High penetration of distributed generations and active loads have enabled the power electronics converter to become a vital component in the modern power grid system, and the broad employment of grid-connected converters at various power levels is making the grid impedance and characteristics complicated. Consequently, in order to validate more advanced features such as the reliability and stability performances of the grid-connected converters, it is becoming an emerging need to emulate the grid behaviors from more aspects. This article serves to foster and investigate the state-of-the-art techniques in the field of ac grid emulation from the perspective of multiple spatial-scales and multiple time-scales. Four major concepts used for grid emulation with featured principles, including concept I (analog simulation with under-scaled components), concept II (grid characteristics in the real-time simulator), concept III (grid characteristics in the converters structure), and concept IV (grid characteristics in the converters controller), are summarized, respectively, in this article. The practical implementation regarding to the circuit topology and the power supply for the grid emulation system are also discussed. Finally, the future trends and conclusions in the field of ac grid emulation are provided.

中文翻译：

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用于并网转换器高级测试的交流电网仿真

分布式电源和有源负载的高渗透率使电力电子变流器成为现代电网系统中的重要组成部分，而并网变流器在各种功率级别的广泛应用使得电网阻抗和特性变得复杂。因此，为了验证并网变流器的可靠性和稳定性等更先进的特性，从更多方面模拟电网行为正成为新兴需求。本文旨在从多空间尺度和多时间尺度的角度培养和研究交流电网仿真领域的最新技术。用于具有特色原理的网格仿真的四个主要概念，包括概念 I（具有欠缩放组件的模拟仿真），本文分别总结了概念 II（实时模拟器中的电网特性）、概念 III（转换器结构中的电网特性）和概念 IV（转换器控制器中的电网特性）。还讨论了有关电网仿真系统的电路拓扑和电源的实际实现。最后，给出了交流电网仿真领域的未来发展趋势和结论。