Wide rea Monitoring Network Stability & Synchrophasors
New oncept? Hardly. wide area monitoring is an integral part of power system operation today: Telemetry larming and status State estimation What is new? High-speed, reliable & affordable digital communication means overage through broad deployment of IEDs Real-time metering and communication capabilities of modern IEDs ffordable time-synchronized measurements Processing and visualization capabilities Time-synchronized measurements and response time are key 2
ugust 14, 2003 Imagine all operators having access to real-time visualization tools like this. Pre-lackout Ohio Region 115-230 kv Voltage ontour 3
ugust 14, 2003 Real-time tool relying on direct measurements rather than on state estimation Northeast Ohio Voltage ontour at 15:05 EDT 4
ugust 14, 2003 With automated processing and alarming features to identify problems and pinpoint locations Northeast Ohio Voltage ontour at 15:51 EDT 5
ugust 14, 2003 Turned into an automated, or semi-automated closed-loop mitigation system Never-to-be Northeast Ohio Voltage ontour at 16:15 EDT 6
Wide rea Schemes - Drivers Operating the grid is not going to get easier: Insufficient stability margins Generation and load centers displaced even more Environmental and cost constraints on new transmission Deregulations and pressure on asset utilization No recognition for maintaining system security and margins Logical response: With limited capabilities to strengthen generation and transmission (natural stability) need to rely more on active controls (forced stability) etter visualization and assistance tools for operators losed-loop control for events beyond response time of manual control: fight to stay together island controllably restore quickly 7
Is the situation really new? lways true Large systems require monitoring and control capabilities even under good natural margins Margins maintained by a balance between the muscle (generation, transmission) and brain (controls) Somewhat new. Dramatic erosion of natural stability margins dded generation solves one problem but adds new ones Relatively shallow penetration of IEDs and modern communications Downsized engineering force having difficulties catching up with the amount of required upgrades Deregulation and market forces not aligned with best technical solutions Fast-paced society and economy are less forgiving 8
Erosion of natural stability margins Problems are not unique, but the scale is alarming 9
Is the situation really new? lways true Large systems require monitoring and control capabilities even under good natural margins Margins maintained by a balance between the muscle (generation, transmission) and brain (controls) Somewhat new. Dramatic erosion of natural stability margins dded generation solves one problem but adds new ones Relatively shallow penetration of IEDs and modern communications Downsized engineering force having difficulties catching up with the amount of required upgrades Deregulation and market forces not aligned with best technical solutions Fast-paced society and economy are less forgiving 10
pplications Wide rea Monitoring and Warning Systems Telemetry & Inter-utility Data Exchange Load/Generation Shedding ngular Instability Detection Wide-area Voltage Regulation Remedial ction & Power System Protection Schemes System ack-up Protection & Related pplications oordinated Restoration Self Recovering Systems Theoretically-founded opportunities, limited practical experience 11
Wide rea Schemes - Issues Organizational Technical Inception System studies Design: Investment Local measurement Ownership ommunications Deployment Data concentration Testing Redundancy Maintenance Fail-safe and self-monitoring Security of data Data archiving Market viable data pplication: Unpopular manual controls oordination & rming Multi-disciplinary effort Visualization Operator assistance algorithms utomated control algorithms 12
UR N60 Swiss rmy Knife for Special Protection Schemes 13
Local measurements Major measurement points: Status of transmission paths ctive & reactive power Voltages & currents Temperature & wind Synchrophasors and synchronized measurements Principles: Specialized devices vs hardened but general-purpose platforms Redundant devices vs redundant measurement points Flexible and redundant communication capabilities Degree of separation from both SD and asset protection Modern relay platforms are a good choice (N60!) 14
Major areas of functionality System Oriented Features (PS, OST, Open Pole, f, df/dt) Powerful Data cquisition apabilities (V,I,P, o,pf) Powerful ommunication apabilities (GOOSE, Direct I/O) FlexLogic & Simple MTH functions Flexible, Universal, High-density I/O 15
N60 Features Out-of-step tripping Power Swing locking Under- & over-frequency Rate of change of frequency Synchrocheck FlexLogic dp/dt, dv/dt via FlexElements Sensitive Directional Power Open pole detection VT Fuse Failure Overcurrent Under- & over-voltage LEDs, Latching outputs Weather data & actions Peer-to-peer via Ethernet Peer-to-peer via SONET G.704, RS422, 37.94, fiber Flexible comms. architectures Telemetry with 8-bit resolution dd, subtract, compare, select Respond to remote & local data 16
Wide-area Schemes 17
Flexible peer-to-peer communications 18
rchitecture with JMUXes and URs pplications Data oncentrator 19
Synchrophasors The Next Major Step in UR offering 20
oncept and definition fter a major system blackout Imagine a team of reporter photographers with flash cameras dispatched to take a snapshot of the power system state V V V V V V V V V 21
oncept and definition Need an arbitrary angle reference -30 o 0 o 30 o -60 o N 60 o -90 o 90 o -120 o S 120 o -150 o 180 o 150 o 22
oncept and definition fter a major system blackout Imagine a team of reporter photographers with flash cameras dispatched to take a snapshot of the power system state V N V S V V V N N S V V S V V 23
oncept and definition Imagine an automated system with strobe lights synched via GPS and communicating results via digital network V GPS N V S V V V N N S V V S V V GPS lock Modem GPS lock GPS lock Modem Modem Modem 24
Synchrophasors Strobe Light nalogy -30 o 0 o 30 o -60 o N 60 o -90 o 90 o -120 o S 120 o -150 o 180 o 150 o 25
60 o 30 o Strobe Light nalogy 90 o 120 o 150 o 0 o -30 o -60 o -90 o -120 o -150 o 180 o
Phasors Rotating rotors = alternate currents / voltages V N S V V Phasors are well established means of representing ac circuits harles Proteus Steinmetz (1865-1923) omplex Quantities and their use in Electrical Engineering; harles Proteus Steinmetz; Proceedings of the International Electrical ongress, hicago, IL; IEE Proceedings, 1893; pp.33-74. 27
Measuring Synchrophasors 28
Strobe Light nalogy 29
IEEE Synchrophasor Standard (P37.118) Original standard 37.1344 was released in 1995, reaffirmed in 2001 The new standard P37.118 IEEE Standard for Synchrophasors for Power Systems in balloting Strong desire to release it in order to advance the field No IE standard at the moment; most likely the IEEE will become IE (similar to the OMTRDE standard) Key items agreed upon: Time reference = UT (Universal Time oordinated) Measuring rates = (10,25 / sec @ 50Hz; 10,12,15,20,30 / sec @ 60Hz starting at the top of a second) ngle reference = cosine (0 deg at positive waveform peak) ommunication model (standard frames and data types, interoperability) 30