Power Factor Correction System - Electrical Engineering Guide
1. Introduction
A Power Factor Correction (PFC) System is designed to improve the power factor of an electrical system by reducing the phase difference between voltage and current. It increases energy efficiency and reduces power losses.
2. Objectives
• Improve system efficiency
• Reduce electricity bills
• Enhance power quality
• Minimize reactive power usage
3. System Overview
The system monitors the power factor and dynamically switches capacitors in or out of the circuit to maintain the desired power factor level close to unity.
4. Components Required
• Microcontroller (optional, e.g., Arduino or PIC)
• Current and voltage sensors
• Capacitor banks
• Relays or solid-state switches
• Power supply unit
• Display unit (LCD or LEDs)
• Protection fuses
5. Block Diagram and Operation
The block diagram includes voltage and current sensors, power factor calculator, controller logic, and relay-controlled capacitor banks. The controller continuously monitors the power factor and compensates as needed.
6. Types of Power Factor Correction
• Passive PFC: Uses capacitors or inductors.
• Active PFC: Uses power electronics to shape the current waveform.
• Automatic PFC: Uses microcontroller to switch capacitors automatically.
7. Circuit Design and Control Logic
Design the sensing circuit using current transformers and voltage dividers. Use zero-crossing detectors to calculate the phase difference, and switch capacitors using relays to correct the power factor.
8. Role of Microcontroller (if used)
The microcontroller samples voltage and current signals, computes the power factor using algorithms, and actuates relays to connect/disconnect capacitors based on the correction needed.
9. Capacitor Bank Design
Calculate the required kVAR for correction. Choose appropriate capacitor ratings and group them in banks that can be switched independently to match varying loads.
10. Implementation Steps
1. Design and test sensor and measurement circuits
2. Program microcontroller for power factor calculation
3. Design switching logic and relay drivers
4. Assemble and test the complete setup
11. Safety Considerations
• Use proper fuses and circuit breakers
• Isolate low-voltage and high-voltage sections
• Include surge protection
• Discharge capacitors safely before maintenance
12. Testing and Results
Test under different inductive loads. Measure the improvement in power factor before and after correction using a power analyzer. Ensure switching is timely and reliable.
13. Applications
• Industrial plants with large motors
• Commercial buildings
• Power distribution systems
• Renewable energy systems
14. Advantages and Limitations
Advantages:
• Improved energy efficiency
• Reduced energy costs
• Better voltage regulation
Limitations:
• Initial cost
• Requires monitoring system
• Sensitive to load changes
15. Cost Estimation
• Capacitor banks: $20–$50
• Microcontroller and sensors: $15–$30
• Relays and control: $10–$20
• Total: $50–$100
16. Future Enhancements
• Add IoT interface for remote monitoring
• Use ML algorithms for predictive correction
• Incorporate harmonic filtering
• Use thyristor-switched capacitors for speed
17. Conclusion
Power Factor Correction is a key technology for efficient power management. By dynamically compensating for reactive power, it improves power quality and reduces costs.