Self-adaptive optimization method for spinning reserve load oriented to economic operation of hydropower station

Abstract

The present application relates to the technical field of hydropower station operation control, in particular to a rotating reserve load adaptive optimization method for economic operation of a hydropower station, comprising the following steps: obtaining reservoir, power grid and unit data, determining target discharge and initial water head, setting rotating reserve load candidate values, calculating rotating reserve flow lower limit and correcting discharge process hour by hour, checking water quantity, water level, unit and reserve constraints, determining rotating reserve load according to minimum water consumption rate, and re-optimizing the remaining dispatching period when data changes. The present application realizes coordination between low load efficiency and upward adjustment space by taking the minimum active power output of the rotating reserve unit as an optimization variable and dynamically converting the rotating reserve flow lower limit in combination with real-time water head; ensures that each candidate scheme compares water consumption rate under the same water consumption boundary by compensating for newly added water across time periods and keeping the total discharge water quantity of the dispatching period unchanged; and avoids unsafe or insufficient reserve schemes by updating water level, water head and operation constraints hour by hour to form a closed loop check.

Description

Technical Field

[0001] This invention relates to the field of hydropower station operation control technology, specifically to an adaptive optimization method for spinning reserve load for the economical operation of hydropower stations. Background Technology

[0002] Hydropower station operation control technology mainly involves adjusting the start-up, shutdown, and active power output of hydropower units based on reservoir water level, inflow, grid load, and unit operating status to meet operational requirements such as grid load supply, spinning reserve, and reservoir water balance. When a hydropower station undertakes spinning reserve tasks, it is necessary to rationally set the minimum spinning reserve output of the operating units to ensure that the units have both appropriate operational stability and regulation capabilities, while also taking into account the economical utilization of hydropower resources.

[0003] During the operation of a hydropower station, reservoir water level, inflow, grid load, unit start-up configuration, and spinning reserve capacity requirements will change. The spinning reserve load needs to adapt to the corresponding operating boundaries. When the minimum spinning reserve output is set too low, the units undertaking the spinning reserve task may operate under low-load and inefficient conditions; when the minimum spinning reserve output is set too high, it may increase the flow through the units and reduce the upward adjustment space of the units. Especially when the target outflow is lower than the lower limit of the spinning reserve flow corresponding to the minimum spinning reserve output, the increased power generation water consumption to meet the minimum spinning reserve output constraint may affect the water balance during the scheduling period and the water level control at the end of the period. Therefore, how to adaptively determine the spinning reserve load with a low power generation water consumption rate according to the hydropower station's operating boundaries while meeting the spinning reserve capacity, water balance, and unit operating constraints is a technical problem that needs to be solved in hydropower stations.

[0004] Therefore, there is an urgent need to develop an adaptive optimization method for the spinning reserve load in order to facilitate the economic operation of hydropower stations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an adaptive optimization method for spinning reserve load for the economical operation of hydropower stations.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides an adaptive optimization method for spinning reserve load for the economical operation of hydropower plants, comprising the following steps:

[0008] S1. Obtain reservoir operation data, power grid dispatch data and unit operation data. Based on these multiple data, determine the target discharge flow rate for each period of the dispatch period and the power generation head for the first period of the dispatch period. Then set multiple candidate values ​​for rotating reserve load. The candidate value for rotating reserve load is the minimum active power output candidate value that each operating unit undertaking the rotating reserve task needs to maintain during the rotating reserve period.

[0009] S2. For each candidate value of rotating reserve load, based on the current generation head and the corresponding relationship between the generator head, active power output and flow rate of the unit, calculate the corresponding lower limit of rotating reserve flow rate for each time period, and adjust the target discharge flow rate of each time period across time periods to obtain the corrected discharge flow rate process. Among them, the corrected discharge flow rate of each time period is not lower than the corresponding lower limit of rotating reserve flow rate and the corrected discharge flow rate during the scheduling period is equal to the target discharge flow rate during the scheduling period.

[0010] S3. Based on the modified discharge flow process, calculate the active power output of the unit, the reservoir water level, the generating head and the upward spinning reserve capacity of the hydropower station corresponding to each spinning reserve load candidate value for each time period, and add the spinning reserve load candidate values ​​that meet the constraints of water balance, end-of-period water level, unit operation and upward spinning reserve capacity to the spinning reserve load feasible candidate set.

[0011] S4. Calculate the power generation water consumption rate based on the total power generation water consumption and total power generation of each rotating reserve load candidate value in the feasible candidate set of rotating reserve loads, and determine the rotating reserve load candidate value with the smallest water consumption rate as the rotating reserve load.

[0012] S5. When the reservoir operation data, power grid dispatch data, or unit operation data change, obtain the updated reservoir operation data, power grid dispatch data, and unit operation data, and redetermine the spinning reserve load for the remaining dispatch period based on the updated data.

[0013] Furthermore, the reservoir operation data includes the current actual water level of the reservoir, the target water level at the end of the scheduling period, the predicted inflow process, the water level-reservoir capacity relationship curve, the downstream water level at the beginning of the scheduling period, and the original time-by-time outflow process; the power grid scheduling data includes the power grid load forecast process, the spinning reserve period, the power grid upward spinning reserve capacity requirement, and the predetermined output shape; the unit operation data includes the unit start-up combination, the unit operating status, the correspondence between head-active power output and through-flow, the unit's minimum feasible output, the unit's maximum available output, the unit's maximum through-flow, and the unit's vibration zone.

[0014] Furthermore, determining the target outflow for each period of the scheduling period and the hydropower head for the first period of the scheduling period includes:

[0015] The initial reservoir capacity and the target reservoir capacity at the end of the scheduling period are calculated based on the current actual water level of the reservoir, the target water level at the end of the scheduling period, and the water level-reservoir capacity relationship curve.

[0016] The target discharge volume for the scheduling period is determined based on the initial reservoir capacity, the target final reservoir capacity, and the predicted inflow process. The target discharge volume for the scheduling period is then allocated to each time period of the scheduling period according to the established power output pattern or the original time-by-time discharge flow process.

[0017] The current actual water level of the reservoir is used as the upstream water level for the first period of the scheduling period. The upstream and downstream water levels for the first period of the scheduling period are calculated to obtain the power generation head for the first period of the scheduling period.

[0018] Furthermore, the step of setting multiple candidate values ​​for spinning reserve load and calculating the corresponding lower limit of spinning reserve flow for each candidate value on a time-period basis includes:

[0019] Multiple candidate values ​​for spinning reserve load are generated within a preset candidate interval according to a preset step size. The same candidate value for spinning reserve load is used by each operating unit undertaking spinning reserve tasks within the same scheduling period.

[0020] According to the time sequence of the scheduling period, based on the current generation head and the correspondence between the head, active power output and flow rate of each operating unit undertaking the spinning reserve task, calculate the lower limit of the unit spinning reserve flow rate of each operating unit undertaking the spinning reserve task under each spinning reserve load candidate value.

[0021] The sum of the lower limits of the spinning standby flow rates of all operating units undertaking spinning standby tasks within the same time period is determined as the lower limit of the spinning standby flow rate for that time period.

[0022] Furthermore, the cross-time adjustment of the target discharge flow for each time period includes:

[0023] When the target discharge flow rate for a certain period is less than the corresponding reserve flow rate lower limit, the corrected discharge flow rate for that period is determined as the reserve flow rate lower limit, and the water volume increased by the corrected discharge flow rate relative to the target discharge flow rate is included in the cumulative water volume to be compensated.

[0024] When the target discharge flow rate in a subsequent period is greater than the corresponding reserve flow rate lower limit, the water volume corresponding to the flow rate difference between the target discharge flow rate and the reserve flow rate lower limit in the subsequent period is taken as the adjustable water volume. The compensation water volume is obtained based on the smaller value between the adjustable water volume and the cumulative water volume to be compensated. The target discharge flow rate in the subsequent period is reduced according to the compensation water volume, and the compensation water volume is deducted from the cumulative water volume to be compensated.

[0025] Furthermore, the step of calculating the unit active power output, reservoir water level, generating head, and hydropower station upward spinning reserve capacity corresponding to each time-period candidate value of spinning reserve load includes:

[0026] The flow rate through each operating unit is adjusted according to the corrected discharge flow rate for each time period. Based on the adjusted flow rate through the unit, the generating head for the corresponding time period, and the correspondence between the unit head, active power output, and flow rate through the unit, the active power output of each operating unit is determined. The sum of the flow rates through each operating unit is the total power generation flow rate of the plant and is equal to the corrected discharge flow rate for the corresponding time period.

[0027] The reservoir capacity is updated based on the predicted inflow and the adjusted total power generation flow of the plant. The reservoir level is determined based on the updated reservoir capacity. The upstream and downstream water levels are calculated to obtain the power generation head for the next period. The lower limit of the reserve flow for the next period is calculated based on the power generation head for the next period.

[0028] Calculate the difference between the maximum available output and the actual active power output of each operating unit undertaking the spinning reserve task at the corresponding generating head, and sum them up to obtain the upward spinning reserve capacity of the hydropower station.

[0029] Candidate values ​​for spinning reserve load that simultaneously meet the following constraints will be added to the feasible candidate set of spinning reserve load: the water level at the end of the scheduling period reaches the target water level at the end of the scheduling period, the water level change on each scheduling day does not exceed the preset daily water level difference limit, the reservoir capacity is within the preset upper and lower limits of the reservoir capacity, the outflow is within the preset outflow range, the active power output of the hydropower station and each operating unit is within the allowable output range, the active power output of each operating unit is not in the unit vibration zone, the active power output of the operating unit undertaking the spinning reserve task is not lower than the candidate value of spinning reserve load, the upward spinning reserve capacity of the hydropower station is not lower than the upward spinning reserve capacity requirement of the power grid, and the cumulative amount of water to be compensated at the end of the scheduling period is zero or within the preset allowable error range of water volume calculation.

[0030] Furthermore, the calculation of the power generation water consumption rate and determination of the spinning reserve load includes:

[0031] The total power generation flow of the plant during each period of the scheduling period is summed up to obtain the total power generation water consumption for each candidate value of spinning reserve load.

[0032] The total power generation of each operating unit during each time period is obtained by summing the product of the active power output of each unit during the scheduling period and the corresponding time period length.

[0033] The power generation water consumption rate is obtained by calculating the ratio of total power generation water consumption to total power generation, and the candidate value of spinning reserve load with the lowest water consumption rate is selected.

[0034] Furthermore, the step of re-determining the spinning reserve load for the remaining scheduling period based on the updated data includes:

[0035] When hydrological forecasts, power grid load predictions, dispatch plans, current actual reservoir water levels, unit start-up combinations, or power grid upward rotation reserve capacity requirements are updated, the actual reservoir water level at the time of the update is recorded as the initial water level for the remaining dispatch period.

[0036] The predicted inflow process, power grid load prediction process, spinning reserve period, unit start-up status and power grid upward spinning reserve capacity requirements after the update time are extracted and together with the initial water level and the target end water level of the remaining scheduling period to form the calculation boundary of the remaining scheduling period.

[0037] Based on the calculation boundary of the remaining dispatch period, a feasible candidate set of spinning reserve load is re-established, the power generation water consumption rate of each spinning reserve load candidate value is calculated, and the spinning reserve load for the remaining dispatch period is determined.

[0038] Furthermore, when there are multiple periods within the same scheduling day where the target outflow is greater than the corresponding reserve flow lower limit, the cumulative water volume to be compensated is allocated according to the proportion of the water volume that can be reduced in each period to the total water volume that can be reduced in that scheduling day.

[0039] When the total available water volume for the scheduling day is less than the cumulative water volume to be compensated, the uncompensated cumulative water volume to be compensated will be carried over to the next scheduling day, and compensation will be carried out during the period when the target discharge flow is greater than the corresponding reserve flow lower limit on the next scheduling day.

[0040] Furthermore, when the power generation water consumption rate of multiple candidate values ​​of spinning reserve load is within the preset calculation accuracy range of the lowest power generation water consumption rate, the minimum value among the multiple candidate values ​​of spinning reserve load is selected as the spinning reserve load.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] This invention uses the minimum active power output of the operating unit undertaking the spinning reserve task as the spinning reserve load optimization variable and iterates through multiple candidate values. It can achieve a balance between avoiding the unit being in a low-load, low-efficiency zone for a long time and retaining sufficient upward adjustment space. By converting the spinning reserve load into a time-varying lower limit of the spinning reserve flow based on the real-time generator head and the relationship between the unit head, active power output and flow through the unit, the spinning reserve load can be matched with the actual hydraulic characteristics of the unit, avoiding calculation deviations caused by using a fixed flow threshold.

[0043] By setting a cumulative amount of water to be compensated and compensating during subsequent periods when there is room for flow reduction, the total outflow during the scheduling period can be kept constant. This allows for comparison of power generation water consumption rates among candidate schemes under the same total water consumption conditions, reducing optimization deviations caused by inconsistent comparison boundaries. By updating reservoir capacity, water level, and power generation head periodically and recalculating the lower limit of the rotating reserve flow, a closed-loop iterative relationship can be formed between rotating reserve load, turbine flow, water level, and head. This reflects the impact of flow adjustment in the previous period on subsequent operating boundaries. By uniformly verifying water balance, end-of-period water level, daily water level changes, reservoir capacity, outflow, unit output, vibration zone, rotating reserve load, and upward rotating reserve capacity, schemes that do not meet the requirements for safe reservoir operation or grid reserve can be avoided from being identified as economical operating schemes. Attached Figure Description

[0044] Figure 1 This is a flowchart illustrating the overall process of the method steps of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] In this embodiment, the candidate value of rotating standby load is used as the optimization variable. The process of determining the operating boundary, calculating the corrected discharge flow process, simulating the operation process of the unit and reservoir, screening feasible candidate values, optimizing the power generation water consumption rate, and rolling updates for the remaining scheduling period are performed in sequence. The candidate interval, candidate step size, calculation period length, allowable error of flow back calculation, allowable error of end-of-period water level, daily water level difference limit, allowable error of water volume calculation, preset calculation accuracy of power generation water consumption rate, and rolling update threshold involved in this embodiment are determined based on the reservoir scheduling procedure, unit operation procedure, equipment test data, measurement device accuracy, historical operation data, and power grid scheduling requirements.

[0047] In this embodiment, the target discharge flow and the corrected discharge flow both refer to the power generation discharge flow generated by the operating units. The sum of the flow through each operating unit is the total power generation flow of the plant, which is equal to the corrected discharge flow for the corresponding time period. Ecological discharge, irrigation water supply, flood discharge and other non-power generation outflows are counted separately and are not included in the target discharge flow, the corrected discharge flow, and the total power generation flow of the plant, but are included in the overall water balance of the reservoir.

[0048] In this embodiment, the spinning reserve load refers to the minimum active power output required to be maintained by each operating unit undertaking the spinning reserve task during the spinning reserve period. Each candidate value of the spinning reserve load and its corresponding complete scheduling period simulation result constitute a candidate scheme for the spinning reserve load. For the first... Time period The operating status of the unit is recorded as follows: When powering on Take 1, when stopping. Take 0; the first The actual active power output of the unit under each candidate spinning reserve load scheme is denoted as . , No. The candidate values ​​of the spinning reserve load are denoted as follows: During the spinning reserve period, the operating units undertaking spinning reserve tasks must meet the following requirements:

[0049] (1)

[0050] in, This is the candidate value number for the spinning reserve load. For unit serial number, To calculate the time period sequence number, Indicates the first Under the first spinning reserve load candidate scheme, the first Time period The actual active power output of the generator set. Indicates the first There are two candidate values ​​for spinning reserve load, both in kW or MW. , Indicates the first The set of operating units that are on rotating standby during a given period. The set of rotating standby periods is represented; operating units that do not undertake rotating standby tasks are not subject to the rotating standby load constraints shown in equation (1), but should still meet the constraints of minimum feasible output, maximum available output, maximum flow rate and unit vibration zone.

[0051] Please see Figure 1 This invention provides an adaptive optimization method for spinning reserve load for the economical operation of hydropower stations, comprising the following steps:

[0052] In this embodiment, the scheduling period is set to 24 hours, and each calculation period is set to 1 hour. The hydropower station includes multiple operating units capable of undertaking spinning reserve tasks. Within the same scheduling period, each operating unit undertaking spinning reserve tasks adopts the same spinning reserve load candidate value. The length of the scheduling period is determined based on the power grid scheduling cycle, reservoir regulation capacity, and the validity period of inflow forecast. The length of the calculation period is determined based on the power grid scheduling instruction update cycle, automatic generation control cycle, and the reservoir water level change rate.

[0053] S1. Obtain reservoir operation data, power grid dispatch data and unit operation data. Based on these multiple data, determine the target discharge flow rate for each period of the dispatch period and the power generation head for the first period of the dispatch period. Then set multiple candidate values ​​for spinning reserve load. The candidate value for spinning reserve load is the minimum active power output candidate value that each operating unit undertaking the spinning reserve task needs to maintain during the spinning reserve period.

[0054] Specifically, reservoir operation data includes the current actual water level of the reservoir, the target water level at the end of the scheduling period, the predicted inflow process, the water level-storage capacity relationship curve, the downstream water level at the beginning of the scheduling period, and the original time-by-time outflow process. The current actual water level of the reservoir is obtained by water level measuring devices or hydrological monitoring systems. When there are multiple measuring points, abnormal data are excluded based on the calibration error of the measuring devices and the historical distribution of deviations of normal measuring points. Then, the average or median value of the effective measuring points is used. The target water level at the end of the scheduling period is determined by the reservoir scheduling plan, flood control requirements, or superior scheduling instructions. The predicted inflow process is provided by the hydrological forecasting system and is time-aligned according to the calculation period. The predicted total inflow before and after the conversion remains consistent.

[0055] The water level-storage capacity relationship curve is established using water level and storage capacity data from reservoir design data, measured results, or the operation database. Discrete data is processed using piecewise linear interpolation or monotonic interpolation. The interpolation results should ensure that the storage capacity increases with the rise in water level. When the calculated storage capacity exceeds the effective range of the water level-storage capacity relationship curve, the corresponding spinning reserve load candidate scheme is marked as infeasible. In this embodiment, the downstream water level at the first time period of the scheduling period is the tailrace water level of the hydropower station. It can be the measured value or determined based on the relationship between the total power generation flow and the downstream water level. The original time-by-time discharge flow process can be the current scheduling plan, the results of the previous round of optimization, or the discharge flow process calculated based on the power grid load forecast process.

[0056] Power grid dispatch data includes the power grid load forecasting process, spinning reserve periods, upward spinning reserve capacity requirements, and predetermined output shape. Spinning reserve periods and upward spinning reserve capacity requirements are based on data issued by the power grid dispatching agency. Upward spinning reserve capacity requirements can be fixed values ​​or time-period varying sequences. The predetermined output shape is used to represent the relative distribution of power generation tasks in each time period and can be expressed using planned active power output, power grid load forecast values, or normalized weights.

[0057] The unit operation data includes the unit start-up combination, unit operation status, the correspondence between head-active power output and flow rate, minimum feasible output, maximum available output, maximum flow rate, and vibration zone. The unit start-up combination represents the set of units put into operation at the same time. The unit operation status includes start-up, shutdown, startup, shutdown transition, maintenance lockout, and load limiting status. The unit start-up status represents the start-up or shutdown status of the unit operation status. Units in the startup, shutdown transition, or maintenance lockout status do not participate in the normal flow rate distribution and the calculation of the hydropower station's upward rotation reserve capacity.

[0058] The relationship between head, active power output, and flow rate is referred to as the NHQ relationship of the unit. It can be represented by a three-dimensional characteristic surface, active power output-flow rate curves of multiple head sections, or discrete characteristic data. The NHQ relationship of the unit is based on the on-site test data of the unit or the characteristic data provided by the manufacturer and corrected on-site. The minimum feasible output, maximum available output, maximum flow rate, and vibration zone of the unit are determined according to the unit operating procedures, equipment test results, current equipment status, and historical operating data, respectively.

[0059] The initial reservoir capacity during the scheduling period is determined based on the current actual water level and the water level-storage capacity relationship curve. The target reservoir capacity at the end of the scheduling period is determined based on the target water level and the water level-storage capacity relationship curve. Then, the total inflow during the scheduling period is calculated based on the predicted inflow and duration for each time period. In the absence of inter-basin water replenishment and non-power generation outflow, and assuming negligible water losses due to evaporation and seepage, the target outflow during the scheduling period is calculated using the following formula:

[0060] (2)

[0061] in, The target discharge volume during the scheduling period, This represents the total inflow of water during the scheduling period. To schedule the initial storage capacity, The target reservoir capacity at the end of the period is given, and the unit of each variable is m³. When there is inter-basin water replenishment, the corresponding water replenishment volume is included in the total inflow volume during the scheduling period. When there is ecological discharge, irrigation water supply, flood discharge, or other non-power generation outflow, the corresponding water volume is deducted from the total outflow to obtain the target outflow volume during the scheduling period. When evaporation and seepage volume cannot be ignored, it is determined based on the reservoir surface area, meteorological data, and historical seepage data, and is deducted from the water volume available for power generation.

[0062] According to the predetermined power output pattern or the original time-by-time discharge flow process, the target discharge volume for the scheduling period is proportionally allocated to each calculation time period to obtain the target discharge flow for each time period. After allocation, a total water volume correction is performed so that the sum of the products of the target discharge flow for each time period and the corresponding time period length equals the target discharge volume for the scheduling period. If there is missing data in the original time-by-time discharge flow process, it is supplemented based on data from adjacent time periods, the predetermined power output pattern, or the power grid load forecast process. When using interpolation between adjacent time periods, the interpolation error should be ensured to not exceed the preset allowable error of the flow data determined based on the historical flow change rate and the accuracy of the flow data.

[0063] The current actual water level of the reservoir is used as the upstream water level for the first period of the scheduling period. The power generation head for the first period of the scheduling period is determined based on the difference between the upstream water level and the downstream water level. When head loss needs to be considered, the head loss determined based on the relationship curve between the total power generation flow and the head loss is deducted from the difference between the upstream and downstream water levels. When the actual total power generation flow exceeds the effective range of the head loss relationship curve, the corresponding spinning reserve load candidate scheme is marked as infeasible.

[0064] Multiple candidate values ​​for spinning reserve load are generated sequentially within a preset candidate range and according to a preset step size. In this embodiment, the candidate range is set to 20,000 kW to 200,000 kW, and the preset step size is set to 5,000 kW.

[0065] The lower limit of the candidate interval is determined as follows: the minimum feasible output of each operating unit undertaking the spinning reserve task within the predicted power head range, the upper boundary of the low load and low efficiency zone, and the minimum control output of the automatic power generation control system are determined separately. The maximum value among the above output boundaries of the same unit is determined as the effective minimum output of the unit. Then, the maximum value among the effective minimum outputs of each unit is determined as the lower limit of the candidate interval.

[0066] The upper limit of the candidate interval is determined based on the maximum available output of the unit, the maximum flow through the unit, and the grid's upward spinning reserve capacity requirements. The maximum available output of each operating unit undertaking spinning reserve tasks is determined for each time period within the predicted power generation head range. The minimum value of the maximum available output of the same unit in each time period is taken as the conservative maximum available output of the unit. Then, the minimum value of the conservative maximum available output of each unit is taken as the initial upper limit of the candidate interval. Infeasible spinning reserve load candidate values ​​are eliminated by checking the upward spinning reserve capacity of the hydropower station in each time period.

[0067] The preset step size is determined based on the active power output setting resolution of the automatic generation control system, the active power output measurement error of the unit, the data accuracy of the NHQ relationship of the unit, and the allowable calculation scale. Its value is not less than the larger value between the active power output setting resolution and the active power output measurement error. For each generated spinning reserve load candidate value, an independent time-period operation simulation process is established, and the calculation of the corrected discharge flow in S2 and the calculation of the unit and reservoir operation process in S3 are executed alternately according to the time period sequence of the scheduling period until the entire scheduling period is completed.

[0068] S2. For each candidate value of rotating reserve load, based on the current generation head and the corresponding relationship between the generator head, active power output and flow rate of the unit, calculate the corresponding lower limit of rotating reserve flow rate for each time period, and adjust the target discharge flow rate of each time period across time periods to obtain the corrected discharge flow rate process. Among them, the corrected discharge flow rate of each time period is not lower than the corresponding lower limit of rotating reserve flow rate and the corrected discharge flow rate during the scheduling period is equal to the target discharge flow rate during the scheduling period.

[0069] Specifically, an independent operational simulation process is established for each candidate value of spinning reserve load, and the cumulative water volume to be compensated is initially set to zero. The cumulative water volume to be compensated is used to record the water volume that increases due to meeting the spinning reserve load constraint but has not yet been deducted in subsequent periods. The calculation of the corrected discharge flow rate in step S2 and the operation process of the unit and reservoir in step S3 are executed alternately according to the time period sequence of the scheduling period; for the first Time period, first according to the number The calculation of the generating head for each period involves the lower limit of the standby flow rate and the corrected discharge flow rate. Based on the corrected discharge flow rate, the active power output of each operating unit is calculated, and the reservoir water level and the [unclear - possibly related to a specific time period] are updated. The hydroelectric head for power generation during that period, followed by the next... The time period continues to be calculated.

[0070] According to the time sequence of the scheduling period, based on the current generation head, candidate value of spinning reserve load, and the NHQ relationship of each operating unit undertaking spinning reserve tasks, the lower limit of the spinning reserve flow rate of each unit is determined. When the NHQ relationship of the units is represented by discrete head sections, the corresponding flow rate through the unit is first determined based on the candidate value of spinning reserve load in adjacent head sections, and then interpolated based on the current generation head. If the candidate value of spinning reserve load or the current generation head exceeds the effective range of the NHQ relationship of the units, or if the candidate value of spinning reserve load is higher than the maximum available output of the unit, the corresponding spinning reserve load candidate scheme is marked as infeasible.

[0071] The lower limit of the spinning reserve flow rate of each operating unit undertaking spinning reserve tasks within the same time period is added together to obtain the lower limit of the spinning reserve flow rate for that time period. Operating units not undertaking spinning reserve tasks are not included in the lower limit of the spinning reserve flow rate, but their actual flow rate through the unit should meet the minimum feasible output constraint of the unit. Each time a new calculation period begins, the lower limit of the spinning reserve flow rate of the unit and the lower limit of the spinning reserve flow rate for that time period are re-determined based on the updated generator head.

[0072] When the target discharge flow rate for the current period is lower than the reserve flow rate lower limit, the corrected discharge flow rate for that period is increased to the reserve flow rate lower limit. The difference in flow rate between the corrected discharge flow rate and the target discharge flow rate, along with the water volume corresponding to the period length, is added to the accumulated water volume to be compensated. For example, if the target discharge flow rate for a certain period is 450 m³ / s, the reserve flow rate lower limit is 495 m³ / s, and the period length is 1 hour, then the corrected discharge flow rate is set to 495 m³ / s, and the increased water volume of 162,000 m³ is included in the accumulated water volume to be compensated.

[0073] When the target discharge flow rate in the subsequent period after the formation of the accumulated water volume to be compensated is higher than the corresponding reserve flow rate lower limit, the water volume corresponding to the flow difference between the target discharge flow rate and the reserve flow rate lower limit in that period is determined as the adjustable water volume, and the smaller value between the adjustable water volume and the current accumulated water volume to be compensated is taken as the compensation water volume. The target discharge flow rate in the subsequent period is reduced according to the compensation water volume, and the water volume that has been compensated is deducted from the accumulated water volume to be compensated.

[0074] When multiple eligible subsequent time periods exist within the same scheduling day, a trial calculation is first performed on each subsequent time period after the formation time of the accumulated water volume to be compensated within that scheduling day, based on the current candidate value of the rotating reserve load. This yields the generating head, lower limit of the rotating reserve flow, and the amount of water that can be reduced for each subsequent time period. Then, the accumulated water volume to be compensated is allocated according to the proportion of the water volume that can be reduced in each subsequent time period to the total water volume that can be reduced for that scheduling day. Based on the allocation results, the corrected discharge flow, reservoir capacity, reservoir water level, and generating head calculations for that scheduling day are re-executed. If the difference between the compensation water volume obtained from the two subsequent calculations exceeds the preset allowable error for water volume calculation, the calculation is considered complete. Then, the water volume is redistributed based on the recalculated adjustable volume until the difference does not exceed [the specified value]. .

[0075] When the total amount of water that can be discharged on a given dispatch day is less than the cumulative amount of water to be compensated, the water that has not been compensated will be carried over to the next dispatch day and will continue to be compensated during the period when the target discharge flow is higher than the lower limit of the corresponding reserve flow.

[0076] At the end of the scheduling period, the cumulative amount of water to be compensated should be zero or within the preset allowable error range for water volume calculation. Within the range. The error is determined based on the predicted inflow error, the corrected outflow calculation error, the time period length error, and the reservoir capacity error corresponding to the water level-capacity relationship curve, and must not be less than the comprehensive error of the water measurement and calculation system. Among the candidate rotating reserve load schemes that meet this condition, the corrected outflow for each time period is not lower than the corresponding lower limit of the rotating reserve flow, and the corrected outflow during the scheduling period is equal to the target outflow during the scheduling period, or the difference between the two does not exceed... .

[0077] S3. Based on the corrected downstream flow process, calculate the active power output of the unit, the reservoir water level, the generating head and the upward spinning reserve capacity of the hydropower station corresponding to each spinning reserve load candidate value for each time period. Add the spinning reserve load candidate values ​​that meet the constraints of water balance, end-of-period water level, unit operation and upward spinning reserve capacity to the spinning reserve load feasible candidate set.

[0078] Specifically, in the first period of the scheduling period, the actual flow rate of each operating unit in the unit operation data is used as the initial value for adjusting the unit flow rate. If the actual flow rate of each operating unit cannot be obtained, the initial allocation is made based on the original time-by-time flow discharge process, the unit start-up combination, and the allowable flow rate range of each operating unit. In subsequent periods, the unit flow rate allocation result of the previous period is used as the initial value for adjusting the unit flow rate of the current period.

[0079] Adjust the flow rate of each operating unit according to the corrected discharge flow rate for the current period, so that the sum of the flow rates of each operating unit equals the corrected discharge flow rate. When it is necessary to reduce the total power generation flow rate of the plant, reduce it according to the ratio of the current flow rate of each operating unit to its allowable lower limit. When it is necessary to increase the total power generation flow rate of the plant, increase it according to the ratio of the maximum flow rate of each operating unit to its current flow rate.

[0080] The permissible lower limit of the flow rate for operating units undertaking spinning reserve tasks is the corresponding unit spinning reserve flow rate lower limit. The permissible lower limit of the flow rate for operating units not undertaking spinning reserve tasks is the flow rate passing through the unit corresponding to the minimum feasible output of the unit. When the upward or downward adjustment space of each operating unit is insufficient to complete the adjustment of the power generation flow rate of the entire plant, the corresponding spinning reserve load candidate scheme is marked as infeasible.

[0081] The active power output of each operating unit is determined based on the current generating head, the adjusted unit flow rate, and the NHQ relationship of the unit. When the NHQ relationship of the unit supports reverse lookup, the active power output corresponding to the target flow rate is determined by interpolation. When reverse lookup is not possible, the active power output is calculated by using a binary search method between the minimum feasible output of the unit and the maximum available output under the current generating head.

[0082] The permissible error for the pre-defined flow rate back calculation in the bisection method is denoted as: The flow rate is determined based on the accuracy of the unit's flow measurement device and the interpolation error of the unit's NHQ relationship, and the larger of the two values ​​is taken. The difference between the calculated flow rate through the unit and the target flow rate should not exceed [a certain value]. At that time, the corresponding calculated output is determined as the active power output of the unit.

[0083] If the active power output of a unit, determined based on the flow rate, is located within the unit's vibration zone, then the flow rate of that unit should be adjusted to move its active power output to the boundary of the vibration zone. The resulting flow difference should be distributed to other operating units with adjustable capacity. After the flow difference is redistributed, the active power output of each operating unit should be determined again based on the redistributed flow rate. The unit's vibration zone, allowable output range, and spinning reserve load constraints should be rechecked. After redistribution, the sum of the flow rates of each operating unit should still be equal to the corrected discharge flow rate. If the adjustable capacity of other operating units is insufficient to absorb the flow difference, or if the re-determined active power output of the unit still does not meet the corresponding constraints, the corresponding spinning reserve load candidate scheme should be marked as infeasible.

[0084] Regarding the first The reservoir capacity is updated based on the predicted inflow, corrected outflow, and duration of the current period, considering the candidate rotating reserve load. During periods with no non-power generation outflow, the reservoir capacity is updated according to the following relationship:

[0085] (3)

[0086] in, and They represent the first The first spinning reserve load candidate scheme in the... Initial and second periods The reservoir capacity at the beginning of the period, in m³. Indicates the first Forecast inbound flow for different time periods Indicates the first The first spinning reserve load candidate scheme in the... The corrected discharge flow rate for each time period, both are in m³ / s. Indicates the first Time period length, in units When there is non-power generation outflow, the corresponding non-power generation outflow is deducted from the equation (3).

[0087] The reservoir water level for the next period is determined based on the updated reservoir capacity and water level-capacity relationship curve. The power generation head for the next period is determined based on the upstream water level, downstream water level, and head loss for the next period. The corresponding lower limit of the reserve flow rate is then recalculated based on the power generation head for the next period.

[0088] For the The first rotating reserve load candidate scheme, the... The standby capacity of the hydropower station during the period is:

[0089] (4)

[0090] in, Indicates the first Under the candidate scheme of rotating reserve load, the hydropower station in the first... Upward rotation of reserve capacity during the time period Indicates the first The maximum available output of the generating unit under the corresponding generating head and current equipment status. Indicates the first The first spinning reserve load candidate scheme corresponds to the first Water head for power generation during specific time periods.

[0091] set up Indicates the first The grid's power grid spin-up reserve capacity requirements for each time period should meet the following requirements:

[0092] (5)

[0093] , , and Using the same active power unit, the maximum available output of the unit is determined based on the current generating head, the maximum flow rate through the unit, and the status of the unit equipment.

[0094] Constraint checks are performed on each candidate spinning reserve load scheme. The difference between the water level at the end of the scheduling period and the target water level at the end of the scheduling period should not exceed the allowable error for the water level at the end of the period. , The accuracy of water level measurement, the error calculated from the water level-reservoir capacity relationship curve, and the accuracy of scheduling assessment are all considered. The daily water level change during each scheduling period should not exceed the preset daily water level difference limit. , The values ​​specified in the reservoir operation regulations shall be adopted. If no specific values ​​are specified, they shall be determined based on historical safe operation data and bank slope stability requirements.

[0095] The reservoir capacity should be within the preset upper and lower limits at each time period, the corrected discharge flow should be within the preset discharge flow range, the active power output of the hydropower station and each operating unit should be within the allowable output range, the active power output of each operating unit should not be in the unit vibration zone, during the rotating standby period, the operating units undertaking the rotating standby task should meet equation (1), the upward rotating standby capacity of the hydropower station should meet equation (5), and the cumulative amount of water to be compensated at the end of the dispatch period should not exceed .

[0096] Candidate values ​​of spinning reserve load that simultaneously satisfy the above constraints are added to the feasible candidate set of spinning reserve load, while candidate values ​​of spinning reserve load that do not satisfy any of the constraints are not included in the subsequent comparison of power generation water consumption rate.

[0097] S4. Calculate the power generation water consumption rate based on the total power generation water consumption and total power generation of each candidate value of the spinning reserve load in the feasible candidate set of spinning reserve loads, and determine the spinning reserve load candidate value with the smallest water consumption rate as the spinning reserve load.

[0098] Specifically, for each candidate value of spinning reserve load in the feasible candidate set, the total power generation flow of the plant in each time period of the dispatch period is multiplied by the corresponding time period length and summed to obtain the total power generation water consumption during the dispatch period. The total power generation flow of the plant is equal to the corrected discharge flow of the corresponding time period. Non-power generation water outflow is not included in the total power generation water consumption. The active power output of each operating unit in each time period is multiplied by the corresponding time period length and summed to obtain the total power generation during the dispatch period.

[0099] No. The power generation water consumption rate of each candidate spinning reserve load is calculated according to the following relationship:

[0100] (6)

[0101] in, Indicates the first The power generation water consumption rate of each candidate spinning reserve load scheme, in m³ / kWh. This represents the total water consumption for power generation during the scheduling period, in m³. This represents the total power generation during the dispatch period, in kWh. When the value equals zero, the corresponding spinning reserve load candidate scheme is marked as infeasible.

[0102] Calculate the power generation water consumption rate for each candidate value in the feasible candidate set of spinning reserve loads, and determine the spinning reserve load candidate value with the lowest power generation water consumption rate as the spinning reserve load. This is done when the difference between the power generation water consumption rate of multiple candidate values ​​and the lowest power generation water consumption rate does not exceed the preset calculation accuracy of the power generation water consumption rate. When the minimum value is selected, the candidate value of the spinning reserve load is chosen. The error is determined based on the calculation error of total power generation water consumption and the measurement error of total power generation, and is not less than the comprehensive power generation water consumption rate error formed by the flow measurement error, time period length error, active power measurement error, and water level-storage capacity relationship curve error.

[0103] S5. When the reservoir operation data, power grid dispatch data, or unit operation data change, obtain the updated reservoir operation data, power grid dispatch data, and unit operation data, and redetermine the spinning reserve load for the remaining dispatch period based on the updated data.

[0104] Specifically, when hydrological forecasts, power grid load predictions, dispatch plans, current actual reservoir water levels, unit operating combinations, unit operating status, or power grid upward spinning reserve capacity requirements are updated, the remaining spinning reserve load for the dispatch period is recalculated. To reduce redundant calculations caused by measurement fluctuations, water level change thresholds, predicted total inflow water change ratios, and power grid upward spinning reserve capacity change thresholds can be set based on water level measurement accuracy, historical hydrological forecast errors, power grid dispatch command resolution, and minimum stable adjustment of units. When the unit operating combinations change or when the operating units undertaking spinning reserve tasks experience malfunctions, maintenance, or load limiting, recalculation is directly triggered.

[0105] The actual reservoir water level at the update time is used as the initial water level for the remaining scheduling period. The original target water level at the end of the scheduling period or the updated target water level at the end of the remaining scheduling period is used as the target water level at the end of the remaining scheduling period. The predicted inflow process, the predicted grid load process, the spinning reserve period, the unit start-up status, and the grid upward spinning reserve capacity requirements after the update time are extracted to form the calculation boundary for the remaining scheduling period. The cumulative water volume to be compensated after the update time in the previous round of calculation is no longer directly used, and the cumulative water volume to be compensated for the remaining scheduling period is reset to zero. The flow adjustment and water volume changes that have occurred before the update time are reflected by the actual reservoir water level at the update time.

[0106] Based on the remaining scheduling period calculation boundaries, the following steps are re-executed: determining the target discharge volume, allocating the target discharge flow, calculating the lower limit of the spinning reserve flow, compensating for water volume across time periods, allocating the flow through the generating units, determining the active power output of the generating units, updating the reservoir water level and power generation head, verifying the upward spinning reserve capacity of the hydropower station, and calculating the power generation water consumption rate. A new feasible candidate set of spinning reserve loads is established, and the spinning reserve load for the remaining scheduling period is determined. The newly determined spinning reserve load replaces the previous spinning reserve load and is used as the spinning reserve load under the current operating boundary.

[0107] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An adaptive optimization method for spinning reserve load for the economic operation of hydropower stations, characterized in that, Includes the following steps: S1. Obtain reservoir operation data, power grid dispatch data and unit operation data. Based on these multiple data, determine the target discharge flow rate for each period of the dispatch period and the power generation head for the first period of the dispatch period. Then set multiple candidate values ​​for rotating reserve load. The candidate value for rotating reserve load is the minimum active power output candidate value that each operating unit undertaking the rotating reserve task needs to maintain during the rotating reserve period. S2. For each candidate value of rotating reserve load, based on the current generation head and the corresponding relationship between the generator head, active power output and flow rate of the unit, calculate the corresponding lower limit of rotating reserve flow rate for each time period, and adjust the target discharge flow rate of each time period across time periods to obtain the corrected discharge flow rate process. Among them, the corrected discharge flow rate of each time period is not lower than the corresponding lower limit of rotating reserve flow rate and the corrected discharge flow rate during the scheduling period is equal to the target discharge flow rate during the scheduling period. S3. Based on the modified discharge flow process, calculate the active power output of the unit, the reservoir water level, the generating head and the upward spinning reserve capacity of the hydropower station corresponding to each spinning reserve load candidate value for each time period, and add the spinning reserve load candidate values ​​that meet the constraints of water balance, end-of-period water level, unit operation and upward spinning reserve capacity to the spinning reserve load feasible candidate set. S4. Calculate the power generation water consumption rate based on the total power generation water consumption and total power generation of each rotating reserve load candidate value in the feasible candidate set of rotating reserve loads, and determine the rotating reserve load candidate value with the smallest water consumption rate as the rotating reserve load. S5. When the reservoir operation data, power grid dispatch data, or unit operation data change, obtain the updated reservoir operation data, power grid dispatch data, and unit operation data, and redetermine the spinning reserve load for the remaining dispatch period based on the updated data.

2. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 1, characterized in that, The reservoir operation data includes the current actual water level, the target water level at the end of the scheduling period, the predicted inflow process, the water level-storage capacity relationship curve, the downstream water level at the beginning of the scheduling period, and the original time-by-time outflow process; the power grid scheduling data includes the power grid load forecast process, the spinning reserve period, the power grid upward spinning reserve capacity requirements, and the predetermined output shape; the unit operation data includes the unit start-up combination, the unit operating status, the correspondence between head-active power output and through-flow, the unit's minimum feasible output, the unit's maximum available output, the unit's maximum through-flow, and the unit's vibration zone.

3. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 2, characterized in that, The determination of the target outflow for each period of the scheduling period and the hydropower head for the first period of the scheduling period includes: The initial reservoir capacity and the target reservoir capacity at the end of the scheduling period are calculated based on the current actual water level of the reservoir, the target water level at the end of the scheduling period, and the water level-reservoir capacity relationship curve. The target discharge volume for the scheduling period is determined based on the initial reservoir capacity, the target final reservoir capacity, and the predicted inflow process. The target discharge volume for the scheduling period is then allocated to each time period of the scheduling period according to the established power output pattern or the original time-by-time discharge flow process. The current actual water level of the reservoir is used as the upstream water level for the first period of the scheduling period. The upstream and downstream water levels for the first period of the scheduling period are calculated to obtain the power generation head for the first period of the scheduling period.

4. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 3, characterized in that, The process of setting multiple candidate values ​​for spinning reserve load and calculating the corresponding lower limit of spinning reserve flow for each candidate value on a time-period basis includes: Multiple candidate values ​​for spinning reserve load are generated within a preset candidate interval according to a preset step size. The same candidate value for spinning reserve load is used by each operating unit undertaking spinning reserve tasks within the same scheduling period. According to the time sequence of the scheduling period, based on the current generation head and the correspondence between the head, active power output and flow rate of each operating unit undertaking the spinning reserve task, calculate the lower limit of the unit spinning reserve flow rate of each operating unit undertaking the spinning reserve task under each spinning reserve load candidate value. The sum of the lower limits of the spinning standby flow rates of all operating units undertaking spinning standby tasks within the same time period is determined as the lower limit of the spinning standby flow rate for that time period.

5. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 4, characterized in that, The cross-time adjustment of the target discharge flow for each time period includes: When the target discharge flow rate for a certain period is less than the corresponding reserve flow rate lower limit, the corrected discharge flow rate for that period is determined as the reserve flow rate lower limit, and the water volume increased by the corrected discharge flow rate relative to the target discharge flow rate is included in the cumulative water volume to be compensated. When the target discharge flow rate in a subsequent period is greater than the corresponding reserve flow rate lower limit, the water volume corresponding to the flow rate difference between the target discharge flow rate and the reserve flow rate lower limit in the subsequent period is taken as the adjustable water volume. The compensation water volume is obtained based on the smaller value between the adjustable water volume and the cumulative water volume to be compensated. The target discharge flow rate in the subsequent period is reduced according to the compensation water volume, and the compensation water volume is deducted from the cumulative water volume to be compensated.

6. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 5, characterized in that, The calculation of the unit active power output, reservoir water level, generating head, and hydropower station upward spinning reserve capacity corresponding to each time-period candidate value of spinning reserve load includes: The flow rate through each operating unit is adjusted according to the corrected discharge flow rate for each time period. Based on the adjusted flow rate through the unit, the generating head for the corresponding time period, and the correspondence between the unit head, active power output, and flow rate through the unit, the active power output of each operating unit is determined. The sum of the flow rates through each operating unit is the total power generation flow rate of the plant and is equal to the corrected discharge flow rate for the corresponding time period. The reservoir capacity is updated based on the predicted inflow and the adjusted total power generation flow of the plant. The reservoir level is determined based on the updated reservoir capacity. The upstream and downstream water levels are calculated to obtain the power generation head for the next period. The lower limit of the reserve flow for the next period is calculated based on the power generation head for the next period. Calculate the difference between the maximum available output and the actual active power output of each operating unit undertaking the spinning reserve task at the corresponding generating head, and sum them up to obtain the upward spinning reserve capacity of the hydropower station. Candidate values ​​for spinning reserve load that simultaneously meet the following constraints will be added to the feasible candidate set of spinning reserve load: the water level at the end of the scheduling period reaches the target water level at the end of the scheduling period, the water level change on each scheduling day does not exceed the preset daily water level difference limit, the reservoir capacity is within the preset upper and lower limits of the reservoir capacity, the outflow is within the preset outflow range, the active power output of the hydropower station and each operating unit is within the allowable output range, the active power output of each operating unit is not in the unit vibration zone, the active power output of the operating unit undertaking the spinning reserve task is not lower than the candidate value of spinning reserve load, the upward spinning reserve capacity of the hydropower station is not lower than the upward spinning reserve capacity requirement of the power grid, and the cumulative amount of water to be compensated at the end of the scheduling period is zero or within the preset allowable error range of water volume calculation.

7. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 6, characterized in that, The calculation of power generation water consumption rate and determination of spinning reserve load includes: The total power generation flow of the plant during each period of the scheduling period is summed up to obtain the total power generation water consumption for each candidate value of spinning reserve load. The total power generation of each operating unit during each time period is obtained by summing the product of the active power output of each unit during the scheduling period and the corresponding time period length. The power generation water consumption rate is obtained by calculating the ratio of total power generation water consumption to total power generation, and the candidate value of spinning reserve load with the lowest water consumption rate is selected.

8. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 2, characterized in that, The step of re-determining the spinning reserve load for the remaining scheduling period based on the updated data includes: When hydrological forecasts, power grid load predictions, dispatch plans, current actual reservoir water levels, unit start-up combinations, or power grid upward rotation reserve capacity requirements are updated, the actual reservoir water level at the time of the update is recorded as the initial water level for the remaining dispatch period. The predicted inflow process, power grid load prediction process, spinning reserve period, unit start-up status and power grid upward spinning reserve capacity requirements after the update time are extracted and together with the initial water level and the target end water level of the remaining scheduling period to form the calculation boundary of the remaining scheduling period. Based on the calculation boundary of the remaining dispatch period, a feasible candidate set of spinning reserve load is re-established, the power generation water consumption rate of each spinning reserve load candidate value is calculated, and the spinning reserve load for the remaining dispatch period is determined.

9. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 5, characterized in that, When there are multiple periods within the same scheduling day where the outflow from the target exceeds the corresponding reserve flow lower limit, the cumulative water volume to be compensated is allocated according to the proportion of the water volume that can be reduced in each period to the total water volume that can be reduced in that scheduling day. When the total available water volume for the scheduling day is less than the cumulative water volume to be compensated, the uncompensated cumulative water volume to be compensated will be carried over to the next scheduling day, and compensation will be carried out during the period when the target discharge flow is greater than the corresponding reserve flow lower limit on the next scheduling day.

10. The adaptive optimization method for spinning reserve load for economic operation of hydropower stations according to claim 7, characterized in that, When the power generation water consumption rate of multiple candidate values ​​of rotating reserve load is within the preset calculation accuracy range of the lowest power generation water consumption rate, the minimum value among the multiple candidate values ​​of rotating reserve load is selected as the rotating reserve load.

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