When most people think of capacitors, they envision the tiny ceramic devices that are ubiquitous in the printed circuit boards of electronic products of all kinds. However, there is a different breed of capacitor out there—a hulking device designed for power factor correction (PFC) in large-scale electricity transmission applications.
Power Factor Correction Capacitors
These high-voltage capacitors play a key role in the electricity grid, performing functions that can improve the efficiency, capacity and stability of power supply systems. Furthermore, as part of smart grid systems, such capacitors can reduce the amount of carbon emissions required to generate power for electrical grids and help integrate renewable sources into the power system.
Such capacitors are often sold as banks, i.e. arrays of capacitors that are connected to a circuit. Instead of the farads usually used to classify small capacitors, these large power capacitors are valued based on their volt-amperes reactive (var) capacity.
These banks often come in sets of three capacitors. Larger sets of capacitors can be installed in large utility substations. One promising area for power capacitors usage in electrical generation is the flexible AC transmission system (FACTS).
(FACTS) Flexible AC Transmission System
FACTS is a key enabler of the smart grid, allowing utilities to reconfigure the flow of power as needed. This capability can maximize throughput and reduce losses. FACTS also makes it possible to integrate into the grid intermittent power sources, such as wind and solar.
The global FACTS market is expected to expand to $1.4 billion by the end of 2018, up from $912.9 million in 2012, according to Research and Markets. FACTS demand is expected to be driven by the increasing integration of renewable sources in regions including Europe.
Electric utilities accounted for more than 70 percent of the overall FACTS market in 2013. The steel and mining industries were the next largest segments for FACTS.
Using Capacitors for Power Factor Correction
FACTS uses capacitors to perform PFC, managing the negative reactive power that naturally occurs when electricity flows through transformers and generators. Excess negative reactive power can damage electrical equipment, potentially leading to major power failures. Capacitors can compensate for this negative reactive power by adding positive reactive power into the system.
Examples of companies serving this market include Eaton, which offers lines of capacitors targeting FACTS. These families offer solutions up to 15kV and are optimized for various situations, like a dynamic power factor or high EMI environments.