Descarga Parcial de Cables - Conferencia Virtual
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1) The document discusses online partial discharge (PD) measurement of medium voltage and high voltage power cables to prevent unplanned outages. It describes PD theory, cable structures, sensors used for online PD detection, and case studies demonstrating the technology. 2) Qualitrol offers both portable and permanent online PD monitoring systems using sensors like high frequency current transformers and transient earth voltage sensors to detect PD pulses in energized cables. 3) Case studies demonstrate the system separating noise from PD signals to accurately detect and locate incipient faults in cables in high noise environments like GIS substations and switchgear.
Descarga Parcial de Cables - Conferencia Virtual
- 1. Prevent Unplanned Outages with On-line PD Measurement of MV/HV Power Cables Cable Partial Discharge Measuring Systems Ammar Khan Technical Application Specialist – Cables CBM 1Dated: June 21, 2016
- 2. • Partial discharge theory • Power cable structure • PD detection and localization • Why online PD measurement • Sensors used for online PD measurement • Qualitrol offerings • Case Studies Overview 2
- 4. • According to IEC 60270 Partial discharge (PD) is a localized electrical discharge that only partially bridges the insulation between conductors and which may or may not occur adjacent to a conductor. • The term ‘partial discharge’ includes a wide group of discharge phenomena – (i) internal discharges occurring in voids or cavities within solid or liquid dielectrics; – (ii) surface discharges appearing at the boundary of different insulation materials; – (iii) corona discharges occurring in gaseous dielectrics in the presence of inhomogeneous fields; – (iv) continuous impact of discharges in solid dielectrics forming discharge channels (treeing). What is Partial Discharge? 4
- 5. PD Phenomenon 5 HV across conductor PD Pulses Breakdown in cavity
- 6. The detection and measurement of discharges is based on the exchange of energy taking place during the discharge. These exchanges are manifested as: – (i) electrical pulse currents – (ii) dielectric losses – (iii) E.M. radiation (light) – (iv) sound (noise) – (v) increased gas pressure – (vi) chemical reactions Results of Partial Discharges 6
- 8. • Designed life of power cables is approximately 40 years • Cable Types that can be tested using Qualitrol Online PD Technology: – XLPE (Cross Linked PolyEthylene) – EPR (Ethylene Propylene Rubber) – PE (PolyEthylene) – PILC (Paper Insulated Lead Covered) Power Cable, its Basic Structure 8
- 9. A Power Cable Circuit 9 Joints Terminations Cross-bonding Links
- 10. Multi point grounding 10 Solid grounding
- 11. Distributed PD measurement 11 Zone 1 Zone 2 Zone 3
- 13. PD Detection into Cables 13 Long Cable Defect Measurement EndRemote End PD at Cable Terminations • PD in cable induces HF signals • The signals travel in both directions • Signals attenuate during propagation and reflect back at terminations • Detection Principle • Capture the HF signals emitted by PD at termination point • Analyse signals to identify PD fault and differentiate with Noise or External PD signals Long Cable Defect Measurement EndRemote End PD in Joints and inside the Cables
- 14. PD Fault Localization 14 • Time Domain Reflectometry (TDR) Principle is used to locate PD. Measure time difference between main and reflected HF signals (∆T) • For Longer cables, reflected pulse may not reach to the measurement end Requires a signal injector at the other end to inject same HF signal • For accurate localisation requires Accurate length of cable Cable Return Time (Tr) Long Cable Defect Measurement End Remote End ΔT Long Cable Measurement EndRemote End Tr
- 16. • No need to de-energize the cable system • Non destructive testing • Accurate Detection of Incipient Faults under operating conditions • Accurate Localization or Zoning of Incipient Faults • Trending Fault Severity via regular CHECKUPs • Helps in scheduling maintenance and planned outage • Ensure that cable is defect free after repair / workmanship Why Online PD Monitoring? 16 • Most of the incipient faults or defects in power cables generate PD signals well before the actual failure except water trees. • PD monitoring helps in identifying the incipient faults before the break down -> Saves cost of UNPLANNED OUTAGE
- 17. SENSORS USED FOR ONLINE PD MEASUREMENT 17
- 18. • HFCT (High Frequency Current Transformers) – To detect any PD signal coming from Cable insulation – One for each Cable – Installed at termination / joints • TEV (Transient Earth Voltage) – To detect any external PD signals coming from termination or nearby Switchgear Panel – One for each Termination – Installed near the openings or vents of terminations • RF Antenna (Radio Frequency) – For Noise gating – One for each Termination – Installed near to termination (Either TEV or RF Antenna) Sensors used for Online PD Measurement 18
- 19. • High Frequency Current Transformers – Inductive type sensor – Split core to install sensor easily – Different variants to fit the purpose (current (up to 1000A), diameter (up to 150mm internal diameter)) – Sensitivity: Up to 10mV / mA – Frequency Response: 200kHz – 15MHz • Installation requires – Individual cable earth – Cable insulation gland – Installation is done while the cable is energised Sensors: HFCT, Options for Installation 19
- 20. • Transient Earth Voltage Sensor – Capacitive type sensor – Integrated magnets help to attach it to metallic body – Sensitivity: Up to 100mV / V • Installation requires: – Metal Switchgear should not be double skinned / walled • RF Antenna – Can be used in place of TEV – Used to perform noise gating 20 Earthed metal clad TEV HFCT Vent Sensors: TEV and RF Antenna Installation
- 23. Online Cable PD Measurement Topology 23 Sensors (HFCT, TEV) Termination Portable System / Permanent Installation Sensors cables
- 24. QUALITROL OFFERINGS ON CABLE PD MEASUREMENT 24
- 25. Field Service 25 • Field Service •Sit Survey and feasibility of Online PD measurement •Risk Assessment •Method statement document shared with the customer •Testing of 6-9 cables per day •Detailed report with further recommendations within 5 days as standard or more days depending on the number of days of testing
- 26. Portable System 26 •Portable System (Periodic Measurement) •Main Unit (4 simultaneous channels) •Accessory Box •Sensors •Cables
- 27. Sensors 27 •High Frequency Current Transformers (HFCT) •Transient Earth Voltage Sensor (TEV) HFCT-150 1000A 3mV/mA HFCT-100 500A, 1000A 3-5mV/mA HFCT-60 50A, 500A, 5-10mV/mA HFCT-30 50A 10mV/mA
- 29. Continuous PD Monitoring Software 29
- 30. Continuous PD Monitoring Software 30
- 31. CASE STUDIES HIGH NOISE ENVIRONMENTS 31
- 32. Case Study 1: Lab Verification of Technology Maximum magnitude phase resolved distribution of mixed signals including noise, PD, interference were applied together to test the system and separated out by the system
- 33. Case Study 2: GIS Substation 33 Cable Termination GIS termination 220kV, XLPE Around 500m length Cable Termination Remote end Terminating to Overhead lines
- 34. Case Study 2: High Noise Environment 34 Before performing any filtering on Channel A single cycle data, high noise level and too much interference can be seen. Not sure which is PD or which is noise. Also not sure that there is any PD? After filtering, white noise level is decreased. Interference signals can still be seen at the same locations. However, some more pulses appeared in the middle. These pulses in the middle may or may not be PD
- 35. Case Study 2: Extracted Noise Pulses 35 Channel A noise pulse shape, its maximum magnitude phase resolved distribution and pulse count phase resolved distribution
- 36. Case Study 2: Extracted PD Pulses 36 Channel A PD pulse shape, its maximum magnitude phase resolved distribution and pulse count phase resolved distribution By TDR, it states that PD is located at remote end.
- 37. Case Study 3: Metalclad Switchgear 37 Cable Termination Metal clad 10kV, XLPE Around 1367m length One HFCT on the earth shield of cable Other two beneath the metal housing as earth shield was available there
- 38. Case Study 3: Interference and PD 38 Before performing any filtering on Channel A single cycle data, low noise level but too much interference can be seen. Not sure which is PD or which is noise. Also not sure that there is any PD?
- 39. Case Study 3: Extracted Noise Signals 39 Noise pulse shape, its maximum magnitude phase resolved distribution and pulse count phase resolved distribution
- 40. Case Study 3: Extracted PD Signals 40 Channel A PD pulse shape, its maximum magnitude phase resolved distribution and pulse count phase resolved distribution. By TDR, it states that PD is located at remote end.
- 41. Case Study 3: Extracted PD Signals 41 Channel C PD pulse shape, its maximum magnitude phase resolved distribution and pulse count phase resolved distribution
- 42. THANK YOU End of Session 42