Basler DECS-2100 Excitation System: Modular Upgrade and Engineering Application

Basler DECS-2100 Excitation System: Modular Upgrade and Engineering Application

Introduction: Evolution of Excitation Technology from Westinghouse WTA to DECS-2100

In the field of excitation control in power plants, system reliability and maintainability have always been the core concerns of engineers. Basler Electric's DECS-2100 Digital Excitation Control System represents the latest development direction in excitation technology, but its technological foundation can be traced back to the Westinghouse WTA excitation system introduced in 1962. After going through WTA-300, WTA-300B, WDR-2000, and finally ECS2200 in 2000, Basler created the DECS-2100, a powerful and highly flexible excitation platform, through continuous technological iterations.

For power generation companies operating outdated excitation systems, achieving technological upgrades without significantly increasing costs is a practical and urgent issue. The DECS-2100 and its accompanying modular upgrade solution provide a complete solution path for this requirement. This article will delve into the system architecture, core module functions, and upgrade application strategies of DECS-2100 in engineering practice.

1. DECS-2100 System Architecture and Design Concept

1.1 System Overview

DECS-2100 is a digital excitation control system that can provide up to 10000 Adc excitation current, suitable for various application scenarios ranging from small units to 1000 MVA level large generators. The system supports multiple configuration modes including single controller, dual redundant controller, or ECM-2 supervised controller, which can meet the power generation requirements of different safety levels.

The core design concept is reflected in the following four aspects:

Modularization: Each functional unit is independently packaged, making it easy to maintain and upgrade

Scalability: Supports parallel expansion of power converters, up to 14 power drawers can be connected in parallel

Redundancy capability: Supports N+1 redundancy configuration to ensure uninterrupted operation of critical tasks

Backward compatibility: All core modules support seamless replacement of ECS2200 and earlier systems

1.2 System Configuration Case

A typical application case is a 970 MVA generator set in the Midwest of the United States, which originally used a rotary excitation system and was later converted to DECS-2100 static excitation. The system is equipped with 14 parallel power drawers, which continuously output 8140 amperes of excitation current, and can maintain full load operation even when two power drawers are out of service. This renovation significantly improved system performance and reduced maintenance costs.

2. Detailed explanation of core control module: ECM-2

ECM-2 (Excitation Control Module) is the control core of the DECS-2100 system, integrating key functions such as regulation, generator set sensing, protection, and thyristor trigger control.

2.1 Technical specifications

Control power supply: dual 24 Vdc redundant input

Contact input: 4 channels, supporting ± 24 Vdc or 125 Vdc/120 Vac

Relay output: 4 channels, 7.0 A current carrying capacity

Analog input: 24 channels, 57 Vdc/40 Vac

Analog output: 2 channels, 4-20 mA or ± 10 Vdc

Fiber Channel: Bridge Control (up to 16 modules), Digital I/O (up to 2 modules), Analog I/O (up to 2 modules), Isolation Transmitters (5 modules)

2.2 Communication Interface

ECM-2 offers a wide range of communication options:

USB (1 device end, 1 host end)

Ethernet (2 independent ports)

RS-232 (1)

RS-485 Modbus (3)

IRIG-B (1 for clock synchronization)

2.3 Control Mode and Protection Function

The control modes include: automatic voltage regulation (AVR), magnetic field current regulation, magnetic field voltage regulation, reactive power (Var) regulation, power factor regulation, sag and line voltage drop compensation, and network load distribution.

Limiter coverage: Minimum Excitation Limiter (MEL), Undervoltage Limiter, Minimum Field Excitation Limiter (MFEL), Overvoltage Limiter, Underexcitation Limiter (UEL), Reactive Power Limiter, Overexcitation Limiter (OEL), V/Hz Limiter, Instantaneous Overcurrent Limiter, Generator Line Current Limiter.

Protection functions include: overvoltage/undervoltage V/Hz、 Overexcitation, demagnetization/underexcitation, sensor loss, phase imbalance, magnetic field grounding, etc.

2.4 ECM-2 Replacement Upgrade for ECS2200

ECM-2 is designed specifically to replace the "three board control group" (control board, interface board, communication board) of ECS2200. By using specialized retrofit installation boards (P/N 9469400100 and 101), upgrades can be completed with minimal wiring changes. Once the upgrade is completed, the original ECS2200 system will receive all the new features of ECM-2, including stronger processing capabilities, richer communication interfaces, and more comprehensive protection functions.

3. Detailed explanation of power and control module

3.1 BCM-2 Bridge Control Module

BCM-2 (Bridge Control Module) is responsible for monitoring and controlling a single SCR based power bridge. Each BCM-2 generates trigger pulses for six SCR bridges based on system requirements, while monitoring SCR conduction status, bridge temperature, operating power supply, and control signals.

Key improvements:

Direct USB communication

Increase the number of contact inputs from 2 to 5

All LED indicator lights are clearly labeled and can be directly observed from the power drawer cover window

The wiring position is completely consistent with the original BCM

The wide application of BCM-2: It is worth noting that BCM-2 can not only be used in DECS-2100 and ECS2200 systems, but also directly replace the IFM-105 and IFM-150 trigger circuits used in DECS-400 and DECS-450 systems. This means that the old excitation system using DECS-400/450 can also obtain modern digital triggering control capability by replacing BCM-2.

3.2 Power drawer and rectifier bridge options

DECS-2100 offers multiple standard rectifier bridge options, suitable for redundant or parallel applications:

Bridge type voltage level current level

Low voltage power drawer 600 Vac 1100 Adc

Medium voltage power drawer 900 Vac 1000 Adc

High voltage power drawer 1300 Vac 900 Adc

SSE-N rectifier bridge 320 Vac 270 Adc

Low voltage compact rectifier bridge 600 Vac 1400 Adc

Medium voltage compact rectifier bridge 900 Vac 1000 Adc

Note: The rated value of the bridge circuit needs to be reduced for use under parallel operation or specific environmental conditions.

4. Detailed explanation of I/O expansion module

4.1 AIOM-2 Analog I/O Module

AIOM-2 increases analog I/O capacity for DECS-2100 or ECS2200 systems through dedicated anti-interference fiber optic links.

Technical Specifications:

Analog input: 4 channels, ± 10 Vdc or 4-20 mA

RTD input: 2 channels, 100 Ω platinum (2 or 3 wires)

Analog output: 8 channels, ± 10 Vdc or 4-20 mA

Control power supply: 24 Vdc (redundant)

Up to 2 modules can be cascaded to achieve double capacity

Upgrade features:

Input (2 → 4), RTD (1 → 2), and output (4 → 8) are fully doubled

I/O ground isolation increased to 500 V

Compatibility mode DIP switch can seamlessly replace one or two old AIOMs

4.2 DIOM-2 Digital I/O Module

DIOM-2 provides an additional 24 contact inputs and 16 output contacts, which communicate with the controller through fiber optic links.

Technical Specifications:

Input: 24 channels, supporting 24 Vdc or 125 Vdc/120 Vac (internal switch optional)

Output: 16 channels, Form-C relay, 7.0 A current carrying

Control power supply: 24 Vdc (redundant)

Can cascade 2 modules to achieve 48 inputs/32 outputs

4.3 IT-2 Isolation Transmitter

IT-2 is used to isolate controllers from high voltage/high current signals. Typical applications include measuring rectifier bridge input voltage, magnetic field voltage, or measuring magnetic field current through a shunt.

Technical Specifications:

High voltage input: 2 channels, 2000 Vdc/1414 Vac

Split input: 2 channels, 200 mVdc/141 mVac

Range selection: DIP switch instead of jumper

The shell free version (P/N 9500800101) is suitable for old power drawers

4.4 FGD-2 magnetic field grounding detection module

FGD-2 continuously monitors the ground resistance of the synchronous motor magnetic field circuit, measures the leakage current by applying a fixed ground voltage, and provides grounding protection signals for ECM-2.

Technical Specifications:

Maximum magnetic field voltage: 800 Vdc or 1750 Vdc

Control power supply: 100/120 Vac, 50/60 Hz

Output signal: 0-15 Vdc

Upgrade features: Same installation hole spacing, same wiring position, isolated output, no need for additional configuration

4.5 DXCB-2 demagnetization/Crowbar module

DXCB-2 provides a low impedance path to discharge energy, protecting the generator's magnetic field and excitation circuit from overvoltage and arc damage. A single module can operate in either demagnetization (DX) or crowbar (CB) mode. A typical system configuration consists of two modules (one mode each) that can be connected in parallel to increase discharge current or add redundancy.

Technical Specifications:

Control power supply: 125 Vdc

External trigger: 24 or 125 Vdc

Magnetic field voltage: 600 or 1000 Vdc

Current capacity: 2000 or 5000 Adc

Upgrade features: Same installation location and wiring, voltage triggered step refinement (600 V vs 800 V), no need for external Zener diodes

5. Human computer interface and software tools

5.1 IDP-1201 Interactive Display Panel

IDP-1201 is a 12 inch color touch screen that supports excitation system monitoring and control, including system status viewing, control operations, and setpoint adjustment. The second IDP can be installed remotely (such as in the control room).

Communication interface: USB (host/device) RS-485 Modbus、 Ethernet Modbus

Compatibility: Same installation holes as the previous generation IDP-1200, no need to modify the panel for replacement, only minor adjustments need to be made to the control power wiring. In addition, an upgrade kit for the ECS2200 original PanelMate display panel is also available.

5.2 BESTCOMSPro Configuration Software

BESTCOMSPro is the main configuration tool for DECS-2100 and ECS2200 systems, which is free to use and integrates powerful testing, monitoring, and operation functions.

Core tools:

Generator simulator: Debugging and parameter tuning can be performed before the unit is started, supporting multiple unit models and load transient simulations

Self tuning tool: automatically identifies initial gain and generator time constant

Real time monitoring: monitoring up to 6 parameters simultaneously

Step/Time Response Tool: Manually Adjust Gain

Frequency response analysis: frequency scanning or white noise tool

Data recording: trend recording and event data capture

Logical View: Provides graphical Diagram View and compact Execution View for interconnecting logical blocks

BESTspace: Custom workspace layout that can be saved and reused

BESTCOMSPro is compatible with ccTools of ECS2200 and is a direct upgrade path for the latter users.

6. Upgrading and Transformation Strategies and Engineering Applications

6.1 Front End Retrofit Kit

For customers who are still using large excitation systems but whose original control parts have been phased out or are no longer supported by OEM, the DECS-2100 front-end retrofit kit is the best choice. Its core advantages lie in:

Less time: Customized panel chassis components, perfectly adapted to existing control cabinets, significantly reducing installation time

Lower risk: avoid long-term unplanned downtime caused by the original factory's cessation of support; Basler provides long-term product support and upgrade paths

Lower cost: Reuse power components with longer service life (rectifier bridge, demagnetization circuit, etc.), only update the control part

6.2 Overview of Module Level Upgrade Paths

The entire series of DECS-2100 modules are designed with the principle of "transformation friendly":

New module replaces key compatibility features of objects

ECM-2 ECS2200 three board group dedicated retrofit board with minimal wiring changes

BCM-2 ECS22100 BCM/DECS-400 IFM of the same size and wiring position

AIOM-2 ECS2200 AIOM DIP switch selects compatibility mode

DIOM-2 ECS2200 DIOM DIP switch selects compatibility mode

IT-2 ECS2200 IT has the same size and wiring, no software changes required

FGD-2 ECS2200 FGD with the same installation hole spacing (4/6 holes) and the same wiring

DXCB-2 ECS2200 DXCB with the same position and wiring, no additional configuration required

IDP-1201 IDP-1200/PanelMate with the same mounting hole position, minor wiring adjustments

6.3 Shallow Depth and Compact Solutions

For space constrained applications, the DECS-2100 offers a shallow depth solution with a depth of only 36 inches (using a compact rectifier bridge or SSE-N series rectifier bridge). The standard power drawer system has a depth of 60 inches and requires rear maintenance access.

7. Troubleshooting and maintenance recommendations

7.1 Common problem troubleshooting ideas

Communication failure: Check the fiber link connections (F1-F3 main channel, F4-F6 redundant channel) and confirm that the fiber connections between ECM-2 and each module are correct

Trigger pulse abnormality: Check the connection between the gate (G) and cathode (K) of BCM-2, and confirm that the bridge selection switch is set correctly

Analog reading deviation: Check if the V/I mode switch setting of AIOM-2 matches the actual signal type

DIOM input not recognized: Confirm if the internal switch is set to the correct voltage range (24 Vdc or 125 Vdc/120 Vac)

FGD-2 no output: Check if the Enable input is connected to a valid AC voltage and confirm if the Active Status LED is lit

DXCB-2 does not operate: Check the trigger signal voltage level (24 or 125 Vdc) and confirm that the control power supply 125 Vdc is normal

7.2 Maintenance Suggestions

Regularly check the fan operation status of the power drawer (redundant fan design)

Regularly check the LED indicator status of BCM-2 and confirm that the SCR conductivity monitoring is normal

Regularly check the range DIP switch settings of IT-2 to ensure they match the actual sensing signal

Regularly check the grounding leakage current reading of FGD-2 and promptly detect the trend of insulation degradation

Using BESTCOMSPro's Sequence of Events (SOE) and Alarm History for event tracing