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Authors: Carl J. Spezia, Constantine I Hatziadoniu
© 2004, 2002, 1997, 1993 PTC. All rights reserved.
The documents in this book carry out common design calculations from electrical power systems engineering. These applications use Mathcad's complex arithmetic, matrix operators, equation solving power, and plotting capabilities to provide a reference source of Mathcad methods and formulas for students and practicing power engineers. This book includes applications in the following areas:
- Power Distribution Problems
- Protection Issues
- Electrical Transient Phenomena
Worksheets marked with 
use PTC Mathcad premium features, otherwise they are Express compatible. All worksheets created in PTC Mathcad Prime 3.0.
| Chapter | Worksheet | Description |
|---|---|---|
| 1. Power Distribution | Per Unit System | A single-phase model represents balanced three-phase systems in most power systems calculations. The load flow and short circuit models reduce the three-phase model to a single-phase representation of the system when balanced operation is assumed. |
| Voltage Drop Calculations | In this section, a method is presented for the calculation of the voltage profile and power losses with application examples for both open and closed lines. This method may be used to improve the performance of a line by investigating the application of shunt capacitors and other schemes for mitigating the adverse effects of voltage drops. | |
| Load Flow Calculations - Theory | The approach used here for solving the load flow is based on the Newton-Raphson iterative method. The required input to the problem is the generated and load power at each bus and the voltage magnitude on generating buses. This information is acquired from load data and the normal system operating conditions. The solution provides the voltage magnitude and phase angle at all buses and the power flows and losses of the transmission lines. | |
| Load Flow Calculations - Application | ||
| Least-Cost Power Transformer Sizing - Efficiency | This section gives a method for computing the total cost to own a power transformer that includes all the important economic and technical factors. | |
| Least-Cost Power Transformer Sizing - Cost Estimation | ||
| Power System Harmonic Analysis - Introduction | This section lists possible harmonic sources, their frequency content, and a method of identifying harmonic interaction between a source and a system. | |
| Power System Harmonic Analysis - Harmonic Interactions | ||
| Power Line Parameters - Introduction | This section provide methods for computing the resistance, inductance, and capacitance for transmission and distribution lines. The procedures make use of tabulated values for common conductor sizes used in industry, and are included in a table at the end of this section. | |
| Power Line Parameters - Sequence Impedance of Lines | ||
| 2. Power System Protection | Power System Faults - Introduction | This section provides the calculation of the symmetrical subtransient current and the system voltage due to system faults including: (a) single-line-to-ground, (b) double-line, (c) double-line-to-ground (asymmetrical faults) and (d) three-phase (symmetrical faults). The method of calculation is based on the sequence components of the system bus-impedance matrix. |
| Power System Faults - Application | ||
| Mid-Line Fault Calculations | Most faults occur at a point on a line some distance from the substation bus. The current seen by a line protection system during a mid-line fault is typically much less than that for a bus fault, and varies in magnitude depending on the position of the fault relative to the end-point buses. | |
| Out-of-Step Protection - Theory | This section provides methods for simulating power swings and the corresponding impedance seen by the impedance relay. Graphic comparison between the relay characteristic and the transient response of the system can help in the application of blinders, the setting of time delays and other auxiliary logic for obtaining the proper coordination. | |
| Out-of-Step Protection - Application | ||
| Introduction Motor Start-up Protection | The protection coordination method provided in this section derives the transient trajectories of the motor in the time domain for overcurrent relay schemes and in the complex impedance domain for impedance relay schemes, and compares these trajectories with the corresponding characteristics of the protection scheme. From this comparison, the required relay settings can be obtained. | |
| DC Motor Protection - Modeling | This application outlines a method for simulating the transient response of a separately excited dc motor with various load torque characteristics. | |
| DC Motor Protection - Simulation | ||
| 3. Power System Electrical Transients | Review of System Transients - Introduction | This section reviews electrical transients in power systems with applications for common situations and protection practices. |
| Review of System Transients - Transient Overvoltages | ||
| Transformer Energization - Theory | Transformer behavior under varying line conditions is described by the nonlinear characteristic of its magnetic core. This characteristic is a relation between the magnetic core flux and the transformer magnetizing current. Principal features of this relation are saturation and hysteresis. | |
| Transformer Energization - Modeling | ||
| Transformer Energization - Compensation | ||
| Application of Surge Arresters | This section describes the main characteristics of surge arresters and provides a method for the calculation of arrester energy and system voltage in abnormal system conditions. | |
| 4. Front and Back Matters | Front and Back Matters | Includes sections like "About this E-Book"; summary of chapter 1, 2 and 3; Cover; Index, Toc,... |
