TY - GEN
T1 - Improvement of grid current quality for droop-controlled grid-connected inverters under distorted grid conditions
AU - Liu, Baojin
AU - Liu, Jinjun
AU - Liu, Zeng
N1 - Publisher Copyright:
© 2019 IEEE.
PY - 2019/9
Y1 - 2019/9
N2 - Grid-connected inverters based on droop control have been widely used in distributed generation (DG) systems, as they can ensure smooth transition between grid-connected mode and islanded mode. However, the traditional active power-frequency (P-ω) and reactive power-amplitude (Q-E) droop control method is vulnerable to the grid voltage distortion, because of the following two reasons. Firstly, the inverter under droop control behaves like a controlled voltage source connected in parallel with utility grid, and the grid current is not directly controlled. Secondly, the line impedance interlinking the inverter and the grid is usually very small, so a slight distortion in grid voltage can lead to serious distortion in grid current. To suppress grid current distortion, this paper proposes to employ harmonic virtual impedance (HVI), which is effective only at harmonic frequency, to increase the equivalent impedance between inverter and grid. Compared with the existing control methods, the proposed HVI control scheme does not need to detect grid voltage and it is easy to be implemented. Comprehensive simulation and experimental results are provided to validate the effectiveness of the proposed method.
AB - Grid-connected inverters based on droop control have been widely used in distributed generation (DG) systems, as they can ensure smooth transition between grid-connected mode and islanded mode. However, the traditional active power-frequency (P-ω) and reactive power-amplitude (Q-E) droop control method is vulnerable to the grid voltage distortion, because of the following two reasons. Firstly, the inverter under droop control behaves like a controlled voltage source connected in parallel with utility grid, and the grid current is not directly controlled. Secondly, the line impedance interlinking the inverter and the grid is usually very small, so a slight distortion in grid voltage can lead to serious distortion in grid current. To suppress grid current distortion, this paper proposes to employ harmonic virtual impedance (HVI), which is effective only at harmonic frequency, to increase the equivalent impedance between inverter and grid. Compared with the existing control methods, the proposed HVI control scheme does not need to detect grid voltage and it is easy to be implemented. Comprehensive simulation and experimental results are provided to validate the effectiveness of the proposed method.
KW - Current quality
KW - Droop control
KW - Grid distortion
KW - Grid-connected
KW - Virtual impedance
UR - https://www.scopus.com/pages/publications/85076782997
U2 - 10.1109/ECCE.2019.8912855
DO - 10.1109/ECCE.2019.8912855
M3 - 会议稿件
AN - SCOPUS:85076782997
T3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019
SP - 2560
EP - 2565
BT - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 11th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2019
Y2 - 29 September 2019 through 3 October 2019
ER -