The LABS
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The LABS

Heart Pumps and Power Networks: Engineers Get Global Recognition

While they seem a world apart, heart pumps and national power networks share something in common: power electronics. The QUT researchers advancing new and improved systems are now named among the best in the world.

Professors Gerard Ledwich and Mahinda Vilathgamuwa were named 2020 Fellows of the IEEE — the world’s largest technical professional organisation dedicated to advancing technology for the benefit of humanity.

Professor Ledwich is known for his contribution to managing electricity in the National Energy Market. His latest work facilitates more renewables into grids now and a safer transition to expanded use of renewables in the future.

Professor Vilathgamuwa is known for his work on power quality and grid storage. He says his most impactful research is towards wireless power transfer (WPT) systems to power heart pumps, which reduces the risk of infection.

Both researchers focus on power network details because small mistakes can turn issues into catastrophes.

National power network management and clean energy integration

Professor Ledwich is a principal research fellow in power engineering at QUT and was elevated to IEEE Fellow for his development of control and power systems, and power electronics.

His two main contributions include the monitoring and synchronisation of generators — vital to stable power transmission in Australia — and control over inverters that integrate new energies like solar and wind power into traditional coal-fired power systems.

Professor Ledwich developed a system to monitor and synchronise generators, making sure that they maintain the perfect frequency to hold a safe and steady power supply.”

“Monitoring and synchronisation of the power system basically holds the supply to the nation together.

“Generators all have to stay at 50 hertz. The processes between them make them wobble like a mass and spring, which affects this frequency.

“Queensland sends up to 1200 Megawatts of power to New South Wales. Excess current is produced if generators aren’t synced, and if you let that go it would burn the transmission line to the ground.

“Protection systems prevent that from happening by opening circuit breakers. If those open, New South Wales will be short of power and a lot of customers will be in blackouts.”

Professor Ledwich has a paper ready which he hopes will convince policymakers that improvements in synchronisation are also useful for integrating more renewables with traditional supplies.

Issues with solar integration in north-west Victoria tell the story well.

At high output, solar and wind farms in Victoria have started to oscillate, which has potential to lead to dangerous operation, opening circuit breakers to protect the system and resulting in customers without power, according to Professor Ledwich.

“We want to know why this is happening and how we can improve the system to convince operators not to shut down the renewable energy generators, but instead use a different control mechanism.

“There is currently no solution offered about the oscillation in the north-west Victoria power plant aside from not generating as much solar — telling renewable energy plants to shut down — which is a waste of communal resources.”

“But you can have them all operating side-by-side as long as you have a more integrated view of how each reacts.

“Better performance of synchronised generators means we can incorporate more cleanly the supplies from solar and wind farms into the same power system as traditional generation.”

Solving new energy integration into traditional power systems

Integration issues of renewables and inverters led Professor Ledwich to the second area of contribution to electrical engineering acknowledged by the IEEE.

Professor Ledwich is also researching ways that improved synchronisation can help integrate more renewables into the grid. The existing power network was made for coal-fired energy sources, and renewable energies need to be integrated properly by control systems to keep the grid working as expected.

He developed a suite of tools for analysis and control design of inverters that support renewable energy integration with traditional coal-fired systems.

If managed well, Professor Ledwich says the system could handle 20% more renewables with the same infrastructure.

“All renewable plants are power electronic-based, and if all of these new energy sources — solar on your roof, solar farms, wind farms — try to integrate with conventional systems, then we need better control over inverters.

“Inverters can hold the power system together, keep the generator angles managed, handle emergencies and limit the impact of loss of generation.”

Professor Ledwich’s analytic tools help make sure the power system has superior performance for higher renewables than is currently permitted by the grid operators.

He has demonstrated the tools in the lab but needs funding to test in the field.

“Putting new controls into an existing system will take time. If there were a concerted effort, it would take six months to demonstrate the tools and three years for a complete rollout.

“The transition to 100 per cent renewables would be further along the curve and we would be ready earlier.

“We are changing the system at a cost of tens of billions, but if not managed well it would cost more along the way and the risk of blackouts would be much higher.”

Heart pumps with wireless power transfer to reduce infection and save more lives

Weighing risks against system performance is something Professor Vilathgamuwa is also working towards.

Professor Vilathgamuwa was elevated to IEEE Fellow for his contribution to power quality and grid storage. He is also advancing wireless power transfer (WPT) systems for both dynamic and implanted systems and lithium-ion battery modelling and control.

Working with the Prince Charles Hospital Foundation, in 2017 Professor Vilathgamuwa and his team co-developed a new wireless system to power heart pumps that could save lives. It works by reducing deadly infections caused by current ventricular assist devices (VAD) — mechanical heart-support devices that help patients’ hearts to keep pumping.

It replaced the power cable that would usually go through the skin from an external battery, worn in a holster, to the VAD implanted in the heart.

The new wireless system used a small copper coil receiver which would be implanted inside the body, with a transmitter and battery worn in a holster or a jacket.

Greater efficiency and reduced risks

In tests, the system achieved 94 per cent efficiency in powering a commercial heart pump, without the need to break the skin for a cable.

“The heart pump research is going well. We have been developing necessary hardware for wireless communications between the heart pump and the external controller,” Professor Vilathgamuwa said

“Also, one of my PhD students has been working on robust control techniques and new circuit topologies for the heart pump wireless power transfer.”

Once robust control and wireless communications are implemented, the research team intends to test the prototype using a mock circulation loop stationed at the Prince Charles Hospital Innovative Cardiovascular Engineering and Technology Laboratory (ICETLAB).

“Success of these tests will lead to animal tests in the future,” Professor Vilathgamuwa said.

“I have embarked upon significantly novel developments in WPT systems and control of lithium-ion battery storage systems, which I believe will result in increased citations and industrial collaborations in years to come,” he said.

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