Use Of Symmetrical Components Research Articles

Use of Symmetrical Components in the Study of Electrical Disturbances in Distribution Systems with Charging Allocation for Electric Vehicles and Battery Banks

This paper presents a study of electric power distribution systems, which include battery banks and electric vehicle charging.Emphasis is placed to detect and distinguish voltage disturbances, conductor breaks, and other events that commonly occur in distribution systems. The research uses free license software ATPDraw™ to accurately model distribution systems and replicate voltage characteristics. The study investigates the ideal location of electric vehicle chargers, battery banks and electrical voltage meters in distribution systems. For this purpose, the General Algebraic Modeling System (GAMS) will be used, which provides high-level mathematical optimization capabilities to improve the observability of the system. Research will focus on possible mitigation to the problems these factors can cause in the power distribution system and explore strategies to minimize their negative effects. The discoveries will help improve the system performance, stability, and reliability of power distribution systems and support the integration of electric vehicles and energy storage.

Arcing Faults Location Methods for Power Transmission Lines

This paper presents three different fault location approaches: one-end Takagi algorithm, two-end algorithm considering natural fault loops and neural network. It is assumed that three-phase voltages and currents from both ends of the line measured asynchronously are the input signals of the fault locator. In addition to natural fault loop signals also the use of symmetrical components (positive and negative or incremental positive sequence components) for fault location were considered. Results of the evaluation study have been included, analyzed and discussed. The impact of filtration has also been considered. DOI: 10.12736/issn.2300-3022.2014111

Directional relays without voltage sensors for distribution networks with distributed generation: Use of symmetrical components

This paper presents two local algorithms using only currents measurements that could be used as a back-up protection (after the loss of the voltage sensors) in directional relays for distribution networks with distributed generation (DG), or as additional directional relay dispatched along the feeders. These algorithms are based on the symmetrical components (0-zero, 1-positive and 2-negative sequences) of the 3-phases currents. Due to the power flows generated by the DG the positive sequence current argument is unforeseeable, thus it is not possible to use only the positive sequence. Then, we first propose in this paper an algorithm using the I 2/ I 0 ratio to locate a phase-to-ground fault upstream or downstream the detector. The second algorithm measures the zero and positive sequence components of the fifth harmonic of the current and calculates the I 0_5/ I 1_5 ratio. The performances of these algorithms are analysed for several DG power, fault resistance, capacitive current and neutral grounding (resistive and compensative grounding). The fluctuations of the phasors measurements is also taken into account in the range ±5% for the modulus and ±5° for the argument. The present paper shows that these algorithms can be reliable in the major part of the studied cases.

A comprehensive interactive microcomputer capability for demonstrating AC machine operation

A software package is described for graphically and analytically demonstrating the steady-state behavior of polyphase machines under a variety of operating conditions. Implemented in the C language, the program employs sophisticated screen color graphics to show the slow-motion progression of the appropriate voltage or current waves, the loci of the resulting magnetic fields, and the movement of the machine rotor. It can be used to dynamically illustrate revolving-field concepts, the use of symmetrical components, and the effects of synchronous machine torque angle and induction machine slip. Screen movement can be frozen and significant numerical values displayed at any point during program use. The user may specify stator voltages or currents with any degree of unbalance. The neutral connection is arbitrary and can be altered during program execution. Input data may be specified or altered interactively. The program is completely menu-driven and interactive, and contains help commands and instructions which enable it to be used without additional documentation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Demonstration of AC machine behavior through interactive color graphics

A microcomputer program that graphically illustrates steady-state polyphase machine behavior under a variety of balanced and unbalanced operating conditions is described. Implemented in the C language, the interactive program employs sophisticated screen color graphics to show the slow-motion progression of the appropriate voltage or current waves, the loci of the resulting magnetic fields, and the movement of the machine rotor. It can be used to illustrate dynamically revolving-field concepts, the use of symmetrical components, and the operation of synchronous and induction machines under conditions of sustained electrical unbalance. The motivation for such a program, its operation, and its capabilities are described. >

The tensor equations of electrical machines

In the analysis of modern electrical machine systems there has been a trend towards the use of various components of the variables and parameters of the system, examples being the use of symmetrical components and direct- and quadrature-axis quantities. Such quantities may be considered to be different “reference frames” to which the various currents, fluxes, etc., are referred. Kron has shown that such transformations may be expressed in a general way when the equations of a network or machine are written in tensor form.Transformations may then be carried out to any one of a number of reference axes, which may be stationary or rotating with respect to the windings of the machine or network. In particular it has been found that in certain cases there are advantages in analysing machines with respect to axes rotating with the flux.The purpose of the present paper is to investigate the tensor form of the equations of electrical machines, to demonstrate the differences between tensor and non-tensor terms and to show how these terms are interpreted in application to simple cases. The equations of primitive machine are examined in both stationary and rotating axes and the equations of a 3-phase series impedance and a 3-phase induction-motor are derived in both systems of reference.

The tensor equations of electrical machines

In the analysis of modern electrical machine systems there has been a trend towards the use of various components of the variables and parameters of the system, examples being the use of symmetrical components and direct- and quadrature-axis quantities. Such quantities may be considered to be different “reference frames” to which the various currents, fluxes, etc., are referred. Kron has shown that such transformations may be expressed in a general way when the equations of a network or machine are written in tensor form.Transformations may then be carried out to any one of a number of reference axes, which may be stationary or rotating with respect to the windings of the machine or network. In particular it has been found that in certain cases there are advantages in analysing machines with respect to axes rotating with the flux.The purpose of the present paper is to investigate the tensor form of the equations of electrical machines, to demonstrate the differences between tensor and non-tensor terms and to show how these terms are interpreted in application to simple cases. The equations of primitive machine are examined in both stationary and rotating axes and the equations of a 3-phase series impedance and a 3-phase induction-motor are derived in both systems of reference.