基于功率平衡的配电线路节点阻抗在线量测方法

On-line Measurement of Distribution Network Based on Phase -Mode Transformation and Power Balance

智能配电网依托智能电表与采集终端获取实时的信息,通过对数据的挖掘,实现配电网络运行风险的有效控制。当前配电线路参数是假设在三相平衡情况下进行研究,不能精准反映实际配电线路各相参数的情况,而实际配电网络中广泛存在着各相线路参数不平衡的现象,三相线路之间存在电磁耦合,采用传统相分量法对互阻抗难以进行求解,因此,提出一种基于功率平衡的低压线路节点阻抗在线量测方法。该方法依托智能电表采集的线路各节点数据,使用Karrenbauer(卡伦鲍厄)相模变换矩阵,对实际运行线路各节点的三相数据进行解耦,然后依据潮流关系推导基于功率平衡的阻抗参数辨识方程,并利用加权最小二乘法对阻抗参数进行寻优,实现线路各相参数的精准量测。此外,通过分析线路老化与阻抗之间的关系,将阻抗参数作为实时监测线路的老化程度的重要参考依据,结合其他参数对结果进行修正,可实现配电网线路状态的老化异常告警。算例选取了湖南某低压供电线路三相三线电能计量装置2021年1月某日24小时内96组实测数据,输入到量测方法的MATLAB程序,计算得到线路各相自阻抗、互阻抗值,并用反推法进一步验证阻抗结果,计算误差控制在工程允许的-1%~1%内。现场检测和检修验证了测算结果的有效性和可行性。充分考虑到实际配电网络中三相之间存在的电磁耦合现象,通过Karrenbauer相模变换解决了供电线路各相耦合的问题,提高了配电网络运行风险的有效控制能力。

The intelligent distribution network relies on smart meters and acquisition terminals to obtain real-time information.Through data mining,the effective control of distribution network operation risk is realized.The current distribution line parameters are assumed to be studied under the condition of three-phase balance,which cannot accurately reflect the parameter values of each phase of the actual distribution line.However,in the actual distribution network,unbalanced line parameters of each phase in the actual distribution network.There is electromagnetic coupling between three-phase lines,and it is difficult to solve the mutual impedance by using the traditional phase component method.Therefore,an online measurement method of node impedance of low voltage distribution line based on power balance is proposed.This method relies on the data of each node of the line collected by smart meters,and uses Karrenbauer phase mode transformation matrix to decouple the intelligent three-phase data of each node of the actual operation line.Then,according to the power flow relationship,the impedance parameter identification equation based on power balance is deduced,and the weighted least square method is used to optimize the impedance parameters to realize the accurate measurement of each phase parameter of the line.In addition,by analyzing the relationship between line aging and impedance,the impedance parameters are used as an important reference for real-time monitoring of the aging degree of the line,and the results are corrected with other parameters,so as to realize the aging anomaly alarm of the line state of the distribution network.The calculation example selects 96 groups of measured data of a three-phase three-wire electric energy metering device of a low voltage power supply line in Hunan Province within 24 hours on January 2021.The MATLAB program of the measurement method is input to calculate the self-impedance and mutual impedance of each phase of the line,and the impedance results are further verified by the back-stepping method.The calculation error is controlled within-1%~1%of the allowable engineering.Field test and maintenance verify the validity and feasibility of the calculation results.This scheme fully considers the electromagnetic coupling phenomenon between three phases in the actual distribution network,solves the coupling problem of each phase of the power supply line through Karrenbauer phase mode transformation,and improves the effective control ability of the operation risk of the distribution network.