SYSTEM MONITORING EXPERT-SYSTEM

With the privatisation of the Electricity Supply Industry in England a nd Wales in 1990, there is an increasing requirement for the National Grid Company (NGC) to operate the transmission system more economicall y without compromise of system reliability. This often means that the system has to be operated close to its defined security limits, which incorporate robustness against credible faults. An important task in p ower system operation is to decide whether the system is currently ope rating safely, critically or unsafely. If the system is safe, it is of further interest to know whether following an unforeseen disturbance (e.g. outage of lines, transformers, generators or possibly bus-bars) the system will still remain in a safe operating condition. Ar the sam e time, it is required to operate the system in an economic manner. In order to monitor the security and economy of the system, the question arises as to what the important performance parameters are. From the practical point of view, all these parameters need to be combined to g ive an overall rating of the system stare which relates to the need fo r action by the control engineer. An insight into the causes of insecu rity or uneconomic operation must also be provided to aid in the selec tion of appropriate control actions. This paper describes the research and development for a prototype expert system for the National Contro l Centre lo assist the NGC Control Engineers in assessing the overall stare of the transmission system. The ultimate objective is to produce a fully installed and supported decision support system. The required system will carry out on-line analyses of the power system state, ide ntify the most important problems and draw these to the attention of t he Senior Control Engineer. The expert system should also assist the c ontrol engineer in the assimilation of more detailed and specific supp orting data, through the use of structured and intelligent HCl techniq ues.