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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