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9 - Networking technologies for wide-area measurement applications
- from Part III - Smart grid and wide-area networks
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- By Yi Deng, Virginia Polytechnic Institute and State University, USA, Hua Lin, Virginia Polytechnic Institute and State University, USA, Arun G. Phadke, Virginia Polytechnic Institute and State University, USA, Sandeep Shukla, Virginia Polytechnic Institute and State University, USA, James S. Thorp, Virginia Polytechnic Institute and State University, USA
- Edited by Ekram Hossain, University of Manitoba, Canada, Zhu Han, University of Houston, H. Vincent Poor, Princeton University, New Jersey
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- Book:
- Smart Grid Communications and Networking
- Published online:
- 05 January 2013
- Print publication:
- 24 May 2012, pp 205-233
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- Chapter
- Export citation
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Summary
Introduction
A wide-area measurement system (WAMS) consists of advanced measurement technology, the latest communication network infrastructure, and integrated operational framework. The supervisory control and data acquisition (SCADA) infrastructure for energy-management system (EMS) has been widely used in power systems for a long time. Some of the functionalities of an EMS are system state monitoring, tie-line bias control, and economic dispatch [1]. However, in recent years, various deficiencies of the existing SCADA-based EMS (such as quasi-steady-state calculation, non-synchronized data acquisition, and relatively low data transmission rate) have been pointed out. These defects make it impossible to sample the global state of a power system in real time. As more and more wide-area blackouts are reported, it is clear that acquiring real-time or wide-area state information would be needed in the future. The state information in terms of phasors of voltages and currents from a distributed wide area in real time is therefore critical for avoiding large-area disturbances by effecting wide-area control based on wide-area measurements.
The main enabler of WAMS is phasor measurement unit (PMU) technology. With the innovation of PMU, the problem of measuring the phasor quantities simultaneously from a wide area of distributed substations, also called ‘synchrophasor’, has been solved. At present, the PMU technology is one of the essential enablers for WAMS. It utilizes the availability of high-precision synchronized clock sources – extracted from global positioning system (GPS) receivers and samples the instantaneous analogue – quantities of voltage and current magnitudes and phase angles.