Chapter Forty-One: Part VII: Voltage Sags and Dips, Power Quality - Chapter Forty-One: A Power Quality Instrument for the Smart Grid Monitoring based on Higher-Order Statistics

Abstract

This chapter proposes a virtual instrument for PQ assessment based on higher-order statistics. Accompanied by a new global index, the instrument implements a monitoring strategy that triggers a measurement procedure when an electrical fault is present and a local predefined threshold is surpassed. The method helps to classify events and continuous disturbances by tracking deviations in statistical parameters from their ideal steady-state values. Designed in LabVIEWTM, the user interface includes online graphs showing variance, skewness, and kurtosis, along with hybrid representations of variance versus the cited higher-order statistics. Based on a 50 Hz 100-signal battery, which gathers different types of electrical disturbances, the instrument was validated during online measurement sessions. Using stat-vs.-stat graphs that implement cycle-to cycle surveillance, results are depicted in 2D. The graphs show that voltage sags and transients can be classified within different clusters, with a low level of uncertainty. These visualization features allow the operator to view the relevant data objectively during an online monitoring session and, if needed, enhance the report with additional data, for example if they need to claim for economic losses and potential breaches of contract.