Southern California Edison Co. Rosemead, California 91770. United States of America. Abstract. This paper will present the use of Synchronized Phasor ...
Use of Synchronized Phasor Measurement System for Monitoring Transmission Reliability and Capability of SCE and WECC Network By Bharat Bhargava* Consulting Engineer Southern California Edison Co. Rosemead, California 91770 United States of America Abstract This paper will present the use of Synchronized Phasor Measurement System (SPMS) Technology which is an element of “Wide Area Measurement System (WAMS) Technology” for monitoring large power systems real-time. The Synchronized Phasor Measurement Technology has been in use at Southern California Edison Co. for last eight+ years and has recorded hundreds of significant events. The technology is also being used in several other electric power organizations like Bonneville Power Administration, American Electric Power, Entergy, Tennessee Valley Authority in America and EDF (France) etc. The technology has been evolving at a very fast rate for off-line applications, for recording system disturbances, for post-disturbance analysis etc. Several blackouts that occurred in US, Canada, Italy, and Sweden during 2003 have demonstrated the need of Wide Area Measurements and Monitoring Systems and the “Situational Awareness” required today to avoid system break-ups. These power blackouts have shown that events occurring in remote areas thousands of miles away have to be monitored otherwise can cause major system disturbances. The systems today are becoming more and more complex. They operate synchronized over a large area and often under severely stressed conditions. More and more active controls are being used not only on generators, but are also being applied on the Transmission systems. Applications of Flexible AC Transmission systems (FACTS), High Voltage DC systems, Independent Power Producers, Distributed Generations, and Utility Deregulation etc. are only adding to the complexity of the power system operations. On the other hand, the demand for reliable, stable power supply is increasing. Since the systems are much larger today and are becoming larger, the impact from their failures is much larger. The SPMS, which is an element of Wide Area Measurement System (WAMS) can enable Real-time monitoring of some of the following critical system operating indices which are essential for secure operation of a large power system: • Monitor, establish and operate within the static phase angle limits (system stress). • Monitor/ensure Critical Intermediate voltage support when operating at large phase angle separation • Monitor dynamic/transient phasor movements for dynamic/transient swings between different areas. • Monitor Modal inter-area oscillation frequencies and their modal damping. • Monitor path loadings and line flows and key tie line status etc. • Monitor and arm Special Protection Scheme (Remedial Action Scheme) operations Southern California Edison has developed “Power System Outlook” program that enables viewing and analysis of the recorded Phasor Measurement system data off-line. The program has the capability to merge files from different Phasor Data Concentrators, join files for viewing larger time span etc. The files recorded by SCE Phasor Measurement system are available to SCE personnel in matter of minutes. SCE is developing and implementing tools for viewing/analysis of this data real-time. SCE is also working with other utilities/organizations for interchange of data. In order to get full picture of a large system, it is important that measurements be available from strategic points and the data is interchanged among the operating utilities. The data from remote locations can be made available in the system operators in matter of fraction of a second. The presentation will demonstrate the SCE “Power System Outlook program” capability and review some of the interesting events that have been captured by the SPMS at SCE to illustrate the use of
this technology for monitoring some of the critical operating parameters listed above for increasing the operating reliability of a large power system. By monitoring of the stresses and other system conditions, the operators can also use this information to maximize power transfers on the congested paths and increase profit margins. Some Power Companies are progressing ahead even to take remedial actions, exercise controls on their systems. By real-time monitoring of frequencies and some other critical system operating parameters, it is believed that, the operators can be made aware of the high system stress, generation/load losses in remote areas, system separations or islanding, which can help them take appropriate measures in avoiding major system break-ups.
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