Algorithm for Screening Phasor Measurement Unit Data for Power System Events and Categories and Common Characteristics for Events Seen in Phasor Measurement Unit Relative Phase-Angle Differences and Frequency Signals

Abstract

A network of multiple phasor measurement units (PMU) was created, set up, and maintained by professors and students from the University of Texas at Austin to obtain actual power system measurements for power system analysis. The network is now located and maintained at Baylor University in Waco, Texas. Power system analysis in this report covers a variety of time ranges, such as short-term analysis for power system disturbances and their effects on power system behavior and long-term power system behavior using modal analysis. Modal analysis is the analysis of power system dynamic behavior under excitation from changes in the power system. The PMU data examined in this report is archived at 30 samples per second and is continuously measuring and recording voltage phasor data. Because of the high volume of PMU data generated by the network, it is difficult to localize and analyze power system abnormal events (large disturbance events) of interest that have been recorded by the network.The first objective of this report is to screen the PMU data for events. An algorithm was created using a variety of methods to detect power system events. The algorithm uses fast Fourier transform-, Yule-Walker-, and matrix-pencil-based methods to find events as well as a simple method to detect large swings in the PMU data.The second objective of the report is to identify and describe common characteristics extracted from power system events as measured by PMUs. The report describes category definitions based on visual analysis and extraction of numerical characteristics for each category. Category definitions based on visual inspection consist of two parts: events detected in voltage phase angle signals and frequency signals. In the voltage phase angle, events belong to one or more of the following proposed categories: impulse, transient, or step change. In the frequency, events belong to one or more of the following proposed categories: impulse, transient, or rise or drop in frequency. Some events belong to one category; some events belong to multiple categories, such as frequency drops caused by a sudden loss of generation that can also contain low-frequency oscillations. This type of event belongs to both the drop-in-frequency and transient categories.The numerical characteristics for each category and how these characteristics are used to create selection rules for the algorithm are also described. Trends in PMU data related to different levels and fluctuations in wind power output are also examined. vi This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

PMU Data Event Detection: A User Guide for Power Engineers

“…Frequency events will look different from the results for the phase angle shown above. Refer to Allen, Santoso, and Muljadi (2013) for examples of events in frequency data.…”

Detection techniques for data-level spoofing in GPS-based phasor measurement units

“…moving the receiver antennas [10]; 5) cryptographic techniques [11]; 6) And stability of the frequency, voltage and phase information in the phasor data [12]. Table 1.1 provides a summary of these traditional countermeasures and their limitations.…”

“…The University of Texas at Austin (UT-Austin) introduced an independent synchrophasor network ( Figure 5.2) to monitor abnormal events and analyze low-frequency oscillations from the electric power grid through PMU measurements taken at the customerlevel voltage (120 V) [12]. All measurements are taken at the customer-level voltage of 120 V [12]. The first column represents the time-tag provided by the GPS receiver, the other columns denote the magnitude, phase angle and frequency, respectively.…”

“…Map of texas PMU stations within the UT-Austin independent texas synchrophasor network[12] The time-stamped phasors from each PMU station are sent either through the public Internet or serial cables to the phasor data concentrators. The phasor data concentrator waits for data from all PMUs and stores the PMU data once it is received.…”

User Guide for PV Dynamic Model Simulation Written on PSCAD Platform

“…It is also timely, as the synchrophasor measurements to monitor these quantities are available and have been installed massively in the modern power system network. The fundamental understanding of power systems in references [2,3] and the concept and applications of synchrophasor measurement can be found in the references [4,6].…”