The objective of this document is to report results in the detection and characterization of special behavior
in large electric power systems. Such behavior is usually dynamic in nature, but not always. This is also
true for the underlying sources of special behavior. At the device level, a source of special behavior
might be an automatic control system, a dynamic load, or even a manual control system that is operated
according to some sharply defined policy. Other possible sources include passive system conditions, such
as the state of a switched device or the amount of power carried on some critical line.
Detection and characterization are based upon “signature information” that is extracted from the behavior
observed. Characterization elements include the signature information itself, the nature of the behavior
and its likely causes, and the associated implications for the system or for the public at large. With
sufficient data and processing, this characterization may directly identify a particular condition or device
at a specific location. Such conclusive results cannot always be done from just one observation, however.
Information environments that are very sparse may require multiple observations, comparative model
studies, and even direct testing of the system.
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Wednesday, August 6, 2008
Tuesday, August 5, 2008
How to Size a Grid-Connected Solar Electric System
The easiest way to size your solar electric system is to have a vendor come to your home and perform a site analysis and load assessment. Solar electric vendors have the experience and tools necessary to gather the data needed for the calculations. Most vendors will supply predesigned package systems that range from one kilowatt (kW) for a small energy-efficient home up to 2.5 kW for a large home.
However, if you want to determine the size of the system yourself, the following two-step process will help you to estimate the number of solar panels (sometimes referred to as modules) required, the size of your inverter, and if desired, the size of batteries to buy for backup power. Remember, the goal of the sizing process is to yield a rough estimate of the number of kilowatts your solar electric system should generate. In short, you want to size your solar electric system to meet no more than your whole load on the sunniest day of the year, and rely on some grid power during winter or cloudy days.
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However, if you want to determine the size of the system yourself, the following two-step process will help you to estimate the number of solar panels (sometimes referred to as modules) required, the size of your inverter, and if desired, the size of batteries to buy for backup power. Remember, the goal of the sizing process is to yield a rough estimate of the number of kilowatts your solar electric system should generate. In short, you want to size your solar electric system to meet no more than your whole load on the sunniest day of the year, and rely on some grid power during winter or cloudy days.
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Monday, August 4, 2008
Teaching Electric Circuit Theory with the Help of Tutorial Software
Electric Circuit Theory (ECT) has been a fundamental component of the teaching of electrical engineering since the dawn of university electrical engineering studies at the beginning of this century. In reflection of developments in the USA it was later introduced as an independent subject in most faculties of electrical engineering. Highly developed and deeply considered methods of pedagogical presentation, including excellent textbooks, examples and other teaching aids, have emerged in the long-term development of this field of science.
There is clearly an important role for contemporary computer science in the teaching of technical disciplines, including ECT, but this does not simply suggest an improvement of hitherto used teaching methods: in many instances it is necessary to rebuild these methods from the ground up. In fact it could be observed that the existence of a well developed classic pedagogical system in the teaching of ECT, one that has proven with time to be effective, and the necessity to undergo a revolutionary conversion of this system in order to adopt a modern computer-based teaching technology might be factors in the fairly slow introduction of computer-aided teaching in this discipline. The same situation can be found in other theoretical disciplines of electrical engineering.
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There is clearly an important role for contemporary computer science in the teaching of technical disciplines, including ECT, but this does not simply suggest an improvement of hitherto used teaching methods: in many instances it is necessary to rebuild these methods from the ground up. In fact it could be observed that the existence of a well developed classic pedagogical system in the teaching of ECT, one that has proven with time to be effective, and the necessity to undergo a revolutionary conversion of this system in order to adopt a modern computer-based teaching technology might be factors in the fairly slow introduction of computer-aided teaching in this discipline. The same situation can be found in other theoretical disciplines of electrical engineering.
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Sunday, August 3, 2008
Analysis of the Electrical Engineering Problems Using Computer Tools
The theory of electrical circuits represents one of most important parts of the Electrical Engineering education. The main aims of this course are to obtain the knowledge of circuit analysis and synthesis and to see the experience of actual behavior of typical circuits. This purpose needs using of powerful software mathematical tools.
The MATLAB is numeric computation software for package engineering and scientific calculations. The main reasons for wide spread using of MATLAB are following [1]: easy to learn and use; powerful, flexible and extensible; accurate, robust and fast; widely used in engineering and science; backed by a professional software company. This paper presents an approach according to teaching of circuit analysis topics using specially designed exercises that can be done on the base of MATLAB running on personal computers.
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The MATLAB is numeric computation software for package engineering and scientific calculations. The main reasons for wide spread using of MATLAB are following [1]: easy to learn and use; powerful, flexible and extensible; accurate, robust and fast; widely used in engineering and science; backed by a professional software company. This paper presents an approach according to teaching of circuit analysis topics using specially designed exercises that can be done on the base of MATLAB running on personal computers.
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Electric Fields Tutorial
Welcome to the Electric Fields Tutorial program. The program reviews a set of concepts that are important in understanding electric fields.
You will review
how to use a vector to represent the electric field
- how the force on a charged particle is related to the electric field.
- how to find the electric field at a point
You should already know
- what an electric charge is.
- the units used to measure electric charge.
- that electric fields exist around charged objects.
- the units used to measure electric field
You will need a calculator, paper, and a pencil or pen.
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You will review
how to use a vector to represent the electric field
- how the force on a charged particle is related to the electric field.
- how to find the electric field at a point
You should already know
- what an electric charge is.
- the units used to measure electric charge.
- that electric fields exist around charged objects.
- the units used to measure electric field
You will need a calculator, paper, and a pencil or pen.
Download
Cyber Security of Electric Power Infrastructure
Critical infrastructures are defined as systems whose incapacity or destruction would have a debilitating impact on the national security and the economic and social welfare of a nation. It includes such infrastructures like telecommunications, electric power, gas and oil, banking and finance, transportation, water supply, and government and emergency services.
Towards the end of the 20 th century electric power infrastructure emerged as one of the most critical infrastructure in the sense that all other critical and vital infrastructures depend on reliable electricity supply. It is also considered as one of the most vulnerable to physical and cyber attack. Present-day electric power systems, which are physical part of electric power infrastructure, are complex and technologically advanced systems. Assuring cyber security of these systems it is difficult interdisciplinary task. The task is difficult because of great complexity of these systems. But to some extend it is also difficult because risk analysis in these systems is based on concepts that are normally not known in others sectors of industry and in information technology and can be difficult to understand for specialists from these fields who are not familiar with electric power systems.
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Towards the end of the 20 th century electric power infrastructure emerged as one of the most critical infrastructure in the sense that all other critical and vital infrastructures depend on reliable electricity supply. It is also considered as one of the most vulnerable to physical and cyber attack. Present-day electric power systems, which are physical part of electric power infrastructure, are complex and technologically advanced systems. Assuring cyber security of these systems it is difficult interdisciplinary task. The task is difficult because of great complexity of these systems. But to some extend it is also difficult because risk analysis in these systems is based on concepts that are normally not known in others sectors of industry and in information technology and can be difficult to understand for specialists from these fields who are not familiar with electric power systems.
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Electric Tutorial
This tutorial will run through the design and simulation of a ‘plain vanilla’ positive edge triggered D flip-flop. Electric allows the design to be done and linked together through what are called facets. These facets are each different hierarchical levels of the design (i.e. Layout, schematic, VHDL, and so on). The design of this flip-flop will be covered in the transistor, schematic, VHDL, and layout levels. The purpose of this tutorial is to cover those topics that are not covered sufficiently in the provided User’s Manual. It is assumed that the student knows how to create a library and facets of that library.
Creating a Gate-Level Schematic Using Provided Logic Gates: We first created a digital schematic facet in the D Flip-Flop library using the digital gates provided in Electric. The schematic we used can be found in any basic logic design textbook. Placing a node (such as an “or” gate) on the schematic is done by the traditional click-and-place method (see manual).
Electric provides standard variable-input logic gates (and, or, xor, buffer). To negate inputs/outputs, click on the arc that connects to those nodes and select Arcs Negated. Simulation of Gate-Level Schematic: The simulation of the circuit can be done by selecting, Tools Simulation Simulate in the pull down menu. Please note that by simulating the circuit, the VHDL facet will automatically be created. A new window will open with a waveform for each port. To force the inputs, select the net by clicking on the name to the left. If the signal is a clock simple...
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Creating a Gate-Level Schematic Using Provided Logic Gates: We first created a digital schematic facet in the D Flip-Flop library using the digital gates provided in Electric. The schematic we used can be found in any basic logic design textbook. Placing a node (such as an “or” gate) on the schematic is done by the traditional click-and-place method (see manual).
Electric provides standard variable-input logic gates (and, or, xor, buffer). To negate inputs/outputs, click on the arc that connects to those nodes and select Arcs Negated. Simulation of Gate-Level Schematic: The simulation of the circuit can be done by selecting, Tools Simulation Simulate in the pull down menu. Please note that by simulating the circuit, the VHDL facet will automatically be created. A new window will open with a waveform for each port. To force the inputs, select the net by clicking on the name to the left. If the signal is a clock simple...
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