Water-wind-light-hydrogen multi-energy complementary off-grid system comprehensive benefit evaluation method based on TOPSIS

Abstract

The invention belongs to the technical field of comprehensive energy systems, and particularly relates to a water-wind-light-hydrogen multi-energy complementary off-grid system comprehensive benefit evaluation method based on TOPSIS. According to the technical scheme, the TOPSIS-based comprehensive benefit evaluation method for the water-wind-light-hydrogen multi-energy complementary off-grid system comprises the following steps: S1, determining an evaluation object; s2, determining a construction principle of an evaluation index system; s3, determining a construction method of comprehensive benefit evaluation indexes of the water-wind-light-hydrogen storage multi-energy complementary off-grid system; s4, determining a multi-energy complementary off-network system comprehensive benefit multi-level index weighting method; and S5, comprehensive benefit evaluation result calculation and analysis are carried out based on TOPSIS. The invention provides a TOPSIS-based comprehensive benefit evaluation method for a water-wind-light-hydrogen multi-energy complementary off-grid system, and solves the problem of comprehensively considering the popularization and construction of the water-wind-light-hydrogen multi-energy complementary off-grid system.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated energy systems, and in particular relates to a comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system based on TOPSIS. Background Art

[0002] To further alleviate growing energy demand, there is an urgent need to increase the development and utilization of clean energy. Given the significant mismatch between current electricity consumption habits and the output of renewable energy, research into multi-energy complementary power generation systems is a key approach to addressing the imbalance between supply and demand. Efficiently and safely utilizing clean energy sources such as hydropower, wind power, and solar power has become a pressing challenge.

[0003] Current research on multi-energy complementary off-grid systems focuses primarily on economic and environmental benefits, but rarely examines their social benefits, system reliability, and power production safety. Consequently, a comprehensive and robust evaluation index system has yet to be established. Therefore, establishing a scientific and rational comprehensive benefit evaluation system for multi-energy complementary off-grid systems is urgently needed. This system has both theoretical and practical implications for promoting clean energy consumption in Northwest China's energy bases.

[0004] The optimal operation of a multi-energy complementary off-grid system involves the supply, conversion, and storage of various energy sources and is fundamental to achieving sustainable clean energy development. Unlike other system evaluations, this system aims to promote the integration of clean energy sources such as hydropower, wind power, and solar power. Furthermore, comprehensive benefit assessments consider not only economic benefits but also social and environmental impacts.

[0005] Therefore, in order to more objectively and comprehensively evaluate the relationship between various stakeholders under the operation of multi-energy complementary off-grid systems, it is necessary to construct a scientific and reasonable comprehensive evaluation mechanism to ensure the balanced and coordinated development of multi-energy complementary off-grid systems and further improve the comprehensive efficiency of the system. Summary of the Invention

[0006] In order to solve the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide a comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system based on TOPSIS, so as to solve the problem of promotion and construction of a water-wind-solar-hydrogen multi-energy complementary off-grid system under comprehensive consideration.

[0007] The technical solution adopted in the present invention is:

[0008] The comprehensive benefit evaluation method of the water-wind-solar-hydrogen multi-energy complementary off-grid system based on TOPSIS includes the following steps:

[0009] S1: Identify the evaluation object;

[0010] S2: Clarify the construction principles of the evaluation indicator system;

[0011] S3: Clarify the construction method of comprehensive benefit evaluation indicators for off-grid water-wind-solar-hydrogen storage multi-energy complementary system;

[0012] S4: Determine the multi-level indicator weighting method for the comprehensive benefits of multi-energy complementary off-grid system;

[0013] S5: Calculate and analyze comprehensive benefit evaluation results based on TOPSIS.

[0014] As a preferred solution of the present invention, step S1 specifically comprises: selecting a section of a river basin as an example object, and conducting a comprehensive benefit evaluation and comparative analysis of different operation schemes of the example object based on the constructed comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0015] As a preferred embodiment of the present invention, step S2 is specifically as follows: when selecting the benefit evaluation index, the following principles must be followed:

[0016] S21: Comprehensiveness: When selecting comprehensive benefit evaluation indicators for off-grid hydro-wind-solar-hydrogen multi-energy complementary systems, the evaluation indicators should comprehensively consider the selected evaluation objects from multiple aspects. When constructing the relationships between the indicators, the integrity of the constructed evaluation indicator system should be ensured, and the coupling relationships between the indicators should be fully considered. The evaluation indicators should include all factors that affect the comprehensive benefits of the system.

[0017] S22: Hierarchy: The construction of a comprehensive benefit evaluation index system for a water-wind-solar-hydrogen multi-energy complementary off-grid system can clearly demonstrate the relationship between the upper and lower indicators, and the logical relationship between the previous and the next is clear;

[0018] S23: Objectivity: When constructing an evaluation indicator system, if there is any human judgment on the nature of the indicator, it cannot be mixed with subjective will. It is necessary to fully examine the objective historical data of the evaluation indicator based on scientific facts and formulate a more reasonable and objective evaluation indicator system based on this;

[0019] S24: Scientificity: When constructing a comprehensive benefit evaluation index system, it is necessary to comprehensively consider the numerous factors that influence each other among the indicators, respect objective facts, and have a scientific basis when selecting; after selecting the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system, it is also necessary to scientifically explain the definition of each indicator, and at the same time, use scientific methods in the process of obtaining data to ensure that the data calculation is accurate and reliable.

[0020] As a preferred solution of the present invention, step S3 is specifically as follows: the comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system includes economic benefit evaluation indicators, environmental benefit evaluation indicators, technical reliability evaluation indicators and social benefit evaluation indicators.

[0021] As a preferred solution of the present invention, the economic benefit evaluation index includes the factors of life cycle cost, internal rate of return, and investment payback period;

[0022] Life cycle cost:

[0023] The full life cycle cost of a hydro-wind-solar-hydrogen multi-energy complementary off-grid system can take into account all costs of each device in the system from initial procurement and construction to scrapping and disposal. The specific expression is:

[0024] F IA =F IN +F M (1);

[0025]

[0026]

[0027] Where: F IA is the life cycle cost of the system; F IN is the annual equivalent investment cost of the system; F M The operation and maintenance cost of the system; X i is the annual equivalent investment conversion coefficient of the equipment in the system; I is the unit investment cost of each equipment in the system; c i is the annual equivalent investment cost of the system; S i,equ The optimal capacity of each device designed for the system; α i is the operating cost of the i-th device; P i (t) is the power of the i-th device at time t;

[0028] Internal Rate of Return:

[0029] When the sum of the annual net present values ​​of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system is 0, the internal rate of return of the system can be obtained by the corresponding discount rate. The specific expression is:

[0030]

[0031] Where: CI is the capital inflow of the system in year n; CO is the capital outflow of the system in year n; T is the calculation period of the system; IRR is the internal rate of return of the system;

[0032] Payback period:

[0033] From a time perspective, the investment years that the project's economic income can cover are characterized by two indicators: static payback period and dynamic payback period. The specific expression is:

[0034]

[0035] Where: T DPP T is the dynamic investment payback period of the system equipment; APP A is the static investment payback period of the system equipment; cin (n) is the comprehensive income in the nth year; A count (n) is the total investment in year n; r is the annual interest rate.

[0036] As a preferred solution of the present invention, the environmental benefit assessment index examines the impact of the water-wind-solar-hydrogen multi-energy complementary off-grid system on the external environment, including equivalent environmental cost, carbon dioxide emission reduction rate, and space occupancy rate;

[0037] Equivalent environmental cost:

[0038] The pollutant emission coefficients of each energy device in the integrated energy system and the environmental evaluation standards for pollutant gases in the traditional power industry are specifically expressed as follows:

[0039]

[0040] Where: P ex is the amount of thermal power generated by the system; c is the emission coefficient of Class C pollutants; V C The environmental value of Class C pollutants; The amount of fines required for Category C pollutants;

[0041] Carbon dioxide emission reduction rate:

[0042] The carbon emissions from building a multi-energy complementary off-grid system mainly come from the power generation emissions from the gas turbines used in the system. The specific expression is:

[0043]

[0044] Where: is the carbon dioxide emission of the system; ω grid W is the CO2 conversion coefficient of the purchased fossil energy power generation; grid (t) is the electricity generated by fossil energy at time t;

[0045] The CO2 emission reduction rate of the water-wind-solar-hydrogen multi-energy complementary off-grid system is expressed as:

[0046]

[0047] Where: is the CO2 emission reduction rate of the system; is the CO2 emission of traditional distributed power generation system;

[0048] Space occupancy:

[0049] The spatial occupancy rate refers to the fact that the energy generation equipment and energy storage equipment of each subsystem in the water-wind-solar-hydrogen multi-energy complementary off-grid system need to occupy a certain amount of land area.

[0050] As a preferred solution of the present invention, the technical reliability evaluation index is specifically:

[0051] The technical reliability of the off-grid water-wind-solar-hydrogen multi-energy complementary system was evaluated from four perspectives: new energy utilization rate, power supply guarantee rate, power production safety, and system operation flexibility.

[0052] New energy utilization rate:

[0053] The energy and power system planning scheme is the ratio of the average annual renewable energy power generation to the total power generation of the system, which is expressed as:

[0054]

[0055] Where p is the utilization rate of new energy; W r is the renewable energy power generation absorbed; W is the total power generation of the power system;

[0056] Power supply security rate ASAI:

[0057] The ratio of the total number of hours without power outages to the total power supply hours required by users in a year is expressed as:

[0058]

[0059] Where: U i is the annual power outage time of load point i; N i is the total number of load points;

[0060] Safety of power production:

[0061] The safety of power production in a hydro-wind-solar-hydrogen multi-energy complementary off-grid system is primarily considered from two perspectives: the safety of the production equipment within the system and the safety of employees working within the system. Power production safety is a prerequisite for ensuring the stable and reliable operation of the system. A technical assessment of its power production safety examines the system's operational reliability from a technical perspective.

[0062] System operation flexibility:

[0063] Set the system power capacity S P, the maximum regulation capacity S of the interconnection transmission line W And the energy storage device capacity S S and the system maximum load P L,max The ratio of is defined as the operational flexibility of the system, and the specific expression is:

[0064]

[0065] Where: S P It is the power capacity that can be flexibly adjusted within the system; S S is the capacity of the energy storage device in the system; S W is the maximum regulation capacity of the interconnection transmission line; P L,max is the peak power of the system's internal load.

[0066] As a preferred solution of the present invention, social benefit evaluation indicators include providing employment, improving residents' satisfaction, and driving the development of local regional economic industries.

[0067] As a preferred solution of the present invention, step S4 specifically comprises: weighting the evaluation indicators based on a subjective and objective weighting method combining the analytic hierarchy process and the anti-entropy method, and determining the weight coefficients of different indicators.

[0068] As a preferred embodiment of the present invention, step S5 is specifically as follows:

[0069] Based on the weight values ​​of the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system, the TOPSIS method is used to evaluate the comprehensive benefits of each operation scheme for this goal. The specific calculation steps are as follows:

[0070] S51: Weighting the standardized raw data of each evaluation indicator of the comprehensive benefit evaluation of the water-wind-solar-hydrogen multi-energy complementary off-grid system to obtain a weighted matrix, specifically:

[0071]

[0072] Where: P mn Standardized data for each evaluation indicator of system comprehensive benefit evaluation; n is the weight of the nth operation scheme; n is the number of operation schemes of the water-wind-solar-hydrogen multi-energy complementary off-grid system; m is the number of comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system;

[0073] S52: Determine the positive and negative ideal points of the comprehensive benefit evaluation indicators of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system, specifically:

[0074]

[0075] Where: is the set of positive ideal solutions; is the set of negative ideal solutions; J1 is the set of benefit indicators; J2 is the set of cost indicators;

[0076] S53: Calculate the Euclidean distance, specifically:

[0077]

[0078] Where: is the distance from the running plan to the positive ideal point; is the distance from the running solution to the negative ideal point;

[0079] S54: Calculate the relative closeness of each operation scheme of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system, specifically:

[0080]

[0081] Where: C i is the relative closeness of each operation plan, and satisfies 0≤C i ≤1.

[0082] The beneficial effects of the present invention are:

[0083] The present invention proposes a comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system based on TOPSIS. The proposed comprehensive benefit evaluation method involves four aspects: economic benefits, technical reliability, social reliability and environmental benefits. Existing comprehensive benefit evaluation technologies mainly analyze the economic and environmental benefits of multi-energy complementary systems, and rarely involve social benefits such as providing employment and improving residents' satisfaction. At the same time, there is a lack of research on the reliability of system operation and the safety of power production.

[0084] Existing benefit evaluation methods are usually applied to grid-connected multi-energy complementary off-grid systems. The evaluation analysis of off-grid systems is not yet mature. The present invention deeply analyzes the operating mechanism of off-grid systems and then forms a comprehensive benefit evaluation method suitable for multi-energy complementary off-grid systems.

[0085] In view of the fact that there are many evaluation indicators and open value ranges in the comprehensive benefit evaluation of this system, the present invention designs corresponding standardization strategies according to the different characteristics of the evaluation indicators. Subsequently, the evaluation indicators are weighted based on the subjective and objective weighting method combined with the hierarchical analysis method and the anti-entropy method, and the weight coefficients of different indicators are determined. Finally, based on the TOPSIS comprehensive evaluation method, the comprehensive benefit evaluation under different operating schemes in the capacity optimization configuration of the water-wind-solar-hydrogen multi-energy complementary off-grid system is completed, so as to more intuitively and comprehensively evaluate the advantages and disadvantages of different operating schemes. It provides theoretical guidance and decision-making support for the further promotion and construction of the subsequent water-wind-solar-hydrogen multi-energy complementary off-grid system. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 is a flow chart of the method of the present invention;

[0087] Figure 2 It is a system diagram of comprehensive benefit evaluation indicators;

[0088] Figure 3 It is a hierarchical diagram;

[0089] Figure 4 It is a diagram of the multi-level indicator weighting model based on AHP-AEM comprehensive benefits;

[0090] Figure 5 This is a diagram of the water-wind-light-hydrogen multi-energy complementary comprehensive benefit evaluation index system of the present invention. DETAILED DESCRIPTION

[0091] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0092] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features therein may be combined with each other unless there is a conflict.

[0093] like Figure 1 As shown, the comprehensive benefit evaluation method of the water-wind-solar-hydrogen multi-energy complementary off-grid system based on TOPSIS in this embodiment includes the following steps:

[0094] S1: Identify the evaluation object;

[0095] S2: Clarify the construction principles of the evaluation indicator system;

[0096] S3: Clarify the construction method of comprehensive benefit evaluation indicators for off-grid water-wind-solar-hydrogen storage multi-energy complementary system;

[0097] S4: Determine the multi-level indicator weighting method for the comprehensive benefits of multi-energy complementary off-grid system;

[0098] S5: Calculate and analyze comprehensive benefit evaluation results based on TOPSIS.

[0099] For step S1: clarify the evaluation object. Specifically:

[0100] Taking into account the distribution issues of various stakeholders in the water-wind-solar-hydrogen multi-energy complementary off-grid system, a multi-level evaluation index system for comprehensive benefits is constructed for the water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0101] A basin in the upper reaches of the Yellow River was selected as the example object of this study. The area has rich wind and solar resources, so it is suitable for supporting wind power, photovoltaic and hydrogen storage equipment in the area.

[0102] Based on the constructed comprehensive benefit evaluation index system of water-wind-solar-hydrogen multi-energy complementary off-grid system, a comprehensive benefit evaluation and comparative analysis of different operation schemes of the example object are carried out.

[0103] For step S2: clarify the construction principles of the evaluation index system. Specifically:

[0104] When selecting benefit evaluation indicators, the following principles must be followed:

[0105] (1) Comprehensiveness: When selecting comprehensive benefit evaluation indicators for a hydro-wind-solar-hydrogen multi-energy complementary off-grid system, the evaluation indicators must comprehensively consider the selected evaluation object from multiple aspects. At the same time, when constructing the relationship between the indicators, the integrity of the constructed evaluation indicator system must be ensured, and the coupling relationship between the indicators must be fully considered. At the same time, the evaluation indicators should include all factors that affect the comprehensive benefits of the system, so that a comprehensive evaluation can be carried out from multiple perspectives.

[0106] (2) Hierarchy: The construction of a comprehensive benefit evaluation index system for a water-wind-solar-hydrogen multi-energy complementary off-grid system should be able to clearly display the relationship between the upper and lower indicators and whether the logical relationship between the front and back is clear. Therefore, when constructing the index system, try to choose an indicator structure with a front-to-back hierarchy.

[0107] (3) Objectivity: In the constructed evaluation index system, if there is artificial determination of the nature of the indicators, it cannot be mixed with one's own subjective will. It is necessary to fully examine the objective historical data of the evaluation indicators based on scientific facts and formulate a more reasonable objective evaluation index system based on this.

[0108] (4) Scientificity: When constructing a comprehensive benefit evaluation index system, although it is necessary to comprehensively consider the many factors that influence each other among the indicators, it is also necessary to respect objective facts and have a certain scientific basis when selecting indicators to ensure the scientific nature of the indicator selection. After selecting the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system, it is also necessary to scientifically explain the definition of each indicator. At the same time, scientific methods must be used in the process of obtaining data to ensure that the data calculation is accurate and reliable.

[0109] For step S3: clarify the construction method of comprehensive benefit evaluation index of water-wind-solar-hydrogen storage multi-energy complementary off-grid system. Specifically:

[0110] The comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system includes 1 target layer, 4 criterion layers, and 13 connotation indicator layers. Figure 2 shown.

[0111] (1) Economic benefit evaluation indicators:

[0112] The economic benefit evaluation indicators of the constructed water-wind-solar-hydrogen multi-energy complementary off-grid system are mainly to conduct a comprehensive investigation of the economic performance of the system, mainly including the three aspects of full life cycle cost, internal rate of return, and investment payback period.

[0113] 1) Full life cycle cost: From the initial planning and design to the subsequent operation of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system, there are many subsystems and equipment. The full life cycle cost can take into account all the costs of each equipment in the system from initial procurement and construction to scrapping and disposal. The specific expressions are shown in the following equations (1) to (4):

[0114] F IA =F IN +F M (1);

[0115]

[0116] Where: F IA is the life cycle cost of the system; F IN is the annual equivalent investment cost of the system; F M The operation and maintenance cost of the system; X iis the annual equivalent investment conversion coefficient of the equipment in the system; I is the unit investment cost of each equipment in the system; c i is the annual equivalent investment cost of the system; S i,equ The optimal capacity of each device designed for the system; α i is the operating cost of the i-th device; P i (t) is the power of the i-th device at time t.

[0117] 2) Internal rate of return: When the sum of the annual net present values ​​of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system is 0, the internal rate of return of the system can be obtained by applying the corresponding discount rate, as shown in the following formula (1-5):

[0118]

[0119] Where: CI is the capital inflow of the system in year n; CO is the capital outflow of the system in year n; T is the calculation period of the system; IRR is the internal rate of return of the system.

[0120] 3) Payback period: From a time perspective, it represents the number of years that the project's economic income can cover. It can be divided into two indicators: static payback period and dynamic payback period. The specific expressions are shown in the following formulas (6) and (7):

[0121]

[0122] Where: T DPP T is the dynamic investment payback period of the system equipment; APP A is the static investment payback period of the system equipment; cin (n) is the comprehensive income in the nth year; A count (n) is the total investment in year n; r is the annual interest rate.

[0123] (2) Environmental benefit assessment indicators:

[0124] The environmental benefit assessment indicators mainly examine the impact of the water-wind-solar-hydrogen multi-energy complementary off-grid system on the external environment, mainly including three aspects: equivalent environmental cost, carbon dioxide emission reduction rate, and space occupancy rate.

[0125] 1) Equivalent environmental cost: The pollutant emission coefficients of each energy device in the integrated energy system and the environmental evaluation standards for pollutant gases in the traditional power industry are shown in Tables 1 and 2 below, and are specifically expressed as shown in the following formula (8):

[0126]

[0127] Where: P ex is the amount of thermal power generated by the system; cis the emission coefficient of Class C pollutants; V C The environmental value of Class C pollutants; The amount of fines required for Class C pollutants.

[0128] Table 1 Pollutant emission coefficients of different energy equipment

[0129]

[0130] Table 2 Environmental evaluation standards for pollutant gases in traditional power industry

[0131]

[0132] 2) Carbon dioxide emission reduction rate: The carbon emissions from building a multi-energy complementary off-grid system mainly come from the emissions from power generation by gas turbines and other equipment used in the system, which can be specifically expressed as shown in the following formula (9):

[0133]

[0134] Where: is the carbon dioxide emission of the system; ω grid W is the CO2 conversion coefficient of the purchased fossil energy power generation; grid (t) is the fossil energy power generation at time t.

[0135] The CO2 emission reduction rate of the water-wind-solar-hydrogen multi-energy complementary off-grid system is shown in the following formula (10):

[0136]

[0137] Where: is the CO2 emission reduction rate of the system; is the CO2 emissions of traditional distributed power generation systems.

[0138] 3) Space occupancy: Space occupancy refers to the fact that the energy generation equipment and energy storage equipment of each subsystem in the water-wind-solar-hydrogen multi-energy complementary off-grid system need to occupy a certain amount of land area, which will have a certain impact on the external environment. The difference in the number of equipment used under different operating plans will also cause different space occupancy rates, which also reflects the difference in the impact of the system on the environment.

[0139] (3) Technical reliability evaluation indicators:

[0140] When constructing the water-wind-solar-hydrogen multi-energy complementary off-grid system, a technical reliability assessment is required, which will help to discover the technical defects within the system and promote the continuous improvement and development of the water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0141] The technical reliability of the water-wind-solar-hydrogen multi-energy complementary off-grid system is mainly evaluated from four perspectives: new energy utilization rate, power supply guarantee rate, power production safety and system operation flexibility.

[0142] 1) New energy utilization rate: The ratio of the average annual new energy power generation in the energy and power system planning scheme to the total power generation of the system, which is expressed as:

[0143]

[0144] Where p is the utilization rate of new energy; W r is the renewable energy power generation absorbed; W is the total power generation of the power system.

[0145] 2) Power supply assurance rate ASAI: The ratio of the total number of hours of uninterrupted power supply to the total power supply hours required by users in a year. The expression is:

[0146]

[0147] Where: U i is the annual power outage time of load point i; N i is the total number of load points.

[0148] 3) Safety of power production: The safety of power production in the water-wind-solar-hydrogen multi-energy complementary off-grid system is mainly considered from two perspectives: the safety of the production equipment within the system and the safety of employees working in the system. The safety of power production is the prerequisite for ensuring the stable and reliable operation of the system. Therefore, conducting a technical assessment of the safety of its power production is to examine the operational reliability of the system from a technical perspective.

[0149] 4) System operation flexibility: We set the system power capacity S P , the maximum regulation capacity S of the interconnection transmission line W And the energy storage device capacity S S and the system maximum load P L,max The ratio of is defined as the operational flexibility of the system, which is specifically expressed as shown in the following formula (13):

[0150]

[0151] Where: S P It is the power capacity that can be flexibly adjusted within the system; S S is the capacity of the energy storage device in the system; S W is the maximum regulation capacity of the interconnection transmission line; P L,max is the peak power of the system's internal load.

[0152] (4) Social benefit evaluation indicators:

[0153] The implementation of the water-wind-solar-hydrogen multi-energy complementary off-grid system project can not only promote local economic growth, but also promote the reemployment of local residents, thereby improving the quality of life of local people, increasing residents' satisfaction with it, and achieving good social benefits.

[0154] 1) Number of jobs provided: How to improve the national employment rate is also a social issue worthy of attention. After the project is implemented, it will provide a certain number of jobs for local residents. Therefore, the number of jobs provided after the implementation of the project has also become one of the evaluation indicators for examining the social benefits of the water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0155] 2) Improving Resident Satisfaction: The primary purpose of building this off-grid, hydro-wind-solar-hydrogen multi-energy system is to provide clean and stable electricity to the local community, improving the reliability of local electricity use while protecting the environment. After the project is implemented, local residents' satisfaction with the results is crucial. Higher levels of satisfaction indicate greater social benefits for the project. Therefore, resident satisfaction has become a key indicator of the system's social impact.

[0156] 3) Promote the development of local regional economic and industrial development: The main purpose of promoting the development of local economic and industrial development is to improve the local economic environment and promote the development of local related industrial chains after the completion of the water-wind-light-hydrogen multi-energy complementary off-grid system project. Since the system includes a hydrogen storage subsystem, after the implementation of the project, it can greatly promote the development of the local hydrogen energy industry, including hydrogen storage, manufacturing, transportation, etc. At the same time, with the support of national policies, it also provides a forward-looking platform for related clean energy power generation industries. The stronger the demonstration and driving effect of the project on advanced technologies, the more it can promote the development of related industrial chains and have strong social benefits. Therefore, promoting the development of local regional economic and industrial development has also become an important indicator for measuring the social benefits after the implementation of the system.

[0157] For step S4: determine the multi-level index weighting method for the comprehensive benefits of the multi-energy complementary off-grid system. Specifically:

[0158] The subjective and objective weighting method based on the combination of hierarchical analysis method and anti-entropy method is used to weight the evaluation indicators and determine the weight coefficients of different indicators.

[0159] (1) Analytical Hierarchy Process:

[0160] The Analytic Hierarchy Process (AHP) is a widely used method for calculating subjective weights. When faced with complex decision-making problems, it transforms subjective understanding into mathematical analysis by constructing an AHP model, decomposing and simplifying the complex problem. The importance of each indicator is then determined through pairwise comparisons, ultimately yielding the subjective weight of the objective.

[0161] The specific calculation steps are as follows:

[0162] 1) Establish a hierarchical structure: clarify the research object, stratify it according to the relationship between each indicator, and establish a hierarchical structure, as follows Figure 3 shown.

[0163] 2) Construct interval judgment matrix

[0164] After determining the interrelationships between the target layer, criterion layer, and indicator layer, an interval judgment matrix can be established. Using the judgment matrix scaling method as a criterion, as shown in Table 3 below, the importance of indicators at the same level can be compared pairwise using other factors, resulting in a judgment matrix:

[0165]

[0166] Where: a ij Considering certain factors, U i with U j the relative importance of is the upper limit of the result; The lower limit of the result.

[0167] At the same time, the judgment matrix should have the following properties: a ij >0; a ii =1.

[0168] Table 3 Explanation of judgment matrix scaling method

[0169] <![CDATA[Scale a ij > meaning 1 <![CDATA[U i with U j of equal importance]]> 3 <![CDATA[U i with U j In comparison, U i The importance of U is slightly higher than j ]]> 5 <![CDATA[U i with U j In comparison, U i The importance of U j ]]> 7 <![CDATA[U i with U j In comparison, U i The importance of U is much higher than j ]]> 9 <![CDATA[U i with U j In comparison, U i The importance of U is much higher than j ]]> 2、4、6、8 <![CDATA[U i with U j The importance of the two is between the adjacent odd numbers]]>

[0170] 3) Solution of indicator weights:

[0171] First, the weight vector of the indicator set is calculated through the judgment matrix A and normalized, as shown in the following formula (15):

[0172]

[0173] Then, each row of the normalized judgment matrix A is further summed to obtain the sum value M of each row of A. i

[0174]

[0175] Finally, find the indicator weight ω of each indicator of A i

[0176]

[0177] 4) Perform consistency check:

[0178] Since the judgment matrix A is obtained by comparing two by two, U j The importance of U i This is an incorrect judgment logic. If the judgment matrix cannot meet the consistency requirements, the solution will be unable to proceed, so it is necessary to check its consistency.

[0179] The consistency index CI meets the following requirements:

[0180]

[0181] The random consistency ratio CR of the judgment matrix A satisfies:

[0182]

[0183] Where: max is the maximum eigenvalue of the judgment matrix A; n is the order of the judgment matrix; R1 is the average random consistency index.

[0184] R1 varies with the index order n. See Table 4 for specific values. If the random consistency ratio CR of judgment matrix A satisfies CR less than 0.1, it is considered that judgment matrix A meets the consistency condition. If CR is greater than or equal to 0.1, it should be modified until the consistency condition is met.

[0185] Table 4 Values ​​of R1

[0186] n R1 n R1 n R1 1 0 5 1.09 9 1.49 2 0 6 1.26 10 1.56 3 0.54 7 1.31 11 1.59 4 0.91 8 1.43 12 1.64

[0187] 5) Overall weight calculation: If the obtained matrices all meet the consistency check, the overall weight can be calculated after calculating the weight of each layer.

[0188] (2) Anti-entropy method:

[0189] The traditional entropy weight method has the problem of excessive disorder sensitivity in the weight assignment process, which leads to extreme weights in the evaluation results. In order to avoid this situation as much as possible, an anti-entropy method (Anti-Entropy Method, AEM) based on entropy value is defined as shown in the following formula (20):

[0190]

[0191] Where: 0≤K i ≤1, and h i It has the opposite characteristics to h. The greater the disorder of the system, the greater the anti-entropy.

[0192] The objective weight vector W”=(w”1,w”2,…,w” is calculated by using the anti-entropy method. s ).w” i The calculation of is shown in the following formula (21):

[0193]

[0194] 1) According to the comprehensive benefit evaluation index system of water-wind-solar-hydrogen multi-energy complementary off-grid system, the target decision matrix A' is obtained, where A' = (x ij )(i=1,2,....,m,j=1,2,....,n) is shown in the following formula (22):

[0195]

[0196] Where: n is the number of operation schemes of the water-wind-solar-hydrogen multi-energy complementary off-grid system; m is the number of comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system; x ij is the original value of the jth indicator in the i-th optimization strategy.

[0197] 2) The comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system is unified. In order to facilitate calculation, the cost type of the index type is converted into the benefit type. The specific processing method is as follows (23):

[0198]

[0199] After the conversion is completed, the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system are standardized and calculated:

[0200]

[0201] Where: P ij Standardized data for various evaluation indicators of the comprehensive benefit evaluation of the water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0202] 3) The entropy value of the comprehensive benefit evaluation index of the j-th water-wind-solar-hydrogen multi-energy complementary off-grid system is calculated by calculation, as shown in the following formula (25):

[0203]

[0204] Where: e j is the entropy value of the comprehensive benefit evaluation index of the j-th water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0205] 4) Calculate the difference coefficient of the comprehensive benefit evaluation index of the j-th cascade basin water-wind-solar-hydrogen multi-energy complementary off-grid system, as shown in the following formula (26):

[0206] g j =1-e j (26);

[0207] 5) Calculate the weights of comprehensive benefit evaluation indicators for the off-grid water-wind-solar-hydrogen multi-energy complementary system in the cascade basin, as shown in the following formula (27):

[0208]

[0209] Where: ω j ——The weight value of the jth comprehensive benefit evaluation index of the water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0210] (3) Classification quantification and fuzzy algorithm normalization processing:

[0211] The comprehensive benefit evaluation indicators of the constructed water-wind-solar-hydrogen multi-energy complementary off-grid system are divided into three types: those with specific numerical restrictions, those with fixed lower limits and no upper limits, and those with lower limits and no upper limits for maximum optimal saturation. They are then fuzzified using membership functions and divided into two categories: cost type and benefit type according to the fuzzy algorithm.

[0212] Generally, the values ​​with specific numerical limits are set between 0 and 1, while the fixed lower limit of the fixed lower limit and no upper limit is set to 0. The normalization transformation is performed as shown in the following formula (28):

[0213]

[0214] For the maximum optimization saturation with a lower limit but no upper limit, there is generally no clear limit on its upper limit. However, when it is greater than 1, a piecewise function can be used to enclose it and quantize it around 1. The specific expression is shown in the following formula (29):

[0215]

[0216] After classifying the various sub-indicators of the comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system into the above three types, the membership function μ(x) is used to perform fuzzy processing, where μ(x)∈[0,1]. Since the indicators are divided into two categories: benefit type and cost type, when the indicator k in the evaluation index layer of the comprehensive benefit of the multi-energy complementary off-grid system belongs to the benefit type indicator, the membership function μ kThe specific expression of (x) is shown in the following formula (30):

[0217]

[0218] When the indicator k in the evaluation index layer of the comprehensive benefit of the multi-energy complementary off-grid system belongs to the cost-type indicator, the membership function μ k The specific expression of (x) is shown in the following formula (31):

[0219]

[0220] Where: f k,min is the minimum value of the evaluation index k; f k,max is the maximum value of the evaluation index k.

[0221] After obtaining μ(x), we can perform weighted summation on it to obtain the index optimization function of the comprehensive benefit evaluation system of the water-wind-solar-hydrogen multi-energy complementary off-grid system:

[0222]

[0223] Where G k is the weight coefficient of each indicator in the comprehensive benefit evaluation index system of the system; and satisfies G k ≥0,

[0224] (4) Combined weight calculation based on analytic hierarchy process and anti-entropy method:

[0225] The analytic hierarchy process (AHP) and anti-entropy weight (AEM) method are combined to form a subjective and objective weighting method. The subjective and objective weighting method is used to determine the combination weights, and a multi-level indicator weighting model for the comprehensive benefits of the water-wind-solar-hydrogen multi-energy complementary off-grid system based on the analytic hierarchy process and anti-entropy weight method is established. The specific indicator weighting model is as follows Figure 4 shown.

[0226] The calculation steps of the subjective and objective weighting method based on AHP-AEM are as follows:

[0227] 1) Constructing the evaluation index set: Determine the comprehensive benefit evaluation index set U = {u1,u2,…,u nThe first-level indicators are composed of four criteria layers, including economic benefit assessment indicators, environmental benefit assessment indicators, technical reliability assessment indicators, and social benefit assessment indicators. The second-level indicators are composed of 13 connotation indicator layers, including full life cycle cost, internal rate of return, investment payback period, equivalent environmental cost, CO2 emission reduction rate, space occupancy rate, new energy utilization rate, power supply guarantee rate, power production safety, system operation flexibility, number of jobs provided, resident satisfaction, and promotion of regional economic development.

[0228] 2) Determine the review set V = {v1, v2, ..., v n}.

[0229] 3) Determine the indicator weights of the indicator system based on AHP: First, construct the judgment matrix A, and use the U i with U j The relative importance of a ij , construct the judgment matrix A, specifically see the above formula (1-18). Calculate the weight vector of the indicator set through the judgment matrix A and normalize it, specifically see the above formula (1-19). Then, further sum each row of the normalized judgment matrix A to obtain the sum value M of each row of A. i , see the above formula (1-20) for details. Then, find the subjective weight ω of each indicator in the indicator set j See the above formula (1-21) for details.

[0230] Finally, a consistency test is performed. For details, see (1-22) and (1-23) in the above AHP.

[0231] 4) Determine the indicator weights of the indicator system based on AEM: Calculate the entropy value between the system evaluation indicators to obtain the indicator weights ω of AEM j , for specific calculations, see the solution process of the anti-entropy method above.

[0232] 5) Calculation of combined weight coefficient: After obtaining the above two weight values, the combined weight coefficient of the two weights is determined based on AHP and AEM. The specific calculation formula is shown in the following formula (33):

[0233]

[0234] Where: ε i is the weight coefficient of AHP; δ i is the weight coefficient of AEM.

[0235] 6) Final solution of combination weight: Finally, the final combination weight value ω is obtained through combination calculation i :

[0236]

[0237] For step 5: Calculate and analyze the comprehensive benefit evaluation results based on TOPSIS. Specifically:

[0238] Based on the weight values ​​of the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system, the TOPSIS method is used to evaluate the comprehensive benefits of each operation scheme for this goal. The specific calculation steps are as follows:

[0239] (1) The standardized raw data of each evaluation index of the comprehensive benefit evaluation of the water-wind-solar-hydrogen multi-energy complementary off-grid system are weighted to obtain a weighted matrix, as shown in the following formula (35):

[0240]

[0241] Where: P mn Standardized data for each evaluation indicator of system comprehensive benefit evaluation; n is the weight of the nth operation scheme; n is the number of operation schemes of the water-wind-solar-hydrogen multi-energy complementary off-grid system; m is the number of comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system.

[0242] (2) Determine the positive and negative ideal points of the comprehensive benefit evaluation index of the water-wind-solar-hydrogen multi-energy complementary off-grid system, as shown in the following equations (36) and (37):

[0243]

[0244] Where: is the set of positive ideal solutions; is a set of negative ideal solutions; J1 is a set of benefit indicators; J2 is a set of cost indicators.

[0245] (3) Calculate the Euclidean distance, as shown in the following equations (38) and (39):

[0246]

[0247] Where: is the distance from the running plan to the positive ideal point; is the distance from the running solution to the negative ideal point.

[0248] (4) Calculate the relative closeness of each operation scheme of the water-wind-solar-hydrogen multi-energy complementary off-grid system. Specifically, it is as follows:

[0249]

[0250] Where: C i is the relative closeness of each operation plan, and satisfies 0≤C i≤1.

[0251] Example:

[0252] A comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system based on TOPSIS includes the following steps:

[0253] Step 1: Identify the evaluation object.

[0254] A basin in the upper reaches of the Yellow River was selected as the example object of this study. The area has rich wind and solar resources, so it is suitable for supporting wind power, photovoltaic and hydrogen storage equipment in the area.

[0255] Based on the constructed comprehensive benefit evaluation index system of water-wind-solar-hydrogen multi-energy complementary off-grid system, a comprehensive benefit evaluation and comparative analysis of different operation schemes of the example object are carried out.

[0256] Operational Option 1: No wind power, photovoltaic power, or hydrogen storage equipment is involved in regulation. Only cascade hydropower operates independently, allowing the cascade hydropower to meet the system's needs as much as possible within certain constraints, thereby reducing external power purchases.

[0257] Operational Scheme 2: Combined hydropower, wind power, and solar power, without hydrogen storage. In this scenario, the constructed two-tier capacity optimization model does not consider the variables and constraints related to hydrogen storage, and only incorporates the constraints of hydropower, wind power, and solar power into the solution.

[0258] Operation plan 3: Based on cascade hydropower stations, wind power plants, solar power plants, and hydrogen storage are combined for operation, and capacity optimization is performed based on a conventional two-layer model.

[0259] Based on the system comprehensive benefit evaluation index system diagram ( Figure 2 ) The relationship between the various indicators in the comprehensive benefit evaluation index system diagram of the water-wind-solar-hydrogen multi-energy complementary off-grid system established a hierarchical structure of indicator evaluation, and analyzed the nature of each indicator from the two aspects of cost, benefit, qualitative and quantitative.

[0260] Quantitative indicator processing: By consulting relevant data and literature for analysis, the three operating plans formulated were sorted and summarized, and the quantitative indicator data of the three operating plans for the comprehensive benefit evaluation of the water-wind-solar-hydrogen multi-energy complementary off-grid system were obtained as shown in Table 5 below:

[0261] Table 5 Quantitative indicators required for comprehensive benefit evaluation of water-wind-solar-hydrogen multi-energy complementary off-grid system

[0262] Evaluation indicator name Run plan 1 Run scenario 2 Run plan 3 Full life cycle cost / 10,000 yuan 68015.4 76974.1 77162.4 Internal rate of return / % 7.25％ 7.98％ 8.91％ Investment payback period / year 14.5 13.9 13.1 Equivalent environmental cost / (10,000 yuan / year) 22.56 24.67 28.94 <![CDATA[CO2 emission reduction amount / (tons / year)]]> 103225.1 147165.1 151623.5 New energy utilization rate / % 90.1 95.3 99.4 Number of people employed 52 58 64 Resident satisfaction / % 82.3 85.6 87.1

[0263] Qualitative indicator processing: Invite relevant industry experts to score the qualitative indicators according to the qualitative indicator evaluation standards shown in Table 6 below on a percentage basis, and use the average value as the reference standard. The resulting qualitative evaluation indicator scores are shown in Table 7 below.

[0264] Table 6 Qualitative evaluation index levels for comprehensive benefit assessment of off-grid water-wind-solar-hydrogen multi-energy complementary systems

[0265] Evaluation level Score range very good [90,100] better [75,90) medium [60,75) Poor [0,60)

[0266] Table 7 Qualitative indicator data for comprehensive benefit evaluation of water-wind-solar-hydrogen multi-energy complementary off-grid system

[0267]

[0268]

[0269] Step 2: Calculate the indicator weights based on the analytic hierarchy process (AHP).

[0270] When calculating indicator weights based on the hierarchical analysis method, the indicator weights of the criterion layer and the indicator layer need to be calculated separately.

[0271] When calculating the weights of indicators at the criterion layer, the judgment matrix of the criterion layer is generally constructed by inviting relevant industry experts to score. From the four dimensions of economic benefit evaluation indicators, environmental benefit evaluation indicators, technical reliability evaluation indicators and social benefit evaluation indicators, the judgment matrix scaling method in Tables 1-3 above is used to calculate the relative importance of the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system by comparing two indicators with each other, thereby constructing an interval judgment matrix. On the basis of meeting the consistency check, the weight values ​​of the evaluation indicators in the matrix are calculated using the above formulas (15)-(17).

[0272] When calculating the indicator weights of the indicator layer, it is necessary to solve the indicator layer corresponding to each criterion layer separately. Taking the solution of economic benefit evaluation indicator B1 as an example, it is necessary to compare the three perspectives of full life cycle cost, internal rate of return and investment environment cycle respectively, to obtain the judgment matrix of economic benefit evaluation indicators, and after meeting the consistency check, calculate the corresponding weight value. Similarly, calculate the indicator weights of the indicator layer of environmental benefit evaluation indicator B2, technical reliability evaluation indicator B3, and social benefit evaluation indicator B4 respectively.

[0273] By multiplying the indicator weights of the criterion layer obtained above with the indicator weights of the indicator layer, the weight of each indicator based on AHP can be obtained.

[0274] Step 3: Calculate indicator weights based on the anti-entropy method (AEM).

[0275] Using the data in Tables 1-6 and 1-8 above, a decision matrix for the indicator layer of the comprehensive benefit evaluation index of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system is constructed according to the above formula (22).

[0276] Then, the comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system is unified. The four cost-type indicators of life cycle cost, investment recovery period, equivalent environmental cost and space occupancy rate are converted into benefit-type indicators through the above formula (23). Then, the indicator data in the indicator layer evaluation index system are standardized and calculated using formula (24).

[0277] Secondly, the entropy value of each evaluation indicator in the comprehensive benefit index layer of the water-wind-solar-hydrogen multi-energy complementary off-grid system is calculated according to the above formula (25). The difference coefficient of each indicator in the comprehensive benefit evaluation index layer of the water-wind-solar-hydrogen multi-energy complementary off-grid system is calculated using the above formula (26).

[0278] Finally, the weight of each evaluation indicator in the comprehensive benefit evaluation index layer of the water-wind-solar-hydrogen multi-energy complementary off-grid system is calculated based on the above formula (27).

[0279] Because it is impossible to directly calculate the indicator weights of the criterion layer, the indicator data of the indicator layer is multiplied by the corresponding weights and then summed up to obtain the indicator data of the criterion layer. Finally, the indicator weights of the criterion layer are calculated based on the anti-entropy method.

[0280] Step 4: Determine the indicator combination weight.

[0281] Using the above formulas (33) and (34), the subjective and objective weighting methods based on AHP-AEM are combined to obtain the final indicator weight value.

[0282] Step 5: Calculation and analysis of comprehensive benefit evaluation results based on TOPSIS.

[0283] (1) Calculate the weighted matrix of comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system: Calculate the weighted matrix of comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system according to the above formula (35).

[0284] (2) Solve the positive and negative ideal points of each indicator: According to formulas (36) and (38), solve the positive and negative ideal points of each indicator.

[0285] (3) Calculate the Euclidean distance:

[0286] The Euclidean distances between each operation scheme and the positive and negative ideal points are calculated using equations (38) and (39), as shown in Table 8 below:

[0287] Table 8 Euclidean distances between each operation scheme and the positive and negative ideal points

[0288] Operation plan name Euclidean distance to the ideal point Euclidean distance to the negative ideal point Run plan 1 0.0314 0.0009 Run scenario 2 0.0267 0.0053 Run plan 3 0.0016 0.0314

[0289] (4) Calculation of relative closeness: Based on the above formula (40), the relative closeness of each operation scheme of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system is calculated, as shown in Table 9 below:

[0290] Table 9 Relative closeness of various operation plans

[0291] Operation plan name Relative closeness Sorting Run plan 1 0.2658 3 Run scenario 2 0.6374 2 Run plan 3 0.8250 1

[0292] As can be seen from the table above, the Euclidean distance to the positive ideal point for Operational Option 1 is 0.0314, and the Euclidean distance to the negative ideal point is 0.0009. Compared with the other two options, it has the longest Euclidean distance to the positive ideal point and the shortest Euclidean distance to the negative ideal point. The calculated relative closeness is 0.2658, the smallest among the three options, and therefore this operation option has the worst evaluation result. Operational Option 3, on the other hand, has a Euclidean distance to the positive ideal point of 0.0016, and a Euclidean distance to the negative ideal point of 0.0314. The calculated relative closeness is 0.8250, the largest among the three options, and therefore, this option has the best overall benefit evaluation.

[0293] Considering that Operational Option 3 combines hydropower, wind power, solar power, and hydrogen, while mitigating the instability of wind and solar power output, the use of hydrogen storage equipment can significantly improve the system's operating returns and clean energy absorption rate. This chapter evaluates the comprehensive benefits of the constructed multi-energy complementary off-grid system from four perspectives: economic, environmental, technical reliability, and social. This verifies the superiority of Operational Option 3 and demonstrates the broad application prospects of hydropower, wind power, solar power, and hydrogen combined operation.

[0294] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that falls within the scope defined by the claims of the present invention falls within the scope of protection of the present invention.

Claims

1. A TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system, characterized by: The following steps are involved: S1: Identify the evaluation object; S2: Clarify the construction principles of the evaluation indicator system; S3: Clarify the construction method of comprehensive benefit evaluation indicators for off-grid water-wind-solar-hydrogen storage multi-energy complementary system; S4: Determine the multi-level indicator weighting method for the comprehensive benefits of multi-energy complementary off-grid system; S5: Calculate and analyze comprehensive benefit evaluation results based on TOPSIS.

2. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 1 is characterized by: Step S1 specifically includes: selecting a section of a river basin as an example object, and conducting a comprehensive benefit evaluation and comparative analysis of different operation plans of the example object based on the constructed comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system.

3. The comprehensive benefit evaluation method of the water-wind-solar-hydrogen multi-energy complementary off-grid system based on TOPSIS according to claim 1 is characterized in that: Step S2 is specifically as follows: When selecting benefit evaluation indicators, the following principles must be followed: S21: Comprehensiveness: When selecting comprehensive benefit evaluation indicators for off-grid hydro-wind-solar-hydrogen multi-energy complementary systems, the evaluation indicators should comprehensively consider the selected evaluation objects from multiple aspects. When constructing the relationships between the indicators, the integrity of the constructed evaluation indicator system should be ensured, and the coupling relationships between the indicators should be fully considered. The evaluation indicators should include all factors that affect the comprehensive benefits of the system. S22: Hierarchy: The construction of a comprehensive benefit evaluation index system for a water-wind-solar-hydrogen multi-energy complementary off-grid system can clearly demonstrate the relationship between the upper and lower indicators, and the logical relationship between the previous and the next is clear; S23: Objectivity: When constructing an evaluation indicator system, if there is any human judgment on the nature of the indicator, it cannot be mixed with subjective will. It is necessary to fully examine the objective historical data of the evaluation indicator based on scientific facts and formulate a more reasonable and objective evaluation indicator system based on this; S24: Scientificity: When constructing a comprehensive benefit evaluation index system, it is necessary to comprehensively consider the numerous factors that influence each other among the indicators, respect objective facts, and have a scientific basis when selecting; after selecting the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system, it is also necessary to scientifically explain the definition of each indicator, and at the same time, use scientific methods in the process of obtaining data to ensure that the data calculation is accurate and reliable.

4. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 1 is characterized by: Step S3 is specifically as follows: the comprehensive benefit evaluation index system of the water-wind-solar-hydrogen multi-energy complementary off-grid system includes economic benefit evaluation indicators, environmental benefit evaluation indicators, technical reliability evaluation indicators and social benefit evaluation indicators.

5. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 4 is characterized by: Factors considered in economic benefit evaluation indicators include life cycle cost, internal rate of return, and payback period; Life cycle cost: The full life cycle cost of a hydro-wind-solar-hydrogen multi-energy complementary off-grid system can take into account all costs of each device in the system from initial procurement and construction to scrapping and disposal. The specific expression is: F IA =F IN +F M (1); Where: F IA is the life cycle cost of the system; F IN is the annual equivalent investment cost of the system; F M The operation and maintenance cost of the system; X i is the annual equivalent investment conversion coefficient of the equipment in the system; I is the unit investment cost of each equipment in the system; c i is the annual equivalent investment cost of the system; S i,equ The optimal capacity of each device designed for the system; α i is the operating cost of the i-th device; P i (t) is the power of the i-th device at time t; Internal Rate of Return: When the sum of the annual net present values ​​of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system is 0, the internal rate of return of the system can be obtained by the corresponding discount rate. The specific expression is: Where: CI is the capital inflow of the system in year n; CO is the capital outflow of the system in year n; T is the calculation period of the system; IRR is the internal rate of return of the system; Payback period: From a time perspective, the investment years that the project's economic income can cover are characterized by two indicators: static payback period and dynamic payback period. The specific expression is: Where: T DPP T is the dynamic investment payback period of the system equipment; APP A is the static investment payback period of the system equipment; cin (n) is the comprehensive income in the nth year; A count (n) is the total investment in year n; r is the annual interest rate.

6. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 4 is characterized by: The environmental benefit assessment index examines the impact of the water-wind-solar-hydrogen multi-energy complementary off-grid system on the external environment, including equivalent environmental costs, carbon dioxide emission reduction rate, and space occupancy rate; Equivalent environmental cost: The pollutant emission coefficients of each energy device in the integrated energy system and the environmental evaluation standards for pollutant gases in the traditional power industry are specifically expressed as follows: Where: P ex is the amount of thermal power generated by the system; c is the emission coefficient of Class C pollutants; V C The environmental value of Class C pollutants; The amount of fines required for Category C pollutants; Carbon dioxide emission reduction rate: The carbon emissions from building a multi-energy complementary off-grid system mainly come from the power generation emissions from the gas turbines used in the system. The specific expression is: Where: is the carbon dioxide emission of the system; ω grid W is the CO2 conversion coefficient of the purchased fossil energy power generation; grid (t) is the electricity generated by fossil energy at time t; The CO2 emission reduction rate of the water-wind-solar-hydrogen multi-energy complementary off-grid system is expressed as: Where: is the CO2 emission reduction rate of the system; is the CO2 emission of traditional distributed power generation system; Space occupancy: The spatial occupancy rate refers to the fact that the energy generation equipment and energy storage equipment of each subsystem in the water-wind-solar-hydrogen multi-energy complementary off-grid system need to occupy a certain amount of land area.

7. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 4 is characterized by: The specific technical reliability evaluation indicators are: The technical reliability of the off-grid water-wind-solar-hydrogen multi-energy complementary system was evaluated from four perspectives: new energy utilization rate, power supply guarantee rate, power production safety, and system operation flexibility. New energy utilization rate: The energy and power system planning scheme is the ratio of the average annual renewable energy power generation to the total power generation of the system, which is expressed as: Where p is the utilization rate of new energy; W r is the renewable energy power generation absorbed; W is the total power generation of the power system; Power supply security rate ASAI: The ratio of the total number of hours without power outages to the total power supply hours required by users in a year is expressed as: Where: U i is the annual power outage time of load point i; N i is the total number of load points; Safety of power production: The safety of power production in a hydro-wind-solar-hydrogen multi-energy complementary off-grid system is primarily considered from two perspectives: the safety of the production equipment within the system and the safety of employees working within the system. Power production safety is a prerequisite for ensuring the stable and reliable operation of the system. A technical assessment of its power production safety examines the system's operational reliability from a technical perspective. System operation flexibility: Set the system power capacity S P , the maximum regulation capacity S of the interconnection transmission line W And the energy storage device capacity S S and the system maximum load P L,max The ratio of is defined as the operational flexibility of the system, and the specific expression is: Where: S P It is the power capacity that can be flexibly adjusted within the system; S S is the capacity of the energy storage device in the system; S W is the maximum regulation capacity of the interconnection transmission line; P L,max is the peak power of the system's internal load.

8. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 4 is characterized by: Social benefit evaluation indicators include providing employment, improving residents' satisfaction, and driving the development of local regional economic industries.

9. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 1, characterized in that: Step S4 is specifically as follows: weighting the evaluation indicators based on the subjective and objective weighting method combined with the hierarchical analysis method and the anti-entropy method, and determining the weight coefficients of different indicators.

10. The TOPSIS-based comprehensive benefit evaluation method for a water-wind-solar-hydrogen multi-energy complementary off-grid system according to claim 1, characterized in that: Step S5 is specifically as follows: Based on the weight values ​​of the comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system, the TOPSIS method is used to evaluate the comprehensive benefits of each operation scheme for this goal. The specific calculation steps are as follows: S51: Weighting the standardized raw data of each evaluation indicator of the comprehensive benefit evaluation of the water-wind-solar-hydrogen multi-energy complementary off-grid system to obtain a weighted matrix, specifically: Where: P mn Standardized data for each evaluation indicator of system comprehensive benefit evaluation; n is the weight of the nth operation scheme; n is the number of operation schemes of the water-wind-solar-hydrogen multi-energy complementary off-grid system; m is the number of comprehensive benefit evaluation indicators of the water-wind-solar-hydrogen multi-energy complementary off-grid system; S52: Determine the positive and negative ideal points of the comprehensive benefit evaluation indicators of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system, specifically: Where: is the set of positive ideal solutions; is the set of negative ideal solutions; J1 is the set of benefit indicators; J2 is the set of cost indicators; S53: Calculate the Euclidean distance, specifically: Where: is the distance from the running plan to the positive ideal point; is the distance from the running solution to the negative ideal point; S54: Calculate the relative closeness of each operation scheme of the hydro-wind-solar-hydrogen multi-energy complementary off-grid system, specifically: Where: C i is the relative closeness of each operation plan, and satisfies 0≤C i ≤1.

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