(1) On the distribution network side, there are numerous unbalanced single-phase loads, leading to areas in substation regions. In most areas, the degree of three-phase imbalance varies.
(2) The randomness and uncertainty in the process of using electricity, coupled with the increasing use of high-power loads, has increased the load on single-phase power grids and caused unbalanced three-phase conditions. The imbalance in three-phase variable-frequency power sources can severely impact the distribution network and the user end. This is mainly reflected in the following aspects:
1) Increased power loss due to line resistance, in the four-wire distribution network of three-phase power supply, current flows through the neutral wire, not only on the phase lines but also through the neutral wire during unbalanced three-phase loads, leading to power loss, which increases grid losses. Performance loss; aviation ground power, 36V aviation power supply, 400HZ variable frequency power supply, 115/200V power supply, 27V DC power supply, 400HZ power supply, aviation power supply
2) Increase power loss in distribution transformers. As an important configuration on the low-voltage distribution network side, when powered by single-ended, single-phase power sources, distribution transformers can lead to increased distribution losses.
3) The zero-sequence current generated by the distribution transformer increases with the increase in three-phase imbalance. Due to eddy current losses, the local temperature of the distribution transformer rises, leading to a shorter lifespan of the equipment.
4) It affects the normal operation of electrical appliances, and the three-phase imbalance leads to a decline in power quality, thereby impacting the appliances' performance. Reducing three-phase imbalance can not only stabilize the power quality of the power grid but also decrease power losses in the grid, saving energy.
