In order to detect the subsynchronous oscillation in power system in time and take measures to ensure the safety of the generator set and stability of power system

by referring to the synchrophasor measuring algorithm principle

the influence of subsynchronous oscillation on the phasor measuring unit(PMU)measurement results is analyzed. In light of the new requirements of synchrophasor measurement proposed by IEEE Std C37. 118—2011

the problems of master stations using synchrophasor data measured by new standard PMU in monitoring subsynchronous oscillation are analyzed. The limitations of analyzing subsynchronous oscillation by master station are pointed out. On the basis of the above

a method of on-line identification and alarm for subsynchronous oscillation on PMU device is proposed

and the feasibility of the method verified by simulation experiments. This work is supported by National Natural Science Foundation of China(No. 61233007)and State Grid Corporation of China.