Měřící Energetické Aparáty, a.s.
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Měřící Energetické Aparáty, a.s.
Measurement of voltage quality
in electricity meter
 Technicaly possible
 Price of realisation?
 Interrest of custommers?
 Feasibility is time and financialy demanding
 Contribution for distribution companies?
 Contribution for society?
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Měřící Energetické Aparáty, a.s.
Measurement of energy quantity and quality
 Energy meters are set gauges, measuring functions are stable and consistent
 The meter is perceived by society as an unchanging, certified device and even technically
well-meaning development can lead to discussion and consequently to distrust
 Power Quality Measurement currently goes through a dynamic development
 Implementation in the new networks and
in already constructed and operated networks
 Unification of standards
 Time factor: price + performance ↔ time
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Měřící Energetické Aparáty, a.s.
parameter
quantity measurement
quality measurement
evaluation methods
deterministic
statistic
evaluation period
continuous
10 periods / 1 week
number of values
3 × 6 registers
91 values
measurement
V, I, PF
V, (in future I)
precision requirements
comparable
analog circuits
equal
comm. requirements
comparable
comm. security
required
not for now
computing power /
consumtion
normal
high
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Měřící Energetické Aparáty, a.s.
Questions for decision about joint measurement
of electric energy quantity and quality
 Delivery point for measurement of quality of electric energy is point
in public distribution network, where energy is exchanged between contracting parties.
This point may vary from point of measurement of electric energy quantity
 Class A – for contracting relationships
 Class S – for statistical evaluation (two tendencies of measuring methods)
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Měřící Energetické Aparáty, a.s.
 Linearity range of voltage measurement circuits: 1.75 UNOM
class S – 3rd testing state 1.52UNOM, 20% harmonics, 0.723% flicker, 1% interharmonics
 Evaluation period:
• energy quantity / 15min
• quality / 10min aggregation
 Data transfer security:
• energy quantity / billing
• quality / informative
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Měřící Energetické Aparáty, a.s.
Continuous phenomena
(flagged 10 minute evaluations)
 Frequency evaluation, 10s average value of harmonics basic component
 Flicker evaluation, for changes ∆U/U from 1 change/min. upto 4000 ch./min.
 Voltage unbalance
 Harmonic analysis, frequency of calculation (10 periods/1s, without gaps)
Voltage phenomena
(URMS1 or URMS1/2, hysteresis, clustering algorithms)
 For flagging
 Secured power supply (measurement uncertainity 1% Unom and 20ms during 1 minute)
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Měřící Energetické Aparáty, a.s.
Expected development in votage quality measurement
 Changes of indicative values for voltage and continuous phenomena
 Rapid voltage changes
• Record of RMS values
• Oscilographic record
• Phase angle during inception of rapid change
• Short change of voltage unbalance
• Phase shift caused by rapid change
 Measurement of harmonics and interharmonics (40. H, 50.H, 100.H)
 Transient voltage
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Měřící Energetické Aparáty, a.s.
Conclusions
 Intended association of operational measurements and the measurement
of quantity and quality of el. energy is in place
 The solution can only be assessed on the basis of operational experience
 Verification of measurement in substations which is easily accessible is offering
 It is needed to respect different meanings of measurement in substation
and on interface between distribution and custommer
 Other solutions in case of already constructed and operated networks
and another in new networks or in networks with a refurbished power equipment
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