S. Abdel-Sattar

Finite Element Solution of Monopolar Corona Equation

In this paper, the monopolar corona equation is solved using a modified finite element method (FEM) to give the corona current caused by overhea dc transmission lines without using the commonly-used Deutschs assumption The method is free from empiricism and entails implicitly a decrease of thsurface field intensity of the conductor with the applied voltage in the same manner as observed experimentally. This in itself represents an additional improvement for the analysis of ionized field where the approximation pertinent to the assumption of constant surface field intensity is mitigated. The calculated corona current as well as the current density at the ground plane agreed with those measured experimentally for a laboratory model.

Monopolar Corona on Bundle Conductors

In this paper, the monopolar corona equation is solved for bundle conductor using a modified iterative procedure to give the corona current contributed by each subconductor of the bundle. Some of the main underlying assumptions are waived in the present calculations. The variation of ion mobility with its life time as well as the change of corona onset voltage from point to point on each subgonductor ore taken into account for the first time. The calculated corona currents from each subconduotor are compared with those measured experimentally for a laboratory model.

Calculation of corona V-I characteristics of monopolar bundles using the charge simulation method

The charge simulation method is used to model the V-I characteristics of corona from monopolar bundled transmission lines without resort to W. Deutschs (1933) assumption. The proposed method of analysis predicts V-I characteristics of corona from conductor bundles, irrespective of the number of subcontractors per bundle. Compared with the iterative method based on Deutschs assumption, the proposed method predicts V-I characteristics closer to those measured experimentally. The accuracy of the method is at the expense of the computer time required for the calculation procedure, that in turn being longer than the time required by the iterative method. >

Monopolar Corona on Bundle Wires as Influenced by Wind

The measured corona current contributed by each subwire in various laboratory-size bundle models and the total corona current change with wind over a wide range of applied voltages are described. The lateral spacial distribution of the time-average value of windblown corona current over the ground plate is measured for different applied voltages and different bundle geometries. The obtained results are compared to previous findings and to theories of corona discharge.

Positive Corona in Point-Plane Gaps as Influenced by Wind

In this paper, the effect of wind on positive corona behavior up to breakdown is studied for point-plane gaps when the wind is flowing axially (against or parallel to the direction of ion convection from the point to the plane). The repetition rate of streamer pulses and its randomness as influenced by wind has been determined for different applied voltages. The spatial distribution of the current density over the ground plane has been examined for different applied voltages in still air and with wind blowing in the axial and transverse directions. The time-averaged value of wind-blown corona current as a function of the applied voltage was also determined. The results obtained are correlated with previous findings and with the theories of corona discharges.

Numerical Method to Calculate Corona Profiles at Ground level and underneath Monopolar Lines as Influenced by wind

In this paper, the monopolar corona equations are solved numerically in flowing air for HVDC transmission lines with bundle conductors. The lateral distributions of the corona current density and field intensity over the ground surface and underneath monopolar HVDC models are calculated and compared with those measured experimentally.

Corona Current and Field Profile Underneath Vertical Bipolar HVDC Lines with Bundle Conductors

For the cases of monopolar and horizontal bipolar coronas, the corona equations are solved for vertical bipolar geometry without restrictions with regard to the number of subconductors. The variation of ion mobility with lifetime, as well as the change of corona onset voltage from point to point around each subconductor, are taken into account. The lateral distribution of the field intensity and current density calculated and compared with those measured experimentally. These profiles also are compared with those for a horizontal bipolar test line. The effect of applied voltage, number of subconductors and the surface factor is studied.

Symmetrical Component Analysis of Multi-Pulse Converter Systems

This article describes a new method for dynamic simulation of multi-converter systems. This simulation is based on symmetrical components in time domain analysis and general representation of converter transformers to meet Y/Δ, Y/Y, and Y/Z connections. The simulation is suitable for harmonic analysis of balanced and unbalanced AC voltages. The computed currents and voltages agreed reasonably with those measured and reported in the literature for the characteristic and non-characteristic harmonics.

Saturated corona profiles at ground surfaces and underneath HVDC lines

Saturated profiles of the field intensity, current density and charge density at the ground surface and underneath monopolar HVDC transmission lines are calculated by using simple expressions. These expressions give the relation between the saturated values and the length of the field lines emanating from or terminating at the energized conductor. The calculated values are compared with those previously calculated and measured experimentally. Both absolute and normalized saturated corona profiles at the ground surface and underneath HVDC monopolar transmission lines are calculated using simple expressions. Relations between the saturated values at any position on the ground surface and the length of the field line emanating from or terminating at the conductor are given. These relationships are used for both outdoor and indoor models. >

DC corona discharge on monopolar bundle wires

The solution of monopolar corona equation already reported in literature is extended for bundle conductors using a modified iterative procedure to estimate the corona current contributed by each subconductor of the bundle. The solution is based on underlying assumptions, some of which are waived in the present calculations. The variation of ion mobility with its lifetime as well as the change of the corona onset voltage from point to point on each subconductor are taken into account for the first time. The calculated corona currents from each subconductor are compared with those measured experimentally for a laboratory model.