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

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.