use of synchronized phasor measurement system for monitoring

7/30/2019 Use of Synchronized Phasor Measurement System for Monitoring

http://slidepdf.com/reader/full/use-of-synchronized-phasor-measurement-system-for-monitoring 1/8

1

Use of Synchronized Phasor Measurement System for Monitoring

Power System Stability and System Dynamics in Real-time.

Bharat Bhargava

Armando Salazar Southern California Edison Co.

United States of AmericaSummary:

This paper / presentation is discussing the use of Synchronized Phasor Measurement

Technology, which is now being used for monitoring power system status and dynamic transient

event recording at Southern California Edison (SCE)off-line and in Real-time. This real time

monitoring system is expected to enhance the Transmission system reliability and provide wide

area visibility of the WECC system. The SPMS can enable SCE to monitor AC-DC power

transmission system reliability and improve reliability by monitoring the phase angles and

oscillations at several substations and two remote DC terminals. The system could be used for

real-time control in future. SCE has been working aggressively on this Synchronized Phasor

Measurement technology for over last twelve years and has installed a network of Phasor

Measurement Units (PMUs), obtains data from eighteen Phasor Measurement Units (PMUs) and

has installed two Phasor Data Concentrators (PDC) on its system. The data from the PMUs/PDCs

is now being collected and being used for monitoring and analysis of the system events.

Recently SCE has developed this tool called “SMART”, which enables SCE to view the phasor

measurement system data in real-time. SCE also obtains phasor measurement data from

Bonneville Power Administration Grand Coulee generating substation, which is over 900 miles

away, and close to the Northern HVDC Pacific Inter-tie terminal and monitors the phase angle

between the north and the south HVDC Pacific Inter-tie terminals. Monitoring these angle

separation is a very useful way of monitoring the stress on the WECC North-South system.

SCE is continuing to work on this technology with Bonneville Power Administration (BPA) and

Los Angeles Water and Power to investigate the possibility implementing it for real-time

monitoring. SCE is also working with other Western Electric Coordinating Council (WECC)

members for information exchange. It is believed that the technology has great potentials for

enhancing power system stability and power transmission system capability of an AC-DC inter-tie

system. This technology is also being used for monitoring the system stability and resulting

information can assist in avoiding major system disturbances like the one that occurred on August

10, 1996 in WECC and on August 14, 2003 in Northeast United States and Canada.

Contact / Author’s Information

Bharat Bhargava, Consulting Engineer

Tel: 626.302.8684; [email protected]

Armando Salazar, Senior Engineer

Tel: 626.302.8945; [email protected]

©2008 IEEE.



2

Introduction

Operation of electric power systems has become increasingly complex as the load growth

continues and additional market forces are coming into play. Deregulation and demand for

renewable and distributed resources is putting additional challenges in maintenance of the

reliability. On the other hand, the demand for higher reliability and power quality is increasing as

the industrial consumers add power electronics driven sensitive loads. Also, under the competitivederegulated market conditions, the utilities are finding it more difficult to plan and upgrade the

transmission systems as in the past and are unable to keep up with the growing loads and the added

generation. The power systems have also become so inter-dependent that the events in one area can

cascade and have significant impact on other remote areas. This was recently witnessed in

Northeast US blackout, which occurred on August 14, 2003. This change in the industry is putting

pressures and development of new tools to monitor wide area system stability and reliability is

becoming very essential.

The advances in the field of communications, computers and Global Positional System(GPS) technologies have enabled the development and use of Synchronized Phasor Measurement

technology in monitoring and managing dynamic system security of large power systems [Ref. 1-

5]. Southern California Edison (SCE) Co., which is part of the Western Electric Coordinating

Council in United States, has been working on the “Synchronized Phasor MeasurementTechnology” for last twelve years and has made substantial development in tools for visualizing

and analyzing the system dynamics. SCE has now a fairly good SPMS system installed at its key

locations and has installed a network of Phasor Measurement Units, Phasor Data Concentrators, a

high speed reliable fiber optic communication system and suitable data storage servers to collect

the phasor data. SCE also exchanges data from a Phasor Data Concentrator installed by Bonneville

Power

SCE Synchronized Phasor Measurement System (SPMS)

As a result of a large-scale WECC disturbance in August 1996, SCE began moreaggressively researching wide area measurement technologies. The initial goal of this effort with

WECC and EPRI was to monitor and analyze system events or disturbances. Since that time, SCEhas installed eighteen phasor measurement units (PMU) at all of its major 500kV and 230kV

substations, two BPA Phasor Data Concentrators, recorded data for most WECC events (since

1996), developed an off-line analysis tool for planning and operator training (Power System

Outlook), and a real-time operations tool (SCE SMART®) that is deployed in SCE’s Grid Control

Center. Figure 1 shows the Phasor Measurement units installed with in SCE. The Phasor Data

Concentrators are installed in SCE Grid Control Center in Alhambra.

SCE is currently working with the California Independent System Operator (CAISO) to receive

reliable data that CAISO collects from other WECC entities. SCE has a limited capability link

with Bonneville Power Administration (BPA) to exchange information with one of the main power

stations in BPA’s territory. This link is essential for determining North-South power flows and

WECC system stress conditions. The quality of this link is adequate for RD&D, but unfortunately,

does not satisfy the reliability requirements necessary for operations. SCE is working with otherWECC entities to improve data interchange.

SCE believes that this Synchronized Phasor Measurement (SPM) technology has potentialto reduce blackouts in future, provide full visibility of the entire system to operators and is needed

to monitor all essential dynamics that occurs in the power system. It is fast enough to providecapability of closed loop wide area control which may become essential in future power systems.



3

Figure 1: Phasor Measurement units installed in SCE (as of 2007)

SCE Program Capabilities –present and future (proposed)*:

Currently the two programs developed by SCE have the following capabilities.Additional capabilities, not underlined in the list, will be added in future.

P ower S ystem Outlook program ( PSO ) - Off-line Applications:

Presently available Monitoring system stress (Phase angle separations)

Monitoring voltage support at critical locations

Post disturbance analysis (what operated correctly or incorrectly) Monitoring modal oscillations and modal damping

Monitoring dynamic power swings

Future planned enhancements

Model validation/establishing limits using off-line analysis tools

System status summary

Monitoring machine excitation and governor systems

System Voltage and reactive power management

Pattern recognition and AI tools for quick event analysis

System load response to voltage and frequency variations

S ynchronized M easurements and A nalysis in Real T ime ( SMART )

Presently available

Monitoring system stress (Phase angle separations)

Monitoring voltage support at critical locations Monitoring path flows, frequency, df/dt



4

Post disturbance analysis (what operated correctly or incorrectly)

Operator Training tools – replay of past events Planning and Operational capability – replay of future simulated events

Future planned enhancements

Alarms and system flow views Monitoring modal oscillations and modal damping

Model validation/establishing limits using off-line analysis tools System Voltage and reactive power management

Pattern recognition and AI tools for quick event analysis

System load response to voltage and frequency variations

* The underlined applications are already available in the above programs

SCE Power System Outlook Program (PSO)

Power System Outlook was developed in 2000, to understand the data captured by SCE’s

SPMS and provide information usable for engineering and planning. The software provides off-line viewing and playback capabilities for data captured on all monitored circuits and features the

ability to determine: currents, power, reactive power, frequency/frequency deviation, df/dt at allPMU locations, phase angle difference from selectable bus reference, percent deviation for voltage,

current, power, reactive power and a voltage phasor display. More recent additions to the list

include: modes of oscillations, damping of identified modes, time constant for identified modes,

relationship analysis, data extraction into Microsoft Excel®

files, power in specific frequency band

(time domain), power vector replay at PMU location, and viewing and validation with GE’s PSLF

simulated events. The capabilities of PSO have enabled SCE’s engineers to better understand what

the phasor data means and have led directly to the development of a real-time system operations

tool with analytical capabilities. The tool is also being utilized in the studies for incorporating

4500 MW renewable wind generation. Future applications of this technology will include

intelligent control of bulk power components, remedial action schemes, and eventually, closed-loop control.

Figure 2: SCE Power System Outlook - Modes of Oscillation, Damping and Time

Constant for the August 4, 2000 dynamic event. The event had low dam-ping for

the WECC North-South oscillatory mode.



5

-45.00000

-33.00000

-21.00000

-9.00000

3.00000

15.00000

0 0.2490234 0.4980469 0.7470703 0.9960938 1.245117 1.494141

Frequency (Hz)

Midway1

Midway2

Midway3

Lugo1

Lugo2

Pardee

Most Dominant Mode is 0.286 Hz ; Undamped Freq is 0.287 Hz ; Damping (%) = ; Time Const = 32.94 sec

08/04/00 Event at 12:55 Pacific Time (08/04/00 at 19:55 GMT ) Bandwidth 0 - 1.5

Figure 3: SCE Power System Outlook – FFT analysis of power flows on the 500 kV lines at

Vincent substation for the above event. This event had low damping of the WECC North-

South mode.

SCE Synchronized Measurement and Analysis in Real Time (SCE SMART ®)

The next logical step in the progression of SCE’s synchronized phasor measurement

system was to develop a real-time tool for system operations and decision making. SCE SMART ®

provides operators and engineers with real-time (30 scans per second), synchronized data on

system stress and stability. SCE’s Grid Control Center is currently using the software to monitor

voltage, frequency, power imports and path flows.

Figure 4: SCE SMART ®

- Phasor voltage angle plot. The reference is BPA

Grand Coulee. SCE phasors lag between 55 to 75 degrees



6

SCE SMART ®

also features many of the analytical capabilities of the Power Systems

Outlook software, including: voltage, currents on monitored circuits, power, reactive power,

frequency and frequency deviation, df/dt at all PMU locations, phase angle difference from

referenced bus, percent deviation for voltage and current, and a voltage phasor display. SCE

SMART ®

can also be used for event recording, continuous data archiving, and analyzing power

system dynamic behavior. SCE is currently working to incorporate all of the analytical functions

of its off-line PSO software into the real-time applications.SCE SMART

®was designed to operate on Windows NT and XP with minimum hardware

requirements. It can run any BPA phasor file format (IEEE 1344) in real time or stored file

playback as a phasor file (dst) file.

Figure 5: Voltage profile and Frequency from SCE SMART ®

program


- Monitored Path Flows from SCE SMART ®

program



7


operating in SCE’s Grid Control Center

The SCE SMART®

and PSO are highly advanced software packages, they continue to be

part of SCE’s Research, Development and Demonstration portfolio, and are not commercialized

products. These products and the recorded events have enabled SCE to better understand its

system and WECC system characteristics. SCE has freely provided PSO to electric utilities,independent system operators and universities to encourage the development of advanced systems

technologies. Nonetheless, more RD&D is essential to fully understand and utilize the data

provided by phasor measurement units and other time-synchronized devices. SCE is committed to

advancing this effort and invites others to participate in this endeavor.

Note/Disclaimer

This paper represents the views of theirs authors and does not necessarily represent the

views of Southern California Edison Co. or its parent organization Edison International.

References:

[1] Phadke, A. G. Ibrahim M, Hibka, T., “Fundamental Basis for Distance Relaying withSymmetrical Components”, IEEE PA&S Transaction, Vol. PAS-96, No.2, March/April, 1977.

[2] Missout, G., Beland, J., Bedard, G., Lafleur, Y., “Dynamic Measurements of the Absolute

Voltage Angle on Long Transmission Lines”, IEEE Transaction, PA&S, November, 1981.

[3] Phadke, A. G., Thorp, J.S., Adamiak, M.G., “A New Measurement Technique for Tracking

Voltage Phasors, Local System Frequency and Rate of Change of Frequency”’ IEEE PA&S

Transaction, Vol. PAS-102 No.5, May, 1983,pp 1025-1038.

[4} Schulz, R.P., Van Slyck, L.S., Horowitz, S.H., “Potential Applications of Fast PhasorMeasurements on Utility Systems”, IEEE PICA, 1989.

[5] Phadke, A.G., “Synchronized Phasor Measurements In Power Systems”, IEEE Computer

Applications In Power, Vol. 6, Number 2, pp 10-15, April, 1993.

[6] R. L. Cresap and W. A. Mittelstadt, “Small Signal Modulation of the Pacific HVDC

Intertie”, IEEE Trans. PAS, Vol. 95, pp. 536 - 541, 1976.[7] R. L. Cresap and J. F. Hauer, “Emergence of a new swing Mode in the Western Power

Systems”, IEEE Trans. PAS, Vol. PAS 100, April 1981, pp. 2037- 2045.

Bharat Bhargava

Mr. Bharat Bhargava is a Consulting Engineer in the Technology Integration group of

Transmission and Distribution Business Unit of Southern California Edison Company in Rosemead,

California, where he has worked for the last thirty years. He is actively involved in phasor



8

measurements, transient analysis of power system, SSR studies, System Dynamics studies, Power

Quality, Railway Electrification, capacitor switching and Insulation Coordination studies, etc.

Mr. Bhargava graduated from Delhi University in 1961 with a Masters from Rensselear

Polytechnic Institute in 1976. He worked with the UP State Electricity Board in India from 1961 to

1975. Mr. Bhargava is a Senior Member of PAS, IAS Communication and Vehicular Societies of

IEEE and a Member of CIGRE.

Armando Salazar

Mr. Armando Salazar is a research engineer in the Engineering Advancement Group of

Southern California Edison (SCE) working in the Synchronized Phasor Measurement System project.

He received his Electrical Engineering degree in Power Systems from the National University of

Colombia. Before joining Edison, he was an Energy Consultant in South America. For 6 years, he

worked for the Latin American Energy Organization (OLADE). He also worked for the Bogotá

Power Company (EEB). Currently he is pursuing his Master degree in Power Systems at Kansas StateUniversity (KSU). He is an IEEE Member and a registered professional Electrical Engineer in the

State of California.

use of synchronized phasor measurement system for monitoring

Documents