SHORT CIRCUIT PROGRAM
Traditionally, short circuit studies are completed for two reasons: to determine the size of new equipment or to determine relay settings for the power system. System protection engineers are also analyzing actual fault conditions to check for accurate and coordinated relay operations. Operations personnel may want an occasional study to determine whether certain network configurations might result in fault currents that exceed equipment ratings.
Short Circuit Program Features
The TRANSMISSION 2000® Short Circuit (SC) program was specifically designed to improve upon and replace traditional short circuit programs. New developments in modeling techniques and solution algorithms were combined to produce a short circuit program with analytical capabilities far beyond those found in other fault analysis programs, mainframe or micro. While considerable effort was devoted to the technical features, just as much care was given to the user-program interface to ensure that the program is easy to use and understand. Among the SC features are:
- Interactive User Interface - A user interface that is easy for the novice user without requiring the kind of excessive structure that impedes experienced users. Context-sensitive help should always be available.
- Arbitrary Fault Capability - Today's tighter safety margins and the need to provide concise explanations of each relay operation means that short circuit programs must be able to easily analyze any fault conditions that occur in the field in addition to conventional three-phase, single-phase-to-ground, and phase-to-phase faults.
- Complete Network Model - It must be possible to model every power system element without exception and compromise. Such a power system model includes the phase shifts introduced by transformers, differing negative sequence data when appropriate, off-nominal transformer phase and tap ratios, bus ties, and transmission line charging.
- Contingency Network Changes - To use human and computer resources efficiently, the program must be capable of modifying the network incrementally. Changes including removal of shunts, removal of lines (with proper consideration of zero-sequence mutual coupling), breaker opening, and insertion of mid-line nodes must be done without reconstructing the entire system.
- ANSI Standard X/R Ratios - As breakers are operated closer and closer to their ratings, it is imperative that a breaker's suitability for the application be tested against standards.
- On-Demand Reporting - The program must be capable of displaying complete results for any fault at any location. Further, it should be possible to display these results in the per unit system or in engineering units. Common analytical outputs, such as three times the zero-sequence current and MVA flows, should also be available.
- Full-Screen Data Editing - It is no longer acceptable to force the user to be concerned with putting numbers in specific columns or rows. A full-screen editor that allows the user to concentrate on the data rather than the program requirements is essential.
Innovative Features
CAI (along with its extensive client base) is continuing to invent and implement new features. Typical innovative features include:
- Monitors - Monitors are like recording meters and may be placed at arbitrary locations on the network. When a series of faults is applied, each monitor remembers the fault and network changes, if any, that produced the maximum and minimum fault current at that location. A monitor stores this information for each phase and sequence. The results can be used to size breakers and set protective relays at the monitored locations. The maximum current might be used to determine interrupting capacities, while the minimum fault current may be useful in determining correct pick-up settings.
- Macro Programing Language - Relay setting is often called an art. The results that are required to set a relay vary from relay to relay and engineer to engineer. Consequently, it is impossible for any program to meet all the engineering needs with a fixed set of options. SC solves this problem by providing a flexible "macro" capability that allows a user to write "programs" to accomplish general tasks. A macro to fault all the buses around a particular location is a typical example. Because "arguments" can be passed to a macro, each macro can be used at many different locations. Operators, which act as specialized "do" loops, can be used to repeat operations for various power system elements. Macros may be used in the definition of other macros. As a result, entire studies suited to your own needs may be defined without reprogramming.
- Display of Results - Often an engineer is forced to pick up his hand calculator to compute some number that is a combination of those reported by the program. SC has a feature that allows the user to define and display an arbitrary expression of quantities computed by the program. Frequently used expressions may be combined with macros to create a permanent facility to display unique sets of results. · Tables - Occasionally it is desirable to prepare a custom report or to send results to another program such as a spreadsheet or data base. CAI has added a feature to SC that allows the program to generate arbitrary "tables" of information. Used in conjunction with macros and the display_results command, an unlimited variety of reports can be generated.
Data Conversion
Often, short circuit data have been stored in a format suitable for use with another short circuit program. While these programs may not offer many of the features of the TRANSMISSION 2000® SC program, it is often much easier to begin with these data. CAI offers a program to convert Westinghouse and Philadelphia Electric format short circuit data into SC's format. Alternatively, you may wish to have CAI do the initial conversion since this is a one-time effort. CAI will also provide an estimate for converting data in other formats.
Operating Requirements
The TRANSMISSION 2000® SC program is designed to run on Intel-based personal computers running Microsoft Windows. You will also need:
- at least 4 MB of memory
- a hard disk
Pricing Information
The single-copy price of the TRANSMISSION 2000® SC program includes one year of warranty, maintenance, and upgrade service. Multiple copy discounts, corporate licenses, short- and long-term rentals, and follow-on maintenance contracts are available. The program is supplied under an irrevocable, restricted license; copies of the license agreement are available for review. A demonstration package is available and includes a sample copy of the program, instructions, and a User's Reference Manual. Please call us for up-to-date prices.
Training
Training on the operation and use of this program is available at either our location or yours. CAI will also provide consulting services related to the program. For example, you may find it desirable to have CAI personnel help construct your initial data case since this is a one-time investment of labor. Please call us for more information and pricing.
Other Programs in the TRANSMISSION 2000® Series
The TRANSMISSION 2000® SC program is only one of the programs CAI offers for personal computer use. Power Flow, Line Constants, Power Flow Reduction and Data Conversion, Constrained Economic Dispatch, Short Circuit Reduction, Protection Analysis, Transient Stability, and One-Line Diagram programs are also available.
Ordering and Additional Information
To place an order or obtain additional information, please contact:
- Stephen S. Miller, P.E.
- Commonwealth Associates, Inc.
- P.O. Box 1124
- Jackson, MI 49204-1124
- Tel.: (517) 788-3676
- Fax: (517) 788-3003
- E-mail: Stephen S. Miller