Overcoming ambiguities when connecting renewable assets to the grid

Major rule changes to the grid connection process, which came into effect in 2018, have been keeping Aydin Kizilirmak, from Potentia Energy, on his toes.

As Head of Grid Connection and Approvals, Aydin helps design renewable asset projects – a lengthy and complex process involving power system analysis, connection studies, and compliance monitoring. Environmental and ecology studies are also under his remit.

While the requirements for connecting to the grid are now clearer, they are still open to interpretation – and without the right support, challenges can emerge in the delivery phase, he says.

“There has been a big jump in the amount of studies required, including EMT studies, detailed analysis, and benchmarking between various software, like PSSE and PSCAD.

“These new software requirements have brought in quite a large spectrum of workloads and industry rules in terms of design,” he said.

Historically, these rules were mainly for scheduled assets like gas generators, but with electronic devices, like asynchronous generators, the results – and how they interact with the network – are significantly different. That has brought ambiguity to the rules and different approaches from one NSP to another one or AEMO.

Adding to that, there are varying responsibilities across jurisdictions and authorities in terms of voltage levels, depending on where the project is located. Project’s proponents may have to respond differently if they are close to a mine, or if they are operating at a very low or strong SCR (Short Circuit Ratio).

“The rules didn’t really capture how to approach these differences relating to points of connection, when they covered automatic access standards. So, this has created some challenges for certain projects.

“For example, if you are close to a mine, you might not necessarily want to inject more iq – it could be too much already. But, the rules weren’t really prescriptive in all of the impacts. Likewise, if a project operates at a very low or very high SCR, the responses could be significantly different and so could be the requirement.”

Software limitations

Digging deeper, there are also some technical considerations, relating to software limitations. Failing to acknowledge these early in the design process could cause project challenges later on, Aydin warned.

“For example, proponents need to consider whether it’s an artifact of the model or it’s an actual performance, which was difficult to validate. It requires extensive modelling which brings additional costs but especially time impact to project targets. These limitations have stalled projects, especially if they were identified during the construction phase, and the contracts were already entered into. Some have created damages and even bankruptcy.”

These bankruptcies have prompted improvements across the industry. Consultants now tend to work on the connection phase before projects go into construction, and there have been technical updates to various software.

“We’ve seen quite a few model updates, along with model acceptance testing and improvements on how they are presented. These lessons have improved the connection from being purely focussed on power system analysis, to also include infrastructure.

“Most of the NSPs have started looking into grid improvements, strengthening the infrastructure via various commitments, most of it captured under AEMO’s Integrated System Plan (ISP) which is a roadmap for the transition of the National Electricity Market (NEM) power system, with a clear plan for essential infrastructure. Further planning with wider industry collaboration is actively progressing.

Along with the introduction of renewable energy zones, projects now have a more streamlined connection. But there are still lingering technical hurdles.

“You still need to navigate how the harmonics are managed, how the system strength is managed, how the technology within the zone is divided, or whether type of functionalities like grid forming technology or virtual synchronous condensers and so on is applied.”

Further, technical solutions still need to be agreed in commercial contracts, with details on operational ownership of the asset.

“All that can take some time to negotiate, and different approaches can certainly impact the modelling. The key is to get an early design for a project facing these issues. So, we try to work with our consultants – and ideally with contractors – in an early contractor involvement phase, to enable basic design to progress.

“It’s a 30 percent design level, prior to kicking off approval and connection process, which allows us to minimise the changes throughout the project.
“Once we have contractors on board to deliver the project, it ideally has its approvals already, and doesn’t need to go through additional model analysis. The best outcome is when there is a match at testing phase to what was modelled on the desktop.”

Hardware considerations

Testing requirements involving hardware have also been complex to navigate, Aydin said.

“Two years ago, only one or two were going ahead with a hardware in the loop test, but it’s almost a mandatory activity now for almost every project.

There are considerations around network analysis that involves not just a typical load flow analysis, but market modelling and congestion analysis. Also, what the future network upgrades look like and what type of advanced grid forming technologies might be required.”

Working with the NSP for bilateral contracts is also a key factor.

“We are trying to match our market understanding with the power system. Market modelling and power system should always go hand in hand. A particular location might be feasible for a certain technology – for example, in Queensland we know the wind requirements are especially high while system strength charges are also higher than the other states. So, a grid forming wind turbine in Queensland is a lot more feasible application compared to South Australia.

“This is best considered early on, so that the remaining phase of the projects are a lot smoother.”

Further commentary

Sharing further best practice on grid connection, Aydin Kizilirmak will present at the upcoming Australian Renewable Energy Zones Conference hosted by Informa.

This year’s event will be held 21-22 May at the Swissotel Sydney.

Learn more and register your tickets here.

About Aydin Kizilirmak

Aydin Kizilirmak has been Head of Grid Connection and Approvals for Potentia Energy (formerly Enel Green Power Australia) since 2019. Across Aydin’s eight year career in the renewable sector, he has actively contributed to more than twenty constructed Wind/Solar/storage projects, totalling over 2GW, plus numerous developing projects. He is enthusiastic about reaching net ZERO targets and making the grid 100 percent renewable.