In a diesel generator (DG) set, the major responsibility of an automatic voltage regulator (AVR) is to regulate the output voltage regardless of the load variation or other operating parameters.
Here are the key functions of an AVR in a DG set:
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Voltage Regulation
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Load Sharing in Parallel Operation
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Overload Handling
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Overvoltage Reduction
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Stable Operation
Voltage Regulation
The AVR regulates the excitation system of the generator to maintain output voltage at required setting which is constant. It, does this through constantly measuring the voltage at the generator terminal and comparing it to a reference voltage. In the case of an increase in the voltage, the AVR reduces the excitation while in the case of a decrease in the voltage the AVR increases the excitation until the voltage comes to its desired value.
Load Sharing in Parallel Operation
Load sharing in parallel operation refers to how the load is divided between the connected devices when switching between different modes.
In the case where several generators are running in parallel, the AVR plays a crucial role in determining how the reactive load is shared between the generators.
This voltage drop function makes it possible to balance the load of the generators and the load does not accumulate in one generator.
Overload Handling
The AVR helps in improving response of the generator against overload since it increases excitation under faulty conditions.
This ensures that there is adequate synchronizing power available to maintain the generator’s stability once a fault has been cleared.
Overvoltage Reduction
Further, the AVR protects the system from over voltages that may occur because of sudden load rejection. In a case that there is large load suddenly applied, the AVR promptly decrease the amount of excitation in order to maintain the voltage level to be not too high.
Stable Operation
This way the AVR enables the generator to operate nearer to its marginal stability and thus with a steady voltage level. This will enhance the operation efficiency and performance of the DG set.
AVR maintains and stabilises the voltage of the generator, controls the amount of load it takes and makes safe and efficient the operation of the DG set. Sustainable working of the AVR is very important for a generator to supply steady and clean power to the loaded appliances.
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