Revitalising the grid with solar energy

Solar energy, a renewable energy sourced directly from the sun, is a popular source of power for homes, buildings and cities. For bigger energy needs, large-scale photovoltaic (PV) systems, also known as solar parks, are designed to produce solar energy and supply power into the electricity grid.

Dr Ricardo Aguilera from UTS’s School of Electrical and Data Engineering and Dr Javier Pereda from the Faculty of Engineering at Pontifical Catholic University of Chile (UC) design PV systems that can support the electricity grid in ways that are more efficient. Since PV systems cannot produce solar energy at night, the two academics have come up with a way for PV systems to support the electricity grid when there is no sun.

“The power converter can do something that is called grid supporting. It can support the grid but not in terms of solar energy, it can help to keep the voltage level in the right value. This is called reactive power, it is the kind of power that is injected into the grid but then passed back to the power converter very quickly,” Dr Ricardo Aguilera said.  

The Australian Energy Market Operator (AEMO) regulates the electricity grid and sets the standard for the level of voltage that is safe for the electricity grid to operate. By injecting reactive power into the grid and then returning that power to the PV system, the overall voltage of the PV system is boosted and is kept within the AEMO standards.

“At the moment, PV systems are not allowed to support the grid. But we are using our research to show that PV systems have the potential to do it, especially at night because PV systems are not being used at night,” Dr Ricardo Aguilera said. 

The two academics are also working on finding ways to improve the efficiency of PV systems when the sun goes behind a cloud and there is partial shading of a section of the system. 

“When you have a big plant, over a large extension of land, then the clouds can cover part of that. And then you have a problem.” Dr Ricardo Aguilera said. 

This is due to the PV system being connected to the electricity grid at different sections. The AEMO  states that a PV system cannot inject different levels of power to the electricity grid; instead, it must inject the same amount of power at all sections. 

“So the question is how can we extract the maximum available power of the whole thing? We are experimenting with taking all the power of the system, rearranging it and sending it equally to all the sectors. We need to redesign the power converter and consider how it can optimally handle this task.” Dr Ricardo Aguilera said.

UTS and UC have a strong partnership; the two institutions agreed to co-fund Dr Javier Pereda’s visit to UTS for two weeks under the KTP Visiting Fellow Program. For Javier, there was value in working face-to-face with Ricardo to further their research and to meet faculty counterparts in UTS’s School of Electrical and Data Engineering.

“I think it is very important to know how UTS works, its facilities, laboratories and know the academics and staff in person to enhance the collaboration. My visit was very useful and reinforced our collaboration.” Dr Javier Pereda said.

Since Dr Javier Pereda has returned to UC in Chile, the two academics plan to enhance their collaboration through the co-supervision of PhD students.

“We want to create a bridge between both universities for postgraduate students to be involved in our sustainable collaboration over time.” Dr Ricardo Aguilera said.