Essent_Case_Study_2006.pps

Distribution Europe, BarcelonaMei 18, 2006.

Agenda of this presentation

• Introduction to Essent and the Essent Medium Voltage Distribution Network

• Structure of the Essent Medium Voltage Distribution Network.

• Downtime in the distribution network: Causes and solutions.

• Solutions for enhancing the reliability of the distribution network.

• Implementation of Cable Revitalisation project.• Special issues encountered during the project. • Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.




• Structure of the Essent Medium Voltage Distribution Network. • Downtime in the distribution network: Causes and solutions.• Solutions for enhancing the reliability of the distribution network. • Implementation of Cable Revitalisation project.• Special issues encountered during the project. • Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.


1. Die Essent-Gruppe im Überblick

Provinces

74%

Municipalities 26%

Turnover € 7,413 Mil.

Sales Power 52.1 TWh

Production capacity ca. 5,000 MW

Sales Gas 115.3 TWh

Employees 11,181

Key figures Essent (2004)

Shareholders

Essent is the largest Dutch Utility

Production, trading, distribution and sales of electricity

Trading, distribution and sales of gas including gas storage

Largest producer of green electricity in The Netherlands

Outside home market participations in Germany and Belgium

Cable networks for radio / TV, broadband and telephony

Activities Essent


Power• 2,500,000 connections

• 3,000 km HV

• 140,000 km MV / LV

• 50,000 transformer stations

• 22.5 min loss of load per year

Essent Netwerk is responsible for the power and gas grids of Essent

Gas• 1,750,000 connections

• 20,000 km high and low pressure

• 25,000 stations





• Downtime in the distribution network: Causes and solutions.• Solutions for enhancing the reliability of the distribution network. • Implementation of Cable Revitalisation project.• Special issues encountered during the project. • Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.


Medium Voltage Transport Grid.Medium Voltage Distribution Grid

Cables PILC 40.000 kmXLPE 6.500 km

overhead lines 0.0 m

90% = 10 kV 10% = 20 kV

The Essent MV Grid is devided into two sections:


GRID MODEL

Prim. OMT 0,25

Prim.OMT 0,25

Prim. OMT 0,5

OMT 1

OMT 1

E5

D4

C3 B2

Net 5

Trafo7

Trafo6

Net 1 Net 2 Net 3 Net 4

Net 6 Net 7 Net 8

Net 24

OMT 1

Net 23 Net 25 ZO 600kVA

OMT 1

OMT 1

VNet 10 Net 11

Net 14

Net 12 Net 15 Net 16 Net 17

Net 18 Net 19 Net 20 Net 21 Net22

G

150/110 kV

10 kV

1

2

Mainstation

HV/MV

DIFF+OMT1,5

DIFF+OMT1,5

DIFF+OMT1,5

DIFF+OMT1,5

DIFF

DIFF

DIFF

DIFF

Substation MV/MV


The Essent MV Transport Grid

cable length varies from 1 to 15 km

Grid is 100% maze formed. Is operated under N-1 redundancy conditions

Every substation MV/MV feeds one or more distribution feeders or is a industrial customer.

Substation MV/MV

A B C

E

F G

HV/MV

Substation MV/MV

Substation HV/MV


Why this structure

Cost effective: needs less expensive HV/MV substations

more reliable: semi long MV distance transport is N-1 safe

butprotection system: more complicated

Overall:

We think this is the best solution:

highest reliability at the lowest costs



• Introduction to Essent and the Essent Medium Voltage Distribution Network• Structure of the Essent Medium Voltage Distribution Network.

• Downtime in the distribution network: Causes and solutions.

• Solutions for enhancing the reliability of the distribution network. • Implementation of Cable Revitalisation project.• Special issues encountered during the project. • Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.


Causes

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ing

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Downtime Causes


Components

0

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100

150

200

250

300

350

400

450

PIL

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ral

PILC 46%40.000 km

XLPE 5%6.500 km

JOINTS 28%140.000




• Structure of the Essent Medium Voltage Distribution Network. • Downtime in the distribution network: Causes and solutions.

• Solutions for enhancing the reliability of the distribution network.

• Implementation of Cable Revitalisation project.• Special issues encountered during the project. • Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.


Enhancing the reliability

1. Reduce amount of faults2. Reduce consequences of faults

Introduction of Condition Based Maintenance

Development of new protection philosophy:Recalculation and readjustment of all relay settings

Educate all personnel: Main Focus: Operational Personnel

This has mainly effect on item 2: Consequence Reduction


Actions to reduce the amount of faults

• Introduction of KLIC. This is The Netherlands National Cable and Pipeline Information Center. This forces all contractors to get information of the location of cables and pipes.

• Introduction of more diagnostics to determine the condition of cables and joints like PD, DS, tan

Main question:If you know the condition is bad how to repair ?Lets focus on XLPE



• Introduction to Essent and the Essent Medium Voltage Distribution Network• Structure of the Essent Medium Voltage Distribution Network. • Downtime in the distribution network: Causes and solutions.• Solutions for enhancing the reliability of the distribution network.

• Implementation of Cable Revitalisation project.

• Special issues encountered during the project. • Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.


This is the cable we are talking about

multi wire core

primary insulation (XLPE)

graphite semi conductor

copper shieldPVC cover

impregnated paper


Cable is not waterproofLeads to water tree forming and all other

troubles such as electrical tree

electrical tree

water treeand finally a break down


• new cables should be water-proof• existing cables ?

2. What can we do if the cables have many water trees?1. Wait for breakdown en then repair2. Use diagnostics to find water tree and electrical

tree. After that repair the affected places3. Replace whole cable

4.Repair cable by CableCURE

1. How can we prevent forming of water trees?


1. The condition and ability of the cable to support the required flow and pressure will be tested

2. The fluid is injected into the cable

3. The fluid rapidly diffuses from the strands

into the insulation

The CableCURE revitalization process 1


4. where it polymerizes with the water in the microvoids and fills them with a dielectric fluid. Since the molecules of the resulting dielectric fluid are much larger than water molecules, they lock into place, retarding the growth of future water trees.

5. The cable is tested with 0,1 Hz method

6. The cable is re-energized

The CableCURE revitalization process 2


How does the CableCURE treatment workPress impregnation fluid (patented Silicone based solution) into the multi wire core

Fluid will diffuse into the XLPE and reaches the outer side after some time

Fluid will on its way react with water and fills up existing cavities

Results:1. growth of water trees stops2. isolation is repaired3. new incoming water will not form water trees


All joints must be replaced The fluid has to pass the joint


Cable injection adapters must be placed

The termination has to be opened

A valve is placed and de termination recovered

* Latest developments: injection through termination connector


HV/MV

All cables are 3 x 1 x 400mm2 year 1978All cables are 150 mm2 AL PILC

2350 m 480 m

6741 m 319A

6740 m 319A

7985 m 305A

First this cable was replaced

After that this cable is impregnated

In 1996 this grid had 4 faults per year We expect max. 0,4

This grid transports 17 MW. It provides electrical power for 9.000 customers and some industries.It is N-1 safe

The main goal for action is not to decrease the average CML of the whole grid but prevent a disaster

for this particular grid.


Some impressions


• After first treatment we waited for 6 months because we wanted to be sure the treatment was a success.

• In this period no fault should have occurred, and no fault occurred

• After this period all the remaining XLPE cables of the shown Grid were treated.

• And because the treatment was successful 8 similar Grids followed.

Results of first project phase:




• Structure of the Essent Medium Voltage Distribution Network. • Downtime in the distribution network: Causes and solutions.• Solutions for enhancing the reliability of the distribution

network. • Implementation of Cable Revitalisation project.

• Special issues encountered during the project.

• Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.


1. Form a special team to perform the job.

2. Measure the cables before deciding on

treatment.

3. Impregnation pressure not to high. Max 4 bar.

Max length up to 5 km, and be patient.

4. After treatment you also should be patient

and not re-energise too soon.

Special issues





• Downtime in the distribution network: Causes and solutions.• Solutions for enhancing the reliability of the distribution

network. • Implementation of Cable Revitalisation project.• Special issues encountered during the project.

• Results of the Cable Revitalisation project. • Main developments in the Essent Distribution network.


1. Between 1999 and 2002 158.930 meter

path-length of XLPE-cables have been

revitalized

2. All cables were 400 mm2: age up to

1980

3. 749 joints were replaced

The Essent South project


• After one year the isolation is even better as it was original when the cable is new

• In the pilot grid there was just 1 fault up to now (in 6 years)• Overall the faults has decreased enormously. There is no

difference with new generation XLPE cable anymore

Results


Measured Results:CML 5 year average MV

0

2

4

6

8

10

12

14

16

18

20

1996-2000 1997-2001 1998-2002 1999-2003 2000-2004 2001-2005 2005

in 2005 12 minutes

just 9 minutes in southern region




• Structure of the Essent Medium Voltage Distribution Network. • Downtime in the distribution network: Causes and solutions.• Solutions for enhancing the reliability of the distribution

network. • Implementation of Cable Revitalisation project.• Special issues encountered during the project. • Results of the Cable Revitalisation project.

• Main developments in the Essent Distribution network.


Project: Revitalisation Network North.

We have to examine approx. 500 km cable

All types: from 3x1x70mm2 up to 3x1x630mm2

In order to keep the CML low


Project: PDOL Partial Discharge On Line

This is a project in co-operation of all the Dutch utilities, TUE and KEMA

The objective is that any failure in its most early phase should immediately notify us of its existence and tell its location, in order to be able to repair it before a breakdown occurs.

In order to decrease the CML


Other Topics.

• Increase cabling HV-grid (EM-radiation

standard)

• Increase expected cable-lifespan

• Method for identification and location of cables

in the field by GPS


Thank you for your attention !

Essent_Case_Study_2006.pps

Documents

essent distribution

distribution feeders

essent mv grid

key figures essent

telephony activities

gas grids of essent

andr postma essent netwerk

trafo7 trafo6 net