高级检索

分布式发电系统中光伏逆变器低电压穿越技术研究

Research on Low Voltage Ride Through Technology of Photovoltaic Inverters in Distributed Generation Systems

  • 摘要: 在分布式发电系统中,光伏发电的随机性常引起电网频率波动,进而影响光伏逆变器在低电压穿越过程中的动态响应性能,导致逆变器脱网,降低低电压穿越的稳定性。为此,对分布式发电系统中光伏逆变器低电压穿越技术进行研究。首先,在d、q坐标系下建立分布式发电系统并网系统的电压方程,预测并网电流值,并得出并网中的三相电压值。接着,将这些电压分量进行转换,以检测电压跌落情况。然后,根据检测结果和电流内环控制规则,利用稳态阻抗重塑暂态阻抗,给出电流控制信号以控制故障期间光伏逆变器的输出电流。最后,引入空间矢量脉宽调制算法,获取控制器在d、q轴上的控制电压,调控光伏逆变器相关数值以抵消电网电压负序分量,实现低电压穿越。实验结果显示,应用该技术后,在电网出现故障时可及时启动光伏逆变器低电压穿越技术,且在此过程中电网稳定性较高。

     

    Abstract: In distributed generation systems, the randomness of photovoltaic power generation often causes fluctuations in grid frequency, which in turn affects the dynamic response performance of photovoltaic inverters during low voltage ride through, leading to inverter disconnection and reducing the stability of low voltage ride through. Therefore, this article studies the low-voltage ride through technology of photovoltaic inverters in distributed power generation systems. Firstly, establish the voltage equation of the distributed power generation system grid connected system in the d and q coordinate systems, predict the grid connected current value, and obtain the three-phase voltage values in the grid connection. Next, convert these voltage components to detect voltage drops. Based on the detection results and current inner loop control rules, the steady-state impedance is used to reshape the transient impedance, and a current control signal is provided to control the output current of the photovoltaic inverter during the fault period. Finally, the space vector pulse width modulation algorithm is integrated to obtain the control voltage of the controller on the d and q axes, regulate the relevant values of the photovoltaic inverter to offset the negative sequence component of the grid voltage, and achieve low voltage ride through. Experiments were conducted on the above design, and the results showed that after applying this technology, the photovoltaic inverter low voltage ride through technology can be activated in a timely manner when there is a fault in the power grid, and the stability of the power grid is high during this process.

     

/

返回文章
返回