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The Brazilian Wide Area Measurement System – Experience and Applications. Daniel Dotta email: dotta@ifsc.edu.br. Presentation Structure. Objective Wide Area Measurement System Overview Phasor Measurement Process Research going on at RPI The MedFasee Project
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The Brazilian Wide Area Measurement System – Experience and Applications Daniel Dotta email: dotta@ifsc.edu.br
Presentation Structure • Objective • Wide Area Measurement System Overview • Phasor Measurement Process • Research going on at RPI • The MedFasee Project • LVPMS and HVPMS prototypes • Blackout in the Brazilian Interconnected Power System • Selected Applications • Conclusions
Objective • To present an overview of the Brazilian experience with Wide Area Measurement Systems
Wide Area Measurement SystemOverview • Simultaneous signals measurements at remote geographic locations using PMUs (Phasor Measurement Units). • GPS time synchronized measurements • Data acquisition and handling in remote sites (PDC). • Upgrade rate (scanning) >> SCADA. • Allows dynamic monitoring and control of electric systems. • New paradigm for the system operation.
Phasor Definition • Complex number that represents a sine wave whose amplitude (X) and angular frequency (ω) are time-invariant • The phasor module is equal to the rms signal value and the phase angle is the signal phase to t=0.
Synchrophasors • Phasor measurements that occur at same time are called “synchrophasors”. Necessity of only one time reference – Synchronization! Task not trivial: Involves large distances and high time precision.
SCADA X WAMS(Comparasion) SCADA (Supervisory Control and Data Acquisition) WAMS (Wide-Area Measurement System) • Update rate: each 2-5 seconds • No time synchronization • Regular communication links • Allows stead-steaty system monitoring • Update rate: 30-60 phasors per second • Time synchronized data • High-speed communication links • Allows the dynamic system monitoring
How can the power system be seen? By SCADA By WAMS
Basic Phasor Measurement Process Idea Sine Wave Window Size (points) Regular sampling period (Ts) Sampling rate Sampling period For N=12
Basic Phasor Measurement Process Idea Time Domain Frequency Domain DFT Samples where
Phasor Estimation Fundamental frequency component, set m=1 • Definition of DFT • Discrete Fourier Transform is a simple widely used method for phasor estimation • Other methods have been discussed • Kalman filters, weighted least squares and neural networks • Currently used in the commercial PMUs
Basic Phasor Measurement Architectures Frequency Tracking Frequency Compensation
Basic Phasor Estimation Architecture • Composed basically by • Analogic and digital filters • Phasor Estimation Methodology • Frequency Estimation Methodology • The most explored and applied is the frequency compensation architecture • Basically because use uniform sampling period
Frequency Estimation (Methodologies) • Frequency Estimation is a key role in the both architectures • Changing the sampling window • Providing the frequency for phasor correction • Several methods are found in the literature • Zero Crossing • Least Error Squares • Kalman Filters • Demodulation • Phasor measurement angle changing
Pos-Processing(Off-nominal Frequency) • Under off-nominal operation the phasor measured (Xmes) is different from the true value (Xtrue) • The effect of the off-nominal frequency can be expressed by a P factor. where N - window size w – actual frequency w0 – nominal frequency Phasor correction
Pos-Processing(Off-nominal Frequency) • The P factor is directly influence by N and frequency value • P behavior under frequency variation (N=48)
Phasor Estimation (Discrete Fourier Transform) • Frequency step (off-nominal operation)
Phasor Estimation (Discrete Fourier Transform) • Sequence positive phasor estimation
Brazilian Interconnected Power System - BIPS • Main Characteristics • Capacity of about 100 GW • Predominant hydroelectric generation (about 71 %) • 90000 km of transmission lines, with voltages ranging from 230 kV to 765 kV • The largest powerplant, Itaipu, has 20 generators with a generation capacity of 14 GW, half in 60 Hz and half in 50 Hz • Composed by 5 subsystems
The MedFasee R&D Project • Project started in 2003 • The main goal was to develop the synchronized phasor measurement technology in Brazil and study its applications • It resulted in two prototypes currently installed in Brazil: • LVPMS (Low Voltage Phasor Measurement System). • HVPMS (High Voltage Phasor Measurement System).
Medfasee Project(First Prototype) • Three PMUs were installed in laboratories of three universities in Southern Brazil • The PMUs measure the instantaneous three-phase distribution voltage • The PMUs have a network interface connected to the Internet to send the phasors to the PDC • 60 phasors/s • The PDC is located in the Electrical System Planning Research Laboratory (LabPlan) at UFSC
MedFasee Project – Low VoltagePrototype Installation Details PMU UTFPR PMU e PDC LabPlan – UFSC PMU PUC – RS
Frequency Monitoring (12/01/2005) 15h00min00s e 15h29min59s) a) Frequency Evolution: b) Frequency Spectrum • System frequency oscillation mode ~ 0,02 Hz (period 50s).
Firsts Disturbances Disturbance Southeast / Mid-West (14/03/2005 – 05h05min12s)
MedFasee Low Voltage Phase II - National WAMS • Characteristics • Develop, dissemination and educational use of the WAMS technology • Nine universities participate in the project • Five geographical regions are covered • Internet is used as commutation link
MedFasee LV - Installations • PMU UFSC – Florianópolis, SC • Installation Date: 30/11/2008
MedFasee LV - Installations • PMU UFPA, Belém, PA • Installation Date: 06/11/2008
MedFasee LV - Installations • COPPE/UFRJ, Rio de Janeiro, RJ • Installation Date: 18/12/2008 Phase II -> Conclusion
Hardware: DELL OptiPlex 755 Core 2 Duo 3GHz, 2GB RAM, 2000 GB HD Software: Operation System - GNU/Linux + (RTAI) Oriented Object Modeling (C/C++) MySQL Database Long-term historical database Communication System: Internet (VPN) MedFasee LVPDC Installation - UFSC 33
MedFasee LV– Phase IIINational Wide Area Measurement System • Characteristics • Improve the national system coverage • 14 universities involved • West BIPS monitoring
HVPMS(High Voltage Phasor Measurement System) • The HVPMS resulted from a partnership with Eletrosul, a transmission utility in Southern Brazil • Four PMUs, installed at Ivaiporã, Areia, Campos Novos and Nova Santa Rita 525 kV substations • Voltage and current phasors are sent to the PDC at a rate of 60 data frames per second • It has been monitoring eight transmission line terminals with two transmission lines having PMUs in both terminals
MedFasee Project EletrosulPMUs • Digital Fault Recorder with PMU functionality • 2 RPV 304 + 2 RPV 310 • Standard IEEE C37.118 • Rate 60 phasor/second - 3Ф • Link Ethernet and UDP/IP protocol • Configurable to 10, 12, 15, 20, 30 e 60 phasors/s e positive sequence RPV 304 RPV 310
Projeto MedFaseeEletrosulPDC • Characteristics: • PC architecture • GNU/Linux + (RTAI) operational system • Object Oriented Modeling (C/C++) • MySQL Database • Features: • Receiving, handling and re-synchronization of phasors • Centralized data available and storage • Support for off-line analysis • 15 days historical database Hardware: • Core 2 Duo 3GHz • 2 GB RAM • 250 GB HD
Data Correlation(LVPMS X HVPMS) • An event, on March 21, 2009, is used to illustrate the correlation between the LVPMS and the HVPMS • Event Description • 525 kV transmission line Lajeado-Miracema tripped; • 900 MW generator shedding at Lajeado hydroelectric power plant;
LVPMS x HVPMS(Frequency Behavior) LVPMS HVPMS High correlation between the recorded data
LVPMS x HVPMS(Angle Difference and Power Flow) LVPMS Angular Difference UFSC (South) – USPSC (Southeast) HVPMS Power Flow TL Ivaiporã-Areia Frequency Spectrum Ivaiporã is an Interconnection point between Southern and Southeastern regions
BIPS Blackout(November 10, 2009) • At 10:13:06 (PM), local time, the three 765 kV (AC) transmission lines that connect ITAIPU power plant to the BIPS tripped • The fault was caused by a sequence of three single-phase short-circuits in different phases, near Itaberá substation
BIPS Blackout(November 10, 2009) • Itaipu real time operation • The Itaipu power plant was operating with 18 generators, with a 5560 MW power flow over the AC link and a 5329 MW power flow over the HVDC transmission system
BIPS Blackout(November 10, 2009) • Sequence and consequences of the Blackout • Disconnection of the Itaipu AC transmission system • Overloading and tripping of transmission lines interconnecting the Southern and Southeastern subsystems • After two seconds, a cascating outage of power plants and transmission lines in the Southeastern region led to a voltage collapse and the tripping of the HVDC link • The disturbance spread to other parts of the BIPS • The blackout resulted in the interruption of approximately 25 GW, 40% of BIPS total load
BIPS Blackout(November 10, 2009) • Recorded by the LVPMS • Voltage dipping, following the outage of the Itaipu AC transmission system and the South-Southeastern interconnections. The voltages recover in the South (PUCRS, UFSC and UTFPR) VoltageCollapse Southeastern subsystem USP-SC, COPPE and UNIFEI
BIPS Blackout(Recorded by the LVPMS) Frequency excursions after the outage of the main South-Southeast interconnection HVPMS – Active Power Flow The 525 kV transmission line (Assis–Araraquara) keeps the Southern and Southeastern regions connected for 1min20s Voltage
BIPS Blackout(Recorded by the LVPMS ) • Asynchronous operation 63.6 Hz (Max) South 58.6 Hz (Min) North LVPMS – Zoom in asynchronous operation
BIPS Blackout(Recorded by the LVPMS) • First South-Southeast reconnection • At 01:43:50 (AM), the first attempt to reclose de interconnection Frequency Spectrum – North-South Mode Frequency
BIPS Blackout(November 10, 2009) • The data captured by the both systems were very important to elucidate the Brazilian Blackout • Since than, the National System Operator have been use the Medfasee data to post-mortem disturbance analysis • Decrease the time spend in post-mortem analysis
Selected Applications • Low-frequency oscillation mode detection • Model Validation • Transmission Line Parameters Calculation • Small-signal control