基于双环路反馈的三相逆变器有源阻尼并网控制策略研究

As an energy exchange interface between the new energy generation unit and the grid, grid-connected inverters were used to convert DC energy into high-quality AC energy and feed it into the grid, which is an important part of the new power system. LCL filter is widely used in the output of the grid-connected inverter because of its excellent ability to suppress high-frequency harmonics. However, due to the lack of damping term in the open-loop transfer function, there is a resonance peak, resulting in unstable operation of the system. In view of these problems, the active damping control using inverter side current was proposed. Compared with the traditional capacitive current active damping control strategy, the fundamental frequency gain T_fo and the cut-off frequency f_c can remain unchanged in the face of the impedance change of the grid. And analysis from the perspective of damping, it has better stability margin and response speed. In order to further reduce the influence of grid voltage on grid-connected current, the grid current proportional feedback was introduced at the same time, to construct a double-loop to increase the output impedance. The inverter current loop was used to eliminate the resonance peak, and the grid current loop was used to reduce the harmonic component. Finally, simulation was performed to verify effectiveness and feasibility of the proposed control strategy.