Analysis and Research on Control Strategy of Supercritical Carbon Dioxide Recompression System

Abstract This article takes the supercritical carbon dioxide recompression cycle system as the research object, and analyzes different control methods such as speed control (including compressor speed regulation and turbine speed regulation), volume control (including changing compressor inlet pressure and compressor inlet temperature), and throttling control under established thermodynamic parameters. Based on the characteristics of the cycle and the characteristics of a single control method, a control strategy combining multiple control methods with different load intervals and mobility requirements is proposed. The research results indicate that speed control has the highest efficiency under partial load conditions among various methods, followed by volume control and throttling control. There are depth limits for load reduction in a single control method, and compressor surge and outlet pressure over pressure may occur in different load ranges. Based on the characteristics of different load intervals and regulation methods, we propose a combination control strategy scheme. When 0% FP ≤ load level < 20% FP, a combined control scheme of throttling control and bypass control is adopted; When 20% FP ≤ load level < 90% FP, the most efficient speed control scheme is adopted, which adopts speed gear adjustment to avoid frequent equipment actions. When 90% FP ≤ load level ≤ 100% FP, volume control is adopted.