GE DS200TCCBG1B (DS200TCCBG1BED) Microprocessor Application Board

The DS200TCCBG1B (TCCB) is a core microprocessor application board designed by General Electric Company (GE) for the EX2000 series of digital excitation systems. As a vital component of the EX2000 exciter controller, the TCCB board undertakes critical signal processing, instrumentation generation, and system simulation functions. Positioned at the front-end processing stage of the excitation control system, it is responsible for acquiring, isolating, conditioning, and converting various analog sensing signals from the generator and exciter system. Through its built-in high-precision software transducers, these signals are transformed into standardized digital data for advanced control, regulation, and protection logic computations by the system's main processor (e.g., DS200SDCC).

The EX2000 Digital Exciter is an advanced, microprocessor-based static excitation system primarily used for controlling the field current of synchronous generators. Its purpose is to maintain stable generator terminal voltage, regulate reactive power, and ensure the safe and stable operation of the unit within the power grid. The DS200TCCBG1B serves as the system's "sensory and computational core" and "built-in test engine." Its performance is directly linked to the measurement accuracy, control quality, and maintainability of the entire excitation system.

2. Core Functions and Features

The design of the DS200TCCBG1B board integrates high-performance signal processing with flexible software configurability. Its main functions and features are as follows:

1. High-Precision Multi-Channel Signal Processing:

• The core function of the TCCB board is to process generator electrical signals from the "Potential Transformer Current Transformer Board (DS200PTCT)." This includes up to six generator voltage (PT) signals and three generator current (CT) signals.

• On-board circuits provide high-precision isolation, scaling, and conditioning for these low-level AC signals, preparing them for subsequent analog-to-digital conversion, ensuring data accuracy and noise immunity.

2. Built-in Software Transducers:

• Three-phase voltage and current RMS values (Vrms, Irms)

• Active power (MW), Reactive power (MVAR)

• Power Factor (PF)

• Frequency (Hz)

• Sequence components of voltage and current (for unbalance detection)

• This is a key technological highlight of the TCCB board. Traditional hardware transducers are replaced by efficient software algorithms. The conditioned analog signals are converted to frequency signals via Voltage Controlled Oscillators (VCOs) and then sampled by the microprocessor.

• Configurable software algorithms directly calculate crucial generator operating parameters, such as:

• Software transducers eliminate hardware drift, improve long-term stability, and offer great flexibility as ratio changes can be made via software adjustments.

3. Built-in Generator and Excitation System Simulator:

• The TCCB board incorporates a powerful software simulation model for emulating generator set and exciter system operation both offline and online.

• Offline Application: When the generator is offline or shut down, maintenance personnel can use the simulator to test all regulatory, limiting, and protective functions of the exciter controller. This verifies software configuration and parameter tuning and facilitates personnel training without needing to start the actual generator, enhancing safety and efficiency.

• Online Application: Can assist in fault diagnosis and performance analysis during system operation.

• The simulator can model different generator types (e.g., static exciter), system frequencies (50/60 Hz), feeding methods (terminal-fed/separately-fed), etc., adapting to various application scenarios.

4. Auxiliary Analog/Current Loop Inputs and Outputs:

• In addition to standard PT/CT inputs, the TCCB board (via the PTCT board interface) provides multiple general-purpose analog input channels. These can accept ±10V DC voltage signals or 4-20mA current loop signals for connecting external auxiliary signals like hydrogen pressure, winding temperature, or power factor setpoints.

• It also provides isolated and non-isolated analog output channels (e.g., 4-20mA) for outputting calculated variables or driving external meters.

5. Seamless Integration with Main Controller:

• The TCCB board connects to the system's main Drive Control Card (DS200SDCC) via a high-speed bus (e.g., JKK connector), delivering processed digital signals and calculated variables in real-time to the main processor.

• This distributed processing architecture offloads computational burden from the main processor, allowing it to focus on core control algorithms and logic decisions, enhancing overall system response speed and reliability.

6. Configurable Software-Based Design:

• On-board functions, especially the simulator model and some signal processing parameters, are configurable and adjustable using GE's proprietary "Control System Toolbox (CST)" software.

• Related configuration parameters are stored in EEPROM, allowing users to customize settings based on specific generator parameters and field applications, achieving a high degree of engineering adaptability.

3. Application Scenarios and Advantages

Application Scenarios:
The DS200TCCBG1B board is specifically designed for medium to large synchronous generator sets utilizing the GE EX2000 digital excitation system. It is widely used in:

• Thermal Power Plants: Excitation control for coal-fired and gas turbine steam generator sets.

• Hydroelectric Power Stations: Excitation control for hydro-generator sets.

• Nuclear Power Plants: Excitation systems for standby or auxiliary generators.

• Industrial Drives & Marine Power: Excitation management for large industrial synchronous motors or shipboard power stations.

• Any application requiring high-performance, high-reliability excitation control for synchronous generators.

Product Advantages:

1. High Measurement Accuracy and Stability: The use of software transducer technology eliminates aging and temperature drift inherent in analog hardware, providing long-term stable and precise electrical measurements. This forms the foundation for high-quality voltage regulation and protection.

2. Powerful Diagnostic and Testing Capability: The built-in simulator is an excellent engineering and maintenance tool. It allows for comprehensive closed-loop testing of the entire excitation control system, including all AVR, FCR, UEL, OEL, and other regulation and protection functions while the unit is offline. This significantly reduces commissioning time and improves maintenance efficiency and safety.

3. High System Integration and Reliability: As a dedicated processing unit for the EX2000 system, it is deeply integrated with hardware like the PTCT board and SDCC main control board. This optimizes system architecture, reduces external wiring and intermediate links, and enhances overall noise immunity and reliability.

4. Flexible Configuration and Adaptability: Software-configurable parameters (EEPROM variables) cover signal scaling, simulation modes, function enabling, and more. This allows the same hardware platform to flexibly adapt to generator sets of different capacities and parameters, reducing hardware variety and lowering spare parts inventory costs.

5. Enhanced System Maintainability: The rich set of calculated variables (e.g., VAR.1010 Field Temperature, VAR.1152/1153 Active/Reactive Power) can be monitored in real-time via the Toolbox or Programmer, providing transparent data for fault analysis and performance optimization. Clear signal flow and modular design also facilitate fault localization.

4. Usage and Maintenance Key Points

1. Electrostatic Discharge (ESD) Protection: The DS200TCCBG1B board contains ESD-sensitive components like MOSFETs. Always wear an anti-static wrist strap and handle the board on an anti-static mat when handling, installing, or replacing it.

2. Power-Off Procedure: Before inserting, removing, or measuring any board within the exciter controller, ensure all system power sources (AC control power, DC battery power) are completely disconnected and safely isolated.

3. Configuration Management: When replacing a TCCB board, it is often necessary to restore its specific configuration data from the old board or a backup (typically by downloading a complete configuration file via the Control System Toolbox). Also, verify that the settings on the connected PTCT board are compatible.

4. Software Tools: In-depth configuration, parameter adjustment, or utilization of the simulator function of the TCCB board requires the use of GE-authorized "Control System Toolbox (CST)" software. Basic monitoring and diagnostics can also be performed using the EX2000's built-in "Programmer Module."

5. Troubleshooting: When the excitation system exhibits faults related to measurement (e.g., inaccurate voltage display, incorrect power calculation, simulator malfunction), after checking the primary PT/CT circuits and the PTCT board, focus should be directed to the TCCB board and its connections (e.g., JKK cable) using fault codes (see manual Chapter 8) and variable monitoring in the Toolbox.

6. Documentation Adherence: Before performing any commissioning or maintenance work, carefully read and understand the GEH-6121 manual (especially Chapter 4: Software Configuration and Scaling, Chapter 6: Regulator Adjustments and Testing) and the specific document for the TCCB, GEI-100163.