Enhanced Flickermeter

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Enhanced Flickermeter

• J. Bruce Neilson, Ph.D. and M. Brent Hughes
• Powertech Labs Inc.
• Vancouver, B.C., Canada

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Measurement Objectives

• Measure voltage flicker seen by customers.
• Assess flicker emission coming from an individual
  customer.
• Assess background flicker coming from other
  customers or the utility.

3
Present Method

• Measure voltage flicker at a customers point of
  common coupling with and without their load
  operating.
• The difference between the two is an estimate of
  that customers contribution to the flicker at
  that location.
• The measurement made without the customers load
  operating is an estimate of the background
  flicker.
• The shortcoming is that the background flicker
  may be different between these two measurements.
  This may lead to an incorrect estimate of the
  customers flicker.

4
Enhanced Measurement

• Measure the customers current as well as
  voltage.
• Estimate the utilitys source impedance and
  voltage.
• Calculate what the voltage would have been for
  the customers load only and a constant utility
  equivalent. This is the flicker the customer is
  responsible for.
• Derive the difference between the measured and
  customers calculated voltage. This is the
  background flicker that the utility and/or other
  customers are responsible for.

5
Flickermeter Implementation

• The basic flickermeter is IEC 868 compliant with
  the 120V adaptation for North America.
• It is implemented in Labview on an NEC portable
  PC with using a National Instruments A/D pc card.
• All calculations are done with cycle-by-cycle
  60Hz vector quantities.

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Circuit Diagram
Utility
Load
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Circuit Diagram
Utility
Measure Vpcc Iload
Pst10pcc
Load
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Circuit Diagram
Utility
Calc. Z ?V/?I
Measure Vpcc Iload
Pst10pcc
Load
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Circuit Diagram
Utility
Calc. Z ?V/?I
Measure Vpcc Iload
Pst10pcc
Calc. Vemission Econst. - Iload Z
Pst10emission
Load
assumed
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Circuit Diagram
Utility
Calc. Vbackground Vpcc Iload Z
Pst10background
Calc. Z ?V/?I
Measure Vpcc Iload
Pst10pcc
Calc. Vemission Econst. - Iload Z
Pst10emission
Load
assumed
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Circuit Diagram
Utility
Calc. Vbackground Vpcc Iload Z
Pst10background
Calc. Z ?V/?I
New Direct Measurements
Measure Vpcc Iload
Pst10pcc
Calc. Vemission Econst. - Iload Z
Pst10emission
Load
assumed
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Wood Chipper
Background
Measured
All flicker caused by customers chipper
Calculated
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Utility Impedance
Plot of V vs. I for a single event known to be
caused by customer
Z ?V / ?I (slope of line)
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Background Motor Start
Background
Measured
Separate external events from customer caused
flicker
Calculated
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Wood Chipper Pst10
More background than customer flicker
Two external motor starts
Chipper 1 start - CT saturates
Chipper 2 start
Measured
Background
Calculated
Chipper idle
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Flicker Countermeasures

• Utility added Dstatcom to counteract voltage
  flicker
• Effect of Dstatcom is incorporated in background
• If Dstatcom current is measured Dstatcom effect
  can be separated from background

Utility
pcc
Dstatcom
Load
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(No Transcript)
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Wood Chipper with Dstatcom
Background Dstatcom
Dstatcom turned on
Measured
Calculated
Voltage dips reduced smoothed
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Dstatcom in Vhold mode
Background Dstatcom
Vhold mode turned on
Measured
Calculated
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Dstatcom in Vhold mode
Background Dstatcom
Vhold setpoint increased
Measured
Dstatcom output limit reached
Calculated
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Wood Chipper Pst10
Background event Remote 230kV fault
Dstatcom turned on measured lt calculated
Calculated
Measured
Background
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Conclusion

• This enhanced flicker measurement technique
  provides a real-time, direct, and simultaneous
  measurement of
• the total flicker at the point-of-common-coupling
• the flicker caused by the customer
• the background flicker already on the utility
  supply
• the flicker improvement provided by
  countermeasures