Development of Molten Salt Electric Heating Control System Based on Monitor and Control Generated System and Programmable Logic Controller

doi:10.12096/j.2096-4528.pgt.21004

Abstract

Abstract:

Molten salt has important applications in renewable energy power generation and energy storage heating system as the heat transfer and storage working fluid. As the constant power heating can easily lead to the burning of electric heater and the decomposition of molten salt, a constant temperature electric heating system is needed for melting and anti-freezing of molten salt system. We used monitor and control generated system (MCGS) configuration software and SIEMENS S7-200PLC, combined with solid-state relay (SSR), thermal resistance and electric heater, to design a closed-loop electric heater temperature PI control system. According to different PI tuning methods for experimental comparison, the contradiction problems of the PI controller over-tuning and anti-interference were solved by adding anti-integral saturation and two-degrees-of-freedom control. While the over-tuning was greatly reduced, the anti-interference function of the temperature of molten salt heat storage system under the interference condition was realized, and the temperature control of molten salt heat storage electric heater was carried out.

Key words: solar energy utilization, heat storage of molten salt, monitor and control generated system (MCGS), programmable logic controller (PLC), temperature control, PI control

CLC Number:

TK519

Chunxu DU, Yancheng MA, Yanquan WANG, Jihao XIE, Jinkai LIU, Yuanwei LU. Development of Molten Salt Electric Heating Control System Based on Monitor and Control Generated System and Programmable Logic Controller[J]. Power Generation Technology, 2021, 42(6): 727-733.

Figures/Tables 11

Fig.1 Schematic diagram of control system for molten salt electric heater

Fig.2 Interface diagram of molten salt electric heater control system with MCGS configuration

Fig.3 Temperature rise curve of electric heater with 10 ms pulse width

Tab. 1 PI parameters of different tuning methods

整定方法	K_p	T_i/s
回路成形法	3.136	345.00
Z-N法	5.390	59.40
C-C法	5.420	54.03
回路成形+SIMC法	3.316	72.00

Fig.4 Temperature rise curve of electric heater with different tuning methods

Tab. 2 Performance comparison of different tuning methods

整定方法	调节时间t/s	超调量σ/%
回路成形法	184	23.6
Z-N法	678	75.1
C-C法	628	70.9
回路成形+SIMC法	367	25.7

Fig.5 Comparison of temperature rise curves of Z-N method before and after anti-integral saturation

Tab. 3 Performance comparison before and after anti-integral saturation

整定方法	调节时间t/s	超调量σ/%
Z-N法	678	75.1
Z-N法+抗积分饱和	392	75.3

Fig.6 Block diagram of pre-filtering 2DOF structure

Fig.7 Comparison of temperature rise curves of Z-N method with anti-integral saturation before and after adding 2DOF filtering

Tab. 4 Performance comparison before and after adding 2DOF filtering

整定方法	调节时间t/s	超调量σ/%
Z-N法+抗积分饱和	392	75.3
Z-N法+抗积分饱和+两自由度	269	12.2

References 20

1	张凯. 电热熔盐换热系统设计与性能研究[D]. 南京: 南京理工大学, 2016.
	ZHANG K. The design and performance research of molten salt electrical heating and heat exchange system[D]. Nanjing: Nanjing University of Science&Technology, 2016.
2	安荣朝. 光热发电厂中熔盐储罐电加热器的设计选型[J]. 中国资源综合利用, 2019, 37 (11): 59- 62. DOI
	AN R C . Design and selection of electric heater for molten salt storage tanks in solar thermal power plants[J]. China Resources Comprehensive Utilization, 2019, 37 (11): 59- 62. DOI
3	李九如, 董喜欣, 陈巨辉, 等. 太阳能&谷电加热熔盐蓄热系统特性[J]. 哈尔滨理工大学学报, 2017, 22 (1): 80- 85.
	LI J R , DONG X X , CHEN J H , et al. The characteristic of molten heat salt storage system utilizing solar energy combined with valley electric[J]. Journal of Harbin University of Science and Technology, 2017, 22 (1): 80- 85.
4	关书伟. 谷电、太阳能设备加热与熔盐蓄热的集中供暖技术应用[J]. 住宅与房地产, 2017, (5): 250.
	GUAN S W . Application of central heating technology of valley power, solar energy equipment heating and molten salt heat storage[J]. Housing and Real Estate, 2017, (5): 250.
5	郑永恒, 李成家, 李杰. 风力-太阳能光热互补发电技术研究[J]. 电力设备管理, 2020, (9): 144- 145.
	Zheng Y H , Li C J , LI J . Research on wind-solar thermal complementary power generation technology[J]. Electric Power Equipment Management, 2020, (9): 144- 145.
6	吴玉庭, 张晓明, 王慧富, 等. 基于弃风弃光或低谷电加热的熔盐蓄热供热技术及其评价[J]. 中外能源, 2017, 22 (2): 93- 99.
	WU Y T , ZHANG X M , WANG H F , et al. Molten salt heat storage and supply technology based on heating using abandoned wind power, PV power or off-peak power[J]. Sino-Global Energy, 2017, 22 (2): 93- 99.
7	刘畅. 高温熔盐蓄热风电系统设计及研究[D]. 上海: 中国科学院大学(中国科学院上海应用物理研究所), 2018.
	LIU C. Design and research of the wind power system with high temperature molten salt thermal energy storage[D]. Shanghai: University of Chinese Academy of Sciences (Shanghai Institute of Applied Physics, Chinese Academy of Sciences), 2018.
8	张哲旸, 巨星, 潘信宇, 等. 太阳能光伏-光热复合发电技术及其商业化应用[J]. 发电技术, 2020, 41 (3): 220- 230.
	ZHANG Z Y , JU X , PAN X Y , et al. Photovoltaic/concentrated solar power hybrid technology and its commercial application[J]. Power Generation Technology, 2020, 41 (3): 220- 230.
9	魏海姣, 鹿院卫, 张灿灿, 等. 燃煤机组灵活性调节技术研究现状及展望[J]. 华电技术, 2020, 42 (4): 57- 63. DOI
	WEI H J , LU Y W , ZHANG C C , et al. Status and prospect of flexibility regulation technology for coal-fired power plants[J]. Huadian Technology, 2020, 42 (4): 57- 63. DOI
10	任晓佳. 电加热技术在固碱生产中的应用[J]. 氯碱工业, 2016, 52 (11): 25- 27. DOI
	REN X J . Application of electric heating technology in solid caustic soda production[J]. Chlor-Alkali Industry, 2016, 52 (11): 25- 27. DOI
11	张鹏, 张俊峰. 风力-太阳能光热互补发电技术[J]. 电站系统工程, 2017, 33 (3): 5- 8.
	ZHANG P , ZHANG J F . Wind-solar thermal power generation complementary technology[J]. Power System Engineering, 2017, 33 (3): 5- 8.
12	李鹏蕾, 陈林根, 夏少军, 等. 基于熔融盐加热的甲烷蒸汽重整制氢反应器的熵产生率和氢气产率分析[J]. 发电技术, 2020, 41 (4): 415- 428.
	LI P L , CHEN L G , XIA S J , et al. Entropy generation rate and hydrogen production rate analyses for steam methane reforming reactor heated by molten salt[J]. Power Generation Technology, 2020, 41 (4): 415- 428.
13	黄平瑞, 周震, 魏高升, 等. 基于多孔陶瓷的体吸收太阳能集热器性能分析[J]. 发电技术, 2019, 40 (1): 83- 90.
	HUANG P R , ZHOU Z , WEI G S , et al. Performance analysis of volumetric solar receiver based on porous foam ceramics[J]. Power Generation Technology, 2019, 40 (1): 83- 90.
14	邢毓华, 刘兴, 程绍谦. 基于太阳能充电站中风光火多目标优化管理问题的研究[J]. 计算机测量与控制, 2019, 27 (7): 174- 179.
	XING Y H , LIU X , CHENG S Q . Research on multi-objective optimization management problem of wind power, photovoltaic and thermal based on solar charging station[J]. Computer Measurement&Control, 2019, 27 (7): 174- 179.
15	刘兰华, 王瑞林, 洪慧. 塔式太阳能辅助燃气蒸汽联合循环钙基碳捕集系统设计[J]. 发电技术, 2021, 42 (4): 517- 524.
	LIU L H , WANG R L , HONG H . Design of calcium-based carbon capture system for gas-steam combined cycle assisted by solar thermal tower[J]. Power Generation Technology, 2021, 42 (4): 517- 524.
16	ASTROM K J , HAGGLUND T . PID controllers theory, design and tuning[M]. North Carolina: Instrument Society of America, 1995.
17	ZIEGLER J G , NICHOLS N B . Optimum setting for automatic controllers[J]. Journal of Dynamic Systems Measurement&Control, 1993, 115 (2B): 220- 222.
18	SKOGESTAD S . Simple analytic rules for model reduction and PID controller tuning[J]. Journal of Process Control, 2004, 13 (4): 291- 309.
19	HÄGGLUND T , ÅSTRÖM K J . Revisiting the Ziegler-Nichols tuning rules for PI control: part Ⅱ: the frequency response method[J]. Asian Journal of Control, 2004, 6 (4): 469- 482.
20	ARAKI M . Two degree of freedom PID controller[J]. International Journal of Control Automation and Systems, 2003, 1 (4): 401- 411.

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