Active Load Balancer (ALB) is the ultimate answer to power quality problems caused by waveform distortions, low power factor, voltage variations, voltage fluctuations and load unbalance for a wide range of segments and applications.
They are a high performance, compact, flexible, modular and cost-effective type of active power filters (APF) that provide an instantaneous and effective response to power quality problems in low or high voltage electric power systems.
They enable longer equipment lifetime, higher process reliability, improved power system capacity and stability, and reduced energy losses, complying with most demanding power quality standards and grid codes.
Using single-phase loads on a three-phase electric power system (connected phase-to-phase or phase-to-neutral) results in unbalanced load conditions in the system. Unbalanced load currents result in unbalanced voltages and affect other loads connected at the point of common coupling. Unbalanced load conditions also cause excessive neutral current, resulting in overheating motors and transformers, power losses and lower system efficiencies. Load balancing is necessary to improve the power quality and efficiency of the system.
Properly designed and rated ALB can balance any unbalanced load from the supply system point of view. Any unbalanced load can be converted to a symmetrical three-phase active power load only.
Active Load Balancer (ALB) is using current control to deliver load balancing functionality in 3- and 4- wire systems with their full rated capacity. How this relates to power depends on variables like load power factor. They inject capacitive or inductive negative sequence current that has an opposite phase to the load negative sequence current. As a result, the network sees symmetrical load and phase voltages, and currents are balanced without exchanging active power between the network and the ALB.
Main benefits of ALB can be summarized as:
1. Improve voltage unbalance on the phases and reduce neutral current which increases the safety of the installation and allows sensitive loads to operate.
2. Avoid transformers saturation & overloading.
3. Reduce power losses and voltage drop in neutral conductors.
4. Reduce the oscillating torque in the rotating machines that appears because of load variations in the systems.
5. Avoid electrical equipment overheating and efficiency loss that causes premeture failures.
ALB has few low and high voltage potential applications where their use offers many benefits.
⦿ Arc welding machines: Shielded metal arc, gas tungsten arc, gas metal arc, flux-core arc, submerged arc and electroslag welding.
⦿ Resistance welding machines: Spot, seam, butt, flash, projection and upset welding.
⦿ Single-phase loads not well distributed in a three-phase systemL COmputers, lighting, air conditioners, electric vehicles, etc.
⦿ Railway electrification systems: Trains & trams
⦿ Operation of single-phase arc furnace loads.
⦿ Single-phase generators such as small wind turbines and photovoltaics connected to the distribution network bia single-phase power inverters.