1Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

ASSESSMENT OF PROTECTION SCHEMES: A KEY FACTOR FOR RELIABILITY

Alain SCHENK

David ORZAN

Fritz GANTENBEIN

Markus VON ARX

BKW FMB Energy Ltd.Switzerland

BE

JU

BL

SO

NE

2Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Assessement of protection: Why ?

Liberalization Cost reduction High quality of supply (reliability) risk management, condition based maintenance Less security margin More faults are expected than

before

New possibilities improve the reliability of protection Numerical relays (new schemes for specific situations) Calculation programs Testing devices

3Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Numerous network configurations

Systematic study of main and back up protection reliability

Best compromise for relay settings (selectivity vs. security)

Overview of the protection reliability of the whole system

Relay operation check

Relay settings and behaviour check (with transient signals)

Feasibility studies (simulation of different configurations)

Better understanding

Case Studies Simulation for a multiterminal line Dynamic Relay testing with a fault recorder event Fault between 16 Hz 2/3 and 50 Hz systems

Assessement of protection: How ?

Tools Event of fault recorders Periodic relay testing Calculation programs Dynamic relay testing

4Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Simulation for a mutliterminal line

Problems Relatively short line (15 km)

selectivity High short circuit currents and quite

well interconnected network No signalling equipment Inhomogeneous lines Industrial plants

own generation capabilities or supply by other networks

T

A

B

5Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

T

A

B

C

T

A

B

C

Simulation for a mutliterminal line

With embedded generator

(Industry customer)

Without embedded generator

(Industry customer)

6Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Transient simulations results

Problem

Dynamic relay testing

Fault recorder events

Incorrect relay operation Did the relay maloperate or were

the settings incorrect ? check of relay behaviour check of relay settings

7Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Dynamic relay testing

Current

Voltage (faulted phase)

Voltage (healthy phase)

Unstable operation of the relay could be confirmed

Earth fault in an isolated neutral network (50 kV)

8Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Dynamic relay testing

50 Hz

16 Hz 2/3

50 Hz and 16 Hz 2/3 on the same tower Does the relay trip when a short circuit

occurs between the two systems ?

Transient simulations results

simulation of events check of relay settings

Problem

9Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Dynamic relay testing

0.00 0.05 0.10 0.15 0.20 0.25 0.30[s]

-30

-20

-10

0

10

20

30

[kA] Earth contact

Tripping unreliable without earth contact teleprotection

0.00 0.05 0.10 0.15 0.20 0.25 0.30[s]

-30

-20

-10

0

10

20

30

[kA]

10Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper

Barcelona 12-15 May 2003

Conclusion

Situation Protection assessment is necessary because of the

reduced security margin due to cost pressure Protection assessment can be significantly improved

through simulations and dynamic testing

Advantages of the proposed approach Reduced investigation time low cost Consideration of all scenario and aspects high

quality Study of complicated situations deep

understanding