A method, device and system for low valley starting control of a cascade hydropower plant in a river basin

Abstract

The application provides a basin cascade power plant low valley start control method, device and system, the method comprises the following steps: judging whether there is a normal operation interval matching the power grid load in the current power grid load instruction in all cascade power plants according to the normal operation interval of the generator set of each cascade power plant; when there is no matching normal operation interval, calculating the power generation loss of each cascade power plant according to the limited operation interval of the generator set of each cascade power plant; determining the cascade power plant with the minimum power generation loss as the low valley start power plant. The application solves the problems of low control precision and poor universality of the low valley start control method of the cascade power plant in the prior art, not only can control the reservoir water level of the cascade power plant below the warning water level to prevent the risk of flood discharge which seriously affects the economic benefit, but also can accurately control the low valley start of the cascade power plant, and improve the power generation benefit of the cascade power plant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of basin power plant generation control, in particular to a basin cascade power plant low valley start-up control method, device and system. BACKGROUND

[0002] The basin cascade power plant has three power plants (or multiple power plants), the A power plant is located at the uppermost stream, the reservoir is a multi-year regulation reservoir, the generator unit is a mixed flow generator unit, the single machine capacity is 460MW, the generator unit has a wide vibration interval (145MW---300MW), and the generator unit is connected to the 500KV power grid through a switch station after power generation. The B power plant is located at the middle stream, the reservoir is an annual regulation reservoir, the generator unit is a mixed flow generator unit, the single machine capacity is 300MW, the generator unit has a wide vibration interval (75MW---180MW), and the generator unit is connected to the 220KV and 500KV power grids through a switch station after power generation. The C power plant is located at the lower stream, the reservoir is a daily regulation reservoir, the generator unit is an axial flow and propeller type generator unit, the single machine capacity is 86MW, the generator unit has a prohibited operation interval (0MW---30MW), and the generator unit is connected to the 220KV power grid through a switch station after power generation. By analogy, there can be multiple power plants, and the reservoirs of the basin cascade power plants are different, and are connected to power grids of different voltage levels or power grids of different dispatching levels.

[0003] From 10pm to 6am every day is the low valley start-up period, and the power generation benefit of each power plant is an important factor affecting the low valley start-up. When the low valley start-up strategy of the cascade power plant or the power generation plan is prepared with the power generation benefit as the target, the main purpose is to balance the reservoir water level of the cascade power plant, so that the reservoir water level of the cascade power plant is kept at a high level, and then the power generation benefit of the generator unit of the cascade power plant is calculated, so as to prepare the operation mode of the cascade power plant with the highest power generation benefit. At present, the staff usually controls the low valley start-up of the cascade power plant according to experience, so that the control precision is low and the universality is poor, and the control demand of the power plant cannot be met. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a basin cascade power plant low valley start-up control method, device and system, which solves the problems of low control precision and poor universality of the low valley start-up control method of the cascade power plant in the prior art.

[0005] In a first aspect, the present application provides a method for controlling low-valley start-up of cascade hydropower plants. The method comprises: obtaining a current grid load instruction in a low-valley period, a current reservoir water level of each cascade hydropower plant, and a generator set load operation range of each cascade hydropower plant, wherein the generator set load operation range comprises a prohibited operation range, a limited operation range, and a normal operation range; determining whether there is a hydropower plant exceeding a corresponding warning water level among all the cascade hydropower plants according to the current reservoir water level of each cascade hydropower plant; when there is no hydropower plant exceeding the warning water level, determining whether there is a normal operation range matching the grid load in the current grid load instruction among all the cascade hydropower plants according to the normal operation range of the generator set of each cascade hydropower plant; when there is no matching normal operation range, calculating a power generation loss of each cascade hydropower plant according to the limited operation range of the generator set of each cascade hydropower plant; and determining the cascade hydropower plant with the minimum power generation loss as the low-valley start-up hydropower plant.

[0006] Optionally, the calculating of the power generation loss of each cascade hydropower plant according to the limited operation range of the generator set of each cascade hydropower plant comprises: obtaining a first power generation water consumption of the generator set of each cascade hydropower plant in the limited operation range and a second power generation water consumption of the generator set of each cascade hydropower plant in the normal operation range according to the grid load in the current grid load instruction; obtaining a water consumption difference of each cascade hydropower plant according to a difference between the first power generation water consumption and the second power generation water consumption of the generator set of each cascade hydropower plant; and obtaining the power generation loss of each cascade hydropower plant according to a ratio between the water consumption difference and the second power generation water consumption of the generator set of each cascade hydropower plant.

[0007] Optionally, when there is a matching normal operation range, the method further comprises: determining the cascade hydropower plant corresponding to the matching normal operation range as the low-valley start-up hydropower plant.

[0008] Optionally, after the cascade hydropower plant with the minimum power generation loss is determined as the low-valley start-up hydropower plant, the method further comprises: performing a voltage regulation operation on the generator set of the low-valley start-up hydropower plant according to a comparison result of a voltage parameter of the current grid load instruction and an output voltage of the low-valley start-up hydropower plant.

[0009] Optionally, when there is a hydropower plant exceeding the warning water level, the method further comprises: obtaining a first target hydropower plant and a second target hydropower plant according to the current reservoir water level of each cascade hydropower plant, wherein the first target hydropower plant is the hydropower plant whose current reservoir water level exceeds the corresponding warning water level, and the second target hydropower plant is a subordinate hydropower plant of the first target hydropower plant; obtaining a predicted reservoir water level of the second target hydropower plant according to the grid load in the current grid load instruction, a power generation flow of the first target hydropower plant, and the current reservoir water level of the second target hydropower plant; and determining the first target hydropower plant as the low-valley start-up hydropower plant when the predicted reservoir water level of the second target hydropower plant is within a preset range.

[0010] Optionally, if the predicted reservoir water level of the second target power plant is not within the preset range, the method further comprises: dividing the power grid load in the power grid load instruction into a first load and a second load; obtaining a first predicted water level of the first target power plant according to the first load, the power generation flow of the first target power plant and the current reservoir water level of the first target power plant; obtaining a second predicted water level of the second target power plant according to the second load, the power generation flow of the second target power plant and the current reservoir water level of the second target power plant; and determining that the first target power plant and the second target power plant are both low-valley start-up power plants when the first predicted water level and the second predicted water level are both within the corresponding preset range.

[0011] Optionally, the predicted reservoir water level of the second target power plant is obtained according to the power grid load in the power grid load instruction, the power generation flow of the first target power plant and the current reservoir water level of the second target power plant, comprising: obtaining the amount of water used for power generation according to the power grid load in the power grid load instruction and the power generation flow of the first target power plant; obtaining the reservoir change amount of the second target power plant according to the amount of water used for power generation and the reservoir capacity of the second target power plant; and obtaining the predicted reservoir water level of the second target power plant according to the current reservoir water level of the second target power plant and the reservoir change amount.

[0012] Optionally, the method further comprises: obtaining the predicted rainfall in a preset time period; obtaining the predicted water level change amount of each cascade power plant according to the predicted rainfall and the reservoir capacity of each cascade power plant; and obtaining the current reservoir water level of each cascade power plant in the preset time period according to the predicted water level change amount of each cascade power plant and the corresponding initial reservoir water level.

[0013] In a second aspect, the present application provides a low-valley start-up control device for cascade power plants in a river basin, which comprises: a data acquisition module, configured to acquire the current power grid load instruction in a low-valley period, the current reservoir water level of each cascade power plant and the load operation range of the generator set of each cascade power plant, wherein the load operation range of the generator set comprises a prohibited operation range, a limited operation range and a normal operation range; a first judgment module, configured to judge whether there is a power plant exceeding the corresponding warning water level among all the cascade power plants according to the current reservoir water level of each cascade power plant; a second judgment module, configured to judge whether there is a normal operation range matching the power grid load in the current power grid load instruction among all the cascade power plants according to the normal operation range of the generator set of each cascade power plant when there is no power plant exceeding the warning water level; a power generation loss calculation module, configured to calculate the power generation loss of each cascade power plant according to the limited operation range of the generator set of each cascade power plant when there is no matching normal operation range; and a determination module, configured to determine the cascade power plant with the minimum power generation loss as the low-valley start-up power plant.

[0014] In a third aspect, the present application provides a low-valley start-up control system for a cascade hydropower plant in a river basin, which comprises a low-valley start-up control device for the cascade hydropower plant in the river basin; a power grid load instruction receiving device connected to the low-valley start-up control device for the cascade hydropower plant in the river basin, for receiving a power grid load instruction and transmitting the power grid load instruction to the low-valley start-up control device for the cascade hydropower plant in the river basin; a real-time load monitoring device for the cascade hydropower plant connected to the low-valley start-up control device for the cascade hydropower plant in the river basin, for monitoring real-time loads of generating units of the cascade hydropower plant in the river basin; a database connected to the low-valley start-up control device for the cascade hydropower plant in the river basin, for storing the power grid load instruction and the real-time loads of the generating units of the cascade hydropower plant in the river basin; a start-stop decision device connected to the low-valley start-up control device for the cascade hydropower plant in the river basin, for controlling start and stop of the cascade hydropower plant in the river basin; and a load distribution adjustment device connected to the low-valley start-up control device for the cascade hydropower plant in the river basin, for adjusting loads of the cascade hydropower plant in the river basin according to a distribution scheme output by the low-valley start-up control device for the cascade hydropower plant in the river basin.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The present embodiment determines the cascade hydropower plant with the minimum power generation loss as the low-valley start-up power plant through multi-level judgment on the reservoir water level and the load operation range of the generating units of the cascade hydropower plant, so that the reservoir water level of the cascade hydropower plant can be controlled below the warning water level to prevent the risk of flood discharge which seriously affects economic benefits, and the low-valley start-up of the cascade hydropower plant in the river basin is precisely controlled, thereby improving the power generation benefit of the cascade hydropower plant. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Fig. 1 shows a flowchart of a low-valley start-up control method for a cascade hydropower plant in a river basin according to an embodiment of the present application;

[0018] Figure 2 Fig. 2 shows a flowchart of another low-valley start-up control method for a cascade hydropower plant in a river basin according to an embodiment of the present application;

[0019] Figure 3 Fig. 3 shows a flowchart of still another low-valley start-up control method for a cascade hydropower plant in a river basin according to an embodiment of the present application;

[0020] Figure 4 Fig. 4 shows a structural diagram of a low-valley start-up control system for a cascade hydropower plant in a river basin according to an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the purposes, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0022] In a first aspect, the present application provides a method for controlling the start of a cascade hydropower plant during a low valley period, which specifically includes the following embodiments.

[0023] Figure 1 Fig. 1 shows a flowchart of a method for controlling the start of a cascade hydropower plant during a low valley period according to an embodiment of the present application. Figure 1 As shown in Fig. 1, the method specifically includes the following steps.

[0024] In step S101, the current grid load instruction during the low valley period, the current reservoir water level of each cascade hydropower plant, and the load operation range of the generator set of each cascade hydropower plant are obtained.

[0025] In this embodiment, the current grid load instruction includes the grid load and the delivery time length. The grid load is the power demand of the grid, and the delivery time length is the time length within which the delivery needs to be completed. For example, the grid load is 1000 W, and the delivery time length is 2 hours, so the cascade hydropower plant needs to output 1000 W to the grid within 2 hours. Each cascade hydropower plant has a corresponding reservoir, and the reservoir capacity of each cascade hydropower plant can be the same or different.

[0026] In this embodiment, the load operation range of the generator set includes the prohibited operation range, the limited operation range, and the normal operation range. The prohibited operation range refers to the charge range in which the generator set cannot operate. The limited operation range refers to the charge range in which the generator set with large single-machine capacity operates at a small load. The normal operation range refers to the charge range in which the generator set normally operates.

[0027] In step S102, whether there is a power plant exceeding the corresponding warning water level among all the cascade hydropower plants is determined according to the current reservoir water level of each cascade hydropower plant.

[0028] In step S103, when there is no power plant exceeding the warning water level, whether there is a normal operation range matching the grid load in the current grid load instruction among all the cascade hydropower plants is determined according to the normal operation range of the generator set of each cascade hydropower plant.

[0029] In step S104, when there is no matching normal operation range, the power generation loss of each cascade hydropower plant is calculated according to the limited operation range of the generator set of each cascade hydropower plant.

[0030] In the embodiment, when there is a matched normal operation interval, the method further comprises: determining that the cascade power plant corresponding to the matched normal operation interval is the valley start-up power plant.

[0031] In the embodiment, the power generation loss of each cascade power plant is calculated according to the generator set limited operation interval of each cascade power plant, comprising: obtaining the first power generation water consumption of the generator set of each cascade power plant in the limited operation interval and the second power generation water consumption of the generator set of each cascade power plant in the normal operation interval according to the power grid load in the current power grid load instruction; obtaining the water consumption difference of each cascade power plant according to the difference between the first power generation water consumption and the second power generation water consumption of each cascade power plant; and obtaining the power generation loss of each cascade power plant according to the ratio of the water consumption difference of each cascade power plant to the second power generation water consumption.

[0032] It should be noted that generally, a large-scale mixed-flow generator set has two limited operation intervals. The generator set cannot run in the limited operation interval for a long time, but can only pass through the limited operation interval for a short time. In the limited operation interval, the operating condition of the generator set is poor, the vibration is intensified, and the swing is intensified, which seriously affects the safe and stable operation of the generator set. Due to the limitation of the limited operation interval, when the generator set is running at a small load located in the two limited operation intervals, the load adjustment performance is seriously insufficient, which may cause the generator set to be unable to meet the load instruction. Generally, during the valley period, the power grid has small electricity demand, and the generator set is in a rotating standby state, i.e. a small load running state, and generally runs in the range of the two limited operation intervals. Although the operating condition of the generator set is not good when running in the two limited operation intervals, the generator set can run for a long time. Near the upper limited operation interval, the operating condition of the generator set is relatively good compared with the small load. Therefore, during the valley start-up period, when the power grid load demand is not high, the load of the generator set is preferably increased to below the first limited operation interval.

[0033] During the valley period, the operating load of the generator set is small, and generally, the operating load of the generator set with large capacity is in the two limited operation intervals. When the load needs to be adjusted, the limited operation interval needs to be passed through, and when the load does not need to be adjusted, the operating load of the generator set is preferably close to the lower limit of the first limited operation interval. In the range of the two limited operation intervals, according to the actual operating condition of the generator set, there may be a small load operation interval and a high-efficiency operation interval under the limited operation interval, or both may be small load operation intervals. Because the valley operation time is relatively long, when running in the interval, the operating load is preferably increased to be close to the lower limit of the limited operation interval.

[0034] In step S105, the cascade power plant with the minimum power generation loss is determined as the valley start-up power plant.

[0035] Compared with the prior art, the embodiment has the following beneficial effects:

[0036] The embodiment determines the cascade hydropower plant with the minimum power generation loss as the low-valley start-up hydropower plant through multi-stage judgment on the reservoir water level and the load operation range of the generator set of the cascade hydropower plant, so that the reservoir water level of the cascade hydropower plant can be controlled below the warning water level to prevent the risk of flood discharge that seriously affects economic benefits, and the low-valley start-up of the cascade hydropower plant in the basin is precisely controlled, and the power generation benefit of the cascade hydropower plant is improved.

[0037] Figure 2 As shown in the flowchart of the control method for the low-valley start-up of the cascade hydropower plant in the basin provided by the embodiment of the application, when there is a hydropower plant exceeding the warning water level, the control method further includes the following steps: Figure 2 As shown in the flowchart of the control method for the low-valley start-up of the cascade hydropower plant in the basin provided by the embodiment of the application, when there is a hydropower plant exceeding the warning water level, the control method further includes the following steps:

[0038] In step S201, the first target hydropower plant and the second target hydropower plant are obtained according to the current reservoir water level of each cascade hydropower plant.

[0039] In the embodiment, the first target hydropower plant is the hydropower plant whose current reservoir water level exceeds the corresponding warning water level, and the second target hydropower plant is the hydropower plant downstream of the first target hydropower plant; wherein the warning water level is the higher warning water level, that is, the first target hydropower plant is the hydropower plant whose current reservoir water level exceeds the warning water level among all the reservoir water levels; according to the upstream and downstream arrangement of the cascade hydropower plants in the basin, the hydropower plant downstream of the first target hydropower plant is the second target hydropower plant.

[0040] It should be noted that when the water level of part of the cascade hydropower plants is high, the water level needs to be controlled in time to avoid the situation of flood discharge caused by the high water level. Whether in the flood season or the non-flood season, the low-valley period or the peak period, the reservoir water level of the cascade hydropower plant needs to be controlled in priority to avoid the occurrence of the situation of flood discharge. Therefore, when the water level is high and a certain distance from the limited water level, the reservoir water level needs to be controlled through power generation. When the reservoir water level of part of the cascade hydropower plants is high, attention needs to be paid to the power generation of the upstream and downstream hydropower plants when the water level is controlled through power generation, and the two adjacent cascade hydropower plants, wherein the upstream hydropower plant will cause the water level of the downstream hydropower plant to continuously rise when generating power in the low valley, which is easy to cause the situation of water level exceeding the limit or flood discharge. Therefore, when the low-valley start-up and shutdown strategy of the cascade hydropower plant is prepared, attention needs to be paid to the influence of the power generation of the upstream and downstream hydropower plants on the reservoir water level of the cascade hydropower plant.

[0041] Therefore, when the first target hydropower plant is the last cascade hydropower plant, there is no second target hydropower plant, and the first target hydropower plant is directly determined as the low-valley start-up hydropower plant; when the first target hydropower plant is not the last cascade hydropower plant, after the first target hydropower plant starts up in the low valley, the water in the reservoir of the first target hydropower plant will flow to the downstream hydropower plant, so that the reservoir water level of the second target hydropower plant rises.

[0042] In step S202, the predicted reservoir water level of the second target power plant is obtained according to the power grid load in the current power grid load instruction, the power generation flow of the first target power plant and the current reservoir water level of the second target power plant.

[0043] In the embodiment, the predicted reservoir water level of the second target power plant is obtained according to the power grid load in the current power grid load instruction, the power generation flow of the first target power plant and the current reservoir water level of the second target power plant, including: obtaining the water consumption for power generation according to the power grid load in the current power grid load instruction and the power generation flow of the first target power plant; obtaining the reservoir change of the second target power plant according to the water consumption for power generation and the reservoir capacity of the second target power plant; obtaining the predicted reservoir water level of the second target power plant according to the current reservoir water level of the second target power plant and the reservoir change.

[0044] It should be noted that the water consumption for power generation of the first target power plant is obtained by multiplying the power grid load by the power generation flow, the reservoir change of the second target power plant is obtained by dividing the water consumption for power generation by the reservoir capacity of the second target power plant, and the predicted reservoir water level of the second target power plant is obtained by adding the current reservoir water level of the second target power plant to the reservoir change; wherein the power generation flow refers to the water consumption for generating unit load power.

[0045] In step S203, if the predicted reservoir water level of the second target power plant is within the preset range, the first target power plant is determined as a low-valley start-up power plant.

[0046] It should be noted that the preset range is below the corresponding warning water level of the second target power plant; in the embodiment, if the predicted reservoir water level of the second target power plant is within the preset range, that is, when the power grid load in the power grid load instruction is all provided by the first target power plant, not only the water level of the first target power plant can be lowered, but also the water level of the downstream power plant will not exceed the corresponding warning water level, thereby achieving the purpose of accurately controlling the low-valley start-up of the cascade watershed power plant, and preventing the risk of flood discharge due to the high reservoir water level of the power plant.

[0047] Figure 3 Fig. 2 shows a flowchart of another watershed cascade power plant low-valley start-up control method provided by the embodiment of the present application, as shown in Figure 3 As shown in Fig. 2, if the predicted reservoir water level of the second target power plant is not within the preset range, the control method further includes the following steps:

[0048] In step S301, the power grid load in the power grid load instruction is divided into a first load and a second load.

[0049] Step S302, obtaining a first predicted water level of the first target power plant according to the first load, a power generation flow of the first target power plant and a current reservoir water level of the first target power plant;

[0050] Step S303, obtaining a second predicted water level of the second target power plant according to the second load, a power generation flow of the second target power plant and a current reservoir water level of the second target power plant;

[0051] Step S304, determining that the first target power plant and the second target power plant are both low-valley start-up power plants when the first predicted water level and the second predicted water level are both within a corresponding preset range.

[0052] It should be noted that if the predicted reservoir water level of the second target power plant is not within the preset range, that is, the power grid load in the current power grid load instruction is all generated by the first target power plant, which will cause the water level of the subordinate power plant to exceed the warning water level, the first target power plant and the second target power plant need to be started up at the same time to reduce the second predicted water level. Among them, the proportion of the first target power plant and the second target power plant carrying the power grid load can be adjusted to achieve the purpose of adjusting the predicted water level, therefore, the first load can be equal to, less than or greater than the second load.

[0053] In another embodiment of the present application, the method further comprises: obtaining a predicted rainfall in a preset time period; obtaining a predicted water level change of each cascade power plant according to the predicted rainfall and a reservoir capacity of each cascade power plant; and obtaining a current reservoir water level of each cascade power plant in the preset time period according to the predicted water level change of each cascade power plant and a corresponding initial reservoir water level.

[0054] It should be noted that strong rainfall occurring at night has a greater impact on the low-valley start-stop strategy, at this time, the reservoir water level caused by rainfall needs to be quickly reduced by increasing the power generation load of the cascade power plant to ensure that the reservoir water level of the cascade power plant is below the normal operation water level. In this case, the cascade power plant will all generate power with large load, which is not within the range of the low-valley start-stop strategy. During the low valley, strong rainfall occurs in the basin, and the reservoir water level of the cascade power plant is relatively high, which is more likely to cause flood discharge. At this time, the reservoir water level of the cascade power plant needs to be quickly reduced by increasing the power generation of the cascade power plant (operation load).

[0055] Therefore, the low-valley starting control during heavy rainfall includes: (1) calculating the expected rainfall: monitoring the rainfall of each area according to the rainfall stations installed in the control area of the cascade hydropower plant; when calculating the rainfall storage of each cascade hydropower plant, the rainfall of the rainfall stations in the range of the cascade hydropower plant and the proportion of the area occupied by the cascade hydropower plant to the control area of the cascade hydropower plant are used to calculate the rainfall of the cascade hydropower plant; after the rainfall is calculated, the subsequent rainfall storage flow, the water volume caused by the rainfall and other data can be calculated accordingly; (2) calculating the water level rise of the cascade hydropower plant caused by the rainfall: after the water volume caused by the current rainfall is calculated, the water level rise caused by the water volume can be calculated according to the reservoir capacity under the current water level of the cascade hydropower plant; (3) calculating the water level rise of the downstream reservoir after the power generation of each cascade hydropower plant: according to the recent or previous day low-valley power generation, mainly the operation load, the water level rise of the power generation of each cascade hydropower plant is calculated, mainly the water level change of the cascade hydropower plant when the cascade hydropower plant does not generate power and the cascade hydropower plant above generates power, and the water level change of each cascade hydropower plant under this condition is calculated in turn; (4) calculating the water level amplitude caused by the rainfall and the water level amplitude caused by the power generation: the water level change caused by the low-valley power generation and the water level change caused by the rainfall are calculated according to the above, and the water level amplitude of each cascade hydropower plant under the condition of the rainfall and the low-valley power generation is calculated; (5) calculating the influence of the total water level amplitude on the low-valley starting operation of the cascade hydropower plant: after the water level amplitude under various conditions is calculated, when the water level of each cascade hydropower plant is below the safe operation water level, the water level of the cascade hydropower plant with a higher water level can be lowered preferentially, or the low-valley starting operation can be determined according to the economic benefits; (6) determining the low-valley starting operation mode of the cascade hydropower plant: the low-valley starting strategy of the cascade hydropower plant includes the starting cascade hydropower plant and the starting and stopping operation mode of the cascade hydropower plant.

[0056] In another embodiment of the present application, after determining that the first target hydropower plant is a low-valley starting hydropower plant, the method further includes: obtaining the low-valley starting time length of the first target hydropower plant according to the transmission time length in the current grid load instruction; obtaining the target control water level of the first target hydropower plant in each preset interval according to the difference between the current reservoir water level and the warning water level of the first target hydropower plant and the low-valley starting time length; and controlling the operation of the corresponding generator set according to the target control water level of each preset interval.

[0057] Optionally, the method further includes: obtaining the control deviation of the current preset interval according to the target control water level and the actual operation water level of the current preset interval; and fusing the control deviation of the current preset interval and the target control water level of the next preset interval to obtain the target control water level of the next preset interval.

[0058] It should be noted that the cascade power plant needs to determine the water level control target according to the actual operation, rainfall, power grid power generation demand, maintenance, weather and other factors in the actual operation process. Therefore, the water level control target is also changed. The water level control target of the cascade power plant is rolling correction. In actual work, there is no fixed time to correct it. Generally, the cascade power plant reservoir water level control target is corrected when needed, for example, strong rainfall today requires correction of the control target; today's high temperature requires correction of the control target; today's water storage requires correction of the control target. Therefore, the water level control target of the cascade power plant is rolling correction and rolling optimization.

[0059] In this embodiment, the calculation basis of the reservoir water level control target is the later rainfall, safe operation water level, and water level balance between cascade power plants. The calculation method is different, and the constraint condition is also different. The same point is to ensure that the water level of the cascade power plant reservoir is below the safe water level, that is, it cannot exceed the highest safe operation water level.

[0060] In the absence of rainfall, the cascade power plant maintains the horizontal balance of the cascade power plant reservoir, that is, the water level of the uppermost power plant reservoir remains unchanged. In the absence of rainfall, only the cascade power plant generation affects the water level of the reservoir. Ensure that the water level of the reservoir of a power plant remains unchanged, that is, the inflow (average flow) of the power plant is equal to the outflow (average flow), that is, the water entering the power plant reservoir is equal to the water flowing out of the power plant reservoir. The inflow of the power plant is the power generation flow of the upper power plant, and the outflow of the power plant is the power generation flow of the power plant.

[0061] The power generation of the cascade power plant F i (i is the cascade power plant number), the power generation flow (average flow) Q corresponding to the power generation of the cascade power plant i (i is the cascade power plant number), the inflow (average flow) Q of the cascade power plant i+1 (i+1 is the number of the upper power plant of the cascade power plant), in order to control the water level balance of the cascade power plant reservoir, it is necessary to make Q i = Q i+1 .

[0062] Due to factors such as water head size and generator set form between each cascade power plant, the power generation water consumption is different, that is, the same 100MW output of each power plant has different power generation flow. In order to match the power generation flow of a power plant with the inflow (power generation flow of the upper power plant), that is, equal, there will be a coefficient β i (i is the cascade power plant number, β i represents the coefficient between the i power plant and the upper power plant), in order to control the water level balance of the cascade power plant reservoir, it is necessary to make Fi+1 = F i β i .

[0063] Generally, the actual operation water level is difficult to reach 100% water level control target, the actual operation water level is closer to the control target, the better the control effect. The actual operation water level may exceed the control target, or may not exceed the control target. Exceeding the water level control target becomes positive deviation, and below the water level control target becomes negative deviation. Positive and negative deviation is only the positive and negative relationship of the numerical value of water level deviation, and does not represent the good and bad of control. The smaller the water level control deviation rate, the better the water level control. For example: the water level control target is 195 meters, after the staff optimization scheduling, the actual operation water level is 194.8 meters, then the water level deviation is negative deviation, or after the staff optimization scheduling, the actual operation water level is 195.3 meters, then the water level deviation is positive deviation, the two actual operation water levels are lower than the safe operation water level, according to the deviation rate, 194.8 meters is controlled better; The water level control deviation rate calculation formula is:

[0064]

[0065] Wherein, H k represents the water level control target, H i represents the actual operation water level, (H i -H k ) represents the water level control deviation; The water level control target is rolling calculated, and the water level control deviation rate is also rolling calculated. Deviation rate represents the effect of water level control, whether it is positive deviation or negative deviation, as long as the smaller the deviation rate, the higher the accuracy of the controlled water level. In the positive deviation, the safe operation water level of the power plant needs to be considered, when the positive deviation is large, when the water level of the power plant is high, the water level needs to be reduced in time to ensure the safe operation water level.

[0066] In another embodiment of the present application, after determining the cascade power plant with the minimum power generation loss as the low valley start-up power plant, the method further comprises: performing voltage regulation operation on the generator set of the low valley start-up power plant according to the comparison result of the voltage parameter of the current power grid load instruction and the output voltage of the current low valley start-up power plant.

[0067] It should be noted that the period when the step power plant voltage regulation mainly occurs is summer and winter, the power demand in summer is larger, the line voltage is lower during the low valley (late night), and part of the generator set of the step power plant needs to be regulated, that is, more reactive power is sent out to improve the line voltage, the power demand in winter is smaller, the line voltage is higher during the low valley (late night), and part of the generator set of the step power plant needs to be regulated, that is, more reactive power is absorbed to reduce the line voltage. Due to the grid system and other reasons, there may be voltage regulation during other low valley periods. During the low valley period, the generator set is used for system voltage regulation, the grid load demand is not large, and the generator set is mainly regulated, so the operation load of the generator set is low, and sometimes the generator set needs to be operated at a small load for a long time, which greatly affects the power generation efficiency. When the generator set absorbs reactive power for voltage regulation, the generator set is operated in a leading phase state, and the stability is poor, and during the low valley period, the load cannot be too large, which leads to the need for the operator to strengthen the monitoring of the generator set operated in the voltage regulation mode.

[0068] Whether the generator set of the step power plant needs to be regulated mainly depends on two aspects: (1) system voltage abnormality, that is, the system voltage is close to the upper limit or lower limit, or has exceeded the upper limit or lower limit, at this time, voltage regulation needs to be performed in time, and when the grid system staff does not order to perform voltage regulation, the staff needs to report to the grid system staff in time, and whether to perform voltage regulation is determined according to the specific situation. (2) The grid system has multiple voltage regulation devices, and whether the step power plant performs voltage regulation is determined by the grid system staff.

[0069] During the low valley period, the power generation demand is small, but during the voltage regulation period, the operation load of the generator set is increased as much as possible, on the one hand to avoid small load operation of the generator set, and on the other hand to improve the stability of the generator set after increasing the operation load of the generator set, which is beneficial to the safe and stable operation of the generator set during voltage regulation.

[0070] In a second aspect, the present application provides a low valley start-up control device for a step power plant in a river basin, and the device comprises:

[0071] A data acquisition module is configured to acquire a current grid load instruction during a low valley period, a current reservoir water level of each step power plant, and a generator set load operation range of each step power plant, wherein the generator set load operation range comprises a prohibited operation range, a limited operation range and a normal operation range.

[0072] A first judgment module is configured to determine whether there is a power plant exceeding a corresponding warning water level among all step power plants according to the current reservoir water level of each step power plant.

[0073] A second judgment module is configured to determine whether there is a normal operation range matching a grid load in the current grid load instruction among all step power plants according to the normal operation range of the generator set of each step power plant when there is no power plant exceeding the warning water level.

[0074] a power generation loss calculation module, configured to calculate power generation loss of each cascade power plant according to the generator set limit operation interval of each cascade power plant when there is no matching normal operation interval;

[0075] a determination module, configured to determine the cascade power plant with the minimum power generation loss as the valley start-up power plant.

[0076] In a third aspect, the present application provides a watershed cascade power plant valley start-up control system, which comprises the watershed cascade power plant valley start-up control device of the above-mentioned embodiments. Figure 4 As shown in the drawings, the system comprises the watershed cascade power plant valley start-up control device of the above-mentioned embodiments.

[0077] a power grid load instruction receiving device connected with the watershed cascade power plant valley start-up control device, configured to receive a power grid load instruction and transmit the power grid load instruction to the watershed cascade power plant valley start-up control device;

[0078] a watershed cascade power plant real-time load monitoring device connected with the watershed cascade power plant valley start-up control device, configured to monitor real-time load of the power generation operation unit of the watershed cascade power plant;

[0079] a database connected with the watershed cascade power plant valley start-up control device, configured to store the power grid load instruction and the real-time load of the power generation operation unit of the watershed cascade power plant;

[0080] a start-up and shutdown decision device connected with the watershed cascade power plant valley start-up control device, configured to control start-up and shutdown of the watershed cascade power plant;

[0081] a load distribution adjustment device connected with the watershed cascade power plant valley start-up control device, configured to adjust load of the watershed cascade power plant according to the distribution scheme output by the watershed cascade power plant valley start-up control device.

[0082] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing relevant hardware through a computer program. The program can be stored in a non-volatile computer readable storage medium, and when the program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to memory, storage, databases, or other media in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0083] It should be noted that, in this document, the terms "first" and "second" and the like are used merely to distinguish one entity or action from another, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element defined by the statement "comprising a" does not exclude the existence of additional identical elements in the process, method, article, or apparatus including the element.

Claims

1. A method for low valley start-up control of a cascade hydropower plant in a river basin, characterized in that, The method comprises: obtaining current power grid load instructions in a valley period, current reservoir water levels of each cascade power plant, and generator set load operation intervals of each cascade power plant, wherein the generator set load operation intervals comprise prohibited operation intervals, limited operation intervals and normal operation intervals; judging whether there is a power plant exceeding a corresponding warning water level among all cascade power plants according to the current reservoir water level of each cascade power plant; when there is no power plant exceeding the warning water level, judging whether there is a normal operation interval matching the power grid load in the current power grid load instructions among all cascade power plants according to the normal operation interval of the generator set of each cascade power plant; when there is no matching normal operation interval, calculating the power generation loss of each cascade power plant according to the limited operation interval of the generator set of each cascade power plant; determining the cascade power plant with the minimum power generation loss as the valley start-up power plant; when there is a power plant exceeding the warning water level, the method further comprises: obtaining a first target power plant and a second target power plant according to the current reservoir water level of each cascade power plant, wherein the first target power plant is a power plant with a current reservoir water level exceeding a corresponding warning water level, and the second target power plant is a lower-level power plant of the first target power plant; obtaining a predicted reservoir water level of the second target power plant according to the power grid load in the current power grid load instructions, the power generation flow of the first target power plant and the current reservoir water level of the second target power plant; if the predicted reservoir water level of the second target power plant is within a preset range, determining the first target power plant as the valley start-up power plant; if the predicted reservoir water level of the second target power plant is not within the preset range, the method further comprises: dividing the power grid load in the power grid load instructions into a first load and a second load; obtaining a first predicted water level of the first target power plant according to the first load, the power generation flow of the first target power plant and the current reservoir water level of the first target power plant; obtaining a second predicted water level of the second target power plant according to the second load, the power generation flow of the second target power plant and the current reservoir water level of the second target power plant; when the first predicted water level and the second predicted water level are both within corresponding preset ranges, determining that the first target power plant and the second target power plant are both valley start-up power plants; obtaining a predicted reservoir water level of the second target power plant according to the power grid load in the power grid load instructions, the power generation flow of the first target power plant and the current reservoir water level of the second target power plant, comprises: obtaining power generation water consumption according to the power grid load in the power grid load instructions and the power generation flow of the first target power plant; obtaining a reservoir change amount of the second target power plant according to the power generation water consumption and the reservoir capacity of the second target power plant; obtaining the predicted reservoir water level of the second target power plant according to the current reservoir water level and the reservoir change amount of the second target power plant.

2. The method of claim 1, wherein the low valley operation control of the cascade hydropower plants is performed by a computer program. calculating the power generation loss of each cascade power plant according to the limited operation interval of the generator set of each cascade power plant, comprises: According to the power grid load in the current power grid load instruction, a first power generation water consumption of a generator set of each cascade hydropower plant in a limit operation interval and a second power generation water consumption of the generator set in a normal operation interval are obtained; According to a difference between the first power generation water consumption and the second power generation water consumption of each cascade hydropower plant, a water consumption difference of each cascade hydropower plant is obtained; According to a ratio of the water consumption difference and the second power generation water consumption of each cascade hydropower plant, a power generation loss of each cascade hydropower plant is obtained.

3. The method of claim 1, wherein the low valley operation control of the cascade hydropower plants is performed by a computer program. When there is a matched normal operation interval, the method further comprises: determining that the cascade hydropower plant corresponding to the matched normal operation interval is a valley start-up hydropower plant.

4. The method of claim 1, wherein the low valley operation control of the cascade hydropower plants is performed by a computer program. After the cascade hydropower plant with the minimum power generation loss is determined as the valley start-up hydropower plant, the method further comprises: According to a comparison result of a voltage parameter of the current power grid load instruction and an output voltage of the current valley start-up hydropower plant, a voltage regulation operation is performed on the generator set of the valley start-up hydropower plant.

5. The method of claim 1, wherein the low valley operation control of the cascade hydropower plants is performed by a computer program. The method further comprises: Obtaining a predicted rainfall in a preset time period; According to the predicted rainfall and a reservoir capacity of each cascade hydropower plant, a predicted water level change of each cascade hydropower plant is obtained; According to the predicted water level change of each cascade hydropower plant and a corresponding initial reservoir water level, a current reservoir water level of each cascade hydropower plant in the preset time period is obtained.

6. A low valley startup control device for a river basin cascade power plant, which adopts the low valley startup control method for a river basin cascade power plant according to claim 1, characterized in that, The device comprises: A data acquisition module is configured to acquire a current power grid load instruction in a valley period, a current reservoir water level of each cascade hydropower plant, and a generator set load operation interval of each cascade hydropower plant, wherein the generator set load operation interval comprises a prohibited operation interval, a limit operation interval, and a normal operation interval; A first judgment module is configured to determine, according to the current reservoir water level of each cascade hydropower plant, whether there is a hydropower plant exceeding a corresponding warning water level among all the cascade hydropower plants; A second judgment module is configured to determine, when there is no hydropower plant exceeding the warning water level, whether there is a normal operation interval matched with the power grid load in the current power grid load instruction among all the cascade hydropower plants according to the normal operation interval of the generator set of each cascade hydropower plant; A power generation loss calculation module is configured to calculate, when there is no matched normal operation interval, a power generation loss of each cascade hydropower plant according to the limit operation interval of the generator set of each cascade hydropower plant; A determination module is configured to determine a cascade hydropower plant with the minimum power generation loss as a valley start-up hydropower plant.

7. A low valley start-up control system for a river basin cascade power plant, characterized by, The control system comprises the watershed cascade hydropower plant valley start-up control device of claim 6; A power grid load instruction receiving device is connected with the watershed cascade hydropower plant valley start-up control device, configured to receive a power grid load instruction and transmit the power grid load instruction to the watershed cascade hydropower plant valley start-up control device; A watershed cascade hydropower plant real-time load monitoring device is connected with the watershed cascade hydropower plant valley start-up control device, configured to monitor real-time loads of watershed cascade hydropower plant generator sets; A database is connected with the watershed cascade hydropower plant valley start-up control device, configured to store power grid load instructions and real-time loads of watershed cascade hydropower plant generator sets; A start-stop decision device is connected with the watershed cascade hydropower plant valley start-up control device, configured to control start-stop of watershed cascade hydropower plants. The load distribution adjustment device is connected with the low-valley start-up control device of the basin cascade power plant, and is used for adjusting the load of the basin cascade power plant according to the distribution scheme output by the low-valley start-up control device of the basin cascade power plant.

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