Анализ возможностей регистрации однофазных замыканий на землю в кабельных линиях с изолированной или компенсированной нейтралью при помощи оптоволоконных систем

А.Н.Лубков, В.В.Титков, П.Д.Тукеев , В.С. Баранцев

Политехнический университет Петра ВеликогоСанкт-ПетербургРоссия

A possibilities phase earthing detection in power transmission cable lines with insulated or compensated neutral by optic fiber temperature sensor

Alexander Lubkov, Vasiliy Titkov, Paul Tukeev and Vladislav Barantsev

Peter the Great Polytechnical University Saint PetersburgRussia

Power cable Distributed temperature sensor (DTS)

Cable Opto fiber placement

Dendrid propagation

Mini arc in cable insulation

encapsulated arc modelArc pressure (pressure by Thruton law)

ΔH - molar polymerization energy

Neutral gas concentration

Plasma conductivity

Electron scattering section

ionsneutrals

Ionasation degree

Joule heating of arc channel

Pw=P=nkT

Ethylene plasma analysis

1) C2H4→C2H2+H2

2) C2H2+H2→ C2H4

3) С2H2→C2H+H4) С2H→C2+H5) С2→C+С6) C+С→ С2

7) H2→H+H8) H+H→ H2

Thermal destruction

Ionization

𝑛𝑖𝐶𝑛𝑒′

𝑛𝐶=𝑔𝑖𝐶𝑔𝑒𝑔𝐶

∙(2𝜋𝑘𝑇𝑚𝑒)

3/2

ℎ3∙ 𝑒

−𝑊𝑖𝐶𝑘𝑇

𝑛𝑖𝐻𝑛𝑒′

𝑛𝐻=𝑔𝑖𝐻𝑔𝑒𝑔𝐻

∙(2𝜋𝑘𝑇𝑚𝑒)

3/2

ℎ3∙ 𝑒

−𝑊𝑖𝐻𝑘𝑇

𝑛𝑒′ = 𝑛𝑖𝐶 + 𝑛𝑖𝐻

𝑛𝑖𝐶 + 𝑛𝐶 = 𝑛𝐶0𝑛𝑖𝐻 + 𝑛𝐻 = 𝑛𝐻0

Ionization degree

6

𝛾 =𝑥 ∙ 𝑒0

2

3 ∙ 𝑘 ∙ 𝑇 ∙ 𝑚𝑒 ∙ α1 + α2 + α3 ∙ 𝜎𝑀 + α4 ∙ 𝜎𝐶2 + α5 ∙ 𝜎𝐻2 + α6 ∙ 𝜎𝐶 + α7 ∙ 𝜎𝐻 + α8 + α9 ∙ 𝜎𝐼

САНКТ-ПЕТЕРБУРГСКИЙ ПОЛИТЕХНИЧЕСКИЙ УНИВЕРСИТЕТ ПЕТРА ВЕЛИКОГО

7

𝑄 =𝑙 ∙ 𝐼ОЗЗ

2

𝜋 ∙ 𝑎2 ∙ 𝛾+ 2 ∙ ∆𝑈 ∙ 𝐼ОЗЗ

Arc channel heating samples

Arc length 4 mm, current 5.8 A

Arc length 16 mm, current 9 A

Finite elements calculations

Surface temperature along the cable

Damage region temperature vstime

Arc length 4 mm, current 5.8 A

Conclusions

Temperature field disturbance without thermical destructions ΔT= 50-300 K for typical phase earthing current 5 - 20 A

disturbance area length 1 m

the faults by phase earthing in the grids 6-35 kV can be detected by DTS systems