People are diligent, and spring comes early. At present, the land of China has pressed the "fast forward" button for production and labor. In the fields, spring plowing and spring irrigation are busy; In the factory, machines roar and lights are brightly lit. At this moment, in the fourth floor of the State Grid Corporation of China Simulation Center (hereinafter referred to as the "Simulation Center") located in Haidian District, Beijing, electromagnetic transient simulation calculations are running at full speed. Rows of cabinets flicker rhythmically with lights, like breathing, guarding the power grid. This is the recently selected domestically produced large-scale power system electromagnetic transient simulation technology and platform as one of the "Top 10 Central Enterprises in 2023". Relying on it, China's power grid, which has the highest voltage level, the largest scale, the most complex structure, and the fastest development of clean energy in the world, has maintained the longest safe operation record for many years. Is there any defect in bidding farewell to the "inability to imitate" power grid design? Is the system stable or not? Conducting grid simulation analysis in advance is the most effective means of making judgments. "In 2010, with the acceleration of the construction of ultra-high voltage direct current transmission projects, our original simulation methods were not very effective!" Li Yalou, Deputy Director of the Simulation Center, told Science and Technology Daily reporters. The main reason for this is that newly connected equipment is rich in various power electronic devices, and previous electromechanical transient simulation methods could not accurately simulate the rapid response and complex control characteristics of these devices. What technology should be used to replace it? Is the electromagnetic transient simulation technology that has been successfully used in local power grids feasible? Questions linger in the mind of Zhu Yiying, the director of the Digital Analog Hybrid Simulation Research Office at the Simulation Center. At that time, experts in the simulation field generally believed that electromagnetic transient simulation had small step sizes, low computational efficiency, and complex modeling, making it impossible to simulate large-scale actual power grids. Zhu Yiying leans towards not believing in evil. She led a group of researchers in their early thirties, determined to conquer this "mountain". With the passage of time, the R&D team has successively overcome difficulties in large power grid simulation numerical calculation methods, parallel decoupling algorithms, and decentralized synchronous mixed simulation technology. They have developed technologies such as automatic construction of specified power flows and data communication transmission, especially breaking through the crucial 50 microsecond step real-time simulation technology. "A real-time simulation step of 50 microseconds means that the system needs to perform 20000 calculations on 6000 nodes in the East China Power Grid within 1 second," explained Zhu Yiying. "Each CPU core needs to complete its own tasks, interact with data from other CPU cores, and interact with tens of thousands of signals from external physical devices, and the calculation speed must be synchronized with the actual physical process." In Zhu Yiying's view, this is like training the digital power grid to "take small steps". On a summer night in 2017, the simulation center laboratory was brightly lit, with hundreds of CPU cores running rapidly and tens of thousands of signals interacting in real-time. When the simulation results of the fault simulation model almost overlapped with the actual waveform, enthusiastic cheers erupted on site - this means that the East China regional power grid, which includes 11 DC circuits, has achieved accurate real-time simulation of electromagnetic transients for the first time, and the large power grid has been simulated! Cracking the Accurate Simulation of "Imitation Error"