ups d9-11 1 optical design options nxt phase
TRANSCRIPT
8/8/2019 UPS D9-11 1 Optical Design Options Nxt Phase
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IEEE PES Substation Committee Annual Meeting
May 1, 2000
Design Options Using Optical
Current and Voltage Transducers ina High Voltage Substation
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Overview of Discussion
• History of NxtPhase origins.
• Basic description of current and voltage sensing
technology.
• Benefits of optical sensing compared to
conventional.
• Example case of using optical sensing
technology.
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The new company has been formed by
combining the industry’s leading teams inoptical current & voltage sensing
Fiber Optic CurrentSensing Technology
Based on Gyros for
Military and AerospaceApplications
Integrated Optic
Pockels Cell for VoltageSensing Technology
A Powerhouse of Technology
30 People located in
Vancouver & Phoenix
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FiberOptic
Loop
LightSource
CurrentCarrying
Conductor
PhotoDetector
CircularPolarizerModulator
Polarizer
Mirror
Fiber Optic Current Sensor
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Electric Field Measurement w ith the
Integrated Optics Pockels Cell
Electric
Field
Linearly polarized light in.
y
x
Elliptically polarized lightout. (proportional to field)
y
x
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8/8/2019 UPS D9-11 1 Optical Design Options Nxt Phase
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Advantages of Optical Sensors
• No CT saturation or VT ferroresonance (magneticcircuit eliminated)
• No insulating oil or SF6required (NxtPhase unique)
• Zero footprint capability
• Voltage and current sensing in one device
• Low weight
• Wide, adjustable dynamic range (NxtPhase unique)
• High bandwidth, limited by electronics• Electrical isolation provided by fibers
• Metering and relaying in one device
• Leads to digital communication and data aquisition
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IPP tap from utility breakers
IPP Metering Example
It is desired to revenue meter (ie 0.3% accuracy):
- outgoing generation
- station service load with no generation
IPP ownedequipment 138 kV
13.8 kV
Stn. Service Xfmr.
475 kW load
Utility owned equipment
Gas TurbineGenerators
225 MVA
13.8 kV, 60 Hz
Design Constraints at 138 kV:
Fault Level = 40 kA
Max. Gen. Current = 3000A
Stn. Service Load = 2A
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Why Existing CTs Will Not Perform Adequately
Conventional CTs do not have revenue accuracy at the low
end of measuring range.
Solution?…Use two CT windings. One low range, one
high range.
No!
Wide dynamic range and high fault currents can cause
grief.
Secondary currents on CT secondary windings must not beallowed to reach levels which may burn out wiring and/or
meters.
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IPP tap from utility breakers
Stn. Service Metering700:5
(140:1)
Ifault = 286A
Istn service = 14 mA
Igen = 21.4 A
Gen. Metering3000:5
(600:1)
Ifault = 67A
Igen = 5A
Limitations of Conventional Technology
Constraints for choosing CT ratio:
Ifault < 300A for 1 cycle
Igen < 15A continuous.Istn service > 5% of Igen
IPP ownedequipment 138 kV
13.8 kV
Stn. Service Xfmr.
475 kW load
Utility owned equipment
Gas TurbineGenerators
225 MVA
13.8 kV, 60 Hz
Design Constraints at 138 kV:
Fault Level = 40 kA
Max. Gen. Current = 3000A
Stn. Service Load = 2A
Stn. service metering cannot be achieved
with conventional CTs due to range andfault levels!
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Yes, but with its own problems.
Multiple metering points could be installed on low side, but:
• Requires utility equipment on customer premises. (may notbe desirable)
Can the Problem be Overcome Using Conventional Technology?
• Metering at generation bus may be more expensive due to:
- isolated phase bus
- high currents at generation bus
- station service load would have to be “split off” fromgeneration when the generators are on to prevent charges to
IPP
• Transformer losses may require estimation.
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Does the problem warrant attention?
Why not estimate the station service load?
• Station service loading consumes energy which has value.
• Estimation of station service load is not accurate.
• Actual measurement will prevent disputes between IPP and utility.
It isn’t much power being used, but it is a load which is always there!
• 475 kVA stn. service (8000 hrs) vs 700 MVA generation (900 hrs)
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Benefits of Metering Using Optical Transducers
• Single metering can be installed at “point of sale”.
-no estimations of loads or losses
-installation on utility premises
• Insensitive to high fault levels.
• Accurate over entire dynamic range.
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IPP tap from utility breakers
Optical Current Sensing Solution
Analogue Meter
(Analogue Metering)
120V analoguesignal
Current Sensor
Voltage Sensor
NXVCT
1A analoguesignal
IPP ownedequipment 138 kV
13.8 kV
Stn. Service Xfmr.
475 kW load
Utility owned equipment
Gas TurbineGenerators
225 MVA
13.8 kV, 60 Hz
Optical CurrentElectronics
DAC,Amplifier
Optical VoltageElectronics
DAC,Amplifier
- 0.2% accuracy over 2 – 3000A range
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Optical Current Sensing Solution
Meter with digitalinput
(Digital Metering)
Current Sensor
Voltage Sensor
NXVCT
Optical CurrentElectronics
Optical VoltageElectronics
IPP ownedequipment 138 kV
13.8 kV
Stn. Service Xfmr.
475 kW load
Utility owned equipment
Gas TurbineGenerators
225 MVA
13.8 kV, 60 Hz
IPP tap from utility breakers
MergingUnit
- 0.2% accuracy over 2 – 3000A range
- Analogue, digital conversions removed
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Optical current sensing can provide cost effective
solutions to metering (and protection) problems thatcannot be easily solved using conventional technology.
Future progress into a complete digital system willprovide additional benefits that will exceed thecapability of analogue systems.
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Questions?
James Hrabliuk, P. Eng.
NxtPhase Corporation
3040 East Broadway
Vancouver BC V5M 1Z4
www.nxtphase.com
604-215-9822 ext 243