## State Estimation and Voltage Security Monitoring Using Synchronized Phasor Measurements (2001)

### BibTeX

@MISC{Liu01stateestimation,

author = {Yilu Liu and Lamine Mili and Jaime De La Ree and Reynaldo Francisco Nuqui and Reynaldo Francisco Nuqui},

title = {State Estimation and Voltage Security Monitoring Using Synchronized Phasor Measurements},

year = {2001}

}

### OpenURL

### Abstract

The phasor measurement unit (PMU) is considered to be one of the most important measuring devices in the future of power systems. The distinction comes from its unique ability to provide synchronized phasor measurements of voltages and currents from widely dispersed locations in an electric power grid. The commercialization of the global positioning satellite (GPS) with accuracy of timing pulses in the order of 1 microsecond made possible the commercial production of phasor measurement units. Simulations and field experiences suggest that PMUs can revolutionize the way power systems are monitored and controlled. However, it is perceived that costs and communication links will affect the number of PMUs to be installed in any power system. Furthermore, defining the appropriate PMU system application is a utility problem that must be resolved. This thesis will address two key issues in any PMU initiative: placement and system applications. A novel method of PMU placement based on incomplete observability using graph theoretic approach is proposed. The objective is to reduce the required number of PMUs by intentionally creating widely dispersed pockets of unobserved buses in the network. Observable buses enveloped such pockets of unobserved regions thus enabling the interpolation of the unknown voltages. The concept of depth of unobservability is introduced. It is a general measure of the physical distance of unobserved buses from iii those known. The effects of depth of unobservability on the number of PMU placements and the errors in the estimation of unobserved buses will be shown. The extent and location of communication facilities affects the required number and optimal placement of PMUs. The pragmatic problem of restricting PMU placement only on buses with communic...

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Citation Context ...h is subsequently compared to computer simulation of the same event. Similarly, PMUs have provided detailed look on known oscillations that were not observed by traditional measurement devices before =-=[17]-=-. Its synchronized high-speed measurement capability has made it favorable for recording system events for after-the-fact reconstruction [57]. A decision tree based voltage security monitoring system ... |

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Citation Context ... [64]. The reader is referred to a book [56] that delivers a thorough discussion on modes of oscillations. Electricite de France has developed a “Coordinated Defense plan” against loss of synchron=-=ism [21]-=-. The scheme makes use of PMU voltage, phase angle and frequency measurements to initiate controlled islanding and load shedding to prevent major cascading events. Similarly, Tokyo Electric Power Comp... |

1 |
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Citation Context ...ntify residuals that are suspiciously high. The state estimator is rerun with these suspect measurements removed with the state estimate declared acceptable if the remaining residuals are permissible =-=[22]-=- [31]. The reader is referred to Mili [44] for a comparative study of various bad data detection techniques. The system must be observable by PMUs for the SE to estimate the state. Observability ensur... |