Grid-enhancing technologies (GETs) — such as systems that control power flow and equipment that supports voltage and stability — help utilities boost capacity, improve voltage stability and avoid delays associated with building new transmission lines.
These are tools that strengthen grid reliability and support the transition to low-carbon energy.
As the grid becomes more dynamic and decentralized, technologies like shunt-connected Flexible AC Transmission Systems (FACTS) and synchronous condensers (SYNCONs) are becoming essential. These tools help ensure voltage stability, improve power quality and enable more reliable energy. Their ability to deliver fast, flexible support makes them a cornerstone of modern grid planning.
With the U.S. power grid evolving to accommodate more renewable energy and electrification, maintaining voltage stability and power quality is increasingly complex. Aging infrastructure, the retirement of thermal power plants and growing demand from homes and industries are straining the system. To address these challenges, utilities are turning to advanced technologies like FACTS and SYNCONs.
What are FACTS and SYNCONs?
FACTS devices are power-electronics-based systems that enhance grid performance. They come in two main types:
- series-connected to manage power flow, and
- shunt-connected to regulate voltage and provide dynamic reactive power.
Shunt-connected FACTS devices, such as static synchronous compensators (STATCOMs) and static var compensators (SVCs), offer several advantages for reactive power compensation and voltage support. They provide extremely fast response times — on the order of milliseconds — and allow for precise, continuously adjustable reactive power control.
Their modular and compact design makes them suitable for installations with limited space, and the absence of rotating parts reduces mechanical maintenance needs. Additionally, STATCOMs can support grid stability by offering limited short-circuit current and voltage ride-through capabilities, which is particularly useful for renewable integration.
SYNCONs, on the other hand, are rotating machines that offer similar voltage support while also contributing inertia and short-circuit strength — critical for grid stability.
“Synchronous condensers are key components that provide inertia and fault current to the grid,” explains Chris Postma, senior system planning and resiliency advisor at WSP in the U.S. “They serve as a grid reference for inverter-based resources — like most modern wind installations — which rely on that reference to operate effectively. Strategically placing these devices based on local grid needs can significantly enhance the stability and reliability of renewable energy systems.”
What’s your system priority?
SVCs, STATCOMs and SYNCONs are all used in transmission systems to regulate voltage, improve transient stability, enhance fault recovery and increase power transfer capacity. However, they differ in several key aspects.
- Synchronous condensers uniquely provide inertia and short-circuit current. These features make them especially valuable for grid stability in systems with high levels of inverter-based resources. In contrast, SVCs and STATCOMs do not inherently provide these benefits, though STATCOMs can offer them when designed with grid-forming and energy storage capabilities.
- Response speed varies. STATCOMs are the fastest (1.5–2 cycles), followed by SVCs (2–3 cycles), while synchronous condensers are slower (20–30 cycles). STATCOMs also offer the most flexible reactive power capability, delivering 100 percent inductive and capacitive support; synchronous condensers typically provide 50–60 percent inductive and 100 percent capacitive.
- Efficiency differs under low-voltage conditions. All three technologies experience reduced voltage support as system voltage drops, but STATCOMs are more efficient, with lower losses both at no-load and full-load conditions. Synchronous condensers, while effective, have the highest losses and moderate maintenance costs.
- Installation requirements vary. STATCOMs and synchronous condensers require less space than SVCs. STATCOMs also typically operate at higher voltages (20–70 kV), while SVCs and synchronous condensers operate in the 10–40 kV and 13.8–25 kV ranges, respectively. Additionally, SVCs require harmonic filters, whereas STATCOMs and synchronous condensers generally do not.
The choice among these technologies depends on system needs — whether the priority is fast response, voltage support, inertia or space and efficiency considerations.
