Chile’s grid coordinator CEN issued a regulatory recommendation to the energy ministry concerning grid-forming technology.
In a letter to energy minister Diego Pardow, CEN board chief Juan Carlos Olmedo said future solar and wind plants – along with battery, HVDC and Statcom systems – should be capable of operating in grid-forming mode (GFM).
Depending on the result of specific requirement studies, existing assets could also be potentially subject to the proposed measure. Permitting asset owners to adopt the technology is also suggested.
Adoption of grid-forming technology is seen as a way to support the ongoing decarbonization of the grid, given such solutions can mimic the behavior of traditional synchronous machines, such as those incorporated into thermoelectric power plants.
“Operation in GFM permits inverter-based generation resources to actively contribute to the stability and control of the electricity network, particularly in the event of disruptions, voltage drops, massive disconnection events or formation of islands,” Olmedo wrote.
Globally, grid-forming technology is in the early stages of adoption, with SMA, Siemens Energy, Huawei, Kehua, Hitachi Energy, General Electric, Schneider Electric, ABB, Fimer Group, Sungrow Wind and Power Electronics among actors on the supplier side.
The market is expected to grow apace over the coming years as wind and solar penetration grows globally. Chile’s fleet of wind and solar parks has expanded rapidly against the backdrop of a drive to retire or convert, by 2040 at the latest, around 5.5GW of coal-fired generation capacity. An associated country goal is achieving an emissions-free grid.
CEN, which has been carrying out grid-forming technology testing work at its research laboratory, has put out to consultation associated technical standards.
“Incorporation of these technical standards will permit advancement toward a more resilient, flexible and secure electrical system, in line with international regulatory experience, such as initiatives adopted in Australia, Europe and the US in this area,” Olmedo wrote.
CEN is part of G-PST, a global consortium that brings together a network of stakeholders to accelerate technical solutions that enable grids across the world to run on 100% renewables energy.
To find out more, BNamericas conducted an email interview with Ricardo Álvarez, an energy systems researcher at Chile’s solar energy research center SERC and academic at Universidad Técnica Federico Santa María.
Detailing the technical differences between grid-following mode – the most widely adopted today by generation technologies that connect to the grid via a converter, such as solar, wind and batteries – and GFM, Álvarez said: “In this context, implementation of this operation mode in Chile could significantly contribute to the decarbonization process of the electrical system, allowing for an increase in the penetration of non-conventional renewable energies while maintaining the security and stability of the system.”
He added, “however, we must be cautious when integrating this type of technology. There are still only a few countries that have adopted it, and with specific projects.”
BNamericas: When we talk about grid-forming technology, are we referring to software, hardware or both?
Álvarez: Grid-forming technology refers to both software and hardware. The hardware consists of the converters, which are devices that control the voltage and frequency, and the sensors and measuring equipment, which monitor the grid conditions and adjust the control parameters. The software consists of the control algorithm implemented to regulate the voltage and frequency.
BNamericas: Are other countries adopting grid-forming technology? And is there any country that could serve as a model for Chile?
Álvarez: Several countries have implemented grid-forming technologies, such as Australia, the United Kingdom, Canada, the United States and Scotland.
However, this technology has not yet been implemented on a massive scale. Most of the projects consist of batteries operating in grid-forming mode: in Australia, in 2020, a 150MW battery was adapted to operate in grid-forming mode as part of the Hornsdale Power Reserve project; in the United Kingdom, in 2022, as part of the Pathfinder project, five batteries were installed to operate in grid-forming mode.
There are also examples of renewable energies with converters operating in grid-forming mode: in Scotland, in 2021, as part of the Dersalloch wind farm project, a 69MW wind farm was implemented with grid-forming technology. The particularity of this project is that it allows part of the system to be re-energized in the event of a blackout.
These projects have demonstrated that grid-forming technology is capable of operating adequately in power systems, even improving system stability. In Chile, we can learn from this experience, see what technical challenges they have faced, how they have dealt with them, and also see how they have adapted their technical standards to safely integrate this type of technology.
BNamericas: What are some of the technical, economic or other challenges of using this technology?
Álvarez: Although grid-forming technology has already been successfully implemented in power systems, there are several challenges, especially when considering large-scale integration into electrical systems.
For example, coordinating multiple converters can be complex. If the controller parameters are not well-defined, undesirable interactions between controllers can occur, causing oscillations or, in the worst case, instabilities. Another challenge is that grid-forming technology does not provide the natural inertia to the system, as synchronous generators do.
This means that, in the case of a large power imbalance – for example, the failure of a generation unit – the frequency will drop abruptly in a very short period of time, potentially triggering protection schemes for rate-of-change-of-frequency. While there are control schemes to emulate the inertial response of synchronous generators, it is not the same.
Another challenge of employing grid-forming technology on a large scale arises from the limited contribution to fault currents from this technology – 1 to 2 times its nominal current – compared to the fault currents provided by synchronous generators – 5 to 10 times their nominal current.
When a short circuit occurs, many protections require high fault currents to detect and isolate the fault. In this context, if the fault currents are very low, for example, if there are few synchronous generators operating near the fault, traditional protection schemes may not detect the fault or isolate it in time.