Determining the most dangerous direction of power system stressing

This paper presents an effective practical approach for identifying the most dangerous direction during power system stressing. To determine the most dangerous direction of system stressing, the value of voltage stability margin should be computed. The most dangerous direction of stressing is the direction along which voltage stability margin is the smallest. Thus, the use of the proposed approach allows us to maximize voltage stability margin. The approach is based on incorporating phase angle variation in steady-state stability criterion for power flow equations, and uses PV-curves and QV-curves together with phase angle variation as one combined voltage stability criterion. Thus, P5-curves and Q5-curves (where 5 is phase angle) are included as a part of voltage stability analysis in addition to PV-curves and QV-curves analyses. The proposed approach includes analysis of surfaces 5(P, Q) and V(P, Q).