The inverter becomes an essential part in the distributed energy units, where an inductor–capacitor–inductor (LCL) filter is an up-to-date adoption for grid interfacing. However, the challenging issue of resonance related to the LCL-filter worsens the dynamic control characteristics and produces stability threat for the voltage source inverter system. The proper design of inverter control plays a substantial part in ensuring a steady state operation and a high quality of grid injected current according to grid connection codes. This paper offers a different design method of inverter control which alters the inner damping loop structure to enhance the damping and stability features of the inverter system. In the proposed solution, a modified compensator is employed through the LCL filter network and filter capacitor current feedback loop, the resultant augmented plant’s output is then sent back at the reference point of a grid-connected inverter system to damp the unwanted resonance spike. This particular arrangement to form a damping loop is termed as parallel feedforward compensation. The damping loop is implemented by calculating the filter capacitor current, and a first order high-pass filter is employed as a damper in the suggested arrangement. Moreover, for comparative studies and analysis, the conventional filter capacitor current feedback active damping method is selected. In addition, the stability margins and control performance of the open current loop are examined under different filter parameters values. The substantial results of the suggested structure are quicker dynamic response, comparatively improved resonance damping, better tracking performance and higher delay compensation capability. A laboratory prototype is established to confirm the effectiveness of the suggested scheme on the bases of control performance and stability margins.

中文翻译：

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LCL型并网逆变器谐振阻尼控制与分析

逆变器成为分布式能源装置中的重要组成部分，其中电感器-电容器-电感器（LCL）滤波器是电网接口的最新采用。然而，与 LCL 滤波器相关的具有挑战性的谐振问题恶化了动态控制特性，并对电压源逆变器系统产生稳定性威胁。根据并网规范，逆变器控制的正确设计对于确保稳态运行和高质量的电网注入电流起着重要作用。本文提出了一种不同的逆变器控制设计方法，它改变了内阻尼环结构，以增强逆变器系统的阻尼和稳定性特性。在所提出的解决方案中，通过 LCL 滤波器网络和滤波电容器电流反馈环路采用改进的补偿器，然后将所得增强设备的输出发送回并网逆变器系统的参考点，以抑制不需要的谐振尖峰。这种形成阻尼环路的特殊布置被称为并行前馈补偿。阻尼环路是通过计算滤波电容器电流来实现的，并且在建议的布置中采用一阶高通滤波器作为阻尼器。此外，为了进行对比研究和分析，选择了传统的滤波电容电流反馈有源阻尼方法。此外，还考察了不同滤波器参数值下开路电流环路的稳定性裕度和控制性能。该结构的实质成果是更快的动态响应、相对改善的共振阻尼、更好的跟踪性能和更高的延迟补偿能力。建立了一个实验室原型，以在控制性能和稳定性裕度的基础上确认建议方案的有效性。