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Recently, the Electrical and Instrumentation Center of Zhongyuan Petrochemical completed the transformation of the PLCs in air separation compressors by using domestic control systems, achieving 100% domestic ownership of the control systems for these compressors. This move broke the foreign companies’ monopoly on control systems for such compressors in China, and reduced the costs associated with system transformation by 50%. The original air separation compressor used a single-board computer encryption system from a certain manufacturer; when the unit experienced shutdowns or alarms, it was not possible to determine the exact cause of these issues. Moreover, the system had been in operation for 16 years, exceeding the typical service life of PLC systems. Sudden failures in the control system occurred during operation, which had a significant impact on production stability. Due to the high costs associated with upgrading the original system and the confidentiality of its software, the company decided to undertake technical efforts to localize and modify this \"black box\". As the technology for the localization transformation of compressor control systems was used for the first time in our company, significant difficulties were encountered during the initial operation of the equipment, including issues related to the logic for the sequential start-up and shutdown of the compressors, as well as the difficulty in identifying the surge point. Faced with these technical challenges, the Electrical Instruments Center organized key Party members to form a task force. Relying on Technician Rao Jun’s workshop, they developed a compressor simulation system for testing purposes. Without any reference materials or operation instructions, they started by studying the principles of compressor operation and its relevant parameters. After more than 10 days of continuous technical efforts and over 100 repeated simulation tests, they managed to determine the correct logic for starting and stopping the compressor as well as its surge curve. Ultimately, the unit succeeded in its first trial run, operating smoothly with excellent performance. After the successful trial operation of the unit, the technical team immediately turned its attention to another challenge: how to solve the problem of remote data transmission. Communication between the unit and the DCS has always been a difficult issue; although the communication patterns of different unit control systems are generally similar, there are still differences among them, and an incorrect parameter setting can prevent data from being transmitted remotely. After two days of non-stop efforts, the successful transmission of data from the control system to the DCS marked the complete completion of the technical renovation of the air separation compressors. The successful domestic application of the compressor PLC control system has also provided valuable experience for the subsequent domestic transformation of components such as the instrument air molecular sieve controller and the MTO wastewater pretreatment flare.