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NxtPhase Corporation Optical Sensors
Benefits • Performance Issues
– Wide dynamic range – from 1 or 2 A to 63kA – Bandwidth from dc to 100th+ harmonic – Accuracy to ANSI class 0.3/IEC class 0.2S – Seismic & vibration performance
• Safety & Environmental Concerns – No oil, cellulose, or SF6 – only nitrogen – No open secondary – No ferroresonance
• Installation Savings & Retrofit Capability – Weight is 10% of conventional device – Voltage & current in one device – Metering & relaying in one device
Line Loading Example
• 765kV line derating due to voltage instability limits. Inaccuracy in measurement has led to line deratings of 100MW
• Example – Line derating of 100MW for a 765kV line – Average price of $30 per MWHr – Peak hours per year: 2000 Hrs – Annual recovery $6 million
Theoretical
Attribute Conventional Bulk Accuracy
Dynamic Range
Bandwidth
Weight
# Devices Required
Installation Costs
Application Flexibility
Earthquake Resistant
Safety Concerns
Environmental Concerns
NxtPhase Competitive Advantage
Business Case • Savings in Substation Capital & Construction Costs
– Fewer units required, lower concern for seismic withstand, reduced costs of: engineering design, real estate, foundation & steel, handling
• Better Operating Performance – Greater revenue capture, improved line loadings, avoidance of
transformer loss estimation, lower risk of explosive failure = safer work environment
• Maintenance & Overhaul Savings - No oil or SF6 gas – Elimination of : field testing, SF6 gas management
• Customer selectable turns ratio – Fewer system spares & savings in inventory management costs
• End-of-Life Disposal Savings - No oil or SF6 gas – No environmental impact
0
20
40
60
80
100
120
140
NxtPhase Optical Current & Voltage Sensors… Capital Savings ~20%, Operational Savings ~90%
0
10
20
30
40
50
60
Capital Savings
Operational Savings
$45
$5
$53
$3 17% 2% 1% 20% $ Saved
(M)
$ Saved (M)
% Saved
% Saved
42%
19%
13% 6% 4% 3% 90%
90%
50%
0%
20%
10%
0% Easier
Upgrade Accuracy Weight Total
Savings
Safety Preventive Maint.
Inventory Accuracy Weight Upgrade Ease
Total Savings
$30
$20
$10 $5 $5
Almost 20% Saved…
Approaching 90% Savings…
Conventional Combined CT
& VT Units
NxtPhase NXVCT
Combined Unit
$60
$130
Cost Savings Example: 230kV CT & VT System for IPP Protection & Metering
NXCT System
NXCT Optical Current Sensor
NEMA Pad
Temperature Sensor
Ground Terminal
NXCT Optical Current Sensor
CT head – may have multiple sets of fiber
Composite Insulator
No gas/oil inside!!!
New Generation NXCT • New “Dry Type” Insulator
– Reduced size, weight & cost – No need for nitrogen fill, pressure monitoring
or associated maintenance compared to our previous design
– No oil or SF6 gas like competing conventional designs
– Insulator length is the only difference between 138, 230, & 345 kV designs – translates to more parts commonality & shorter lead times
New Generation NXCT • New CT Head Design
– Better thermal performance – 3000A rating – Fewer parts for lower cost, ease
of assembly & improved reliability – same design used for NXVCT
– Supports up to two sensors for redundant or extreme dynamic range applications
– Use standard NEMA connection terminals, or...
New Generation NXCT • Bus Mount CT Head Option
– Window CT head with clamps for 4” rigid bus
– Potential to install with no additional footprint
– Eliminate connectors, flex conductors & mounting pedestal to yield installation savings
– No connectors = no chance of heat build up & failure at connection point
New Generation NXCT • “Dual Cable” CT Head Option
– Window CT head has clamps for flexible conductors
– Allows pedestal mount with continuous conductor & no connectors
– Lower cost, higher reliability installation
New Generation NXCT • New fiber optic circuit
– Replaces specialty polarization maintaining fiber with standard single mode fiber
– Customer may specify standard SMF-28 fiber in any cable type desired, commercially available from multiple vendors
– Can be spliced, installed, maintained by any capable fiber optic contractor with standard fiber optic equipment
– Allows complete interchangeability of CT column, electronics, or cable without impacting performance of device
NXVT (with LEA 4V outputs)
NXCT (with LEA 200mV outputs)
Sensor Electronics
NXVT Specs Voltage Classes 115 kV to 500 kV
Metering Accuracy
IEC Class 0.2, IEEE Class 0.3
Protection Accuracy
IEC Class 3P, IEEE Class 0.3
Dynamic Range <2% to >200% of rated voltage
Temperature Range -50°C to +50°C
Bandwidth 0.25Hz to 6 kHz
SNR > 60 dB over 6kHz bandwidth
NXVCT Specs • Rated time delay < 50 µs
• Rated phase delay for metering outputs = 0
• Bandwidth > 6 kHz
• Wake up time (protection NXVCT) = 0
• Continuous thermal current 3000 A
• Other IEC 60044-7 & 60044-8 requirements met
Interface NXCT NXVT
High Energy Analog
1A (metering) 2.5 VA burden
69 V & 115 V 2.5 VA burden
Low Energy Analog
4 V (metering) 0.2 V (protection)
2 kΩ burden
4 V (or other)
2 kΩ burden Digital IEC 60044-8
IEC 61850-9 IEC 60044-8
NXCT Specs Voltage Classes 115 kV to 765 kV
Metering Accuracy IEC Class 0.2S, IEEE Class 0.3
Protection Accuracy IEC Class 5P
Dynamic Range 1 A to 4000 A for metering
Short-time Current 63 kA rms, 176 kA peak
Temperature Range -50°C to +50°C
Bandwidth DC to 6 kHz
Technology
Current Sensing
Circular Polarizer At Top of Column
Mirror Within Head CT Head – can have
Multiple Sets of Fiber Wound Around Head
Linearly Polarized Light to/from Electronics
In the Control Room Composite Insulator
Current Sensing
Faraday Effect
Magnetic field
Incident polarized light
Polarizer
Magnetic field 0
‘stuff’
Optical Detector
Fiber Optic Loop
Light Source
Current Carrying
Conductor
Photo Detector 1
Circular Polarizer
Modulator
Polarizer Mirror
NxtPhase Current Sensor
Interferometric Design
Photo Detector 2
Polarimetric vs Interferometric Sensing
Stray effects shift the signal in relation to the reference, & error is introduced.
NxtPhase Method (Interferometric)
Single linearly polarized light signal
Two circularly polarized light signals in phase with each other.
Alternate Method (Polarimetric)
Phase between signals is shifted in opposite directions due to magnetic field.
Angle (Θ) relative to baseline is shifted.
Stray effects shift both signals in the same direction. Relative phase remains the same, accuracy is maintained.
Input signal Measured Signal Magnetic Field
2Θ
(Baseline) (Measured: Steady) (Measured: Shifted) 2Θ
Θ
Voltage Sensing
Remote opto-electronics
Fiber cable
Multiple electric field sensors
Field-proven, lightweight, composite insulator
Internal shielding moderates surface perturbation effects
Widely separated electrodes
Low pressure dry nitrogen
Electric Field Sensor
Pockels Effect
Electric field
Incident polarized light
Polarizer
Electric field 0
‘stuff’
Optical Detector
Waveplate
NxtPhase Electric Field Sensor Pockels Cell
Single mode of linearly polarized light is coupled into 2 fundamental modes of crystal.
y
x
Elliptically polarized light exits crystal. Power parallel to principle axes of ellipse is measured to determine ellipticity (varies in a linear fashion with the applied electric field).
y
x Quartz ferrule
GRIN lens GRIN lens
Electro-optic crystal
Quartz ferrule waveplate
Polarizing beamsplitter
SMF
Multimode fibers Polarizer
Electric Field
Circularly polarized light is coupled into the electro-optic crystal.
OR
Application History
Hydro Québec 138 kV NXVCT - Metering
Hydro Québec 138 kV NXVCT - Metering
Optical Combined Sensor Conventional
Arizona Public Service 230 kV NXVCT - Metering & Protection
APS’s Deer Valley Substation 230 kV Combined Optical Voltage & Current Sensor
230 kV NXVCT Column
Arizona Public Service
Weight – 180 kg (Conventional – 1100 kg) •Allows install with bucket truck (no crane)
APS’s Deer Valley Substation. 230 kV Combined Optical Voltage & Current Sensor
Arizona Public Service 230 kV NXVCT - Metering & Protection
• Distance line protection • Protection of line using L-PRO relay
– Low Energy Analog (LEA) & conventional signals brought in to relay
– 200 mV current signals – 4V voltage signals – 5A conventional current signals
• Comparison with conventional CTs & VTs using TESLA recorder
• Metering of transformer load
BC Hydro 230 kV NXVCT - Protection
BC Hydro 230 kV NXVCT
Ingledow Substation – 230 kV Combined Optical Voltage & Current Sensor
BC Hydro 230 kV NXVCT
BC Hydro’s Ingledow Substation – 230 kV Combined Optical Voltage & Current Sensor
Northern California Power Authority 230 kV NXCT
American Electric Power 345 kV NXVCT
American Electric Power 345 kV NXVCT
Conventional CT Failure
Conventional CT Failure
Optical CT/VT Interfaces to IEDs
Opto-Electronics Rack 4U, 19”
COMMUNICATION BUS POWER SUPPLY
SENSOR MODULES WITH LEA OUTPUTS
OTHER INTERFACE OPTIONS
Up To 6
HEA – High Energy Analog Outputs (to revenue meters) 120 / 69V, 1A – Metering
(add Amplifiers as necessary)
LEA – Low Energy Analog Outputs (to relays) 4V – Metering / 200mV – Protection (IEEE C37.92)
(always Available)
Merging Unit – Digital Output (to meters/relays) IEC61850-9-1/2 Metering & Protection
F/O
AIS
GIS
Bus/ASC
Sensor Options
Opt
o-el
ectro
nics
NXVCT
X
X
X
X
X
X
X
X
X
X
Vo
TS1 - Current
TS2 - Voltage
Control Room
F/O
10
3
9
8
7
6
5
4
2
1
3 (C)
2 (B)
3 (N)
1 (A)
(N)
3 (C)
2 (B)
1 (A)
2 (N)
1 (N)
Digital Interface O
pto-
elec
troni
cs
V3
V2
V1
I3
I2
I1
MU
MU
LEA/HEA
-”-
-”-
-”-
-”-
-”-
-”-
-”-
-”-
-”-
Future Digital IEC61850-9-1/2
F/O
IED
NXVCT
Connectivity to IED (Meter / Relay)
• Conventional & optical current signals summed inside the L-PRO relay – Optical Low Energy Analog (LEA) 200 mV current signal – Conventional 5A current signals
• Optical Low Energy Analog (LEA) 4V voltage signal brought into L-PRO • All conventional & optical signals monitored using TESLA recorder (Monitoring points indicated by analog, digital. ) • Conventional metering not shown for clarity.
52
52
230kV Line
1 A
200 mV
4 V
NXVCT
LEA Voltage Input
LEA Current Input
Conventional Current Input
Transformer 100/133/167 MVA 230Y/69Y-12.5kV
KD/ KRD
L-PRO
Existing Protection
Arizona Public Service Single Line
Opto-electronics Current Modules
Voltage Modules
Meter
115 V
TESLA
analog
digital
NxtPhase Digital Solution IEC61850-9-1 Serial Unidirectional Multi-drop Point-To-Point Link
Multiple Ports
Ethernet Controller
Merging Unit
Binary Inputs
Synchronization, monitoring, test & configuration interfaces
Ethernet Controller
IED
Ethernet Controller
IED
NXCT
NXVT
FO Links
IEC61850-9-1 (IEC 60044-8) Serial Unidirectional Multi-drop Point-To-Point link
Sampling Rate 80 x fr
Ethernet Controller
Station Controller HMI
EMS/SCADA
Station Bus IEC61850 - Ethernet Hub100Mbps
WAN
(Substation) (Enterprise)
Optical Metering Performance High accuracy wide dynamic range
measurements without loading effects
NxtPhase Optical CTs & VTs with Industry Meters
10 100 1000Secondary Current (mA)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4Sc
ale
Fact
or E
rror
(%)Schlumberger Q1000 Class 2
PML 7600 Class 2
ABB ION Class 20
Landis & Gyr 2510 Class 20
Landis & Gyr 2510 Class 2
Meter Linearity
Typical Configuration
Landis+Gyr MAXsys 2510 Meter Merging Unit
NXCT Opto-Electronics
NxtPhase NXCT Optical Current Sensor
VT
Optical Sensor Advantages
• Conventional instrument transformers leave room for accuracy improvements (especially above Class 0.3%): – Optical CTs & VTs offer system accuracy improvements (today
& in future) – Increased accuracy can yield increased revenue
• NXCT system offers: – Accurate measurement with same NXCT as load grows – Preservation of CAPEX
• Improves asset management – Improved overall accuracy of metering system
Optical Sensor Advantages • Phase & Ratio error
– Must be known at burden levels that transformers in meter system actually see
– Wiring losses must also be included
• Optical sensors provide consistently rated accuracy over dynamic range – Benefits all readings – Also benefits Watt & VAR pulses
• NXVT & NXCT ratio & phase accuracy – Consistently maintained within rated dynamic ranges
Instrument Transformer Errors
Conventional CT vs. NXCT 300 Amp 69KV Transformer Ratio Error
-0.1
-0.05
0
0.05
0.1
Test Current (Amps)
% R
atio
Err
or
Conventional CT
NXCT
300 Amp 69KV Phase Error
-4 -2 0 2 4 6 8
10 12
0.25 0.5 1 1.25 2 2.5 5 6 7.5 10
Test Current (Amps)
Phas
e Er
ror
Conventional CT
NXCT
Instrument Transformer Errors
Conventional CT vs. NXCT
System % Registration
98.000
98.200
98.400
98.600
98.800
99.000
99.200
99.400
99.600
99.800
100.000
100.200
100.400
100.600
100.800
101.000
101.200
101.400
101.600
101.800
102.000
15 25 50 100 150 250 400
Load Points
% A
ccur
acy Conventional CT (FL) + Meter
Conventional CT (PF) + Meter
NXCT (PF) + Meter
NXCT (FL) + Meter
CT & Meter Conventional CT vs. NXCT
High Accuracy at Low Currents
NXCT + MAXSys 2510 Revenue Metering System Performance
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
0.01 0.10 1.00 10.00 100.00 1000.00
% of User Selectable Rated Current
Acc
urac
y (%
)
NXCT + MAXSys 2510
IEEE 0.3 Class CT + ANSI C12-10to C12-20 MeterIEC 0.2S Class CT + ANSI C12-10to C12-20 Meter
NXCT combined with the MAXsys 2510 yields unprecedented accuracy & stability over a dynamic range extending from <0.1% to 150% of a user selectable rated current.
Increasing Revenue Transmission Line rating: 500MWAverage Loading: 50% to 85%
Totals% of Nominal current (5A) 50% 80% 85%Load (in MegaWatts) 250 400 425% of time at loading 25% 45% 30% 100%
Conventional CT with Class 2 MeterAccuracy of metering system 98.535% 99.575% 99.592%Number of hours per month 180 324 216 720Megawatts measured 246.34 398.30 423.27 1067.90Lost Megawatts per hour 3.66 1.70 1.73 7.10Total Monthly lost MWhours 659.25 550.8 374.544 1584.594Cost per MWhr 100.00$ Total Monthly Lost Revenues 65,925.00$ 55,080.00$ 37,454.40$ 158,459.40$
NXCT with Class 2 MeterAccuracy of metering system 99.973% 99.975% 99.975%Megawatts measured 249.93 399.90 424.89 1074.73Lost Megawatts per hour 0.07 0.10 0.11 0.27Lost Revenue per hour 6.75$ 10.00$ 10.62$ 27.37$ Total Monthly Lost Revenues 1,215.00$ 3,240.00$ 2,295.00$ 6,750.00$
Total additional monthly revenues 151,709.40$ Total additional yearly revenues 1,820,512.80$ *Variables in Blue
Optical Sensor Advantages
$130,000
+ $1,820,000
= $1,690,000
Cost of replacing conventional CTs with high accuracy NXCT instrument transformers at 345 kV Estimated additional yearly revenue from improved meter system accuracy Total Value
