GE 151X1215GD01SA21 Gate Driver Board

GE  151X1215GD01SA21   Gate Driver Board

the generator field current as the feedback input. While it does regulate constant field

current over varying field temperature, GE has not selected the FCR as its standard

manual regulator because it inhibits the signal independence from the over excitation

limiter.

Manual Regulator Reference (MANUAL REF) generates the manual setpoint

variable for the manual voltage regulator (MVR). Operator commands, (raise and lower

inputs) come in from direct inputs or over a data link from an HMI operator station or

from a plant DCS or remote dispatch system.

Manual Restrictive Limiter limits the under-excited operation of the EX2100e

while the manual regulator is selected (FVR or FCR). It also does not allow the manual

regulator to track the automatic regulator when the unit is operating below the field

voltage limit called for by the manual restrictive limiter.

Overexcitation Limiter (OEL) and Offline Overexcitation Protection

(OLOT) protect the generator field from damage by events that require abnormally high

field currents. These high currents, over an extended time, can overheat the field and

cause damage. Generator fields are designed to ANSI standard C50.13. which specifies

the overvoltage as a function of time that the field is designed to follow. This standard

uses curves to describe the field overheating as a function of time and current.

Potential Transformer Fuse Failure Detection (PTFD) detects loss of PT

feedback voltage to the voltage regulator. If the sensing voltage is lost or if it is

single-phased, there is a transfer to the manual regulator and an alarm output is provided.

Power System Stabilizer (PSS) provides an additional input to the automatic

regulator to improve power system dynamic performance. The PSS offered in the

EX2100e control is a multi-input system using a combination of synchronous machine

electrical power and internal frequency (which approximates rotor speed) to arrive at a

signal proportional to rotor speed. This comes from the integral of accelerating power, but

with shaft torsional signals greatly attenuated.

Reactive Current Compensation (RCC/Line Drop) has two modes: RCC and

Line Drop. The RCC mode permits sharing reactive current between paralleled machines.

Line Drop mode allows for better regulation of voltage at some point down stream from

the generator terminals.

Stator Current Limit (SCL) determines the AVR/VAR control. When the generator

stator current exceeds the rated value, the exciter changes from AVR control to a VAR

control preset. Once the stator current is less than the rated value, the exciter returns to

AVRcontrol