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

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

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

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

Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper Barcelona May T A B C T A B C Simulation for a mutliterminal line With embedded generator (Industry customer) Without embedded generator (Industry customer)

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

Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper Barcelona May 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)

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

Alain Schenk, Switzerland, ALPHA 3, Block 3.1, Selected paper Barcelona May Dynamic relay testing [s] [kA] Earth contact  Tripping unreliable without earth contact  teleprotection [s] [kA]

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