TransGrid – Digital Substation

1. Executive Summary

TransGrid has achieved benefit for its stakeholders including consumers, shareholders and regulators by implementing Digital Substations based on the international standard for communication protocols, IEC 61850. TransGrid manages a high voltage power transmission network consisting of 109 existing substations and over 13000 km of transmission lines. The bulk of the substations were constructed in the 1970’s and 1980’s generally utilising technology that was appropriate at that time but the technology is reaching the end of its reliable life and requiring replacement to maintain a safe and reliable transmission network. Digital Substations will be implemented on future new and replacement capital projects.

2. Description of Project

2.1 TransGrid’s Journey in Digital Substations

The Digital Substation project has created significant benefits to all its stakeholders. It has enabled the delivery of lower cost refurbishment projects with greater safety and reliability.

TransGrid manages a high voltage electricity network with over 13000 km of transmission lines and 109 substations. The substations commenced commissioning in the 1950’s and due to reliability and obsolescence risks are becoming due to for replacement. Additional to this the transition to renewal energy sources has accelerated the need to develop new substations to connect these generators. Based on the corporate plan TransGrid’s asset management strategies includes strategic themes to:

  • Provide safe and reliable electricity
  • Develop an efficient network
  • Seek new innovations and technologies.

In order to deliver to these themes, TransGrid developed a Digital Substation strategy to implement a new technology. The strategy involved not only technological change but also culture and operational practice changes. The strategy was endorsed by senior management and the project started with market research then moved to a study of options, evaluation of options, selection of vendors, and proof of concepts, before moving on to the first implementation of the new technology at Avon Substation. Figure 1 provides an overview of the digital substations strategy. With the successful implementation of the base architecture at Avon, TransGrid is now moving towards implementation of sensors (Low Power Instrument Transformers or LPTI) and virtualisation.

Figure 1 – TransGrid’s Journey in Digital Substations

TransGrid have been able to implement numerous new technologies into the substation that not only improves safety and reduces cost but also allows quicker delivery of Substation projects. The Avon Substation secondary systems project involved replacing all of the cabling and secondary equipment including the Protection, Control, Metering and Condition Monitoring systems with Process Bus systems that dramatically reduces drawings, panels, wiring, cabling and overall reduces the project costs by up to 30%.

TransGrid carried out an extensive assessment of substation secondary system design based on the implementation of IEC61850 at the substation and process bus level which brought out the business case for full digitisation. This was not just a case of should we do it, with 30% project cost savings the implementation is a must in order to maximise benefits to TransGrid and its stakeholders. Figure 2 shows where this architecture fits in a substation system.

Figure 2 – Scope of Digital Substation Architecture

The first substation to realise this new technology was Avon 330kV switching station. In this Digital Substation, new standards were implemented including IEC61850-9-2LE, IEC61850-8-1 IEC62439-3 (PRP) and time synchronization based on IEEE1588 standards.

It must be emphasised that the evolution and adoption of IEC61850 is intended to encapsulate all aspects of secondary design and should be viewed holistically as a system and not as individual standalone components. This allowed a complete re-think on what a substation secondary system is and how to implement it. As a result of this approach we were able to implement many improvements over existing secondary systems while reducing overall costs.

2.2 Benefits of Solution

Reduction in copper cabling/trenching:

This is a major benefit for secondary systems for green field substations and also for refurbishments where secondary cabling needs to be altered due to aging or design changes.

Reduction in building size:

Process bus Intelligent Electronic Devices (IED) are typically half the size compared to traditional IEDs and no wiring or links are required. This along with a unique panel design allows more IEDs accommodated in a panel and therefore drastically reduced (80%) panel space required within a substation.

Faster commissioning of substations:

Due to the smaller size of panels and limited cabling involved between panels, almost the entire secondary system for a substation can be built and thoroughly tested in a laboratory. Not only does this allow greater control over quality of testing but it can be done at a fraction of the cost of testing done at remote sites. It is much easier to engage vendors or specialists to address specific issues when the tests are done in a lab rather than a remote site. Once the system leaves the laboratory with thorough functional and interface checks done, the site work is reduced to perform minimal commissioning checks. This drastically reduces labour costs and time associated with commissioning – about 50% savings. This is a significant advantage in countries where labour cost is very high.

Standardisation – Reduction in System drawings:

Standardisation was heavily used at the bay level to make merging unit configuration similar and to allow changes to the copper interface without changing the underlying digital messages. Hence the bay information is always the same even though the primary equipment may vary. In this way the interface between data digitisation and data usage is standardised. This also significantly reduced the number of drawings – approx. 90% – required to implement the design. This approach opens up the possibility of standard indoor and outdoor cubicles that can be ordered irrespective of the project, therefore simplifying sourcing requirements.

Simplified maintenance:

With better defined test and simulation modes in IEC61850, maintenance and commissioning tests can be done more efficiently. Also, visualisation, test and diagnostic tools are evolving that can greatly help the maintenance regime. Remote diagnostics are possible which will reduce visits to site. The cumulative savings in this first Digital Substation project is around 30%, so far exceeding the initial expectation in the business case. These savings are expected to be improved on as the maturity of designs progresses with further implementations.

Energy network customers will directly benefit from all of the above innovations through an overall reduction in the capital cost required to implement and maintain future secondary systems, improved safety standards, timely delivery of projects and enabling increased connection of renewable generation to the Grid.

TransGrid’s first Digital Substation is now in full operation at Avon substation. TransGrid have followed a process that has delivered complete renewal to all secondary systems within the substation. Starting with research, then completing a proof of concept and finally implementing Avon Digital Substation.

A very important aspect of the entire process is that this was a business-driven innovation and it rested on a sound business case with both short and long term financial benefits. There were valuable lessons learned during the process that will guide future designs.

3. Program and Project Management

3.1  Project Management

The delivery of the Digital Substations project was a major project, subject to the organisational governance and project management processes, including a Project Manager, monthly reporting to the project sponsor and executive, change management and relationship management with the vendor.

The steps in managing the delivery of the Digital Substation were performed consistent with TransGrid’s capital investment governance process, including:

  1. Needs identification by the Head of Asset management for replacement of secondary systems in order to assure the reliability of the network. The opportunity to innovate and obtain value based on the new IEC standard was identified during the asset renewal process.
  2. Initial evaluation and scoping was undertaken and an initial funding approval that allowed detail design and costing to commence was submitted and approved by the CEO. This is referred to as DG1 (Decision Gate 1) within TransGrid’s capital governance process.
  3. Detailed options costing and feasibility was then undertaken that showed significant benefit from implementing a ‘Digital Substation’ solution. A full business case was then developed and presented to the CEO for construction approval at the first site (Avon Substation). This is referred to as DG2 (Decision Gate 2) within TransGrid’s capital governance process.
  4. The first implementation of Digital Substation architecture was completed at with the Avon Substation project in 2019.

3.2 Stakeholder Engagement

As the project involved a wide variety of stakeholders, a stakeholder management plan was developed which highlighted the need for:

  • A steering committee – to drive decisions within the project
  • A technical committee – discuss detailed technical aspects of the change
  • Road shows – to distribute the upcoming changes to the wider audience
  • Newsletters – notification of milestones to the whole business

Figure 3 shows the matrix approach that was used to determine the requirements for effective risk based stakeholder engagement. As a result of this the following responsibilities were identified.

  1. Technology and Innovation were responsible for the ultimate design and project management for the project, including liaison with internal and external stakeholders.
    1. Substation and Communications Design Groups were to assist in providing technical expertise, developing solutions, developing and rolling out standards.
    1. Network Services and Operations Technical Services group were to assist in developing and rolling out standards, test procedures, developing maintenance standards and training.
    1. Network Services and Operations Regional Managers were to assist in rolling out standards, test procedures, developing maintenance standards and training.
    1. Project Development were responsible for the design, procurement, environmental approval, overall project and contract management and for expenditure control and schedule management.
    1. Plant Standard and Equipment Procurement were responsible for the provision of the procurement services.
    1. People Strategy and Corporate Services/ corporate affairs were responsible for media and government liaison. The External stakeholders include:
      1. Distribution Utilities – TransGrid had to investigate the viability of tele-protection schemes, with the local end (TG) utilising IEC-61850 and the remote end utilising non IEC-61850 solution
      1. Australian Energy Market Commission
      1. Australian Energy Market Regulator
      1. IEC-61850 IED Manufacturers.

The implementation of the new technology doesn’t come without new risks. The risks were managed through the process and documented on project risk registers and within the Safety in Design process. To ensure all risks were captured a comprehensive Stakeholder Management Plan was implemented that involved many workshops, a project Blog, a technical expert panel and a project steering committee. Stakeholders engaged included Senior Management, Asset Management, Design Teams, Network Operations, Commissioning Staff, Maintenance Personnel and the Network Operator.

Figure 3 – Stakeholder engagement assessment

3.3  What’s next for Digital Substations

TransGrid is currently working on designs for two more much larger Digital Substation projects which will utilise full process bus technology. These projects were identified as preferred options during the evaluation process as they were able to demonstrate a reduction in capital cost, lower environmental impact and better safety during commissioning.

Avon Digital Substation is just the beginning of the journey; the present strategy for secondary systems puts TransGrid on a new path with Digital Substations. With successful implementation of the base architecture work has now commenced to unlock the value it provides. This will involve the following phases of work:

  • Integration of low power instrument transformers. These are state-of-art fibre optical current sensor solutions that will deliver further significant operational performance, environmental, safety and substation engineering benefits supporting future smart grid substation investments.
  • Integration of switchgear that will lower the footprint of the substation as well as providing even faster commissioning and testing.
  • Secondary virtualisation with previously discrete hardware components will be virtualised in a software environment providing control and protection through the integrated digital interfaces.

4. Summary

Digital substations is delivering significant benefits in line with the TransGrid business strategic themes and associated asset management objectives throughout the lifecycle of the asset as shown in

Figure 4.

Figure 4 – Lifecycle value realisation

The completion of Avon substation is a further step in TransGrid’s asset management journey by delivering against its objectives. The following table shows the corporate and asset management objectives that are being met by being a successful project.

Corporate themeAsset Management Objective
Safe/reliable powerManage Network Reliability
Create an efficient high performing networkManage assets efficiently without compromising security holder ad consumer value. Ensure accessible, relevant asset management information is available to inform business wide decisions.
Invest in transmission to support the energy transitionImprove capability to support future energy system development
Seek new innovations and technologiesLeverage Asset Management to support new technologies and innovations that improve or grow our business
Grow our infrastructure services businessSupport growth though developing intellectual property in efficient network solutions
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