计及数字控制延时影响的含PMSG电力系统的宽频振荡z域阻抗判据研究

随着大量数字控制被应用于永磁直驱风电机组，受数字控制延时影响，含永磁直驱风电机组电力系统的宽频振荡问题日益突出。为了深入分析宽频振荡失稳机理以及快速准确地评估系统稳定性，提出了一种新的阻抗建模方法和稳定性判据。首先，基于精确离散化方法将含有延时环节的永磁直驱风电机组以及受端交流电网中的系统元件分别建模成锁相环坐标系下的z域阻抗模型。根据电路原理，将所有系统元件聚合成z域聚合阻抗模型，以此作为后续理论发展的模型基础。然后，基于盖尔圆定理，提出广义禁区判据来分析系统稳定性。最后，在Matlab/Simulink中搭建含永磁直驱风电机组的改进IEEE 3机9节点模型验证所提方法的有效性。

The z domain impedance criterion for wide-band oscillation stability analysis of a power system with PMSG considering the impact of digital control delay

There is a large number of digital controls applied in permanent magnet synchronous generators (PMSG). There has been concern about the wide-band oscillation stability influenced by digital control delay in a power system including PMSG. To analyze the mechanism of wide-band oscillation instability deeply and assess system stability rapidly and accurately, both a new impedance modeling method and stability criterion are proposed. First, with the exact discretization method, a PMSG including digital control delay and system components in the receiving-end AC grid are modeled as z-domain impedance in the d-q frame generated by phase-locked loop (PLL). Subsequently, using electric circuit principles, all system components are aggregated into z-domain aggregation impedance. Secondly, based on the Gershgorin Theorem, a generalized forbidden region criterion is proposed to analyze system stability. Finally, a modified IEEE3-machine 9-bus system including PMSG model is built in Matlab/Simulink to verify the effectiveness of the proposed method.