pdvsa igv control

8/13/2019 Pdvsa Igv Control

http://slidepdf.com/reader/full/pdvsa-igv-control 1/17

Caterpillar Confidential - Yellow

G.A.Hansen

MOOG-ACT IGV

CONTROL-PDVSA



General Questions to All Manufacturers


2

Safety

Perform the necessary task assessments

prior to starting the job based on the site

condition in order to perform your task in a

safe manor.

Save (upload) the original as installed

software prior to performing any changes or

calibration.

Remember to always compare your finalwork for AFI’s etc.





3

Setup-Calibration

Implemented the control changes to allow for active guide vane control, in turn up rating a

current Mars 90 to a Mars 100 configuration. This initialed modifying the current control

Moog Servo System typically utilized for surge avoidance 80%-92% Ngp_Corr to an active

control varying the position through the operating range > 92% Ngp_Corr based on full

load.

Setup-Calibration

The calibration of the control needs to be performed in two steps.

1. The first being a static verification of both the on skid components and software constants.

2.Operational trimming of the full load position based on overall performance parameters.

To perform this function a copy of the test report is required

This outline is not going to get into specific calculations utilized to determine the number of

bits for a specific position due to the scaling conversion etc for the Moog control. However

this will serve as a straightforward means to properly setup and determine thefunctionality of the control. Service Bulletin 8.6/106B should be used as a reference only for

this control setup





4

INITIAL CONSTANTS IGV

Initial Constants Settings –Typical Moog Actuator

RED – indicates a fixed constant, Blue – indicates variable constant. F13:551, GVAG_CLIM = -45 Minimum limit closed position

F13:548, GVAG_OFST = 0 IGV angle offset (bias to normal schedule)

F13:552, GVAG_INTM = -4 IGV intermediate set point

F13:553, GVAG_FULOP = 2.5 Deg full open limit

F13:555, GVDRIZCNT = -3662.00 Approximate zero count

F13:559, GVAG_INTH = 0.8 (needs to be set at –

2.0 during initial setup) F13:162, GVPSTNIPGN = 1.2 Utilized to trim the control linearity (position verses feedback) (0.5-

1.5) Feedback gain.

F13:163, GVPSIPOFST = 0 for this application the setting will be 0

F13:165, GVOVDSLPE = 1.67 Ngp IGV over ride gain

F13:166, GVCLOSELMT = 3.6 Representative VDC closed limit

F13:167, GVOPENLMT = -3.6 Representative VDC open limit

F13:168, GVDRIVGAIN = 0.5 Utilized for control stability (0.3-1.0)

F13:169, GVDRIVOFST = .10 Offsets the output control to the actuator





5

Standard Match Temp IGV

Verify that Ngp_Corr is being

calculated correctly in file 89 and

make sure 59º is utilized in the

standard temp calculation (not 80

or 122 etc). Standard day temp is

defined to be 59 deg at sea level.

Remember that Engine Match is a

function of the nozzle shape notambient temp.

A consequence of changing the

IGV setting is a different airflow,

different T3, and different pressure

ratio.





7

Signal Conditioner-Actuator Cal

Step-1

o The control is a closed loop system, +10 volt output signal address (N??) through a

voltage/current converter (Z230) –50/50mA to the servo-controller (pilot valve) located just

under the forward engine support. The control feed back is an iatrical part of the singleMoog actuator containing the (LVDT) Liner Variable Differential Transformer through a

signal conditioner (Z339) +3.6 FB signal through input address (N??)

o At this point verification of the Signal Conditioner (Z339) and mechanical position of the

Moog Actuator relative to the voltage FB signal needs to be performed. This task needs to

be performed at the unit and there are several ways to accomplish this including the

procedure listed within SB8-6-106B.

o 1. Follow the procedure listed in SB8-6-106B, however tedious.

o 2. Move the guide vanes manually, which will require the actuator lube lines be removed. Make sure

both the AC and DC lube pumps are isolated (tagged out) and the engine has completed the 4hr

post lube.

o 3. Within the logic set both the min closed –45º and 0º FB-position through the logic.

o a. The engine will need to be placed in the TEST CRANK mode in order to build hydraulic pressure.o b. Very the guide vanes between – 45 and 0 by entering a bit count within the output address N??

(typically 215 bits corresponds to – 45 and –3660 bits corresponds to 0) on the Mars engine

degree angle plat located at the engine. Verify that the corresponding feed back signal on

terminals 7 & 8 of the signal conditioner are within limits (- 45 = 3.6VDC and 0 = -3.6VDC)





8

Signal Conditioner-Actuator Cal

Step-1

Signal Conditioner

OFFSET-ZERO

OUTPUT-SPAN

7 8

1. Move the IGV arm to – 22.5°,

adjust the OFFSET- ZERO.

2. Move the IGV arm between

– 45° (+3.6) min and 0° (-3.6),

adjust the OUTPUT-SPAN

+5

-5

0V

Deg-Angle

– 22.5°

Zero Offset

Output Span

-3.6

+3.6

On Eng Adjustment

Max Actuator

Exstention

– 45° 0

Servo Controller InPt Cont Sig

FB Sig

LVDT

E i C k V ifi i





9

Engine Crank Verification

Step-2

The next step in the IGV control

verification will be performed during an

engine crank cycle, it’s best to have the

engine oil as close to operating

temperature as possible however not

imperative

.

1. Go on line with field programming terminal

to file 145 and set the Ngp_Corr to 80%

2. With the engine Ready Light illuminated

perform a test crank.

3. Drive the IGV’s fully open and closed

utilizing the GVOPENLMT (-4.4 or –3.6 =

OPEN) (+3.6 = Closed).

4. Utilize SB8.6/106B section 2.15-2.15.4 in

order to establish a new position gain.

Whatever number is placed in the

GVOPENLMT will drive the IVG’s. Record

the following feedback signal within the

program 145:9

a. Fully open voltage (?) -4.4 to drive open

b. Fully closed voltage (?) +3.6 to drive closed

c. Position –40, V-40 (?) Increase till –40

d. Position –5, V-5 (?) Increase till -5





10

Guide Vane Pos Gain Corr

Step 2

Place the initial calculated GVPSTNIPGN from index (4) into F13:162





11

Logic AFI Ngp_Corr

Move back to file 145 and

locate rung 145:10 or the

rung that drives the full

open position during a

crank and place an AFIinstruction. This rung

moves the IGV to the full

open position during an

test crank.





12

Engine IGV Tracking Verification

Step 2

• Set F13:548 (GVAG_OFFST)= 0, CRANK and

adjust the Ngp_Corr per the listed scale and

note both the calculated schedule (GVAG_SCH)

and feedback (GV_DEG) along with verifying

the angle scale located on the engine. Adjust

Kval (F13:162, GVPSTNIPGN) again if needed in

order to trim the feedback and bring it in line

with the actual position.

• During the process of verifying both the controland feedback signals it’s important to make

sure the actual guide vane position is stable at

the engine. If the IGV’s are fluctuating for a

specific output adjust F13:168, GVDRIVGAIN

(.4-.6 seems to work well) however is site

specific and may need to be readjusted once

the engine is operational depending on the lube

oil temperature during the testing phase.

F13:169, GVDRIVOFST can be left at (.10), this

will effect the position relative to the output

signal.

IGV ANGLE

-45 -45 -37.5 -30 -22.5 -15 -7.5 00

80 82 84 86 88 90 92

-100

-50

0

50

100

Angle

N g p

_ C o r r

Angle

Ngp_Corr

Angle -45 -45 -37.5 -30 -22.5 -15 -7.5 0

Ngp_Corr 0 80 82 84 86 88 90 92

1 2 3 4 5 6 7 8





13

Engine IGV Tracking Verification

Step 2





14

IGV PT Over Ride Control

Step 2

The final step in the static test

is to verify the PT over ride

function.

AFI the Npt_Speed (F8:123)CPT instruction in file 101 so

the data can be manually

increased.

Increase Ngp_Speed >102 and

verify that the calculated

GVPSIN_SCH drives the IGVclosed based on the

PTOVERDSLOP





15

Performance Issues

Low NGP, Early T5 Topping, and Low PCD

• Compressor Fouling-Dirt etc, Wash. A fouled compressor will have a loss in

airflow and efficiency.

• Bleed Valve Leak-Verify the bleed valve is not leaking ( Field certified Spit

Test)• External Compressor Leak- Feel around the flanges (using gloves) for

excessive air leaks (max 6 inch)

• Low NPT – check speed against optimum (EngPerf)

• Turbine Rub – Borescope





17

Operating Point

Step 3

Requires packageinstrumentation T1, Ngp, NPT,

T5, IGV angle

Requires GTPERF or

ENGPERF5 and PIPELINE

(Gas Compressors) for Analysis

GVAG_OFFST originally set at 0

is adjusted to optimize the fullload performance.

pdvsa igv control

Documents