Online quantization evaluation method of transient state stability of power grid based on WAMS (wide area measurement system) and unit pair

The invention provides an online practical quantization evaluation method of transient state stability of a power grid based on a WAMS (wide area measurement system) and a unit pair and belongs to the technical fields of online monitoring and early warning safety and stability of the power grid based on the WAMS. The method comprises the steps of: screening a generator set omega of which the power grid is distributed most severely relatively based on the wide-area measurement information of the WAMS, wherein setting any two generators within omega equivalent to a stand-alone system; and constructing a dynamic relative transient stability margin index (DTSI) on the basis, wherein the DTSI of the smallest unit pair is taken as the DTSI of the power grid. According to the invention, response track information is actually measured based on the power grid, and a dynamic relative idea is adopted. The method is suitable for any complicated model or transition mode of the power grid; the information can be effectively measured by fully utilizing a PMU (power management unit); the problems of coherent generator identification, curve fitting and energy integral hypothesis path and the like are avoided, and the method is less in calculated amount and high in reliability, and is expected to be applied to online safety monitoring and early warning engineering of the power grid based on the WAMS.