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