Abstract
To improve the robustness and stability of the LCL inverter connected to weak grid, this paper proposes a novel active damping based on voltage of point common coupling ( v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pcc</sub> ) feedback. A phase lead compensator is proposed in the v <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pcc</sub> feedback loop to compensate system phase margin (PM). Theoretical analysis of the effectiveness, detailed parameter setting, stability analysis for proposed active damping adopting lead compensator, named as LC AD, are all described. Simulation and experiment results show that comparing to conventional high pass filter (HPF) AD, the proposed LC AD provides more effective damping effect for the LCL inverter adopting quasi-proportional resonant (QPR) controller under weak grid.
Highlights
The grid-connected inverter, together with a filter, plays an important role as the connection hub between distributed renewable power generations and the grid [1]-[3]
With the penetration increasing of distributed generation (DG), the grid impedance cannot be ignored anymore and the grid presents the characteristics of weak grid instead of conventional ideal grid [6]-[7]
To improve the robustness and stability of the LCL inverter connected to weak grid, this paper proposes a novel active damping (AD)
Summary
The grid-connected inverter, together with a filter, plays an important role as the connection hub between distributed renewable power generations and the grid [1]-[3]. This method forms a virtual resistor in parallel with the grid-side inductance [26] and a s2 term appears in the system transfer function, which is usually approximated by a first-order or a high order HPF with a negated output. To improve the robustness and stability of the LCL inverter connected to weak grid, this paper proposes a novel AD In this scheme, a QPR controller is adopted for the LCL inverter and the grid voltage of common coupling point (vpcc) is feeded back to construct a virtual resistor in parallel with the filter capacitor without extra sensor.
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