31 October 2013

Monitoring in Rotating Machines

Maik Koch, Omicron Berlin 1. Motivation 2. Source separation 3. System design 4. Measurement results

Failure Statistics

Source: Brütsch et al. "Insulation Failure Mechanisms of Power Generators", DEIS July/August 2008

Dielectric; 56%

Mechanical; 27%

Thermal; 17%

• Temperature

• Electrical field

• Ageing, moisture, aggressive substances

• Mechanical vibrations

Reasons for Partial Discharges

31 October 2013

Monitoring of Rotating Machines

Maik Koch, Omicron Berlin 1. Motivation 2. Source separation 3. System design 4. Measurement results

surface endwinding discharge - M

End winding surface - contamination - M

Slot discharge, semicon. paint abrasion - H

Insufficient Spacing, Sparking, Contact, Corona, - M

Micro voids - L

Delamination from conductor - H Delamination of

tape layers - H

S3

E1 & E2

PD Sources in Stator Insulation

E1 & E3

S1 & S2 & S4

A)Covering Tape B) Spacer, Coil-End Bracin C) Mica Tapes D) Grading/ Coating E) Semiconductive Coating F) Inner Semicon. coating G) Turn Insulation H) Slot Wedge / Seal I) Stator Core

Class Name Symmetry Shape Phase angle Magnitude Description

Degree of hazard for insulation

S1 Delamination winding -

main Insulation from conductor

Asymmetric, higher density and magnitude in positive

half wave of AC voltage.

distinct triangular shape with a sharp rise around the

positive voltage zero.

Start 300°- 360° >S4

decrease with load/ temperature:

insulation expands closing of

delaminations

void between inner conductor and insulation,

better measurement in lower freq. range

HIGH Peak 0-60°

>S4

Increase with load wedge loosens,

overhangs loose, bar vibration

Stop 90°- 150°

S2 Delamination of tape layers Symetric sickle shaped

(shape depends on y-Axis scaling) mostly mixed with „G“

Start 120°- 210° 300°- 30°

>S4 bigger symmetrical inner

micro void, start of delamination

HIGH Peak /

Stop /

S3 Slot discharge, semicon paint abrasion

Asymmetric, higher density and magnitude in negative half wave of AC

voltage.

distinct triangular shape with a sharp rise around the

negative voltage zero.

Start 120°- 180° can increase with load >S4 (about 10 nC)

void between stator/ slot iron and insulation caused

by vibration of the bar/ coil in the slot

HIGH Peak 180° - 240°

Stop 270° - 330°

S4 Micro voids Symmetric , large amount of impulses

Large amount of impulses, lower amplitude, shape follows

the gradient of the voltage, also wave like pattern

Start 270°-0° 90°- 180°

normal small air pockets, healthy insulation system LOW Peak

30°-90° 210°- 270°

Stop 90° - 180°

270° - 360°

E1 End winding surface discharge - contamination Symmetric

Pattern looks like “rabbit ears”, mostly mixed with “S4”, high

amplitude

Start ~30° ~210°

>>S4

Surface discharge/ tracking in enwinding section

MEDIUM Peak /

Stop /

E2 Insufficient Spacing,

Tracking, Sparking, Contact, Corona, Floating Potential

Corona – Asymmetric: higher amplitude in one

or another AC cycle horizontal patterns, also

multiple levels, higher amplitude

“center” Corona

90° 270°

>>S4 (>50 nC)

all kind of corona, floating potential, sparking. can be between the winding but

also from contact or sharp edges, difficult to

distinguish

MEDIUM „center“

Sparking / contact

30° 210° Sparking - Symmetric

E3

Connection area between slot corona protection and

end winding corona protection, surface

endwinding discharge

Asymmetric, higher density and magnitude in negative half wave of AC

voltage.

compared to slot discharges the triangular shape is

more oriented to the voltage maximum also can be similar like “E1” one “rabbit ear” in

negative AC cycle

Start 120°- 180°

>S4 (10 – 50 nC) Discharge in enwinding

section due to bad contact between AGS and EGS

MEDIUM Peak 210° - 270°

Stop 270° - 330°

PD Sources and Their Criticality

Excitation Tyristor – 6 Peaks also 12 and 24 peaks

Disturbances

Background Noise and Disturbances - asynchronous with AC

Disturbances

Delamination winding - main Insulation from conductor – void between inner conductor and insulation

S1 high

Slot discharge, semicon paint abrasion - void between stator/ slot iron and insulation

S3 high

Delamination of tape layers - bigger symmetrical inner micro void

S2 high

Connection area between slot corona protection and end winding corona protection, surface endwinding discharge

E3 medium

Inner PD + Endwinding surface discharge - contamination

E1 medium

Insufficient Spacing, Tracking, Sparking, Contact, Corona, Floating Potential

E2 medium

Inner PD + End winding surface discharge - contamination

E1 medium Micro void - different scaling

S4 low

Micro void – different scaling

S4 low

Micro void

S4 low

Insufficient Spacing, Tracking, Sparking, Contact, Corona, Floating Potential

E2

E3 medium

Connection area between slot corona protection and end winding corona protection, surface endwinding discharge

Slot discharge, semicon paint abrasion - void between stator/ slot iron and insulation

S3 high

Inner PD + End winding surface discharge - contamination

medium E1 medium

The Challenge: Source Separation

Background Noise and Disturbances - asynchronous with AC

Disturbances

200 pC

Inner PD + End winding surface discharge - contamination

E1 medium

900 pC

Delamination of tape layers - bigger symmetrical inner micro void

S2 high

500 pC

1,4 nC

Q

time

Alarm

CORE

L1 L2

L3 neutral

3 2 1 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 36 35 34 33 32

E E

H

TE

Coupling between Phases

> 2013-10-31

10/31/2013 Page: 10 © OMICRON

Separation with 3PARD

> 2013-10-31

cluster 4

cluster 9

cluster 6

3PARD

10/31/2013 Page: 11 © OMICRON

Back Transformermation to PRPD

Supervised Learning

Feature Selection

Classification

Classification

Class (PD source/no PD source)

Classifier Training

Learning informa-

tion

Feature Extraction

Feature Selection

PRPD Reference Database

Probability based

Decision Tree Generation

Decision making

Rule bases

Feature Choice

Feature Extraction

Feature Extraction

Categorization of feature values

Tree Adjustment

CART Framework

Feature Choice

Feature Extraction

Categorization of feature values

Tree Descent Decision Rules

Combination of classification results - PD expert‘s work

PRPD Data Collection

Manual Feature

Definition

Page 12 © OMICRON

Pattern Recognition

Page 13 © OMICRON

PRPD Pattern Classification Report (example)

31 October 2013

Monitoring of Rotating Machines

Maik Koch, Omicron Berlin 1. Motivation 2. Source separation 3. System design 4. Measurement results

PDM 600-3 Module

Monitoring Server

Controller MCU 502 with Relais

19‘‘FO Patchpanel

FO < 1000 m

Triaxial cable < 20m

Coupling capacitor MCC 124 / 112

Monitoring System OMS600

Page: 16 10/31/2013

Coupling Capacitors MCC 124 / MCC112

> 10/31/2013

System Configuration Multiple Generators

Temporary Monitoring

> One case for easy transport > “Plug and Play” (pre-wired) > IP65 (NEMA 4)

Fixed monitoring vs. Portable monitoring OMS 600 OMS 605

Browser based Monitoring Software All measurement systems System per Asset

Configuration User-Settings

Live Trend

20

Historical Data

21

31 October 2013

Monitoring of Rotating Machines

Maik Koch, Omicron Berlin 1. Motivation 2. Source separation 3. System design 4. Measurement results

Customer Project BASF Power Plant Ludwigsburg

First contact BASF-OMICRON: April 2011

Offer, negotiations: 18. Mai 2011

Installation, commissioning Generator 1: 25./26. Mai 2011

Training: 05. Juli 2011

Installation, commissioning Generator 2: 8./9. August 2011

Weekly reports

+ ARGOS

Monitoring System Hardware

24

Material & Components

2 OMS 600

1 Monitoring Server, Monitoring Software

1 UMTS Router

Use of existing PD couplers

Commissioning Generator Nr.1

Surface discharge, Phase U_> 9,4 kV

25

Monitoring Generator Nr.1

Surface Discharge Phase U

Phase U − Phase V − Phase W −

26

Monitoring of Generator 2

27

28

Reports by Omicron Experts

Summary

On-line monitoring provides results under real operating conditions

Source separation

System design

Diagnosis SW

Monitoring SW

Until now about 50 Installations