A Two-Step Compensation Method for Solving Short Circuit Problems

This paper reports on the development of a unified approach for the solution of all types of short circuit problems. The basic approach is to consider a fault condition -- a fault type or combination of fault types and associated line outages -- as modifications to the parameters of the branches of the prefault network. An extension, referred to as the two-step compensation method, of the conventional compensation scheme was developed to account for the balanced and unbalanced nature of-the modifications that networks undergo when faulted. The computationally efficient solution scheme was derived by using a decomposition of the modifications according to their balanced and unbalanced nature and exploiting the structural properties of the short circuit problem, notably sparsity. The solution approach is particularly useful for system-wide studies, in which specified fault conditions at a set of specified fault locations are analyzed sequentially, on large systems. A noteworthy feature of the proposed methodology is the natural manner in which mutuals are handled. Results of the application of this approach to investigate a variety of fault conditions on several systems, including a 2278 bus network, are presented.