摘要
在光伏并网发电过程中,为了不影响电网的电能质量,逆变器输出并网电流谐波分量应该满足相关的并网标准。文章提出了一种基于阻抗分析的方法,分析了光伏并网逆变器与含背景谐波电网之间的谐波交互影响问题。光伏并网所引起的谐波谐振问题产生的根本原因是逆变器等效输出阻抗和电网等效阻抗在并网公共连接点(POC)处存在阻抗交点,且在交点位置阻抗和值最小,此时并网电流幅值将明显增大,即产生谐波谐振现象。为了分析这一问题,本文建立逆变器的诺顿等效模型,推导逆变器的等效输出阻抗表达式,并基于光伏并网谐波电压、电流的最大限值及谐波谐振条件,分析逆变器等效输出阻抗的合理取值范围。在此基础上,采用PI控制、准PR控制两种不同的控制方法调节逆变器等效输出阻抗,有效的抑制谐波,并避免谐波谐振现象的产生。通过仿真实验,验证了本文方法的有效性。
In order to ensure the quality of electric energy, the current with harmonic component generated from in- verter should meet the requirements of intereonneetion standard. A method based on impedance analysis, which focu- ses on the problem of harmonic interactions between the grid with background harmonic and PV grid-connected invert- ers, is presented in this article. Owning to the intersection between the effective output impedance of inverter and the equivalent grid impedance at the point of connection（ POC）, the amplitude of grid-connected current increases signifi- cantly, which leads to the harmonic resonance phenomenon. This paper not only establishes a Norton equivalent model of inverter but also deduces the expression of the inverter equivalent output impedance, and what＇ s more, analyzes the reasonable value range of the equivalent output impedance of inverter on basis of the maximum limit value of har- monic voltage and current, and also on basis of the conditions of harmonics. Two different kinds of control strategies （ PI and quasi-PR control） are given out in this article to regulate the equivalent output impedance of inverter, which is used to restrain the harmonics effectively. The simulation results have proved the effectiveness of such control meth- ods.
出处
《电测与仪表》
北大核心
2014年第10期70-76,共7页
Electrical Measurement & Instrumentation
基金
长江学者和创新团队发展计划资助(No.IRT1114)
国家电网公司项目<电能质量高级分析关键技术研究与应用>(2012515)
关键词
光伏(PV)并网发电
谐波谐振
逆变器
输出阻抗
建模
grid-connected generation of photovohaic（PV）, harmonic resonance, inverters, output impedance, mod-eling
