Capacitive Behavior of Electrical Power Systems with Distributed Nonlinear Loads

The change in the electrical nature of the loads together with the loss of linearity are increasingly common phenomena in buildings, which requires special attention during the design phase of the electrical system in order to avoid problems in the management of reactive power flows and to better manage the power quality of the system. The presence of distributed nonlinear loads determine unusual behavior in terms of reactive power flux for the high harmonic distortion and for the capacitive behavior of the loads. Often the reactive power measurement in electrical systems serving tertiary or commercial buildings shows capacitive behavior with reactive power input from the private electrical system to the public grid. The goal of the paper is to analyze the behavior of power systems supplying non-linear distributed loads with harmonic distortion and capacitive behavior, highlighting when such behavior is real and when it is only apparent because it is conditioned by the incorrect measurement of the power factor. If the behavior is truly capacitive, the problem can be solved by replacing the power factor correction systems with static compensators that are able to compensate reactive power for both capacitive and inductive behavior, working on all 4 quadrants. At the end, a real case study shows the unusual behavior of the distributed non-linear loads.