Generator Connections to the Western Victoria Transmission Network. Questions and Answers

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1 Generator Connections to the Western Victoria Transmission Network Questions and Answers March 2018

2 What is the issue? The map to the right shows a snapshot of the Western Victoria transmission network. There are two wind farms, Waubra Wind Farm (WF) and Ararat WF, connected to the Ballarat-Waubra-Horsham 220 kv transmission line (BATS-WBTS-HOTS). Other recently committed projects along this line with planned commissioning dates between late 2018 and early 2019 include: Crowlands WF (80 MW) Bulgana WF (204 MW) Murra Warra WF (226 MW) With these five wind farms connected, the BATS-WBTS-HOTS line will, at times, be loaded beyond its thermal capacity. Associated network constraints may result in limitations on the generating capacity of these wind farms. There has been significant interest in the development of new wind and solar farms in North-West Victoria. AEMO has received a number of enquiries and applications from developers interested in connecting to the 220 kv lines at Horsham-Red Cliffs (HOTS- RCTS), Moorabool to Terang (MLTS-TGTS) and the Red Cliffs-Wemen-Kerang (RCTS- WETS-KGTS). With a commissioning date of mid 2018 these include; Wemen SF (110MW) Bannerton Solar Park (100MW) Karadoc solar farm (90MW) Yatpool solar farm (81MW) Battery Energy storage system at Ballarat (30MW) There have also been several hundred megawatts of newly committed wind and solar in South-West New South Wales, which also may impact generation import into Victoria via RCTS. If further development proceeds as suggested, this will add to the thermal constraints in this area. The connection of new generation in NW VIC has contributed to Marginal Loss Factors (MLF) in the area decreasing, with some generators experiencing a decline in over 3% AEMO 2018 Questions and Answers 2

3 from 2017/18 to 2018/19. It is likely that with the addition of more generation in the area loss factors will continue to fall. What does this mean for me as an existing or future wind or solar farm developer? If the loading along the lines in this area exceeds the thermal limit, the amount of generation output that can flow through that line will be restricted. When that happens, generators or groups of generators located on these lines will dispatch at less than their full output. This problem will be exacerbated as the number of connections increase along these lines. Where considered reasonably necessary for adequate system operation and maintenance of power system security, generators below 30 MW will also be required to be included in central dispatch. The relatively low system strength in North-West Victoria may result in additional constraints and works may be required to ensure the stable operation of additional generation. These works may include installation of synchronous condensers or other plant to raise fault levels. For more information on system strength, see the Interim System Strength Impact Assessment Guidelines published by AEMO. This document outlines the principles and methodologies used when assessing the system strength impacts with a new or modified generating system connecting to the National Electricity Market (NEM). In some cases, the special protection schemes used to manage power system security may result in ancillary services and stability limit constraints. Please note that these current interim guidelines will be replaced with a final version from 1 July Does this mean my wind or solar farm s output will be affected? Several factors can affect the order in which generators are dispatched, and the amount by which they could be constrained. In addition to variable operational conditions and economic considerations (including bid amounts), the location of each wind and solar farm relative to the constraint and to each other may also be a significant factor. Emerging voltage stability and ancillary services constraints are likely to result in precontingent constraints applied to generators (or groups of generators) to limit the total lost generation for a single contingency to approximately 600 MW. Whether a particular generator is impacted will depend on its characteristics, location, system strength limitations and connection configuration. Detailed studies are required to assess the potential impact of each project, noting that any future connections could materially change the outcomes. AEMO 2018 Questions and Answers 3

4 Is there any way AEMO can prevent these system constraints? AEMO is assessing whether it can plan to augment the capacity of the relevant transmission lines. This can only be justified if there are sufficient net benefits to the broader market. AEMO must process every connection application it receives and make offers to applicants who meet the relevant National Electricity Rules requirements. Subject to certain conditions, AEMO can make current network data available for intending participants to conduct their own studies on the implications of these constraints on their proposed projects. How can AEMO address this situation? AEMO is currently conducting a Regulatory Investment Test for Transmission (RIT-T) to assess solutions to address the forecast network congestion in Western Victoria. The purpose of the RIT-T is to identify credible options to relieve congestion and to increase the capability of the power system to facilitate the connection of new generation in this area where it will result in a positive net market benefit. A number of reports are published throughout the RIT-T process that outline the identified options and seek consultation from stakeholders: The first report, the Project Specification Consultation Report (PSCR), was published on 21 April A link to this document can be found here. The second, the Project Assessment Draft Report (PADR), will identify the market benefits for all credible options, and recommend the option that returns the highest net market benefit as the preferred option as well as optimum timing for implementation. This report is scheduled to be published mid The third, the Project Assessment Conclusions Report (PACR), will respond to submissions in response to the PADR and conclude on the preferred option. This report is scheduled for publication in early Assuming a preferred solution is identified, the project approvals, design, and construction timeframe is likely to be 4-7 years. Is there anything I can do to reduce the impact of these system constraints? There are a number of things that could assist in alleviating the network congestion, including; If your project is in its early stages, if possible consider alternative network locations. Investigating potential energy storage solutions to store excess electricity generated by your wind or solar farm. AEMO 2018 Questions and Answers 4

5 Remediation works to address system strength limitations at your cost. Configuring the connection to minimise ancillary services constraints. AEMO s preference is for connected parties to be fully switched, but alternatives may be considered in some circumstances. Consider technology outputs (generation sources) which are complementary/ anticorrelated to existing generators. In addition to above, if the outcome of the RIT-T is that the preferred solution does not yield a sufficient net market benefit to warrant an augmentation by the network service provider, you could fund the cost of augmentation or other works by the network service provider to alleviate the network congestion. You should note that if you fund an augmentation to the network for the purposes of your project, exclusive access to the increased network capacity is not guaranteed. What if I need more information? For connection enquires connections@aemo.com.au For RIT-T enquiries planning@aemo.com.au AEMO 2018 Questions and Answers 5