Abstract：In the wake of the gradual increase in penetration of distributed power generation systems and the wide distribution of access points, the grid can’t be treated as the ideal sinusoidal voltage source any more. Instead, it contains a large set of grid impedance values, featuring as a weak grid. In this case, the grid-voltage feedforward widely used in grid-connected inverter control will challenge the system stability. Taken the L-filtered grid-connected inverter as an object, the influence mechanism of the feedforward control on the inverter’s characteristics in weak grid is clarified by the equivalent transformations of the control block diagram. Moreover, the effects of the inductance and the resistance-to-inductance ratio of grid impedance on the stability of grid-connected inverter are investigated. Furthermore, a band pass filter (BPF) is incorporated into the feedforward path, to improve the robust stability of the grid-connected inverter in weak grid. As a result, the grid voltage feedforward control with the BPF can ensure that the grid-connected inverter works stably in the weak grid with small short current ratio (SCR) range of the grid impedance. Finally, the experiments on a 66kW inverter prototype have verified the theoretical analyses and the effectiveness of the proposed improved method.
杨树德, 同向前, 尹军, 王海燕, 邓亚平. 增强并网逆变器对电网阻抗鲁棒稳定性的改进前馈控制方法[J]. 电工技术学报, 2017, 32(10): 222-230.
Yang Shude, Tong Xiangqian, Yin Jun, Wang Haiyan, Deng Yaping. An Improved Grid Voltage Feedforward Strategy for Grid-Connected Inverter to Achieve High Robust Stability Against Grid-Impedance Variation. Transactions of China Electrotechnical Society, 2017, 32(10): 222-230.
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