Centralized or Distributed Compensation? How to Place AHF and SVG in Multi-Transformer Facilities

Installing an Active Harmonic Filter (AHF) or Static Var Generator (SVG) requires more than simply choosing current or kVAr ratings. In facilities with multiple transformers or bus sections, physical placement directly determines compensation performance. Deciding between one large centralized unit at the main bus or several smaller distributed units near individual loads depends on your electrical topology, load distribution, and project goals.

AHFs mitigate harmonic distortion from non-linear loads like variable frequency drives and UPS systems, while SVGs dynamically supply reactive power to maintain a power factor near 1.0. Because both systems connect in parallel and rely entirely on Current Transformer (CT) signals for real-time control, placing the measurement point incorrectly will limit compensation results or cause system errors.

Centralized compensation places equipment at the main switchboard near the transformer incomer. This approach works best when the primary objective is satisfying utility requirements for power factor or total harmonic distortion at the main meter. It reduces panel counts, protection devices, and maintenance points while taking advantage of load diversity across downstream branches. However, because harmonic currents still travel through downstream cables before reaching the main bus, branch components continue to experience thermal stress and line losses.

Distributed compensation installs smaller, modular units directly next to major disturbance sources. By eliminating harmonics and reactive power locally, it prevents unwanted currents from circulating through upstream transformers and cables. This method offers high operational independence for facilities with separate production zones, as shutting down one area does not affect compensation elsewhere. The main tradeoffs are increased floor space requirements, additional circuit breakers, and multiple maintenance points.

Facilities with multiple transformers and bus tie breakers require special attention to CT logic. When the tie breaker is open, each transformer operates independently and requires dedicated CT sampling. When the tie breaker closes during bus transfers, current paths change, and improper CT placement or polarity can lead to missing or inverted signals that trip the equipment. Automatic transfer systems should incorporate control interlocking or dual CT switching to maintain accurate measurement under all operating modes.

For most complex facilities, a hybrid strategy offers the best return on investment. Installing distributed AHFs near heavy non-linear loads manages localized harmonics, while a centralized SVG at the main incomer handles plant-wide power factor correction and phase balancing.

YT Electric provides modular AHF and SVG solutions engineered for centralized, distributed, and hybrid topologies. By analyzing your single-line diagrams, harmonic spectra, and operational switching logic rather than relying solely on transformer capacity, YT Electric helps build accurate, reliable, and scalable power-quality systems tailored to your facility.