Automatic optimization power generation control system based on water level change rate

Abstract

The present invention discloses an automatic optimization power generation control system based on the water level change rate. The automatic optimization power generation control system reads real-time data from the monitoring system for calculation and analysis, performs condition judgment at regular intervals, and sends control operations such as startup, shutdown, and load adjustment to the monitoring system. The monitoring system then sends it to the local control unit LCU for unit power generation control. The load adjustment control is based on the water balance principle: inflow water volume - outflow water volume = change in reservoir water storage volume. If the water level rises, it indicates that the outflow water volume is less than the inflow water volume. Under normal head conditions, the load can be appropriately increased; if the water level drops, it indicates that the outflow water volume is greater than the inflow water volume. When the water level is less than a limited value, the load can be reduced according to the water level drop rate. According to this principle, under the current load condition, the hourly change rate of the water level is calculated. The present invention provides a strong guarantee for the realization of unmanned and undermanned operation of hydropower stations.

Description

Technical Field

[0001] The invention relates to the technical field of power generation control systems, and in particular to an automatic optimization power generation control system based on water level change rate. Background Art

[0002] For runoff hydropower plants without regulating reservoirs, the upstream water supply is unknown, and the on-duty personnel need to frequently observe the water level changes and adjust the load. When the water supply increases, the load needs to be increased. When the water level exceeds the maximum value, it is necessary to promptly increase the unit to generate electricity, otherwise overflow will occur and cause water abandonment. When the water supply decreases, the load needs to be reduced. When the water level is lower than the minimum value, it is necessary to promptly shut down and reduce the load, otherwise the head will drop and the unit's power generation efficiency will decrease.

[0003] In view of the above situation, we independently designed and developed an automatic optimization power generation control system based on the water level change rate, which mainly performs load adjustment control and power factor control by calculating and analyzing the water level change rate in the recent period, and performs automatic start and stop operations and load distribution control by predicting the water level value in the future. The power station can maximize the use of incoming water, not discard water or discard less water, keep the unit running at a higher head, and achieve the best unit efficiency. Summary of the invention

[0004] The object of the present invention is to provide an automatic optimization power generation control system based on the water level change rate to solve the problems raised in the above background technology.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: an automatic optimization power generation control system based on the water level change rate, the automatic optimization power generation control system reads real-time data from the monitoring system for calculation and analysis, performs condition judgment at regular intervals, and sends control operations such as startup, shutdown, and load adjustment to the monitoring system, which is then sent to the local control unit LCU for unit power generation control. The load adjustment control is based on the water balance principle: the amount of water entering the reservoir - the amount of water leaving the reservoir = the change in the amount of water stored in the reservoir. If the water level rises, it indicates that the amount of water leaving the reservoir is less than the amount of water entering the reservoir. Under normal head conditions, the load can be appropriately increased; if the water level drops, it indicates that the amount of water leaving the reservoir is greater than the amount of water entering the reservoir. When the water level is less than the limit value, the load can be reduced according to the rate of water level drop. According to this principle, under the current load, the hourly change rate of the water level is calculated, and the load is adjusted according to the speed of the water level rise or fall, that is, the hourly change rate, to keep the water level stable as much as possible. The automatic optimization power generation control system includes the following steps: calculation of the water level change rate, load adjustment, automatic startup processing, and automatic shutdown processing.

[0006] Preferably, for the calculation of the water level change rate, the system collects the water level point every 5 seconds and stores it in a real-time data container, and processes the data in the container with a standard score algorithm every 5 minutes to filter out abnormal values. The standard score algorithm is shown in the following formulas 1 and 2.

[0007] (1)

[0008] (2)

[0009] Where Xi represents the water level sampling value, is the average value of all water level sampling values ​​within 5 minutes, n is the number of data, S is the standard deviation, and Z is the standard score. When the standard score of the sampling value exceeds the limit, it will be deleted.

[0010] Then calculate the average value WLi of the remaining water level sampling values ​​and store WLi in the minute container. The water level change rate WLRoc can be calculated in the first 30 minutes of the system's operation. The water level change rate for the past half hour is calculated every 5 minutes thereafter, and the data from half an hour ago in the container is cleared. The WLRoc calculation method is shown in Formula 3.

[0011] (3)

[0012] If the machine is started or stopped and the load is adjusted, the water level will change greatly. At this time, all historical water level data in the container will be cleared and the water level change rate will be calculated again.

[0013] Preferably, the load adjustment, the automatic power generation control program calls the load adjustment program every 10 minutes, determines the current water level value, water level change rate and water head, and adjusts the unit output when the three data reach the set limit at the same time, so that the outflow flow and the inflow flow reach a relative balance, and the water level change rate approaches zero. The 10-minute interval, water level, water level change rate and water head setting limit can avoid frequent load adjustment.

[0014] Preferably, in order to avoid water abandonment, the automatic startup process predicts the water level value WLf20 after 20 minutes, that is, the current water level plus the water level rise value in 20 minutes, as shown in Formula 4. When WLf20 exceeds the set maximum water level and the load of the unit reaches the set limit, the unit is added. The water level value after 20 minutes is selected for judgment, because the startup and shutdown control program runs once every 10 minutes, and 20 minutes can effectively avoid the prediction of the water level at a critical value and fail to respond in time.

[0015] (4)

[0016] Boot process:

[0017] First, find out the optimal combination that matches the currently running units, that is, the combination with the smallest unit combination change and the highest efficiency priority. Then switch all units to automatic mode, issue a start-up order, and when the units are connected to the grid, calculate the active power setting value of each unit based on the water level change rate WLRoc, as shown in Formula 5. The method adopted is to allocate in proportion to the unit capacity, and then set the active power setting value of each unit. The local control unit of the unit automatically adjusts the load to the set value, and then the power factor control program automatically sets the constant power factor value based on the active value.

[0018] (5).

[0019] Preferably, in the automatic shutdown process, when the water level is lower than the set minimum value, the water head begins to slowly drop below the rated water head, and when the total active power is lower than the minimum value, the unit with the lowest efficiency is selected in the current unit combination for shutdown operation. After the shutdown order is issued, the total active power setting value of the whole plant Pset=Pmax*0.95 is calculated and then distributed to the running units.

[0020] The present invention provides an automatic optimization power generation control system based on the water level change rate, which has the following beneficial effects: predicting the future water level according to the water level change rate for startup operation; adjusting the load according to the water level change rate, and successfully realizing automatic optimization of power generation control according to the water level change rate, ensuring the economical, safe and stable operation of the power station, reducing the operating cost of the hydropower station, and providing a strong guarantee for the hydropower station to achieve unmanned or less-manned operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the framework structure of the automatic optimization power generation control system of the present invention;

[0022] Figure 2 This is a schematic diagram of the process structure of the automatic optimization power generation control system of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] See also Figure 1-2 The present invention provides a technical solution: an automatic optimization power generation control system based on the water level change rate. The automatic optimization power generation control system reads real-time data from the monitoring system for calculation and analysis, performs condition judgment at regular intervals, and sends control operations such as startup, shutdown, and load adjustment to the monitoring system. The monitoring system then sends it to the local control unit LCU for unit power generation control. The load adjustment control is based on the water balance principle: the amount of water entering the reservoir - the amount of water leaving the reservoir = the change in the amount of water stored in the reservoir. If the water level rises, it indicates that the amount of water leaving the reservoir is less than the amount of water entering the reservoir. Under normal head conditions, the load can be appropriately increased; if the water level drops, it indicates that the amount of water leaving the reservoir is greater than the amount of water entering the reservoir. When the water level is less than the limit value, the load can be reduced according to the rate of water level drop. According to this principle, under the current load, the hourly rate of change of the water level is calculated, and the load is adjusted according to the speed of the water level rise or fall, that is, the hourly rate of change, to keep the water level running smoothly as much as possible. The automatic optimization power generation control system includes the following steps: calculation of the water level change rate, load adjustment, automatic startup processing, and automatic shutdown processing;

[0027] Load adjustment control

[0028] According to the water balance principle: water inflow - water outflow = change in reservoir water storage, if the water level rises, it means that the water outflow is less than the water inflow, and under normal head conditions, the load can be appropriately increased; if the water level drops, it means that the water outflow is greater than the water inflow, and when the water level is less than the limit, the load can be reduced according to the rate of water level drop. According to this principle, under the current load, the hourly rate of change of the water level is calculated, and the load is adjusted according to the rate of water level rise or fall, that is, the hourly rate of change, to keep the water level as stable as possible.

[0029] 1. Calculation of water level change rate

[0030] Because water level fluctuations produce sawtooth oscillations or sudden changes in values, the water level data needs to be processed by a filtering algorithm.

[0031] (1) The system collects the water level point every 5 seconds and stores it in a real-time data container. The data in the container is processed by a standard score algorithm every 5 minutes to filter out abnormal values. The standard score algorithm is shown in the following formulas 1 and 2.

[0032] (1)

[0033] (2)

[0034] Where Xi represents the water level sampling value, is the average value of all water level sampling values ​​within 5 minutes, n is the number of data, S is the standard deviation, and Z is the standard score. When the standard score of the sampling value exceeds the limit, it will be deleted.

[0035] (2) Calculate the average value WLi of the remaining water level sampling values ​​and store WLi in the minute container. The water level change rate WLRoc can be calculated in the first 30 minutes of the system's operation. The water level change rate for the past half hour is calculated every 5 minutes, and the data from half an hour ago in the container is cleared. The WLRoc calculation method is shown in Formula 3.

[0036] (3)

[0037] If the machine is started or stopped, and the load is adjusted, the water level will change greatly. At this time, the historical water level data in the container will be cleared, and the water level change rate will be calculated again. The system selects 30 minutes of water level data to calculate the water level change rate, because if the time is too short, such as 10 minutes, it is easy to make a misjudgment. If the time is too long, it will not be able to respond to the water inflow in time, resulting in reduced unit efficiency or reservoir overflow.

[0038] (II) Load adjustment

[0039] The automatic power generation control program calls the load adjustment program every 10 minutes to determine the current water level value, water level change rate and water head. When the three data reach the set limit at the same time, the unit output is adjusted so that the outflow and inflow are relatively balanced and the water level change rate approaches zero. The 10-minute interval, water level, water level change rate and water head set limit can avoid frequent load adjustment.

[0040] Start-stop control strategy

[0041] (I) Automatic startup processing

[0042] In order to avoid water abandonment, the water level value WLf20 after 20 minutes is predicted, that is, the current water level plus the water level rise value in 20 minutes, as shown in Formula 4. When WLf20 exceeds the set maximum water level and the load of the unit reaches the set limit, the unit is added. The water level value after 20 minutes is selected for judgment, because the start-stop control program runs every 10 minutes, and 20 minutes can effectively avoid the predicted water level being at a critical value and not being responded to in time.

[0043] (4)

[0044] Boot process:

[0045] First, find out the optimal combination that matches the currently running units, that is, the combination with the smallest unit combination change and the highest efficiency priority. Then switch all units to automatic mode, issue a start-up order, and when the units are connected to the grid, calculate the active power setting value of each unit based on the water level change rate WLRoc, as shown in Formula 5. The method adopted is to allocate in proportion to the unit capacity, and then set the active power setting value of each unit. The local control unit of the unit automatically adjusts the load to the set value, and then the power factor control program automatically sets the constant power factor value based on the active value.

[0046] (5)

[0047] (II) Automatic shutdown processing

[0048] When the water level is lower than the set minimum value, the water head begins to slowly drop below the rated water head. When the total active power is lower than the minimum value, the unit with the lowest efficiency is selected in the current unit combination for shutdown. After the shutdown order is issued, the total active power setting value of the whole plant Pset=Pmax*0.95 is calculated and then distributed to the running units.

[0049] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. Automatic optimization of power generation control system based on water level change rate. The automatic optimization of power generation control system reads real-time data from the monitoring system for calculation and analysis, makes condition judgments at regular intervals, and sends the start-up, shutdown, and load adjustment control operations to the monitoring system. The monitoring system then sends them to the local control unit LCU for unit power generation control. It is characterized by: The load adjustment control is based on the water balance principle: the amount of water entering the reservoir - the amount of water leaving the reservoir = the change in the water storage capacity of the reservoir. If the water level rises, it means that the amount of water leaving the reservoir is less than the amount of water entering the reservoir. Under normal head conditions, the load is appropriately increased; if the water level drops, it means that the amount of water leaving the reservoir is greater than the amount of water entering the reservoir. When the water level is less than the limit value, the load is reduced according to the rate of water level drop. According to this principle, under the current load, the hourly rate of change of the water level is calculated, and the load is adjusted according to the rate of increase or decrease of the water level, i.e., the hourly rate of change, to keep the water level running smoothly as much as possible. The automatic optimization power generation control system includes the following steps: calculation of the rate of change of the water level, load adjustment, automatic startup processing, and automatic shutdown processing; The water level change rate is calculated by collecting the water level point every 5 seconds and storing it in a real-time data container. The data in the container is processed by a standard score algorithm every 5 minutes to filter out abnormal values. The standard score algorithm is shown in the following formulas 1 and 2: （1） （2） Where Xi represents the water level sampling value, is the average value of all water level sampling values ​​within 5 minutes, n is the number of data, S is the standard deviation, and Z is the standard score. When the standard score of the sampling value exceeds the limit, it will be deleted. Then calculate the average value WLi of the remaining water level sampling values, and store WLi in the minute container. The water level change rate WLRoc is calculated in the first 30 minutes of the system operation. The water level change rate of the past half hour is calculated every 5 minutes, and the data before half an hour in the container is cleared. The calculation method of WLRoc is shown in Formula 3. (3) If the machine is started or stopped, and the load is adjusted, the water level will change greatly. At this time, all the historical water level data in the container will be cleared, and the water level change rate will be calculated again. In order to avoid water abandonment, the automatic startup process predicts the water level value WLf20 after 20 minutes, that is, the current water level plus the water level rise value in 20 minutes, as shown in Formula 4. When WLf20 exceeds the set maximum water level and the load of the unit reaches the set limit, the unit is added and the water level value after 20 minutes is selected for judgment. Because the startup and shutdown control program runs once every 10 minutes, 20 minutes effectively avoids the predicted water level being at a critical value and not being responded to in time; (4) Boot process: First, find out the optimal combination that matches the currently running units, that is, the combination with the smallest unit combination change and the highest efficiency priority, then switch all units' working modes to the automatic state, and issue a start-up order. When the units are connected to the grid, calculate the active power setting value of each unit based on the water level change rate WLRoc, as shown in Formula 5. The method adopted is to allocate in proportion to the unit capacity, and then set the active power setting value of each unit. The local control unit of the unit automatically adjusts the load to the set value, and then the power factor control program automatically sets the constant power factor value according to the active value. (5)。 2. The automatic optimization power generation control system based on water level change rate according to claim 1 is characterized in that: The load adjustment, the automatic power generation control program calls the load adjustment program every 10 minutes to determine the current water level value, water level change rate and water head. When the three data reach the set limits at the same time, the unit output is adjusted to make the outflow and inflow flow reach a relative balance, and the water level change rate approaches zero. The 10-minute interval, water level value, water level change rate and head setting limits avoid frequent load adjustment.

3. The automatic optimization power generation control system based on water level change rate according to claim 1 is characterized in that: In the automatic shutdown process, when the water level is lower than the set minimum value, the water head begins to slowly drop below the rated head. When the total active power is lower than the minimum value, the unit with the lowest efficiency is selected in the current unit combination for shutdown operation. After the shutdown order is issued, the total active power setting value Pset=Pmax*0.95 of the whole plant is calculated and then distributed to the running units.

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