Search

Improvements made to a relational database management system (DBMS) developed for real-time energy management and control systems for electric utilities are described. The focus is on the software performance improvement features and the dual database concept for coordinated updates. The discussion covers task structuring, buffer usage, active restructuring, and presolving of access routes. Some of these features are applicable to other real-time systems with large databases shared by many application programs. The extension of the DBMS design for use in a hierarchical real-time system is described. >

The current status of long term power system dynamic simulation at the conclusion of EPRI RP1469-1 project is summarized. Technical perspectives on the application history and simulation methodology are given first. The current status description concentrates on the program requirements, the power system models and the solution method. Discussions in relation to the actual project work are given throughout this paper, focusing upon future usage of the simulation. A number of recommendations are given to facilitate application.

An advanced Dispatcher Training Simulator (DTS) design which also facilitates software testing is described in this paper. In other EMS enviromnents, special software must be developed to support facility installation and new applications software testing. The DTS is designed such that no substantial changes are required in order for it to be used as a Software Testing Simulator (STS). The key to such a design is a flexible communication interface.

A description is given for recent microprocessor applications in Remote Terminal Unit (RTU) comunications and in master station equipment configuration control. The Communication Input Output Controller (CIOC) is used for RTU data acquisition and subsequent front end processing. With modular firmware, it can be programmed to handle arbitrary communication protocols and message structures. In communication with the CIOC is a Configuration Manager(CM). It monitors and controls the switching of major control equipment including the CIOC's. This enables either automatic or manually instructed substitution of spare items for failed items. Both the CIOC and the CM are microprocessor based. Integration testing of the applications has been conducted and satisfactory results have been obtained. Discussions are also given to indicate related future applications.

There is considerable interest in expanding the capability of transient stability simulation to extend the time range of simulation and to add more power system components. The EPRI projects RP 745 and RP 1208 extended transient stability simulation to the mid-and long-term range. Additional power system components have added both high-speed dynamics (dc converters, generator subtransients) and very low speed effects (boiler dynamics, AGC controls). This paper addresses the interfacing of the wide range of time frames. A measure of the time frames is defined and evaluated for power system components in the EPRI RP 1208 Transient/Midterm Stability Program. The limitations and capabilities of stability simulation to properly support the range of time frames is discussed. This work has been supported, in part, by EPRI projects RP 745, RP 1208 and RP 1469.

A database management system (DBMS) has been developed to support a major electric utility's operating and planning information requirements. Its structure is of the relational type, extended to suit the records relationship commonly found in power system applications. It has been tested to meet the real-time performance requirements of giving control responses within, 1-second, and providing a control system availability of 99.9 % or higher.

A number of steam turbine prime-mover models for extended system dynamics simulation has recently evolved and been documented from planning type of studies. Significant effort has been expended in the development resulting in some general awareness of this applicability. However, the effective model structure as affected by limited data, and individual dynamic response characteristics of these state-of-the-art models remain to be considered. It was not known how these models individually respond dynamically in terms of closed-loop response time and nonlinear effects such as dead-bands and limits. It was also not known how well these models can be used in a dispatcher training simulation. This paper presents computed results of individual unit dynamic responses of two such models out to several minutes. Computations simulating load following and breaker opening are included. The responses show nonlinear effects due to dead-bands in series with major control paths. The closed-loop response times are found to be not directly related to any single time parameter of the model. Effects and limitations of integration time steps and integration methods are illustrated. The results of the computational study show that the models can be adapted for dispatcher training simulation, and time steps can be as long as two seconds with appropriate choice of integration algorithm. Computational interface consideration for these models in other power system studies is also included in this paper.

A generalized methodology for modeling various system components in power system dynamics simulation studies is presented in this paper. One of the salient features of the method is its applicability to transient stability, mid-term dynamics simulation and long-term dynamics simulation. Also, the application of sparse matrix techniques to the computation of initial conditions is presented.

The application of electronic spreadsheet packages has been maturing with the increased usage of small or personal computers. However, little work has been done to explore the use of spreadsheet techniques in power system operation. In this paper the common spreadsheet concept used for answering the ``what if'' question is extended to conveniently answer the questions of ``what was'' or ``what will be'' in power control operation. Enhanced with features needed to support automated data collection and processing in a real-time electric utility control, the extended spreadsheet concept has been implemented in a delivered power control computer. This paper describes an approach to the implementation of the real-time spreadsheet and data storage software package. The intended uses are first described. The method of constructing a real-time spreadsheet using this package is illustrated with an example. The software tools included in the package are presented in substantial detail. The presentation of the software functions also illustrates the relationship of spreadsheet building to the control computer database.