The author provides a comprehensive review of the basic charge simulation method and its various modified versions reported in the literature. Applications of the charge simulation method, alone as well as in combination with other methods, are considered. Different aspects of this method are critically examined and its potentials and limitations are identified. Possible areas of future research are outlined in order to improve the overall effectiveness of computer-aided analysis and design of high-voltage insulation devices by using the charge simulation method. >

A review of the charge simulation method and its applications

In this paper, a generalized leader inception model is proposed. It is based on an iterative geometrical analysis of the background potential distribution of an earthed structure to simulate the first meters of propagation of an upward connecting leader. By assuming a static field approach, the leader stabilization fields and the striking distances were computed for a lightning rod and for a building. The obtained results were compared with the existing leader inception criteria. Furthermore, in order to validate the model, the leader inception condition was computed for a triggered lightning experiment. Excellent agreement with the experimental results was obtained. The present model has several advantages in comparison with the existing leader inception criteria. One of them is related to the fact that the proposed model can be used to analyze the effect of the space charge on the upward leader inception.

A simplified physical model to determine the lightning upward connecting leader inception

Calculation of the electric field and potential distribution is extensively performed in the design and development of nonceramic insulators for high voltage transmission applications. This paper applies a two-dimensional (2-D) and a three-dimensional (3-D) electric field analysis program to calculate the field distribution of the insulators under clean and dry conditions. A three-phase 345 kV transmission tower with nonceramic suspension insulators (two I-strings and one V-string) was analyzed with each phase as an individual case. The effects of conductors, tower configurations and grading devices on the electric field and potential distribution along the insulators were investigated. The calculation results show that the factors investigated have different levels of effects on the distribution.

Calculation of electric field and potential distribution along nonceramic insulators considering the effects of conductors and transmission towers

During the past few years the ac capacitor industry has seen almost a complete change in dielectrics, electrodes, and impregnants. The dielectric has changed from paper to all poly-propylene film, the electrode from plain foil to either metallized film, metallized paper, or embossed foil, and the fluids have changed from polychlorinated biphenyls (PCB) to those based on hydrocarbon or phthalate ester chemistries. This paper discusses the rational behind this changing technology, the improved performance aspects of these new designs, and some of the degradation mechanisms that have accompanied these changes.

A Changing Capacitor Technology - Failure Mechanisms and Design Innovations

A modified charge simulation method for calculating the electric potential and field distribution along AC HV outdoor insulators is presented. The salient feature of this method is the significantly smaller number of unknowns and the corresponding reduction in computational complexity when compared to earlier charge simulation methods. Non-ceramic and ceramic suspension insulators of voltage ratings ranging from 115 to 500 kV, and non-ceramic line posts (115 and 230 kV) have been modeled under clean and dry surface conditions. Good agreement is obtained between the present calculations and measured data, calculated values using other numerical techniques and observations from service experience, which demonstrates the practical viability of the technique. >

Electric potential and field computation along AC HV insulators

A new approach for the computation of electric fields is described, based on the application of optimization techniques to the charge simulation method. The charge simulation technique is briefly considered and the optimized version is formulated. The potential distribution of the rod-plane configuration is solved as a sample problem for comparative purposes, and consideration is given to the solution of field distributions with non-axial symmetry. The new optimized approach proves to be more efficient, minimizing the time required to set up and implement a solution of this kind.

P. H. Alexander

Papers

An Optimized Charge Simulation Method for the Calculation of High Voltage Fields