新型负荷特性对互联电网低频振荡的影响机理研究

With the growth of the power system, its security and stability is exposed to the risk of the low frequency oscillation. As the main components of the interconnected power system, the load and its characteristic plays an important role in the low-frequency oscillation. Now days, the large-capacity and high-density impact properties are appeared in the girds with high proportion of electrolytic aluminum and ferrosilicon. Besides of this, the generalized loads which contain the distributed generation show the characteristics of power random disturbance. In fact, these unordinary loads are proved to have big influences on the low-frequency oscillation with different mechanisms. In addition to the traditional negative damping low frequency oscillation, the forced power oscillation is also need to be pay great attention to. Based on the huge amount of measured data, a large-capacity and high-density impact load characteristics model will be established. Then the mechanism of the influence from these loads will be studied thoroughly. The oscillation is accompanied with the transformation and conduction of energy. There are some significant differences in the mechanisms of energy conversion between the forced oscillation and the free oscillation. The oscillation energy conduction mechanisms among the source, network and load will be studied based on the energy flow method. From the point view of the energy, the mechanism of the load playing roles on the oscillation will be revealed. The results of this research will be helpful in understanding the influence mechanism of load characteristics on the low frequency oscillation in modern power system.

随着现代电网互联规模的不断增大，低频振荡已成为严重威胁电力系统安全稳定运行的突出问题。负荷作为互联电网的主要元件，是低频振荡的重要参与者，其特性对低频振荡具有重要影响。当前电力负荷呈现出许多新的特性，例如电解铝、硅铁等冲击性负荷在部分电网高比例存在，呈现大容量、高密度功率冲击特性，另外含分布式电源的广义负荷呈现功率随机扰动特性。这些新型负荷特性对互联电网低频振荡存在不同机理的重要影响，除传统的负阻尼低频振荡外，强迫功率振荡问题也需要重视。本项目基于实测数据建立大容量、高密度冲击负荷特性和功率随机扰动广义负荷特性模型，深入研究其对互联电网低频振荡的影响机理。振荡伴随着能量的转化和传导，强迫振荡和自由振荡具有不同的能量转化形式，基于能量流方法研究源-网-荷间的振荡能量传导特性，从振荡能量的角度揭示新型负荷特性在振荡中的作用机理。本项目的研究结果有助于认识负荷特性对互联电网低频振荡的影响机理。

随着现代电网互联规模的不断增大，低频振荡已成为严重威胁电力系统安全稳定运行的突出问题。负荷作为互联电网的主要元件，是低频振荡的重要参与者，其特性对低频振荡具有重要影响。当前电力系统负荷呈现出新的特性，例如电铁牵引负荷大幅阶跃特性，冶炼负荷在部分电网高比例存在，呈现大容量、高密度功率周期性冲击特性，另外含分布式电源的广义负荷呈现功率随机扰动特性。这些新型负荷特性对互联电网低频振荡存在不同机理的重要影响。除传统负阻尼机理外，强迫功率振荡问题亦需要重视。本课题基于海量电网实测数据分析总结牵引负荷、冶炼负荷和含风电广义负荷等新型负荷的扰动特性，建立牵引负荷、冶炼负荷和含风电广义负荷的模型，揭示其对互联电网低频振荡的影响机理。电网振荡伴随着能量的转化和传导，研究了低频振荡过程中的振荡能量分布特性，提出了基于振荡能量识别强相关机组和强相关负荷的方法，并从振荡能量的角度揭示负荷特性在振荡中的作用机理。提出了起振阶段和振荡平稳阶段分析相结合的负阻尼振荡和强迫功率振荡甄别和扰动源定位方法。给出了随机激励作用下，电力系统有界波动域的分析方法。提出了基于变点探测的起振监测技术和基于牵引负荷扰动的电网阻尼在线监测方法。本课题的研究结果有助于认识负荷特性对互联电网低频振荡的影响机理和电网振荡的能量分布特性，提高电网振荡的分析和预警能力。