基于信号注入法的电容电流计算方法改进  

Improvement of capacitance and current calculation method based on signal injection method

作　　者：周国俊 陈皓[1] ZHOU Guojun;CHEN Hao(College of Electrical Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学电气工程学院,四川成都610065

出　　处：《中国测试》2025年第1期62-68,96,共8页China Measurement & Test

基　　金：国家自然科学基金面上项目(52177129)。

摘　　要：随着电网容量和密度的增大,系统单相接地时电容电流越来越大,因此准确计算电网电容电流十分必要。该文针对传统信号注入法存在的集中电容模型等效准确性不足、系统自然谐振频率过低、谐振频率搜索时存在偏差且搜索时间过长等问题进行分析与改进。首先,分析传统信号注入法产生的误差,结合中压配电网的频率特性,提出改进的单端口等效模型。然后,人为串联电容,解决谐振频率过低导致的励磁支路分流问题。最后,基于相位比较提出谐振频率的二分搜索法,降低搜索次数。改进的信号注入法计算电网电容误差为9.77%,传统方法误差为27.62%;现场实测电流绝对误差值降低3.65 A,超标率降低40%。改进的信号注入法可以有效降低计算电网电容的误差。With the increase of the capacity and density of the power network,the capacitor current becomes larger and larger when the system is single-phase grounded,so it is necessary to calculate the power network capacitance accurately.The problems of the traditional signal injection method were analyzed and improved,such as the insufficient equivalent accuracy of the concentrated capacitance model,the deviation and long searching time of resonance frequency,and the low natural resonance frequency of the system.Firstly,the error caused by traditional signal injection method was analyzed,and the improved single-port equivalent model was proposed based on the frequency characteristics of medium voltage distribution network.Then artificial series capacitor can solve the problem of excitation branch shunt caused by low resonant frequency.Finally,the binary search method of resonant frequency is proposed based on phase comparison to reduce the search times.The error of the improved signal injection method is 9.77%,and the error of the traditional method is 27.62%.The absolute error of measured current decreased by 3.65 A,and the overstandard rate decreased by 40%.The improved signal injection method can effectively reduce the error of power grid capacitance calculation.

关 键 词：信号注入法 电容电流 单端口等效模型 谐振频率搜索 

分 类 号：TB9[一般工业技术—计量学] TM77[机械工程—测试计量技术及仪器]