| Title |
Grid Voltage Estimation Scheme without Phase Delay in Voltage-sensorless Control of a Grid-connected Inverter |
| Authors |
Hyun-Sou Kim ; Kyeong-Hwa Kim |
| DOI |
https://doi.org/10.6113/TKPE/2018.22.1.89 |
| Keywords |
DOB(Disturbance observer) based controller ; Grid-connected inverter ; Grid voltage estimation ; Phase lead compensator ; Voltage-sensorless control |
| Abstract |
This study proposes a grid voltage estimation scheme without a phase delay in the voltage-sensorless control of a grid-connected inverter to enhance its economic feasibility, such as manufacturing cost and system complexity. The proposed scheme estimates grid voltages using a disturbance observer (DOB)-based current controller to control the grid-connected inverter without grid-side voltage sensors. The proposed voltage-sensorless control scheme can be applied successfully to grid-connected inverters, which should be operated with synchronization to the grid, considering the phase angle of the grid can be effectively detected through estimating the grid voltages by DOB. However, a problem associated with the phase delay in estimated grid voltages remains because the DOB has dynamic behavior similar to low-pass filter. Hence, the estimated grid voltages are compensated by a phase lead compensator to overcome the limitation. The effectiveness of the proposed control and estimation schemes is proven through simulations and experiments using a 2 kVA prototype inverter. |