A Practical Power System Small Signal Stability Region Using Boundary Defined by Damping Level

A method to define power system small signal stability region(P-SSSR) suitable for the analysis on low-frequency oscillation(LFO) and sub-synchronous oscillation(SSO) is proposed.According to the features of LFO and SSO,a new small stability boundary is defined by relative damping level and absolute damping level respectively,and the P-SSSR is constructed by the new stability boundary.A method to solve the boundary of stability region,in which the continuous method is combined with direct method,is put forward.The boundaries for traditional SSSR and P-SSSR of IEEE first benchmark system are computed,and comparisons of the computing time and boundary characteristics are made between the two stability regions.The results show that in the proposed P-SSSR the requirements for damping level for actual operation are considered,so it makes the operating point located in the P-SSSR conforming to the damping standard in practical operation,and a more reliable and practical small signal stability region can be obtained while the calculation burden is hardly increased.