Long-period power grid wind-solar-thermal storage operation scheduling optimization method

Abstract

The invention relates to the technical field of new energy power transmission, and discloses a long-period power grid wind-solar-thermal storage operation scheduling optimization method, which comprises the following steps: S1, constructing a new energy base system model, and calculating an output curve; s2, constructing an extra-high voltage direct current channel power delivery model; s3, solving the extra-high-voltage direct-current channel power delivery model by using CPLEX to obtain a direct-current channel delivery power optimization curve taking maximization of a new energy consumption rate considering the proportion of wind power and photovoltaic power at a delivery end as a target; s4, constructing a receiving end power grid system model; and the optimal matched power supply scale taking the minimum power abandoning rate of the new energy at the receiving end as a target function is obtained by the CPLEX. The method has the advantages that the direct-following-source-moving sending-out mode aims at meeting the external sending power requirement of a matched new energy base, the planning cost is effectively reduced, and the direct-current sending-out power and wind-light-storage power generation are coordinated and consistent.

Description

Technical Field

[0001] The present invention relates to the field of renewable energy power transmission technology, and in particular to a method for optimizing wind, solar, thermal and energy storage operation dispatching in a long-period power grid. Background Art

[0002] my country has gradually adopted "electric energy substitution" and "clean energy substitution" as the main energy consumption methods. By the end of 2022, my country's new energy installed capacity has reached 760 million kilowatts, making my country the country with the largest new energy installed capacity in the world. With the continuous growth of energy development demand, the status and role of clean energy will be further enhanced, and China's new energy development will also maintain a high-speed growth trend.

[0003] In recent years, deserts, Gobi and wasteland areas have great potential for the development of new energy due to their wind and solar energy resources, which provides important opportunities for the development of large-scale new energy bases in deserts, Gobi and wasteland areas and the large-scale transmission of AC / DC hybrid power grids.

[0004] The UHV DC system is an important tool for dealing with high voltage, large capacity and long-distance power transmission, and is also the key to grid interconnection. Considering that the energy and load in the "Shagohuang" area are distributed inversely, the use of the UHV DC system can effectively and reliably transmit the local centralized grid-connected wind and solar power generation to the load center, thereby realizing the cross-regional optimization and efficient consumption of wind and solar resources in the "Shagohuang" area. In recent years, the following research has been conducted on the UHV cross-regional DC transmission system for new energy bases: the existing technology of UHV DC wind power and thermal power combined transmission power scale optimization method and UHV DC transmission wind, solar and thermal power integrated dispatching plan model proposed a method for optimizing the combined transmission of wind power and thermal power in the UHV DC system, which expands the consumption range of wind power by adjusting the scale of supporting power sources and improves the transmission efficiency of the UHV DC channel. The existing technology of the combined transmission optimization configuration of large-scale wind, solar and thermal energy bases uses the complementarity rate as an evaluation index to determine the optimal wind and solar installed capacity ratio, and then through the combined transmission of large-scale wind, solar and thermal energy bases, the complementary benefits of wind power generation and photovoltaic power generation in time and space are realized, and the channel utilization rate of the transmission project is improved, so as to achieve the goal of maximizing the overall economic benefits. The existing technology of the distributed dispatch approach for bulk AC / DC hybrid systems with high windpower penetration aims to solve the problem of insufficient power grading control accuracy, and proposes a power generation plan optimization model that describes the power operation of DC interconnection lines in grades. The existing technology of the optimization model of a combined wind-PV-thermal dispatching system under carbon emissions trading in China has established a wind-solar-thermal combined transmission dispatch optimization model under the carbon emissions trading mechanism to reasonably configure new energy such as wind power, photovoltaics and thermal power units. The existing technology of the multi-objective optimization of the wind-solar-thermal combined transmission dispatch strategy considering economic-environmental balance is based on the principle of economic-environmental balance, and on the basis of minimizing the fluctuation of new energy output and taking the enterprise's electricity purchase cost as the goal, an optimization model for solving multi-objective priorities for the combined dispatch of wind, solar and thermal power is established. The existing technology considers the frequency security constraints of the Northwest Power Grid's new energy development and DC transmission scale assessment method. Based on production simulation, a simulation algorithm in the frequency security time domain is developed to accurately calculate the scale of new energy development and DC transmission. The existing technology improves the penetration rate of new energy. The wind-solar-thermal combined DC transmission method proposes a day-ahead economic dispatch strategy to improve the absorption capacity of new energy by optimizing the proportion of thermal power output in the transmitted power.The existing technology of large-scale new energy bases has created an aggregated operation model of various types of power stations through the optimization method of the medium- and long-term operation mode of the UHV DC transmission system. On this basis, a UHV DC operation model is designed. The model does not contain any integer variables, thereby realizing the maximum transmission and consumption of new energy. The existing technology supports the power supply combination optimization configuration strategy of new energy base power transmission. The power supply expansion optimization model is constructed by the time series production simulation method, and the optimization combination strategy of regulating power supply and new energy installed capacity under different power transmission schemes is studied. It is proposed to adjust the joint development and configuration of multiple new energy bases according to seasonal regulation.

[0005] Given the uncertainty of new energy output, the DC transmission from new energy bases in desert Gobi desert areas is characterized by randomness, volatility and intermittency, which is significantly different from the traditional DC system. Therefore, the key to the transmission of new energy is to effectively meet the predetermined transmission plan, which usually requires the operation plan of the transmission power and the interconnection line to be determined in advance, which is obviously planned. At present, the research on UHV DC transmission in my country is mainly focused on optimizing the operation mode in terms of improving the operating stability of DC transmission channels and improving the peak-shaving margin of the receiving power grid. However, there is still room for further exploration in terms of reasonably selecting the ratio of thermal power capacity, increasing the proportion of new energy in the transmission power, fully transmitting and utilizing the power at the sending end, and considering the dynamic adjustment capability of the receiving power grid. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a long-term power grid wind, solar, thermal and storage operation scheduling optimization method.

[0007] The purpose of the present invention is achieved through the following technical solution: A long-period power grid wind, solar, thermal and storage operation scheduling optimization method comprises the following steps:

[0008] Step S1: Collect typical 8760 hourly output characteristics and load data of conventional units, wind power and photovoltaic power in a certain power grid, build a new energy base system model based on the collected data, and then calculate the output curve based on the new energy base system model;

[0009] Step S2: Based on the regulation requirements of wind power, photovoltaic power, energy storage and thermal power in the new energy base at the sending end, a UHV DC channel power transmission model is constructed;

[0010] Step S3: Using CPLEX to solve the UHV DC channel power transmission model, an optimization curve for DC channel transmission power is obtained with the goal of maximizing the new energy consumption rate taking into account the proportion of wind power and photovoltaic power at the transmission end;

[0011] Step S4: Construct a receiving-end power grid system model; use the UHV DC channel transmission power obtained by the sending-end optimization as the receiving-end input; and use CPLEX to determine the optimal supporting power supply scale with the minimum power abandonment rate of new energy at the receiving end as the objective function.

[0012] Specifically, the new energy base system model includes a new energy unit output model, a thermal power unit output model and an energy storage operation model.

[0013] Specifically, the new energy unit output model includes:

[0014] Wind turbine output model:

[0015]

[0016] Where P wind It represents the actual power consumption of wind turbine in period t; Indicates the absorbable output of the wind turbine;

[0017] Photovoltaic unit output model:

[0018]

[0019] Where P pv It represents the actual power consumption of the photovoltaic unit in the period t; Indicates the absorbable output of the photovoltaic unit.

[0020] Specifically, the output model of the thermal power unit is:

[0021]

[0022] In the formula, R thermal It is a 0-1 variable, indicating the operating status of the thermal power unit in period t, which is 1 when it is running and 0 when it is stopped; Respectively represent the upper and lower limits of the output of thermal power units; P thermal It represents the actual output of thermal power unit in period t;

[0023] Specifically, the constraints of the thermal power unit output model include:

[0024] Thermal power unit climbing constraints:

[0025]

[0026] In the formula, SU thermal , SD thermal Both are 0-1 variables, representing the startup state variables and shutdown variables of the thermal power unit in the t period. The value becomes 1 at the moment when the thermal power unit starts or stops, and the value is 0 at other times; UR thermal ,DRthermal They represent the maximum up and down ramp rates of thermal power units respectively; NT represents the dispatching period;

[0027] Constraints on the operating status of thermal power units:

[0028]

[0029] Start and stop time constraints of thermal power units:

[0030]

[0031] Where, T on 、T off Respectively represent the minimum start and stop time of thermal power units; UT thermal , DT thermal The initial time of thermal power units is

[0032] The time when the machine must be started or stopped; τ is the sequence number of the current time period;

[0033] If the initial time is in the running state, when the initial startup time is less than the minimum startup time:

[0034]

[0035] Where U init (0) is the time when the thermal power unit has been started at the initial moment;

[0036] If the initial moment is the shutdown state, when the initial shutdown time is less than the minimum shutdown time:

[0037]

[0038] Where D init (0) is the time when the thermal power unit has been shut down at the initial moment.

[0039] Specifically, the energy storage operation model includes:

[0040] Energy storage rated power constraints:

[0041]

[0042] Where P ch , P dis They represent the actual charging and discharging power of the energy storage in period t respectively; Indicates the upper limit of the charging and discharging power of energy storage; s ch 、s dis are all 0-1 variables, indicating the charging and discharging state of the energy storage in time period t. When the energy storage is in the charging state, s ch The value is 1, s dis The value is 0; on the contrary, when the energy storage is in the discharge state, sch The value is 0, s dis The value is 1;

[0043] Energy storage state of charge constraints:

[0044]

[0045] E storage (0) = E0

[0046] E storage (NT) = E NT

[0047] In the formula, They represent the upper and lower limits of the energy storage capacity, respectively. The continuous charging and discharging time of the energy storage is 2 hours; E storage represents the energy storage capacity in time period t; η represents the energy storage charging and discharging efficiency; E0 represents the energy storage capacity at the initial moment of the scheduling cycle, E NT It represents the energy storage capacity at the end of the dispatch period, usually the two are equal; NT represents the dispatch period;

[0048] Energy storage charging and discharging state constraints:

[0049]

[0050] Specifically, the objective function of the UHV DC channel power transmission model is:

[0051]

[0052] The constraints of the UHV DC channel power transmission model include:

[0053] DC power transmission range constraints:

[0054]

[0055] In the formula, Indicates the upper limit of the DC transmission capacity of the DC channel; P DC Indicates the actual external power of the DC channel in period t; DC constant power operation time constraint:

[0056]

[0057] Where, τ represents the minimum DC constant operating time; v DC is a 0-1 variable, indicating whether the transmitted DC power is adjusted during the t period. When the DC power changes, v DC The value is 1, otherwise it is 0;

[0058] Transmission power switching constraints:

[0059]

[0060] DC line ramp power constraints in adjacent time periods:

[0061]

[0062] In the formula, UR DC ,DR DC They represent the maximum up and down ramp rates of the UHV DC transmission channel respectively;

[0063] Constraints on average utilization hours of DC channels:

[0064]

[0065] Specifically, the objective function of the receiving-end power grid system model is:

[0066]

[0067] Among them, CWR is the wind power abandonment rate, and CSR is the photovoltaic power abandonment rate;

[0068] The constraints of the receiving-end power grid system model are:

[0069] Power balance constraints:

[0070]

[0071] The present invention has the following advantages:

[0072] The proposed UHV DC model takes into account the operating requirements of DC, the maximum supply capacity of the sending power grid and the load peak regulation demand of the receiving power grid. It adopts a direct-follow-source transmission mode to meet the external power transmission demand of the supporting new energy base and effectively reduce the planning cost, so that the DC transmission power is coordinated with wind-solar-storage power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 It is a schematic diagram of the flow chart of the wind, solar, thermal and storage capacity joint operation planning optimization method of the present invention;

[0074] Figure 2 It is the actual output diagram of thermal power in the base;

[0075] Figure 3 This is the actual photovoltaic output diagram of the base;

[0076] Figure 4 It is the actual output diagram of wind power in the base;

[0077] Figure 5 It is the actual output diagram of base energy storage;

[0078] Figure 6It is the power output and DC channel transmission curve of the new energy base;

[0079] Figure 7 This is a schematic diagram of the DC transmission new energy power grid in the Shagohuang area. DETAILED DESCRIPTION

[0080] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0081] 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 invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0082] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0083] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description. Figures 1 to 7 As shown, a long-period power grid wind, solar, thermal and storage operation dispatch optimization method includes the following steps:

[0084] Step S1: Collect typical 8760 hourly output characteristics and load data of conventional units, wind power and photovoltaic power in a certain power grid, build a new energy base system model based on the collected data, and then calculate the output curve based on the new energy base system model;

[0085] Step S2: Based on the regulation requirements of wind power, photovoltaic power, energy storage and thermal power in the new energy base at the sending end, a UHV DC channel power transmission model is constructed;

[0086] Step S3: Using CPLEX to solve the UHV DC channel power transmission model, an optimization curve for DC channel transmission power is obtained with the goal of maximizing the new energy consumption rate taking into account the proportion of wind power and photovoltaic power at the transmission end;

[0087] Step S4: Construct a receiving-end power grid system model; use the UHV DC channel transmission power obtained by the sending-end optimization as the receiving-end input; and use CPLEX to determine the optimal supporting power supply scale with the minimum power abandonment rate of new energy at the receiving end as the objective function.

[0088] Furthermore, the new energy base system model includes a new energy unit output model, a thermal power unit output model and an energy storage operation model.

[0089] Furthermore, the output model of the new energy unit includes:

[0090] Wind turbine output model:

[0091]

[0092] Where P wind It represents the actual power consumption of wind turbine in period t; Indicates the absorbable output of the wind turbine;

[0093] Photovoltaic unit output model:

[0094]

[0095] Where P pv It represents the actual power consumption of the photovoltaic unit in the period t; Indicates the absorbable output of the photovoltaic unit.

[0096] Furthermore, the output model of the thermal power unit is:

[0097]

[0098] In the formula, R thermal It is a 0-1 variable, indicating the operating status of the thermal power unit in period t, which is 1 when it is running and 0 when it is stopped; Respectively represent the upper and lower limits of the output of thermal power units; P thermal It represents the actual output of thermal power unit in period t;

[0099] Furthermore, the constraints of the thermal power unit output model include:

[0100] Thermal power unit climbing constraints:

[0101]

[0102]

[0103] In the formula, SU thermal , SD thermal Both are 0-1 variables, representing the startup state variables and shutdown variables of the thermal power unit in the t period. The value becomes 1 at the moment when the thermal power unit starts or stops, and the value is 0 at other times; UR thermal ,DR thermal They represent the maximum up and down ramp rates of thermal power units respectively; NT represents the dispatching period;

[0104] Constraints on the operating status of thermal power units:

[0105]

[0106] Start and stop time constraints of thermal power units:

[0107]

[0108] Where, T on 、T off Respectively represent the minimum start and stop time of thermal power units; UT thermal , DT thermal The initial time of thermal power units is

[0109] The time when the machine must be started or stopped; τ is the sequence number of the current time period;

[0110] If the initial time is in the running state, when the initial startup time is less than the minimum startup time:

[0111]

[0112] Where U init (0) is the time when the thermal power unit has been started at the initial moment;

[0113] If the initial moment is the shutdown state, when the initial shutdown time is less than the minimum shutdown time:

[0114]

[0115] Where D init (0) is the time when the thermal power unit has been shut down at the initial moment.

[0116] Furthermore, the energy storage operation model includes:

[0117] Energy storage rated power constraints:

[0118]

[0119] Where P ch, P dis They represent the actual charging and discharging power of the energy storage in period t respectively; Indicates the upper limit of the charging and discharging power of energy storage; s ch 、s dis are all 0-1 variables, indicating the charging and discharging state of the energy storage in time period t. When the energy storage is in the charging state, s ch The value is 1, s dis The value is 0; on the contrary, when the energy storage is in the discharge state, s ch The value is 0, s dis The value is 1;

[0120] Energy storage state of charge constraints:

[0121]

[0122] E storage (0) = E0

[0123] E storage (NT) = E NT

[0124] In the formula, They represent the upper and lower limits of the energy storage capacity, respectively. The continuous charging and discharging time of the energy storage is 2 hours; E storage represents the energy storage capacity in time period t; η represents the energy storage charging and discharging efficiency; E0 represents the energy storage capacity at the initial moment of the scheduling cycle, E NT It represents the energy storage capacity at the end of the dispatch period, usually the two are equal; NT represents the dispatch period;

[0125] Energy storage charging and discharging state constraints:

[0126]

[0127] Furthermore, in the transmission project of new energy transmission through UHV DC channels, the receiving power grid is usually mainly supplied by thermal power without large-scale new energy units. At present, my country's thermal power configuration is gradually reduced, and the clean energy transmitted by UHV DC channels is used to supply the load. The limited thermal power resources are used to fill the remaining load gap and are no longer the main power generation component. Therefore, the planned power of DC transmission should be as close as possible to the load curve to meet the peak load demand of the receiving power grid. For the formulation of new energy transmission plans in typical scenarios, the core issue is how to make the transmission plan meet the load demand of the receiving power grid to the greatest extent under the premise of meeting the DC transmission operation mode.

[0128] The current UHV DC operation model mainly considers the constraints of the stepped operation of UHV DC transmission power, the transmission range, the power change rate, etc., but does not consider the utilization rate of new energy sources in the sending-end power grid and the load peak regulation demand of the receiving-end power grid. The UHV DC model proposed in the present invention simultaneously considers the operation requirements of DC, the maximum supply capacity of the sending-end power grid and the load peak regulation demand of the receiving-end power grid. The direct-following source-driven transmission mode is used to meet the external transmission power demand of the supporting new energy base, and effectively reduce the planning cost, so that the DC transmission power is coordinated with the wind-light-storage power generation. Since the new energy base includes two output modes, wind power and photovoltaic power, a weight of 50% is given to each of them. The objective function of the UHV DC channel power transmission model is:

[0129]

[0130] The constraints of the UHV DC channel power transmission model include:

[0131] DC power transmission range constraints:

[0132]

[0133] In the formula, Indicates the upper limit of the DC transmission capacity of the DC channel; P DC Indicates the actual external power of the DC channel in period t; DC constant power operation time constraint:

[0134]

[0135] Where, τ represents the minimum DC constant operating time; v DC is a 0-1 variable, indicating whether the transmitted DC power is adjusted during the t period. When the DC power changes, v DC The value is 1, otherwise it is 0;

[0136] Transmission power switching constraints: To ensure the safe and stable operation of the DC channel, the channel transmission power is required to be switched at most twice a day:

[0137]

[0138] DC line ramp power constraints in adjacent time periods:

[0139]

[0140] In the formula, UR DC ,DR DC They represent the maximum up and down ramp rates of the UHV DC transmission channel respectively;

[0141] Constraints on average utilization hours of DC channels: In order to further increase the amount of renewable energy electricity transmitted by UHV DC transmission projects, the utilization hours of UHV DC transmission projects should be maximized, and the following constraints are made:

[0142]

[0143] Furthermore, the optimized P is obtained by using the sending end constraint. DC As the input of the receiving power grid, the receiving power grid power balance and unit output constraints must be met at the same time. The receiving power grid optimization process takes the minimum power abandonment rate of the receiving new energy as the objective function. The objective function of the receiving power grid system model is:

[0144]

[0145] Among them, CWR is the wind power abandonment rate, and CSR is the photovoltaic power abandonment rate;

[0146] The constraints of the receiving-end power grid system model are:

[0147] Power balance constraints

[0148]

[0149] The present invention sets up a simulation example based on the planning scheme of a large-scale new energy base in Northwest my country. In the example, the ultra-high voltage direct current capacity of the large-scale new energy base is 8000MW, and the annual utilization hours are 5356. The total installed capacity of the new energy base is 17000MW, including 4000MW of wind power, 7000MW of photovoltaic power, 4000MW of thermal power and 2000MW / (4000MWh) of electrochemical energy storage. The total installed capacity of new energy accounts for 64.7%. The annual utilization hours of wind power and photovoltaic power are 2637 and 1838 respectively. The minimum technical output of thermal power is 0.3pu. The wind energy absorption rate at the sending end is 97.16%, the photovoltaic absorption rate at the sending end is 89.87%, and the abandoned light rate at the receiving end is 0.29%. The output curve of the new energy base is as follows: Figure 7 .

[0150] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above-mentioned technical content without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any changes, modifications, equivalent changes and modifications made to the above embodiments based on the technology of the present invention without departing from the content of the technical solution of the present invention belong to the protection scope of the present technical solution.

Claims

1. A method for optimizing the operation and dispatching of wind, solar, thermal and storage power grids over a long period, characterized by: The following steps are involved: Step S1: Collect typical 8760 hourly output characteristics and load data of conventional units, wind power and photovoltaic power in a certain power grid, build a new energy base system model based on the collected data, and then calculate the output curve based on the new energy base system model; Step S2: Based on the regulation requirements of wind power, photovoltaic power, energy storage and thermal power in the new energy base at the sending end, a UHV DC channel power transmission model is constructed; Step S3: Using CPLEX to solve the UHV DC channel power transmission model, an optimization curve for DC channel transmission power is obtained with the goal of maximizing the new energy consumption rate taking into account the proportion of wind power and photovoltaic power at the transmission end; Step S4: Construct a receiving-end power grid system model; use the UHV DC channel transmission power obtained by the sending-end optimization as the receiving-end input; and use CPLEX to determine the optimal supporting power supply scale with the minimum power abandonment rate of new energy at the receiving end as the objective function.

2. A long-period power grid wind, solar, thermal and storage operation dispatch optimization method according to claim 1, characterized in that: The new energy base system model includes a new energy unit output model, a thermal power unit output model and an energy storage operation model.

3. A long-period power grid wind, solar, thermal and storage operation dispatch optimization method according to claim 2, characterized in that: The output model of the new energy unit includes: Wind turbine output model: Where P wind It represents the actual power consumption of wind turbine in period t; Indicates the absorbable output of the wind turbine; Photovoltaic unit output model: Where P pv It represents the actual power consumption of the photovoltaic unit in the period t; Indicates the absorbable output of the photovoltaic unit.

4. A long-period power grid wind, solar, thermal and storage operation dispatch optimization method according to claim 2, characterized in that: The output model of the thermal power unit is: In the formula, R thermal It is a 0-1 variable, indicating the operating status of the thermal power unit in period t, which is 1 when it is running and 0 when it is stopped; Respectively represent the upper and lower limits of the output of thermal power units; P thermal Represents the actual output of the thermal power unit during period t.

5. A long-period power grid wind, solar, thermal and storage operation dispatch optimization method according to claim 4, characterized in that: The constraints of the thermal power unit output model include: Thermal power unit climbing constraints: In the formula, SU thermal , SD thermal Both are 0-1 variables, representing the startup state variables and shutdown variables of the thermal power unit in the t period. The value becomes 1 at the moment when the thermal power unit starts or stops, and the value is 0 at other times; UR thermal ,DR thermal They represent the maximum up and down ramp rates of thermal power units respectively; NT represents the dispatching period; Constraints on the operating status of thermal power units: Start and stop time constraints of thermal power units: Where, T on , T off Respectively represent the minimum start and stop time of thermal power units; UT thermal , DT thermal The initial time of thermal power units is The time when the machine must be started or stopped; τ is the sequence number of the current time period; If the initial time is in the running state, when the initial startup time is less than the minimum startup time: Where U init (0) is the time when the thermal power unit has been started at the initial moment; If the initial moment is the shutdown state, when the initial shutdown time is less than the minimum shutdown time: Where D init (0) is the time when the thermal power unit has been shut down at the initial moment.

6. A long-period power grid wind, solar, thermal and storage operation dispatch optimization method according to claim 2, characterized in that: The energy storage operation model includes: Energy storage rated power constraints: Where P ch , P dis They represent the actual charging and discharging power of the energy storage in period t respectively; Indicates the upper limit of the charging and discharging power of energy storage; s ch 、s dis are all 0-1 variables, indicating the charging and discharging state of the energy storage in time period t. When the energy storage is in the charging state, s ch The value is 1, s dis The value is 0; on the contrary, when the energy storage is in the discharge state, s ch The value is 0, s dis The value is 1; Energy storage state of charge constraints: E storage (0)=E0 AND storage (NT)=And NT In the formula, They represent the upper and lower limits of the energy storage capacity, respectively. The continuous charging and discharging time of the energy storage is 2 hours; E storage represents the energy storage capacity in time period t; η represents the energy storage charging and discharging efficiency; E0 represents the energy storage capacity at the initial moment of the scheduling cycle, E NT It represents the energy storage capacity at the end of the dispatch period, usually the two are equal; NT represents the dispatch period; Energy storage charging and discharging state constraints:

7. The method for optimizing the operation and dispatching of wind, solar, thermal and energy storage power grids over a long period according to claim 3 is characterized by: The objective function of the UHV DC channel power transmission model is: The constraints of the UHV DC channel power transmission model include: DC power transmission range constraints: In the formula, Indicates the upper limit of the DC transmission capacity of the DC channel; P DC It represents the actual external power of the DC channel in period t; DC constant power operation time constraints: Where, τ represents the minimum DC constant operating time; v DC is a 0-1 variable, indicating whether the transmitted DC power is adjusted during the t period. When the DC power changes, v DC The value is 1, otherwise it is 0; Transmission power switching constraints: DC line ramp power constraints in adjacent time periods: In the formula, UR DC ,DR DC They represent the maximum up and down ramp rates of the UHV DC transmission channel respectively; Constraints on average utilization hours of DC channels:

8. The method for optimizing the operation and dispatching of wind, solar, thermal and energy storage power grids over a long period according to claim 3 is characterized by: The objective function of the receiving-end power grid system model is: CWR is the wind power curtailment rate, and CSR is the photovoltaic power curtailment rate; The constraints of the receiving-end power grid system model are: Power balance constraints

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