Method for selecting low-voltage reactive compensation capacity

The present invention relates to a method for selecting a low-voltage reactive compensation capacity, and the method includes the steps as follows: 1) collecting correlation technical data for a user to install a transformer capacity and a user load report, and collecting power quality background evaluation data of a power supply side and correlation technique data of a power grid; 2) designing the compensation capacity according to collected maximum and minimum system short circuit capacities, an impedance ratio, a nominal voltage, and a correlation budget of the user transformer capacity; 3) and calculating whether a power grid harmonics enlargement exists or not under the capacity based on the designed compensation capacity, and processing with classification according to three conditions. The method avoids the capacity selecting according to the single data regulated by a design discipline and no comprehensive consideration with an actual compensation requirement of the compensated system, and thereby according with the actual requirement and compensating according to the system compensation requirement really.