Phasor Measurement Units

1. Phasor Measurement Units Hesen Liu, Minh Nguyen, Ryan Russel, Mathew Stinnett, Micah Till, and Nicholas Zamudio

2. Nicholas Zamudio History and Basic Theory

3. Definition of Phasors • A phasor is a way of representing a sinusoidal function • Utilizing Euler’s Formula, a phasor maps a sinusoidal function to the complex plane • The use of phasors, as well as the introduction of the term, in electrical circuits can be traced back to a paper written in 1893 by Charles Proteus Steinmetz

4. General Theory of Synchrophasors • Within a given power system, synchrophasors allow the measurements of circuit properties. • A phasor measurement unit (PMU) is used to calculate synchrophasors • PMUs were invented by Dr. Arun G. Phadke and Dr. James S. Thorp at Virginia Tech in 1988. • Macrodyne built the first PMU in 1992 • The PMUs measure real time circuit properties with respect to a time reference provide via a GPS system. • Phasors will either represent three-phase voltage or current, and therefore will require three separate electrical connections.

5. Phasor Networks • A typical phasor network consists of PMUs, PDCs (phasor data concentrators), and supervisory control and data acquisition system at a central control facility. • Phasor data collected either on-site or at centralized locations utilizing data concentrator technologies. This data is sent to regional monitoring system maintained by the local independent system operator. • PMUs connects to PDCs which sends data to either SCADA or WAMS servers

6. Architecture of Wide Area Network • Wide area measurements systems were first developed in 2000 by the Bonneville Power Administration. • A definition of WAMS was introduced by Hauer from BPA/Pacific NW National Labs: “The WAMS effort is a strategic effort to meet critical information needs of the changing power system”. • Typical wide area measurement system (WAMS) utilizes a reliable communication system that connects power stations, network control centers, and sub stations. • Consists of three fundamental processes: data acquisition, data transmission, and data processing.

7. Applications of Phasor Networks • Used for power system automation (smart grids) • Load control to manage power delivery • Fault detection (preventing outages) • Wide are measurement and control

8. Mihn Nguyen State of the Art Designs

9. System Design Overview • PMU technology is designed to provides phasor (both magnitude and phase angel) information in real time. • PDC is designed to synchronize and collect real time phasor data streams for use by Synchrophasor applications. • The data is then transmitted to a regional monitoring system which normally maintained by the local Independent System Operator (ISO). • ISO will monitor phasor data from individual PMU’s. • The monitoring system is a designed to provide accurate means of establishing controls for power flow from energy generation sources. • Phasor Data Concentrator (PDC

10. Schweitzer (SEL Inc.) . SEL offers many different PMU products for different purposes. They consists of Relays with PMU capability and Standalone PMU’s Price Range $1000 - $5000

11. Key Benefits of their PMUs . • Offer many different PMU products for different purposes • Lower Prices • Flexible Communications/Designs • High-Speed, Secure Line Current Differential Protection • Synchrophasor Measurements to Increase Asset Utilization • UseIEEE C37.118 format with 1–60 messages per second or SEL Fast Message format for interleaved communications. Apply direct relay-to-relay synchrophasors for wide-area-based control without additional devices

12. GE Multilin Price Range $8000 - $15000

13. Key Benefits of their PMU designs • High-speed inter-relay communications • Ambient temperature monitoring with alarm • Five zone quad or mho, phase and ground distance protection • Reliable and secure protection on lines equipped with series compensation • Exceeds the latest IEEE C37.118 standard for PMU measurement devices with a TVE of less than 1%, Protection and Metering class synchrophasors and multi-cast IEC 61850-90-5 support

14. ABB • ABB offers only standalone phasor measurement units

15. Key Benefits of their PMU designs • Protective relay technology and EMC noise • Frequency, frequency error, and rate of change of frequency • Synchrophasor data streaming per IEEE C37.118 and IEEE 1344 standard • Built-in GPS clock module for synchronized sampling of terminals in different substations • Flexible system configuration through integrated protection and control in one IED • Order form, so you can customized your PMU to your suited needs

16. Ryan Russell Impacts of PMUs

17. Benefits • Real-Time Analysis • Wide Area Monitoring Systems (WAMS) • Improve control/efficiency • Failure Analysis

18. Real-Time Analysis • Synchrophasors allow operators to track current and voltage levels in phase in real time

19. Wide Area Monitoring Systems (WAMS) • Improve power system operation • Maximize transmission line power • Reduce the risk of failure

20. Improve control/efficiency • EMS software can fix problems without operator present

21. Failure Analysis • 2003 East Coast Blackout • Synchrophasors allow operators to see how the failure occurred

22. Disadvantages • Cost • Requires outages to install

23. Cost • Synchrophasors - $2,000-3,000 • N60 Network Stabilizer - ~$8,000 • Software • 1 User - $1,500 • Site License - $45,000-60,000 • PMU installation - $100,000 – 200,000

24. Requires outages to install • Scheduled outages to install system • Takes lots of time and money

25. Mathew Stinnett Research and Development

26. Today’s Restrictions • Grid coverage • Outages required for installation • Lack of control applications • Collaboration between academia and industry

27. Tomorrow’s Vision • Installation of PMU’s across the grid • Cheaper and more efficient PMU’s • Cooperation between industry and academia

28. Micah Till PMU Applications

29. The Tennessee Valley Authority • Provided funding for initial PMU research • Early adopter of PMU technology on the grid • Creator of superPDC phasor data concentrator • Software is now openPDC owned by GPA • Acting national PMU data repository • Collects data from over 100 PMUs • Receives over 4 GB for every 3 hour period

30. The North American SynchroPhasor Initiative • NASPI is a collaborative effort between the DOE, NERC, industry stakeholders, and researchers • Provides a forum to discuss synchrophasor research, implementation, and application tools • Funding officially ended but additional meetings have been scheduled due to popular demand

31. The Frequency Monitoring Network • PMUs were developed at VT in the late 1980s • From 2000 to 2003 researchers worked to develop an FDR • Single-phase distribution measurements • High accuracy surpassing most PMU devices • Simple installation • 120 V AC outlet • GPS Antenna • Internet connection

32. The Frequency Monitoring Network • Established 2004 • Over 100 PMUs installed across American grids • Over 80 in EI • Event triangulation • Oscillation mode identification • Disturbance Scenario reconstruction • Tool for NERC frequency response compliance

33. The Frequency Monitoring Network

34. Hesen Liu Related Research Papers

35. Published in IEEE Transactions on Smart Grid, in 2010 Wide-Area Frequency Monitoring Network (FNET) Architecture and Applications

36. Brief Ideas • Why does the power system need WAMS? Wide-area monitoring systems (WAMS) utilizing synchrophasor measurements can help with understanding, forecasting, or even controlling the status of power grid stability in real-time. • What is FNET? 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. • What kinds of measurement data can be collected from FNET? Three kinds of data: Frequency data, Voltage data and Angle data. The sampling rate: 10 points in one second.

37. Building blocks of the FNET system

38. FNET Applications • FNET applications can be divided into real-time applications and non-real-time by their response time frame. Real-time applications require response within seconds or even subseconds after receiving the data, while non-real-time applications have more flexible timing requirements.

39. 1st Application • Frequency Monitoring Interface The frequency monitoring interface module is one of the real time applications. GUI interface for display FDR Selection Channel Data Query Window

40. 2ndApplication • Event Trigger and Event Location • The FNET event trigger module detects such phenomena by continuously scanning the incoming FDR records; thus, it is located in the real-time application layer. The scanning window calculates the derivative of 10 s worth of data. • The event location method is based on a geometrical triangulation algorithm making use of the time difference of arrival (TDOA).

41. 3rdApplication • Interarea Oscillation Trigger Power system oscillations can be associated with events such as generation trips and load shedding, but they can also be ambient. The FNET system creates a separate path for treating the oscillation data. Because of the high accuracy that FNET possesses on measuring system dynamics, power system oscillations can be monitored from both FNET phase angle recordings and FNET frequency recordings. Angle oscillation monitoring by FNET Frequency oscillation monitoring by FNET

42. 4th Application • InterareaOscillation Modal Analysis The interarea oscillation modal analysis module starts functioning after receiving oscillation data from the oscillation trigger. The matrix pencil approach, because of its robustness to noise, is used as the signal decomposition tool for modal analysis.

43. 5th Application • Event Visualization Frequency disturbance events have a geographically distributed impact, as the electromechanical waves propagate throughout the power system in time and space. It is therefore beneficial for the grid operators to have intuitive visualization of the cascading response.

44. 5th Application

45. 6th Application • Web Service The FNET Web service integrates visualization components such as a frequency table display, map display, and map gradient. It provides an educational platform for researchers, grid operators, and regulators to better understand the power system status in a wide-area perspective.

46. Summary • The FNET system was originally built as a power grid wide area monitoring system specifically applied to frequency monitoring. The FNET system’s potential for power system dynamic monitoring, stability estimation, real-time control and smart grid solutions are currently being explored.

47. Questions?