Control Strategy for a Grid-Connected Inverter under Unbalanced Network Conditions—A Disturbance Observer-Based Decoupled Current Approach

An improved control strategy for three-phase grid-connected inverters with space vector pulse width modulation (SVPWM) is proposed. When the grid current contains harmonics, the d-and q-axes grid currents is interacted in the traditional control method, and the waveform quality of the grid current is poor. As the reference output voltage cannot directly reflect the change of the reference grid current with the traditional control strategy, the dynamic response of the grid-connected inverter is slow. In order to solve the aforementioned problems, the d-and q-axes grid currents in the decoupled components of the grid current controller are substituted by the d-and q-axes reference grid currents, respectively. The operating principles of the traditional and proposed control methods are illustrated. Experimental results show that the grid-connected inverter with the improved control strategy has high waveform quality of the grid current and fast dynamic response.

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A Capacitor-Current-Feedback Positive Active Damping Control Strategy for LCL-Type Grid-Connected Inverter to Achieve High Robustness

IEEE Transactions on Power Electronics ◽

10.1109/tpel.2021.3137845 ◽

2021 ◽

pp. 1-1

Author(s):

Shaojie Li ◽

Hua Lin

Keyword(s):

Control Strategy ◽

Active Damping ◽

Current Feedback ◽

Damping Control ◽

Grid Connected Inverter ◽

Active Damping Control

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Active and Reactive Power Compensation Control Strategy for VSC-HVDC Systems under Unbalanced Grid Conditions

Energies ◽

10.3390/en11113140 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3140 ◽

Cited By ~ 3

Author(s):

Weiming Liu ◽

Tingting Zheng ◽

Ziwen Liu ◽

Zhihua Fan ◽

Yilong Kang ◽

...

Keyword(s):

Control Strategy ◽

Disturbance Observer ◽

Reactive Power ◽

Operating Conditions ◽

Voltage Source ◽

Double Frequency ◽

Compensation Control ◽

Active And Reactive Power ◽

Passivity Based Control ◽

Unbalanced Grid

This paper presents a power compensation strategy to suppress the double frequency power ripples of Voltage source converter high-voltage direct current (VSC-HVDC) systems under unbalanced grid voltage conditions. The mathematical control equations of the double frequency ripple power of VSC under unbalanced operating conditions are firstly derived and established, where the dynamic behaviors of the double frequency ripples in active and reactive power are regarded as being driven by current-relevant components and voltage-relevant components, respectively. Based on the equations, a power compensation control strategy of VSC-HVDC is proposed via the passivity-based control with disturbance observer to suppress both the current-relevant and voltage-relevant components in the power ripples. With this control strategy, the double frequency ripples in active and reactive power are suppressed simultaneously and system performance is significantly enhanced with the implementation of the disturbance observer in the passivity-based control. Theoretical stability analysis and simulation cases show the effectiveness and superiority of the proposed strategy.

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