Method used for identifying area being weak in voltage stability of power grid

The invention relates to a method used for identifying an area being weak in voltage stability of a power grid. On the basis of a traditional modal method, the inaccuracy caused by great influences of active power for Jacobian matrix characteristic values of a system at a power grid running limit state is considered, and a full-voltage modal analysis method with the active power being considered is provided. A weak node acquired according to the method when the stability margin is very small or the system operates at critical destabilization is more accurate. In addition, the method not only can determine the weak node, but also can a control branch and a motor which have a main effect on the current destabilization mode, so that key information is provided for compensation site and load shedding location selection; and valuable engineering guidance information for preventing and controlling voltage destabilization and ensuring safe and stable operations of the power grid. 种用于辨识电网电压稳定性薄弱区域的方法，在传统的模态法的基础上，考虑到在