06_C_3_Rotor_Earth_Fault_Protection.ppt
- 1. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 1 Training: Numerical Unit and Station Supply Protection Rotor Earth Fault Protection Presenter: Dr. Hans-Joachim Herrmann PTD EA13 Phone 0911-433-8266
- 2. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 2 in case of an earth fault, only small currents flow due to the galvanical isolation Problem: Double earth faults and interturn faults as a consequence of an earth fault cause: • magnetical unbalance • high currents at the fault location Task: Detection an earth fault already when it starts to build up Destruction of the Rotor Earth fault in the rotor RE CE Rotor Excitation system + - Stator Requirement for Rotor Earth Fault Protection
- 3. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 3 Excitation system + - Voltage Source „Earthing brush “ Coupling Unit Measuring - Incoupling of an AC voltage (50 Hz or 60 Hz) - Measuring of the earth fault current - Measuring of the earth fault resistance - Incoupling of low frequency square wave voltage Principles: Higher Sensitivity Protection Principle
- 4. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 4 Also IEE2 at 7UM62 possible IEE1 J7 J8 1B1 1B3 1A1 1A3 + - 4A1 4B1 3PP1336 Err. 2B1 7UM6 Connection on the phase to phase voltage 7XR61 100 V - 125 V AC 105 105 AC Voltage Source appr. 42V or 65V Documentation for Coupling Device in the Internet External resistors at excitation voltages > 150 V (circulating current >0,2A) Earth Current Measurement Connection
- 5. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 5 coordinated resonant circuit to fN >40V If disturbance influence from the excitation is to large IE Protection Pick-up limit: IE,Fault > IE,Dist... L1 L2 L3 IE,Distr. IE,Fault 4F 105 0,75H Connection on the earthing brush Earth Current Criterion Connection Principle (50 Hz/60Hz - Injection)
- 6. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 6 Z 50 ( ) 169.65 Z 60 ( ) 69.531 0 50 100 150 200 250 300 0 500 1000 1500 2000 Filterverhalten Bandpaß Frequenz in Hz Impedanz in Ohm Z f ( ) f mA 27 k 1,5 170 V 45 I R Z U I f Coupling Imax approx. 300 mA Gain Characteristic of the R, C, L-Circuit
- 7. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 7 Protection with two stages: Measuring circuit supervision mA 23 k 1,5 400 V 45 I R Z U I f Coupling ZCouplingl(50Hz) = 400 ZCouplingl(60Hz) = 335 Imax ca. 100 mA (voltage source decreases a little bit ) Protection Settings Earth Current Criterion
- 8. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 8 Earth Current Criterion Logic
- 9. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 9 100V 42V u Digital protection (7UM62) calculation of RE RE CE RV CK RV CK L1 L2 L3 i L1) 1) Recommended at static excitation with inject harmonics (3rd harm.; 6th harm.) Calculation of the Fault Resistance RE (at 50Hz/60Hz-Injection)
- 10. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 10 (1) (2) (3) (4) combining (3) and (4): Note: RV* and XK* are measured during commissioning Model: Zers ZMess Z X*K R*V XE RE V E 2 E 2 E 2 E E * R - , Z R X R X R R Z Z R Z j m e Mess I 2 E 2 E E 2 E K 2 E E 2 E E V - - j 2 ers X R X R * X X R X R * R Z K m 2 E 2 E E 2 E - , * X Z X R X R X I V V e 2 K m 2 E - e - - - , , , * R Z R * R Z R * X Z R R X R I Calculation Formula of the Fault Resistance RE
- 11. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 11 Earth Fault Resistance Calculation Logic
- 12. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 12 Measured during commissioning Measuring circuit supervision Measured current can be influenced by disturbances Correction during primary test, (in most case the alarm stage is concerned) Earth Fault Resistance Calculation Settings
- 13. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 13 Excitation + - CE RE Digital Protection (7UM62) UH RV RV Ucontrol Umeas. RM 7XR6004 Controlling device (7XT71) IE Measuring transducer RE Fault resistance RV Coupling resistor UH Auxiliary supply ( 50V) RM Measuring shunt resistor CE Rotor capacitance Basic Diagram: Injection of Square Wave Voltage with Low Frequency (1- 3 Hz)
- 14. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 14 Connection on the phase to phase voltage Exc. 17 15 11 25 + - 27 7XR6004 25 27 7UM62 7XT71 TD1 K14 K13 + TD2 K16 K15 + 40 k 40 k Control voltage Measuring voltage 100 V 110 V 120 V 9 7 Injection of Square Wave Voltage Connection Diagram 7UM62
- 15. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 15 RV 2 RE CE UH UM RM UH UM UM 50V - 50V 1,88V - 1,88V 0,75V - 0,75V t t t iE 50V 375 20k 2 H M V U R R E M M i R U E R 5k E R 0 M U E V 2 C R E M 1 ~ R U Equivalent circuit: Basic Principle: Injection of Square Wave Voltage with Low Frequency
- 16. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 16 Influence of field voltage and earth fault location a) Earth fault location Shifting of measuring voltage with a positive or negative dc voltage b) Jumps in the field voltage a change in the field voltage takes to jumps in the dc-voltage shifting Udc = dc voltage shifting Solution: Calculation of the difference voltage U = |UM1 - UM2| U1 = |UM1 - UM2| U3 = |UM3 - UM4| U2 = |UM2 - UM3| Solution: Block of measuring at jumps (e.g. DU1 = DU2) UM Udc Udc1 UM1 UM 2 UM3 UM4 UM1 UM 2 Udc2 UM Sources of Errors - Error Compensation
- 17. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 17 RE CE UH UM RM RV 2 UM U1 U2 Algorithm Voltage divider: Filtering: Amplitude-log frequency curve: fA = 800 Hz; N = 64 2 - 1 - 2 V M M H E M M E V M H R R U U R R R R R U U N N u N U u N U 1 i i 2, 2 1 i i 1, 1 1 ; 1 2 - : : 2 1 M U U U U 1 K K I I U U 8 1 k k U 8 1 U 0 30 60 90 120 150 180 210 240 270 300 0.001 0.01 0.1 1 f in Hz G(f) Continuity supervision: Validity requirement otherwise Calculation Formulas
- 18. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 18 Logic Diagram Rotor Earth Fault Protection (1-3Hz)
- 19. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 19 Measuring circuit supervision If the integrated test function is used, pick-up value of test resistor Advanced parameter only visible in DIGSI Earth Fault Resistance Calculation Settings (1-3 Hz Principle)
- 20. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 20 G RW RE CE EM ERT L+ RW UG RE CE L- (50/60 Hz) (1 - 3 Hz) (50/60 Hz) (1 - 3 Hz) 40k 4µF 4µF a) rotating diodes b) separate Exciter (static excitation) 40k Connection of the Rotor Earth Fault Protection
- 21. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 21 Chance of charge from rotor earth capacitance Disturbances by the excitation generator Generator with Rotating Excitation Fault Free Condition
- 22. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 22 Fault resistor is inverse proportional to the difference voltage Generator with Rotating Excitation Test Condition with a Fault Resistor
- 23. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 23 100V 45V CK;4µF CK;4µF RK;100 RK;100 RV;40k RV;40k RE 7UM62 7UM62 uControl uMeas. iREF uREF 7UM61 nur iREF oder 1- 3 Hz principle 50 Hz principle Parallel Operation of Rotor Earth Fault Protections
- 24. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 24 ( ) 20k 2 RV * K R * K C E R 2 ll : * V E E R R R 20k 2 * V E E R R R 4k * 5k E E R R Measurement 7UM61 or 7UM62 (RV is earthed for an AC voltage) Equivalent circuit: seen from the 7UM6, RV already is interpreted as a rotor-to-earth resistance Measurement: measured as a fault resistance Case 1: Case 2: alarm stage becomes less sensitive open brushes are not find out Parallel Operation of Rotor Earth Fault Protections
- 25. Energy Sector Copyright © Siemens AG 2008. All rights reserved. Siemens Power Academy TD 06 Rotor Earth Fault Protection Using numerical machine and motor protection Version: C 3_Page 25 RV 2 RE RM 2CK (8µF) Umeas U 2 Measurement 7UM62 (1- 3 Hz) (CK is earthed for a DC voltage) Equivalent circuit: seen from the 7UM6: high rotor capacitance capacitors will not be completely loaded U ~ RE -1 under no-earth-fault conditions a fault resistance is already measured alarm stage becomes less sensitive (approx. 50k) longer measuring time Parallel Operation of Rotor Earth Fault Protections