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Synchrophasor: Implementation,Testing & Operational Experience

Doble Engineering Company

Uttam Mishra

Presentation Topics

What is SynchroPhasor

Applications

Testing PMUs

Operational Experience

Conclusion

Phasor Measurement Unit

• Definition : Phasor– Phasor is a vector which has magnitude and angle – Corresponds to a sinusoidal waveform

θ

Phasor Measurement Unit

PMU typical configuration:

Phasor and Synchro Phasor

• Time aligned Phasor : Synchro Phasor• GPS satellites provides time stamp• Time aligning helps to analyze system events

G GZs

21 21

θ θ

Total Vector Error

=

Actual Phasor

Expected Phasor

Error

Ref

1% TVE ≈ .573 degrees (.01 * 360 / 2π)≈ 26.5 μs (at 60 Hz)

Back up applications

• Power system stability• Two ended fault location algorithm• System diagnostics• Distributed Busbar protection• Load shedding• Wide area frequency monitoring

Power Swing Detection

• Protections settings done with known max and/or min operating conditions of power system events

• Actual operation of power system events may not be optimal for the setting of the protection

• PMU provides Phasors in real time• Better decision can be made on load shedding

and system stability• Real time Phasor value helps to fine tune State

estimation

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PMU : Power Swing

• Calculate the angle difference due to disturbance• Apply equal area criteria• Make stability decision • Angle between will vary due to disturbance• Algorithm determines if diverging or settling• Blocking or tripping decision to be made

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G GZs

21 21

θ θ

Distance to Fault

• Single ended fault location algorithm inaccuracy– Fault resistance, load flow & non homogenous system

• PMU enables double ended fault location• PMU data from both end of the line provides very

accurate fault location– Reclose decision can be made for mixed overhead and

cable transmission line– Improved line patrolling :Better productivity & Reliability – Fault location algorithm is based on positive sequence

system parameters

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CFE Network

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Automatic Generation Shedding

• CFE implemented AGSS scheme• CFE has generation in southeast part of the

country while the large load is in the center• If the angle between generation & load bus

exceeds certain value, generation can be tripped• Loss of 400kV transmission capacity can cause

system out of step condition– One line out of service : 70 Phase shift – Both line out of service : 140 Phase shift

• CFE chose 100 to be setting for load shedding

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CFE Network

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Local Phasor

Remote Phasor

ƩThreshold

+-

PU Cyc

0

Trip SelectedGenerators

Europe System Disturbance: November 4, 2006

Grid Islanding

10 GW surplus51.4 Hz

0.8 GW deficit49.7 Hz

8.9 GW deficit49 Hz

Resynchronisation

• A number of uncoordinated unsuccessful attempts made without knowledge of the overall UCTE situation

• Full resynchronisation after 38 minutes

Source: UCTE

UCTE root cause analysis

• Main points:

– (N-1) security rule, inadequate inter-TSO coordination

– Lack of situational awareness

– Other factors (wind farms, lack of coordination)

Improvements since 2006:

Situational awareness• Web-based visibility of cross-border flows in

Europe, • RAAS – real-time awareness and alarming

system

Coordinated (N-1) security analysis• All national files are merged into one common CE

load flow file. • each TSO downloads the complete system and

perform complete (n-1) calculation.

PMU Testing Concepts

Goal: under various conditions, make sure that the reported each PMU data message matches the expected values for each Phasor Vector, Frequency Deviation and ROCOF.

PMU Testing Standard

• Defined in IEEE C37.118.1• Specifies quantities to vary, ranges to vary over,

and required accuracies under different conditions.

• Includes steady state tests, dynamic tests, and transient tests

IEEE C37.118.1 Requirements

• Steady state tests– Frequency– Voltage– Current– Phase (discrete or continuous)– Harmonic Distortion– Out of band interference

• Dynamic tests– Phase and Amplitude Modulation– Phase Modulation– Linear Frequency Ramp

• Transient tests (NYI in Protection Suite)– Magnitude step– Phase step

Setting up a test - Hardware

(PC, F6150 and PMU each have IP addresses)

Protection Suite F6150 : Waveform definitions, start timeProtection Suite PMU : Request config, start transmissionF6150 PMU : Generated waveformsPMU Protection Suite : Config response, phasor data stream

Summary

• Synchrophasors can be put as following in power system protection and control.

Main Protection

Back up Protection

SCADA

PMU’s Protection

msec sec minute Time

Wide Area

Local Area

Local Point

Summary

• PMUs and WAMS enable a new dimension of monitoring power grid operation.

• Synchrophasors solve the problem of time incoherency required for wide-area power system control.

• situational awareness and alarming system will help to avoid unwanted disturbance

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