Finite element computation of electric field and charge density ofa pulsed energized electrostatic precipitator

This paper numerically analyzes the governing equations in pulsed energized wire-duct electrostatic precipitators (WDEP). The electric field along its spatial distribution and the voltage-current characteristics are evaluated in the presence of dust. The finite element method (FEM) and a modified method of characteristics are used to solve the time-dependent Poisson's equation and to satisfy the current continuity condition, respectively. The two methods are repeated iteratively to obtain a self-consistent solution of the describing equations. The effect of pulse rate variation on the computed results is also investigated. Comparing the computed results with previously obtained experimental and calculated values tests the effectiveness of this approach. The agreement with experimental results is found to be satisfactor

"A Systematic Approach to Nuclear Microscopy of Water Trees for a Large Number of Field-aged HV Cable Samples"

In order to perform micro-PIXE measurements on water trees in underground HV cables when a large number of cable samples are involved, a sequence of tests has been devised to minimize time and effort for sample preparation, water tree detection and analysis. These tests include electrical diagnostic tests to predict the possible presence of water trees, optical microscopy on cable insulation to detect water trees in the samples screened by the electrical tests, scanning electron microscopy for detailed surface topography of water trees, and nuclear microscopy for elemental composition and distribution maps of water trees. Correlations among the results of the four types of measurements are discussed to evaluate the usefulness of the methodolog

Finite element analysis of corona in wire-duct electrostaticprecipitators

This paper is aimed at the analysis of corona power loss associated with wire duct electrostatic precipitators (WDEP). The finite element method (FEM) is used to solve the Poisson's equation and a modified method of characteristics is used to satisfy the current continuity condition. The two methods are repeated iteratively to get a self consistent solution of the describing equations. The effectiveness of this approach is tested by comparing the computed results with previously experimental and calculated values. The agreement with experimental results is found to be satisfactor

Finite element solution of monopolar corona as influenced by ionlife time

This paper presents an iterative finite element technique for the analysis of monopolar ionized field in transmission line conductor to plane configurations. One of the main underlying assumptions adopted in the literature, namely, the constant ion mobility, is waived in a simple way. The impact of waiving this assumption on the computed corona current and ground plane current density profile is investigated. A laboratory model was built to check the accuracy of the calculated corona current and the ground plane current density characteristics. It has been found that the present calculated corona current and the ground plane current density, which assumed variable ion mobility, agreed well with those measured experimentally for laboratory and full scale models and are less than those obtained when assuming constant ion mobilit

"A Systematic Approach to Nuclear Microscopy of Water Trees for a Large Number of Field-aged HV Cable Samples"

In order to perform micro-PIXE measurements on water trees in underground HV cables when a large number of cable samples are involved, a sequence of tests has been devised to minimize time and effort for sample preparation, water tree detection and analysis. These tests include electrical diagnostic tests to predict the possible presence of water trees, optical microscopy on cable insulation to detect water trees in the samples screened by the electrical tests, scanning electron microscopy for detailed surface topography of water trees, and nuclear microscopy for elemental composition and distribution maps of water trees. Correlations among the results of the four types of measurements are discussed to evaluate the usefulness of the methodolog

"Particle Swarm Based Design of Variable Structure Stabilizer for a Nonlinear Model of SMIB System"

In this paper, a particle swarm-(PSO) based variable structure stabilizer (VSC) is proposed for enhancing the dynamic stability of a nonlinear model of synchronous machine infinite busbar system (SMIB). Unlike the methods reported in the literature which involve either linearizing the model of synchronous machine around a suitable operation point or applying nonlinear transformation techniques before linear control theory is used in designing a fixed parameter PSS, the present method formulates the design of VSC as an optimization problem and utilized the PSO algorithm to provide a simple and systematic way of arriving at the optimal feedback gains and switching vector values of the stabilizer. When compared to previous methods, simulation results showed the effectiveness of the proposed stabilizer design

Corona power loss, electric field, and current density profiles in bundled horizontal and vertical bipolar conductors

In this paper, computation of the corona current and, hence, the corona power loss associated with bipolar high-voltage direct current (HVDC) conductors is presented using the finite-element method (FEM) and the method of characteristics (MOC). The former method is used to solve Poisson's equation while the latter is used to satisfy the current continuity condition. The ground-plane current density and electric field profiles associated with the HVDC conductors are also calculated as a prerequisite for the computation of the corona current. The effectiveness of the present method is demonstrated using HVDC full-scale and laboratory-model transmission lines. Horizontal and vertical bipolar configurations are tested with 2 and 4 bundles. Comparison between previously measured and computed profiles and present calculations shows satisfactory agreement with previous measured and calculated values

"A Tabu Search Approach for the Design of Variable Structure Load Frequency Controller Incorporating Model Nonlinearities"

This paper presents a new method of designing Variable Structure Controllers (VSC) applied to the Load Frequency Control (LFC) problem. The proposed method formulates the design of VSC as an optimization problem and utilizes Tabu Search Algorithm (TS) to find the optimal settings of the controller. The objective function used in the optimization process guarantees enhancement of the controller performance and reduces VSC chattering. The designed VSC is applied to LFC model that incorporates the nonlinearity of the Generation Rate Constraint (GRC). Furthermore, the complexity of the controller is reduced by using only the accessible states in designing the VSC. Comparison with other LFC methods reported in literature validates the significance of the proposed VSC design

" Design of Variable Structure Stabilizer for a Nonlinesr Mode of SMIB System: Particle Swarm Approach"

In this paper, a particle swarm-(PSO) based variable structure stabilizer (VSC) is proposed for enhancing the dynamic stability of a nonlinear model of synchronous machine infinite busbar system (SMIB). Unlike the methods reported in the literature which involve either linearizing the model of synchronous machine around a suitable operation point or applying nonlinear transformation techniques before linear control theory is used in designing a fixed parameter PSS, the present method formulates the design of VSC as an optimization problem and utilized the PSO algorithm to provide a simple and systematic way of arriving at the optimal feedback gains and switching vector values of the stabilizer. When compared to previous methods, simulation results showed the effectiveness of the proposed stabilizer design

Adaptive finite-element ballooning analysis of bipolar ionizedfields

This paper presents an adaptive finite-element iterative method for the analysis of the ionized field around bipolar high-voltage direct-current (HVDC) transmission line conductors without resort to Deutsch's assumption. A new iterative finite-element ballooning technique is used to solve Poisson's equation wherein the commonly used artificial boundary around the transmission line conductors is simulated at infinity. Unlike all attempts reported in the literature for the solution of ionized field, the constancy of the conductors' surface field at the corona onset value is directly implemented in the finite-element formulation. In order to investigate the effectiveness of the proposed method, a laboratory model was built. It has been found that the calculated V-I characteristics and the ground-plane current density agreed well with those measured experimentally. The simplicity in computer programming in addition to the low number of iterations required to achieve convergence characterize this method of analysi