A linear static voltage stability margin for radial distribution systems

A new static voltage stability margin (VSM) of a radial distribution system is proposed to faithfully determine the distance to voltage collapse. The proposed VSM varies almost linearly with system load and it requires only the complex bus voltages to evaluate. By knowing the values of the proposed VSM at two different operating points, the system critical load or distance to voltage collapse can correctly be determined. The effectiveness of the proposed VSM is then tested on two 12.66 kV radial distribution systems consisting of 33 and 69 buses. The critical loads found from the proposed VSM are then compared with the corresponding actual values obtained through repetitive power flow solutions for successively increased load conditions and are found to be in very good agreement.