Regional planning analysis method with water and electricity reversible transformation

Abstract

The invention relates to a regional planning analysis method with water and electricity reversible transformation, and the method comprises the following steps: S1, screening hydropower stations in an analysis region, and removing hydropower stations which are obviously not suitable for reversible transformation; s2, optimizing the planning model by minimizing the total cost of the power system; and S3, inputting related parameters and data of various units, and solving and analyzing by using the planning model. A new analysis thought is provided for reversible transformation of the regional hydropower station, and a specific transformation scheme of the hydropower station in the region can be provided according to the planning analysis method.

Description

Technical Field

[0001] The present invention relates to the field of electrical engineering, and more specifically to a regional planning analysis method with reversible hydropower transformation. Background Art

[0002] Conventional hydropower units have limited regulation capabilities. Generally, they cannot actively absorb excess electricity during the low-load period of the system, and even a large amount of water abandonment may occur. However, by adding pumped storage units and pump turbines, conventional hydropower stations can be equipped with the ability of pumped storage regulation, promoting the optimal regulation of resources in time, and achieving the purpose of peak shaving and valley filling. Moreover, the development cost of reversible transformation based on existing hydropower stations is much lower than that of directly building new pumped storage stations, and the transformation potential is huge. However, in a large area, how to evaluate which hydropower stations can be reversibly transformed, how to evaluate the capacity of reversible units required for reversible transformation of a hydropower station, and how to calculate the benefits of hydropower stations suitable for reversible transformation in the region to the regional power grid after transformation. Therefore, in response to the above problems, it is necessary to establish a regional planning analysis method with reversible transformation of hydropower. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a regional planning analysis method with reversible transformation of hydropower, which can use the planning method to propose specific transformation plans, including hydropower stations undergoing reversible transformation and the installed capacity of newly added reversible units after the transformation.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing a regional planning analysis method with reversible hydropower transformation, comprising the following steps:

[0005] S1. Preliminary screening of hydropower stations in the region: Screen the hydropower stations in the analysis area and remove those that are not suitable for reversible transformation;

[0006] S2. Establishment of planning model: The planning model is optimized by minimizing the total cost of the power system;

[0007] S3. Model solution and result analysis: Input relevant parameters and data of various units.

[0008] According to the above scheme, in step S1, the screening method adopted is: based on the two parameters of distance-to-height ratio L / H and the horizontal distance L from the downstream hydropower station reservoir, the hydropower stations with a distance-to-height ratio <50 and a horizontal distance <10 km are retained.

[0009] According to the above scheme, in step S2, the total cost part includes the investment cost of reversible hydropower stations, the investment cost of new thermal power units and new energy units, operating costs, fixed operation and maintenance costs, and investment and operation and maintenance costs of energy storage units; the constraints of the model include relevant constraints on various types of units such as wind, solar, water and fire, relevant constraints on reversible units, system power balance constraints and system standby constraints.

[0010] According to the above scheme, in step S3, the relevant parameters and data of various units are input, including the important parameters of the standard water head H and horizontal distance L of the hydropower station screened in step S1, and the planning model solving software is used to solve and perform relevant analysis.

[0011] According to the above scheme, in step S1, the evaluation method of the rated water head H and the horizontal distance L is as follows:

[0012]

[0013]

[0014]

[0015] Where K is the drawdown depth coefficient, and 0.5 is taken as a typical value in the calculation. tmax is the maximum water head, H tmin is the minimum water head; The normal water level of the upper reservoir. is the dead water level of the upper reservoir, The normal water level of the lower reservoir. It is the dead water level of the lower reservoir;

[0016] The horizontal distance is estimated as follows:

[0017]

[0018] In the formula, is the height of the lower reservoir dam, L R is the length of the river.

[0019] According to the above scheme, in step S2, the capacity of the reversible hydroelectric unit and the operation decision variables of the reversible hydroelectric unit are increased.

[0020] According to the above scheme, in step S2, the investment cost of the reversible hydroelectric generator set and the operation and maintenance cost of the reversible hydroelectric generator set are increased;

[0021] The total cost of reversible hydropower transformation is expressed as a linear function of the installed capacity of the newly added reversible units. The total investment cost of the reversible hydropower station is As shown below:

[0022]

[0023] Where N p is the number of provinces in the planning area, M is the number of cascade hydropower units that can be transformed in province k, is the capacity of the reversible unit expected to be installed in the future in the planning model, that is, the decision variable in the planning model, which is generally used as the upper limit of the installed reversible unit power generation and pumping power. H and L are the rated head and horizontal distance of the inlet and outlet of the reversible hydropower station, respectively. The H and L parameters are determined according to the actual environment of the transformation. and They are functions related to H and L, i.e., the actual environment of the reservoir, respectively, and are determined parameters when the reversible transformation site is determined;

[0024] The planning model considers the planning results of a certain year or several years. If it is considered in terms of total investment cost, it is obviously unreasonable to directly add the total investment cost into the objective function. Therefore, the concept of annualized investment cost is introduced using the capital recovery coefficient, taking into account the interest rate and the operating life of the reversible unit:

[0025]

[0026]

[0027] Where i is the interest rate, T is the life of the newly built reversible unit, CRF is the capital recovery factor, is the annualized investment cost of adding a new reversible unit.

[0028] Operation and maintenance costs of reversible hydropower units To fix the operation and maintenance cost, a certain proportion of the total investment cost of the reversible hydropower unit is considered, as shown in the following formula:

[0029]

[0030] Among them, ε is the proportionality coefficient, which is generally between 2.5% and 3%.

[0031] According to the above scheme, in step S2, the modeling and related constraints of the reversible hydroelectric unit are added;

[0032] The modeling of reversible units is similar to that of pumped storage units. Both are divided into two conditions for analysis: pumping conditions and power generation conditions. The unit modeling can be described in detail as follows:

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041] in, are the pumped power generation power of the reversible unit x of the hydropower station i at time t, are the pumping power generation flow of the reversible unit x of hydropower station i at time t, are the net water head of the reservoir of the reversible unit x of the hydropower station i under the pumping power generation condition at time t, η pump η gen are the efficiencies of the reversible unit under pumped power generation conditions, and are the upper / lower reserve capacity of the reversible unit under pumped power generation conditions, It is the head loss during pumping (power generation);

[0042] Other operating constraints of reversible hydroelectric units can be described as:

[0043]

[0044]

[0045]

[0046]

[0047]

[0048] Among them, the first two constraints are the output limit constraints of the reversible unit under different working conditions. are the maximum and minimum outputs of the reversible unit x of the hydropower station i under pumping conditions, are the maximum and minimum outputs of the reversible unit x of the hydropower station i under power generation conditions, A 0-1 variable indicating the working state of the unit. When the reversible unit x of the hydropower station i is in the pumping condition at time t is 1, when the reversible unit x of the hydropower station i is in the power generation state at time t is 1, are the upper and lower limits of the net water head of the reversible unit x of the hydropower station i under the pumping condition, They are the upper and lower limits of the net water head of the reversible unit x of the hydropower station i under power generation conditions;

[0049] The relationship between net head, storage capacity and flow is established by combining the water level-reservoir capacity curve with the flow balance constraint and the water volume balance constraint. Compared with the water volume balance constraint in cascade hydropower, the specific description is as follows:

[0050]

[0051]

[0052] V min ≤V i,t ≤V max

[0053]

[0055] The first constraint represents the functional relationship obtained from the water level storage capacity curve, and the second equation represents the average of the storage capacity at this moment and the storage capacity at the next moment as the input of the functional relationship. max V min They represent the upper and lower limits of the reservoir capacity of hydropower station i respectively. The fourth constraint on flow indicates that the total flow of hydropower station i at time t includes the power generation flow of the hydropower station at this time. Amount of water discarded Power generation flow of reversible units and pumping flow and the flow rate that serves as the unit's spare capacity The last constraint involving reservoir capacity is the water balance constraint. represents the natural water inflow at time t, Δt is the time interval, which is equivalent to the simulation step size; τ is the upstream and downstream water flow lag, which represents the time required for the upstream discharge to reach the downstream reservoir.

[0056] The regional planning analysis method with reversible hydropower transformation of the present invention has the following beneficial effects:

[0057] The present invention provides a way to obtain a reversible transformation plan for regional hydropower. By using this analysis method, by inputting relevant parameters of various units and standard head and horizontal distance parameters required for reversible transformation, a plan for reversible transformation of hydropower stations in the region can be obtained, and at the same time, a new construction plan for thermal power, wind and solar power and energy storage units in the region after reversible transformation, the optimal investment cost and hourly scheduling of the power system can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0059] Figure 1 It is a planning model framework diagram of the regional planning analysis method with reversible hydropower transformation of the present invention;

[0060] Figure 2 It is an evaluation method of the horizontal distance L of the regional planning analysis method with hydropower reversible transformation of the present invention;

[0061] Figure 3 It is a typical weekly load balance diagram of the central China region in 2030 after the transformation in the embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0063] like Figure 1 As shown, the regional planning analysis method with hydropower reversible transformation of the present invention comprises the following steps:

[0064] S1. Preliminary screening of hydropower stations in the region:

[0065] If reversible unit modeling is performed for each hydropower station in the analyzed area, the computational burden of the model will be greatly increased, and not all hydropower stations are suitable for reversible transformation. Therefore, it is necessary to screen the hydropower stations in advance and remove the obviously unsuitable ones. The screening method is mainly based on the two parameters of the distance-to-height ratio (L / H) and the horizontal distance L from the reservoir of the downstream hydropower station, and only the hydropower stations with a distance-to-height ratio <50 and a horizontal distance <10km are retained.

[0066] The evaluation method of rated head H is as follows:

[0067]

[0068]

[0069]

[0070] Where K is the drawdown depth coefficient, which can be taken as 0.5 as a typical value in calculation, and H tmax is the maximum water head, H tmin is the minimum water head. The normal water level of the upper reservoir. is the dead water level of the upper reservoir, The normal water level of the lower reservoir. It is the dead water level of the lower reservoir.

[0071] The horizontal distance L is evaluated as follows: Figure 2As shown in the figure, it can be seen that when the parameters such as river channel length, lower reservoir dam height, and lower reservoir water level are known, the horizontal distance can be estimated as follows:

[0072]

[0073] In the formula, is the height of the lower reservoir dam, L R is the length of the river.

[0074] S2. Establishment of planning model:

[0075] In terms of the decision variable setting of the model, according to the actual situation of the study area, it generally includes two types of decision variables, namely capacity addition decision variables and operation decision variables.

[0076] The expansion decision variables include the installed capacity of thermal power units, reversible hydropower units, wind power and solar photovoltaic power generation in each province in the planning area in the target year. represents the newly installed capacity of the i-th category of thermal power units in province k, and defines and The newly built reversible hydropower, wind power and photovoltaic power generation capacity in province k. For the energy storage system, two dimensions of cost are considered for each energy storage system: the cost related to the total energy storage capacity ($ / kWh) and the cost of the maximum charging and discharging power ($ / kW). and The maximum charging, discharging and energy storage capacity of the newly added energy storage system category z in province k.

[0077] The operation decision variables are analyzed for different units. For the operation of a single thermal power unit, the operation status of each independent unit at each time interval should be determined. The operation status of each unit is represented by three binary variables: and represents the online / offline status, startup and shutdown behavior of unit i at time t, and is combined with the rated capacity to simulate the operation of a single unit i. In order to speed up the calculation and reduce the computational complexity, we use unit grouping technology and re-model the operation simulation of thermal power units through the latest fast unit combination model. After unit grouping and aggregation, thermal power units with similar operating characteristics in each province can be re-represented by three integer variables. and They represent the online capacity, startup capacity and shutdown capacity of unit c at time t. As the scale of the power system increases, the three integer variables are further relaxed into continuous variables and the operation of thermal power units is remodeled accordingly. and It represents the total online capacity, total startup and shutdown capacity of the i-th type thermal power unit in the k-th province at time t. At time t, the total output power of the i-th type thermal power unit in the k-th province is constrained by the following formula:

[0078]

[0079] in, and The annual installed capacity of the i-th type of thermal power unit in province k and the cumulative installed capacity in the planning year are defined. The flexibility modeling using the above continuous variables is then presented in Section 3.2.

[0080] For wind power and solar photovoltaic power generation, the model includes the hourly power output and installed capacity of each type of renewable energy. and They represent the total power output of wind power and photovoltaic power generation at time t in province k:

[0081]

[0082] in, and Represents the current grid-connected scale of wind power and solar photovoltaic power generation in the kth province. and represents the total installed capacity of wind power and photovoltaic power generation in the kth province during the planning period. The hourly capacity factor describing the physical fluctuation characteristics of renewable power output is represented by α t,k ,β t,k express.

[0083] For the operation of hydropower units, and They represent the hourly power generation, reserve capacity and overflow of the i-th hydropower unit in the planning area at time t. For the operation of reversible units, and They represent the hourly power generation, pumping power consumption, generator unit spare capacity and pump unit spare capacity of the i-th hydropower unit that has completed reversible transformation in the planning area at time t. For run-of-river hydropower stations, and represents the hourly power generation and reserves of all runoff hydropower units in province k at time t.

[0084] The objective function of the model is to minimize the total cost of the power system, the cost part of which includes the investment cost of the reversible hydropower station. Fixed operation and maintenance costs of reversible hydropower plants Investment costs of new thermal power units and new energy units Running costs Fixed Operation and Maintenance (O&M) Costs Investment and operation and maintenance costs of energy storage units Ces .

[0085] The objective function of the model can be expressed as:

[0086]

[0087] Total investment cost of reversible hydropower station Including hub engineering cost C HP , independent cost C IF and basic preparation cost C PH The cost of the hub project accounts for more than 80% of the static investment of the project. At the same time, the independent cost can be expressed as a linear function of the hub project cost, and the basic preparatory cost can be expressed as a certain proportion of the independent cost and the hub project cost. Therefore, the total investment cost of the reversible hydropower station is It can be expressed as the hub project cost C HP The linear function of is derived as follows:

[0088] C IF =α IF ·C HP +β IF

[0089] C PH =α PH ·(C HP +C IF )=α PH ·(1+α IF )·C HP +α PH β IF

[0090] C SI =C HP +C IF +C PH =(1+α IF +α PH ·(1+α IF ))·C HP +(1+α PH )·β IF

[0091] Therefore, in order to obtain the functional relationship between the investment cost of reversible hydropower transformation and the newly added capacity of reversible units in hydropower station transformation, it is only necessary to obtain the functional relationship between the hub project cost and the newly added capacity of reversible units in hydropower station transformation. HP Divided into electrical equipment cost C E , pump turbine cost C PT , water delivery system cost C W , underground plant cost C PS , other construction costs CCA The cost of the water supply system includes several parts: tunnel cost, pipeline cost and other equipment cost, which can be expressed by the following formulas.

[0092]

[0093]

[0094] C W =C T +C P +C ME

[0095]

[0096]

[0097]

[0098]

[0099] C CA =α CA ·N·P+β CA

[0100] In the formula, P represents the capacity of a single unit in MW, N is the number of units, H represents the rated head height in m, and Q represents the maximum flow of a single unit in m. 3 / s. The maximum flow rate of a single unit can be obtained from the output function of the hydropower station, and the capacity conversion efficiency is generally 88%, as shown in the following formula:

[0101]

[0102] Since general planning software cannot solve planning with exponentials, a linear function fitting method in a certain area is used here (for example: P 0.785 ≈0.27P, P∈(0,500)) The above formula is simplified, and the simplified formula results and fitting range are as follows:

[0103]

[0104]

[0105]

[0106] Adding up the final forms, we can get the hub project cost as:

[0107]

[0108] It can be seen that γ(H,L) and χ(H,L) are functions related to the actual environment of the reservoir, respectively. They are fixed parameters when the location of the reversible transformation is determined. Therefore, when the hydropower station in the study area is determined, the cost of the hub project is a linear function of the installed capacity of the newly added reversible unit. Since the total cost of the hydropower reversible transformation is linearly related to the hub project cost, the total cost of the hydropower reversible transformation can be expressed as a linear function of the installed capacity of the newly added reversible unit. The total investment cost of the reversible hydropower station is As shown below:

[0109]

[0110] Where N p is the number of provinces in the planning area, M is the number of cascade hydropower units that can be transformed in province k, It is the capacity of the reversible unit expected to be installed in the future in the planning model, that is, the decision variable in the planning model, which is generally used as the upper limit of the installed reversible unit power generation and pumping power. H and L are the rated head and horizontal distance of the inlet and outlet of the reversible hydropower station, respectively. Parameters such as H and L can be determined according to the actual environment of the transformation. and They are functions related to H and L, that is, the actual environment of the reservoir, respectively, and are determined parameters when the location of the reversible transformation is determined.

[0111] Since the planning model considers the planning results of a certain year or several years, it is obviously unreasonable to consider it according to the total investment cost, that is, directly adding the total investment cost into the objective function. Therefore, the concept of annualized investment cost is introduced using the capital recovery coefficient, taking into account the interest rate and the operating life of the reversible unit.

[0112]

[0113]

[0114] Where i is the interest rate, T is the life of the newly built reversible unit, CRF is the capital recovery factor, is the annualized investment cost of adding a new reversible unit.

[0115] Operation and maintenance costs of reversible hydropower units Mainly fixed operation and maintenance costs, which can be considered as a certain proportion of the total investment cost of the reversible hydropower unit, as shown in the following formula:

[0116]

[0117] Among them, ε is the proportionality coefficient, which is generally between 2.5% and 3%.

[0118] New investment costs for thermal power and new energy units It can be expressed by the following formula:

[0119]

[0120] Investment cost is the total annualized investment cost of new installed capacity between the year in our system model and the specific study year, including thermal power units, wind power, and solar photovoltaic power generation; for the investment cost shown in the above formula and Represents the annualized capital cost per unit capacity of thermal power units, wind power, and solar power generation facilities in province k ($ / kW).

[0121] Running costs That is, the total operating cost of all units in the planning area, including the fuel cost of thermal power units, the operating costs of hydropower stations and thermal power stations, and the start-up and shutdown costs of various types of thermal power units, which can be expressed as follows:

[0122]

[0123] At every hour of the year. It is the operating cost of a thermal power unit per kilowatt-hour. Represents the startup / shutdown cost per kilowatt of thermal power units.

[0124] Fixed operation and maintenance costs It covers all types of power generation technologies in the planning area and is calculated based on the corresponding operation and maintenance proportionality factor, which is defined as the ratio of the annual O&M cost of a specific power generation technology to the total investment cost.

[0125]

[0126] In the above formula, represents the annual operation and maintenance cost per kilowatt of the i-th type thermal power unit in province k. Similarly, represents the fixed O&M cost per kW for other types of power generation infrastructure, e.g., x=w for wind power and x=s for solar PV. It represents the total installed capacity of hydropower units in province k in the planning year.

[0127] The total cost of the energy storage system includes amortized investment and operating costs, and the formula is as follows:

[0128]

[0129] In the above formula, N es For the energy storage unit category, please note that the power ratio cost Related to the cost of rotating synchronous machines in pumped storage units or power electronic rectifiers / inverters in battery storage systems, or to the cost of anodes and cathodes in flow batteries. Related to the cost of the reservoir in a pumped storage system or a solution including flow batteries. It is proportional to the charge and discharge power. represents the discharge power of the energy storage unit of type z in province k at time t, It represents the charging power of the energy storage unit of type z in province k at time t.

[0130] The constraints of the model include various unit constraints and system constraints.

[0131] Reversible hydropower stations include two types of units: hydropower units and reversible units. They can generate electricity like cascade hydropower stations and pump water like pumped-storage power stations. The following will conduct modeling and analysis around hydropower units, reversible units and reservoirs.

[0132] Compared with the traditional hydropower model, the hydropower unit modeling takes into account the influence of the hydropower unit vibration area, and analyzes in detail the relationship between the water head and the power generation flow and the flood discharge flow. The unit modeling can be described in detail as follows:

[0133]

[0134]

[0135]

[0136]

[0137]

[0138] in, is the power generation of unit x of hydropower station i at time t, ρ is the density of water, g is the acceleration of gravity, η hydro For hydropower generation efficiency, is the power generation flow of the x-unit of the hydropower station i, The net water head of the reservoir of the hydropower station i, are the upper and lower spare capacities of the x-unit of hydropower station i, are the upper reservoir head, lower reservoir head and head loss, is the amount of water abandoned by hydropower station i at time t, and the last constraint is the tailwater-discharge flow curve.

[0139] The operating constraints of the hydropower unit can be described in detail as follows:

[0140]

[0141]

[0142]

[0143]

[0144]

[0145] in, They are the upper and lower limits of the output in the upper vibration area of ​​the hydropower unit, They are the upper and lower limits of the output in the lower vibration area of ​​the hydropower unit, To determine the working area of ​​the hydropower unit 0-1 variable, when working in the upper vibration area, then is 1, when working in the lower vibration area, At the same time, among the five operating constraints above, the second constraint on two 0-1 variables ensures that the hydropower unit can only work in one area at the same time, the third constraint is the limit on the amount of abandoned water, and the fourth constraint represents the water level-flood discharge capacity curve of the hydropower unit. min,i,x H max,i,x They are the upper and lower limits of the net water head of the hydropower station reservoir respectively.

[0146] The modeling of reversible units is similar to that of pumped storage units. Both are divided into two conditions for analysis: pumping conditions and power generation conditions. The unit modeling can be described in detail as follows:

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] in, are the pumping (generating) power of the reversible unit x of the hydropower station i at time t, are the pumping (power generation) flow of the reversible unit x of the hydropower station i at time t, are the net water head of the reservoir of the reversible unit x of the hydropower station i under the pumping (generating) condition at time t, ηpump η gen are the efficiencies of the reversible unit under pumping (power generation) conditions, and They are the upper (lower) reserve capacity of the reversible unit under pumping (power generation) conditions, It is the head loss during pumping (power generation).

[0156] Other operating constraints of reversible hydroelectric units can be described as:

[0157]

[0158]

[0159]

[0160]

[0161]

[0162] Among them, the first two constraints are the output limit constraints of the reversible unit under different working conditions. are the maximum and minimum outputs of the reversible unit x of the hydropower station i under pumping conditions, are the maximum and minimum outputs of the reversible unit x of the hydropower station i under power generation conditions, A 0-1 variable indicating the working state of the unit. When the reversible unit x of the hydropower station i is in the pumping condition at time t is 1, when the reversible unit x of the hydropower station i is in the power generation state at time t is 1, are the upper and lower limits of the net water head of the reversible unit x of the hydropower station i under the pumping condition, They are the upper and lower limits of the net water head of the reversible unit x of hydropower station i under power generation conditions.

[0163] The relationship between net head, storage capacity and flow is established by combining the water level-storage capacity curve with the flow balance constraint and water volume balance constraint. The specific description is as follows:

[0164]

[0165]

[0166] V min ≤V i,t ≤V max

[0167]

[0168] The first constraint represents the functional relationship obtained from the water level storage capacity curve, and the second equation represents the average of the storage capacity at this moment and the storage capacity at the next moment as the input of the functional relationship. max V min They represent the upper and lower limits of the reservoir capacity of hydropower station i respectively. The fourth constraint on flow indicates that the total flow of hydropower station i at time t includes the power generation flow of the hydropower station at this time. Amount of water discarded Power generation flow of reversible units and pumping flow and the flow rate that serves as the unit's spare capacity The last constraint involving reservoir capacity is the water balance constraint. represents the natural water flow at time t, Δt is the time interval, which is equivalent to the simulation step size. τ is the upstream and downstream water flow lag, which represents the time required for the upstream discharge to reach the downstream reservoir.

[0170] The modeling of cascade hydropower units is the same as that of hydropower units in reversible hydropower stations. Relevant constraints including water balance constraints are also given in the modeling section of reversible hydropower stations and will not be repeated here.

[0171] Run-of-river hydropower stations are a general term for unregulated hydropower stations that have no ability to regulate natural runoff and hydropower stations that can only perform daily regulation. Since run-of-river hydropower stations are not affected by reservoir regulation, hourly scheduling is not constrained by cascade effects. For the operation simulation of run-of-river hydropower stations, the two decision variables of the total output of run-of-river hydropower and the spinning reserve that run-of-river hydropower can provide are mainly considered, namely:

[0172]

[0173]

[0174] In the formula, represents the total output of run-of-river hydropower in region k during period t; represents the spinning reserve provided by run-of-river hydropower in region k during period t; is the total installed capacity of run-of-river hydropower units in region k; It represents the output coefficient of the run-of-river hydropower station based on historical data of previous years, which is equal to the ratio of the historical total output of the run-of-river hydropower station to the rated total installed capacity at time period t.

[0175] In terms of thermal power units, when conducting hourly simulation operations throughout the year, the number of units in the model is large, the time scale is large, and the number of decision variables can reach hundreds of millions. If the traditional unit combination model is still used, it is difficult to obtain the optimal solution to the model due to the insufficient processing capabilities of existing mathematical solution technologies for optimization problems involving a large number of integer variables. Therefore, a fast unit combination algorithm is introduced.

[0176] First, the thermal power units with the same or similar power generation capacity and operating parameters in the same partition subsystem are aggregated into a cluster thermal power unit. For cluster thermal power unit j, the startup capacity is introduced. and startup capacity and downtime capacity Variable. The operating capacity of the cluster thermal power unit j at time t is defined as the sum of the rated capacities of all units in grid-connected operation at time t, and the starting capacity It is defined as the sum of the rated capacities of all the units that have just started and connected to the grid at time t, and the shutdown capacity It is defined as the sum of the rated capacities of all units to be shut down at time t. Since the change in the start-up and shutdown status of the units will directly affect the change in the overall startup capacity of the cluster units, if the operating status of each unit is not considered, the startup capacity of the total capacity of cluster thermal power unit j at time t can be directly regarded as a decision variable. In this method, a continuous variable is introduced to describe the startup capacity in the total capacity of the cluster thermal power unit to approximately characterize the operating status of the cluster thermal power unit. The value range of the continuous variable describing the operating status of the cluster thermal power unit is:

[0177]

[0178] Among them, the total capacity of cluster thermal power units is S j The sum of the rated capacities of all units Indicates the rated capacity of unit i.

[0179] The change of the startup capacity of cluster thermal power unit j between adjacent moments can be expressed as:

[0180]

[0181] The output power p of unit i at time t i (t) Satisfy the operating range constraints:

[0182]

[0183] In the formula, the operating parameters and Alpha j (t) represent the minimum and maximum technical output levels of cluster thermal power unit j, respectively, and the minimum and maximum technical output levels of unit i are α i (t) The weighted average is obtained, and the weight is the rated capacity of unit i Total capacity S j The calculation formula is as follows:

[0184]

[0185]

[0186] in, and Respectively indicate the boot capacity The corresponding minimum and maximum output power. When it is zero, it means that no unit in the cluster thermal power unit j is connected to the grid and the corresponding output power is zero.

[0187] The up-climbing and down-climbing constraints of cluster unit output power:

[0188]

[0189]

[0190] In the uphill climbing constraint, It represents the startup capacity that can provide power ramp-up capability from time t-1 to time t, and the corresponding maximum ramp-up power is parameter is the ramp rate of cluster unit j, which indicates the ratio of the maximum ramp capacity to the total capacity in the unit calculation period, which is calculated by the maximum ramp rate of each unit. Calculated according to the weighted average of rated capacity, that is:

[0191]

[0192] In the downhill climbing constraint, It represents the startup capacity that can provide power ramp-down capability from time t-1 to time t, and the corresponding maximum ramp-down power is parameter is the ramp-down rate of cluster unit j, which indicates the ratio of the maximum ramp-down capacity to the total capacity in the unit calculation period. Calculated according to the weighted average of rated capacity, that is:

[0193]

[0194] Considering the startup power climbing constraint, shutdown power climbing constraint and maximum up and down climbing capabilities, the output power of cluster unit j at time t also needs to meet the following requirements:

[0195]

[0196] Assume that the minimum startup operation time of all units in cluster unit j is The same, then the minimum startup time of cluster unit j is equal The minimum startup time constraint of cluster units can be described as:

[0197]

[0198]

[0199]

[0200] Assume that the minimum number of downtime hours for all units in cluster unit j is The same, then the minimum downtime of cluster unit j equal The minimum offline time constraint of the cluster unit can be described as:

[0201]

[0202]

[0203]

[0204] Regarding the energy storage unit, under the operating constraints, the upper and lower limits of the hourly charging and discharging power and newly installed capacity of the energy storage system are:

[0205]

[0206]

[0207]

[0208] The energy balance of the energy storage system is shown below:

[0209]

[0210] in and The charging and discharging efficiency and energy loss rate (self-discharge) of the z-th energy storage system are defined. The energy level is limited by the installed capacity:

[0211]

[0212] in and are the lower and upper bounds of the remaining energy in the energy storage system in k provinces, respectively. In the actual optimization, we assume that the energy level of the energy storage in the first time interval is equal to the energy level in the last time interval.

[0213] The energy storage system can also provide backup for the operation of the power system. The backup is determined by the following three formulas:

[0214]

[0215]

[0216]

[0217] The spinning reserve provided by the energy storage system is limited by the total rated discharge power and the surplus energy. In addition, the maximum number of ampere-hours or watt-hours (Wh) that the battery can pass during its service life is usually provided by the battery manufacturer. This constraint is expressed on a yearly basis:

[0218]

[0219] in, is the annualized watt-hour throughput of the z-th type of energy storage system.

[0220] The system power balance constraint is described as:

[0221]

[0222] Among them, P j (t) is the output power of the jth cluster unit in regional power grid k at time t, is the power generation of renewable energy, hydropower and nuclear power in regional power grid k at time t, L k (t) is the load power of regional power grid k at time t, is the inter-regional power exchange between regional grid k and regional grid m, and are the generating power and pumping power of the pumped storage unit in regional power grid k at time t. The direction of is defined as: when the power transmitted by regional grid k to regional grid m, is a positive value; when regional grid k receives power from regional grid m, is a negative value. k All other regional power grids connected to regional power grid k through inter-regional interconnection lines are defined.

[0223]

[0224] The left side of the above formula represents the maximum power that each power source in the regional power grid k can output at time t, where is the startup capacity of the jth cluster unit in regional power grid k at time t, is the maximum power that can be generated by renewable energy in regional power grid k. The right side of the reserve formula represents the load power, inter-regional interconnection line power exchange and spinning reserve demand R of regional power grid k. k (t). The spinning reserve demand R of regional power grid k at time t k (t) Determined by load power and maximum output of new energy:

[0225]

[0226] parameter and They represent the load power and the reserve demand coefficient of the maximum output power of new energy. Corresponding to the prediction error of renewable energy output, it takes into account the impact of the uncertainty of renewable energy output on system operation.

[0227] S3. Model solution and result analysis: Input the relevant parameters and data of various units, including the important parameters of the hydropower station selected in step S1 (standard head H, horizontal distance L), and use the planning model solution software to solve and perform relevant analysis.

[0228] Example

[0229] The regional planning analysis method with reversible transformation of hydropower is carried out by taking the central China region as an example, including the following steps:

[0230] S1. Preliminary screening of hydropower stations in the region

[0231] After screening the hydropower stations in the central China region, thirteen hydropower stations suitable for reversible hydropower transformation were obtained in the following basins. The following Table 1 uses the screening results as a basis for the next step of simulation analysis and calculation.

[0232] Table 1 Thirteen hydropower stations suitable for reversible hydropower transformation

[0233]

[0234] S2. Establishment of planning model

[0235] According to the actual situation in the central China region, the relevant decision variables and objective function composition of the model are determined. The optimization is carried out by minimizing the total cost of the power system. The cost part includes the investment cost of reversible hydropower stations, the investment cost of new thermal power units and new energy units, operating costs, fixed operation and maintenance costs, investment and operation and maintenance costs of energy storage units, etc.; the constraints of the model mainly include the relevant constraints of various units (wind, solar, water and fire), the relevant constraints of reversible units, system power balance constraints and system standby constraints.

[0236] S3. Model solution and result analysis

[0237] Use MATLAB and YALMIP to write a program according to the objective function and model constraints. Figure 1 The input information in the model framework diagram is input and solved using the gurobi commercial solver. The model solution time is 9892.3s.

[0238] According to the simulation results, the following analysis is given.

[0239] Table 2 Planned additional installed capacity of reversible units in Central China by 2030

[0240]

[0241] The planning analysis shows that the maximum benefit can be obtained by carrying out reversible transformation of the corresponding capacity in the above hydropower station. It can be seen from Tables 3 and 4 that the newly added thermal power installed capacity in 2030 is reduced before and after the transformation, while reducing the thermal power output, thereby reducing the cost of thermal power operation, and ultimately reducing the total annual operating cost of the entire region. In addition, it can also be seen that the installation of reversible units also reduces the output of energy storage units, because the operation and maintenance costs of reversible hydropower units are lower than those of energy storage units. Although the investment and operation and maintenance of reversible unit transformation are also a considerable expense, compared with the benefits brought, the cost increase brought by the transformation investment is acceptable.

[0242] Table 3 Analysis of the total annual cost of the power grid in Central China in 2030 before and after the transformation

[0243]

[0244]

[0245] Table 4 Analysis of the total annual power generation of the Central China regional power grid in 2030 before and after the transformation

[0246]

[0247] At the same time, it can be seen from Table 4 that the installation of reversible units can also increase the absorption capacity of wind and solar units to a certain extent. In order to better see the absorption effect of reversible transformation on the new energy units in the region, the wind and solar abandonment rates in 2030 before and after the transformation of the four provinces in central China were compared and analyzed. It can be seen from Table 5 that after the transformation, the absorption situation in the central China provinces has been significantly improved.

[0248] Table 5 Analysis of power abandonment rate in four provinces in central China in 2030 before and after transformation

[0249] Central China Hubei Hunan Henan Jiangxi Abandoned light before transformation 4.31％ 4.49％ 5.56％ 6.48％ 9.63％ Abandoned light after transformation 2.18％ 2.35％ 3.05％ 3.16％ 5.64％ Wind curtailment before transformation 2.74％ 4.07％ 3.12％ 3.54％ 4.59％ Wind power abandoned after transformation 1.72％ 2.33％ 1.86％ 2.74％ 3.00％

[0250] Finally, according to Figure 3From the typical weekly load balance after the transformation, it can be seen that power abandonment mostly occurs when the photovoltaic output is the largest, that is, at noon. The reversible unit is generally in the pumping condition at noon, storing the excess electricity generated by the wind and solar units in the form of potential energy, and when the reversible unit is in the power generation condition, the general power generation output trend is the same as the overall hydropower output trend in central China. This helps to reduce the peak load regulation pressure of the power grid during the noon peak period and promote the consumption of renewable energy, which also confirms the relevant conclusions of Tables 3 and 4.

[0251] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A regional planning analysis method with reversible hydropower transformation, characterized in that: The following steps are involved: S1. Screen the hydropower stations in the analysis area and remove those that are not suitable for reversible transformation; S2, the planning model optimizes by minimizing the total cost of the power system; S3. Input the relevant parameters and data of various units, and use the planning model to solve and analyze.

2. The regional planning analysis method with reversible hydropower transformation according to claim 1 is characterized in that: In step S1, the screening method adopted is: based on two parameters, the distance-to-height ratio L / H and the horizontal distance L from the reservoir of the downstream hydropower station, the hydropower stations with a distance-to-height ratio <50 and a horizontal distance <10 km are retained.

3. The regional planning analysis method with reversible hydropower transformation according to claim 1 is characterized in that: In step S2, the total cost part includes the investment cost of reversible hydropower stations, the investment cost of new thermal power units and new energy units, operating costs, fixed operation and maintenance costs, and investment and operation and maintenance costs of energy storage units; the constraints of the model include relevant constraints on various types of units such as wind, solar, water and fire, relevant constraints on reversible units, system power balance constraints and system standby constraints.

4. The regional planning analysis method with reversible hydropower transformation according to claim 1 is characterized in that: In step S3, relevant parameters and data of various units are input, including important parameters of the standard water head H and horizontal distance L of the hydropower station selected in step S1, and the planning model solving software is used to solve and perform relevant analysis.

5. The regional planning analysis method with reversible hydropower transformation according to claim 2 is characterized in that: In step S1, the evaluation method of the rated water head H and the horizontal distance L is as follows: Where K is the drawdown depth coefficient, and 0.5 is taken as a typical value in the calculation. tmax is the maximum water head, H tmin is the minimum water head; The normal water level of the upper reservoir. is the dead water level of the upper reservoir, The normal water level of the lower reservoir. It is the dead water level of the lower reservoir; The horizontal distance is estimated as follows: In the formula, is the height of the lower reservoir dam, L R is the length of the river.

6. The regional planning analysis method with reversible hydropower transformation according to claim 3 is characterized in that: In the step S2, the capacity of the reversible hydroelectric unit and the operation decision variables of the reversible hydroelectric unit are added.

7. The regional planning analysis method with reversible hydropower transformation according to claim 6 is characterized in that: In the step S2, the investment cost of the reversible hydroelectric generator set and the operation and maintenance cost of the reversible hydroelectric generator set are increased; The total cost of reversible hydropower transformation is expressed as a linear function of the installed capacity of the newly added reversible units. The total investment cost of the reversible hydropower station is As shown below: Where N p is the number of provinces in the planning area, M is the number of cascade hydropower units that can be transformed in province k, is the capacity of the reversible unit expected to be installed in the future in the planning model, that is, the decision variable in the planning model, as the upper limit of the installed reversible unit power generation and pumping power, H and L are the rated head and horizontal distance of the inlet and outlet of the reversible hydropower station, respectively, and the H and L parameters are determined according to the actual environment of the transformation. and They are functions related to H and L, that is, the actual environment of the reservoir, respectively, and are determined parameters when the reversible transformation site is determined; The planning model considers the planning results for a certain year or several years, uses the capital recovery factor to introduce the concept of annualized investment cost, and considers the interest rate and the operating life of the reversible unit: Where i is the interest rate, T is the life of the newly built reversible unit, CRF is the capital recovery factor, is the annualized investment cost of adding a new reversible unit. Operation and maintenance costs of reversible hydropower units To fix the operation and maintenance cost, a certain proportion of the total investment cost of the reversible hydropower unit is considered, as shown in the following formula: Among them, ε is the proportionality coefficient, which is generally between 2.5% and 3%.

8. The method for regional planning analysis with reversible hydropower transformation according to claim 7, characterized in that: In the step S2, the modeling and related constraints of the reversible hydroelectric unit are added; The modeling of reversible units is similar to that of pumped storage units. Both are divided into two conditions for analysis: pumping conditions and power generation conditions. The unit modeling can be described in detail as follows: in, are the pumped power generation power of the reversible unit x of the hydropower station i at time t, are the pumping power generation flow of the reversible unit x of hydropower station i at time t, are the net water head of the reservoir of the reversible unit x of the hydropower station i under the pumping power generation condition at time t, η pump η gen are the efficiencies of the reversible unit under pumped power generation conditions, and are the upper / lower reserve capacity of the reversible unit under pumped power generation conditions, It is the head loss when pumping water for power generation; Other operating constraints of reversible hydroelectric units can be described as: Among them, the first two constraints are the output limit constraints of the reversible unit under different working conditions. are the maximum and minimum outputs of the reversible unit x of the hydropower station i under pumping conditions, are the maximum and minimum outputs of the reversible unit x of the hydropower station i under power generation conditions, A 0-1 variable indicating the working state of the unit. When the reversible unit x of the hydropower station i is in the pumping condition at time t is 1, when the reversible unit x of the hydropower station i is in the power generation state at time t is 1, are the upper and lower limits of the net water head of the reversible unit x of the hydropower station i under the pumping condition, They are the upper and lower limits of the net water head of the reversible unit x of the hydropower station i under power generation conditions; The relationship between net head, storage capacity and flow is established by combining the water level-reservoir capacity curve with the flow balance constraint and the water volume balance constraint. Compared with the water volume balance constraint in cascade hydropower, the specific description is as follows: The first constraint represents the functional relationship obtained from the water level storage capacity curve, and the second equation represents the average of the storage capacity at this moment and the storage capacity at the next moment as the input of the functional relationship. max V min They represent the upper and lower limits of the reservoir capacity of hydropower station i respectively. The fourth constraint on flow indicates that the total flow of hydropower station i at time t includes the power generation flow of the hydropower station at this time. Amount of water discarded Power generation flow of reversible units and pumping flow and the flow rate that serves as the unit's spare capacity The last constraint involving reservoir capacity is the water balance constraint. represents the natural water inflow at time t, Δt is the time interval, which is equivalent to the simulation step size; τ is the upstream and downstream water flow lag, which represents the time required for the upstream discharge to reach the downstream reservoir.

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