功率同步控制的模块化多电平换流器阻抗建模及谐振稳定性分析

为了研究模块化多电平换流器(MMC)采用功率同步控制时的阻抗特性和其接入后系统的宽频谐振稳定性，通过谐波状态空间方法，考虑MMC的内部动态特性和完整的控制回路，建立了MMC采用功率同步控制时的等效阻抗模型。分析了功率同步控制中新引入的功率同步环、无功-电压控制及其他主要控制环节对阻抗特性的影响。研究表明采用功率同步控制的MMC在次同步频段和高频段均可能出现负阻尼效应，因而存在引发谐振不稳定的风险。基于PSCAD/EMTDC进行了阻抗扫描和电磁暂态仿真，其仿真结果分别验证了所建立模型和稳定性分析结果的准确性。

Impedance modeling and resonance stability analysis of modular multilevel converter with power synchronization control

To investigate the impedance characteristics of PSC-MMC(Power Synchronization Control based on Modular Multilevel Converter) and the broadband resonance stability of the system with grid-connected PSC-MMC, utilizing harmonic state space method, considering the internal dynamic characteristics and complete control loops of MMC, an equivalent impedance model of PSC-MMC is built. The effects of newly employed power synchronization loop, reactive-voltage control and other major control loops on impedance characteristics in the power synchronization control are analyzed. The study has identified that PSC-MMC might have negative damping effect in subsynchronous frequency band and high frequency band, so there is a risk of causing resonance instability. Impedance scanning and electromagnetic transient simulation are carried out based on PSCAD/EMTDC, the simulative results respectively verify the accuracy of the model and stability analysis results.