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.
Typical Applications
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.