基于电压突变量的差动保护同步方法研究

A synchronization method of differential protection based on sudden change of voltage

随着基于无线通道的配网差动保护被引入配电网,需要解决的关键技术之一即是两端故障数据的同步问题。基于保护启动时刻电压突变量的同步方法可以在不增加额外设备的情况下实现数据同步,但对该方法的同步精度和适用范围尚缺乏必要的理论分析和验证。通过叠加原理研究了多相故障情况下基于电压突变量的差动保护同步原理,并进一步分析了故障启动门槛、采样频率、故障初始角、谐波和各侧装置采样时刻不同对同步误差的影响,并进行了相关模拟仿真测试。结果表明,取5%的电压额定值作为启动门槛,采用每周波240点采样,能确保各侧装置在线路多相故障时启动时刻的同步误差小于30°,从而满足配网差动保护的同步要求。

With the introduction of wireless channel-based distribution differential protection into the distribution network,one of the key techniques to be developed is the synchronization of fault data at both ends. The method of synchronization based on the voltage surge at the time of protection activation can achieve data synchronization without adding additional equipment. However, there is a lack of the necessary theoretical analysis and verification of the synchronization accuracy and applicability of this method. In the paper, the synchronization principle of differential protection based on voltage mutation under multiphase fault conditions is studied using the superposition principle. The effects of different fault initiation threshold, sampling frequency, fault initial angle, harmonics and sampling moment of each side device on the synchronization error are further analyzed. A simulation test is carried out through ATP modeling, and the results show that taking 5% of the voltage rating as the starting threshold and using 240 sampling points per wave can ensure that the starting synchronization error of each side device is less than 30°, thus satisfying the synchronization requirement of distribution network differential protection.