A method and system for determining the optimal output ratio of wind, solar, and thermal power bundling

Abstract

This invention discloses a method and system for determining the optimal power output ratio scheme of wind-solar-thermal power bundling. The method includes: acquiring basic parameters of a wind-solar-thermal power bundling DC transmission system under different power output ratios of wind, solar, and thermal power; calculating safety and economic indicators for different ratio schemes based on the acquired basic parameters; ranking the safety and economic indicators of different ratio schemes using a preset VIKOR evaluation model to obtain the optimal scheme; and outputting the optimal power output ratio of the wind-solar-thermal power bundling DC transmission system based on the power output ratios of wind, solar, and thermal power in the optimal scheme. This invention comprehensively evaluates multiple ratio schemes using the VIKOR evaluation model, enabling the selection of the optimal wind-solar-thermal power bundling scheme.

Description

Technical Field

[0001] This invention relates to a method and system for determining the optimal output ratio scheme of wind, solar and thermal power bundling, belonging to the field of power system stability control. Background Technology

[0002] In my country, large-scale wind and solar power bases are mainly distributed in the north, west, and eastern coastal areas, while thermal power bases are also mainly concentrated in the "Three Norths" region (Northeast, North, and Northwest my country). Due to the significant overlap in the distribution areas of these three energy sources, and given the objective reality of the inverse distribution of energy distribution and energy demand in China, there is an objective need for large-scale, long-distance transmission of wind, solar, and thermal energy to load centers. DC transmission technology has significant advantages over AC transmission in terms of large-capacity, long-distance transmission. For this reason, many scholars have begun to consider using DC transmission systems to transmit bundled wind and thermal power energy. Bundling wind and solar power with nearby thermal power plants can greatly improve the system's power output fluctuations by leveraging the complementarity of wind and solar energy and the controllability of thermal power generation, thereby increasing the stability of the DC transmission channel's power output, ensuring the reliability of the DC transmission system, and significantly improving the utilization rate of the DC transmission channel. Simultaneously, the coordinated control between the DC transmission system and various power sources can improve the safety and stability of the bundled wind-solar-thermal AC / DC transmission system.

[0003] Studies have shown that the ratio of wind and solar power connected to the grid affects the power angle stability of the system. Therefore, in the process of bundling wind, solar and thermal power for transmission, maintaining an appropriate ratio of wind, solar and thermal power connected to the grid is of vital importance to the safe and stable operation of the power grid. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method and system for determining the optimal power output ratio of wind-solar-thermal baling. By comprehensively evaluating multiple ratio schemes using the VIKOR evaluation model, the optimal wind-solar-thermal baling ratio can be selected. To achieve the above objective, this invention employs the following technical solution:

[0005] In a first aspect, the present invention provides a method for determining the optimal power output ratio scheme for wind, solar, and thermal baling, including:

[0006] Obtain the basic parameters of the wind-thermal bundled DC transmission system under different schemes with varying wind power, photovoltaic power, and thermal power output ratios;

[0007] Based on the obtained basic parameters, calculate the safety and economic indicators of different proportion schemes;

[0008] Using the pre-set VIKOR evaluation model, the safety and economic indicators of different proportion schemes are ranked to obtain the optimal scheme.

[0009] Based on the ratio of wind power output, photovoltaic power output, and thermal power output in the optimal scheme, the optimal output ratio of the wind-thermal bundled DC transmission system is output.

[0010] In conjunction with the first aspect, the safety indicators further include: system acceleration energy indicator, maximum voltage deviation of key nodes indicator, and maximum power angle indicator.

[0011] In conjunction with the first aspect, optionally, the system acceleration energy index is expressed by the following formula:

[0012] (1)

[0013] In equation (1), E acc P represents the system's acceleration energy index. m P represents the mechanical power of the generator. e δ represents the generator's electromagnetic power; δ is the generator's power angle.

[0014] In conjunction with the first aspect, optionally, the maximum deviation of the key node voltage index is expressed by the following formula:

[0015] (2)

[0016] In equation (2), ΔU represents the maximum voltage deviation index of the critical node, and U represents the actual voltage value of the bus node; U N This refers to the rated voltage of the busbar node.

[0017] In conjunction with the first aspect, optionally, the maximum power angle index is expressed by the following formula:

[0018] (3)

[0019] In equation (3), δ θ θ represents the maximum power angle index. i θ represents the power angle of a thermal power unit during a transient process. N Indicates the power angle of the reference unit.

[0020] In conjunction with the first aspect, the economic indicators further include the energy cost (LCOE) indicator.

[0021] In conjunction with the first aspect, optionally, the energy cost LCOE index is expressed by the following formula:

[0022] (4)

[0023] In equation (4), P n The LCOE (Levelized Cost of Energy) indicator, C n B represents the total expenditure in year n. n Let A represent income from other sources in year n.n Let r represent the electrical energy produced in year n, and r represent the discount rate.

[0024] In conjunction with the first aspect, the optimal solution is further described as follows:

[0025] Initialize each different ratio scheme as alternative scheme A i (i=1,2,…,n);

[0026] Based on the safety and economic indicators of the alternative solutions, the optimal and worst evaluation values ​​of the alternative solutions are calculated using the evaluation criteria of the preset VIKOR evaluation model.

[0027] Based on the calculated optimal and worst evaluation values, the S-value of the pre-defined VIKOR evaluation model is calculated. i and R i S was obtained from the calculation. i and R i Calculate Q i ;

[0028] According to Q i The values ​​are incremented, and the candidate solutions are sorted to obtain a sequence A of candidate solutions. (1) A (2) A (J) A (n) ;

[0029] The first alternative A in the output sequence (1) This is the optimal solution.

[0030] In conjunction with the first aspect, further, the calculation of the optimal and worst evaluation values ​​of the alternative solutions includes:

[0031] The evaluation criterion of the preset VIKOR evaluation model is C. j (j=1,2,…,m), then alternative solution A i The evaluation value of (i=1,2,…,n) is f ij ;

[0032] When evaluation criterion C j When using a benefit-based criterion, ,

[0033] When evaluation criterion C j When using a cost-based criterion, ,

[0034] Among them, f j * For the optimal evaluation value, f j - This is the worst possible rating.

[0035] In conjunction with the first aspect, the preset VIKOR evaluation model is further based on the following form of L p- measure:

[0036] (5)

[0037] In equation (5), f j * For the optimal evaluation value, f j - w represents the worst possible evaluation value. j The weights of each evaluation criterion.

[0038] In conjunction with the first aspect, further, the S-value of the pre-defined VIKOR evaluation model is calculated. i R i and Q i The calculation is performed using the following formula:

[0039] (6)

[0040] (7)

[0041] (8)

[0042] In equation (6), S i For maximum group utility, L 1，i measure;

[0043] In equation (7), R i The regret for the smallest individual is L. ∞，i measure;

[0044] In equation (8), , v is the decision mechanism coefficient, satisfying v∈[0,1]. v>0.5 indicates that the decision is made according to the decision mechanism that maximizes group utility, v<0.5 indicates that the decision is made according to the decision mechanism that minimizes individual regret, and v=0.5 indicates that the decision is made according to the decision mechanism that reaches a consensus through consultation among decision-makers.

[0045] Secondly, the present invention provides a system for determining the optimal power output ratio scheme for wind, solar, and thermal baling, comprising:

[0046] Acquisition module: used to acquire the basic parameters of the wind-thermal bundled DC transmission system under different schemes with wind power output, photovoltaic power output, and thermal power output ratios;

[0047] Calculation module: used to calculate the safety and economic indicators of different proportion schemes based on the acquired basic parameters;

[0048] The sorting module is used to sort the safety and economic indicators of different proportion schemes using the preset VIKOR evaluation model to obtain the optimal scheme.

[0049] Output module: Used to output the optimal output ratio of the wind power, photovoltaic power and thermal power bundled DC transmission system based on the ratio of wind power output, photovoltaic power output and thermal power output in the optimal scheme.

[0050] Thirdly, the present invention provides a computer device, including a processor and a storage medium;

[0051] The storage medium is used to store instructions;

[0052] The processor is configured to operate according to the instructions to perform the steps of the method described in the first aspect.

[0053] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that the program, when executed by a processor, implements the steps of the method described in the first aspect.

[0054] Compared with the prior art, the beneficial effects achieved by the method and system for determining the optimal output ratio of wind, solar and thermal power baling provided in this embodiment of the invention include:

[0055] This invention obtains the basic parameters of a wind-solar-thermal bundled DC transmission system under different ratios of wind, solar, and thermal power outputs. Based on these parameters, it calculates the safety and economic indicators for different ratio schemes. Using a pre-defined VIKOR evaluation model, it ranks the safety and economic indicators of different ratio schemes to obtain the optimal scheme. Based on the ratio of wind, solar, and thermal power outputs in the optimal scheme, it outputs the optimal output ratio of the wind-solar-thermal bundled DC transmission system. This invention proposes safety and economic indicators based on the characteristics of power grid operation, and through the VIKOR evaluation model, it comprehensively evaluates multiple ratio schemes to select the optimal wind-solar-thermal bundled scheme. This is of great significance for guiding the expansion of new energy transmission capacity and ensuring the safety and reliability of the power grid. Attached Figure Description

[0056] Figure 1 This is a flowchart of a method for determining the optimal output ratio scheme of wind, solar and thermal power bundling according to Embodiment 1 of the present invention;

[0057] Figure 2 This is a model diagram of a DC power transmission system for wind-solar-thermal power bundling, which is a method for determining the optimal output ratio scheme of wind-solar-thermal power bundling in Embodiment 1 of the present invention.

[0058] Figure 3 This is a schematic diagram of the system acceleration power after a three-phase short circuit fault occurs in a method for determining the optimal output ratio scheme of wind, solar and thermal power bundling in Embodiment 1 of the present invention.

[0059] Figure 4 This is a voltage change diagram of the sending-end node during a three-phase short-circuit fault in a method for determining the optimal output ratio scheme of wind, solar and thermal power bundling in Embodiment 1 of the present invention.

[0060] Figure 5 This is a graph showing the change in the maximum power angle difference of a thermal power unit experiencing a three-phase short circuit fault in a method for determining the optimal output ratio of wind, solar, and thermal power bundling in Embodiment 1 of the present invention. Detailed Implementation

[0061] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0062] Example 1:

[0063] like Figure 1 As shown, this embodiment of the invention provides a method for determining the optimal power output ratio scheme for wind, solar, and thermal baling, including:

[0064] Obtain the basic parameters of the wind-thermal bundled DC transmission system under different schemes with varying wind power, photovoltaic power, and thermal power output ratios;

[0065] Based on the obtained basic parameters, calculate the safety and economic indicators of different proportion schemes;

[0066] Using the pre-set VIKOR evaluation model, the safety and economic indicators of different proportion schemes are ranked to obtain the optimal scheme.

[0067] Based on the ratio of wind power output, photovoltaic power output, and thermal power output in the optimal scheme, the optimal output ratio of the wind-thermal bundled DC transmission system is output.

[0068] The specific steps include:

[0069] Step 1: Obtain the basic parameters of the wind-thermal bundled DC transmission system under different schemes with varying wind power, photovoltaic power, and thermal power output ratios.

[0070] Step 2: Based on the obtained basic parameters, calculate the safety and economic indicators of different proportion schemes.

[0071] Safety indicators include: system acceleration energy, maximum voltage deviation at critical nodes, and maximum power angle. Economic indicators include the levelized cost of energy (LCOE).

[0072] From the perspective of system energy, the transient power angle stability of a power system essentially reflects whether the unbalanced energy injected during a fault can be absorbed. If the increased kinetic energy of the rotor after the disturbance is not fully absorbed, the generator rotor will continue to accelerate under the influence of the unbalanced power, and the energy will continue to increase, causing system power angle instability. Therefore, the system acceleration energy index after the fault ends is taken as the stability index, expressed by the following formula:

[0073] (1)

[0074] In equation (1), E acc P represents the system's acceleration energy index. m P represents the mechanical power of the generator. e δ represents the generator's electromagnetic power; δ is the generator's power angle.

[0075] Transient voltage stability refers to the voltage stability of each load node in a power system after a large disturbance. The transition of voltage from a controllable state to an uncontrollable state is a key characteristic of deteriorating voltage stability. For the voltage stability index of this system, this invention uses the maximum deviation ΔU of the critical bus voltage from the rated voltage of the bus node in the wind-fire combined system after the fault has occurred. The maximum deviation of the critical node voltage is expressed by the following formula:

[0076] (2)

[0077] In equation (2), ΔU represents the maximum voltage deviation index of the critical node, and U represents the actual voltage value of the bus node; U N This refers to the rated voltage of the busbar node.

[0078] Regarding transient power angle stability, an electromagnetic transient process occurs after a system disturbance, resulting in relative motion between the generator rotors and a change in their relative angle. To assess the system's transient power angle safety level, this invention uses the unit's maximum power angle during the transient process. The maximum power angle index is the maximum value of the thermal power unit's power angle after a fault, relative to a reference value. A larger value indicates poorer transient power angle stability of the system. The maximum power angle index is expressed by the following formula:

[0079] (3)

[0080] In equation (3), δ θ θ represents the maximum power angle index. i θ represents the power angle of a thermal power unit during a transient process. N Indicates the power angle of the reference unit.

[0081] LCOE is a method for comparing the costs of different power generation technologies over their life cycle, and can be used to compare power generation technologies with different cost structures.

[0082] If the value F in each future period is known to be lower than the value P in the present period, this difference is measured by the discount rate r, i.e.:

[0083] (4)

[0084] Net Present Value (NPV) is the collection of values ​​over multiple periods, typically referring to all periods within the lifespan of a project. The definition of LCOE (Lower Cost of Equity) stems from the identity that the net present value of revenue equals the net present value of costs.

[0085] (5)

[0086] Assume P n Since the mean value is constant and does not change with n, the energy cost LCOE index is obtained from the above formula and expressed by the following formula:

[0087] (6)

[0088] In equation (6), P n The LCOE (Levelized Cost of Energy) indicator, C n B represents the total expenditure in year n. n Let A represent income from other sources in year n. n Let r represent the electrical energy produced in year n, and r represent the discount rate.

[0089] Step 3: Using the preset VIKOR evaluation model, rank the safety and economic indicators of different proportion schemes to obtain the optimal scheme.

[0090] Step 3.1: Initialize the different proportion schemes as alternative scheme A i (i=1,2,…,n).

[0091] Step 3.2: Based on the safety and economic indicators of the alternative solutions, the optimal and worst evaluation values ​​of the alternative solutions are calculated using the evaluation criteria of the preset VIKOR evaluation model.

[0092] The pre-defined evaluation criterion for the VIKOR evaluation model is C. j (j=1,2,…,m), then alternative solution A i The evaluation value of (i=1,2,…,n) is f ij ;

[0093] When evaluation criterion C j When using a benefit-based criterion, ,

[0094] When evaluation criterion C j When using a cost-based criterion, ,

[0095] Among them, f j * For the optimal evaluation value, f j - This is the worst possible rating.

[0096] Step 3.3: Based on the calculated optimal and worst evaluation values, calculate the S-value of the pre-set VIKOR evaluation model. i and R i S was obtained from the calculation. i and R i Calculate Q i .

[0097] It should be noted that the preset VIKOR evaluation model is based on the following form of L p- measure:

[0098] (7)

[0099] In equation (7), f j * For the optimal evaluation value, f j - w represents the worst possible evaluation value. j The weights of each evaluation criterion.

[0100] L p- The measure is based on the Lp space, which is a space consisting of p-integrable functions.

[0101] Calculate the S of the pre-defined VIKOR evaluation model i and R i The calculation is performed using the following formula:

[0102] (8)

[0103] (9)

[0104] In equation (8), S i For maximum group utility, L 1，i measure;

[0105] In equation (9), R i The regret for the smallest individual is L. ∞，i measure.

[0106] S is obtained from the calculation. i and R i Calculate Q i The calculation is performed using the following formula:

[0107] (10)

[0108] In equation (10), , v is the decision mechanism coefficient, satisfying v∈[0,1]. v>0.5 indicates that the decision is made according to the decision mechanism that maximizes group utility, v<0.5 indicates that the decision is made according to the decision mechanism that minimizes individual regret, and v=0.5 indicates that the decision is made according to the decision mechanism that reaches a consensus through consultation among decision-makers.

[0109] Step 3.4: According to Q i The values ​​are incremented, and the candidate solutions are sorted to obtain a sequence A of candidate solutions. (1) A (2) A (J) A (n) .

[0110] Step 3.5: Output the first alternative solution A in the sequence. (1) This is the optimal solution.

[0111] Step 4: Based on the ratio of wind power output, photovoltaic power output, and thermal power output in the optimal scheme, output the optimal output ratio of the wind-thermal bundled DC transmission system.

[0112] This invention proposes safety and economic indicators based on the characteristics of power grid operation. By using the VIKOR evaluation model to comprehensively evaluate various ratio schemes, it can select the optimal wind-solar-thermal power bundling scheme. This is of great significance for guiding the expansion of new energy transmission capacity and ensuring the safety and reliability of the power grid.

[0113] Example 2:

[0114] This invention embodiment is a specific application scenario of the method for determining the optimal output ratio scheme of wind, solar and thermal power bundling provided in Embodiment 1.

[0115] Based on the actual distribution of new energy sources in the power system, a model of a bundled AC / DC power transmission system combining wind, solar, and thermal power is established using PSD-BPA simulation software, such as... Figure 2 As shown, wind power, photovoltaic power, and thermal power are collected at the nearest collection station and then transmitted to the receiving end infinite AC system via a double-circuit transmission channel through the sending-end node.

[0116] This invention selects several combinations of wind, solar, and thermal power output ratios for simulation experiments, keeping the total output constant at 1000MW. The several schemes are shown in the table below:

[0117] Table 1. Different scale schemes (unit: MW)

[0118] plan Wind power output Photovoltaic power output Thermal power output Proportion 1 100 100 800 1:1:8 2 200 200 600 2:2:6 3 300 200 500 3:2:5 4 300 300 400 3:3:4 5 400 200 400 4:2:4 6 400 400 200 4:4:2

[0119] A three-phase short-circuit fault is simulated on a single transmission line, occurring in 0.1 seconds and lasting for 0.2 seconds. The simulation duration is 100 cycles. The results obtained using PSD-BPA software are as follows: Figure 3 The accelerating power of the thermal power output shown is as follows: Figure 4 The voltage variation diagram of the sending node is shown below and as follows: Figure 5 The graph shows the variation of the maximum power angle difference of the thermal power unit.

[0120] Calculate the long-term average investment cost for the three power generation methods: wind power (LCOE) is 0.5021 yuan / kWh, photovoltaic power (LCOE) is 0.746 yuan / kWh, and thermal power (LCOE) is 0.356 yuan / kWh. Calculate the safety and economic indicators for different power generation ratios.

[0121] Table 2 Indicator Calculation Results

[0122] Way Target 1 / MW Indicator 2 Indicator 3 / ° Indicator 4 / 10,000 yuan 1 872.5013 97.0381 360.0000 40.9610 2 848.5950 92.4762 360.0000 46.3220 3 698.6123 91.1143 360.0000 56.7830 4 641.2357 95.2190 360.0000 51.6830 5 347.1088 56.7714 140.9719 49.2440 6 339.8484 38.3333 114.1560 57.0440

[0123] Among them, indicator 1 is the system acceleration energy indicator; indicator 2 is the maximum voltage deviation of key nodes indicator; indicator 3 is the maximum power angle indicator; and indicator 4 is the energy cost (LCOE) indicator.

[0124] Using the pre-defined VIKOR evaluation model, the safety and economic indicators of different proportion schemes were ranked to obtain the optimal scheme. The calculation results are shown in Table 3:

[0125] Table 3 Calculation Results

[0126] plan Proportion Q value 1 1:1:8 0.1637 2 2:2:6 0.2802 3 3:2:5 0.9838 4 3:3:4 0.5382 5 4:2:4 0.0150 6 4:4:2 0.6311

[0127] As can be seen from Table X, Scheme 5 has the lowest Q value, making it the optimal choice among all schemes. The optimal output ratio of the wind-thermal bundled DC transmission system should be the ratio of wind power output, photovoltaic output, and thermal power output corresponding to Scheme 5, i.e., 400MW wind power output, 200MW photovoltaic output, and 400MW thermal power output, with a ratio of 4:2:4.

[0128] Example 3:

[0129] This invention provides a system for determining the optimal power output ratio scheme for wind, solar, and thermal power bundling, comprising:

[0130] Acquisition module: used to acquire the basic parameters of the wind-thermal bundled DC transmission system under different schemes with wind power output, photovoltaic power output, and thermal power output ratios;

[0131] Calculation module: used to calculate the safety and economic indicators of different proportion schemes based on the acquired basic parameters;

[0132] The sorting module is used to sort the safety and economic indicators of different proportion schemes using the preset VIKOR evaluation model to obtain the optimal scheme.

[0133] Output module: Used to output the optimal output ratio of the wind power, photovoltaic power and thermal power bundled DC transmission system based on the ratio of wind power output, photovoltaic power output and thermal power output in the optimal scheme.

[0134] Example 4:

[0135] This invention provides a computer device, including a processor and a storage medium;

[0136] The storage medium is used to store instructions;

[0137] The processor is configured to operate according to the instructions to execute the steps of the method described in Embodiment 1.

[0138] Example 5:

[0139] The present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that the program, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0140] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0141] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0142] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0143] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0144] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the optimal power output ratio scheme for wind, solar, and thermal power bundling, characterized in that, include: Obtain the basic parameters of the wind-thermal bundled DC transmission system under different schemes with varying wind power, photovoltaic power, and thermal power output ratios; Based on the obtained basic parameters, calculate the safety and economic indicators of different proportion schemes; The safety indicators include: system acceleration energy index, maximum voltage deviation of key nodes index, and maximum power angle index; From the perspective of system energy, the transient power angle stability of a power system essentially reflects whether the unbalanced energy injected during a fault can be absorbed. If the increased kinetic energy of the rotor after the disturbance is not fully absorbed, the generator rotor will continue to accelerate under the influence of the unbalanced power, and the energy will continue to increase, causing the system power angle to become unstable. The system acceleration energy index after the fault ends is taken as the stability index, expressed by the following formula: （1） In equation (1), E acc P represents the system's acceleration energy index. m P represents the mechanical power of the generator. e This represents the electromagnetic power of the generator; δ is the generator power angle. Transient voltage stability refers to the voltage stability of each load node in a power system after being subjected to a large disturbance. The transition of voltage from a controllable state to an uncontrollable state is a key characteristic of deteriorating voltage stability. For the voltage stability of a combined wind and fire system, the maximum deviation of the critical bus voltage from the rated voltage of the bus node after the fault has occurred is used as the indicator. The maximum deviation of the critical node voltage is expressed by the following formula: （2） In equation (2), ΔU represents the maximum voltage deviation index of the critical node, and U represents the actual voltage value of the bus node; U N The rated voltage of the busbar node; Regarding the transient power angle stability problem, an electromagnetic transient process occurs after system disturbance, resulting in relative motion between generator rotors and changes in their relative angle. The maximum power angle of the unit during the transient process is used to assess the system's transient power angle safety level. The maximum power angle index is the maximum value of the thermal power unit's power angle after a fault relative to a reference value. A larger maximum power angle index indicates poorer transient power angle stability of the combined wind and thermal power system. The maximum power angle index is expressed by the following formula: （3） In equation (3), δ θ θ represents the maximum power angle index. i θ represents the power angle of a thermal power unit during a transient process. N Indicates the power angle of the reference unit; The economic indicators mentioned above include the energy cost LCOE indicator; If the value F in each future period is known to be lower than the value P in the present period, this difference is measured by the discount rate r, i.e.: （4） Net Present Value (NPV) is the collection of values ​​over multiple periods, typically referring to all periods within the lifespan of a project. The definition of LCOE (Lower Cost of Equity) comes from the identity that the net present value of revenue equals the net present value of costs, i.e.: （5） Assume P n Since the mean value is constant and does not change with n, the energy cost LCOE index is obtained from the above formula and expressed by the following formula: （6） In equation (6), P n The LCOE (Levelized Cost of Energy) indicator, C n B represents the total expenditure in year n. n Let A represent income from other sources in year n. n Let r represent the electrical energy produced in year n, and r represent the discount rate. Using the pre-set VIKOR evaluation model, the safety and economic indicators of different proportion schemes are ranked to obtain the optimal scheme. Based on the ratio of wind power output, photovoltaic power output, and thermal power output in the optimal scheme, the optimal output ratio of the wind-thermal bundled DC transmission system is output.

2. The method for determining the optimal output ratio scheme of wind, solar, and thermal power bundling according to claim 1, characterized in that, The process of obtaining the optimal solution includes: Initialize each different ratio scheme as alternative scheme A i (i=1,2,…,n); Based on the safety and economic indicators of the alternative solutions, the optimal and worst evaluation values ​​of the alternative solutions are calculated using the evaluation criteria of the preset VIKOR evaluation model. Based on the calculated optimal and worst evaluation values, the S-value of the pre-defined VIKOR evaluation model is calculated. i and R i S was obtained from the calculation. i and R i Calculate Q i ; According to Q i The values ​​are incremented, and the candidate solutions are sorted to obtain a sequence of candidate solutions; The first option in the output sequence is the optimal solution.

3. The method for determining the optimal output ratio scheme of wind, solar, and fire baling according to claim 2, characterized in that, The calculation of the optimal and worst evaluation values ​​of the alternative solutions includes: The evaluation criterion of the preset VIKOR evaluation model is C. j (j=1,2,…,m), then alternative solution A i The evaluation value of (i=1,2,…,n) is f ij ; When evaluation criterion C j When using a benefit-based criterion, , When evaluation criterion C j When using a cost-based criterion, , Among them, f j * For the optimal evaluation value, f j - This is the worst possible rating.

4. The method for determining the optimal output ratio scheme of wind-solar-fired power baling according to claim 3, characterized in that, The preset VIKOR evaluation model is based on the following form of L p- measure: （7） In equation (7), f j * For the optimal evaluation value, f j - w represents the worst possible evaluation value. j The weights of each evaluation criterion.

5. The method for determining the optimal output ratio scheme of wind, solar, and thermal power bundling according to claim 4, characterized in that, Calculate the S of the pre-defined VIKOR evaluation model i R i and Q i The calculation is performed using the following formula: （8） （9） （10） In equation (8), S i For maximum group utility, L is 1，i measure; In equation (9), R i The regret for the smallest individual is L. ∞，i measure; In equation (10), , v is the decision mechanism coefficient, satisfying v∈[0,1]. v>0.5 indicates that the decision is made according to the decision mechanism that maximizes group utility, v<0.5 indicates that the decision is made according to the decision mechanism that minimizes individual regret, and v=0.5 indicates that the decision is made according to the decision mechanism that reaches a consensus through consultation among decision-makers.

6. A system for determining the optimal power output ratio scheme for wind, solar, and thermal power bundling, characterized in that, include: Acquisition module: used to acquire the basic parameters of the wind-thermal bundled DC transmission system under different schemes with wind power output, photovoltaic power output, and thermal power output ratios; Calculation module: used to calculate the safety and economic indicators of different proportion schemes based on the acquired basic parameters; The safety indicators include: system acceleration energy index, maximum voltage deviation of key nodes index, and maximum power angle index; From the perspective of system energy, the transient power angle stability of a power system essentially reflects whether the unbalanced energy injected during a fault can be absorbed. If the increased kinetic energy of the rotor after the disturbance is not fully absorbed, the generator rotor will continue to accelerate under the influence of the unbalanced power, and the energy will continue to increase, causing the system power angle to become unstable. The system acceleration energy index after the fault ends is taken as the stability index, expressed by the following formula: （1） In equation (1), E acc P represents the system's acceleration energy index. m P represents the mechanical power of the generator. e This represents the electromagnetic power of the generator; δ is the generator power angle. Transient voltage stability refers to the voltage stability of each load node in a power system after being subjected to a large disturbance. The transition of voltage from a controllable state to an uncontrollable state is a key characteristic of deteriorating voltage stability. For the voltage stability of a combined wind and fire system, the maximum deviation of the critical bus voltage from the rated voltage of the bus node after the fault has occurred is used as the indicator. The maximum deviation of the critical node voltage is expressed by the following formula: （2） In equation (2), ΔU represents the maximum voltage deviation index of the critical node, and U represents the actual voltage value of the bus node; U N The rated voltage of the busbar node; Regarding the transient power angle stability problem, an electromagnetic transient process occurs after system disturbance, resulting in relative motion between generator rotors and changes in their relative angle. The maximum power angle of the unit during the transient process is used to assess the system's transient power angle safety level. The maximum power angle index is the maximum value of the thermal power unit's power angle after a fault relative to a reference value. A larger maximum power angle index indicates poorer transient power angle stability of the combined wind and thermal power system. The maximum power angle index is expressed by the following formula: （3） In equation (3), δ θ θ represents the maximum power angle index. i θ represents the power angle of a thermal power unit during a transient process. N Indicates the power angle of the reference unit; The economic indicators mentioned above include the energy cost LCOE indicator; If the value F in each future period is known to be lower than the value P in the present period, this difference is measured by the discount rate r, i.e.: （4） Net Present Value (NPV) is the collection of values ​​over multiple periods, typically referring to all periods within the lifespan of a project. The definition of LCOE (Lower Cost of Equity) comes from the identity that the net present value of revenue equals the net present value of costs, i.e.: （5） Assume P n Since the mean value is constant and does not change with n, the energy cost LCOE index is obtained from the above formula and expressed by the following formula: （6） In equation (6), P n The LCOE (Levelized Cost of Energy) indicator, C n B represents the total expenditure in year n. n Let A represent income from other sources in year n. n Let r represent the electrical energy produced in year n, and r represent the discount rate. The sorting module is used to sort the safety and economic indicators of different proportion schemes using the preset VIKOR evaluation model to obtain the optimal scheme. Output module: Used to output the optimal output ratio of the wind power, photovoltaic power and thermal power bundled DC transmission system based on the ratio of wind power output, photovoltaic power output and thermal power output in the optimal scheme.

7. A computer device, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1 to 5.

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