考虑锁相环角频率变化的单相车网系统动态稳定性分析

Dynamic stability analysis for single-phase vehicle-grid system considering angle frequency variations of phase-locked loop

在高速铁路中,动车组和牵引网之间的参数不匹配可能会导致低频振荡现象发生。虽然常见的阻抗分析法已被广泛用于解释这种现象,但是为了降低计算复杂度,建立了单相车网系统的时域状态空间平均模型。在该模型中,考虑了锁相环的角频率变化和控制中的时间延迟,以更好地反映实际的dq解耦控制。为了避免基于Nyquist曲线或Bode图分析方法在频域中所需的输入输出阻抗的复杂计算,采用根轨迹分析了电路和控制参数对车网系统稳定性的影响。此外,还应用design-oriented分析方法对各种参数的稳定边界进行了绘制。通过比较理论分析、软件仿真和硬件在环实验结果,最终验证了所建立数学模型的准确性和所应用分析方法的有效性。

In high-speed railways,the parameter mismatch between the electric multiple units and the traction network may cause low-frequency oscillation phenomenon.Although the common impedance analysis method has been widely used to explain this phenomenon,but in order to decrease the computational complexity,a time-domain state-space average model of the single-phase vehicle-grid system is established.In this model,the angular frequency variations of the phase-locked loop and time delay are considered in the proposed model to better reflect the actual dq decoupling control.To avoid the complicated calculation of input and output impedance required in the frequency-domain based on the Nyquist curve or the Bode diagram analysis methods,the root locus is adopted to analyze the influences of the circuit and control parameters on the stability of the vehicle-grid system.Further,the design-oriented analysis method is adopted to draw the stability boundary of various parameters.By comparing the results of the theoretical analysis,software simulations and hardware-in-loop experiments,the accuracy of the established mathematical model and the validity of the applied analysis method are verified in the end.