Ensuring reliable operation in a water treatment plant

Challenges in the customer’s water treatment plant

A water treatment plant in Galati, Romania was suffering from harmonic currents due to the use of 6-pulse variable frequency drives (VFDs) to control the plant’s processes. VFDs produce an output that is not fully sinusoidal, which can result in high harmonics. Harmonics caused by VFDs can disrupt or stop the operation of sensitive equipment. Measurements revealed that the 5^th and 7^th components produced the most significant harmonic distortion in the plant. The plant suffered from poor power quality and had to fulfill the local harmonic distortion level standards and regulations.

Our Merus^® Solution

The chosen solution was four Merus^® A2 – 200A Active Harmonic Filter modules installed in parallel with the load, which brought the total compensation capacity up to 800 A. The Merus^® A2 modules were installed with help of a local integrator. Merus^® A2-series Active Harmonic Filters have a response time of fewer than 100 microseconds and they can mitigate harmonics up to 50th order, ensuring reliable operation.

Results after installation

After installing and commissioning Merus^® Active Harmonic Filters, harmonics got mitigated to acceptable limits. The lowest THD was achieved by splitting the filtering capacity between the 5^th and the 7^th harmonic component. THD(i) before commissioning the active harmonic filters was approximately 32.6%. After commissioning it was reduced to 4.8%.

The water treatment plant enjoys reduced downtime, lower maintenance costs, energy savings, and longer lifetime of sensitive plant equipment due to improved power quality.