Měřící Energetické Aparáty, a.s.
www.e-mega.cz
Joint measurement of energy quantity and energy quality
in distribution substations
Měřící Energetické Aparáty, a.s.
www.e-mega.cz
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?
Měřící Energetické Aparáty, a.s.
www.e-mega.cz
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
Měřící Energetické Aparáty, a.s.
www.e-mega.cz
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
Měřící Energetické Aparáty, a.s.
www.e-mega.cz
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)
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
www.e-mega.cz
Měřící Energetické Aparáty, a.s.
www.e-mega.cz
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)
Měřící Energetické Aparáty, a.s.
www.e-mega.cz
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
Měřící Energetické Aparáty, a.s.
www.e-mega.cz
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