参数识别纵联差动保护应用中输电线路模型适用频带研究

摘要

In the research of relay protection, transmission lines are usually imitated with different mathematical models. But the mathematical model corresponds with actual physical model approximately only when it is applied in the special frequency band. So it has to consider the suitable frequency band when implementing the relay protection. This paper raises the definition of suitable frequency band of line model applied to pilot differential protection based on parameter identification. And it researches the suitable frequency band of transmission line Π model. It appears that the suitable frequency band becomes narrower with the increase of the length of transmission line, and is irrelevant with the system impedance. Finally, simulations by ATP basically establish the suitable frequency bands of Π model for the transmission lines of different length, provides the criteria for the design of digital filters of pilot differential protection based on parameter identification. And it verifies that the suitable frequency bands have decisive effect on the selectivity and rapidity of relay protection.%在继电保护研究中,输电线路通常采用不同的数学模型进行模拟,而数学模型仅仅在一定的适用频带范围内与实际物理模型近似一致,因此实现保护原理时必须考虑模型的适用频带.给出了适用于基于参数识别的纵联差动保护的线路模型适用频带定义,研究了输电线路Π模型的适用频带.研究表明,输电线路Π模型适用频带随着输电线路长度的增加而变窄,与两侧系统阻抗无关.最后通过ATP仿真研究,初步确定不同线路长度的Π模型适用频带范围,对基于参数识别原理的纵联差动保护数字滤波器设计提供了设计依据,并验证了适用频带对保护选择性和快速性起着决定性作用.