低惯量电力系统宽频机电振荡形态特征解析与智能调控策略研究

After the large-scale new energy is connected to the grid, the inertia of the system is greatly reduced. The electromechanical process of the system, especially the electromechanical oscillation pattern, will change significantly after being disturbed. Therefore, it is necessary to re-examine the electromechanical oscillation of low inertia system and design the corresponding oscillation suppression strategy. In the previous study, the research group found that the frequency of electromechanical oscillation of the system gradually increased when the proportion of wind power increased and the frequency of partial mode was larger than the maximum frequency of the existing electromechanical oscillation（2.5Hz）. In this project, the inertial response characteristics of new energy generation system are studied by combining theoretical analysis with experiment. The inertia of the system under different new energy ratio is quantitatively evaluated and the frequency band of electromechanical oscillation of low inertia system is analyzed. It provides theoretical support for electromechanical oscillation monitoring and suppression. At the same time, aiming at the problem of variable operation mode and parameters of low inertia power system with high proportion of new energy, this paper studies the virtual modeling technology of low inertia power system, which is driven by random data. An on-line extraction and tracking method for the characteristic parameters of electromechanical oscillation is proposed. The quasi-real-time evaluation method for the stability of electromechanical oscillation and the global inertia of the system is explored, and an electromechanical oscillation suppression strategy for wide-area active power modulation and adaptive damping control is established. It provides theoretical basis and technical support to ensure the safe and stable operation of the system after large-scale new energy connecting to the grid, and improving the absorption capacity of the new energy of the system.

大规模新能源并网后，系统惯量大幅降低，受扰后系统机电过程，特别是机电振荡形态将发生显著变化，需要重新审视低惯量系统机电振荡并有针对性的设计振荡抑制策略。课题组在前期研究中发现风电占比增加时，系统机电振荡频率逐渐增加，部分模式频率大于现有机电振荡最高频率（2.5Hz），本项目拟采用理论分析与实验相结合的方式研究新能源发电系统的惯性响应特征，量化评估不同新能源占比情况下系统惯量，解析低惯量系统机电振荡频带，为机电振荡监测及抑制提供理论支撑。同时，针对含高比例新能源的低惯量电力系统运行方式及参数多变的问题，研究随机数据驱动的低惯量电力系统反映射虚拟建模技术，提出机电振荡特征参数的在线提取与跟踪方法，探索机电振荡稳定与系统全局惯量的准实时评估方法，建立广域有功调制与自适应阻尼控制的机电振荡抑制策略，为保证大规模新能源并网后系统安全稳定运行、提高系统新能源消纳能力提供理论依据和技术支撑。

大规模新能源并网后，系统惯量大幅降低，受扰后系统机电过程，特别是机电振荡形态将.发生显著变化，需要重新审视低惯量系统机电振荡并有针对性的设计振荡抑制策略。为此，本项目重点围绕充分挖掘和有效利用互联电网广域量测随机响应数据，及时跟踪系统机电小干扰特征参数，并根据模态参数在线跟踪结果，及时发现系统潜在安全稳定问题，采取有效调控措施，提高系统阻尼水平。主要创新性研究内容包括：. （1）根据随机振动理论推导计算了环境激励下系统随机响应的功率密度谱解析表达式，从数学角度证明了机电振荡特征在电力系统随机响应信号中的存在性，揭示了利用系统随机响应提取系统机电小干扰特征参数的基本机理，为基于随机响应信号的电力系统机电小干扰稳定评估与阻尼调制提供了坚实的数据基础；. （2）以电力系统随机响应信号为数据源，将子空间动态模式分解（Subspace Dynamic Mode Decomposition, Sub-DMD）方法引入电力系统，在线提取系统虚拟状态空间矩阵。通过引入Givens旋转因子，提出了基于递推子空间动态模式分解（Recursive Subspace Dynamic Mode Decomposition, Rsub-DMD）的电力系统虚拟状态矩阵在线递推跟踪方法，从而实现了机电小干扰特征参数的在线提取与跟踪。. （3）针对基于发电机再调度的阻尼提升控制策略中有功调整量在线计算困难的问题，提出了基于区域间功率传输能力在线评估结果的有功调制量确定方法。基于系统随机响应构建互联电网等值两机系统简化模型，在此基础上构建考虑小干扰稳定约束的区域间功率传输能力在线评估优化模型，进而提出了随机数据驱动的小干扰稳定约束下互联电网区域间功率传输能力（Interarea Transfer Capacity, ITC）在线评估方法。. （4）针对现代互联电网规模扩大、运行方式多样以及阻尼调制依据不足的问题，提出了数据驱动的互联电网发电机有功输出参与因子在线计算方法，实现机电小干扰模式与发电机有功功率之间相关性的量化分析，在线精准定位有功调制发电机组，构建了数据驱动的基于发电机有功精准调制的互联电网阻尼调制策略，在线提升互联系统阻尼水平。