Energy capacity optimization method for direct-current delivery system in intra-region alternating-current and direct-current hybrid scene
By establishing the overall structure and power balance mode of multiple types of clean energy power generation systems, and optimizing the capacity configuration of wind and photovoltaic power stations, the energy types and complementarity of multiple types of clean energy power generation systems in DC export systems in the region are solved. The problem of insufficient sexuality has achieved effective matching between clean energy systems and power grid loads and improved absorption capacity.
Patent Information
- Application Number
- CN202411522102.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-29
- Publication Date
- 2025-02-07
AI Technical Summary
In the mixed AC-DC scenario in the region, there are fewer energy types in the DC transmission system, and there are a lack of in-depth research, making it difficult to achieve effective complementarity and absorption between multiple clean energy types.
By establishing the overall structure and power balance working mode of multi-type clean energy power generation systems, establishing output models, and linearizing nonlinear constraints, establishing a hybrid integer linear model to optimize the capacity configuration of wind and photovoltaic power stations.
The rationality of the wind and light storage capacity configuration in the matching of the clean energy system and the power grid load is achieved, the absorption capacity of multiple types of clean energy is improved, and the wind and light abandonment rate is reduced.
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Figure CN119401582A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of renewable energy power generation, and in particular relates to a method for optimizing the energy capacity of a direct current (DC) transmission system in an intra-regional AC / DC hybrid scenario. Background Art
[0002] At present, efforts are being made to build a clean, low-carbon, safe and efficient energy system, and vigorously support the development of clean energy such as wind energy and solar energy. The southwest region has extremely rich hydropower and natural gas resources. For example, the total installed capacity of hydropower in Sichuan Province and Yunnan Province accounts for more than 40% of the country, and the basic natural gas reserves in Sichuan Province and Chongqing City account for 30% of the country. Under the strategic deployment of "West-to-East Power Transmission" and "West-to-East Gas Transmission", the power grid in the southwest region has become a DC transmission system in the AC / DC hybrid scenario within the region. It not only transmits electricity to the local power grid through the AC power grid, but also provides a large amount of energy for the development of the eastern region through the DC transmission channel. Therefore, the relationship between the source, grid and load in the AC / DC hybrid scenario within the region is complex. At the same time, wind and solar renewable energy have inherent characteristics such as randomness and volatility. As the access scale gradually expands, the problem of insufficient absorption has become more and more obvious. The abandonment rate of wind and solar power in some provinces and cities even exceeds 30%. Therefore, the problem of accommodating new energy in the DC transmission system under the scenario of AC / DC hybrid in the region is highly concerned, and multi-energy complementary integrated optimization projects are encouraged. Based on multi-energy complementarity, multi-energy coordinated supply is achieved to improve the absorption capacity of renewable energy. In addition, the development direction of the development and construction of the integrated system of water, wind and light in the basin is further clarified. The energy structure of the water-rich basin is optimized according to the resource endowment, and wind power, photovoltaic, hydropower and pumped storage power sources are built. The original hydropower is expanded and remodeled, and the corresponding grid facilities are matched. The reasonable optimization and dispatch of cascade hydropower can also play the role of energy storage like pumped storage, so as to form the natural advantage of multi-energy mutual assistance and bundled transmission on the source side, which is one of the important means to implement the new power system. In summary, driven by the development needs, the basic theory and key technologies of the complementary optimization planning of multiple types of clean energy in the DC transmission system under the scenario of AC / DC hybrid in the region are studied, and the regional multi-energy system is constructed to achieve the full absorption of clean energy such as water, wind and light, which has great strategic significance for energy transformation and promoting energy structure adjustment.
[0003] At present, the research on the optimal configuration of the capacity of multiple types of clean energy power generation systems in the DC transmission system under the AC / DC hybrid scenario in the region has the following main deficiencies: (1) In many studies, the energy types of multiple types of clean energy power generation systems are relatively small, and most of them are limited to two or three energy types of hydropower, wind, solar and storage. There is a lack of in-depth research on the complementarity between more types of energy; (2) Most types of clean energy power generation systems only study the capacity configuration of a single hydropower station supporting wind, solar and storage, and lack in-depth research on systems such as basin-wide cascade hydropower stations supporting wind, solar and storage; at the same time, it is impossible to deal with how to linearize the nonlinear constraints related to the hydropower station, resulting in difficulty in solving the capacity configuration of the wind and solar power stations; (3) The current research on the overall structure and working mode of multiple types of clean energy power generation systems in the DC transmission system under the AC / DC hybrid scenario in the region is not clear enough, and it is impossible to establish a capacity planning model. Summary of the invention
[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides an energy capacity optimization method for a DC transmission system in an intra-regional AC / DC hybrid scenario, which solves the problem of unreasonable configuration of wind and solar energy storage capacity in matching the clean energy system with the grid load.
[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a method for optimizing the energy capacity of a DC transmission system in an AC / DC hybrid scenario within a region, comprising:
[0006] Establish the overall structure and power balance working mode of multiple types of clean energy power generation systems in the DC transmission system under the AC / DC hybrid scenario in the region;
[0007] Based on the overall structure and power balance working mode of multi-type clean energy power generation system, the output model of multi-type clean energy power generation system is established;
[0008] According to the output model of multi-type clean energy power generation system, the constraint conditions of multi-type clean energy power generation system are obtained, and the nonlinear constraints are linearized. Taking the optimal planning benefit of multi-type clean energy power generation system as the optimization goal, a mixed integer linear model for the optimal configuration of the capacity of multi-type clean energy power generation system is established;
[0009] Solve the mixed integer linear model for optimal capacity configuration of multi-type clean energy power generation systems and obtain the optimal capacity configuration of wind and solar power stations.
[0010] Furthermore, the overall structure of the multi-type clean energy power generation system includes a supply side and a demand side; the supply side includes hydropower, wind power, photovoltaics and electrochemical energy storage; the demand side includes the local AC grid load and the sending-end grid load of the DC transmission channel; the hydropower, wind power and photovoltaics are the main power suppliers on the supply side; the electrochemical energy storage is used to absorb the excess power of hydropower, wind power and photovoltaic power supply or to make up for the shortage of hydropower, wind power and photovoltaic power supply;
[0011] The power balance working mode of the multi-type clean energy power generation system is specifically:
[0012] For the local AC grid load: the AC grid load power is converted according to the power generation delivered to the AC grid by multiple clean energy power generation systems and the AC grid load demand power to meet the power balance of source and load;
[0013] For the power grid load at the sending end of the DC transmission channel: real-time power balance is required.
[0014] Furthermore, the output models of the multi-type clean energy power generation system include a wind power output model, a photovoltaic output model, a cascade hydropower output model and an energy storage charging and discharging model:
[0015]
[0016]
[0017]
[0018]
[0019]
[0020]
[0021] Where v(t) is the wind speed at the hub of the wind turbine at time t; v wind (t) is the wind speed at the wind measuring point at time t; h is the hub height; h w is the height of the wind measuring point; P w (t) is the output power of the wind turbine at time t; V in is the cut-in wind speed; V out is the cut-out wind speed; P wn is the rated power of the wind turbine; V r is the rated wind speed; P pv (t) is the output power of the photovoltaic battery group at time t; L solar (t) is the solar radiation intensity of the area where the photovoltaic cell is located at time t; m is the derating coefficient of the photovoltaic cell; P pvnis the nominal power of the photovoltaic cell under standard test conditions; a is the power temperature coefficient; T C (t) is the actual working temperature of the photovoltaic cell group at time t; T stc is the standard operating temperature of the photovoltaic cell group; T temp (t) is the ambient temperature of the photovoltaic cell at time t; N oct is the nominal temperature of the photovoltaic battery group; E is the total power generation of the cascade hydropower station during the dispatch period; j is the number of the cascade hydropower station; N h is the total number of cascade hydropower stations; T is the duration of the dispatching cycle; P h,j (t) is the output of the jth cascade hydropower station at time t; Δt is the time step length; k j is the output coefficient of the j-th cascade hydropower station; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; H j (t) is the generating head of the jth cascade hydropower station at time t; E d (t) is the amount of electrochemical energy stored at time t; E d (t-1) is the amount of electrochemical energy stored at time t-1; P ch (t) is the charging power of the electrochemical energy storage at time t; η ch is the charging efficiency of electrochemical energy storage; P dis (t) is the discharge power of electrochemical energy storage at time t; η dis is the discharge efficiency of electrochemical energy storage.
[0022] Furthermore, the constraints of the multi-type clean energy power generation system include reservoir water quantity constraints, hydropower station output constraints, electrochemical energy storage charging and discharging constraints, and power balance constraints of the DC transmission system in the AC / DC hybrid scenario within the region; the expression of the reservoir water quantity constraint is:
[0023] I j (t) = Q j-1 (t-τ)+R j (t)
[0024] V j (t) = V j (t-1)+3600(I j (t)-Q j (t))Δt
[0025] Z j,min ≤Z j (t)≤Z j,max
[0026] Z j (1) = Z j (T)
[0027] Qj,min ≤Q j (t)≤Q j,max
[0028] s j,min ≤s j (t)≤s j,max
[0029]
[0030] V j (t) = f j,zν (Z j (t))
[0031]
[0032] Among them, I j (t) is the inflow of the jth cascade hydropower station at time t; j is the number of the cascade hydropower station; Q j-1 (t-τ) is the power generation flow of the j-1th cascade hydropower station at the time (t-τ); R j (t) is the interval flow between the j-1th cascade hydropower station and the jth cascade hydropower station; V j (t) is the storage capacity of the reservoir where the j-th cascade hydropower station is located at time t; V j (t-1) is the storage capacity of the reservoir where the j-th cascade hydropower station is located at time t-1; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; Δt is the time step; Z j,min is the lower limit of the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j (t) is the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j,max is the upper limit of the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j (1) is the water level in front of the dam at the beginning of daily regulation of the reservoir; Z j (T) is the water level in front of the dam at the end of daily regulation of the reservoir; T is the duration of the dispatching cycle; Q j,min is the lower limit of the power generation flow of the j-th cascade hydropower station at time t; Q j,max is the upper limit of the power generation flow of the jth cascade hydropower station at time t; s j,min is the lower limit of the water discharge of the j-th cascade hydropower station at time t; s j (t) is the water discharge of the jth cascade hydropower station at time t; s j,max H is the upper limit of the water discharge of the j-th cascade hydropower station at time t; j (t) is the generating head of the jth cascade hydropower station at time t; Z j(t-1) is the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t-1; is the tailwater level of the jth cascade hydropower station at time t; f j,zν is the water level-storage capacity relationship function of the reservoir where the j-th cascade hydropower station is located; f j,zu It is the tailwater level discharge relationship function of the reservoir where the j-th cascade hydropower station is located.
[0033] Furthermore, the expression of the hydropower station output constraint is:
[0034]
[0035] Among them, P h,j (t) is the output of the jth cascade hydropower station at time t; f j,pqh It is the binary relationship function between the power output of the hydropower station and the power generation flow and power generation head; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; H j (t) is the generating head of the jth cascade hydropower station at time t; P h,j,min is the lower limit of the output of the jth cascade hydropower station at time t; P h,j (t) is the output of the jth cascade hydropower station at time t; P h,j,max is the upper limit of the output of the jth cascade hydropower station at time t; P h,j (t-1) is the output of the jth cascade hydropower station at time t-1; is the upward climbing capacity of the jth cascade hydropower station; Δt is the time step length; is the downward climbing capacity of the j-th cascade hydropower station.
[0036] Furthermore, the expression of the electrochemical energy storage charge and discharge constraint is:
[0037]
[0038] u ch (t)+u dis (t)≤1,u ch (t),u dis (t)∈{0,1}
[0039] E ESS =k×P ESS =k×δ×(E w +E pv )
[0040] μ min E ESS ≤E d (t)≤μ max E ESS
[0041] E d (1) = E d (T)
[0042] Among them, P ch (t) is the charging power of the electrochemical energy storage at time t; u ch (t) is the energy storage charging state at time t, which is 1 when charging, otherwise 0; is the maximum charging power of electrochemical energy storage at time t; P dis (t) is the discharge power of electrochemical energy storage at time t; u dis (t) is the energy storage discharge state at time t, which is 1 when discharging, otherwise, 0; is the maximum discharge power of electrochemical energy storage at time t; E ESS is the rated capacity of electrochemical energy storage; k is the charging time; P ESS is the rated power of electrochemical energy storage; δ is the energy storage capacity configuration coefficient; E w is the capacity of the planned wind power station; E pv is the capacity of the planned photovoltaic power station; μ min E is the lower limit constraint factor of energy storage; d (t) is the amount of electrochemical energy stored at time t; μ max E is the upper limit constraint factor of energy storage; d (1) is the amount of electrochemical energy stored at the initial moment; E d (T) is the amount of electrochemical energy stored at the final moment.
[0043] Furthermore, the expression of the power balance constraint of the DC transmission system in the AC / DC hybrid scenario in the area is:
[0044]
[0045]
[0046]
[0047]
[0048] Among them, P G (t) is the power generation of the multi-clean energy power generation system at time t; P w (t) is the output power of the wind turbine at time t; P pv (t) is the output power of the photovoltaic battery group at time t; j is the number of the cascade hydropower station; N h is the total number of hydropower stations; P h,j (t) is the output of the jth cascade hydropower station at time t; P dis(t) is the discharge power of electrochemical energy storage at time t; P ch (t) is the charging power of the electrochemical energy storage at time t; The power generation power of the DC sending-end grid is sent to the power generation system; Send the power generated by the AC grid to the power generation system; The load demand power of the power grid at the sending end served by the DC transmission channel; The load demand power of the local AC power grid; The total power generation delivered to the AC grid by multiple clean energy power generation systems; E L is the total load demand of the local AC power grid.
[0049] Furthermore, the linearization of the nonlinear constraint is specifically: linearizing the nonlinear constraint in the hydropower station output constraint to obtain the hydropower station output constraint after linearization:
[0050]
[0051]
[0052]
[0053]
[0054]
[0055]
[0056] in, is the head discrete interval indicator variable, which is 1 if the unit generating head is within the kth head sub-interval, otherwise, it is 0; is the k-1th water head sub-interval of the jth cascade hydropower station; H j is the jth cascade hydropower station; is the kth water head sub-interval of the jth cascade hydropower station; k is the water head sub-interval number; P h,j,max is the upper limit of the output of the j-th cascade hydropower station at time t; is the head discrete interval indicator variable indicating whether the unit's generating head is within the first head sub-interval; P h,j is the output of the jth cascade hydropower station; is the functional relationship between the output and the power generation flow in the first head sub-interval; Q j is the power generation flow of the jth cascade hydropower station; is a water head discrete interval indicator variable indicating whether the generating water head of the unit is within the second water head sub-interval; is the functional relationship between the output and the power generation flow in the second head sub-interval; is a water head discrete interval indicator variable indicating whether the generating water head of the unit is within the third water head sub-interval; It is the functional relationship between the output and the power generation flow in the third head sub-interval.
[0057] Furthermore, the objective function of the mixed integer linear model for optimal configuration of the multi-type clean energy power generation system capacity is expressed as:
[0058] max C=C sell -C inv -C ope
[0059] C ope =C a +C ESS
[0060]
[0061]
[0062]
[0063]
[0064]
[0065] Among them, max is the maximum value function; C is the total planned benefit; C sell is the income from electricity sales; C inv is the construction cost; C ope is the annual operating cost; C a is the cost of power abandonment; C ESS The cost of charging and discharging energy storage; is the unit price of wind power; T is the duration of the dispatch cycle; P w (t) is the output power of the wind turbine at time t; is the unit price of photovoltaic electricity; P pv (t) is the output power of the photovoltaic battery group at time t; P is the unit price of hydropower; h,j (t) is the output of the jth cascade hydropower station in period t; j is the number of the cascade hydropower station; N h is the total number of cascade hydropower stations; f is the depreciation coefficient; is the construction cost per unit installed capacity of the wind power station; E is the annual operation and maintenance cost per unit installed capacity of the wind power station; w To plan the capacity of wind power plants; is the construction cost per unit installed capacity of the photovoltaic power station; E is the annual operation and maintenance cost per unit installed capacity of the photovoltaic power station;pv is the planned capacity of the photovoltaic power station; r is the discount rate; m is the operating life; c wa P is the penalty cost unit price for wind curtailment; wa (t) is the abandoned power of the wind power station at time t; c pva P is the penalty cost unit price for abandoning light; pva (t) is the abandoned power of the photovoltaic power station at time t; c ha is the penalty cost unit price for abandoned water; j (t) is the water discharge of the jth cascade hydropower station at time t; c ESS P is the unit price of energy storage charging and discharging cost; ch (t) is the charging power of the electrochemical energy storage at time t; P dis (t) is the discharge power of the electrochemical energy storage at time t.
[0066] The beneficial effects of the present invention are as follows: the multi-type clean energy system of the present invention includes four energy forms: hydropower, wind power, photovoltaics and energy storage. It fully considers the natural complementary characteristics of water, wind and solar resources and the peak-shaving capacity of energy storage, realizes the selection of the optimal capacity of wind and solar new energy and electrochemical energy storage, and solves the problem of unreasonable configuration of wind and solar energy storage capacity in matching the clean energy system with the power grid load. BRIEF DESCRIPTION OF THE DRAWINGS
[0067] Figure 1 The present invention is a flow chart of the method.
[0068] Figure 2 It is a schematic diagram of the overall structure of the system of the present invention and the working mode of power balance.
[0069] Figure 3 It is a schematic diagram of the capacity optimization model of the multi-type clean energy power generation system of the present invention.
[0070] Figure 4 This is a flow chart for solving the capacity optimization model of the present invention.
[0071] Figure 5 This is a source-grid-load structure diagram of the DC transmission system under AC / DC hybrid connection within the region of the present invention.
[0072] Figure 6 It is a schematic diagram of the AC power grid load and DC sending end load demand curve of the present invention.
[0073] Figure 7 This is a diagram showing the complementary power outputs of water, wind and solar power in the multi-type clean energy system of the present invention.
[0074] Figure 8 This is a schematic diagram of the matching of each energy output and total load of the multi-type clean energy system of the present invention. DETAILED DESCRIPTION
[0075] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.
[0076] like Figure 1 As shown, in one embodiment of the present invention, a method for optimizing the energy capacity of a DC transmission system in an intra-regional AC / DC hybrid scenario includes:
[0077] Establish the overall structure and power balance working mode of multiple types of clean energy power generation systems in the DC transmission system under the AC / DC hybrid scenario in the region;
[0078] Based on the overall structure and power balance working mode of multi-type clean energy power generation system, the output model of multi-type clean energy power generation system is established;
[0079] According to the output model of multi-type clean energy power generation system, the constraint conditions of multi-type clean energy power generation system are obtained, and the nonlinear constraints are linearized. Taking the optimal planning benefit of multi-type clean energy power generation system as the optimization goal, a mixed integer linear model for the optimal configuration of the capacity of multi-type clean energy power generation system is established;
[0080] Solve the mixed integer linear model for optimal capacity configuration of multi-type clean energy power generation systems and obtain the optimal capacity configuration of wind and solar power stations.
[0081] The overall structure of the multi-type clean energy power generation system includes a supply side and a demand side; the supply side includes hydropower, wind power, photovoltaics and electrochemical energy storage; the demand side includes the local AC grid load and the sending-end grid load of the DC transmission channel; the hydropower, wind power and photovoltaics are the main power suppliers on the supply side; the electrochemical energy storage is used to absorb the excess power of hydropower, wind power and photovoltaic power supply or to make up for the shortage of hydropower, wind power and photovoltaic power supply;
[0082] The power balance working mode of the multi-type clean energy power generation system is specifically:
[0083] For the local AC grid load: the AC grid load power is converted according to the power generation delivered to the AC grid by multiple clean energy power generation systems and the AC grid load demand power to meet the power balance of source and load;
[0084] For the power grid load at the sending end of the DC transmission channel: real-time power balance is required.
[0085] like Figure 2The overall structure of the system shown and the working mode of power balance can reflect the relationship between the power generation system, the local load and the DC sending-end load. The overall structure is as follows: the supply side is the clean energy hydropower, wind power, photovoltaics and electrochemical energy storage in the multi-type clean energy power generation system. The main supply of electricity is generated by hydropower, wind power and photovoltaics according to natural conditions, and electrochemical energy storage absorbs excess electricity or makes up for the shortage; the demand side is the local AC power grid load and the sending-end power grid load of the DC transmission channel. The power balance working mode is as follows: the total load demand of the local AC power grid is large, and the power balance of the source and load can be met after the AC power grid load power is converted according to the power generation sent to the AC power grid by this clean energy power generation system and the AC power grid load demand, while the sending-end power grid load demand served by the DC transmission channel requires real-time power balance.
[0086] In this embodiment, the output model of the mixed integer linear model for optimal configuration of capacity of multi-type clean energy power generation systems is the output model of multi-type clean energy power generation systems, the constraints are the constraints of the multi-type clean energy power generation systems after linearization, and the optimization goal is to optimize the planning benefits of multi-type clean energy power generation systems.
[0087] like Figure 3 As shown, the output models of the multi-type clean energy power generation system include a wind power output model, a photovoltaic output model, a cascade hydropower output model and an energy storage charging and discharging model:
[0088]
[0089]
[0090]
[0091]
[0092]
[0093]
[0094] Where v(t) is the wind speed at the hub of the wind turbine at time t; v wind (t) is the wind speed at the wind measuring point at time t; h is the hub height; h w is the height of the wind measuring point; P w (t) is the output power of the wind turbine at time t; V in is the cut-in wind speed; V out is the cut-out wind speed; P wn is the rated power of the wind turbine; V r is the rated wind speed; P pv (t) is the output power of the photovoltaic battery group at time t; Lsolar (t) is the solar radiation intensity of the area where the photovoltaic cell is located at time t; m is the derating coefficient of the photovoltaic cell; P pvn is the nominal power of the photovoltaic cell under standard test conditions; a is the power temperature coefficient; T C (t) is the actual working temperature of the photovoltaic cell group at time t; T stc is the standard operating temperature of the photovoltaic cell group; T temp (t) is the ambient temperature of the photovoltaic cell at time t; N oct is the nominal temperature of the photovoltaic battery group; E is the total power generation of the cascade hydropower station during the dispatch period; j is the number of the cascade hydropower station; N h is the total number of cascade hydropower stations; T is the duration of the dispatching cycle; P h,j (t) is the output of the jth cascade hydropower station at time t; Δt is the time step length; k j is the output coefficient of the j-th cascade hydropower station; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; H j (t) is the generating head of the jth cascade hydropower station at time t; E d (t) is the amount of electrochemical energy stored at time t; E d (t-1) is the amount of electrochemical energy stored at time t-1; P ch (t) is the charging power of the electrochemical energy storage at time t; η ch is the charging efficiency of electrochemical energy storage; P dis (t) is the discharge power of electrochemical energy storage at time t; η dis is the discharge efficiency of electrochemical energy storage.
[0095] The constraints of the multi-type clean energy power generation system include reservoir water volume constraints, hydropower station output constraints, electrochemical energy storage charging and discharging constraints, and power balance constraints of the DC transmission system in the AC / DC hybrid scenario within the region; Figure 3 As shown, the expression of the reservoir water quantity constraint is:
[0096] I j (t) = Q j-1 (t-τ)+R j (t)
[0097] V j (t) = V j (t-1)+3600(I j (t)-Q j (t))Δt
[0098] Z j,min ≤Z j (t)≤Z j,max
[0099] Z j (1) = Z j (T)
[0100] Q j,min ≤Q j (t)≤Q j,max
[0101] s j,min ≤s j (t)≤s j,max
[0102]
[0103] V j (t) = f j,zν (Z j (t))
[0104]
[0105] Among them, I j (t) is the inflow of the jth cascade hydropower station at time t; j is the number of the cascade hydropower station; Q j-1 (t-τ) is the power generation flow of the j-1th cascade hydropower station at the time (t-τ); R j (t) is the interval flow between the j-1th cascade hydropower station and the jth cascade hydropower station; V j (t) is the storage capacity of the reservoir where the j-th cascade hydropower station is located at time t; V j (t-1) is the storage capacity of the reservoir where the j-th cascade hydropower station is located at time t-1; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; Δt is the time step; Z j,min is the lower limit of the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j (t) is the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j,max is the upper limit of the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j (1) is the water level in front of the dam at the beginning of daily regulation of the reservoir; Z j (T) is the water level in front of the dam at the end of daily regulation of the reservoir; T is the duration of the dispatching cycle; Q j,min is the lower limit of the power generation flow of the j-th cascade hydropower station at time t; Q j,max is the upper limit of the power generation flow of the jth cascade hydropower station at time t; s j,min is the lower limit of the water discharge of the j-th cascade hydropower station at time t; s j (t) is the water discharge of the jth cascade hydropower station at time t; s j,max H is the upper limit of the water discharge of the j-th cascade hydropower station at time t;j (t) is the generating head of the jth cascade hydropower station at time t; Z j (t-1) is the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t-1; is the tailwater level of the jth cascade hydropower station at time t; f j,zν is the water level-storage capacity relationship function of the reservoir where the j-th cascade hydropower station is located; f j,zu It is the tailwater level discharge relationship function of the reservoir where the j-th cascade hydropower station is located.
[0106] like Figure 3 As shown, the expression of the hydropower station output constraint is:
[0107]
[0108] Among them, P h,j (t) is the output of the jth cascade hydropower station at time t; f j,pqh It is the binary relationship function between the power output of the hydropower station and the power generation flow and power generation head; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; H j (t) is the generating head of the jth cascade hydropower station at time t; P h,j,min is the lower limit of the output of the jth cascade hydropower station at time t; P h,j (t) is the output of the jth cascade hydropower station at time t; P h,j,max is the upper limit of the output of the jth cascade hydropower station at time t; P h,j (t-1) is the output of the jth cascade hydropower station at time t-1; is the upward climbing capacity of the jth cascade hydropower station; Δt is the time step length; is the downward climbing capacity of the j-th cascade hydropower station.
[0109] like Figure 3 As shown, the expression of the electrochemical energy storage charge and discharge constraint is:
[0110]
[0111] u ch (t)+u dis (t)≤1,u ch (t),u dis (t)∈{0,1}
[0112] E ESS =k×P ESS =k×δ×(E w +E pv )
[0113] μ minE ESS ≤E d (t)≤μ max E ESS
[0114] E d (1) = E d (T)
[0115] Among them, P ch (t) is the charging power of the electrochemical energy storage at time t; u ch (t) is the energy storage charging state at time t, which is 1 when charging, otherwise 0; is the maximum charging power of electrochemical energy storage at time t; P dis (t) is the discharge power of electrochemical energy storage at time t; u dis (t) is the energy storage discharge state at time t, which is 1 when discharging, otherwise, 0; is the maximum discharge power of electrochemical energy storage at time t; E ESS is the rated capacity of electrochemical energy storage; k is the charging time; P ESS is the rated power of electrochemical energy storage; δ is the energy storage capacity configuration coefficient; E w is the capacity of the planned wind power station; E pv is the capacity of the planned photovoltaic power station; μ min E is the lower limit constraint factor of energy storage; d (t) is the amount of electrochemical energy stored at time t; μ max E is the upper limit constraint factor of energy storage; d (1) is the amount of electrochemical energy stored at the initial moment; E d (T) is the amount of electrochemical energy stored at the final moment.
[0116] like Figure 3 As shown, the expression of the power balance constraint of the DC transmission system in the AC / DC hybrid scenario in the area is:
[0117]
[0118]
[0119]
[0120]
[0121] Among them, P G (t) is the power generation of the multi-clean energy power generation system at time t; P w (t) is the output power of the wind turbine at time t; P pv (t) is the output power of the photovoltaic battery group at time t; j is the number of the cascade hydropower station; Nh is the total number of hydropower stations; P h,j (t) is the output of the jth cascade hydropower station at time t; P dis (t) is the discharge power of electrochemical energy storage at time t; P ch (t) is the charging power of the electrochemical energy storage at time t; The power generation power of the DC sending-end grid is sent to the power generation system; Send the power generated by the AC grid to the power generation system; The load demand power of the power grid at the sending end served by the DC transmission channel; The load demand power of the local AC power grid; The total power generation delivered to the AC grid by multiple clean energy power generation systems; E L is the total load demand of the local AC power grid.
[0122] like Figure 3 As shown, the linearization of the nonlinear constraint is specifically: linearizing the nonlinear constraint in the hydropower station output constraint to obtain the hydropower station output constraint after linearization:
[0123]
[0124]
[0125]
[0126]
[0127]
[0128]
[0129] in, is the head discrete interval indicator variable, which is 1 if the unit generating head is within the kth head sub-interval, otherwise, it is 0; is the k-1th water head sub-interval of the jth cascade hydropower station; H j is the jth cascade hydropower station; is the kth water head sub-interval of the jth cascade hydropower station; k is the water head sub-interval number; P h,j,max is the upper limit of the output of the j-th cascade hydropower station at time t; is the head discrete interval indicator variable indicating whether the unit's generating head is within the first head sub-interval; P h,j is the output of the jth cascade hydropower station; is the functional relationship between the output and the power generation flow in the first head sub-interval; Q j is the power generation flow of the jth cascade hydropower station; is a water head discrete interval indicator variable indicating whether the generating water head of the unit is within the second water head sub-interval; is the functional relationship between the output and the power generation flow in the second head sub-interval; is a water head discrete interval indicator variable indicating whether the generating water head of the unit is within the third water head sub-interval; It is the functional relationship between the output and the power generation flow in the third head sub-interval.
[0130] In this embodiment, the processing model of the mixed integer linear model for optimal configuration of capacity of multi-type clean energy power generation systems is the output model of multi-type clean energy power generation systems, the constraints are the constraints of the multi-type clean energy power generation systems after linearization processing, and the optimization goal is to optimize the planning benefits of multi-type clean energy power generation systems.
[0131] like Figure 3 As shown, in the mixed integer linear model for optimal configuration of the capacity of the multi-type clean energy power generation system, the method for linearizing the nonlinear constraints in the reservoir water quantity constraints is as follows:
[0132] Linearization of dam-front water level and reservoir capacity: Reservoir capacity is a nonlinear function of dam-front water level. When the dispatching period is 1 day, for reservoirs above daily regulation, the fluctuation of dam-front water level and reservoir capacity within 1 day is very small. Therefore, for these reservoirs, linear approximation is performed in the interval near the initial water level of the reservoir to express: where a j 、b j are the constants for the conversion between the water level in front of the dam and the reservoir capacity of the j-th cascade hydropower station.
[0133] Linearization of unit dynamic characteristics: Unit dynamic characteristic equation P h,j (t) = f j,pqh (Q j (t),H j (t)) is the binary relationship function between the output of cascade hydropower station j and the power generation flow Q and power generation head H variables. Since the cascade hydropower stations and units participating in the peak load regulation of the power grid have large changes in head during the dispatch period, the influence of head changes cannot be ignored. The detailed process of linearizing the unit dynamic characteristic curve is as follows:
[0134] (1) Unit generating head dispersion
[0135] by The interval is divided into three continuous water head sub-intervals, namely and in and Corresponding to the lower head and the higher head respectively, the generating head of the unit j of the cascade hydropower station at any time must satisfy the following constraints:
[0136]
[0137]
[0138]
[0139] Where: is the head discrete interval indicator variable, Indicates that the generating head of the unit is within the kth head sub-interval;
[0140] (2) Dynamic characteristic curve of head-related units
[0141] After the water head interval is discretized, it is necessary to select a unit power characteristic curve as a representative in each water head interval. This process is called the water head associated unit power characteristic curve. When the unit power characteristic curve under the average water head is selected as the representative, and the curve is linearized, the mathematical expression of the relationship between the unit power characteristic curve and the water head is constructed as follows:
[0142]
[0143]
[0144]
[0145] Where: is the functional relationship between the output and the power generation flow in the kth water head sub-interval;
[0146] According to the constraint and It can be seen that there is only one Assumptions at this time Simultaneous Constraint and Been relaxed, only the constraint To be an effective constraint, The simplification of the unit's dynamic characteristics is effectively achieved.
[0147] like Figure 3 As shown, the objective function of the mixed integer linear model for optimal configuration of the multi-type clean energy power generation system capacity is expressed as:
[0148] max C=C sell -C inv -C ope
[0149]
[0150]
[0151]
[0152]
[0153]
[0154]
[0155] Among them, max is the maximum value function; C is the total planned benefit; C sell is the income from electricity sales; C inv is the construction cost; C ope is the annual operating cost; C a is the cost of power abandonment; C ESS The cost of charging and discharging energy storage; is the unit price of wind power; T is the duration of the dispatch cycle; P w (t) is the output power of the wind turbine at time t; is the unit price of photovoltaic electricity; P pv (t) is the output power of the photovoltaic battery group at time t; P is the unit price of hydropower; h,j (t) is the output of the jth cascade hydropower station in period t; j is the number of the cascade hydropower station; N h is the total number of cascade hydropower stations; f is the depreciation coefficient; is the construction cost per unit installed capacity of the wind power station; E is the annual operation and maintenance cost per unit installed capacity of the wind power station; w To plan the capacity of wind power plants; is the construction cost per unit installed capacity of the photovoltaic power station; E is the annual operation and maintenance cost per unit installed capacity of the photovoltaic power station; pv is the planned capacity of the photovoltaic power station; r is the discount rate; m is the operating life; c wa P is the penalty cost unit price for wind curtailment; wa (t) is the abandoned power of the wind power station at time t; c pva P is the penalty cost unit price for abandoning light; pva (t) is the abandoned power of the photovoltaic power station at time t; c ha is the penalty cost unit price for abandoned water; j (t) is the water discharge of the jth cascade hydropower station at time t; c ESS P is the unit price of energy storage charging and discharging cost; ch (t) is the charging power of the electrochemical energy storage at time t; Pdis (t) is the discharge power of the electrochemical energy storage at time t.
[0156] In this embodiment, Figure 4 The figure shows the solution process of the capacity optimization configuration model of the present invention. Specifically: first input the parameter information of the model, including planning economic parameters, basic parameters of hydropower stations, and basic parameters of electrochemical energy storage; then take the optimal planning benefits of multiple types of clean energy power generation systems as the optimization target, among which the installed capacity of wind power systems, the installed capacity of photovoltaic systems, and the peak-shaving operation conditions of hydropower systems are optimization variables; take the water volume constraints of reservoirs, the output constraints of hydropower stations, the charging and discharging constraints of electrochemical energy storage, and the power balance constraints of DC transmission systems in the AC / DC hybrid scenario within the region as constraint conditions, and linearize the nonlinear constraints to finally construct a mixed integer linear programming model, and finally optimize and solve it in Matlab through the Cplex solver to obtain the optimal capacity configuration of wind, solar and energy storage.
[0157] Based on the above considerations, the optimal configuration method of wind and solar capacity in multiple types of clean energy power generation systems in the DC transmission system under the AC / DC hybrid scenario in the region is used. A planning scheme for the capacity of supporting wind and solar power stations is made for the DC transmission system under the AC / DC scenario in the region, which is built on the basis of the three cascade hydropower stations of Jinxi, Jindong and Guandi in the lower reaches of the Yalong River Basin. The structure diagram is shown in the figure below. Figure 5 As shown in the figure, the natural condition data of four typical days in a year in the local area are used as an example for detailed explanation.
[0158] In this embodiment, the load demand curve of the local Sichuan power grid and the load demand curve of the DC sending end Central China power grid are as follows: Figure 6 As shown, according to the capacity optimization model introduced above, the wind and solar capacities of various types of clean energy power generation systems in the DC transmission system under the AC / DC hybrid scenario in the area are optimized, and the optimal planning results and various target values are shown in Tables 1 and 2.
[0159] Table 1 Optimal installed capacity of wind and solar power
[0160] type Installed capacity Wind power 5410(MW) Photovoltaic 4470(MW)
[0161] Table 2 Target values
[0162] Target Value (unit) Total scale of wind and solar power 11689(MW) Revenue from electricity sales 4.55 billion yuan Total planning cost 5.3 (100 million yuan) Annual operating costs 0.08 (100 million yuan) Abandonment rate of wind and solar 0.32％
[0163] Based on this planning scheme, the renewable energy output of the multi-energy complementary power generation system in a typical scenario is obtained as follows: Figure 7As shown, it can be seen that the photovoltaic system has output only during the daytime due to the influence of light intensity, and the output power at night is 0; wind power has a certain output throughout the day; the peak section of hydropower output power is in the valley section of the wind power output curve. It can be seen that the three renewable energy sources of wind, solar and water have natural complementary characteristics in time. The matching situation of each energy output and total load of the multi-type clean energy system of the present invention
[0164] The power curves of each energy source and the total load power curve of the system are obtained as follows: Figure 8 As shown, it can be seen that in a typical scenario, the power curve provided by the system is well consistent with the load power curve, and it can be seen from Table 2 that the wind and solar power abandonment rate is only 0.32%, that is, in this capacity configuration scheme, the multi-type clean energy power generation system in the DC transmission system in the AC / DC hybrid scenario in the area has a good ability to absorb new energy power generation.
Claims
1. A method for optimizing the energy capacity of a DC transmission system in an AC / DC hybrid scenario within a region, characterized in that: include: Establish the overall structure and power balance working mode of multiple types of clean energy power generation systems in the DC transmission system under the AC / DC hybrid scenario in the region; Based on the overall structure and power balance working mode of multi-type clean energy power generation system, the output model of multi-type clean energy power generation system is established; According to the output model of multi-type clean energy power generation system, the constraint conditions of multi-type clean energy power generation system are obtained, and the nonlinear constraints are linearized. Taking the optimal planning benefit of multi-type clean energy power generation system as the optimization goal, a mixed integer linear model for the optimal configuration of the capacity of multi-type clean energy power generation system is established; Solve the mixed integer linear model for optimal capacity configuration of multi-type clean energy power generation systems and obtain the optimal capacity configuration of wind and solar power stations.
2. According to claim 1, the method for optimizing the energy capacity of the DC transmission system in the AC / DC hybrid scenario within the region is characterized in that: The overall structure of the multi-type clean energy power generation system includes a supply side and a demand side; the supply side includes hydropower, wind power, photovoltaics and electrochemical energy storage; the demand side includes the local AC grid load and the sending-end grid load of the DC transmission channel; the hydropower, wind power and photovoltaics are the main power suppliers on the supply side; the electrochemical energy storage is used to absorb the excess power of hydropower, wind power and photovoltaic power supply or to make up for the shortage of hydropower, wind power and photovoltaic power supply; The power balance working mode of the multi-type clean energy power generation system is specifically: For the local AC grid load: after converting the AC grid load power according to the power generation delivered to the AC grid by multiple clean energy power generation systems and the AC grid load demand, the power balance between source and load is met; For the power grid load at the sending end of the DC transmission channel: real-time power balance is required.
3. According to claim 1, the method for optimizing the energy capacity of the DC transmission system in the AC / DC hybrid scenario within the region is characterized in that: The output models of the multi-type clean energy power generation system include a wind power output model, a photovoltaic output model, a cascade hydropower output model, and an energy storage charging and discharging model: Where v(t) is the wind speed at the hub of the wind turbine at time t; v wind (t) is the wind speed at the wind measuring point at time t; h is the hub height; h w is the height of the wind measuring point; P w (t) is the output power of the wind turbine at time t; V in is the cut-in wind speed; V out is the cut-out wind speed; P wn is the rated power of the wind turbine; V r is the rated wind speed; P pv (t) is the output power of the photovoltaic battery group at time t; L solar (t) is the solar radiation intensity of the area where the photovoltaic cell is located at time t; m is the derating coefficient of the photovoltaic cell; P pvn is the nominal power of the photovoltaic cell under standard test conditions; a is the power temperature coefficient; T C (t) is the actual working temperature of the photovoltaic cell group at time t; T stc is the standard operating temperature of the photovoltaic cell group; T temp (t) is the ambient temperature of the photovoltaic cell at time t; N oct is the nominal temperature of the photovoltaic battery group; E is the total power generation of the cascade hydropower station during the dispatch period; j is the number of the cascade hydropower station; N h is the total number of cascade hydropower stations; T is the duration of the dispatching cycle; P h,j (t) is the output of the jth cascade hydropower station at time t; Δt is the time step length; k j is the output coefficient of the j-th cascade hydropower station; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; H j (t) is the generating head of the jth cascade hydropower station at time t; E d (t) is the amount of electrochemical energy stored at time t; E d (t-1) is the amount of electrochemical energy stored at time t-1; P ch (t) is the charging power of the electrochemical energy storage at time t; η ch is the charging efficiency of electrochemical energy storage; P dis (t) is the discharge power of electrochemical energy storage at time t; η dis is the discharge efficiency of electrochemical energy storage.
4. According to claim 1, the method for optimizing the energy capacity of the DC transmission system in the AC / DC hybrid scenario within the region is characterized in that: The constraints of the multi-type clean energy power generation system include reservoir water quantity constraints, hydropower station output constraints, electrochemical energy storage charging and discharging constraints, and power balance constraints of the DC transmission system in the AC / DC hybrid scenario within the region; the expression of the reservoir water quantity constraint is: I j (t)=Q j-1 (t-τ)+R j (t) V j (t)=V j (t-1)+3600(I j (t)-Q j (t))Δt Z j,min ≤Z j (t)≤Z j,max Z j (1)=Z j (T) Q j,min ≤Q j (t)≤Q j,max s j,min ≤s j (t)≤s j,max V j (t)=f j,zν (Z j (t)) Among them, I j (t) is the inflow of the jth cascade hydropower station at time t; j is the number of the cascade hydropower station; Q j-1 (t-τ) is the power generation flow of the j-1th cascade hydropower station at the time (t-τ); R j (t) is the interval flow between the j-1th cascade hydropower station and the jth cascade hydropower station; V j (t) is the storage capacity of the reservoir where the j-th cascade hydropower station is located at time t; V j (t-1) is the storage capacity of the reservoir where the j-th cascade hydropower station is located at time t-1; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; Δt is the time step; Z j,min is the lower limit of the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j (t) is the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j,max is the upper limit of the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t; Z j (1) is the water level in front of the dam at the beginning of daily regulation of the reservoir; Z j (T) is the water level in front of the dam at the end of daily regulation of the reservoir; T is the duration of the dispatching cycle; Q j,min is the lower limit of the power generation flow of the j-th cascade hydropower station at time t; Q j,max is the upper limit of the power generation flow of the jth cascade hydropower station at time t; s j,min is the lower limit of the water discharge of the j-th cascade hydropower station at time t; s j (t) is the water discharge of the jth cascade hydropower station at time t; s j,max H is the upper limit of the water discharge of the j-th cascade hydropower station at time t; j (t) is the generating head of the jth cascade hydropower station at time t; Z j (t-1) is the water level in front of the dam of the reservoir where the j-th cascade hydropower station is located at time t-1; is the tailwater level of the jth cascade hydropower station at time t; f j,zν is the water level-storage capacity relationship function of the reservoir where the j-th cascade hydropower station is located; f j,zu It is the tailwater level discharge relationship function of the reservoir where the j-th cascade hydropower station is located.
5. According to claim 4, the method for optimizing the energy capacity of the DC transmission system in the AC / DC hybrid scenario within the region is characterized in that: The expression of the hydropower station output constraint is: Among them, P h,j (t) is the output of the jth cascade hydropower station at time t; f j,pqh It is the binary relationship function between the power output of the hydropower station and the power generation flow and power generation head; Q j (t) is the power generation flow of the jth cascade hydropower station at time t; H j (t) is the generating head of the jth cascade hydropower station at time t; P h,j,min is the lower limit of the output of the jth cascade hydropower station at time t; P h,j (t) is the output of the jth cascade hydropower station at time t; P h,j,max is the upper limit of the output of the jth cascade hydropower station at time t; P h,j (t-1) is the output of the jth cascade hydropower station at time t-1; is the upward climbing capacity of the jth cascade hydropower station; Δt is the time step length; is the downward climbing capacity of the j-th cascade hydropower station.
6. The method for optimizing the energy capacity of a DC transmission system in an AC / DC hybrid scenario in a region according to claim 4 is characterized in that: The expression of the electrochemical energy storage charge and discharge constraint is: u ch (t)+u dis (t)≤1,u ch (t),u dis (t)∈{0,1} AND ESS =k×P ESS =k×δ×(E w +E pv ) μ min And ESS ≤E d (t)≤μ max And ESS AND d (1)=And d (T) Among them, P ch (t) is the charging power of the electrochemical energy storage at time t; u ch (t) is the energy storage charging state at time t, which is 1 when charging, otherwise 0; is the maximum charging power of electrochemical energy storage at time t; P dis (t) is the discharge power of electrochemical energy storage at time t; u dis (t) is the energy storage discharge state at time t, which is 1 when discharging, otherwise, 0; is the maximum discharge power of electrochemical energy storage at time t; E ESS is the rated capacity of electrochemical energy storage; k is the charging time; P ESS is the rated power of electrochemical energy storage; δ is the energy storage capacity configuration coefficient; E w is the capacity of the planned wind power station; E pv is the capacity of the planned photovoltaic power station; μ min E is the lower limit constraint factor of energy storage; d (t) is the amount of electrochemical energy stored at time t; μ max E is the upper limit constraint factor of energy storage; d (1) is the amount of electrochemical energy stored at the initial moment; E d (T) is the amount of electrochemical energy stored at the final moment.
7. The method for optimizing the energy capacity of a DC transmission system in an AC / DC hybrid scenario in a region according to claim 4 is characterized in that: The expression of the power balance constraint of the DC transmission system in the AC / DC hybrid scenario in the area is: Among them, P G (t) is the power generation of the multi-clean energy power generation system at time t; P w (t) is the output power of the wind turbine at time t; P pv (t) is the output power of the photovoltaic battery group at time t; j is the number of the cascade hydropower station; N h is the total number of hydropower stations; P h,j (t) is the output of the jth cascade hydropower station at time t; P dis (t) is the discharge power of electrochemical energy storage at time t; P ch (t) is the charging power of the electrochemical energy storage at time t; The power generation power of the DC sending-end grid is sent to the power generation system; Send the power generated by the AC grid to the power generation system; The load demand power of the power grid at the sending end served by the DC transmission channel; The load demand power of the local AC power grid; The total power generation delivered to the AC grid by multiple clean energy power generation systems; E L is the total load demand of the local AC power grid.
8. The energy capacity optimization method of the DC transmission system in the AC / DC hybrid scenario in the region according to claim 1 is characterized in that: The linearization of the nonlinear constraints is specifically: linearizing the nonlinear constraints in the hydropower station output constraints to obtain the hydropower station output constraints after linearization: in, is the head discrete interval indicator variable, which is 1 if the unit generating head is within the kth head sub-interval, otherwise, it is 0; is the k-1th water head sub-interval of the jth cascade hydropower station; H j is the jth cascade hydropower station; is the kth water head sub-interval of the jth cascade hydropower station; k is the water head sub-interval number; P h,j,max is the upper limit of the output of the j-th cascade hydropower station at time t; is the head discrete interval indicator variable indicating whether the unit's generating head is within the first head sub-interval; P h,j is the output of the jth cascade hydropower station; is the functional relationship between the output and the power generation flow in the first head sub-interval; Q j is the power generation flow of the jth cascade hydropower station; is a water head discrete interval indicator variable indicating whether the generating water head of the unit is within the second water head sub-interval; is the functional relationship between the output and the power generation flow in the second head sub-interval; is a water head discrete interval indicator variable indicating whether the generating water head of the unit is within the third water head sub-interval; It is the functional relationship between the output and the power generation flow in the third head sub-interval.
9. The method for optimizing the energy capacity of a DC transmission system in an AC / DC hybrid scenario in a region according to claim 1 is characterized in that: The objective function of the mixed integer linear model for optimal configuration of the multi-type clean energy power generation system capacity is expressed as: maxC=C sell -C inv -C ope C ope =C a +C ESS Among them, max is the maximum value function; C is the total planned benefit; C sell is the income from electricity sales; C inv is the construction cost; C ope is the annual operating cost; C a is the cost of power abandonment; C ESS The cost of charging and discharging energy storage; is the unit price of wind power; T is the duration of the dispatch cycle; P w (t) is the output power of the wind turbine at time t; is the unit price of photovoltaic electricity; P pv (t) is the output power of the photovoltaic battery group at time t; P is the unit price of hydropower; h,j (t) is the output of the jth cascade hydropower station in period t; j is the number of the cascade hydropower station; N h is the total number of cascade hydropower stations; f is the depreciation coefficient; is the construction cost per unit installed capacity of the wind power station; E is the annual operation and maintenance cost per unit installed capacity of the wind power station; w To plan the capacity of wind power plants; is the construction cost per unit installed capacity of the photovoltaic power station; E is the annual operation and maintenance cost per unit installed capacity of the photovoltaic power station; pv is the planned capacity of the photovoltaic power station; r is the discount rate; m is the operating life; c wa P is the penalty cost unit price for wind curtailment; wa (t) is the abandoned power of the wind power station at time t; c pva P is the penalty cost unit price for abandoning light; pva (t) is the abandoned power of the photovoltaic power station at time t; c ha is the penalty cost unit price for abandoned water; j (t) is the water discharge of the jth cascade hydropower station at time t; c ESS P is the unit price of energy storage charging and discharging cost; ch (t) is the charging power of the electrochemical energy storage at time t; P dis (t) is the discharge power of the electrochemical energy storage at time t.