Principles_of_Reactive_Power_Control.pptx

Principles of reactive power control in power systems

1. Principles of Reactive Power Control

2. Introduction Reactive power (Q) is essential in AC systems for sustaining voltage levels. Unlike active power, it does not perform useful work but supports electromagnetic fields. Effective control ensures voltage stability, efficient power flow, and reliability.

3. Maintain Voltage Magnitude Voltage and reactive power are tightly coupled. Reactive deficit → voltage drops; excess → over-voltage. Control principle: keep bus voltages within ±5%. Methods: AVR, OLTC, capacitor/reactor switching, FACTS devices.

4. Local Compensation of Reactive Power Reactive power cannot be transmitted efficiently over long distances. Principle: Generate/absorb reactive power locally near the load. Minimizes line losses and congestion. Example: Capacitor banks at substations.

5. Minimization of Transmission Losses Excessive reactive current increases I²R losses. Proper balance reduces current magnitude and improves efficiency. Compensation techniques: shunt capacitors, FACTS controllers.

6. Improving System Stability Steady-State: Reactive support ensures stable voltage. Transient: Fast-acting devices prevent voltage collapse. Dynamic voltage control maintains generator synchronism.

7. Reactive Power Sources & Absorbers Synchronous Generators (excitation controlled). Capacitor Banks & STATCOMs (supply reactive power). Shunt Reactors (absorb excess power). Synchronous Condensers (dynamic continuous support).

8. Static vs Dynamic Reactive Control Static Devices: Capacitors, reactors, OLTCs (economical, slower). Dynamic Devices: SVC, STATCOM, synchronous condensers (fast-acting). Principle: Use a mix for economy + reliability.

9. Excitation System and AVR Control AVRs adjust excitation to regulate generator reactive output. Over-excitation → supplies reactive power. Under-excitation → absorbs reactive power. Ensures generator bus voltage control.

10. Coordination of Resources Multi-level coordination: - Generation: Excitation control. - Transmission: Shunt devices, FACTS. - Distribution: Capacitor banks, OLTCs. Ensures balanced support, reduced losses, system reliability.

11. Summary Maintain voltage profile. Supply reactive power locally. Reduce losses. Improve system stability. Balance static and dynamic compensation. Coordinate across all system levels.

12. Schematic diagram of P–f controller and Q–V controller