AdvancedTopic 106 of 106Electrical Engineering
Grid-forming inverters
Inverters that set voltage and frequency, enabling grids with high renewable share.
In depth
Grid-forming inverters act as voltage sources, establishing frequency and voltage reference rather than following the grid with a PLL. They provide synthetic inertia and black start, and operate in weak grids or islands. Control methods: droop, virtual synchronous machine, matching control.
Key points
- Needs energy reserve
- Current limiting in faults
- Essential for 100% inverter-based grids
ExampleA battery inverter can restart an island microgrid without any synchronous generator.
What is Grid-forming inverters?
Inverters that set voltage and frequency, enabling grids with high renewable share.
Why is it important to understand grid-forming inverters?
Grid-forming inverters set voltage and frequency themselves rather than following the grid, which is needed as conventional generators are replaced.
What is the difference between grid-forming and grid-following inverters?
Grid-following inverters need a grid voltage to synchronise to, while grid-forming inverters create the voltage and frequency, which allows them to operate in islands.
Why do grids need grid-forming devices?
Traditional synchronous generators provide inertia and voltage support, and inverters must replace these functions as they become the main source.
How is Grid-forming inverters used in practice?
Typical applications include supplying a weak grid with high solar penetration that needs voltage support, running an islanded microgrid that has no synchronous machines and providing inertia-like response in a battery storage plant.
What should I learn before Grid-forming inverters?
Study "Power quality and harmonics" first (topic 105 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
What are the key points of Grid-forming inverters?
Needs energy reserve. Current limiting in faults. Essential for 100% inverter-based grids.
Can you give an example of Grid-forming inverters?
A battery inverter can restart an island microgrid without any synchronous generator.
What comes after Grid-forming inverters?
This is the final topic in Electrical Engineering.
How difficult is Grid-forming inverters?
It is classed as Advanced in Electrical Engineering (topic 106 of 106). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Electrical Engineering.