Research on control strategies for rapid load decrease events in fluoride salt reactor-supercritical CO2 Brayton cycle systems

IF 1.9 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Nuclear Engineering and Design Pub Date : 2025-05-08 DOI:10.1016/j.nucengdes.2025.114114

Yun Shichang , Li Xinyu , Zhang Dalin , Song Ping , Tian Wenxi , Qiu Suizheng , Su Guanghui

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引用次数: 0

Abstract

This study delves into the control strategies for the Fluoride-salt-cooled High-temperature Reactor-Supercritical CO₂ (SCO₂) Brayton cycle power generation system under rapid grid load reduction scenarios. By developing a dynamic simulation model, the system’s dynamic response characteristics under rapid load changes were analyzed, and a combined control strategy emphasizing safety, speed, and economic efficiency was proposed.

The research first compared the dynamic response characteristics and steady-state performance of different bypass configurations under load rejection conditions. The computational results indicate that all three bypass control systems exhibit excellent load-following capabilities, effectively responding to a 50 % load step change within 10 s. However, significant differences were observed in their steady-state thermodynamic performance: the upper cycle bypass control achieves the highest steady-state efficiency (η = 29.92 %), followed by the turbine bypass control (η = 27.50 %), with the heat source bypass control showing relatively lower efficiency (η = 26.49 %). Although the upper cycle bypass offers superior efficiency, it leads to a substantial increase in the working fluid flow through the compressor (ΔQ = 15 %) during operation, raising the risk of compressor blockage and necessitating additional flow restriction and anti-blocking interlock control systems. Considering system safety, control complexity, and engineering feasibility, the turbine bypass system, with its relative independence and lower operational risk, is deemed more suitable as the primary control strategy for load rejection conditions.

Building on this, the study proposes a combined control strategy that leverages the strengths of both bypass control and inventory control. During the initial phase of rapid load reduction, the bypass control system quickly adjusts the turbine bypass valve opening to promptly respond to grid load changes, ensuring system frequency stability around 50 Hz, with a maximum deviation of only 0.0193 Hz. Once the load stabilizes, the inventory control system gradually adjusts system pressure and flow rate, reducing bypass flow and ultimately enhancing the system’s thermal efficiency to a new steady-state level. In the four load reduction cases (50 %, 60 %, 70 %, 80 %), the system’s thermal efficiency increases from 27.49 %, 31.25 %, 34.61 %, and 37.63 % to 33.88 %, 36.38 %, 38.43 %, and 40.03 %, respectively. The study also found that even in the 50 % load reduction case, the frequency remains stable around 50 Hz, with a maximum deviation of 0.0193 Hz.

This research provides theoretical and practical guidance for the control strategy of SCO₂ Brayton cycle systems under rapid load changes, significantly enhancing system safety, efficiency, and reliability, and laying a technical foundation for future wide-load operation in nuclear energy applications.

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氟盐堆-超临界CO2布雷顿循环系统快速减载事件控制策略研究

研究了电网快速减负荷情况下氟盐冷高温堆-超临界CO2 （SCO2）布雷顿循环发电系统的控制策略。通过建立动态仿真模型，分析了负载快速变化下系统的动态响应特性，提出了安全、速度和经济效益相结合的控制策略。研究首先比较了不同旁路配置在甩负荷条件下的动态响应特性和稳态性能。计算结果表明，三种旁路控制系统均表现出优异的负载跟踪能力，可有效响应10 s内50%的负载阶跃变化。但两者的稳态热力学性能存在显著差异：上循环旁通控制的稳态效率最高（η = 29.92%），其次是涡轮旁通控制（η = 27.50%），热源旁通控制的稳态效率相对较低（η = 26.49%）。虽然上循环旁路提供了卓越的效率，但在运行过程中，它会导致通过压缩机的工作流体流量大幅增加（ΔQ = 15%），从而增加了压缩机堵塞的风险，因此需要额外的流量限制和防堵联锁控制系统。考虑到系统安全性、控制复杂性和工程可行性，汽轮机旁通系统具有相对独立性和较低的运行风险，更适合作为甩负荷工况的主要控制策略。在此基础上，本研究提出了一种综合利用旁路控制和库存控制优势的综合控制策略。在负荷快速减载初期，旁路控制系统快速调整汽轮机旁通阀开度，及时响应电网负荷变化，保证系统频率稳定在50 Hz左右，最大偏差仅为0.0193 Hz。一旦负荷稳定，库存控制系统逐渐调整系统压力和流量，减少旁通流量，最终将系统热效率提高到一个新的稳态水平。在负荷降低50%、60%、70%、80% 4种情况下，系统热效率分别从27.49%、31.25%、34.61%、37.63%提高到33.88%、36.38%、38.43%、40.03%。研究还发现，即使在负荷减少50%的情况下，频率仍然稳定在50 Hz左右，最大偏差为0.0193 Hz。本研究为SCO2布雷顿循环系统在负荷快速变化下的控制策略提供了理论和实践指导，显著提高了系统的安全性、效率和可靠性，为未来核能应用中的大负荷运行奠定了技术基础。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nuclear Engineering and Design 工程技术-核科学技术

CiteScore

3.40

自引率

11.80%

发文量

377

审稿时长

5 months

期刊介绍： Nuclear Engineering and Design covers the wide range of disciplines involved in the engineering, design, safety and construction of nuclear fission reactors. The Editors welcome papers both on applied and innovative aspects and developments in nuclear science and technology. Fundamentals of Reactor Design include: • Thermal-Hydraulics and Core Physics • Safety Analysis, Risk Assessment (PSA) • Structural and Mechanical Engineering • Materials Science • Fuel Behavior and Design • Structural Plant Design • Engineering of Reactor Components • Experiments Aspects beyond fundamentals of Reactor Design covered: • Accident Mitigation Measures • Reactor Control Systems • Licensing Issues • Safeguard Engineering • Economy of Plants • Reprocessing / Waste Disposal • Applications of Nuclear Energy • Maintenance • Decommissioning Papers on new reactor ideas and developments (Generation IV reactors) such as inherently safe modular HTRs, High Performance LWRs/HWRs and LMFBs/GFR will be considered; Actinide Burners, Accelerator Driven Systems, Energy Amplifiers and other special designs of power and research reactors and their applications are also encouraged.