VSG策略下计及逆变器饱和的风电系统的暂态稳定分析方法研究

发布时间：2018-06-02 10:12

本文选题：VSG策略 + 逆变器电流饱和　；参考：《南京理工大学》2017年硕士论文

【摘要】：随着微电网的快速发展,风电作为一种最有效、最经济实现绿色环保的方式得到了国内外重视。在系统总容量一定的情况下,风电渗透率的不断提高使得传统同步发电机占有比例减小,导致系统总的转动惯量和旋转备用容量的减小,从而降低了系统的稳定性。为了解决此问题,专家提出了采用虚拟同步发电机(VSG)控制策略使分布式逆变电源模拟传统同步发电机特性的方法。但是在系统大扰动情况下,采用VSG策略的逆变器与传统同步发电机相似也会出现失稳问题。因此,本文对VSG策略下计及逆变器电流饱和特性的风电系统的暂态稳定性进行研究。首先,论文对逆变器数学模型和VSG控制策略原理进行了研究。建立了逆变器电流饱和数学模型。针对逆变器电流饱和特性,分析了 VSG策略下的逆变器虚拟功角暂态特性。同时建立了基于VSG策略的风电系统网络结构和数学模型,并分析得到了采用VSG策略的逆变器与同步发电机之间存在的物理等效。然后,论文利用传统暂态能量函数方法对VSG策略下计及逆变器饱和特性的风电系统稳定性进行研究。仿真分析了考虑逆变器饱和环节的暂态能量函数分析方法的局限性。针对此局限性,从逆变器电流饱和模型入手,提出了采用反正切函数近似的改进方法,使得传统的暂态能量函数方法能够正确分析VSG策略下计及逆变器饱和特性的风电系统稳定性,并通过单机无穷大系统和三机系统对其进行验证。最后,论文引入了基于SMR技术的改进暂态能量函数方法对传统暂态能量函数分析方法存在的保守性进行改善。研究了 SMR技术原理,并构建了计及逆变器电流饱和的SMR技术改进暂态能量函数。通过单机无穷大系统和三机系统对改进方法进行了验证。仿真结果表明,本文引入的SMR技术改进暂态能量函数方法能够正确获取系统暂态稳定性指标,并且减小了暂态能量函数保守性。
[Abstract]:With the rapid development of microgrid, wind power as the most effective, the most economical way to achieve green environmental protection has been paid attention to at home and abroad. When the total capacity of the system is constant, the increasing of the wind power permeability reduces the proportion of the traditional synchronous generator, which leads to the decrease of the total moment of inertia and the reserve capacity of the system, thus reducing the stability of the system. In order to solve this problem, experts proposed a method to simulate the characteristics of traditional synchronous generators by using VSG-based virtual synchronous generator (VSG) control strategy. However, in the case of large disturbance of the system, the instability of the inverter using VSG strategy is similar to that of the traditional synchronous generator. Therefore, the transient stability of wind power system considering the current saturation characteristics of inverter under VSG strategy is studied in this paper. Firstly, the mathematical model of inverter and the principle of VSG control strategy are studied. The current saturation mathematical model of inverter is established. In view of the current saturation characteristics of the inverter, the transient characteristics of the virtual power angle of the inverter under the VSG strategy are analyzed. At the same time, the network structure and mathematical model of wind power system based on VSG strategy are established, and the physical equivalence between inverter and synchronous generator using VSG strategy is analyzed. Then, the stability of wind power system considering the saturation characteristics of inverter under VSG strategy is studied by using the traditional transient energy function method. The limitation of transient energy function analysis method considering the saturation of inverter is analyzed by simulation. In view of this limitation, starting with the current saturation model of the inverter, an improved method using the inverse tangent function approximation is proposed. The traditional transient energy function method can correctly analyze the stability of wind power system considering the saturation characteristics of inverter under VSG strategy, and it is verified by single machine infinite bus system and three-machine system. Finally, an improved transient energy function method based on SMR technology is introduced to improve the conservatism of traditional transient energy function analysis methods. The principle of SMR technology is studied and the improved transient energy function of SMR technology considering current saturation of inverter is constructed. The improved method is verified by single machine infinite bus system and three machine system. The simulation results show that the improved transient energy function method introduced in this paper can obtain the transient stability index correctly and reduce the conservatism of the transient energy function.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614;TM712

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