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Synchronous Condenser Theory

A synchronous condenser is a synchronous machine that operates at synchronous speed without a mechanical load, providing reactive power compensation by varying its field excitation. It can absorb or supply reactive power depending on its excitation state, making it useful for voltage support and stabilizing power factors in various applications. While it offers continuous control and high reliability, it comes with higher initial costs and maintenance needs.

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26 views3 pages

Synchronous Condenser Theory

A synchronous condenser is a synchronous machine that operates at synchronous speed without a mechanical load, providing reactive power compensation by varying its field excitation. It can absorb or supply reactive power depending on its excitation state, making it useful for voltage support and stabilizing power factors in various applications. While it offers continuous control and high reliability, it comes with higher initial costs and maintenance needs.

Uploaded by

vmudiraj355
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Synchronous Condenser

Background Theory

Power Factor & Reactive Power:

In AC systems, power is divided into:

- Active Power (P): Actually consumed (in kW)

- Reactive Power (Q): Maintains electric/magnetic fields (in kVAR)

- Apparent Power (S): Combination of P and Q (in kVA)

Power Factor (PF) = P / S

Low PF implies more reactive power, which increases system losses and voltage drops.

Need for Reactive Power Compensation:

Long transmission lines and heavy inductive loads (e.g., motors) can lead to lagging power factor.

To reduce transmission losses, maintain voltage, and free up capacity, we compensate reactive power using

capacitors, static VAR compensators, or synchronous condensers.

What is a Synchronous Condenser?

A synchronous condenser is a synchronous machine that:

- Runs at synchronous speed

- Is not connected to a mechanical load

- Its field excitation can be varied, allowing control over reactive power output

Operating Principle:

- Under-excited: Absorbs reactive power (acts like an inductor)

- Over-excited: Supplies reactive power (acts like a capacitor)


Synchronous Condenser
Relevant Plots and Diagrams

Phasor Diagram:

Q-axis is reactive power, P-axis is active power.

- Over-excited: supplies VARs

- Under-excited: absorbs VARs

V-Curve:

Shows armature current (Ia) vs. field excitation (If)

- Minimum armature current at unity power factor

- Left: Under-excited (lagging)

- Right: Over-excited (leading)

Capability Curve:

Operating limits of a synchronous condenser.

- Upper half: Over-excited (positive Q)

- Lower half: Under-excited (negative Q)

Applications

- Voltage support in transmission systems

- Stabilizing power factor in industrial plants

- Dynamic reactive power compensation in grids

- Support for renewable energy integration

Advantages

- Continuous and smooth control of reactive power


Synchronous Condenser
- High short-circuit contribution

- Long life and proven technology

Disadvantages

- Higher initial cost and maintenance

- Mechanical losses and need for auxiliary systems

Summary Table

| Feature | Description |

|------------------|--------------------------------------------|

| Machine Type | Synchronous motor without load |

| Main Function | Reactive power compensation |

| Control Method | Varying field excitation |

| Operation Mode | Under/over-excited for lagging/leading VARs|

| Key Plot | V-Curve, Phasor Diagram, Capability Curve |

| Applications | Voltage control, power factor correction |

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