## 5 The Methodology of ASI
### The Predictive Module  
The algorithms that carry out the functions of the Predictive Module represent the central activities of the ASI. Briefly, the Predictive Module receives the system parameters from the Input Module, compares them with the system parameters obtained from the off-line simulations to establish the degree of severity of an event.  
There are quite a number of activities involved in this work of the Predictive Module or more precisely its algorithms. Some of these activities are of a unique character such as data mining and pattern recognition. It is evident that the Predictive Module is the engine that drives the ASI. However, the algorithms required for this purpose have yet to be developed and then tested to make sure that the activities involved can be executed in the time available for the event to be identified and corrected by whatever remedial action is necessary. No hardware has been built.  
The first activity of the Predictive Module is to carry our simulations of system disturbances off-line and record these results. This activity involves the selection of the tests that will comprise the repository of events to be tested. Recourse can be made to data-mining technology for this activity. In a sense, the selection of the appropriate tests can be seen as similar to the method used by Hydro Quebec to select the tests on the 735 kV system to meet the design criteria [4].  
The results of these tests have come to be known as ASI Predictors. They are generated by the performance characteristics as part of the data-mining process. They are in the form of patterns produced by the transient-stability program that carries out these tests. It is important, therefore, to have a reliable transient-stability program to produce the significant patterns that comprise the repository of these tests. There is no need to carry out thousands of tests since a limited number of tests should be sufficient for this purpose of producing the ASI Predictors.  
The second activity of the Predictive Module is to compare the ASI Predictors - the results of the off-line tests - with the system parameters provided by the Input Module which have exhibited some degree of severity. Actually, both the ASI predictors and the system parameters are in the form of patterns and can be compared by a process called pattern recognition.  
The pattern of the ASI Predictors, when compared with those of the system parameters from the Input Module, leads to a recognition that a system disturbance of some gravity has occurred at this ASI location. Moreover, because of this pattern recognition, the gravity of this event can be estimated and even predicted by the ASI Predictors. This is the purpose of the ASI Predictors.  
Evidently, the link between the ASI Predictors and the system parameters is the key to the recognition of a system disturbance and its degree of severity.  
The third activity of the Predictive Module is to evaluate the degree of severity of a system disturbance by a comparison of the patterns of the ASI Predictor and the system parameters. In fact, this comparison will lead to a prediction of the severity of the event, namely A or E or X as already defined. The prediction will then be transferred to the Output Module.