Online Measurements of High-band Grid Impedance Using Variable Frequency Carrier Based PWM Schemes
作者机构：the College of Electrical EngineeringZhejiang UniversityHangzhou 310027China
出 版 物：《CSEE Journal of Power and Energy Systems》 (中国电机工程学会电力与能源系统学报（英文）)
年 卷 期：2021年第7卷第1期
页 面：128-139页
核心收录：
学科分类：080802[工学-电力系统及其自动化] 0808[工学-电气工程] 08[工学]
基 金：国家自然科学基金
主 题：Carrier frequency harmonic impedance measurement voltage-source inverters weak grid
摘 要：Grid-connected power electronic devices, such asvoltage-source inverters (VSIs), are increasingly installed in thegrid for the utilization of renewable energy sources. Under highpenetration, the weak grid contains plentiful harmonics and complexgrid impedance values, which have deep impacts on systemstability as well as its control performance. Online impedancemeasurement is needed for impedance based adaptive controland analysis. This paper proposes a variable carrier frequencyPWM (VCFPWM) based online grid impedance measurementtechnology. This method broadens the available working rangein the high frequency band without increasing the low bandperturbations. Through good analysis and design of the carrierfrequency, the VCFPWM method injects sufficient harmonicenergy at specified high frequency points and guarantees lowTHDs at the same time. The detailed design considerations ofthe carrier frequency are clarified and the characteristics of theVCFPWM based excitations are analyzed in this paper. Finally,the simulation and experimental results based on a three-phasegrid-connected VSI are presented to verify the effectiveness ofthe proposed method.
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