Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With coupling means
Reexamination Certificate
1999-06-14
2004-03-30
Le, N. (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With coupling means
C324S107000, C340S870250, C702S062000
Reexamination Certificate
active
06714000
ABSTRACT:
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for the measuring of power and current flowing through transmission lines, and of the power generation or consumption of a facility.
BACKGROUND OF THE INVENTION
As the traditional monopolies of electric utilities have been relaxed in the United States, there has developed a growing market in wholesale electric energy. Utilities, independent power producers, and power marketers are some of the participants in this volatile market. Among other variables, such as time of day and year, and temperature, electricity pricing in a given region is dependent on the operational status of the electric generation and use facilities in that region, and the transmission capacity of critical transmission paths.
Participants in the electric power markets, accordingly, would find real-time information on the operational status of important generation, use, and transmission facilities in a region to be useful in developing trading strategies and responses to power system events. Likewise, relaxation of the monopoly status of traditional utilities has resulted in increased competition for customers amongst suppliers of electric energy. Information on the electric power use of potential customers would be useful to those involved in bidding for electricity supply contracts. It would be further advantageous to determine information on the supply and demand of electric energy without having to directly connect to the transmission and distribution lines conducting electric energy.
It is, therefore, an object of the present invention to provide a methodology whereby real-time information on transmission line power flow, generation facility power output, substation power input and output, and facility power use may be obtained remotely and transmitted to an end-user of such information. It is also an object of this invention to provide an apparatus capable of accomplishing this task. It is a further object of this invention to collect and provide this information accurately, regardless of changing environmental conditions, over the long-term, and with a minimum of human involvement. Furthermore, it is an object of this invention to provide this information to an end-user in such a form as to permit the end-user to act in a logical and timely fashion to real-time events on the power system.
SUMMARY OF THE INVENTION
Towards the accomplishment of these objects, disclosed is a method for determining in real-time the net electric power and current either generated or consumed by a facility or substation, and the electric power and current transported by an electric transmission line. This is accomplished, in part, through the use of one or more apparatuses for monitoring the magnitude and direction of electric power or current flow in a single electric current carrying conductor or in multiple current carrying conductors operating in a poly-phase arrangement. The present invention thus relates generally to a method and apparatus for the long-term, real-time, remote monitoring of the electric power and current flow to, from, or in a monitored facility.
For the purpose of the following discussion, the terms “transmission line” and “electrical line” will generally refer to a set of at least three conductors operated in a poly-phase arrangement for the purpose of transmitting electric energy. Each of the three conductors comprising the transmission line is energized with a sinusoidal voltage 120 degrees out of phase with the other two conductors comprising the transmission line. “Bundled” conductors, which consist of multiple wires in close proximity to one another that are operated electrically in parallel, will be referred to and treated as a single conductor.
Current and power monitoring according to the present invention may be accomplished by placing one or more of the apparatuses described herein in proximity to each of the electrical transmission lines that provide service to a monitored facility. Generally, it is desired that an apparatus be located within approximately 200 feet of the monitored line, though the actual location of the apparatus is dependent on terrain, line geometry, and other factors unique to the particular line. It is to be understood that the present invention may be used to measure characteristics from single or multiple lines, instead of a facility.
Each individual apparatus transduces magnetic fields emanating from the monitored power line and determines the phase relationship to another signal that is synchronized to power system frequency. This signal, in an exemplary embodiment, may be the electric field emanating from the monitored line. It may also be a measure of the voltage derived from some electrical connection to the power system such as that obtained from an electrical wall outlet. By this synchronization, a measure of the direction of current flow in the line is determined. Because any given distribution or transmission line is operated at near uniform voltage, a measure of the current flow in a line is also a measure of the complex power flow in the line. The power flow can be divided into its real and reactive components through use of the phase angle relationship between the monitored magnetic fields and the synchronized signal.
Standard transmission or distribution lines typically consist of at least three current carrying conductors. Multiple monitoring devices devoted to each line may give increased sensitivity in determining the current flow in the individual conductors using methods such as that described in U.S. Pat. No. 5,438,256, the disclosure of which is hereby incorporated by reference. However, because the method of operation of most transmission lines is predictable, it is possible to monitor a single poly-phase line with a single apparatus, as disclosed herein. Furthermore, multiple poly-phase circuits that are carried on the same transmission structure may be individually monitored using the apparatus and methods disclosed herein.
In an exemplary embodiment of the present invention, magnetic fields may be transduced either through the use of coil probes or Hall effect sensors. Electric fields may be transduced through the use of a free-body meter, or a ground-reference type meter, as described in IEEE Standard 644-1994.
After transduction, signals representing the electric and magnetic field strength may be magnified and filtered. The magnitudes and relative phase angles of these signals are then converted to digital signals, evaluated, and, in an exemplary embodiment, stored by use of a microcontroller or microprocessor, at least one analog to digital (A/D) converter, and digital memory. The microprocessor may be programmed to analyze and record the data received through the A/D converter.
Included in an exemplary embodiment of the apparatus according to the present invention is a device that permits communication between the remote apparatus and a central computing facility. This communication device may comprise, for example, a cellular telephone and modem connected to the microcontroller. Similarly, a radio-frequency, or microwave connection may be made between the apparatus and the central computing facility. Satellite communication between the apparatus and the computing facility is also realizable. Algorithms in the microcontroller determine when and if the apparatus should communicate with the central computing facility, or provide some other form of communication, such as an event-notification alarm, directly to an end-user.
Where environmental concerns exist, the apparatus may include an enclosure that protects the components of the apparatus from the elements. This enclosure may be constructed of material
Genscape, Inc.
Kerveros James
Le N.
Nagle, Jr. David W.
Stites & Harbison PLLC
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