The Hidden Benefits of the SVG Inverter Based Power Factor System - Current Balancing

It is such a common issue -in practical power systems it is nearly impossible to maintain perfect balance or symmetry between phase currents. The diversity of the load such as single phase, non-linear loads like VSD and UPS, and generally imbalanced three phase loads all increase the amount of imbalance in any given system. Trying to spread load evenly across all three phases, for all situations, is nigh on impossible. The result of imbalanced loads is higher neutral currents, transformer and other distribution equipment working inefficiently, and voltage imbalance. The voltage imbalance created can damage other devices or cause items like electric motors, to consume imbalanced currents, exacerbating the original problem.

Many customers that have installed the SVG (and ASVG) inverter based power quality platform are already reaping the benefit of using the current balancing functionality to overcome this issue. Although the SVG and ASVG are primarily installed to improve power factor this additional functionality is proving to be a useful power quality tool.

Standard SVG installation

At the heart of the SVG is the latest in three level IGBT inverter technology. This inverter is normally utilised to provide either reactive currents for power factor correction, or corrective harmonic currents for harmonic correction. When configured to operate in current balancing mode the IGBTs will switch to “exchange” currents between phases at the same time the unit is performing its power factor and harmonic correction role. At this point of operation the SVG is sourcing current from one phase, and manipulating it, in order to supply current to another phase. There is some very fast maths happening inside the brain at this point.

A control drawing showing how the SVG transfers current between phases.

A control drawing showing how the SVG transfers current between phases.

This feature can be enabled when commissioning any SVG or ASVG system. The ability to set the priority of the SVG or ASVG to power factor or current balancing allows the user to ensure the capacity of the system is utilised to meet the customer’s primary requirement.

Many customers have noticed reduced operating temperatures of supply transformers, reduced nuisance tripping of protection equipment, and lower neutral currents after enabling this feature.

Get in touch now to find out more.