基于Nyquist阵列理论的风电并网系统小扰动稳定分析及控制

Power System Small Signal Stability Analysis and Control Based on Nyquist Array Theory

近年来,新能源、直流等电力电子设备的大量接入,电力系统的小扰动稳定特性发生了显著变化。该文将多变量频域分析理论中的Nyquist阵列理论引入电力系统小扰动稳定的分析及控制。以双馈风电并网系统为研究对象,推导系统中的前向传递函数矩阵Q(s)和反馈增益传递函数矩阵F,基于Nyquist阵列理论对系统的对角优势特性进行判别。针对对角优势系统,绘制其Gershgorin带,可以直观地显示系统稳定特性;针对非对角优势系统,进一步通过伪对角化将系统转化为对角优势系统后再进行稳定分析及控制。最后通过与特征根计算结果的对比,验证所提出方法的有效性。该文所提出方法亦可用于各类电力电子设备的详细模型下电力系统次同步、超同步等宽频带振荡现象的分析。

The dynamic characteristics of the power system have been greatly influenced as the grid-integration of large-scale power electronic devices, such as renewable power generation and direct current transmission. The dynamic stability problem in the wide frequency range is prone to occur. In this paper, the Nyquist array theory in multivariate frequency domain analysis theory was introduced into the power system wide-frequency oscillation analysis and control. Taking the doubly-fed wind power grid-connected system as the research object, the forward transfer function matrix Q(s) and the feedback gain transfer function matrix F of the system were derived. Based on the Nyquist array theory, the diagonal superiority characteristics of the system are discriminated. For the diagonal advantage system, the Gershgorin band can be drawn to visually display the stability characteristics of the system. For the non-diagonal advantage system, the system needs to be transformed into a diagonal advantage system by pseudo-diagonalization, and the stability analysis and control can be performed as the diagonal advantage system. Finally, the effectiveness of the proposed method is verified by comparison with the eigenvalue calculation results. The proposed method can also be used to analyze the sub-synchronous and super-synchronous frequency oscillation brought about by multiple kinds of electronic devices.