Jason Bank

Wide-Area Frequency Monitoring Network (FNET) Architecture and Applications

Recent developments in smart grid technology have spawned interest in the use of phasor measurement units to help create a reliable power system transmission and distribution infrastructure. Wide-area monitoring systems (WAMSs) utilizing synchrophasor measurements can help with understanding, forecasting, or even controlling the status of power grid stability in real-time. A power system frequency monitoring network (FNET) was first proposed in 2001 and was established in 2004. As a pioneering WAMS, it serves the entire North American power grid through advanced situational awareness techniques, such as real-time event alerts, accurate event location estimation, animated event visualization, and post event analysis. Several papers published in the past several years discussed the FNET structure and its functionality. This paper presents some of the latest implementations of FNETs applications, which add significant capacities to this system for observing power system problems.

Wide-area Frequency Based Event Location Estimation

This paper discusses the latest developments in wide-area frequency-based event location using FNET. FNET, meaning ldquoInternet based frequency monitoring networkrdquo, is a low cost and quickly deployable wide-area frequency measurement system with high dynamic accuracy. This project demonstrated the feasibility of using information from FNET to estimate the location of events in the electric grid. An on-line real time event detection tool using least squares methods was developed and tested on data from FNET. This paper outlines the methods used along with an examination of implementation feasibility.

Non-Parametric Power System Event Location Using Wide-Area Measurements

Previous work has shown that the study of the electromechanical wave signature of a power system perturbation, such as a generator trip, can lead to an understanding of how to approximate the origin of the perturbation (R.M. Gardner, et al., 2006). In this paper, a brief synopsis of FNET is presented along with an analysis of generator tripping events. The analysis is comprised of several non-parametric event location methods and resulting observations. The eventual goal of this research is to formulate a robust event location algorithm that can be used online and in real-time to locate with sufficient accuracy the hypocenter of power system events irrespective of utility boundaries

Generator Trip Identification Using Wide-Area Measurements and Historical Data Analysis

Changes in power system operating conditions cause dynamic changes in angle and frequency. These changes propagate through the system as disturbances in frequency as previously studied (J.S. Thorp, et al., 1998), (L. Huang, et al., 2001). The disturbances in system frequency travel with finite speed across the system area (M. Parashar, et al., 2004). Thus a sudden loss of generation in one area would be seen as a frequency disturbance in other areas of the power system. Through use of wide-area frequency measurements these traveling frequency disturbances can be observed and recorded. This paper focuses on the analysis of this recorded data and how the specific properties of a generator trip can be determined. Future generator trips can then be compared against the recorded frequency signatures to determine a probable match. In this way the trip location can be determined. This analysis and comparison process is capable of being completely automated to be used in real time to determine the health of the power system as a whole

Estimating Speed of Frequency Disturbance Propagation Through Transmission and Distribution Systems

Changes in power system operating conditions cause dynamic changes in angle and frequency. These changes propagate through the system as disturbances in frequency as previously studied (J.S. Thorp, et al., 1998), (L. Huang, et al., 2001). The disturbances in system frequency travel with finite speed across the system area (M. Parashar, et al., 2004). Thus a sudden loss of generation or load in one area would be seen as a frequency disturbance in other areas of the power system. Through use of wide-area frequency measurements these traveling frequency disturbances can be observed and recorded to be used for real time system analysis. Currently the majority of wide area measurements are taken by PMUs and similar devices at the transmission level. This paper focuses on the effects of performing these measurements at the distribution level and how this additional layer of the system can affect the measurements. It is important to note that the relevant effects of machine inertia are not considered in this study. Rather this paper focuses on system/line impedance in the determination of electromechanical wave propagation speed

Visualization and Classification of Power System Frequency Data Streams

Two challenges in the realization of the smart grid technology are the ability to visualize the deluge of expected data streams for global situational awareness; as well as the ability to detect disruptive and classify such events from spatially-distributed high-speed power system frequency measurements. This paper presents an interactive visualization model for high speed power system frequency data streams that displays both local and global views of the data streams for decision making process. It also presents a K-Median approach for clustering and identifying disruptive events in spatially distributed data streams. The results from experimental evaluation on a variety of datasets show that K-Median achieve better performance and empowers analysts with the ability to make sense of a deluge of frequency measurements in a real-time situation.

Angle Instability Detection in Power Systems With High-Wind Penetration Using Synchrophasor Measurements

The alternating current machines in a power system have the ability to remain synchronized following a severe disturbance such as loss of generations, line switching, or fault. This is described as power system transient stability. During system transients, the machines will accelerate or decelerate because of the mismatch between electrical torque and mechanical torque. Their power angles will travel and finally settle down to a new equilibrium, if the system has enough stored energy to absorb the disturbance, and rest the system at another steady state. In case of system instability, some machines will have aperiodic angular separation from the rest of the system and finally lose synchronization. Therefore, the power system transient stability is also called angle stability. The total system inertia is an essential force to rest the system transient. The inertias stored in all rotating masses that are connected to a power system, such as synchronous generators and induction motors, typically respond to disturbances voluntarily, without any control actions; however, several types of renewable generation, particularly those with power electronic interfaces, have an inertial response governed by a control function. To ensure bulk power system stability, there is a need to estimate the equivalent inertia available from a renewable generation plant. An equivalent voluntary inertia constant analogous to that of conventional rotating machines can be used to provide a readily understandable metric, such as the angle instabilities detections, because one of the most difficult obstacles for angle instability detection is the knowledge of the real-time generator inertias. This paper explores a method that utilizes synchrophasor measurements to estimate the equivalent inertia of a power source such as synchronous generators or wind turbine generators. This paper also investigates the angle instability detection method for a system with high wind power penetration using the synchrophasor measurements.

Visualization of wide area measurement information from the FNET system

Analysis of power system dynamics helps to understand the operation of a power system. Therefore, it is significant to design and develop advanced visualization tools to interpret frequency, voltage magnitude, and phase angle information so that it can be presented to the operators in an intuitive manner. On the basis of the measurement data collected by widely-distributed frequency disturbance recorders (FDRs), visualization tools have been implemented for the FNET system. A number of FNET visualization tools are discussed in this paper, including real-time visualization, animated event replay, visualization of oscillation mode analysis and visualization of propagation effects in two dimensional systems. These tools correlate the FDR measurements with their corresponding geographical information, and transform the combined matrices into different graphic formats using various computer techniques and programming languages. The graphics generated by these tools facilitate power system operation by allowing an operator to monitor power system dynamics, perform post-event analysis and identify modal oscillations more efficiently.

Development of a distribution level data acquisition system and preliminary results

With the development of smart grids and the deployment of their enabling technologies, improved data acquisition will be needed at the distribution level to understand the full impact of these changes. With this in mind, NREL has developed a high-speed measurement and data collection network targeted specifically at the distribution level. This network is based around adaptable, rugged measurement devices designed for deployment at a variety of low and medium voltage locations below the substation. Each of these devices is capable of real-time data transmission via an internet connection. This paper presents the data collection results and a preliminary data analysis, as well as a brief introduction to some of the distribution level visualization applications that have been developed based on the incoming data streams.

Development of a real-time, high-speed distribution level data acquisition system

With the development of smart grids and the deployment of their enabling technologies, improved data acquisition will be needed at the distribution level to understand the full impact of these changes. With this in mind, NREL has developed a high-speed measurement and data collection network targeted specifically at the distribution level. This network is based around adaptable, rugged measurement devices designed for deployment at a variety of low and medium voltage locations below the sub-station. Each of these devices is capable of real-time data transmission via an Internet connection. Additionally, several analysis and visualization applications have been developed around the incoming data streams.