直驱风电场经柔直并网的虚拟并联阻抗次同步振荡抑制策略

Virtual Paralleled-impedance Control Strategy of Flexible HVDC Connecting to the PMSG-based Wind Farm for Sub-synchronous Oscillation Suppression

采用V/F控制模式的柔直换流站接纳直驱风电场是典型的电力电子化互联系统,可能存在次同步振荡风险。为探究影响该系统次同步振荡的关键因素,该文基于状态空间建模方法,分别建立了考虑模块化多电平换流器(modular multilevelconverter, MMC)内部动态特性和锁相环(phase-lockedloop,PLL)动态特性的网侧电压源型换流器(grid side voltage source converter,GSVSC)性化数学模型。分析了风电场有功功率和PLL参数对GSVSC导纳矩阵的影响以及有功功率、定交流电压控制器和环流抑制控制器参数对MMC输出阻抗矩阵的影响。基于广义Nyquist稳定性判据,研究了影响系统稳定性的关键因素,提出了在MMC控制系统中加入虚拟并联阻抗的阻尼控制策略,并对控制器的参数选择范围进行了解析计算。最后,电磁暂态仿真模型验证所提策略的有效性以及参数解析的正确性。

It is a typical power electronics-based interconnected system which may have the risk of sub-synchronous oscillation when flexible high voltage direct current(HVDC)station connects to the permanent magnet synchronous motor(PMSM) based wind farm. To explore the key factors affecting the sub-synchronous oscillation, the linearized models of modular multilevel converter(MMC) considering the inner dynamics and grid-side voltage source converter(GSVSC) considering the dynamics of phase-locked loop(PLL) were established based on the state space modeling method. The influence of active power and PLL’s parameters of wind farm on the admittance matrix of GSVSC was analyzed as well as the influence of active power, parameters of constant AC voltage controller and circulating current suppression controller on the output impedance matrix of MMC. The key factors affecting the stability were studied based on the generalized Nyquist stability criterion. A suppression control strategy simulating the performance of paralleled impedance at the points of common coupling(PCC) was proposed. Then, the parameter selecting range of the controller was analytically calculated. Finally, the effectiveness of the proposed strategy and the correctness of the calculated parameters were verified by the electromagnetic transient simulation models.