Welcome
At Mirus International, we strive to keep you informed of the latest harmonic mitigation applications and solutions. I'd like to welcome you to the the inaugural issue of Harmonic Insights, which is devoted to keeping you up-to-date on leading industry developments in power quality improvement products.
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Regards,
Tony Hoevenaars, P.Eng.
President and CEO
Lineator™ and SOLV™ Case Study: SkyVenture Montreal
(Two indoor skydivers suspended in mid-air by SkyVenture blowers using Lineators.)
The owners of SkyVenture Montreal were building a new dedicated facility for their first Canadian location and were determined to meet their grand opening deadline. Mirus International was brought on board to diagnose and devise a solution to their power quality issues.
To achieve the required wind speeds, their blowers needed to use four (4) 350HP Variable Frequency Drives (VFDs). Using SOLV™, Mirus’ exclusive harmonic analysis software, the consulting engineer ran simulations and found that Lineators™ would decrease the harmonic distortion dramatically and meet IEEE Standard 519 limits for both voltage and current. Using Lineators also offered greater efficiency resulting in a shorter payback period as a result of the energy cost savings.
READ THE CASE STUDY.
Challenges when Designing an Effective Harmonic Mitigation System
To address power system harmonics in many water / wastewater Variable Frequency Drive (VFD) applications, transformer phase shifting strategies are often used. To be effective, transformer phase shifting requires the load on multiple rectifiers be shared relatively equally. However, even when the load on multiple rectifiers is perfectly matched, the transformer phase shifting approach can often fall short of expectations.
Most VFDs incorporate a 3-phase, 6-pulse diode bridge rectifier which generates current harmonics in the 5th, 7th, 11th, 13th, etc. When dual bridge rectifiers are used, and the second bridge rectifier is phase shifted by 30° by applying a phase shifting transformer, a 12-pulse scheme is created. A properly designed 12-pulse scheme will only have residual amounts of 5th and 7th harmonics while harmonics will remain in the 11th, 13th, 23rd and 25th. Theoretically, phase shifting systems are an effective means of harmonic treatment; however, they can perform rather poorly under real world conditions. Tolerances in the manufacturing of the transformer windings, applied voltage imbalances, pre-existing voltage distortion and light loading levels will all have a detrimental effect on the 12-pulse scheme’s ability to cancel harmonic currents, particularly at higher frequencies.
Read the technical article ‘Challenges When Designing an Effective Harmonic Mitigation System for your Variable Frequency Drive’ to learn how the Lineator™ solved the harmonic distortion for a mine tunnel boring machine under real-world conditions with much lower losses.
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