基于机电扰动传播的大规模电网中频率动态时空分布机理研究

After the interconnected operation of large-area power grids, electromechanical disturbance propagation phenomenon and frequency dynamic temporal- and spatial- distributions become prominent characteristics of dynamic evolution in interconnected power grids, which make the safe and steady operation of grids much more difficult. Moreover, they haven't been analyzed and explained accurately in theory up to now. Hence, it is urgent to carry out the research on coupled electromechanical disturbance propagation and frequency dynamic characteristics in large-scale power grids. This project works mainly aiming at several scientific issues, i.e., propagation characteristics of coupled electromechanical disturbance, principle of disturbance control, frequency dynamic distribution mechanism in large-scale power grids. 1) Considering spatial information of grids, the action-mechanisms of grid structural- and operational-parameters influencing disturbance propagation characteristics are studied by using continuum modeling. 2)Next, presented is the principle of suppressing disturbance propagation by energy storage according to the law of impedance matching in a discrete model. Furthermore, the design schemes and coordinated strategies will be proposed. This project also: 3)expatiates the absorption mechanism of electromechanical disturbance energy and physical essence of energy propagation in a large scope by dispersion phenomenon; 4)and explores in-depth the formation mechanism and influence law of frequency dynamic temporal- and spatial-distribution in power grids, perfects the theory for frequency dynamic analysis, and provides a theoretical basis for the safety operation and stability control of large-scale interconnected power grids. Finally, what must be emphasized more, this project is the further research and exploration aiming at the complicated power grid itself, and focuses on the reveal of intrinsic mechanism and physical phenomena. It has important theoretical significance and practical value to the strategic implementation for national interconnection of power grids in China.

大区域电网互联运行后，机电扰动传播现象和频率动态时空分布成为互联电网动态演变的显著特征，使得电网的安全稳定运行更加困难，至今还无法从理论上进行准确分析和解释。因此，亟待对大规模电网中机电耦合扰动传播和频率动态特性展开研究。项目针对大规模电网中机电耦合扰动传播特性、扰动控制原理和频率动态分布机制等科学问题，考虑电网空间信息，运用连续体建模研究网架结构和运行参数对扰动传播特性的作用机理；提出根据离散模型中阻抗匹配法则通过储能元件抑制扰动传播的基本原理，给出控制器的设计方案和协调运行策略；运用色散现象诠释机电扰动在电网中的消纳机理和能量大范围传播的物理本质；探索频率动态时空分布的形成机理及其影响规律，完善频率动态分析理论，为大规模互联电网的安全运行和稳定控制提供理论依据。本项目是对复杂电网本身的研究和探索，关注机理和物理现象本质的揭示，对我国电网的全国联网战略实施具有重要的理论意义和实用价值。

大规模电网互联运行后，机电扰动在电网中传播引起频率的动态时空演变现象显著，使得电力系统的安全稳定运行更加困难。目前的分析方法无法从理论上对频率时空分布现象进行准确分析和解释，因此，探索频率动态时空分布的形成机理及其影响规律，对大规模互联电网的运行和控制具有重要意义。.本项目针对大规模电网中频率动态分布机理及机电扰动传播特性等科学问题展开，并对风力发电参与电网频率调整后电网频率动态特性的影响进行研究。在扰动传播及频率动态时空变化机理方面：建立了用广义波动方程描述的频率动态时空演变模型，定义频率波的概念用于描述频率动态在电网中的时空分布特性；推导出时空演变模型的色散关系，研究色散关系的物理意义并对其影响因素进行分析；分析了机电扰动在传播过程中在边界处的反射与透射现象，并推导出频率波传播的反射系数和透射系数，分析影响反射、透射的关键因素及其之间的关系；将统计学模型和波动理论相结合，提取了频率动态过程中的行波分量和驻波分量，通过定义指标进行量化分析，根据所提取的时空信息估算频率波的传播速度；分析了直流控制器参数对电网频率的影响，并初步研究了交直流混合运行方式下扰动的传播特性。.在风电调频对电网频率动态特性影响方面：对双馈风力发电机的虚拟惯量控制及变桨距运行方式进行了研究，提出风电机组参与电网一、二次调频的控制策略，根据不同调频状态下系统频率的变化情况，提出了调频渗透率和调频深度的概念；依据风电机组的频率特性曲线，提出双馈风机的二次调频综合控制策略以及风电机组二次调频因子分配策略，实现了风电机组对自动发电控制的主动响应；提出了风速变化情况下的变系数控制方法，使风电机组能够更充分地参与电网的一次频率调整。.本项目从机电扰动传播的角度研究大规模互联电网中的机电扰动传播特性及频率动态的时空分布，对完善互联电网安全运行和稳定控制的相关理论具有重要的科学意义。