Formalizing the Repair Process 2 Concepts and Informal Deenitions 2.1 Diagnosis/repair Process

This paper deenes the model-based diagnosis and repair process. We consider repair (i.e. restoration of speciied system purposes) as the main goal of this process. Our goal is to deene how an intelligent agent integrates and schedules observations and actions in an interleaved way in order to guarantee a speciied system purpose. We deene a temporal framework where all concepts necessary to represent repair (actual, possible and plausible worlds, purpose, observations, actions and failures) can be integrated. Using these concepts we present an algorithm scheme describing the repair process. 1 Motivation We use an energy transmission network to illustrate several shortcomings of the current diagnosis concept. Figure 1 shows a substructure of a real 380 kV network. 1 Generators gi supply the network with energy distributed by lines li and bus bars bi. Transformers ti feed energy to consumers. Every crossing in Figure 1 marks a possible connection established by a power switch. Closed power switches are represented by dots. Lines are connected to bus bars by switches at points li ? bj. Some bus bars are doubled, hence a line can be connected to both of them. Common faults in such energy transmission networks are short circuits which cause a serious damage of components in the network if the faulty parts are not cut oo in time. Therefore, a protection system monitors the loads and trips the power switches if a dangerous overload is observed. Actions and measurements performed by the protection system are submitted to a central monitoring station. Voltages and loads of the bus bars are measured every second. We assume the following fault scenario: Due to a signiicant high overload caused by a short circuit the power switches at l1 ? b1 1 and l2 ? b4 2 are tripped. Since the breakdown costs are enormous, re-establishing the correct behavior as soon as possible 1 For a detailed description of model-based diagnosis in such networks see the report by 1], whom we thank for stimulating discussions on the diagnosis of these networks. b1 1 b1 2 q k g1 q l1 q b2 q k k t1 6 q l2 q b3 q k k t2 6 q l3 q b4 1 b4 2 q k k t3 6 q k k t4 6 q l4 q b5 1 b5 2 q k k t5 ? q k g2 Figure 1: Energy Transmission Net is the …