GE Energy EX2100 Excitation Control User's Guide

Introduction

The EX2100 (EX2100 or exciter) produces the field excitation current to control generator ac terminal voltage and/or the reactive volt-amperes. It is a thyristor excitation system designed for generators on both new and retrofit steam, gas, and hydro turbines.

This chapter introduces the exciter and defines the document contents. Its purpose is to present a general product overview as follows.

System Overview

The exciter is a flexible modular system that can be assembled to provide a range of available output currents and several levels of system redundancy. These options include power from a potential, compound, or auxiliary source. Single or multiple bridges, warm backup bridges, and simplex or redundant controls are available. An overview of the turbine generator excitation system is shown in the figure Overview of Generator and Exciter System.

Power for the exciter is drawn from a power potential transformer connected to the generator terminals, or from an excitation transformer connected to an auxiliary bus. Generator line current and stator output voltage are the primary feedbacks to the exciter, and dc voltage and current is the controlled output to the exciter field.

The EX2100 supports both static excitaion systems and rotating exciters such as brushless and Alterrex

The architecture supports Ethernet LAN (Unit Data Highway) communication with other GE equipment including the GE Control System Toolbox (toolbox) for configuration, the turbine control, the LS2100 Static Starter, and the HMI (operator interface).

The Exciter One Line Diagram is a simplified one line diagram of the exciter showing the power source, generator current and voltage measurements, control module, power conversion module (PCM), and protection circuits. In the potential source system, the secondary of the PPT is connected to the input of a 3-phase full wave inverting thyristor bridge. The inverting bridge provides both positive and negative forcing voltage for optimum performance. Negative forcing provides fast response for load rejection and de excitation.  

Excitation control results from phase controlling the output of the SCR bridge circuit. The SCR firing signals are generated by digital regulators in the controller. In the redundant control option (See Exciter One Line Diagram), either M1 or M2 can be the active master control, while C monitors both to determine which should be active and which should be standby controller. Dual independent firing circuits and automatic tracking are used to ensure a smooth transfer to the standby controller.

Hardware Overview

The EX2100 hardware is contained in cabinets as follows: 

 • Control cabinet for the control, communication, and I/O modules 

 • Auxiliary cabinet for field flashing and protection circuits such as de-excitation and shaft voltage suppression   

• Power conversion cabinet for the power SCR cells, cooling fans, dc contactors, and ac disconnect

The exciter's power converter consists of bridge rectifiers, resistor/capacitor filter configurations, and control circuitry. An outside view of the cabinets for a typical 77 mm or 53 mm warm backup lineup is shown in the figure Exciter Cabinets (77 mm and 53 mm WBU Typical). The components and bridge size vary for different excitation systems and for the power output required.

Bridge sizes are referenced to the size of the SCR device used. 100 mm, 77mm, 53 mm, and 42 mm (equivalent) sizes are available. Bridge configurations of simplex or single bridge, warm backup or redundant bridge, multiple parallel bridges (up to 4 total), and N+1 or N+2 online maintainable versions are available. The 42 mm thyristor bridge is available in both inverting and non-inverting topologies. The larger bridge sizes are always supplied as inverting bridges.

The EX2100 is also available without a power converter, as a Digital Front End Control only, for bridge retrofit applications. The 42 mm power modules are available as separate modules to facilitate upgrades into existing power converter cabinets, such as Frame 5 generator control installations.

Software Overview

Microprocessor-based controllers (ACLx and DSPX) run the exciter control code. The software consists of modules (blocks) combined to create the required system functionality. Block definitions and configuration parameters are stored in flash memory, while variables are stored in random-access memory (RAM).

The exciter application software emulates traditional analog controls. It uses an open architecture system, with a library of existing software blocks configured from the toolbox. The blocks individually perform specific functions, such as logic gates, proportional integral (P.I.) regulators, function generators, and signal level detectors. The control selects one of two modes, either generator voltage regulation (Auto Regulation), or direct control (voltage or current, depending upon the application). Generator protection functions are integrated into the control, including over and under-excitation limiting, power system stabilization, and V/Hz limiting.

The blocks can be interrogated while the exciter is running by using the toolbox. The dynamically changing I/O values of each block can be observed in operation, which is valuable during startup or troubleshooting.

GE EX2100 Static Excitation System complete core model list

System ownership: GE EX2100 (supporting Mark VI/Mark VIe turbine control platform, upgraded version called EX2100e)

It is divided into three categories: control rack board, power module and terminal/interface board.

First, the three models you mentioned.

1. cm03: ex2100 excitation control module (excitation master control module)

2. 151x1207ck02sa02: SCR power module+turbo vacuum contactor, 4400V,1850A.

3. is200 ed ex g1ada: edex de-excitation control board.

Second, the control core board (IS200 series)

-is200dspxh1a/is200dspxh1b: dspx main processor board (controller core)

-is200emi oh1a: emio exciter main I/O board excites the main I/o board.

-is200esellh1a/is200eselh1aaa: ESEL exciter selector board excitation gating board, SCR pulse distribution.

-IS200EGDMH1A：EGDM excitation grounding detection board and rotor grounding protection.

-is200examg1a: ExamExciter Attenuator Module attenuator board, complete with grounding detection.

-is200eh pag1d/is200eh pag2d: HV gate pulse amplifier high voltage pulse amplifier.

-is200epsmg2a: power board of epsm power supply module rack.

-is200erscg1a: ERSC static converter board static converter board

-is200b ICL h1 aed: bridge interface card bridge interface board

-is200da MB g1acb/is200dameg1adb: gate driver card gate driver board.

Third, the feedback and terminal board

-IS200EPCTG1A：PT/CT/CT voltage and current acquisition board

-is200ebk pg 1c: ex2100 Backplane

-IS200ECTBG1A/IS200ECTBG2A: excitation contact terminal board (TMR/Simplex)

-IS200EDCFG1B：DC Feedback Board DC feedback board

-IS200EACFG3B：AC Feedback Board AC feedback board

Fourth, power hardware components (151X high-power series)

-151x1207ck02sa02: SCR assembly with vacuum contactor (yours)

-151X1202YE11SA02: Excitation power bridge assembly

-151X1207CK series: several variant models of SCR vacuum contactors with different current levels.

V. System Version

-EX2100: classic old model, adapted to Mark VI.

-EX2100e: upgraded version, adapted to Mark VIe, ControlST software.