Variable speed drives posed challenges in our customer’s office building. Variable speed drives (VSD) are used often in industrial applications, where the use of different process systems requires a constant electric current and different speeds. VSDs have many benefits, however, they are also prone to cause power quality issues. For example, a very common issue is harmonic distortion, which can cause overheating of the components and equipment. Fortunately, something can be done to prevent these problems. In our customer’s office building, the VSDs in the cooling system caused harmonics, but our power quality solutions brought significant improvements.
Challenge in the customer’s office building in a skyscraper
The central district cooling plant at the site has a significant amount of VSD loads. These VSDs are feeding the chillers, compressors, pumps and other loads. The customer reported several issues which are commonly associated with poor power quality, such as burning of electronic cards, excessive heating of transformers and replacement of VSDs.
Knowing that that VSDs create significant harmonic current distortions, a power quality audit was performed initially on one of the several transformers by Distinguished Resources Company (DRC), Merus Power’s local distribution partner. The power quality audit showed that the Total Current Harmonic Distortion (THDi%) at the site were as high as 23%, Such distortion values are clearly higher than allowable limits.
The solution we found for the customer
Based on the measurements, a power quality solution was sized to bring the high current values below the desired limits. Merus™ A2-series Active Harmonic Filter solution built in an IP21 cabinet was shipped from the factory.
Merus Power’s local partner Distinguished Resources Company installed the Merus™ Active Harmonic Filter parallel to the loads in a closed-loop configuration. Active Harmonic Filtering solution was configured during commissioning selectable harmonic mitigation mode to cancel 5th, 7th, 11th and 13th harmonic currents.
Results and customer benefits
- Longer lifetime of electronic cards
- Avoiding overheating of the transformer
- Reduced maintenance costs
- Longer lifetime of plants equipment
- Compliance with the IEEE519-2014
Post commissioning measurements proved that Merus™ Active Harmonic Filter has successfully brought the Total Harmonic Distortion Current (THDi) % under 5%, thus successfully helping to comply with IEEE-519 2014 power quality standards.
All individual harmonics which were exceeding the limits such as 5th, 7th, 11th and 13th were also reduced to a minimum. Successful commissioning and compliance ensured that the electronic cards operate under ideal conditions with sinusoidal waveform, transformer losses are minimized, and overall reliability of the electrical equipment is maintained at desired levels.
Contact us to design solutions that fit your purposes. Our products are modular and easy to scale for very different needs.