Travelling Wave Based DC Line Fault Location in VSC HVDC Systems - PowerPoint PPT Presentation

M.Sc. Thesis Presentation Travelling Wave Based DC Line Fault Location in VSC HVDC Systems K.P.A.N. Pathirana Department of ECE University of Manitoba Canada.

Outline  Introduction  Surge detection method  Modelling of Rogowski coil  Line fault location performance  Conclusion and future work

Background  HVDC transmission lines and cables need repairs quickly as possible after a fault.  Travelling wave based fault location is the common fault location method applied in HVDC transmission lines.  IGBT based voltage source converter (VSC) HVDC systems are gradually gaining ground.

Problem definition  No publications dealing with the fault location in VSC HVDC schemes with such long cable connections.  The large DC capacitance at the converter terminal.  Measurement bandwidth of the transducers.

Objectives  Development of a method of measurement for detecting travelling wave arrival times in a VSC HVDC scheme.  Testing and verification of the proposed measurement system through simulations.  Investigate the effect of different parameters on the accuracy of fault location.

Line fault location methods  Techniques based on impedance measurement  Techniques based on high frequency spectrums of the currents and voltages  Machine learning based approaches  Techniques based on travelling waves

Line fault location methods  Techniques based on impedance measurement  Techniques based on high frequency spectrums of the currents and voltages  Machine learning based approaches  Techniques based on travelling waves

Travelling wave based fault location 𝑌 𝐺 = 𝑚 − 𝑣 . ( 𝑢 𝐷𝐷 − 𝑢 𝐷𝐷 ) 2

Current LFL technology  Detection methods

Current LFL technology  Detection methods  Time stamping

Current LFL technology  Detection methods  Time stamping  Typical accuracies

Line Termination in LCC and VSC Schemes LCC HVDC VSC HVDC

Travelling waves incident on junction

Travelling waves incident on junction 𝑤 𝑠 𝑦 𝑝 , 𝑢 = 𝜍 . 𝑤 𝑦 𝑝 , 𝑢 𝑤 𝑢 𝑦 𝑝 , 𝑢 = 𝜐 . 𝑤 𝑦 𝑝 , 𝑢 𝜍 = 𝑎 𝑑𝐷 − 𝑎 𝑑𝐷 𝑎 𝑑𝐷 + 𝑎 𝑑𝐷 2 𝑎 𝑑𝐷 𝜐 = 𝑎 𝑑𝐷 + 𝑎 𝑑𝐷

Travelling waves incident on junction 𝑀 𝑎 𝑑𝐷 = 𝐷 → ∞ 𝑎 𝑑𝐷 = 𝑎 𝑑𝑑𝑑𝑑𝑑 𝜍 = 𝑎 𝑑𝐷 − 𝑎 𝑑𝐷 𝜍 → 1 𝑎 𝑑𝐷 + 𝑎 𝑑𝐷 𝑤 𝑝 𝑦 𝑝 , 𝑢 = 1 + 𝜍 . 𝑤 𝑦 𝑝 , 𝑢 𝑤 𝑦 𝑝 , 𝑢 = 𝐵𝐵 − 𝑦 𝑝 −𝛽𝑢

Travelling waves incident on junction 𝑀 𝑎 𝑑𝐷 = 𝐷 → ∞ 𝑎 𝑑𝐷 = 𝑎 𝑑𝑑𝑑𝑑𝑑 𝜍 = 𝑎 𝑑𝐷 − 𝑎 𝑑𝐷 𝜍 → 1 2 𝑎 𝑑𝐷 + 𝑎 𝑑𝐷 V(Xo,t) Voltage magnitude 1.6 Vo(Xo,t) 𝑤 𝑝 𝑦 𝑝 , 𝑢 = 1 + 𝜍 . 𝐵𝐵 − 𝑦 𝑝 −𝛽𝑢 1.2 0.8 𝑤 𝑦 𝑝 , 𝑢 = 𝐵𝐵 − 𝑦 𝑝 −𝛽𝑢 0.4 0 0 2 4 6 8 Time [S]

Travelling waves incident on junction 𝑀 𝑎 𝑑𝐷 = 𝐷 → 0 𝑎 𝑑𝐷 = 𝑎 𝑑𝑑𝑑𝑑𝑑 𝜍 = 𝑎 𝑑𝐷 − 𝑎 𝑑𝐷 𝜍 → -1 𝑎 𝑑𝐷 + 𝑎 𝑑𝐷 𝑤 𝑝 𝑦 𝑝 , 𝑢 = 1 + 𝜍 . 𝑤 𝑦 𝑝 , 𝑢 𝑤 𝑦 𝑝 , 𝑢 = 𝐵𝐵 − 𝑦 𝑝 −𝛽𝑢

Travelling waves incident on junction 𝑀 𝑎 𝑑𝐷 = 𝐷 → 0 𝑎 𝑑𝐷 = 𝑎 𝑑𝑑𝑑𝑑𝑑 𝜍 = 𝑎 𝑑𝐷 − 𝑎 𝑑𝐷 𝜍 → -1 𝑎 𝑑𝐷 + 𝑎 𝑑𝐷 2 𝑤 𝑝 𝑦 𝑝 , 𝑢 = 1 + 𝜍 . 𝐵𝐵 − 𝑦 𝑝 −𝛽𝑢 Voltage magnitude V(Xo,t) 1.6 Vo(Xo,t) 𝑤 𝑦 𝑝 , 𝑢 = 𝐵𝐵 − 𝑦 𝑝 −𝛽𝑢 1.2 0.8 0.4 0 0 2 4 6 8 Time [S]

Test network

Terminal voltage 205 200 Voltage [kV] 195 190 No inductor 185 0.595 0.598 0.601 0.604 Time [S]  Solid P-G fault 70 km away from Converter-1

Terminal voltage  Gradual Change 205 200 Voltage [kV] 195 190 No inductor 185 0.595 0.598 0.601 0.604 Time [S]  Solid P-G fault 70 km away from Converter-1

Terminal voltage 205 200 Voltage [kV] 195 190 No inductor 1 mH inductor 185 0.595 0.598 0.601 0.604 Time [S]  Solid P-G fault 70 km away from Converter-1

Terminal Current No inductor 0.6 1 mH inductor 0.3 Current [kA] 0 -0.3 -0.6 0.595 0.598 0.601 0.604 Time [S]  Solid P-G fault 70 km away from Converter-1

Terminal Current  Less sharp terminal Current No inductor 0.6 1 mH inductor 0.3 Current [kA] 0 -0.3 -0.6 0.595 0.598 0.601 0.604 Time [S]  Solid P-G fault 70 km away from Converter-1

Problems with line voltage and current measurements  Transducers need to be installed at very high potentials.  Insulations requirements.  Electrical isolation between sensor output and the data acquisition system.  Bulky and expensive instrumentation.

Surge capacitor current  Rate of change of terminal voltage 0.01 Current [kA] -0.01 -0.03 -0.05 No inductor 1 mH inductor -0.07 0.6001 0.6003 0.6005 0.6007 0.6009 Time [S]  Solid P-G fault 70 km away from Converter-1

Rate of change of the surge capacitor current  Small effect on value of inductance Rate of change of surge capacitor current No Inductor 9000 1 mH 10 mh 4000 -1000 0.6004 0.6005 0.6006 Time [s]  Solid P-G fault 70 km away from Converter-1

Proposed termination Inductor Converter Cable Side side Surge Capacitor Rogowski Coil v r

Experimental results  Dorsey converter station  LCC HVDC Inner radius 260 mm  ± 500 kV Outer radius 284 mm  900 km Overhead line Resistance 468 Ω 0.5 H Self-Inductance 3.5 mH Converter Cable Side side Capacitance 60.93 pF 55 nF Mutual-Inductance 0.55 µH Rogowski Coil v r

Experimental results 6 Rogowski coil voltage [V] 5 4 3 2 1 0 -1 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 (a) Time [ms] -3 x 10 2 Rogowski coil voltage [V] 1.5 1 0.5 0 -0.5 -1 -1.5 -2 -2.5 -3 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 (b) Time [ms]  Rogowski coil voltage for a fault 356 km away from Dorsey converter station.

Remarks  If there is no series inductor  voltage or surge cap cannot be used  Current can be used  With series inductor  voltage or surge cap can be used  The value of the series inductor is not that important as long as it is above 1 mH.

Modelling of Rogowski Coil � 𝐼 ( 𝑢 ). cos 𝛽 . 𝑒𝑦 = 𝑗 𝑞 ( 𝑢 ) − 𝑂 𝑡 . 𝑗 𝑡 ( 𝑢 ) 𝑒𝑒 = 𝐵 . 𝑂 𝑡 𝑚 𝑒𝑦 . 𝜈 0 . 𝐼 ( 𝑢 ). cos( 𝛽 )

Modelling of Rogowski Coil 𝑒 ( 𝑢 ) = 𝜈 0 . 𝐵 . 𝑜 . 𝑗 𝑞 ( 𝑢 ) 𝑚 . 𝑒𝑗 𝑞 ( 𝑢 ) 𝐵 ( 𝑢 ) = − 𝑒𝑒 ( 𝑢 ) = −𝜈 0 . 𝐵 . 𝑂 𝑡 𝑒𝑢 𝑒𝑢

Equivalent Circuit of Rogowski Coil 𝑤 𝑠 𝑢 = 𝐵 ( 𝑢 ) − 𝑀 . 𝑒𝑗 𝑢 − 𝑗 𝑢 . 𝑆 𝑒𝑢 𝑗 𝑢 = 𝐷 . 𝑒𝑤 𝑠 𝑢 + 𝑤 𝑠 𝑢 𝑒𝑢 𝑎 𝑑

Parameters of the designed Rogowski coil Inner radius 51.37 mm Outer radius 57.49 mm Number of Turns 870 measured calculated Resistance 4 Ω 3.9 Ω Self-Inductance 81 µH 81 µH Capacitance * - 13 pF Mutual-Inductance 0.093 µH 0.093 µH * Capacitance is too small to measure

Test setup

Verification of the Rogowski coil model 40 20 Current [A] 0 -20 Current Through the Rogowski coil -40 -0.05 -0.01 0.03 0.07 0.11 0.15 0.19 0.23 0.27 0.31 0.35 0.39 Time [mS] 3 1 Voltage [V] -1 Simulated Experimental -3 -0.05 -0.01 0.03 0.07 0.11 0.15 0.19 0.23 0.27 0.31 0.35 0.39 Time [mS]

Verification of the Rogowski coil model 40 20 Current [A] 0 -20 Current Through the Rogowski coil -40 -0.05 -0.01 0.03 0.07 0.11 0.15 Time [mS] 3 1 Voltage [V] -1 Simulated Experimental -3 -0.05 -0.01 0.03 0.07 0.11 0.15 Time [mS]

Line Fault Location Performance

Line Fault Location Performance

Terminal voltages and Currents Positive pole Negative pole -170 Con. 1 200 Voltage [kV] Voltage[kV] Con. 2 -190 180 Con. 1 -210 Con. 2 160 600 601 602 603 600 601 602 603 (a) Time [mS] (b) Time [mS] 1.5 1 1 0.5 Current[kA] Current[kA] 0.5 0 0 -0.5 Con. 1 Con. 1 -0.5 -1 Con. 2 Con. 2 -1 -1.5 600 601 602 603 600 601 602 603 (c) Time [mS] (d) Time [mS] solid pole-to-ground fault on positive pole 130 km from Converter-1

Surge Capacitor currents and Rogowski coil Voltages Positive pole Negative pole 0.02 0.07 Con. 1 Current[kA] Current[kA] Con. 2 -0.01 0.04 -0.04 0.01 Con. 1 Con. 2 -0.07 -0.02 600 601 602 603 600 601 602 603 (e) Time [mS] (f) Time [mS] 1 1 0.5 Con. 1 0.5 Voltage[V] Voltage[V] Con. 2 0 0 -0.5 -0.5 -1 Con. 1 -1 -1.5 Con. 2 -2 -1.5 600 601 602 603 600 601 602 603 (g) Time [mS] (h) Time [mS] solid pole-to-ground fault on positive pole 130 km from Converter-1

Threshold setting