基于正规形理论的多馈入交直流输电系统非线性模式分析

传统的特征根分析法不能揭示电力系统的非线性相关作用.正规形理论将非线性系统通过坐标变换,使得原系统与一个线性系统二阶或更高阶等价.将该方法应用到电力系统稳定分析中,既保留了小信号法的优点,又考虑了不同振荡模式间的非线性作用,适用于系统大扰动后的低频振荡特性分析.在对一双馈入交直流并联系统建立动态方程的基础上,运用正规形理论,分析了多馈入交直流系统低频振荡模式的非线性相关作用.结果显示,系统中各种模式是相互影响的,不同运行方式下影响程度也不相同,当系统重载且直流带调制方式下时,区间振荡模式与直流调制模式间的非线性作用最强.时域仿真验证了这一结果.

Nonlinear mode analysis of multi-infeed AC/DC parallel system based on norm form theory

Traditional eigenvalue analysis method can not reveal the nonlinear interaction of power system. However, the norm form theory makes nonlinear system 2-order or n-order equivalent to one linear system through coordinates transform. When used in power system stability analysis,it keeps the advantages of eigenvalue analysis method and oscillatory modes into account,so it is suitable for takes the nonlinear interaction between different low-frequency oscillation study of power system after large disturbance. Based on dynamic equations built for a dual-infeed AC/DC parallel system, the norm form theory is applied to the nonlinear mode interaction of power oscillation. Results show that the interaction exists between different oscillation modes, and its degree changes under different operation conditions. When the system is heavily stressed with DC power modulation, the interaction between area oscillation mode and DC power control mode is the strongest. Simulations validate the conclusion.