The utility model relates to a method and a power distribution device which is safe and energy-saving and improves the electric energy quality for a lower voltage distribution grid, namely, a three-phase load unbalance limiting method and a voltage-regulating type three-phase unbalance limiter. The voltage-regulating type three-phase unbalance limiter with the load capacity slightly larger than a branch is characterized by being arranged at the important node position of the load of the low voltage distribution grid. The three-phase load unbalance limiter and the load form a new three-phase power supply system at the node position and generate a new neutral conductor N', so that a zero-sequence current path is limited below the node; and the voltage-regulating type three-phase load unbalance limiter consists of a self-coupled three-phase load unbalance machine or an isolation type three-phase load unbalance machine and a voltage regulating switch. In the utility model, the zero-sequence current which causes the unbalance of a low voltage system is limited under the node of an installed circuit, so that the circuit above the node and a power distribution transformer are balanced in an interphase load, the considerable loss and a plurality of dangers caused by the three-phase unbalance of the part are eliminated, and the safety level of the low voltage distribution grid is improved.