What is a STATCOM (Static Synchronous Compensator) and how is it used in HVDC GRID applications?
The STATCOM is ubiquitous in grid applications.It is a power electronics-based device used in electrical transmission systems to manage reactive power and stabilize voltage on the grid. At its core, a STATCOM is built from high-power IGBT modules arranged in a voltage source converter (VSC) topology. An example is a 6 level converter in which each level utilised optimised IGBTs as supplied by Dynex.
How a STATCOM works
The STATCOM connects to the AC power network through a transformer. It uses a DC capacitor as its energy source and IGBT converters to generate an AC voltage waveform in real time. By controlling this AC voltage’s magnitude and phase, the STATCOM can inject or absorb reactive power from the grid.
In the capacitive mode, a STATCOM works by injecting reactive power (leading current) and this raises the grid voltage. And, in the inductive mode, a STATCOM absorbs reactive power (lagging current), thereby lowering the grid voltage.
This dynamic control happens within milliseconds, much faster than traditional systems like synchronous condensers or mechanically switched capacitors.
Role of STATCOM in HVDC and Grid Applications
In HVDC (High Voltage Direct Current) transmission and other modern power grids, STATCOMs play several essential roles.
HVDC converter stations (which convert between AC and DC) can cause voltage fluctuations and reactive power imbalances. A STATCOM at each terminal will help maintain stable AC voltage, compensate reactive power demand of converters and enable smooth operation under varying load and fault conditions.
In long HVDC or weak AC networks, fast voltage changes can occur due to line energisation, fault recovery or load switching. In these situations, a STATCOM will provide instantaneous reactive power to reduce these oscillations and prevent voltage collapse.
By stabilising voltage and reactive power, STATCOMs allow more active power transfer through existing lines without increasing current or risking instability. This means better utilisation of transmission assets.
STATCOMs also work to improve fault ride-through capability of HVDC converters, mitigate flicker and harmonic distortion, and support grid restoration after outages.
Why IGBT-based STATCOMs are important
Modern STATCOMs are typically built using high-voltage IGBTs arranged in modular multilevel converter (MMC) configurations providing high efficiency, low harmonic distortion, compact designs and fast response times.
Dynex supplies high-voltage, high-current IGBT modules (up to 6.5 kV) that are ideally suited for these converter designs in both STATCOM and HVDC systems. Our standard and custom IGBT modules are optimised for thermal performance, switching efficiency, and long service life. Rugged IGBT designs proven in rail, renewable energy, and industrial systems.
Contact us to discuss how we can support your Power Solutions projects