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العنوان
Analytical study of medium voltage cables problems /
المؤلف
Abd El-Aziz, Mohamed Sabri Hassan.
هيئة الاعداد
باحث / محمد صبرى حسن عبدالعزيز
مشرف / مجدى محمد السعداوى
مشرف / محمد العدوى خليل العدوى
مناقش / صبحى سرى دسوقى
مناقش / إبراهيم عبدالغفار بدران
الموضوع
Electric cables. Dielectrics.
تاريخ النشر
2018.
عدد الصفحات
143 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الهندسة الكهربائية والالكترونية
تاريخ الإجازة
01/09/2018
مكان الإجازة
جامعة المنصورة - كلية الهندسة - Engineering
الفهرس
Only 14 pages are availabe for public view

from 143

from 143

Abstract

Underground distribution cable systems represent a large part of the distribution company’s physical capital. The MV network failure has a huge influence on interruption which customers suffer, because the biggest part of the interruptions is a result of medium voltage network faults. Faults have a very bad effect on both customers and distribution companies. Accurate fault location for the MV cable network is of vital importance in restoring power services and reducing outage time as much as possible. Reliability and quality of underground cables network are affected by the occurrence of faults. Analyzing the causes of MV power cable network faults is necessary to improve the efficiency of the MV distribution network and consequently increase the reliability service continuity of the distribution system. This thesis presents an analytical study of medium voltage cables problems. The objective of the thesis is to investigate, analyze and discuss these problems. For this purpose, the thesis explores detailed knowledge about the basic concepts of MV power cable systems and causes of their deteriorations. A Medium Voltage (MV) power cable system consists of cables themselves and their accessories. Cables accessories are used to connect MV cable networks and they are categorized as joints and terminations. Joints connect cables together whereas terminations connect the end of a cable to another element of the network. The reliability of MV power cable systems depends on the efficiency of all elements separately. But, cable joints are one of the major components of MV cable systems that can define system reliability. It is well known that the electric stress distribution is the primary factor in the initiation of cable insulation failure process. Studying the electric field and potential distribution inside the cables and their accessories allows the identification of local field enhancement which may leads to local breakdown of the insulation. The simulation of the electric field and potential distribution represents a simple tool to determine field distribution inside the power cable. This simulation helps in designing a model of cable to improve the electric field distribution and to reduce the harmful effects to the system over the long term of operation. The thesis investigates the main types of faults in MV cable network and the practical procedures of faults diagnosis and location in these networks. A brief discussion about practical applications of fault detection in different zones of NDEDC is presented. The finite element simulation technique is used to evaluate the electric field inside both the single and three phase power cables. The investigation is implemented through modeling a medium voltage cable using open source Finite Element Method Magnetics (FEMM) software with octave to investigate several areas of importance, not solvable using analytical techniques such as void content and location in the insulation material. Due to the great importance cables accessories (joints and terminations) and the fact that cable joints are a main source of defects that may lead to cable system failures, the electric field stress and potential distribution in joints are investigated. The computation of the electric field and potential is implemented through modeling a MV cable joint using octaveFEMM numerical simulation program. The effects of different insulation materials, void size and void location on the electric field magnitude within the void in the cable joint are investigated.