Deep Data from Optical Sensors

Farnoosh RahmatianNuGrid Power CorpAugust 7, 2018

IEEE PES GM, Portland, OR

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©2018 NuGrid Power Corp

Outline• What is a “deep‐data” sensor?• Optical Voltage/Current Sensors• Value Stack• Impact of function requirements• Data Extraction ‐ examples• Life‐cycle value

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Definition“DEEP‐DATA Sensor”A sensor that has the linearity, accuracy, and bandwidth to provide source data for various filtering/optimization to serve a wide variety of applications with different data requirements.

~ multi‐function sensor

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Value Proposition for V & I Sensors• Voltage and Current Sensors are our “eyes” and “ears” into the power system– Can you see far enough?– Can you hear deep enough?

• To maximize value from the grid, we need to see it and hear it “well”– Accuracy– Dynamic range– Frequency range

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Optical Voltage and Current Sensor Systems

S e n s o r E le c t r o n ic s a n d

M e r g in g U n i t

O p t i o n a l C a b l e M a n a g e m e n t B o x

C a b l in g S y s t e m

O p t i c a l T r a n s f o r m e r s S e c o n d a r y D e v i c e s

( e . g . , m e t e r s a n d r e l a y s )

O p t i c a l a n d /o r E l e c t r i c a l C a b l e s

O p t i c a l a n d / o r E l e c t r i c a l C a b l e s

Schematic of a typical optical sensor systemIEEE Std 1601

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Stacking Values• Importance of stacking up 

values/benefits with shared cost– Serving multiple applications with one measurement system

• Importance of suitable architecture– Expandable and modular– Maintainable (design for maintainability)

• Value of using “deep‐data” sensors– Wide Dynamic range– Wide frequency response– Accuracy and linearity

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0

20

40

60

80

100

120

Benefits Costs

Cost‐Benefits Comparison

App 4 (Transient Recording)

App 3 (Power Quality)

App 2 (Metering)

App 1 (Protection)

Common Infrastructure

Data Optimization and Impact on Sensor Requirements

Definition: “DEEP‐DATA Sensor”A sensor that has the linearity, accuracy, and bandwidth to provide source data for various filtering/optimization to serve a wide variety of applications with different data requirements.

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Deep-Data Sensor

Filter A –Accurate

slow-changing

data

Filter B –Accurate

somewhat dynamic

data

Filter N –High-

bandwidth rapidly-

changing data

App 1SCADA

App 3Revenue Metering

App 2Monitoring

App 4Harmonics

App 6Transient Recording

App 5Impedance Protection

App 7Travelling Wave 

Protection

Example of a “DEEP‐DATA Sensor” system design:

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High-Speed Data Acquisition and

Storage

OVT OCT

Optical VT and/or CT

Signal Processing Electronics

Optical Cables

IEDs (Relays, Meters, Recorders, …)

GPS Clock

Legacy Applications

(using narrowband

data)

Optical Voltage and Current Measurement System (Redundancy Not Shown)

Analog Interface(4V, 100V,

1A, 5A, ...rated)

Digital Interface(IEC 61850-9-2 and

IEC 61869-9)

Wide Bandwidth Analog (<10 V rated) or digital

interface

IEDs (Relays, Meters, Recorders, …)

Wideband Applications Development

Pilot Application 1

Pilot Application n

Wideband Output }

* D. F. Peelo, F. Rahmatian, M. Nagpal, and D. Sydor, “Real-time Monitoring and Capture of PowerSystem Transients,” CIGRE General Session 44, Aug. 26 - 31, 2012, paper B3-101.

Function Requirements – Impact on Sensor Requirements

Linearity Example:• Capacitor bank unbalance protection 

– Detect 0.25 to 5 A in a few seconds• Situational awareness

– 50 A to 4000 A in every second• Over current protection

– 2000 A to 100,000A in a few milliseconds

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Function Requirements – Impact on Sensor Requirements

Bandwidth Examples:• Synchrophasors and traditional over current protection

– 50 or 60 Hz components, every cycle or so, 1% to 10% accuracy• Power quality metering to 50th Harmonic (3 kHz)

– 5% accuracy, 50 A to 2000 A primary, every 6 to 10 cycles• HVDC or Static VAR Compensators

– 20 kHz to 100 kHz bandwidth, < 10 µs latency for control• Fast transient recording

– >1 MHz bandwidth, niche application, special sensors and wiring

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Time vs. Frequency Domain11

Time vs Frequency Domain12

Switching & Transients13

IEEE Std C37.241-2017 - Guide for Application of Optical Instrument Transformers for Protective Relaying

SVC Substation Harmonics Measurement

550 kV class testing for harmonics

(Bandwidth 20 kHz)0

0.2

0.4

0.6

0.8

1

1.2

1.4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Harmonic #

% o

f Fun

dam

enta

l Fre

quen

cy Phase C

Phase B

Phase A

©2018 NuGrid Power Corp

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High‐Frequency MeasurementsImpulse and fast transient voltage and current measurements, e.g., for reactive switching test (in laboratory and on site)

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

-4.E-06 -2.E-06 0.E+00 2.E-06 4.E-06 6.E-06 8.E-06

Opt

ical

CT

Out

put V

olta

ge (V

)

Time (s)

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

-4.E-07 -2.E-07 0.E+00 2.E-07 4.E-07 6.E-07 8.E-07 1.E-06

Dete

ctor

Out

put V

olta

ge (V

)

Time (s)

Sample Current Measurement Waveform: 26 kA peak at

0.7 MHz

Sample Voltage Measurement Waveform: 283 kV peak with <100 ns rise-time

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-15

-12

-9

-6

-3

0

3

6

9

12

15

-0.01 0.00 0.01 0.02 0.03 0.04 0.05 0.06Time (s)

Cur

rent

and

Ene

rgy

-250

-200

-150

-100

-50

0

50

100

150

200

250

MO

V Vo

ltage

(kV)

NXVCT MOV Energy (MJ) NXCT MOV Current (kA)NXCT Fault Current (kA) NXVT MOV Voltage (kV)

-15

-12

-9

-6

-3

0

3

6

9

12

15

0.14 0.15 0.16 0.17 0.18 0.19 0.20 0.21Time (s)

MO

V C

urre

nt a

nd E

nerg

y

-250

-200

-150

-100

-50

0

50

100

150

200

250

MO

V Vo

ltage

(kV)

NXVCT-2 MOV Energy (MJ)NXCT-2 MOV Current (kA)NXVT MOV Voltage (kV)

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35Time (s)

Cur

rent

(kA

)

Secondary Arc CurrentUnits

Fault number 1 2 3 4 5Primary arcing time ms 36 36 36 36 42Secondary arcing time ms 425 863 606 290 276Number of voltage peaks clipped by MOV 1 3 3 2 5MOV energy absorbed MJ 2.39 10.7 10.2 3.42 13.6MOV Voltage Peak (absolute value) kV 196 204 204 202 205MOV Current Peak (absolute value) kA 6.4 12 12 12.8 13Approx. MOV Voltage ringing frequency Hz 610 610 620 620 620Primary Fault Current Peak (absolute value) kA 11 11 11 11 11Approximate secondary fault current (peak-to-peak) A 120 160 120 160 160

Summary Results

Series Capacitor Staged Fault Testing

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Shunt Capacitor Banks

-0.01 0 0.01 0.02Time (s)

Mea

sure

d Si

gnal

s (A

rb. u

nit)

UnfilteredFiltered

Showing Primary

Current of 0.5 A

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Staged Approach to Extracting Value• Pick technologies that have wide‐scale use to maximize 

value • Expect (and plan for) progression in use‐cases• Target high‐value applications first, while

– Architecting for application expansion (without blocking future foreseen applications)

– Modularizing system components to allow evolution of modules (to minimize future cost)

• Deployment  in stages– Allow for changing electronics while keeping passive long‐life optics/high‐voltage parts

– Consider life‐cycle cost (not just product cost)

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Questions

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