In the inverter grid-connected system with weak grid, the existence of grid impedance and voltage harmonic perturbation will cause the distortion of grid-connected current, and the traditional voltage full feedforward method reduces the steady-state error but affects the quality of current, and even threatens the instability of the system. To address the above problems, it is proposed to improve the grid voltage feedforward, i.e., to add resonant feedforward in the feedforward channel to offset the influence of grid impedance, and at the same time ensure the system open-loop gain, increase the system margin, and improve the stability; and secondly to introduce a proportional multi-resonance controller instead of the traditional proportional integral controller, which is used to suppress the influence of grid harmonics on the grid-connected currents, and then to lower the harmonic content of the grid-connected currents and improve the quality of grid-connected currents. Finally, the effectiveness of the control strategy is verified by simulation.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |