Selective harmonic cancellation to avoid costly downtime in a chemical plant

Challenges in the customer’s chemical plant

Large compressors in an Asian chemical plant were being fed by high-power variable speed drives (VFDs). The operation of the drives was causing power quality challenges, including current harmonic distortions as high as 35 %. The reliable and safe operation of the devices was at risk with such poor-quality performance.

The impact of high harmonic distortions was visible in many areas of the plant. For example in the electricity distribution system with damage to the electronic cards and capacitor banks as well as excessive heating of cables and the transformers. In addition to energy losses and high maintenance costs, the service life of capital equipment was drastically shortened. The 5^th, 7^th, 11^th, and 13^th-order current harmonics were high. Especially the 5^th and 7^th were very high and needed to be immediately mitigated.

Our Merus^® Solution

The customer had several reasons to choose our Merus^® Active Harmonic Filter for cleaning the network from high current harmonic distortions and for restoring the reliability of the production processes. Fast response time and selective harmonic cancellation were some of the key technical requirements established by plant engineers. In addition, with Merus Power’s solution, there was no risk of resonance or overloading.

Selective mode functionality provides great flexibility in choosing the cancellation of selected harmonics. Should harmonics in the other orders increase with the addition of further loads in the future, configuration to another operational mode is simple, just a few clicks away, thanks to Merus^® Active Harmonic Filter’s modern Human machine interface (HMI).

Results after installation

The high values prompted the plant engineers to cancel the 5^th and 7^th harmonics in the selective harmonic cancellation mode. The fast and effective performance of Merus^® Active Harmonic Filters eliminated harmonic distortions in real-time. All individual harmonic distortions levels were reduced below the limits specified in IEEE 519 – 1992, restoring reliable plant operation and avoiding costly downtime. The engineers were particularly satisfied with the selective harmonic mitigation mode and the convenience of easily switching to different operating modes.