Stationary Frame Current Control Evaluations for Three-Phase Grid-Connected Inverters with PVR-based Active Damped LCL Filters
Stationary Frame Current Control Evaluations for Three-Phase Grid-Connected Inverters with PVR-based Active Damped LCL Filters
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DOI：
10.6113/jpe.2016.16.1.297
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发表时间：
2016-01
影响因子：
1.4
通讯作者：
Yang Han;Pan Shen;J. Guerrero
中科院分区：
文献类型：
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作者：
Yang Han;Pan Shen;J. Guerrero
带有LCL输出滤波器的并网逆变器(GCI)具有抑制高频(HF)开关纹波的能力。然而，如果只使用电网电流控制，如果没有适当的阻尼，系统很容易发生谐振，并且在严重失真的电网条件下，电流失真被显著放大。针对并网分布式发电系统的LCL谐振问题，提出了一种在αβ静止坐标系下采用基于虚拟电阻的并行有源阻尼控制策略的同步参考系等效比例积分控制器。虽然αβ静止坐标系中的比例谐振(PR)控制器和dq同步坐标系中的PI控制器都实现了零稳态误差，但除了基频上的参考跟踪外，它们的幅频和相频特性差别很大。因此，在αβ静止坐标系中建立了一个精确的SRF-EPI控制器，以达到精确的跟踪精度。利用奈奎斯特稳定性判据，研究了采用基于PVR的AD方法时，系统的鲁棒性、谐波抑制能力以及控制延迟对系统稳定性的影响。此外，在电流环中集成了电网电压前馈和多个PR控制器，以缓解电网背景失真带来的电流失真。此外，还给出了参数设计准则，以说明所提策略的有效性。最后，给出了仿真和实验结果，验证了该控制方法的可行性。
Grid-connected inverters (GCIs) with an LCL output filter have the ability of attenuating high-frequency (HF) switching ripples. However, by using only grid-current control, the system is prone to resonances if it is not properly damped, and the current distortion is amplified significantly under highly distorted grid conditions. This paper proposes a synchronous reference frame equivalent proportional-integral (SRF-EPI) controller in the αβ stationary frame using the parallel virtual resistance-based active damping (PVR-AD) strategy for grid-interfaced distributed generation (DG) systems to suppress LCL resonance. Although both a proportional-resonant (PR) controller in the αβ stationary frame and a PI controller in the dq synchronous frame achieve zero steady-state error, the amplitude- and phase-frequency characteristics differ greatly from each other except for the reference tracking at the fundamental frequency. Therefore, an accurate SRF-EPI controller in the αβ stationary frame is established to achieve precise tracking accuracy. Moreover, the robustness, the harmonic rejection capability, and the influence of the control delay are investigated by the Nyquist stability criterion when the PVR-based AD method is adopted. Furthermore, grid voltage feed-forward and multiple PR controllers are integrated into the current loop to mitigate the current distortion introduced by the grid background distortion. In addition, the parameters design guidelines are presented to show the effectiveness of the proposed strategy. Finally, simulation and experimental results are provided to validate the feasibility of the proposed control approach.