论文总字数：24639字

摘 要

我国电力系统正处于高速发展阶段，新能源形式如风电等不断被列入发展计划之中。新能源电场如风电场的建设规模不断加大，导致我国电网结构趋于复杂化，电网内部出现强迫振荡、负阻尼振荡等低频振荡的风险也不断增加，为电网的正常安全运行埋下了隐患。为了解决上述问题，有必要研究新能源的特殊性质带来的电力系统低频振荡，并采取措施进行抑制。因此，本文研究分析了电力系统强迫振荡产生机理，探究风电场引发强迫振荡原因，并采用静止同步补偿器及附加阻尼控制器，对风电场引发的强迫振荡进行抑制。

首先本文根据参考文献，对风速进行了数学模型的推导和建立，分析了风力机3p转矩的等值风速模型，对风切变效应和塔影效应的影响进行了数学处理。同时，建立了双馈异步风力机数学模型，并对双馈异步风力机的功率控制进行了研究。

随后，本文研究并分析了周期性波动的扰动源引起强迫振荡的原因、机理、振荡过程和系统振荡的响应结果，以此为基础得出了强迫功率振荡响应的幅值与扰动源幅值、扰动源频率及系统阻尼比之间的关系式。探讨了风机功率对系统内振荡的影响，及风电引发强迫振荡时的特殊性。

之后，本文在Simulink仿真平台上建立了静止同步补偿器的动态控制模型，研究了静止同步补偿器及其附加阻尼控制器抑制系统强迫功率振荡的原理和能力，并在此基础上提出一种利用静止同步补偿器及其附加阻尼控制器抑制系统强迫振荡的控制策略，设计了针对强迫振荡的控制器。

最后，在Simulink仿真平台中的典型四机两区系统中加入使用双馈异步风力机的风电场，以此进行仿真，成功确认了风力机会在电力系统中引发强迫振荡。随后，加入静止同步补偿器及其附加阻尼控制器对该强迫振荡进行抑制。仿真算例表明，该策略能有效抑制风电场引发的强迫振荡。

关键词：双馈异步风机，强迫功率振荡，静止同步补偿器，附加阻尼控制器

Abstract

China's electric power system is in a period of rapid development,and new energy forms such as wind power rise constantly, the scale of wind farm construction continues to increase, resulting in a gradual expansion of China's power grid structure. The possibility of low-frequency oscillations such as forced oscillation and negative damping oscillations in the power grid also increases, posing a hidden danger for the normal safe operation of the power grid. Therefore, it is an important issue to study the low-frequency oscillation of the power system brought by new energy sources. This paper studies and analyzes the mechanism of forced oscillation in power system, finds the cause of forced oscillation caused by the fan, and uses static synchronous compensator and additional damping controller to suppress the forced oscillation induced by the wind farm.

First, the mathematical model of wind speed was established in this paper. Firstly, this paper establishes a mathematical model of wind speed, analyzes the equivalent wind speed model including wind turbine 3p torque, and performs mathematics processing on wind shear effect and tower shadow effect. Then, the mathematical model of the doubly-fed induction generator was established, and the power control of the doubly-fed induction generator was studied.

Secondly, this paper studies and analyzes the causes, mechanisms, oscillation processes and response results of the system oscillation caused by the periodic fluctuations of the perturbation source. Based on this, the relationship between the amplitude of the forced oscillation response and the amplitude of the disturbance source, the frequency of the disturbance source and the system damping ratio is obtained.

Thirdly, this paper establishes the dynamic control model of STATCOM on Simulink simulation platform, and studies the principle and ability of static synchronous compensator and its additional damping controller to suppress forced oscillation of the system. Based on this, a control strategy for suppressing the forced oscillation of the system by using the STATCOM and its additional damping controller is proposed, and a controller for suppressing the forced oscillation is designed.

Finally, a wind farm using doubly-fed induction generators is added to a typical four-machine two-zone system in the Simulink simulation platform to simulate the wind turbine and successfully confirm that the wind power will cause forced oscillation in the power system. Subsequently, the static synchronous compensator and its additional damping controller are added to suppress this forced oscillation. The simulation example shows that this strategy can effectively suppress the forced oscillation induced by the wind farm.

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