School of Mechanical and Electrical Engineering, Institute for Electric Vehicle Driving System and Safety Technology, University of Electronic Science and Technology of China, Chengdu, China.
School of Automation, Institute for Electric Vehicle Driving System and Safety Technology, University of Electronic Science and Technology of China, Chengdu, China.
ISA Trans. 2019 Sep;92:257-272. doi: 10.1016/j.isatra.2019.02.019. Epub 2019 Mar 1.
Integration of renewable energy (RE) sources, such as wind energy and photo voltaic (PV) energy, to a power network (grid) is usually achieved through an intermediate power electronic inverter. Ideally, the inverter is not expected to inject any form of DC component into the grid. However, this is not the case in practice as DC component are invariably generated and, subsequently, injected into the grid by the power converter, impacting on the overall power quality. To mitigate this problem, the International Grid Certification stipulates the maximum extent of DC component that can be injected into the grid current. Thus, various techniques have been proposed to maintain the DC component within the stipulated limit, however these techniques have the drawbacks of complicated control algorithm, extra power losses, and increased high costs. To solve these problems, this paper proposes a virtual-capacitor based DC current suppression control technique for grid-connected inverters, which has the advantages of fast implementation and good DC component suppression performance in utility. An LCL filter interfaced 3-phase inverter is used and virtual capacitors are incorporated into the inverter which connects the inverter with the grid. The allowable region and design methods of the inverter controller parameters which are combined with the active damping and grid voltage feedforward strategies are described in detail. Furthermore, both simulation and experimental results show that the DC component can be successfully mitigated and could satisfy the International Grid Certification standards.
可再生能源（RE），如风能和光伏（PV）能源，与电网的集成通常是通过中间电力电子逆变器实现的。理想情况下，逆变器不应向电网注入任何形式的直流分量。然而，在实际中并非如此，因为直流分量总是由功率转换器产生并随后注入电网，从而影响整体电能质量。为了解决这个问题，国际电网认证规定了可注入电网电流的最大直流分量。因此，已经提出了各种技术来将直流分量保持在规定的限制内，但是这些技术具有控制算法复杂、额外功率损耗和增加成本高的缺点。为了解决这些问题，本文提出了一种基于虚拟电容的并网逆变器直流电流抑制控制技术，该技术在实用中具有快速实现和良好的直流分量抑制性能的优点。使用了连接逆变器和电网的 LCL 滤波器接口三相逆变器，并在逆变器中并入虚拟电容器。详细描述了与有源阻尼和电网电压前馈策略相结合的逆变器控制器参数的允许区域和设计方法。此外，仿真和实验结果均表明，直流分量得到了有效抑制，满足国际电网认证标准。
