Reactive Power (VAR) Compensation: In AC systems, capacitors provide leading reactive power (VARs) that cancels out the lagging VARs from inductive loads (motors, etc.), thereby boosting voltage levels and improving power factor.
Voltage Stabilization: They absorb excess current when voltage rises and release it when voltage drops, keeping levels more constant and preventing sags and swells, especially with fluctuating renewable sources like solar/wind.
Temporary Power Backup: A capacitor can power equipment for brief moments during a start-up or short interruption by discharging its stored energy, preventing system resets.
Harmonic Filtering: Capacitors can be combined with reactors (inductors) to create filters that absorb unwanted harmonic frequencies, preventing voltage distortion and equipment overheating.
Applications
Power Grids & Substations: Large capacitor banks stabilize transmission and distribution networks, ensuring reliable power delivery.
Renewable Energy: Smooths the variable output from wind turbines and solar farms, integrating them seamlessly into the grid.
Industrial Facilities: Correct power factor to avoid penalties and reduce energy costs.
Electronics: Small capacitors on circuit boards filter noise and provide stable power for sensitive components.
Types
Capacitor Banks: Assemblies of multiple capacitors for large-scale applications (utility-grade).
Shunt Capacitors: Connected in parallel to supply reactive power.
Series Capacitors: Placed in series to improve voltage profile on long transmission lines.
Surge Capacitors: Designed to protect against transient voltage spikes.