Cooperative regulation and control method and system for tail water power generation system of sewage treatment plant

Abstract

The invention discloses a cooperative regulation and control method and system for a tail water power generation system of a sewage treatment plant, and the method comprises the steps: monitoring the water level of a drop pool in the tail water power generation system in real time, and obtaining an operation number signal of lifting pumps of an upstream sewage treatment plant, the running quantity determines the total tail water quantity flowing into the tail water power generation system; according to the operation number signal of the lifting pump, the current inflow total tail water amount of the tail water power generation system is recognized, a control strategy matched with the current inflow total tail water amount is called from a preset strategy library, and the control strategy comprises bypass valve reference control logics corresponding to different total tail water amounts; and generating a control instruction for adjusting the opening degree of the bypass valve based on the deviation between the water level of the drop pool and the target water level in combination with the bypass valve reference control logic in the called control strategy so as to maintain the stability of the drop pool at the target water level.

Description

Technical Field

[0001] This invention relates to the field of tailwater power generation technology, and specifically to a collaborative control method and system for a wastewater treatment plant tailwater power generation system. Background Technology

[0002] With the continuous development of renewable energy technologies, the resource utilization of wastewater treatment plant effluent has become an important way to improve energy efficiency and reduce carbon emissions. Utilizing treated wastewater for hydropower generation is widely considered an effective energy-saving measure. However, due to the characteristics of wastewater treatment plant operation, the influent flow rate fluctuates continuously, especially when the booster pumps start and stop irregularly, resulting in irregular effluent discharge flow rates (fluctuating between 6000 and 24000 m³ / h). Such drastic flow rate fluctuations significantly impact the stable operation of downstream wastewater generator units.

[0003] According to relevant technical specifications, the efficiency of hydropower generation, assuming stable active power output from the generator, depends on the product of the turbine's flow rate and operating head. Therefore, the turbine's flow rate and operating head are crucial to power generation efficiency. Traditional tailrace power station operation relies primarily on manual load regulation. Operators need to monitor tailrace flow changes in real time and maintain stable operating head by manually adjusting bypass valve openings. However, this operation mode has several limitations. Manual response is delayed, typically by about 10-12 seconds, preventing the unit from maintaining efficient operation under instantaneous flow changes, thus resulting in power generation efficiency loss. Furthermore, the precision of manual adjustment is limited, making it difficult to keep the turbine in its optimal efficiency range for extended periods. In addition, personnel need to continuously monitor equipment operation, resulting in high workload, and misoperation can lead to frequent unit shutdowns or equipment failures.

[0004] Although there are technologies for automated control of hydropower units, most are designed for conventional hydropower stations and do not fully consider the sudden changes in the flow rate of wastewater treatment plant tailwater caused by the start and stop of booster pumps. Existing control strategies are unable to maintain a stable water level in the forebay (drop pool) under conditions of drastic flow fluctuations, resulting in low power generation efficiency, frequent equipment start-ups and shutdowns, and reduced overall economic efficiency and reliability of the tailwater power generation system. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a collaborative control method that can adapt to changes in flow rate based on the operating status of the upstream sewage treatment plant and meet the optimal working head stability.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for coordinated control of a wastewater treatment plant effluent power generation system includes the following steps: (1) Monitor the water level of the drop pool in the tailwater power generation system in real time and obtain the number of operating pumps of the upstream sewage treatment plant. The pumps are used to increase the influent of the sewage treatment plant, and their number of operation determines the total amount of tailwater flowing into the tailwater power generation system. (2) Based on the number of pumps in operation, identify the total amount of tailwater currently flowing into the tailwater power generation system, and call the control strategy that matches the total amount of tailwater currently flowing into the system from the preset strategy library. The control strategy includes the bypass valve reference control logic corresponding to different total amounts of tailwater. (3) Based on the deviation between the water level of the drop pool and the target water level, and combined with the bypass valve reference control logic in the control strategy called, a control command to adjust the opening of the bypass valve is generated to maintain the stability of the drop pool at the target water level.

[0007] This invention breaks down the information barrier between the tailrace power generation system and the upstream wastewater treatment plant, achieving inter-system collaboration. By acquiring signals from the booster pump to identify the total tailrace volume, it can predict future flow trends before the tailrace enters the drop tank of the tailrace power generation system, thus providing valuable lead time for control decisions. Maintaining stable water levels in the drop tank as the ultimate goal, combined with bypass valve opening control, directly improves the operating head conditions of the turbine, preventing excessive tailrace inflow or excessively low water levels, thereby optimizing the operation of the tailrace power generation system.

[0008] As an optimization, in step (2), the total inflow tailwater volume is identified by mapping the number of operating booster pumps to multiple discrete operating states. This transforms the complex, continuous flow rate change problem into a simple, discrete state judgment problem, greatly simplifying the execution logic of subsequent control strategies.

[0009] As an optimization, in step (2), the bypass valve reference control logic includes at least one of the following: (a) Determine the reference opening degree of the bypass valve based on the total inflow tailwater volume; (b) Set the water level threshold for triggering the bypass valve opening adjustment based on the total inflow tailwater volume; (c) The delay parameter for controlling the change in bypass valve opening is determined based on the change in the total inflow tailwater volume. This strategy of adjusting the bypass valve opening through the coordination of multiple control logics improves system stability.

[0010] As an optimization, in step (3), the step of generating the control command for adjusting the opening of the bypass valve includes: based on the deviation between the water level in the drop tank and the target water level, calculating the water level difference opening adjustment amount of the bypass valve using a PID control algorithm, superimposing the water level difference opening adjustment amount with the reference opening adjustment amount specified in the reference control logic of the bypass valve, and then generating the control command for the final opening adjustment amount of the bypass valve. The reference opening is responsible for quickly responding to the main disturbance, and the adjustment calculated by the PID control algorithm is responsible for eliminating the remaining deviation. This composite control mode overcomes the lag of simple feedback control and makes up for the lack of accuracy of simple feedforward control.

[0011] As an optimization, in step (1), the output power of the tailrace power generation system is also monitored in real time. When the output power is lower than the preset power threshold, steps (2) and (3) are skipped, and a control command to completely close the bypass valve is directly generated. When the power generation is too low, it indicates that the power generation efficiency is low. At this time, the bypass valve is forcibly closed so that all the water flow is used for power generation, which directly improves the power generation revenue.

[0012] As an optimization, in step (1), when the tailrace power generation system receives a shutdown signal, steps (2) and (3) are skipped, and a control command to fully open the bypass valve is directly generated. As an independent safety barrier, regardless of the normal operating state of the system, once a shutdown signal is received (shutdown signals include normal shutdown, emergency shutdown, etc.), the bypass valve is fully opened to ensure that the tailrace discharge channel is completely unobstructed.

[0013] This invention also discloses a coordinated control system for a wastewater treatment plant effluent power generation system, used to execute the coordinated control method described above. The system includes a monitoring module, a signal acquisition module, a decision control module, and an execution module. The monitoring module is used to monitor the operating parameters of the effluent power generation system. The signal acquisition module is used to acquire the operating quantity signal of the upstream wastewater treatment plant's booster pumps. The decision control module is used to receive the operating parameters and the operating quantity signal of the booster pumps, and to call a control strategy that matches the preset strategy library according to the total effluent volume, and to generate a control command to adjust the opening of the bypass valve based on the deviation between the drop tank water level and the target water level. The execution module is used to receive the control command and execute the bypass valve operation.

[0014] As an optimization, the monitoring module is also used to monitor the opening signal of the bypass valve. The opening of the bypass valve is measured by an opening detection device, which includes a detection controller and a sensor. The sensor is installed at the edge of the valve plate of the bypass valve. The sensor is used to detect the rotation angle of the valve plate and output a signal. The detection controller is used to receive the sensor signal and convert the angle change of the valve plate into a rotation opening signal. This valve plate edge detection scheme avoids the cumulative errors caused by clearances and wear from valve shaft transmission, providing a more accurate and linear valve position signal.

[0015] Compared to existing technologies, this invention acquires the operating signals of the upstream booster pump to anticipate changes in the tailrace inflow, achieving a shift from passive response to proactive prediction. By using a pre-set strategy library, complex flow fluctuations are discretized into multiple standard states, enabling the system to maintain efficient and stable operation under various conditions. Detailed Implementation

[0016] The coordinated control method for the wastewater treatment plant effluent power generation system in this specific embodiment includes the following steps: (1) Monitor the water level of the drop pool in the tailwater power generation system in real time and obtain the number of operating pumps of the upstream sewage treatment plant. The pumps are used to increase the influent of the sewage treatment plant, and their number of operation determines the total amount of tailwater flowing into the tailwater power generation system. (2) Based on the number of pumps in operation, identify the total amount of tailwater currently flowing into the tailwater power generation system, and call the control strategy that matches the total amount of tailwater currently flowing into the system from the preset strategy library. The control strategy includes the bypass valve reference control logic corresponding to different total amounts of tailwater. (3) Based on the deviation between the water level of the drop pool and the target water level, and combined with the bypass valve reference control logic in the control strategy called, a control command to adjust the opening of the bypass valve is generated to maintain the stability of the drop pool at the target water level.

[0017] In step (2), the total amount of tailwater flowing in is identified by mapping the number of operations of the booster pump to multiple discretized operating conditions.

[0018] In step (2), the bypass valve reference control logic includes at least one of the following: (a) Determine the reference opening degree of the bypass valve based on the total inflow tailwater volume; (b) Set the water level threshold for triggering the bypass valve opening adjustment based on the total inflow tailwater volume; (c) Based on the change in the total inflow tailwater, control the delay parameter for the change in the opening of the bypass valve.

[0019] In step (3), the step of generating the control command for adjusting the opening of the bypass valve includes: based on the deviation between the water level of the drop pool and the target water level, the water level difference opening adjustment amount of the bypass valve is calculated using a PID control algorithm, and the water level difference opening adjustment amount is superimposed with the reference opening adjustment amount specified in the reference control logic of the bypass valve, thereby generating the control command for the final opening adjustment amount of the bypass valve.

[0020] In step (1), the output power of the tailwater power generation system is also monitored in real time. When the output power is lower than the preset power threshold, steps (2) and (3) are skipped, and a control command to completely close the bypass valve is directly generated.

[0021] In step (1), when the tailrace power generation system receives a shutdown signal, steps (2) and (3) are skipped, and a control command to fully open the bypass valve is directly generated.

[0022] A coordinated control system for a wastewater treatment plant effluent power generation system is provided, used to execute the coordinated control method described above. The system includes a monitoring module, a signal acquisition module, a decision control module, and an execution module. The monitoring module monitors the operating parameters of the effluent power generation system. The signal acquisition module acquires the operating quantity signals of the upstream wastewater treatment plant's booster pumps. The decision control module receives the operating parameters and the operating quantity signals of the booster pumps, and calls a matching control strategy from a pre-set strategy library based on the total effluent volume, and generates a control command to adjust the opening of the bypass valve based on the deviation between the drop tank water level and the target water level. The execution module receives the control command and executes the bypass valve operation.

[0023] The monitoring module is also used to monitor the opening signal of the bypass valve. The opening of the bypass valve is measured by an opening detection device, which includes a detection controller and a sensor. The sensor is installed on the edge of the valve plate of the bypass valve. The sensor is used to detect the rotation angle of the valve plate and output a signal. The detection controller is used to receive the sensor signal and convert the angle change of the valve plate into a rotation opening signal.

[0024] This embodiment takes a tailrace hydroelectric power station as an example, and its main hardware includes: Water level sensor: Installed on the side wall of the drop pool, used to measure the water level of the drop pool in real time; Power transmitter: installed on the generator outlet bus, used to monitor the active power of the generator set in real time; Valve position sensor: It adopts a multi-turn absolute encoder angle rotation RS485+4~20mA miniature CAN waterproof displacement sensor and PLC controller (detection controller). By using the round edge detection method, it avoids the transmission clearance error caused by valve shaft detection, which is more accurate and more reliable. Signal acquisition module: reads the current water level of the drop tank through the water level sensor; reads the current output power of the generator through the power transmitter; reads the current opening degree of the bypass valve through the valve position sensor; and obtains the number of operating lift pumps from the sewage treatment plant through the communication network. Decision control module: Based on the acquired number of booster pumps N, it maps them to discrete operating conditions; based on the identified conditions, it calls the corresponding bypass valve reference control logic; based on the water level deviation, it calculates the bypass valve opening adjustment value, combines it with the basic opening, obtains the final opening, and generates instructions; Execution module: Controls the operation of the bypass valve according to instructions.

[0025] Based on historical operating data of the power station and analysis of the inlet lifting efficiency of the wastewater treatment plant, the optimal economic water level is 18 meters. (1) When one or two booster pumps are running: the bypass valve is fully closed and the unit is operating under optimal water level conditions; (2) When three booster pumps are operating: the bypass valve is fully closed, and the unit operates under optimal water level conditions; however, when the water level exceeds 20 meters, the bypass valve is opened to 5%; (3) When four booster pumps are running: after a 12-minute delay, open the bypass valve to 15% and the unit will operate under optimal water level conditions; when the water level exceeds 20 meters, open the bypass valve to 18%.

[0026] (4) When the operation is changed from four lift pumps to three lift pumps: the bypass valve is closed to 0% after a 15-minute delay, and the unit operates under the optimal water level condition.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described with reference to preferred embodiments, those skilled in the art should understand that various changes in form and detail can be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for coordinated control of a wastewater treatment plant effluent power generation system, characterized in that: Includes the following steps: (1) Monitor the water level of the drop pool in the tailwater power generation system in real time and obtain the number of operating pumps of the upstream sewage treatment plant. The pumps are used to increase the influent of the sewage treatment plant, and their number of operation determines the total amount of tailwater flowing into the tailwater power generation system. (2) Based on the number of pumps in operation, identify the total amount of tailwater currently flowing into the tailwater power generation system, and call the control strategy that matches the total amount of tailwater currently flowing into the system from the preset strategy library. The control strategy includes the bypass valve reference control logic corresponding to different total amounts of tailwater. (3) Based on the deviation between the water level of the drop pool and the target water level, and combined with the bypass valve reference control logic in the control strategy called, a control command to adjust the opening of the bypass valve is generated to maintain the stability of the drop pool at the target water level.

2. The coordinated control method for a wastewater treatment plant effluent power generation system according to claim 1, characterized in that: In step (2), the total amount of tailwater flowing in is identified by mapping the number of operations of the booster pump to multiple discretized operating conditions.

3. The coordinated control method for a wastewater treatment plant effluent power generation system according to claim 1, characterized in that: In step (2), the bypass valve reference control logic includes at least one of the following: (a) Determine the reference opening degree of the bypass valve based on the total inflow tailwater volume; (b) Set the water level threshold for triggering the bypass valve opening adjustment based on the total inflow tailwater volume; (c) Based on the change in the total inflow tailwater, control the delay parameter for the change in the opening of the bypass valve.

4. The coordinated control method for a wastewater treatment plant effluent power generation system according to claim 1, characterized in that: In step (3), the step of generating the control command for adjusting the opening of the bypass valve includes: based on the deviation between the water level of the drop pool and the target water level, the water level difference opening adjustment amount of the bypass valve is calculated using a PID control algorithm, and the water level difference opening adjustment amount is superimposed with the reference opening adjustment amount specified in the reference control logic of the bypass valve, thereby generating the control command for the final opening adjustment amount of the bypass valve.

5. The coordinated control method for a wastewater treatment plant effluent power generation system according to claim 1, characterized in that: In step (1), the output power of the tailwater power generation system is also monitored in real time. When the output power is lower than the preset power threshold, steps (2) and (3) are skipped, and a control command to completely close the bypass valve is directly generated.

6. The coordinated control method for a wastewater treatment plant effluent power generation system according to claim 1, characterized in that: In step (1), when the tailrace power generation system receives a shutdown signal, steps (2) and (3) are skipped, and a control command to fully open the bypass valve is directly generated.

7. A coordinated control system for a wastewater treatment plant effluent power generation system, characterized in that: The system, used to execute the coordinated control method as described in any one of claims 1 to 6, includes a monitoring module, a signal acquisition module, a decision control module, and an execution module; wherein the monitoring module is used to monitor the operating parameters of the tailwater power generation system; the signal acquisition module is used to acquire the operating quantity signal of the upstream sewage treatment plant's booster pumps; the decision control module is used to receive the operating parameters and the operating quantity signal of the booster pumps, and to call the control strategy matching the preset strategy library according to the total tailwater volume, and to generate a control command to adjust the opening of the bypass valve based on the deviation between the drop pool water level and the target water level; the execution module is used to receive the control command and execute the bypass valve operation.

8. The coordinated control system for the wastewater treatment plant effluent power generation system according to claim 7, characterized in that: The monitoring module is also used to monitor the opening signal of the bypass valve. The opening of the bypass valve is measured by an opening detection device, which includes a detection controller and a sensor. The sensor is installed on the edge of the valve plate of the bypass valve. The sensor is used to detect the rotation angle of the valve plate and output a signal. The detection controller is used to receive the sensor signal and convert the angle change of the valve plate into a rotation opening signal.