A.Y. Chikhani

Power quality detection and classification using wavelet-multiresolution signal decomposition

The wavelet transform is introduced as a powerful tool for monitoring power quality problems generated due to the dynamic performance of industrial plants. The paper presents a multiresolution signal decomposition technique as an efficient method in analyzing transient events. The multiresolution signal decomposition has the ability to detect and localize transient events and furthermore classify different power quality disturbances. It can also be used to distinguish among similar disturbances.

Classification of capacitor allocation techniques

The problem of capacitor allocation for loss reduction in electric distribution systems has been extensively researched over the past several decades. This paper describes the evolution of the research and provides an evaluation of the practicality and accuracy of the capacitor placement algorithms in the literature. The intent of this paper is not to provide a complete survey of all the literature in capacitor allocation, but to provide researchers and utility engineers further insight into the choices of available capacitor allocation techniques and their respective merits and shortcomings. Furthermore, this paper serves as a useful and practical guideline to assist in the implementation of an appropriate capacitor allocation technique.

Capacitor allocation by approximate reasoning: fuzzy capacitor placement

The problem of capacitor allocation in electric distribution systems involves maximizing energy and peak power (demand) loss reductions by means of capacitor installations. This paper presents a novel approach using approximate reasoning to determine suitable candidate nodes in a distribution system for capacitor placement. Voltages and power loss reduction indices of distribution system nodes are modeled by fuzzy membership functions. A fuzzy expert system (FES) containing a set of heuristic rules is then used to determine the capacitor placement suitability of each node in the distribution system. Capacitors are placed on the nodes with the highest suitability. Simulation results show the advantages of this approach over previous capacitor placement algorithms.

Adequacy assessment of distributed generation systems using Monte Carlo Simulation

This paper presents a Monte Carlo-based method for the adequacy assessment of distributed generation systems. The state duration sampling approach is employed in this paper to model the operating histories of the installed distributed generators. A general procedure to assess the ability of the system power capacity to meet the total demand is presented and implemented in a typical case study where several distributed generation units are running in parallel within a sample distribution system and the system margins and the average amount of unsupplied loads are estimated using Monte Carlo simulation. The results obtained are presented and a new perspective to the power management of distribution systems is discussed.

A survey of the state of the art in distribution system reconfiguration for system loss reduction

Abstract A survey of publications in the area of distribution system reconfiguration for loss reduction is presented. The prevailing world social, political, and economic climates dictate that every effort be made to render the generation, transmission, and distribution of electricity as efficient as possible. Through the use of existing tie and sectionalizing switches, reconfiguration of the distribution system represents an attractive method of loss reduction as it can be implemented at minimal cost to the utility. Techniques of reconfiguration, ranging from the fundamental work of Merlin and Bach to the current state of the art, are outlined.

A simplified network approach to the VAr control problem for radial distribution systems

A simplified network approach to the VAr (volt-ampere reactive) control problem in a distribution system with lateral branches is presented. According to this method, the power capacitors are assumed to be located optimally at the feeder branches. The optimal compensation levels (capacitor size) are represented by dependent current sources located at the branch connected buses. The solution of the equivalent circuit for the distribution system yields the values of the voltage at any bus. The actual compensation level is then determined by substituting the bus voltage in the dependent current source formula. The method can be used as an online controller and in the planning stage. It can be easily adapted in an expert system configuration. >

Pattern recognition applications for power system disturbance classification

This paper presents an automated on-line disturbance classification technique. This technique is based on wavelet multiresolution analysis and pattem recognition techniques. The wavelet-multiresolution transform is introduced as a powerful tool for feature extraction in order to classify different disturbances. Minimum Euclidean distance, k-nearest neighbor, and neural network classifiers are used to evaluate the efficiency of the extracted features.

Application of multiresolution signal decomposition for monitoring short-duration variations in distribution systems

The multiresolution signal decomposition (MRA) technique is introduced as a powerful tool for detecting, classifying and quantifying the short duration variations in an electrical distribution system. Using the proposed technique, one will have the ability to measure the magnitude and duration of the signal during SDV events. Furthermore, the total harmonic distortion and the DC offset can also be measured. The information gained at different resolution levels and the measured values by the proposed technique can be used to distinguish among similar power quality phenomena and may help in finding the source of disturbance.

Distribution system reconfiguration for loss reduction: an algorithm based on network partitioning theory

The algorithm proposed in this paper provides the facility to achieve on-line distribution system reconfiguration for loss reduction. Based on partitioning the distribution network into groups of load busses, such that the line section losses between the groups of nodes are minimized, the proposed method overcomes the size restrictions imposed by previously described reconfiguration techniques. By dividing the distribution network into groups of busses, the combinatorial nature of the reconfiguration problem is overcome, while simultaneously minimizing losses. Computer simulations, of the proposed method, demonstrate the numerous benefits that are offered by the proposed reconfiguration algorithm.

Control of Reactive Power in Distribution Systems with an End-Load and Varying Load Condition

The flow of the reactive power in utility systems produces losses which utility engineers attempt to keep at a minimum level by the installation of capacitor banks. Previous work focussed on obtaining the optimal conditions for a fixed load level. The present paper deals with the conditions of fixed load, growth in the load and the presence of end-load in the feeder. A mathematical analysis of shunt capacitor application for the reductions of peak power loss and energy loss for a uniform feeder with an end-load condition is presented. Generalized equations for calculating the reductions of peak power and energy losses in a feeder are derived. The optimum location and the rating of the capacitor banks on feeders with uniformly distributed loads and end-load injection are developed. A method to assess the economical effectiveness of whether or not to install capacitor banks in a condition of load growth is also given. The method is applied to a test case of a practical system.