How AVR helps to control or operate OLTC for achieving smooth variations voltages?

How AVR helps to control or operate OLTC for achieving smooth variations voltages?

An Automatic Voltage Regulator (AVR) helps control the On-Load Tap Changer (OLTC) of a power transformer to achieve smooth voltage variations. 

Automatic Voltage Regulator (AVR)

The AVR is an electronic device designed to maintain a constant voltage level in power systems. It detects changes in the output voltage and adjusts the input voltage to maintain a stable output.

On-Load Tap Changer (OLTC)

The OLTC is a mechanism in a transformer that allows the adjustment of the transformer’s voltage ratio under load conditions without interrupting the power supply. It works by changing the transformer’s tap position, which effectively adjusts the number of turns in the winding and hence the output voltage.

Interaction between AVR and OLTC

1. Voltage Sensing:

 - The AVR continuously monitors the output voltage of the transformer. If the voltage deviates from the preset desired level, the AVR detects this deviation.

2. Control Signal Generation:

 - When a voltage deviation is detected, the AVR generates a control signal. This signal is proportional to the magnitude and direction of the voltage deviation.

3. OLTC Operation:

 - The control signal is sent to the OLTC mechanism. The OLTC then operates to change the tap position. For instance, if the voltage is too low, the OLTC will change to a higher tap to increase the voltage, and vice versa.

4. Feedback Loop:

 - After the tap change, the AVR again measures the output voltage to check if it has reached the desired level. This creates a feedback loop, ensuring continuous and dynamic adjustment to maintain the set voltage level.

Smooth Voltage Variation

- Gradual Adjustment:

 - The AVR ensures that the tap changes are gradual, avoiding abrupt voltage variations that could cause instability or damage to connected equipment.

- Dead band Setting:

 - The AVR can be set with a dead band, a small range around the desired voltage level where no tap changes occur. This prevents unnecessary tap changes for minor voltage fluctuations, thus providing smoother voltage control.

- Time Delay:

 - A time delay feature can be included in the AVR to prevent frequent tap changes caused by transient conditions. This delay allows the system to ignore short-term fluctuations and only react to sustained voltage changes.

Benefits

- Enhanced Stability:

 - The combination of AVR and OLTC helps maintain voltage stability across the power system, ensuring a reliable supply to consumers.