In diesel generator sets, PMG (Permanent Magnet Generator) and AREP (Auxiliary Winding Excitation System) are two important excitation systems that provide stable power to the AVR (Automatic Voltage Regulator). These systems are particularly effective in maintaining voltage stability under conditions of large load variations or complex operational requirements. Here’s an overview of the main functions of PMG and AREP systems:

PMG (Permanent Magnet Generator System)

The PMG system uses rotating permanent magnets to generate power independently of the main generator unit, supplying stable power to the AVR. Its main functions include:

● Providing Stable Power: Since the PMG system operates independently of the main generator’s output voltage, it can continue to provide stable power to the AVR even when the generator load fluctuates.

● Quick Voltage Response: The independent power source from the PMG enables the AVR to quickly adjust voltage, especially useful in cases of sudden load changes or non-linear loads, helping to restore the voltage to the preset level rapidly.

● Upgradable and Easy Maintenance: As the PMG system is located outside the main generator unit, it can be added as an upgrade, and maintenance is generally straightforward. Many high-power diesel generator sets include PMG systems as standard equipment.

AREP (Auxiliary Winding Excitation System)

The AREP system uses two independent auxiliary windings to supply higher current support to the AVR, with main functions including:

● Enhanced Transient Current Supply: The first winding in the AREP system operates similarly to a SHUNT system, while the second winding provides additional current to support the AVR in handling up to 300% load for a short period (usually 10 seconds). This capability helps maintain voltage stability even during high-demand operations like load start-ups or parallel operation.

● Adaptation to High-Demand Loads: The AREP system is ideal for heavy and non-linear loads sensitive to voltage fluctuations, effectively reducing voltage deviations and ensuring stable generator operation under heavy or sudden load conditions.

● Integrated Design Requires Disassembly for Maintenance: Since the AREP system is integrated within the generator, maintenance typically requires disassembly of the generator, making repairs relatively more complex.

In diesel generator sets, both PMG and AREP systems significantly enhance the generator’s voltage regulation performance. The PMG system provides an independent and stable power source for quick response to load changes, while the AREP system supplies additional current support, making it particularly suited for heavy and fluctuating load scenarios to ensure voltage stability and power quality.