Hydropower station drainage system control method based on PID algorithm

Abstract

The invention discloses a hydropower station drainage system control method based on a PID algorithm, and the method comprises the steps: testing a drainage pump, and constructing a characteristic curve based on the power and drainage rate of the drainage pump; calculating the water level increasing rate of the water-collecting well; judging whether the pump is started or not at present, and if not, initializing pump starting based on the water level increasing rate; calculating the given power of the drainage pump based on the water level increasing rate and a PID algorithm; adjusting drainage pump power and executing circulation; the method solves the problems that in the prior art, due to extensive drainage control logic of a hydropower station, equipment is started and stopped frequently, a large amount of water leakage cannot be handled, and the equipment is damaged easily, and has the advantages that the water pumping rate of the drainage pump can be accurately adjusted and controlled through the PID algorithm, the water level dynamic balance of the water collecting well is achieved, and the risk that a plant is flooded is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of water discharge control of hydropower stations, and in particular relates to a water discharge system control method of a hydropower station based on a PID algorithm. Background Art

[0002] The drainage system is an important auxiliary control system of a hydropower station. Its main function is to remove all kinds of seepage, maintenance drainage and domestic water collected in the water collection well. When the water level in the water collection well reaches the set threshold, the drainage pump is started to pump out the water in the water collection well and discharge it to the tail water downstream of the power station. At present, the common drainage control system consists of a PLC controller, a water level sensor, a float switch, a soft starter, a lubricating water system, a three-phase drainage pump, etc. By manually setting the start and stop water levels of the pump, the PLC and the float switch control the start and stop of the motor. When the water leakage of the power station is large, the drainage pump is frequently started and stopped, which can easily cause the lubricating water system, the soft starter and the drainage pump body to fail, causing difficulties in operation and maintenance. In addition, if repairs are not carried out in time, a malicious incident of flooding the plant will occur, resulting in abnormal shutdown of the unit, threatening the stability of the power grid system and causing serious economic losses. Therefore, it is necessary to design a hydropower station drainage system control method based on the PID algorithm to solve the above problems. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a control method for the drainage system of a hydropower station based on a PID algorithm, which is used to solve the problem that the drainage control logic of the hydropower station in the prior art is extensive, resulting in frequent start and stop of the equipment, and unable to cope with the situation of large-scale water leakage, which is very likely to cause equipment damage. The method has the characteristics of accurately adjusting and controlling the pumping rate of the drainage pump through the PID algorithm to achieve dynamic balance of the water level in the collection well and reduce the risk of flooding the plant.

[0004] In order to achieve the above technical effects, the technical solution adopted by the present invention is: A method for controlling a drainage system of a hydropower station based on a PID algorithm comprises the following steps: S1, test the drainage pump and construct a characteristic curve based on the drainage pump power and drainage rate; S2, calculate the water level growth rate of the water collection well; S3, determine whether the pump is currently started. If the pump is not started, initialize the pump based on the water level growth rate; if the pump is started, enter S4; S4, calculating the given power of the drainage pump based on the water level growth rate and PID algorithm; S5, adjust the drainage pump power and enter S2 to execute the cycle.

[0005] Preferably, in step S1, constructing a characteristic curve based on drainage pump power and drainage rate includes: S11, build a simulation test environment, including 4-20mA current transmitter, power supply, drainage pump, inverter and small water collection tank; S12, the volume is V1m 3 Fill the small water collection tank with water; set the current value sent by the 4-20mA current transmitter to I1, calculate the current power of the drainage pump to P1, the time it takes to empty the small water collection tank to t1, and calculate the drainage rate R1=V1 / t1; S13, repeat S12, set different sending current value to I n , with a resolution of 0.1mA, so as to obtain the characteristic set of drainage pump power and drainage rate, and construct the characteristic curve of drainage pump power and drainage rate based on this set and fitting function.

[0006] Preferably, in step S2, calculating the water level growth rate of the water collection well includes: S21, the hydropower station drainage system controller collects water level analog data h through the water level sensor according to the period T; S22, calculate the current water level rising rate as L t =(h t -h t-T ) / T; where h t is the water level data collected at the current moment, h t-T is the water level data collected in the previous cycle, L t The unit is m / s; S23, calculate the sliding average value of the water level rise rate L_smooth t As the final water level rise rate; specifically, the controller stores the current water level rise rate and the water level rise rates of the previous n-1 (n≥1) cycles, forming a queue containing n water level rise rate values, and calculates the queue average as a sliding average; the larger the n value, the more it can avoid the occasional collection value jump of the water level sensor causing the calculated rise rate value to jump.

[0007] Preferably, step S3 includes: S31, the controller determines whether the pump has been started by collecting the feedback signal of the drainage pump. If the feedback signal value is 1, it means that the pump has been started, and if it is 0, it means that the pump has not been started; S32, when the controller determines that the pump is currently started, it enters process S4; S33, when the controller determines that the pump is not currently started, the pump start process is performed, specifically: The controller uses the output DO module and the time relay to put the lubricating water system into the pump for lubrication. When the time relay loses its magnetism, that is, when the preset time relay delay time is reached, the lubricating water input process ends. The controller outputs a power setting value to the inverter through the analog output AO module. The power is given based on the characteristic curve of the drainage pump power and drainage rate. The calculation method is: The current water level rise rate is L_smooth t , calculate the water volume growth rate as R t =L_smooth t ×S col , where S col is the cross-sectional area at the bottom of the water collection well, based on the water volume growth rate R t The drainage pump power initialization given value P is determined by the characteristic curve of drainage pump power and drainage rate init , drainage pump power initialization given value P init R is the water volume growth rate t The drainage pump power corresponding to the characteristic curve when the drainage rate is equal to that of the drainage pump; The controller excites the drainage system contactor through the output DO module and the intermediate relay, and the drainage pump starts.

[0008] Preferably, in step S4, calculating the given power of the drainage pump based on the water level growth rate and the PID algorithm includes: S41, the controller is based on the sliding average value L_smooth of the current water level rise rate t Calculate the water volume growth rate as R t =L_smooth t ×S col , where S col is the cross-sectional area at the bottom of the water collection well; based on the water volume growth rate R t The characteristic curve of drainage pump power and drainage rate determines the current given power P of the drainage pump given , which is the characteristic curve of drainage pump power and drainage rate when the drainage rate value is equal to the water volume growth rate R t Corresponding drainage pump power; S42, the current given power P of the drainage pump given Input PID model and calculate the regulating power P pid : First, the drainage pump current given power P given and the power P fed back by the drainage pump real Calculate the power to be adjusted ΔP, the formula is ΔP=P given -P real ; To avoid frequent power adjustment of the drainage pump, set the power dead zone value P db , calculate the effective power to be adjusted ΔP m , the formula is: ; The power to be adjusted by the effect ΔP mCalculate the regulation power P pid , the formula is: ; In the formula , , They are the coefficients of proportional, integral and differential regulation respectively.

[0009] Preferably, in step S5, adjusting the drain pump power and entering S2 to execute the cycle includes: S51, the controller adjusts the power P pid Control the output current I from the AO module to the inverter; I=P pid / (P max -P min )×20+4; where P max is the upper limit of the inverter power, P max is the lower limit of the inverter power, the unit of I is mA; S52, the inverter controls the current value of the drainage pump and adjusts the drainage pump power to the adjustment power P pid value; S53, enter step S2, modify the calculation formula of water level rise rate in S2 to L t =(h t -h t-T ) / T+L t-T ; L t-T is the water level rise rate in the previous cycle.

[0010] The beneficial effects of the present invention are as follows: The present invention can reduce the problem of easy damage to the equipment caused by frequent start and stop of the drainage pump. By using this method, the drainage pump can be put into operation for a long time. The pumping rate of the drainage pump can be accurately adjusted and controlled through the PID algorithm to achieve dynamic balance of the water level in the collection well and reduce the risk of flooding of the factory building. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a flowchart of this application; Figure 2 It is a schematic diagram of the drainage pump test environment of the present application; Figure 3 It is a schematic diagram of the pid algorithm flow in the embodiment of the present application. DETAILED DESCRIPTION

[0012] Embodiment 1: like Figure 1 As shown, a method for controlling a drainage system of a hydropower station based on a PID algorithm comprises the following steps: S1, test the drainage pump and construct a characteristic curve based on the drainage pump power and drainage rate; S2, calculate the water level growth rate of the water collection well; S3, determine whether the pump is currently started. If the pump is not started, initialize the pump based on the water level growth rate; if the pump is started, enter S4; S4, calculating the given power of the drainage pump based on the water level growth rate and PID algorithm; S5, adjust the drainage pump power and enter S2 to execute the cycle.

[0013] like Figure 2 As shown, in step S1, constructing a characteristic curve based on drainage pump power and drainage rate includes: S11, build a simulation test environment, including 4-20mA current transmitter, power supply, drainage pump, inverter and small water collection tank; S12, the volume is V1m 3 Fill the small water collection tank with water; set the current value sent by the 4-20mA current transmitter to I1, calculate the current power of the drainage pump to P1, the time it takes to empty the small water collection tank to t1, and calculate the drainage rate R1=V1 / t1; S13, repeat S12, set different sending current value to I n , with a resolution of 0.1mA, so as to obtain the characteristic set of drainage pump power and drainage rate, and construct the characteristic curve of drainage pump power and drainage rate based on this set and fitting function.

[0014] Preferably, in step S2, calculating the water level growth rate of the water collection well includes: S21, the hydropower station drainage system controller collects water level analog data h through the water level sensor according to the period T; S22, calculate the current water level rising rate as L t =(h t -h t-T ) / T; where h t is the water level data collected at the current moment, h t-T is the water level data collected in the previous cycle, L t The unit is m / s; S23, calculate the sliding average value of the water level rise rate L_smooth t As the final water level rise rate; specifically, the controller stores the current water level rise rate and the water level rise rates of the previous n-1 (n≥1) cycles, forming a queue containing n water level rise rate values, and calculates the queue average as a sliding average; the larger the n value, the more it can avoid the occasional collection value jump of the water level sensor causing the calculated rise rate value to jump.

[0015] Preferably, step S3 includes: S31, the controller determines whether the pump has been started by collecting the feedback signal of the drainage pump. If the feedback signal value is 1, it means that the pump has been started, and if it is 0, it means that the pump has not been started; S32, when the controller determines that the pump is currently started, it enters process S4; S33, when the controller determines that the pump is not currently started, the pump start process is performed, specifically: The controller uses the output DO module and the time relay to put the lubricating water system into the pump for lubrication. When the time relay loses its magnetism, that is, when the preset time relay delay time is reached, the lubricating water input process ends. The controller outputs a power setting value to the inverter through the analog output AO module. The power is given based on the characteristic curve of the drainage pump power and drainage rate. The calculation method is: The current water level rise rate is L_smooth t , calculate the water volume growth rate as R t =L_smooth t ×S col , where S col is the cross-sectional area at the bottom of the water collection well, based on the water volume growth rate R t The drainage pump power initialization given value P is determined by the characteristic curve of drainage pump power and drainage rate init , drainage pump power initialization given value P init R is the water volume growth rate t The drainage pump power corresponding to the characteristic curve when the drainage rate is equal to that of the drainage pump; The controller excites the drainage system contactor through the output DO module and the intermediate relay, and the drainage pump starts.

[0016] Embodiment 2: like Figure 3 As shown, in step S4, calculating the given power of the drainage pump based on the water level growth rate and the PID algorithm includes: S41, the controller is based on the sliding average value L_smooth of the current water level rise rate t Calculate the water volume growth rate as R t =L_smooth t ×S col , where S col is the cross-sectional area at the bottom of the water collection well; based on the water volume growth rate R t The characteristic curve of drainage pump power and drainage rate determines the current given power P of the drainage pump given , which is the characteristic curve of drainage pump power and drainage rate when the drainage rate value is equal to the water volume growth rate R t Corresponding drainage pump power; S42, the current given power P of the drainage pump givenInput PID model and calculate the regulating power P pid : First, the drainage pump current given power P given and the power P fed back by the drainage pump real Calculate the power to be adjusted ΔP, the formula is ΔP=P given -P real ; To avoid frequent power adjustment of the drainage pump, set the power dead zone value P db , calculate the effective power to be adjusted ΔP m , the formula is: ; The power to be adjusted by the effect ΔP m Calculate the regulation power P pid , the formula is: ; In the formula , , They are the coefficients of proportional, integral and differential regulation respectively.

[0017] Preferably, in step S5, adjusting the drain pump power and entering S2 to execute the cycle includes: S51, the controller adjusts the power P pid Control the output current I from the AO module to the inverter; I=P pid / (P max -P min )×20+4; where P max is the upper limit of the inverter power, P max is the lower limit of the inverter power, the unit of I is mA; S52, the inverter controls the current value of the drainage pump and adjusts the drainage pump power to the adjustment power P pid value; S53, enter step S2, modify the calculation formula of water level rise rate in S2 to L t =(h t -h t-T ) / T+L t-T ; L t-T is the water level rise rate in the previous cycle.

Claims

1. A method for controlling a drainage system of a hydropower station based on a PID algorithm, characterized in that: The following steps are involved: S1, test the drainage pump and construct a characteristic curve based on the drainage pump power and drainage rate; S2, calculate the water level growth rate of the water collection well; S3, determining whether the pump is currently started, and if not, initializing the pump based on the water level growth rate; If the pump has been started, enter S4; S4, calculating the given power of the drainage pump based on the water level growth rate and PID algorithm; S5, adjust the drainage pump power and enter S2 to execute the cycle.

2. A method for controlling a drainage system of a hydropower station based on a PID algorithm according to claim 1, characterized in that: In step S1, constructing a characteristic curve based on drainage pump power and drainage rate includes: S11, build a simulation test environment, including 4-20mA current transmitter, power supply, drainage pump, inverter and small water collection tank; S12, the volume is V1m 3 Fill the small water collection tank with water; set the current value sent by the 4-20mA current transmitter to I1, calculate the current power of the drainage pump to P1, the time it takes to empty the small water collection tank to t1, and calculate the drainage rate R1=V1 / t1; S13, repeat S12, set different sending current value to I n , with a resolution of 0.1mA, so as to obtain the characteristic set of drainage pump power and drainage rate, and construct the characteristic curve of drainage pump power and drainage rate based on this set and fitting function.

3. The method for controlling a drainage system of a hydropower station based on a PID algorithm according to claim 1, characterized in that: In step S2, calculating the water level growth rate of the water collection well includes: S21, the hydropower station drainage system controller collects water level analog data h through the water level sensor according to the period T; S22, calculate the current water level rising rate as L t =(h t -h t-T ) / T; where h t is the water level data collected at the current moment, h t-T is the water level data collected in the previous cycle, L t The unit is m / s; S23, calculate the sliding average value of the water level rise rate L_smooth t As the final water level rise rate; specifically, the controller stores the current water level rise rate and the water level rise rates of the previous n-1 (n≥1) cycles, forming a queue containing n water level rise rate values, and calculates the queue average as a sliding average; the larger the n value, the more it can avoid the occasional collection value jump of the water level sensor causing the calculated rise rate value to jump.

4. The method for controlling a drainage system of a hydropower station based on a PID algorithm according to claim 1, characterized in that: Step S3 includes: S31, the controller determines whether the pump has been started by collecting the feedback signal of the drainage pump. If the feedback signal value is 1, it means that the pump has been started, and if it is 0, it means that the pump has not been started; S32, when the controller determines that the pump is currently started, it enters process S4; S33, when the controller determines that the pump is not currently started, the pump start process is performed, specifically: The controller uses the output DO module and the time relay to put the lubricating water system into the pump for lubrication. When the time relay loses its magnetism, that is, when the preset time relay delay time is reached, the lubricating water input process ends. The controller outputs a power setting value to the inverter through the analog output AO module. The power is given based on the characteristic curve of the drainage pump power and drainage rate. The calculation method is: The current water level rise rate is L_smooth t , calculate the water volume growth rate as R t =L_smooth t ×S col , where S col is the cross-sectional area at the bottom of the water collection well, based on the water volume growth rate R t The drainage pump power initialization given value P is determined by the characteristic curve of drainage pump power and drainage rate init , drainage pump power initialization given value P init R is the water volume growth rate t The drainage pump power corresponding to the characteristic curve when the drainage rate is equal to that of the drainage pump; The controller excites the drainage system contactor through the output DO module and the intermediate relay, and the drainage pump starts.

5. A method for controlling a drainage system of a hydropower station based on a PID algorithm according to claim 4, characterized in that: In step S4, calculating the given power of the drainage pump based on the water level growth rate and the PID algorithm includes: S41, the controller is based on the sliding average value L_smooth of the current water level rise rate t Calculate the water volume growth rate as R t =L_smooth t ×S col , where S col is the cross-sectional area at the bottom of the water collection well; based on the water volume growth rate R t The characteristic curve of drainage pump power and drainage rate determines the current given power P of the drainage pump given , which is the characteristic curve of drainage pump power and drainage rate when the drainage rate value is equal to the water volume growth rate R t Corresponding drainage pump power; S42, the current given power P of the drainage pump given Input PID model and calculate the regulating power P pid : First, the drainage pump current given power P given and the power P fed back by the drainage pump real Calculate the power to be adjusted ΔP, the formula is ΔP=P given -P real ; To avoid frequent power adjustment of the drainage pump, set the power dead zone value P db , calculate the effective power to be adjusted ΔP m , the formula is: ； The power to be adjusted by the effect ΔP m Calculate the regulation power P pid , the formula is: ； In the formula , , They are the coefficients of proportional, integral and differential regulation respectively.

6. A method for controlling a drainage system of a hydropower station based on a PID algorithm according to claim 1, characterized in that: In step S5, adjusting the drain pump power and entering S2 to execute the cycle includes: S51, the controller adjusts the power P pid Control the output current I from the AO module to the inverter; I=P pid / (P max -P min )×20+4; where P max is the upper limit of the inverter power, P max is the lower limit of the inverter power, the unit of I is mA; S52, the inverter controls the current value of the drainage pump and adjusts the drainage pump power to the adjustment power P pid value; S53, enter step S2, modify the calculation formula of water level rise rate in S2 to L t =(h t -h t-T ) / T+L t-T ; L t-T is the water level rise rate in the previous cycle.

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