Correlational Analysis of Relationships Among Nodal Powers and Currents in a Power System

This paper concerns the analysis of the impact of nodal powers on currents flowing in the power system (PS). Two problems are considered here, i.e., Problem I—identifying the branches of the PS on which currents have magnitudes that strongly change with changes in nodal powers, characterized by magnitudes and arguments, and identifying nodes at which these powers exist, and Problem C—PS clustering from the point of view of the relationships between branch current magnitudes (BCMs) and nodal power magnitudes (nodal apparent powers—NAPs) or nodal power arguments (NPAs). The solution to Problem I may be useful for the modernization of the PS as well as in the practice of dispatchers. The solution to Problem C may be useful in system analyses. The analysis of the literature shows that the existing papers only touch on the earlier-formulated problems to a modest extent. In fact, those problems are not solved. The paper fills this gap by presenting methods for solving the given problems. Both considered problems are solved using data mining. The investigation of correlational relationships (CRs) between BCMs and NAPs as well as CRs between BCMs and NPAs is used. Any such strong CR indicates large changes in BCM with changes in NAP or NPA remaining in the considered CR. Nodes, which through NAPs are in CRs with BCM for a selected branch, are a cluster associated with this branch. The paper also considers clusters encompassing branches, for each of which BCMs are in CRs with the NAP of a given node. Similarly, when searching for clusters encompassing nodes, or clusters encompassing branches, in the aforementioned CRs, one considers NPAs instead of NAPs. The paper proposes methods for solving Problem I and Problem C, which allow (i) relatively simple detection of regularities in the PS with the provision of their statistical evaluation, which would be difficult or impossible in the case of other methods, and (ii) solving the indicated problems based only on measurement data, and do not require (i) performing flow calculations and (ii) large computational effort. The paper presents the properties of the methods on the examples of the IEEE 14-Bus Test System and IEEE 30-Bus Test System.