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Get it right this time … testing and rigour will help us build the renewable energy grid we need

The complex make-up of our energy grid is holding back its full potential, writes Mark Andrews. Only an earnest approach to risk mitigation and testing will ensure success of a new, clean NEM.

Australia is in transition. The ways we draw our power have changed so vastly in a relatively short time that our grid infrastructure is being stretched. The traditional model, where we draw the majority of our energy from fossil fuels and natural gas, is evolving. Solar, wind, waves and even hydrogen now make up the energy mix.

While a proactive approach is the right way forward in reducing emissions and ultimately decarbonisation, the fact remains parts of the grid are not yet ready for a mass scale-up to accommodate a large proportion of renewable energy.

As a visual representation, when compared to the maze-like layout of countries such as the US and UK, Australia’s electricity grid is akin to one single thread, connecting the northernmost tip of Queensland around the coast through NSW and Victoria to South Australia and Tasmania, with a few branches reaching out along the way.

The result of this layout is that a serious connection breakdown anywhere can have a sizeable impact thousands of kilometres away. With a government priority being to increase renewable take up, and land acquisition no longer the critical bottleneck, conversations have turned more towards the capability of the grid.  

Primary function

A connected grid must produce energy as its primary function, as well as deliver power at the right voltage and frequency at a local level, usually around 50Hz. It can be a lengthy, complicated process to identify a transmission line that new generation can be connected to, especially with all the different interacting inputs now joining the mix from renewable sources. There is the added risk that these will become too much for the protection systems currently in place to prevent equipment damage – it was mis-specified protection systems that contributed to the infamous 2016 blackout in South Australia.

At the time of the South Australia blackout, wind power was blamed for the outage. Though it was a rare event that even the most thorough simulations were unlikely to have predicted, the issues of our relatively sparse transmission grid had been laid clear for the world to see. Since then, we have witnessed a surge in the demand for rooftop solar and a commitment from the Australian Energy Market Operator (AEMO) to have a grid capable of managing instances of 100% instantaneous penetration of wind and solar generation by 2025.

Let’s take that second point for a moment. An entire country’s grid powered by renewable energy in fewer than four years. It’s hard to imagine that such a feat would be possible, but it is … if some critical steps are addressed first.

At Vysus Group we have repeatedly seen the consequences of errors being made at important steps in the initial planning and development stage, causing delays, financial issues and strained relations with investors.

Interestingly, however, our weak energy grid has resulted in Australia having some of the most stringent connection regulations in the world. A whole raft of potential impacts pertaining to safety and performance are analysed closely at an early stage, yet issues still arise. In fact, many of our clients come to us to resolve issues which may have been prevented with closer insight.

Realistic scenarios

To take a renewable energy project from conception through to construction can be a lengthy procedure. Even at an early stage there is a lot of work going into computer modelling and simulations, the results of which determine whether a project can advance. These involve subjecting the simulation to different energy inputs and disturbances and creating as many realistic scenarios that the grid could encounter based on all current and planned renewable energy sources generating at once.

Using these models and simulations is key for getting a holistic overview. By demonstrating robustness to disturbances at all points on the grid, the simulations unearth solutions that will ultimately improve efficiency and return on investment. And because this happens before spades touch the ground, the scope is there to rectify any complications not previously considered in preliminary consultations. There is already a sizeable backlog of solar projects caused, in part, by this very reason.

To give an example, the Limondale Solar Farm project in West Murray, a notoriously weak part of Australia’s grid, underwent a series of grid-connection studies to support its registration in 2020. Without these, the project would have fallen victim to compliance regulations and costly delays would have been inevitable.

Challenges in weak grids

Perhaps one of the main lessons to take from Limondale, and similar large-solar farms gaining consent on an increasingly frequent basis, is that developers need to be made more aware of, and understand better, the challenges of renewable energy technology in weak grids. Only then will the full potential of what the project can safely and consistently deliver become clearer.

Because our grid was constructed with fossil fuel energy in mind it is not always possible to simply connect and go. There are plenty of other factors to resolve, some possibly not even within 100km of the site. Limited synchronous generation, which AEMO head Daniel Westerman likened to riding a bike “really, really slowly”, is one such issue.   

Synchronous generation, traditionally provided by rapidly spinning machinery but in principle any “stiff” source that can force through the ideal voltage, is needed to keep the frequency where it needs to be and ensure alternating currents are “in synch” across the system. The challenge comes when the destination for those currents is far from the generator, causing a much weaker synchronising signal which the rest of the grid latches onto and moves further out of synch, in the worst case leading to a feedback loop that the grid simply cannot contain.

Viable solutions

The secondary challenge, you may not be surprised to hear, is rectifying this. Technology is already being developed to enable wind and solar inverters (rather than the rotating machinery used in coal and gas plants) to provide “grid-forming” voltage and stability across “normal” and emergency conditions, which would also bring down maintenance costs. But the immediate plan could be to use the US model of repurposing machinery from closing thermal energy plants as synchronous condensers, or the use of batteries, which are now being seen as a solution to energy fluctuations and expanding storage capabilities. Both are viable, though further discussions between developers, regulators and consultants will need to take place before either can be brought out on a mass scale.

Batteries are also being seen as a solution to providing a more continuous flow of energy from a naturally fluctuating source, or conversely, matching the energy flow to a fluctuating load.

The fast uptake of solar and renewables in Australia, roughly 10 times the global average uptake per capita, is a double-edged sword. While we’re absolutely making strides towards our ambition to be a leader in renewable power, we are up against challenges that many other countries are not having to address (yet), especially around stability.

Across Australia, managing the technology shift with renewable energy is a juggling act for which engineers are figuring out solutions.

Mark Andrews is vice-president grid and power systems at engineering and technical consultancy Vysus Group.

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