Short Answer:

FACTS (Flexible AC Transmission Systems) devices help in reactive power compensation by controlling and regulating the flow of reactive power in the power system, ensuring stable voltage levels and improved power transfer capability. They provide fast and precise reactive power support, which is essential for maintaining system stability, especially under varying load conditions.

These devices can both inject or absorb reactive power as needed, using advanced power electronics. By doing this, FACTS devices reduce transmission losses, improve power factor, and support voltage regulation across transmission networks and large industrial systems.

Detailed Explanation:

FACTS devices in reactive power compensation

Reactive power compensation is crucial for the efficient operation of AC power systems. It ensures proper voltage regulation, reduces transmission losses, and improves system stability. FACTS devices are advanced power electronic-based systems developed to provide flexible and fast control over various parameters of the power system, including reactive power flow.

FACTS devices allow dynamic control of reactive power in both generation and load sides without mechanical switching, offering real-time response and enhanced control. They are widely used in modern power grids to support increasing power demand, renewable integration, and voltage-sensitive operations.

How FACTS Devices Help in Reactive Power Compensation:

1. Dynamic Reactive Power Control:
   FACTS devices can quickly inject or absorb reactive power depending on system requirements. This helps in maintaining the desired voltage level at different points in the transmission network.
2. Fast and Continuous Regulation:
   Unlike traditional devices like capacitor banks which are switched in steps, FACTS devices offer smooth and continuous control using thyristors or other power electronic switches.
3. Stabilizing Voltage and Enhancing Power Factor:
   By managing reactive power, FACTS devices help maintain voltage stability and improve power factor, which are critical for minimizing power losses and avoiding penalties in industrial applications.
4. Reducing Line Congestion and Losses:
   Proper reactive power compensation reduces unnecessary reactive current in the line, decreasing I²R losses and freeing up line capacity for real power transfer.
5. Support During Disturbances:
   During sudden load changes or faults, FACTS devices respond instantly to balance the system by adjusting reactive power, preventing voltage collapse or instability.

Types of FACTS Devices Used for Reactive Power Compensation:

1. SVC (Static VAR Compensator):
   Controls reactive power using thyristor-switched capacitors and reactors.
2. STATCOM (Static Synchronous Compensator):
   A voltage source converter-based device that provides faster and better voltage support than SVC.
3. UPFC (Unified Power Flow Controller):
   Can control active and reactive power flow and maintain voltage by adjusting reactive injection at multiple points.
4. TCSC (Thyristor Controlled Series Capacitor):
   Used in series with the line to dynamically control line reactance and improve reactive support.

Applications of FACTS in Reactive Power Management:

• Long transmission lines with voltage drop issues
• Wind and solar power integration sites
• Urban load centers with rapid demand changes
• Industrial plants requiring power quality improvement

Conclusion:

FACTS devices help in reactive power compensation by offering fast, controllable, and reliable management of reactive power in AC systems. They enhance voltage stability, improve power transfer capacity, reduce losses, and enable efficient operation of modern, dynamic power networks. Their role is becoming increasingly important with the rise of renewable energy and demand for grid flexibility.