锁相环同步型变流器并联系统暂态同步稳定分析

Transient Synchronization Stability Analysis of Paralleled Converter Systems With Phase-locked Loop

多锁相环同步型变流器系统在大扰动下易出现暂态同步失稳问题。探究变流器间交互机理及其对暂态同步稳定性的影响是保证多变流器系统遭受大扰动后安全稳定运行的关键。为此,该文以锁相环同步型变流器并联系统为研究对象,通过建立并联系统暂态交互模型,发现变流器间交互作用由互阻抗压降项决定,且主要受注入电流相角的影响。基于此,在计及该交互作用动态特性的基础上,利用等面积定则揭示变流器间暂态交互机理,并量化不同注入电流相角对并联系统暂态同步稳定性的影响。研究结果表明,当互阻抗压降项与自阻抗压降项取值的正负号相反时,变流器并联系统的暂态同步稳定性将得到显著提升。最后,通过PSCAD/EMTDC仿真和RT-LAB半实物实验平台验证了理论分析的正确性。

Multi-converter systems with high penetration of phase-locked loop synchronized converters are prone to have transient synchronization instability under large disturbances. In order to ensure the stable operation of the multi-converter system after large disturbances, it is crucial to study the interaction mechanism between converters on transient synchronization stability of the whole system. To this end, this paper took the paralleled-converter system as an example, and built a transient interaction model. It can be found that the interaction between converters was determined by the mutual-impedance voltage drop, mainly affected by different current injection angles during the fault. On this basis,with considering the dynamic characteristic of the interaction between converters, the interaction mechanism was revealed based on equal area criterion(EAC). The effect of different current injection angles on transient synchronization stability of the system was quantitatively analyzed. The research result shows that transient synchronization stability of the paralleled-converter system can be significantly enhanced when the mutual-impedance and self-impedance voltage drop have opposite signs. Finally, the corresponding model was provided in PSCAD/EMTDC and RT-LAB hardware-in-the-loop experimental platform to verify the correctness of theoretical analysis.