Electromagnetic transient (EMT) simulation is a crucial tool for power system dynamic analysis because of its detailed component modeling and high simulation accuracy. However, it suffers from computational burdens for large power grids since a tiny time step is typically required for accuracy. This paper proposes an efficient and accurate semi-analytical approach for state-space EMT simulations of power grids. It employs high-order semi-analytical solutions derived using the differential transformation from the state-space EMT grid model. The approach incorporates a proposed variable time step strategy based on equation imbalance, leveraging structural information of the grid model, to enlarge the time step and accelerate simulations, while high resolution is maintained by reconstructing detailed fast EMT dynamics through an efficient dense output mechanism. It also addresses limit-induced switches during large time steps by using a binary search-enhanced quadratic interpolation algorithm. Case studies are conducted on EMT models of the IEEE 39-bus system and a synthetic 390-bus system to demonstrate the merits of the new simulation approach against traditional methods.

翻译：电磁暂态仿真因具备详细的元件建模和高仿真精度，成为电力系统动态分析的关键工具。然而，由于通常需采用极小时间步长以保证精度，该方法在处理大型电网时面临计算负担沉重的问题。本文提出一种高效且精确的半解析方法，用于电网的状态空间电磁暂态仿真。该方法利用状态空间电磁暂态电网模型通过微分变换推导的高阶半解析解。文中提出一种基于方程不平衡度的变步长策略，借助电网模型的结构信息来增大时间步长并加速仿真，同时通过高效的密集输出机制重构详细的快速电磁暂态动态，从而保持高分辨率。此外，针对大步长下可能发生的限幅触发开关动作，采用二进制搜索增强的二次插值算法进行处理。通过对IEEE 39节点系统及合成390节点系统的电磁暂态模型进行实例研究，验证了该新仿真方法相较于传统方法的优势。