AVR

Principle of Generation Voltage Control:

Generation voltage control, also known as voltage regulation, is crucial in power generation systems to maintain a stable and consistent voltage output. The principle involves adjusting the excitation of the generator to regulate the terminal voltage. The generator’s excitation is controlled by varying the DC current supplied to the rotor’s magnetic field.

Objective:

The primary objective of generation voltage control is to maintain a constant terminal voltage, despite changes in:

1. Load current
2. Power factor
3. Speed
4. Temperature

HeadingAutomatic Voltage Regulator (AVR):

An Automatic Voltage Regulator (AVR) is a feedback control system that automatically adjusts the generator’s excitation to maintain a constant terminal voltage. The AVR’s primary function is to regulate the voltage output by controlling the exciter’s output.

Functioning of an Automatic Voltage Regulator:

HeadingThe AVR consists of the following components:

1. Voltage Sensor: Measures the generator’s terminal voltage.
2. Error Detector: Compares the measured voltage with a set reference voltage.
3. Amplifier: Amplifies the error signal.
4. Exciter: Supplies DC current to the rotor’s magnetic field.
5. Feedback Loop: Continuously monitors the terminal voltage and adjusts the exciter output.

Operation:

1. The voltage sensor measures the generator’s terminal voltage.
2. The error detector compares the measured voltage with the set reference voltage.
3. If the measured voltage deviates from the reference voltage, an error signal is generated.
4. The amplifier increases the error signal’s magnitude.
5. The amplified error signal controls the exciter’s output.
6. The exciter adjusts the DC current supplied to the rotor’s magnetic field.
7. The generator’s magnetic field strength changes, affecting the terminal voltage.
8. The voltage sensor measures the new terminal voltage.
9. The error detector compares the new voltage with the reference voltage.
10. Steps 3-9 repeat continuously, maintaining a stable terminal voltage.

Types of AVRs:

1. Electronic AVRs (using transistors or ICs)
2. Magnetic AVRs (using magnetic amplifiers)
3. Static AVRs (using power electronic devices)

Benefits:

1. Maintains stable voltage output
2. Improves power quality
3. Enhances generator efficiency
4. Reduces wear and tear on equipment
5. Prevents voltage-related damage

In summary, the Automatic Voltage Regulator plays a vital role in maintaining a stable and consistent voltage output in power generation systems by continuously adjusting the generator’s excitation in response to changes in load, power factor, speed, and temperature.