The excitation system controls the field current of a synchronous generator. Through this control, it regulates generator terminal voltage and reactive power while supporting stable generator and grid-connected operation.
Selecting an excitation system requires more than checking the generator’s rated output. The required system architecture also depends on excitation current and voltage, redundancy, cooling method, power cabinet configuration, communication requirements, and plant operating conditions.
NSD Electric offers three IAEC excitation system families for different generator capacities and project requirements.
IAEC-1000 for Generator Units Below 10 MW
The IAEC-1000 is a fully digital microcomputer-based excitation system designed for generator units below 10 MW.
It combines regulation, power, and de-excitation functions within one cabinet. This integrated structure reduces the number of separate cabinets required and provides a compact configuration for small hydropower and thermal power units.
The system is equipped with two industrial-grade controllers and supports IEC 61850 communication. Its modular installation structure is designed to facilitate equipment disassembly and maintenance.
For a small generating unit requiring a compact excitation package, the IAEC-1000 provides an integrated solution matched to the capacity range and typical installation conditions of smaller power plants.
IAEC-4000 for 10 MW–600 MW Units
The IAEC-4000 is designed for generator units ranging from 10 MW to 600 MW.
Unlike the integrated IAEC-1000, the IAEC-4000 uses separate regulation, power, and de-excitation cabinets. Its standardized modular structure is suitable for medium and large hydropower and thermal power plants.
The system includes a dual-channel controller, with Automatic Voltage Regulation and Manual Current Regulation available in each control arrangement. PSS-2B or PSS-4B power system stabilizers can be configured according to project requirements.
Heat-pipe cooling and forced-air cooling options are available for the power cabinets, and the system can support configurations of up to six power cabinets.
IAEC-6000 for 150 MW–1000 MW Units
The IAEC-6000 is a fiber-optic distributed intelligent excitation system designed for generator units from 150 MW to 1000 MW.
It also uses separate regulation, power, and de-excitation cabinets, but adopts a distributed architecture with fiber-optic communication. The system supports configurations of up to eight power cabinets.
Each controller channel includes Automatic Voltage Regulation and Manual Current Regulation. PSS-2B or PSS-4B power system stabilizers can also be integrated into the system.
The IAEC-6000 supports IEC 61850 communication and provides heat-pipe or forced-air cooling options. Its distributed structure is intended for large generator units that require expanded power cabinet capacity and a higher-level system architecture.
Capacity Is Only the First Selection Step
The IAEC-4000 and IAEC-6000 capacity ranges overlap between 150 MW and 600 MW. This does not mean that the two systems are interchangeable based only on generator output.
Within this overlapping range, selection should consider the required control architecture, number of power cabinets, excitation current, cooling arrangement, redundancy level, communication design, and other project-specific requirements.
Before confirming the model, the project team should provide generator parameters, rated excitation voltage and current, excitation method, required control modes, cooling conditions, protection requirements, plant communication protocols, cabinet arrangement, and available installation space.
For an existing plant modernization project, the condition and compatibility of the current excitation transformer, rectifier equipment, de-excitation equipment, field circuit, plant monitoring system, and associated wiring should also be reviewed.
A capacity-based preliminary selection can be summarized as follows:
- IAEC-1000: generator units below 10 MW
- IAEC-4000: generator units from 10 MW to 600 MW
- IAEC-6000: generator units from 150 MW to 1000 MW
The final configuration should always be determined from the generator’s actual electrical parameters and the technical requirements of the power plant.
NSD Electric provides excitation system engineering, equipment configuration, testing, commissioning, retrofit support, spare parts, and technical service for hydropower and other generating projects.
