| 引用本文: | 刘桂花,马田源,石桐,王卫.双谐波注入的弱电网阻抗在线检测方法[J].哈尔滨工业大学学报,2016,48(9):132.DOI:10.11918/j.issn.0367-6234.2016.09.023 |
| LIU Guihua,MA Tianyuan,SHI Tong,WANG Wei.On linedetection of weak grid impedance with dual harmonic current injection[J].Journal of Harbin Institute of Technology,2016,48(9):132.DOI:10.11918/j.issn.0367-6234.2016.09.023 |
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| 摘要: |
| 弱电网的主要电气特性之一为高电网阻抗，电网阻抗的增大会改变控制系统受控对象的模型阶数，影响逆变器控制环路增益、带宽和控制性能，对光伏逆变器并网电能质量和稳定运行带来不利影响. 为实现电网阻抗的在线检测以进一步优化逆变器控制策略，以弱电网下单相光伏并网逆变器为研究对象，在对其控制系统进行建模与分析基础上，研究基于谐波电流注入的电网阻抗在线检测方法. 首先从理论上对单谐波电流注入法和双谐波电流注入法进行对比分析；进而从仿真角度对两种方法在检测精度、逆变器并网电流THD值影响方面进行验证；最后选定双谐波电流注入法作为主要研究方法，该方法周期性地向电网注入两种不同频率的谐波，利用检测元件获得并网点处的电压和电流信息，经由傅里叶分析处理后可得电参量中所包含的特定次谐波分量，进一步计算可得电网阻抗的实时值. 实验结果表明：双谐波电流注入法可以实现对电网电阻和电感的准确辨识，与传统单谐波注入法相比，该方法不仅无需计算相角信息，同时具有更高的检测精度.
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| 关键词: 弱电网 光伏并网逆变器 双谐波注入法 电网阻抗 在线检测 |
| DOI：10.11918/j.issn.0367-6234.2016.09.023 |
| 分类号:TM46 |
| 文献标识码:A |
| 基金项目:国家自然科学基金(3,3) |
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| On linedetection of weak grid impedance with dual harmonic current injection |
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LIU Guihua, MA Tianyuan, SHI Tong, WANG Wei
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（School of Electrical Engineering and Automation, Harbin Institute of Technology,Harbin 150001,China）
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| Abstract: |
| One of the major electrical characteristics of weak grid is high grid impedance. The high grid impedance can change the order of control object, and influence control loop gain, bandwidth and control performance of PV inverter, which has negative impact on the grid power quality and stability of inverter system. On line impedance detection is beneficial to optimize the inverter control strategy. This paper focuses on the single-phase grid-connected PV inverter under weak grid, study on line impedance detection method with harmonic current injection on the basis of control system modeling and analysis. Firstly, comparing the operation principle of single harmonic injection method and the two harmonic injection method. Then, simulating these two methods in aspects of detection precision and THD value of the grid current. At last, choosing the two harmonic injection method as the major research method. This method injects two kinds of harmonic current with different frequency periodically, then detects the voltage and current of the common coupling point. Through FFT, the specific harmonic and the grid impedance can be calculated. Experimental results show that two harmonic injection method can achieve precise measurement of grid resistance and inductance. Compared with traditional single harmonics current injection method, the proposed method has higher testing accuracy and the phase angle is needless in calculation.
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| Key words: weak grid gird-connected PV inverter dual harmonic current injection grid impedance on line detection |
