多直流馈入受端城市电网直流落点处系统侧谐波阻抗估计方法  

Method for Utility Harmonic Impedance Estimation at DC Terminals of Multi-infeed Urban Power Network

作　　者：舒勤[1] 彭安庆 徐方维[1] 赵劲帅 郑鸿儒 SHU Qin;PENG Anqing;XU Fangwei;ZHAO Jinshuai;ZHENG Hongru(College of Electrical Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学电气工程学院,成都610065

出　　处：《高电压技术》2020年第6期2049-2056,共8页High Voltage Engineering

基　　金：国家自然科学基金(51877141,51842703)。

摘　　要：多直流馈入受端城市电网存在严重谐波振荡与放大问题,为进行合理的谐波管控及治理,需对直流落点系统侧谐波阻抗进行准确估计。为了克服现有方法在该场景下无法准确求解谐波阻抗的不足,提出一种基于谐波阻抗方差最小准则的系统侧谐波阻抗估计方法。首先考虑较短测量周期内,谐波阻抗由于系统运行稳定而变动较缓,具有较小方差的实际特性,提出谐波阻抗方差最小准则;其次采用该准则建立优化方程,并以背景谐波范数对方程进行约束;最后求取满足方差最小准则的系统侧谐波阻抗。仿真实验和实际工程数据结果表明,所提方法削弱了背景谐波及阻抗变动对估计的影响,解决了现有方法在较大背景谐波及两侧阻抗相近时难以准确求解谐波阻抗的难题,在多直流馈入场景下估计误差更低,具有良好的可应用性。There are serious harmonic resonance and amplification in the multi-infeed DC power network of a city,thus the premise of harmonic control and suppression is the estimation of utility harmonic impedance at DC terminals.In order to overcome the shortcomings of the existing methods,a novel method based on the criterion of minimum variance of harmonic impedance is proposed.Firstly,the actual impedance characteristics of small variance and slow change with the stability of power system operation in short sampling subinterval are considered,and the criterion of minimum variance is proposed.Then,the criterion that the impedance in short period has the minimum variance is utilized to establish the optimization function,and the norm of background harmonic is chosen as the constraint of the function.Lastly,the utility impedance which satisfies the criterion can be estimated by solving the function.The simulation cases and actual engineering scenario results indicate the proposed method can be adopted to reduce the influence of background and impedance fluctuations and solve the inaccurate estimation problem in scenario of intensive background and close magnitudes of harmonic impedance.The proposed method has lower estimation errors in multi-infeed DC systems and has reliable applicability.

关 键 词：多直流馈入电网 直流落点 最小方差 谐波阻抗 背景谐波 

分 类 号：TM721.1[电气工程—电力系统及自动化]