Data Base Validation and Maintenance: Some Experiences During Acceptance Tests of a Large Power System Control Project

Abstract

Abstract To dispose of secure and consistent data is crucial for all the functions of a modern Power System Control Center /7/. The attention of the specialists has been up to now mostly focused on the detection, the identification and possibly the suppression of bad data coming from the field via the telecommunication channels, e.g. analog measurements and statuses. In fact, it is evident the danger of such a situation, where an important monitoring function (an alarm) is misled or a wrong control action is taken, due to the false on-line information. This paper, instead, deals with a perhaps less investigated, but not less important aspect: the validation of the static part of the Data Base and the detection of lacking data. The parameters of the electrical model (derived from off-line archives), the substation and network connectivity information, the digit-to-engineer-units conversion data and many other quantities related both to the power system and to the telecommunication subsystem, have to be accurately checked and their reciprocal consistence must be verified. This side of the problem is not trivial as far as: - the dimensions of the system grow up. In this case it is important to have good offline tools in order to increase the accuracy of the static data, also because the number of people, in chargeof collecting it, is enlarged. - the control project is commissioned to a manufacturer: in this case the presence of errors in the Data Base, or in the manufacturer software or in both can make problematic the sharing of responsibility. The new Power Generation and Transmission Control (PGTC) project of ENEL meets both the above requirements: the authors describe their two-years activity in preparing, securing and maintaining static data for the on-line Data Base and in carrying out acceptance tests vis-a-vis of the manufacturer. The attention is paid to the procedures adopted in order to avoid as many as possible conflicts of responsibility and to reach the basic confidence - beyond the contractual tests merely relevantto the monitoring functions - that the delivered system is really able to support the more sophisticated controlfunctions as the security analysis and the automatic corrective actions. The experience is reported about the most frequent ej: rors detected, their nature and origin and the way of identification. An accurate description then follows of the procedures set up at ENEL for checking and validating the data, which, prepared off-line, feed the on-line Data Base. A distinctive features of such a procedure is the cross checking among different categories of data (for example the teleacquisition subsystem data and the Man-Machine Subsystem Data), which hasproved to be very effective in detecting inconsistencies. Finally the authors present some results of their experiences, in form of recommendations to companies having similar problems. One of these is the usefulness of setting up simulated, electrically coherent, error free dynamic (or variable or foreground) data for testing purposes; and of making use of the State Estimator if available - already in the initial phase of the project, say during the telemetry installation, for the off-line validation and securing of the Data Base.