Software for Calculating the Non-Uniform Electric Field Causing Electrical Tree in Underground Cables

In this paper new software is introduced to calculate the non-uniform electric field resulting from a protrusion of the earthing shield for underground cables. The problem is simulated by hyperbolic needle-to-plane electrodes which produce a very high non-uniform electric field causing the growth of electrical tree. The calculation of the electric field is achieved by charge simulation method combined by genetic algorithms for optimum location and values of the charges over the needle electrode. The charge over the needle electrode is simulated by a set of ring charges. The calculations are for different types of the dielectric materials of underground cables (PVC and XLPE). This software introduce an easy, economic and safety method to calculate the electrostatic field for underground cable. Also it presents a new method for predicting if this field will cause tree or not and then the program can classify that cable.