基于EEAC理论分析低频振荡

Low-frequency Oscillation Analysis Based on EEAC Theory

扩展等面积准则(EEAC)通过互补群惯量中心—相对运动(CCCOI-RM)变换,将多机系统受扰轨迹映射为一系列时变单机无穷大(TV-OMIB)系统的映象轨迹,并解耦各振荡模式的信息,进而可以识别主导振荡模式,并实现稳定性的量化分析。文中提出以轨迹特征根反映系统非线性对低频振荡特性的影响,以轨迹特征根对各机组机械阻尼系数的灵敏度来反映各机组的参与因子;发现按减小联络线功率的准则调整机组出力可能产生负阻尼效应;指出为抑制低频振荡,应以减小映象功角为准则来调整机组出力。分析扰动大小对系统振荡特性的影响,发现系统振荡特性在分岔点附近可能与平衡点特征根明显不同。

The extended equal-area criterion （EEAC） maps multi-machine system trajectories into a series of time-varying onemachine infinite-bus （TV-OMIB） system trajectories through complementary-clusters center-of-inertia relative-motion （CCCOI- RM） transform. The information of oscillation modes is strictly decoupled. The dominant oscillation mode is identified to implement quantitative analysis for stability. The concepts on trajectory eigenvalue are introduced to reflect the affects of nonlinearity on oscillation characteristics. The sensitivity of trajectory eigenvalue to generator damping is proposed to reflect participating factor of individual generators. It is discovered that adjusting generator power based on the reducing tie-line power criterion may induce negative damping effect. The criterion of adjusting generator based on reducing image power angle will damp low-frequency oscillation. The effect of disturbance under different intension to system oscillation is analyzed. Simulations show that system oscillation characteristic around bifurcation point may be different from the eigenvalue of equilibrium point.