MEASUREMENT OF POWER QUALITY PROBLEMS CAUSED BY COMMON LOADS - PQ CASE STUDY

PQ CASE STUDY # 2
Measurement of Power Quality Problems Caused by Common New Loads


1. Introduction
• 2. Theoretical background of power quality and loads
• 3. Description of practical case measurement study
• 4. Results of practical case study
• 4.1 Wood splitter in rural area network
• 4.2 Heat pump in urban area network
• 5. Summary

The use of energy has faced changes during recent years
• Three main issues have driven this change
• Green house effect
• Energy price (which has risen)
• Reduced manufacturing costs of devices
• These issues have brought new devices available to every  consumer
• For example: compact fluorescent lamps, heat pumps,  welding devices, wood splitter etc.

•In this case we decided to  study power quality problems  caused by a wood splitter and  a ground source heat pump
• The decision was made by  power quality complaints  received by a distribution  network company in Finland
• Also the increasing number  of these loads has affected  to decision
•We consider power quality on the basis  of standard EN 50160
•In this study we are focusing on flicker  caused by rapid voltage changes because  it is the biggest reason for power quality  complaints (at least in rural area network)
• Changes in load/device currents produce  voltage changes over network  impedance
• Voltage changes are different depending  on connection of device
• In three phase symmetrical connection all  phases will experience same kind of  change
• In single phase connection all phases will  experience different kind of voltage  change due to star point displacement
• Two things affect to flicker index:  magnitude and repetition frequency of  voltage change.

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