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The 4 quadrants of reactive power refer to the different combinations of active (real) power (P) and reactive power (Q) flow in an AC electrical system. These quadrants are defined based on whether power is being generated or consumed and whether the system is supplying or absorbing reactive power.
The quadrants are categorized based on the sign of P (active power) and Q (reactive power):
| Quadrant | Active Power (P) | Reactive Power (Q) | Description |
|---|---|---|---|
| Q1 | + (Consumed) | + (Lagging, Inductive) | Load absorbs both active and reactive power (e.g., induction motor). |
| Q2 | - (Generated) | + (Lagging, Inductive) | Source supplies active power but absorbs reactive power (rare, but possible in some generator conditions). |
| Q3 | - (Generated) | - (Leading, Capacitive) | Source supplies both active and reactive power (e.g., inverter-based generation with capacitive support). |
| Q4 | + (Consumed) | - (Leading, Capacitive) | Load absorbs active power but supplies reactive power (e.g., over-excited synchronous motor or capacitor bank). |
Active Power (P): Represents real power (kW) flowing to or from a device.
+P: Power is consumed (e.g., motor).
-P: Power is generated (e.g., solar inverter).
Reactive Power (Q): Represents power oscillating between source and load (kVAR).
+Q: Inductive load (lagging current, absorbs reactive power).
-Q: Capacitive load (leading current, supplies reactive power).
Q1 (P+, Q+): Common for industrial motors, transformers.
Q4 (P+, Q-): Over-excited synchronous motors, capacitor banks.
Q3 (P-, Q-): Grid-supporting inverters (PV/wind farms supplying VArs).
Q2 (P-, Q+): Rare, but possible in some generator conditions.
Lagging PF (Q1): Inductive load (e.g., motors).
Leading PF (Q4): Capacitive load (e.g., capacitors).
Unity PF: Purely resistive load (Q=0).
Understanding the 4 quadrants of reactive power helps in analyzing power flow, designing compensation systems (e.g., SVG/STATCOMs, capacitor banks), and ensuring grid stability. Modern power electronics (like inverters) can operate in all four quadrants to provide dynamic reactive power support.
Static Var Generator use voltage-source converters (VSCs) with IGBTs to generate or absorb reactive power dynamically. They can operate in all four quadrants of the P-Q plane, making them ideal for modern power systems with renewables, industrial loads, and grid support.
| Quadrant | Active Power (P) | Reactive Power (Q) | SVG Operation | Application Example |
|---|---|---|---|---|
| Q1 | + (Consumed) | + (Inductive, Lagging) | Absorbs Q (acts like an inductor) | Compensating excess capacitive VARs |
| Q2 | - (Generated) | + (Inductive, Lagging) | Supplies P, absorbs Q (rare) | Regenerative braking with inductive load |
| Q3 | - (Generated) | - (Capacitive, Leading) | Supplies both P and Q | Renewable energy systems (PV/Wind) |
| Q4 | + (Consumed) | - (Capacitive, Leading) | Supplies Q (acts like a capacitor) | Power factor correction for inductive loads |
Fast Response Time (≤ 1 cycle) compared to SVCs (10-50 ms).
Continuous & Smooth Control (no step changes like capacitor banks).
No Harmonics (uses PWM-based inverters, no need for filters).
Bidirectional Reactive Power Flow (can switch between Q absorption and injection instantly).
Voltage & Power Factor Stabilization (improves grid stability).
Low Footprint & Modular Design (compact compared to SVCs).
IPv6 network supported
