The reliability assessment method of electric hydrogen regional integrated energy system is a key component of the planning theory of electric hydrogen regional integrated energy system, which has important theoretical research value and engineering application prospects. The existing reliability assessment methods do not fully consider the failure mechanism of hydrogen energy equipment and its multi-state operation characteristics, and lack quantitative evaluation indicators of hydrogen supply reliability level. Researchers from the Electric Power and Energy Reliability Research Center of Chongqing University analyzed the operating characteristics and failure mechanisms of hydrogen energy equipment, established a multi-state reliability evaluation model of hydrogen energy equipment, and proposed a reliability evaluation method for electric hydrogen regional comprehensive energy system based on the multi-state model of hydrogen energy equipment, so as to accurately quantify the reliability level of electric hydrogen heterogeneous energy supply.
Background:
Under the strategic goal of "dual carbon", the clean and low-carbon transformation of the mainland's energy system is imminent. The electric hydrogen regional integrated energy system can give full play to the advantages of zero-carbon, flexible and efficient operation of the hydrogen energy system, and is considered to be one of the key paths to realize the green and low-carbon transformation of the power energy system. The reliability assessment method of electric hydrogen regional integrated energy system can provide scientific theoretical support and decision-making basis for system planning and operation, and guide the orderly and healthy development of hydrogen energy.
The problem solved by the paper and its significance
The hydrogen energy system includes hydrogen production, hydrogen storage, hydrogen use, hydrogen refueling and other links, involving key equipment such as electrolyzers, hydrogen storage tanks, fuel cells, hydrogen refueling machines, etc., and the failure mechanism of hydrogen energy equipment is complex, and the existing reliability model does not dig deep into its multi-state operation characteristics, which makes it difficult to accurately evaluate the energy supply reliability level of the system.
In addition, there is a strong coupling relationship between heterogeneous energy systems such as electricity, hydrogen, and heat, and there is still a lack of effective reliability evaluation methods and hydrogen supply reliability evaluation indicators for electric hydrogen regional integrated energy systems, which cannot quantify the reliability level of hydrogen load supply, and it is difficult to determine the key factors affecting the reliability of hydrogen supply. Therefore, how to construct a reliability model of hydrogen energy equipment and accurately quantify the supply reliability of heterogeneous energy sources such as hydrogen energy has become a key problem to be solved in the reliability evaluation method of electric hydrogen integrated energy system.
Dissertation Methods and Innovations
The failure state of hydrogen equipment will directly affect the operating state of the system. Therefore, firstly, at the level of hydrogen energy equipment, according to the operating characteristics and failure mechanism of hydrogen energy equipment, a multi-state reliability evaluation model of hydrogen energy equipment is established.
The modeling of hydrogen energy equipment includes: 1) revealing the influence mechanism of heat exchanger pipe failure on hydrogen production efficiency, and establishing a multi-state model of alkaline electrolyzer considering the derating operating state, 2) analyzing the relationship between fuel cell component failure and thermoelectric conversion efficiency, and establishing a fuel cell multi-state model considering the cogeneration mode, and 3) establishing a multi-state model of hydrogen refueling unit based on the failure of the hydrogen refueling unit and the number of hydrogen refueling units.
Fig.1. Schematic diagram of the structure of the alkaline electrolyzer and its multi-state Markov model
Fig.2. Schematic diagram of the structure of a proton exchange membrane fuel cell and its multi-state Markov model
Fig.3 Multi-state Markov model+ before and after the simplification of the hydrogenation unit
At the level of evaluating the reliability of the system, based on the reliability evaluation model of hydrogen energy equipment, with the goal of minimizing the sum of the penalty cost of curtailment of wind and solar power and the penalty cost of heterogeneous energy load reduction such as hydrogen energy, and comprehensively considering the constraints of heterogeneous energy flow and the operation constraint of hydrogen energy equipment, the optimal load reduction model of the system was established to simulate the system operation state and the shortage of hydrogen energy under the equipment failure state, and based on the Markov chain Monte Carlo method, a reliability assessment method for electric hydrogen regional comprehensive energy system was established.
Fig.4 Schematic diagram of the structure of the regional integrated energy system of electric hydrogen
The simulation results show that the proposed multi-state model of alkaline electrolyzer and hydrogen refueling unit can fully consider the hydrogen load reduction caused by the derating operation state and avoid overestimating the reliability level of hydrogen supply, and the proposed multi-state model of fuel cell can fully consider the contribution of the fuel cell cogeneration model to the reliability of heating supply, and avoid underestimating the reliability level of heat supply.
Table 1 Reliability evaluation indexes of electric hydrogen regional integrated energy system under different methods
In addition, the hydrogen supply contribution index of various types of equipment in the typical example is calculated, and it can be seen that the sum of the hydrogen supply contribution of power lines and wind turbines to the system reaches 32.61%, which is because the random failure of power equipment will lead to the lack of electric energy for hydrogen production in the electrolyzer, resulting in insufficient supply of hydrogen load.
The contribution of the electrolyzer to the hydrogen supply of the system is as high as 53.72%, because the electrolyzer is the only hydrogen production equipment in the system, and its derating operation state and fault outage state will cause a large shortage of hydrogen energy supply. This shows that power equipment and electrolyzers are the key factors affecting the reliability of hydrogen supply.
Fig.5 Contribution index of hydrogen supply of equipment
conclusion
In this paper, the multi-state model of alkaline electrolyzer, cogeneration fuel cell and hydrogen refueling unit is established, the reliability evaluation index of hydrogen supply and the reliability evaluation method of electric hydrogen regional integrated energy system are proposed, and the effectiveness and adaptability of the model and method are verified by case simulation.
About the Author:
Ren Zhouyang
Associate Professor, Doctoral Supervisor, research direction is electric hydrogen integrated energy system, power system probability analysis and artificial intelligence. He has undertaken more than 30 national, provincial and horizontal projects, published more than 80 SCI/EI papers, and applied for/authorized more than 50 national invention patents. He has successively served as an associate editor of 6 internationally renowned journals such as IEEE Trans. on Smart Grid and IEEE Trans. on Sustainable Energy, won 3 provincial and ministerial awards, was selected into the Chongqing Talent-Young Top-notch Talent Program, and won the IEEE Trans. on Sustainable Energy Outstanding Associate Editor of 2022 and other honors.
Wang Hao
Master's degree candidate, research direction is distribution network operation and planning, electric hydrogen regional integrated energy system reliability assessment.
Jiang Yunpeng
Ph.D. candidate, research direction is distribution network new energy consumption, regional integrated energy system, etc.
Li Wenyuan
He is a Foreign Academician of the Chinese Academy of Engineering, an Academician of the Canadian Academy of Engineering, and an IEEE Life Fellow. His research interests include power system reliability and planning, and power system big data. He has published more than 300 papers, completed more than 100 technical reports, and published 6 monographs in Chinese and English. He has won the IEEE PES Roy Billinton Power Reliability Award, the International PMAPS Achievement Award, the Canadian IEEE Outstanding Engineer Award, and the Canadian IEEE Electrical Medal Award.
The results of this work were published in the 24th issue of Transactions of China Electrotechnical Society in 2023, and the title of the paper is "Reliability Assessment of Electric-Hydrogen Regional Integrated Energy System Based on Multi-state Model of Hydrogen Energy Equipment". This project is supported by the National Natural Science Foundation of China.