Small Signal Stability Assessment with Online Eigenvalue Identification Based on Wide-area Measurement System

Eigenvalue analysis is an important method of evaluating the small signal stability of power system. Traditionally, it is widely employed off-line and thus the obtained results are only effective for limited operation conditions. With the rapid development of wide-area measurement system or WAMS, system-wide dynamics of large power systems can be synchronously measured and quickly centralized, which presents the potential of online assessment of systems' dynamic characteristics. In this paper, a scheme of online identifying dominant eigenvalues and thus evaluating small signal stability is proposed. Its basic principle lies in that: with appropriately selected responses and sitting of phasor measurement units (PMUs), the dominant eigenvalues can be identified by analyzing the measured post-disturbance dynamics of the system. An improved Prony algorithm is developed to make the identification procedure efficient and thus able to run online. Therefore, the results identified vary with operation conditions and a dynamic view of the small signal stability is available to operators. The scheme is implemented as an advanced function upon the real-time data platform of industrialized WAMS. Both simulation analysis and filed test have verified the effectiveness of the proposed scheme