmission Annual Planning Report 2017; system security, demand management and energy storage.
Gerard Reiter, Executive Manager, Network Planning & Operations presented in the Future Grid stream leading into a session on using increased interconnection to strengthen security of supply. In his presentation on ‘Investigating solutions to ensure security of supply for a new energy system’, Gerard discussed AEMO’s projection that coal-fired generation in the NEM will reduce from 74% in 2016-17 to 24% in 2035-36, and the need for Australia to connect up to 22 GW of new large-scale wind and solar generation before 2036.
Gerard Reiter presenting in the Future Grid stream at Australian Energy Week
Gerard also highlighted the benefits of an increased level of interconnection across the NEM, the need for further investment to enable connection of large-scale renewable generation in areas with abundant renewable resources, and the regulatory reforms required to support the transition.
Following his presentation Gerard joined John Bradley, Chief Executive Officer, Energy Networks Australia, and Joe Dong, Head Clean Intelligent Energy Networks, University of Sydney, for a panel discussion facilitated by Hugh Gleeson, Non-Executive Director, Energy Queensland, on 'Increased interconnection- saviour of the NEM of the next stranded asset?'
The panel expressed support for many of the recommendations put forward by Dr Finkel and his taskforce and agreed that a strategic overall approach is needed to ensure the energy needs of the future are met securely, economically, and for the benefit of the community.
A network's perspective on the potential of energy storage
Andrew Kingsmill, Manager Network Planning presented in the Digital Disruption & Innovation stream as part of a session examining the potential of storage as a true disruptor. In his presentation 'a network's perspective on the potential of energy storage', Andrew put forward a vision for the energy system of the future which is outlined in more detail in the first chapter of our Transmission Annual Planning Report 2017. In particular, Andrew explored what the system might look with an increased amount of energy storage and what the transition might look like as we go from centralised generation to distributed generation in the NEM.
TransGrid's plan for the energy system of the future is outlines in our Transmission Annual Planning Report 2017
Andrew also touched on TransGrid's research and development of technologies such as battery storage, deployment of OpenADR, and the technologies proposed and being further explored to meet an expected constraint on the part of the transmission network which supplies the Inner Sydney area. This is the non-network component of the Powering Sydney's Future project- full details including our recent stakeholder engagement report are available via our consultations page.
Want to be part of it
next year? Australian Energy Week 2018 is scheduled for 8-11 May 2018. Keep an
eye on the Energy Week website for details.
Planning excavation work?
Stay safe when you're excavating. It's vital to know whether there are high voltage electricity cables in the intended area of work. Follow the mandatory enquiry process below to help keep you and your community safe.
- Submit an enquiry to Dial Before You Dig (DBYD), to determine if there are any underground electricity assets in the vicinity.
- If there are high-voltage electricity cables in the intended area of work, you will receive a TransGrid DBYD response.
- Contact TransGrid to discuss the DBYD response. TransGrid will determine whether the proposed work can proceed, based on whether it poses a risk to its asset or public safety. Damage to high voltage electricity cables could lead to serious injury or death, and widespread electricity supply interruptions.
If TransGrid determines that it's feasible to excavate in the intended area of work, it's time to consider on-site safety.
Precautions and responsibilities exist to keep you safe.
Minimum precautions to take before you start work:
- Notify TransGrid at least two business days before you plan to start work. You will need to discuss necessary safety aspects, work methods and whether a TransGrid representative will need to be present to supervise the site during work.
- Ensure that a TransGrid site representative is present before you commence work, if required.
- Whilst work is performed, keep plans supplied by TransGrid on-site at all times.
- Do not modify the extent of work in the vicinity of the cable without prior notification to TransGrid.
Complete a Hazard Assessment before you start work, to ensure that:
- All hazards have been identified and assessed
- All members of the work crew have been made aware of the hazards
- Appropriate controls are in place to avoid the hazards identified
- Appropriate controls are in place to ensure the safety of the public
- Traffic management plans have been approved by the road owner.
- Commence excavation work only when you are certain that you are compliant with instructions issued by TransGrid.
- Before you commence machine work, identify the correct location and depth of the cable trench and any associated plant (such as pits and joint bays). This can be done with assistance from a TransGrid representative.
- Carry sufficient public liability insurance to cover any claim resulting from property damage or personal injury. (TransGrid accepts no responsibility or liability for any damage to property, machinery or personnel injury, as a result of any incident caused by other parties working on or in the vicinity of TransGrid assets.)
- Secure necessary traffic control, if your work is near a road. TransGrid accepts no responsibility for the control of traffic.
- When backfilling an excavated area, make sure you're working to TransGrid's and the Roads and Maritime Services' requirements. Always check the specific reinstatement of excavations requirements for your work. Typically, stabilised backfill consisting of 20:1 sand cement should be installed and compacted in 300mm layers below the road pavement, or as requested by the TransGrid representative.
- If there's damage to TransGrid infrastructure, immediately notify TransGrid by calling the emergency response line on 1800 027 253.
Further advice and resources