GE EX2100e Excitation System Complete Guide

Control software and core functional modules

The control software of EX2100e is controlled through ToolboxST ™ Perform configuration, loading, and debugging. The software uses Function Block Diagram (FBD) to display signal flow, and all control, restriction, and protection functions are presented in modular form.

3.1 Signal acquisition and preprocessing

The voltage and current signals of the PT/CT at the generator end are connected to the ESYS (EX2100e system interface board), which completes signal isolation, filtering, and scaling. The controller synchronously samples the AC waveform at high speed and calculates the following key variables through mathematical algorithms:

Terminal voltage, active current, reactive current

Frequency and slip (reflecting changes in rotor speed)

Power, reactive power V/Hz、 Power factor, magnetic flux amplitude

3.2 Automatic Voltage Regulator (AVR) and Manual Regulator

AVR: Maintain a constant voltage at the generator terminal during normal operation, responding to changes in load and operating conditions.

Manual regulator (FVR/FCR): When PT is disconnected or AVR fails, the manual regulator directly controls the excitation voltage or current. The GE standard uses FVR (Field Voltage Regulator) instead of FCR (Field Current Regulator) because FCR weakens the signal independence of the over excitation limiter.

Tracking mechanism: The inactive regulator automatically tracks the output of the active regulator through a software ramp function, ensuring no disturbance during switching.

3.3 Key limiters and protection functions

Function Name Function Description

Over excitation limiter (OEL) prevents long-term overcurrent of magnetic field, complies with ANSI C50.13 standard, and adopts inverse time limit curve

Underexcitation limiter (UEL) limits the demand of AVR for underexcited reactive current, avoiding exceeding the static stability limit or overheating of the stator core end

When the stator current exceeds the rated value, the AVR automatically switches to the preset reactive power control mode

V/Hz limiter and protection limit V/Hz ratio (typical value ± 5% rated), exceeding 1.10 p.u. inverse time limit alarm, 1.18 p.u. delayed tripping for 2 seconds

PT disconnection detection (PTFD) detects feedback voltage loss, issues an alarm, and switches to manual regulator (if a disconnection is detected and there is no single-phase fault, the system first forces the output to the top value for 0.5 seconds before switching)

Generator overvoltage trip (59G) monitoring terminal voltage, triggering trip when exceeding the set value

Demagnetization protection (40) based on impedance and reactance two zone timed tripping

Engineering application scenario: When the hydrogen pressure of a hydrogen cooled generator changes, the hydrogen pressure/temperature compensation function will automatically adjust the parameters of UEL, OEL, and stator current limiter to avoid misoperation.

3.4 Power System Stabilizer (PSS)

The PSS of EX2100e adopts a multi input scheme, which comprehensively utilizes the active power and internal frequency (approximate rotor speed) of the synchronous motor to generate a signal proportional to the rotor speed. This signal is obtained by integrating the acceleration power and effectively attenuating the shaft torsional vibration signal, thereby improving the dynamic stability of the power system.

3.5 Reactive Power Compensation and Line Drop (RCC/Line Drop)

RCC mode: Achieving balanced distribution of reactive current between parallel connected groups

Line Drop mode: provides better voltage regulation for a certain point downstream of the generator bus

3.6 Generator Simulator (GEN SIM)

As a detailed generator model built into the software, GEN SIM can be configured to match the actual generator characteristics. During the shutdown of the unit, it can be used for operator training, testing of regulator and limiter functions, and verification of protection logic.

3.7 Communication and Integration

Unit Data Highway (UDH): Based on the EGD protocol, it connects the excitation system with the turbine control system HMI、 Data center, supporting ToolboxST configuration and maintenance

DCS interface: Supports Modbus RTU/TCP over Ethernet 10/100baseT, can receive lifting commands and data

Integration with Mark VIe: When the excitation system is coordinated with the GE Mark VIe turbine control system, VAR/PF control is typically implemented on the turbine side

Engineering Practice: Debugging, Testing, and Troubleshooting Approach

4.1 Factory testing and on-site witnessing

Each EX2100e undergoes routine testing before leaving the factory:

Circuit continuity check

Dielectric (withstand voltage) test (compliant with IEEE 421 standard)

All component functionality verification

Customers can choose:

Option A (free): Check appearance and craftsmanship, review engineering and testing documents

Option B (chargeable): Witness hardware and software demonstrations on-site

Suggestion: For critical units, it is recommended to choose option B, familiarize yourself with the operating interface in advance, and verify the customized logic.

4.2 Common on-site problems and solutions