CN110764481A - Distributed redundant constant-pressure water supply control system - Google Patents
Distributed redundant constant-pressure water supply control system Download PDFInfo
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Abstract
The invention relates to a distributed redundant control system which dynamically adjusts the rotating speed of a pump based on the pressure, flow, temperature and other variables of fluid to achieve a desired control target. The product consists of 1 central management coordination unit and n mutually independent and redundant distributed control units, and each unit is in full-network information transmission and modular design. The central management coordination unit is only responsible for managing the coordination control unit, and the control right is handed over to each control unit. The central management coordination unit can be cascaded with the network segment and the cross-network segment. Pressure maintaining standby based on a multivariable weight algorithm, and the system does not do useless work due to dynamic flow compensation. The system has the characteristics of high reliability, sustainability, distributed operation, strong expansibility and energy conservation, solves the defects of poor reliability and shutdown of maintenance equipment in the traditional centralized control mode, and solves the difficult problems of low water supply continuity and small scale in the industry. The current industry after-sale service mode is changed, and the after-sale cost is greatly reduced.
Description
Technical Field
The invention relates to a constant-pressure water supply control system, in particular to a high-reliability, online maintenance and energy-saving constant-pressure water supply control system.
Background
Basic concept in constant pressure water supply control system
The Sensor is a pipeline pressure detecting instrument which is divided into a digital quantity type and an analog quantity type and is a signal acquisition element of a control system.
PLC (programmable controller): the control system controls the core and has the functions of signal acquisition, operation processing and output of the operation processing result to the execution element.
Driver (variable frequency drive): the pump set is a terminal execution element of a control system and is driven to operate by electric energy.
HMI (human machine interface): and the control process is visualized through a man-machine interaction touch screen.
The constant-pressure water supply control systems in the current market are mainly divided into the following three categories
Class I: sensor, 1 PLC, 1 Driver, HMI, and so on. Commonly known as "one drags more". And the PLC (programmable logic controller) is used as a centralized control unit, and forms an execution task to be transmitted to the actuator after the signals collected by the sensor and the control requirements are combined for operation processing. The Driver (frequency conversion Driver) is used as an actuator of the system to drive the pump motor to run, the pump driven by the Driver is a system speed regulating pump, when the rotating speed of the speed regulating pump reaches a speed regulating limit, the power frequency operation is started, then the rotating speed of the speed regulating pump is continuously regulated, and the purpose of constant-pressure water supply is achieved.
And II: sensor, 1 PLC, multiple drivers, HMI, and so on. Commonly known as "one drags one". The number of 1 Driver (variable frequency Driver) in the class I is changed into a plurality. The speed regulating pumps are changed from 1 to a plurality of pumps, and all the pumps realize soft start.
Class III: sensor, 2 PLC, several drivers, HMI, and other sensors. The method is commonly called 'redundant one-to-one'. Change 1 PLC (programmable controller) in class II to 2 or use redundant PLC (i.e. CPU module redundancy of PLC).
The limitations and disadvantages of class i, class ii, and class iii are as follows:
1. low reliability
Let A, B, C … N be the elements of the control system, the corresponding probability of normal operation is P (A), P (B), P (C) … P (N), and the corresponding probability of abnormal operation is P (a), P (b), P (c) … P (N).
Since "normal operation" and "abnormal operation" constitute contradictory events,
therefore, it is not only easy to use
P(a)=1- P(A)、
P(b)=1- P(B)、
P(c)=1- P(C)
…
P(n)=1- P(N)。
And each of P (A), P (B), P (C) … P (N) is < 1. For a redundant relationship where there are a plurality of identical components, which are redundant to each other, they can be regarded as a group, denoted as a component X, and the number thereof is m for the whole system. Its normal operation probability p (x) =1- [ p (x)]m(wherein P (x) is the probability of abnormal operation of a certain element in the element group)
Class i control system: the whole set of control system work task is completed by the mutual cooperation of all the elements in steps, namely the completion of the work task is realized based on the fault-free operation of each element at the same time, so the normal operation probability P (I) = P (A) · P (B) · P (C)) … P (N))
Class ii control system: assuming that the frequency converter element group is B and the number of the frequency converter element groups is m, the probability P (B) =1- [ P (B) that the frequency converter group normally operates]m. Similarly, the normal operation probability P (II) = P (A) · {1- [ P (b)]m}·P(C)…P(N)
Class iii control system: let the controller element group be a. The number of the controller element groups is 2, the probability P (A) =1- [ P (a)]2. Assuming that the frequency converter element group is B and the number of the frequency converter element groups is m, the probability P (B) =1- [ P (B) that the frequency converter group normally operates]m. Similarly, the normal operation probability P (III class) = {1- [ P (a)]2}·{1-[P(b)]mP (c) … p (n). The two redundant controllers are used as centralized control units, and the working mechanism is that one controller is automatically switched to the standby controller in a failure mode. The system is designed redundantly on the surface, but the problem is how to diagnose the controller fault, because the structure of the controller is complex and consists of a plurality of components, and when any one component is in fault, the controller cannot work normally, so that the faults are various, such as processor 'heartbeat stop', communication faults, input and output interface faults and the like, and the task of detecting each fault is almost impossible to complete. So it is usually to detect thereinOne or more of the faults are used as conditions for switching to the redundant controller, and when a plurality of faults occur, the conditions are not used for switching to the redundant controller, that is, when a plurality of faults occur, the system cannot be switched to the standby controller, so that the probability of equipment halt is high. So P (III) = {1- [ P (a)]2}·{1-[P(b)]mAnd (C) … P (N) is the maximum probability value of the normal operation of the control system, and the actual normal operation probability is smaller than the value.
The multiplication factors in the calculation formulas of the normal operation probabilities of the I type, the II type and the III type are all smaller than 1, and the probability P value is decreased with the increase of the number of the multiplication factors. I.e. the more system components or the larger the pump package scale-up, the less stable the system. Even if the redundancy design is added in class II and class III, the reliability of a local element group is only improved, the reliability of other elements is not improved, and the reliability of the whole set of control system as a unified whole is not substantially improved. As can be seen from the normal operation probability calculation formula, the formula has a plurality of multiplication factors, 1 or 2 multiplication factor values are added, and the influence on the whole formula value P is small. From the normal operation probability calculation formula alone, we can increase each multiplicative factor value, thereby increasing the total value P of the calculation formula. I.e. each element in the whole set of system is designed redundantly for the purpose of increasing reliability, but this is difficult to achieve in practice, and even if it is achieved, the system will add many elements for detecting and switching the faulty element, the cost will be very high, and the system will become cumbersome. Assuming that now, the cost is not counted, each component of the whole set of system is designed redundantly, the reliability of each component group of the whole set of system is indeed improved, but the number of components in the whole set of system is also increased, and the number of multiplication factors in the formula is also increased. This approach increases both the individual multiplier values, which are always less than 1, and the number of multipliers. Such a bulky redundant design would adversely decrease the stability of the system due to the increased number of components. Therefore, the water supply industry needs a brand new and revolutionary design concept to improve the stability of the control system.
The common feature of the I, II and III is centralized control, that is, PLC (programmable logic controller) is used as a control core, and all the others are developed around the PLC. Centralized control is recognized as unreliable. If the central control unit fails, the whole system is broken down, i.e. "all losses". Besides, another disadvantage of centralized control is that on-line maintenance cannot be performed, i.e. during maintenance, the equipment must be stopped before maintenance, which affects the continuity of water supply of the equipment.
2. The cost after sale is high. The after-sales cost includes the cost of human and material resources. Due to the high demand on the water supply continuity by the end user, in order to ensure that the equipment can be restored to the water supply in time after a failure, it is common to arrange for a professional 365 x 24 hours to stay in the vicinity of the equipment and prepare a spare part. Because the equipment is numerous and distributed in different cities, water supply equipment manufacturers allocate a large amount of manpower and material resources to after-sale services of the equipment.
3. The expansion capability is not strong, and the large-scale water supply system cannot be competent. The expansion capability of the I type, the II type and the III type depends on physical resources of a PLC (programmable logic controller) control core unit, such as DI/DO, processor operation speed and memory resources, and the resources of a single PLC are precious and limited.
4. During the peak period of water consumption, the pressure at the tail end of the pipe network is insufficient. As the water flow increases, the pressure difference between the head (measurement point) and tail end of the pipe also increases. When the water consumption is large (water consumption peak period), even if the pressure of the water outlet of the pump set is kept constant, the water pressure of the user side is smaller than that of the user side when the water consumption is small (water consumption valley period), and at the moment, the constant-pressure water supply is not constant from the view of the user side.
The judgment of the pressure maintaining standby condition of the control system is not accurate. The current industry has a common practice that the operating frequency of the water pump is lower than the set pressure maintaining threshold frequency as a judgment condition, and as the PID operation is controlled to be close to the set value and the feedback value, the PID output value is basically unchanged, namely the operating frequency of the pump is also unchanged, so that the problem of inaccurate judgment of the pressure maintaining standby condition is caused. Or unable normal pressurize, or frequent pressurize, the former causes water pump cavity high temperature, the latter frequently stops the water pump, both have shortened water pump life and extravagant energy.
Disclosure of Invention
Aiming at the problems in the prior art in the industry, a solution of a distributed redundant constant-pressure water supply control system is provided, and the solution is a distributed redundant control system which dynamically adjusts the rotating speed of a pump based on the pressure, flow, temperature and other variables of fluid to achieve the expected control target.
1. Hardware composition: to express the quantitative relationship between the elements more clearly, the notation N (1. ltoreq. n.ltoreq.8, N. epsilon.N) is now quoted+）、m（n≤m≤3n,m∈N+). The product consists of 1 central management coordination unit, n independent distributed control units capable of running independently, m pumps, 2n digital quantity sensors and 2n analog quantity sensors, and the connection mode of each unit is Ethernet communication. The central management coordination unit and the distributed control unit are respectively arranged in the mechanical cabinet bodies with the modular structure, and 1+ n mechanical cabinet bodies are total. The mechanical cabinet body is designed in a modular structure, the appearance and the size of the mechanical cabinet body are the same in a similar power gradient group, other 5 surfaces can be spliced at will except for the surface with an operation knob and an indicator light, and the mechanical cabinet body can be selected according to the power and the number configuration of a pump group so as to adapt to application scenes of any size and scale.
2. The central management coordination unit mainly comprises a mechanical cabinet body with a modular structure, a touch screen, a state indicator lamp, an operation knob, a circuit breaker, a controller and a switching power supply. The system reserves an Ethernet interface, a serial interface, a digital IO interface and an analog IO interface, and is used for low-cost function upgrading in the future. The central management coordination unit is only responsible for management coordination and serves the distributed control units, and the control right is handed to each distributed control unit. The central management coordination unit takes the Ethernet (TCP/IP) as a communication carrier and is actively connected with the server of the distributed control unit by the identity of the client, and the same network segment, cross-network segment star or ring network topological structure is supported to be cascaded to form a large-scale water supply control system. The central management coordination unit is used as a client and actively connected with the remote cloud server, actively uploads the state information of the control system, downloads the configuration information of the cloud server, and realizes the remote monitoring function through a web browser, a mobile phone APP and a WeChat applet.
The central management coordination unit and the distributed control unit respectively generate heartbeat pulse marks and simultaneously mutually detect the heartbeat pulse marks of the other side so as to judge whether the other side is in an active state and whether the communication is normal. The real-time clock RTC of the central management coordination unit has two setting methods, one is actively connected with the NTP server, and the other is manually set time through a touch screen. The real-time clock RTC of the distributed control unit is synchronized with the real-time clock RTC of the central management coordination unit once every 24 hours or is synchronized once when the distributed control unit is online again after being disconnected with the central management coordination unit network. When the central management coordination unit detects that the heartbeat of the distributed control unit exists, the distributed control unit is in a remote control state, and no serious shutdown fault or alarm exists, the central management coordination unit brings the distributed control unit into a unified scheduling management camp to participate in system linkage. The method for acquiring the pressure value of the water inlet end of the control system comprises the steps of reading the pressure value of the water inlet end of each control unit, eliminating the analog quantity sensor value which has a fault, and finally taking the minimum value of all the values as the water inlet pressure value of the control system. The method for acquiring the pressure value of the water outlet end of the control system comprises the steps of firstly reading the pressure value of the water outlet end of each control unit, then eliminating the analog quantity sensor value which has failed, and then taking the maximum value as the pressure value of the water outlet of the control system when the difference value delta between the maximum value and the minimum value in all the values is less than 0.04MPa, and sending the value to each control unit as the common pressure feedback value P. And if the difference value delta between the maximum value and the minimum value in all the values is larger than or equal to 0.04MPa, taking the minimum value as the water outlet pressure value of the control system, generating an alarm message of overlarge display value difference of the water outlet end analog quantity sensor, and sending the alarm message to each control unit, wherein after each control unit receives the message, the display value of the water outlet end analog quantity sensor of the local pump set is used as a pressure feedback value P. When the central management coordination unit is in a starting state and detects that no serious fault or alarm occurs in the whole control system, if the feedback pressure value P is less than the set pressure value S and the load of the control unit is more than 98%, adding 1 control unit to operate; if the feedback pressure value P is approximately equal to the set pressure value S, balancing the load of the distributed control units (the number of the control units which are put into operation is more than or equal to 2); if the feedback pressure value P is larger than the set pressure value S and the load of the control unit is smaller than 10%, reducing 1 control unit to be put into operation.
The touch screen of the central management coordination unit visualizes the process state and parameter setting of the system, and human-computer interaction is realized. After the process parameters of each control unit are set on the touch screen, the process parameters are transmitted to the central management coordination unit through the Ethernet, and then are transmitted to each distributed control unit through the Ethernet by the central management coordination unit, and the state information transmission of each control unit is transmitted to the touch screen of the central management coordination unit along an opposite path. The main content on the touch screen comprises real-time state information, real-time fault/alarm, parameter setting, historical fault/alarm, system operation logs and historical pressure value information of a water inlet end and a water outlet end of the system of the whole control system.
3. The distributed control unit mainly comprises a mechanical cabinet body with a modular structure, a state indicator lamp, an operation knob, a circuit breaker, a controller, a switching power supply, a frequency converter, 2 digital quantity sensors and 2 analog quantity sensors. The controller supports the simultaneous input of analog quantity voltage (0-5V/0-10V) and current (4-20 mA/0-20 mA), and a voltage/current input signal software change-over switch is arranged on a touch screen of the central management coordination unit so as to adapt to two types of output signal analog quantity sensors. The controller and the frequency converter of the distributed control unit are in communication connection and exchange data in a field bus (such as a Modbus RTU) mode, the frequency, the current, the power, the torque and the like of real-time state data of the frequency converter are read, and the frequency converter is controlled to start and stop, the operation frequency is controlled, and fault reset is carried out. 1 distributed control unit supports 1-3 pumps. The water inlet and outlet ends of the pumps share a common main pipeline, which is respectively called a water inlet main pipe and a water outlet main pipe. 1 digital sensor, 1 analog sensor are respectively installed on pump business turn over water house steward, and when digital, the analog sensor of intake house steward detected that the pressure of intake water is low or digital, the analog sensor of delivery house steward detected that the pressure of delivery water is too high, this control unit made the processing of shutting down to output corresponding alarm message. When the digital quantity and analog quantity sensors of the water inlet main pipe detect that the water pressure of the water inlet is too high or the digital quantity and analog quantity sensors of the water outlet main pipe detect that the water pressure of the water outlet is too low, the control unit only outputs corresponding alarm messages. The distributed control unit is provided with a hardware local/remote operation switching function knob, and field workers can determine whether the control unit participates in system linkage or not, and whether other distributed control units operate or not is irrelevant to any operation of the control unit, so that online maintenance of equipment is realized. The distributed control unit is communicated with the central management coordination unit in real time, sends local state information, receives configuration information of the central management system unit, detects heartbeat flag bits in real time, detects low flag bits of pressure values of a system water outlet end in real time, and detects 1 flag bit of pressure values of the water outlet end of each control unit of the system, wherein the deviation of the pressure values of the water outlet end of each control unit of the system is more than or equal to 0.04MPa, the 3 flag bits occur randomly, the distributed control unit starts an autonomous operation mode immediately, the water outlet pressure value of a local pump set is used as a pressure feedback value at the moment, the common pressure feedback value is used as a pressure feedback value after all the 3 flag bits are reset, and then. And the distributed control unit performs PID operation by using the pressure feedback value and the pressure set value, and the operation result is sent to the frequency converter in a field bus communication mode. When the operation information sent by the central management coordination unit is received and the water pressure at the water inlet end and the water outlet end of the pump is normal and no serious fault or alarm exists, the motor of the frequency converter driving pump is started to operate at the speed calculated by PID. For the detailed flow of the control of the distributed control unit, please refer to fig. 5 in the specification, which is not described herein again.
4. And dynamically adjusting the flow compensation value based on the motor speed variable. For the clear expression of the flow compensation value, the symbolic meaning is defined as follows:
Pfpressure feedback value (real-time)
PaTarget pressure value (real time)
PbBasic pressure value (static state)
PcSingle pump maximum compensation pressure value (static state)
FiRunning frequency value (real time)
FbBasic frequency value (static), typically 25Hz
FmaxMaximum frequency value (static), typically 50Hz
PicSingle pump compensation pressure value (real time)
n: number of pumps running
Parameter Pb、Pc、Fb、FmaxIt needs to be set. Pb、PcRespectively according to the water supply height and the flow rate of the actual application scene. FbAccording to the actual pump head, the meaning of the pump head is that when the motor runs at the frequency, the actual pump head output by the pump is close to zero, FmaxIs the maximum operating frequency allowed for the pump motor. When the pump motor runs in real time at frequency Fi≤FbTime, target pressure value (real time) Pa= Pb(ii) a When the pump motor runs in real time at frequency Fi>Fb(if the pump is operating at power frequency, Fi50 Hz), target pressure value (real time) Pa= Pb+ n·PicIn which P isic= [Pc/ (Fmax－Fb)]·(Fi－Fb). From this, the target pressure value (real time) P can be seenaIs a dynamic curve, the rule of which is changed along with the change of water consumption. System with Pa、PfAfter PID operation, a pressure feedback value (real-time) P is obtainedfThe curve law is to follow the target pressure value (real-time) PaThe flow dynamic compensation function is realized.
5. And (4) keeping the pressure at a low flow rate for standby based on a multivariable weight algorithm. Four steps are required to achieve this function: 1. setting variable weight distribution parameters of a pump motor; 2. setting static parameters when the flow is zero; 3. calculating a real-time total evaluation percentage value; 4. the percentage threshold value, increments of dwell standby acknowledgement time are evaluated. The specific implementation method comprises the following steps:
motor variable weight assignment parameters set typical values: frequency Fw=40%, power Pw=30% torque Tw=20% current Cw= 10%. At zero flow, static parameters are setDetermining: firstly, making the system be in the running state of single pump, secondly slowly closing water outlet valve of pump group, the criterion of slowly closing valve is that the pressure value of water outlet is kept stable, after the valve is completely closed, recording that the frequency, power, torque and current value are respectively F0、P0、T0、C0. Calculating the real-time total evaluation percentage P: fi、Pi、Ti、CiRespectively expressed as real-time frequency, power, torque, current; pF、PP、PT、PCExpressed as real time frequency percentage, power percentage, torque percentage, current percentage, respectively. Real-time total assessment percentage formula P = PF+PP+PT+PCIn which P isF= [(Fw－1)/ F0]·Fi+1 (when P isF＜FwThen let PF=Fw)、PP=[(Pw－1)/ P0]·Pi+1 (when P isP＜PwThen let PP=Pw)、PT=[(Tw－1)/T0]·Ti+1 (when P isT＜TwThen let PT=Tw)、PC=[(Cw－1)/ C0]·Ci+1 (when P isC＜CwThen let PC=Cw). Evaluation of percentage threshold, incremental increase of dwell standby confirmation time: when the distributed control units operate autonomously or more than 2 control units participate in the linkage central management coordination unit to detect that only 1 pump operates, initializing the evaluation percentage threshold value Ps=10% (typical value), pressure-holding standby confirmation time value Ts=60s (typical value). When the real-time pressure feedback value is approximately equal to the real-time target pressure value Pa(the decision criterion is | Pf－PaLess than 0.01 MPa) and the real-time total evaluation percentage P is more than or equal to PsCoexisting and having a duration of not less than TsIn time, the system is stopped and pressure is maintained, and the standby duration T of pressure maintaining is comparediAnd T0(typically 60s) size. If Ti＜T0Then, for the evaluation percentage threshold value PsIncrease by 10% increaseThe steps are repeated until PsNo longer increasing after = 100%. When P is presentsIf not less than 100%, the waiting confirmation time value T is set for the pressure holdingsThe doubling treatment was carried out until it was equal to 8 hours and no longer doubled. If T appearsi≥T0Then, the evaluation percentage threshold value P is initializeds=10%, pressure-maintaining standby confirmation time value Ts=60s。
The distributed redundant constant-pressure water supply control system has the following advantages over the existing constant-pressure water supply systems in the market:
1. the reliability is high. Setting a central management coordination unit as X and each control unit as A, B, C … N; failure probabilities p (x) =0.1%, p (a) =1%, p (b) =1%, p (c) =1%, … p (n) = 1%. X only coordinates A, B, C … N work and does not participate in control, so when X fails, the probability P of shutdown of the whole equipment is not influenced, hardware and software of A, B, C … N are independent, namely A, B, C … N individual failure occurrence events are independent events. Overall plant outage probability P = P (a) P (b) P (c) … P (n) =1% × 1% >, 1% = (1/100)nProbability P Limit is (1/100)nAnd =0. Therefore, the distributed redundant constant-pressure water supply control system approaching 100% of reliability can be applied to scenes with life and property safety. Can replace gravity water supply modes such as a water tower with extremely high requirements on water supply continuity and the like. The industrial problem that the water supply equipment can continuously run for 365 x 24 hours is solved.
2. And the after-sale service mode is changed, so that the after-sale cost is greatly reduced. Even if the equipment fails, the water supply continuity is not affected. The equipment can be maintained on line and the fault fittings can be replaced without stopping the equipment.
3. The expansibility is strong, and the reliability can not be reduced along with the increase of the expansion scale. Can be used for large-scale and ultra-large-scale water supply systems.
4. The dynamic flow compensation function compensates for the pressure difference value increased at the head end and the tail end of the pipe network in the water consumption peak period, compensates for the reduction of the pressure at the tail end of the pipeline, and further improves the water consumption experience of users.
5. The low-flow pressure-maintaining standby function based on the multivariable weight algorithm accurately deduces whether the current water consumption is close to zero or not, and further determines whether the system enters a standby state or not. The problem of in the trade cause the pump cavity overheated and frequently pressurize the standby and cause the water pump frequently to open and stop the pain point because of the pump stifled water idle running that can not get into pressurize standby state in time or accurately is solved, prolonged water pump life and energy saving.
Drawings
FIG. 1: product appearance diagram of distributed redundancy control system (3 pumps)
FIG. 2: ring network topological structure network of 3 pump sets
FIG. 3: central management coordination unit control flow 1
S000 Central management coordination Unit Start
S100 generating heartbeat pulses
S200, clock synchronization, read state and write configuration of each control unit
S310:1# control unit heartbeat existence
S311:1# control unit remote status
S312 is the 1# control Unit Ready
Whether heartbeats exist in S320:2# control unit
S321:2# control unit remote state
S322 #2 # control unit is ready
S380 is that the heartbeat of the 8# control unit exists
S381 #8 # control unit remote state
S382 # 8 control Unit Ready
S400, calculating the linkage mark of each control unit participating in the system
FIG. 4: central management coordination unit control process 2 (continuation 1)
S510, taking the minimum value of the normal pressure values of the water inlet ends of the control units as a common water inlet pressure value
S520, the normal pressure value Pmax-Pmin = delta of the water outlet end of each control unit is not less than 0.04MPa
S610, taking the maximum value of the normal pressure values of the water outlet ends of the control units as a common water outlet pressure value
S620, taking the minimum value of the normal pressure values of the water outlet ends of the control units as a common water outlet pressure value
S700, is there serious fault or alarm
S800, start command is
S810, the feedback value P is not less than the set value S
S811 adding 1 control unit to operate
S812, comparing the feedback value P with the set value S and balancing the control unit load
S813 reducing 1 control unit operation
S900, the central management coordination unit ends
FIG. 5: distributed control unit control flow
S000 distributed control Unit Start
S100 local/remote control mode selection
S210 remote
S211, communicating with the central unit to obtain the heartbeat, the start-stop state, the running command and the shared pressure feedback value
S212, the central unit is in a starting state
S213, the heart beat of the central unit exists
S214, the pressure feedback difference value of each control unit is less than 0.04MPa
S215, if the common pressure feedback value of the central unit is too low
S216, the central unit sends a running message
S217, the control unit detects that the water pressure in and out is normal, serious faults exist and an alarm is given
S218, the distributed control unit starts the frequency converter
S220 local
S221, is locally started
S300, taking the water outlet pressure value of the local pump set of the distributed control unit as a pressure feedback value
S310, the central unit shares the pressure feedback value as the pressure feedback value
S320, performing PID operation on the pressure set value S and the pressure feedback value S of the distributed control unit
S330, communicating the frequency value of PID operation of the distributed control unit to the frequency converter
S400, the distributed control unit ends
FIG. 6: typical hardware architecture of distributed redundant constant-pressure water supply control system
Detailed Description
In order to more clearly illustrate the technical solution of the present invention, an exemplary embodiment in practical application is selected and fully described with reference to the accompanying drawings. It is to be understood that the described embodiment is only one embodiment of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The pressurizing pump group selected in the embodiment is a 3-pump distributed redundant control system, and the appearance is shown in figure 1.
1. Hardware composition: the distributed redundant control system consists of 1 central management coordination unit, 3 mutually independent distributed control units capable of running independently, 3 pumps, 6 digital quantity sensors and 6 analog quantity sensors. The water inlet and outlet end of each pump is respectively provided with 1 digital quantity sensor and 1 analog quantity sensor, please note that the water inlet and outlet end of each pump is not the water inlet and outlet main pipe of the pump group, and the information detected by the digital quantity sensor and the analog quantity sensor is only effective for the pump and is irrelevant to the other 2 pumps. The connection mode of the 3 distributed control units and the 1 central management coordination unit is ring topology structure ethernet communication, as shown in fig. 2. The central management coordination unit and the distributed control unit are respectively arranged in the mechanical cabinet bodies with the modular structures, and 4 mechanical cabinet bodies with the modular structures and the same appearance size are spliced and combined together, as shown in fig. 1.
2. The central management coordination unit mainly comprises a mechanical cabinet body with a modular structure, a touch screen, a state indicator lamp, an operation button, a circuit breaker, a controller and a switching power supply. The system reserves an Ethernet interface, a serial interface, a digital IO interface and an analog IO interface, and is used for low-cost function upgrading in the future. The central management coordination unit is only responsible for management coordination and serves the distributed control units, and the control right is handed to each distributed control unit. The central management coordination unit takes Ethernet (TCP/IP) as a communication carrier and actively connects with the server of the distributed control unit in the identity of the client. The central management coordination unit is used as a client and actively connected with a remote cloud server, actively uploads the state information of the system, downloads the configuration information of the cloud server, and realizes a remote monitoring function through a web browser, a mobile phone APP and a WeChat applet. The following is further described with reference to fig. 3 and 4:
step S000: and powering on and starting the central management coordination unit.
Step S100: the central management coordination unit and the distributed control unit respectively generate heartbeat pulse marks and simultaneously mutually detect the heartbeat pulse marks of the other side so as to judge whether the other side is in an active state and whether the communication is normal.
Step S200: the central management coordination unit and the distributed control unit synchronize real-time clocks. The real-time clock RTC of the central management coordination unit has two setting methods, one is actively connected with the NTP server, and the other is manually set time through a touch screen. The real-time clock RTC of the distributed control unit is synchronized with the real-time clock RTC of the central management coordination unit once every 24 hours or is synchronized once when the distributed control unit is online again after being disconnected with the central management coordination unit network. The central management coordination unit reads state information of the distributed control unit and writes configuration parameters, wherein the state information comprises diagnostic information of a system, water pressure values of a water inlet end and a water outlet end of a pump, a ready state, an operation state, a pressure maintaining standby state, a local/remote mode state, instantaneous current, instantaneous power, instantaneous frequency, instantaneous torque, accumulated energy consumption and accumulated operation time; the configuration parameters comprise diagnostic information confirmation of the system, water inlet and outlet end sensor parameters of the pump, a manual/automatic mode, a sub-water supply mode (namely a constant pressure mode, a self-defined curve mode and a flow dynamic compensation mode) in an automatic mode and a target pressure value.
Steps S300 to S382: the central management coordination unit detects whether heartbeats exist in each distributed control unit, whether the heartbeat is in a remote control state, whether a serious shutdown fault is caused or whether an alarm exists.
Step S400: and determining whether to incorporate the corresponding distributed control unit into a unified scheduling management array according to the detection results of the steps S300 to S382, and participating in system linkage.
Step S510: taking the minimum value of the normal pressure values (eliminating the analog sensor display values which have failed) of the water inlet ends of all the control units participating in system linkage as a common water inlet pressure value, wherein the common water inlet pressure value is taken as the water inlet pressure value of the whole distributed redundancy control system
Steps S520 to S620: the method for acquiring the pressure value of the water outlet end of the control system comprises the steps of firstly reading the pressure value of the water outlet end of each control unit, eliminating the analog quantity sensor value which has a fault, taking the maximum value as the pressure value of the water outlet of the control system when the difference value delta between the maximum value and the minimum value in all the values is less than 0.04MPa, and sending the value to each control unit as the common pressure feedback value P. And if the difference value delta between the maximum value and the minimum value in all the values is larger than or equal to 0.04MPa, taking the minimum value as the water outlet pressure value of the control system, simultaneously generating an alarm message of overlarge display value difference of the water outlet end analog quantity sensor, and sending the alarm message to each control unit, wherein after each control unit receives the message, the display value of the water outlet end analog quantity sensor of the local pump set is respectively used as a pressure feedback value P.
Steps S700 to S813: when the central management coordination unit is in a starting state and detects that no serious fault or alarm is generated in the whole control system, if the feedback pressure value P is less than the set pressure value S and the load of the control unit is more than 98 percent, adding 1 control unit to operate; if the feedback pressure value P is approximately equal to the set pressure value S, balancing the load of the distributed control units (the number of the control units which are put into operation is more than or equal to 2); if the feedback pressure value P is larger than the set pressure value S and the load of the control unit is smaller than 10%, reducing 1 control unit to be put into operation.
Step S900: after the single operation cycle of the central management coordination unit is finished, since the controller is a loop execution program, the system automatically jumps to step S100 to execute, and so the loop goes to ….
The touch screen of the central management coordination unit visualizes the process state and parameter setting of the system, and human-computer interaction is realized. After the process parameters of each control unit are set on the touch screen, the process parameters are transmitted to the central management coordination unit through the Ethernet, and then are transmitted to each distributed control unit through the Ethernet by the central management coordination unit, and the state information transmission of each control unit is transmitted to the touch screen of the central management coordination unit along an opposite path. The main content on the touch screen comprises real-time state information, real-time fault/alarm, parameter setting, historical fault/alarm, system operation logs and historical pressure value information of a water inlet end and a water outlet end of the system of the whole control system.
3. The distributed control unit mainly comprises a mechanical cabinet body with a modular structure, a state indicator lamp, an operation knob, a circuit breaker, a controller, a switching power supply, a frequency converter, 2 digital quantity sensors and 2 analog quantity sensors. The controller supports the simultaneous input of analog quantity voltage (0-5V/0-10V) and current (4-20 mA/0-20 mA), and a voltage/current input signal software change-over switch is arranged on a touch screen of the central management coordination unit so as to adapt to two types of output signal analog quantity sensors. The controller and the frequency converter of the distributed control unit are in communication connection and exchange data in a field bus (such as a Modbus RTU) mode, the frequency, the current, the power, the torque and the like of real-time state data of the frequency converter are read, and the frequency converter is controlled to start and stop, the operation frequency is controlled, and fault reset is carried out. Each distributed control unit of the embodiment has 1 pump and 3 pumps. The water inlet and outlet ends of the 3 pumps share a common main pipeline which is respectively called a water inlet main pipe and a water outlet main pipe. The single pump inlet and outlet water pipe is respectively provided with 1 digital sensor and 1 analog sensor, when the digital sensor and the analog sensor of the inlet water pipe detect that the water pressure of the inlet water is too low or the digital sensor and the analog sensor of the outlet water pipe detect that the water pressure of the outlet water is too high, the control unit stops the machine and outputs corresponding alarm information. When the digital quantity and analog quantity sensors of the water inlet pipe detect that the water pressure of the water inlet pipe is too high or the digital quantity and analog quantity sensors of the water outlet pipe detect that the water pressure of the water outlet pipe is too low, the control unit only outputs corresponding alarm information. The distributed control unit operates the switching function locally/remotely, and can manually decide whether the control unit participates in the system linkage on site, and whether other distributed control units operate or not is irrelevant to any operation of the control unit, so that online maintenance of equipment is realized. With reference to fig. 5, an example of selecting 1 of the 3 distributed control units (the other 2 distributed control units are the same as above) is further described as follows:
step S000: and powering on and starting the distributed control unit.
Step S100: the distributed control unit detects the "local/remote mode" hardware knob status.
Step S220: when the distributed control unit "local/remote mode" hardware knob is in local mode and the "start/stop" hardware knob is in start state, it jumps to step S217, otherwise, it stops local operation.
Step S211: when the distributed control unit 'local/remote mode' hardware knob is in a remote mode, the distributed control unit communicates with the central unit in real time to acquire a 'heartbeat flag bit', a start-stop state, an operation command and a shared pressure feedback value, sends local state information to the central management coordination unit, and receives configuration information of the central management coordination unit.
Steps S213 to S215 and steps S300 to S330: the heartbeat stop zone bit, the over-low zone bit of the pressure value at the water outlet end of the system and the deviation of the pressure value at the water outlet end of each control unit of the system are detected in real time, 1 zone bit of the 3 kinds of zone bits occurs randomly, the distributed control unit starts an autonomous operation mode immediately, the water outlet pressure value of a local pump set is used as a pressure feedback value at the moment, the shared pressure feedback value is used as a pressure feedback value after all the 3 kinds of zone bits are reset, and then the whole system is put into the system to participate in system linkage. And the distributed control unit performs PID operation by using the pressure feedback value and the pressure set value, and the operation result is sent to the frequency converter in a field bus communication mode.
Step S216: the distributed control unit receives the message that the central management coordination unit informs whether to run locally in real time.
Step S217: the distributed control unit detects whether the water pressure values of the water inlet end and the water outlet end of the local pump are normal in real time, wherein the normal means that the measured values of the digital quantity and the analog quantity sensor of the water inlet end are not smaller than the too-low threshold value of the water pressure of the water inlet, and the measured values of the digital quantity and the analog quantity sensor of the water outlet end are not larger than the too-high threshold value of the water pressure of the. The distributed control unit detects whether a local serious fault or alarm exists in real time, wherein the serious fault or alarm refers to diagnostic information of the protective equipment which must be stopped, such as frequency converter faults, sensor faults, water immersion alarm and the like.
Step S218: if the detection result in the step S217 is negative, the inverter driving motor is started to operate at the speed calculated by the PID in the step S330.
Step S900: after the single operation cycle of the distributed control unit is finished, since the controller is a loop execution program, the system automatically jumps to step S100 to execute, and so loops to ….
4. When the sub-water supply mode in the automatic mode selects the 'flow dynamic compensation mode', the system can dynamically adjust the flow compensation value according to the motor rotating speed variable. For the clear expression of the flow compensation value, the symbolic meaning is defined as follows:
Pfpressure feedback value (real-time)
PaTarget pressure value (real time)
PbBasic pressure value (static state)
PcSingle pump maximum compensation pressure value (static state)
FiRunning frequency value (real time)
FbBasic frequency value (static), typically 25Hz
FmaxMaximum frequency value (static), typically 50Hz
PicSingle pump compensation pressure value (real time)
n: number of pumps running
Parameter Pb、Pc、Fb、FmaxIt needs to be set. Pb、PcRespectively according to the water supply height and the flow rate of the actual application scene. FbAccording to the actual pump head, the meaning is that when the motor runs at the frequency, the actual pump outputThe lift is close to zero, FmaxIs the maximum operating frequency allowed for the pump motor. When the pump motor runs in real time at frequency Fi≤FbTime, target pressure value (real time) Pa= Pb(ii) a When the pump motor runs in real time at frequency Fi>FbTime, target pressure value (real time) Pa= Pb+ n·PicIn which P isic=[Pc/ (Fmax－Fb)]·(Fi－Fb). From this, the target pressure value (real time) P can be seenaIs a dynamic curve, the rule of which is changed along with the change of water consumption. System with Pa、PfAfter PID operation, a pressure feedback value (real-time) P is obtainedfThe curve law is to follow the target pressure value (real-time) PaThe flow dynamic compensation function is realized. It is worth mentioning that when the distributed control unit runs autonomously off the central management coordination unit, the target pressure value (real-time) P is calculateda= Pb+ n·PicWhen n is equal to 1, n is equal to 1.
5. And (4) keeping the pressure at a low flow rate for standby based on a multivariable weight algorithm. Four steps are required to achieve this function: 1. setting variable weight distribution parameters of a pump motor; 2. setting static parameters when the flow is zero; 3. calculating a real-time total evaluation percentage value; 4. the percentage threshold value, increments of dwell standby acknowledgement time are evaluated. The specific implementation method comprises the following steps:
motor variable weight assignment parameters set typical values: frequency Fw=40%, power Pw=30% torque Tw=20% current Cw= 10%. At zero flow, static parameter setting: firstly, making the system be in the running state of single pump, secondly slowly closing water outlet valve of pump group, the criterion of slowly closing valve is that the pressure value of water outlet is kept stable, after the valve is completely closed, recording that the frequency, power, torque and current value are respectively F0、P0、T0、C0. Calculating the real-time total evaluation percentage P: fi、Pi、Ti、CiRespectively expressed as real-time frequency, power, torque, current; pF、PP、PT、PCExpressed as real time frequency percentage, power percentage, torque percentage, current percentage, respectively. Real-time total assessment percentage formula P = PF+PP+PT+PCIn which P isF= [(Fw－1)/ F0]·Fi+1 (when P isF＜FwThen let PF=Fw)、PP=[(Pw－1)/ P0]·Pi+1 (when P isP＜PwThen let PP=Pw)、PT=[(Tw－1)/T0]·Ti+1 (when P isT＜TwThen let PT=Tw)、PC=[(Cw－1)/ C0]·Ci+1 (when P isC＜CwThen let PC=Cw). Evaluation of percentage threshold, incremental increase of dwell standby confirmation time: when the distributed control units operate autonomously or more than 2 control units participate in the linkage central management coordination unit to detect that only 1 pump operates, initializing the evaluation percentage threshold value Ps=10% (typical value), pressure-holding standby confirmation time value Ts=60s (typical value). When the real-time pressure feedback value is approximately equal to the real-time target pressure value Pa(the decision criterion is | Pf－PaLess than 0.01 MPa) and the real-time total evaluation percentage P is more than or equal to PsCoexisting and having a duration of not less than TsIn time, the system is stopped and pressure is maintained, and the standby duration T of pressure maintaining is comparediAnd T0(typically 60s) size. If Ti＜T0Then, for the evaluation percentage threshold value PsIncreasing by 10 percent, and circulating in such a way until PsNo longer increasing after = 100%. When P is presentsIf not less than 100%, the waiting confirmation time value T is set for the pressure holdingsThe doubling treatment was carried out until it was equal to 8 hours and no longer doubled. If T appearsi≥T0Then, the evaluation percentage threshold value P is initializeds=10%, pressure-maintaining standby confirmation time value Ts=60s。
Claims (5)
1. Hardware composition: in order to more clearly express the quantitative relation between each elementNow, the symbol N (1. ltoreq. n.ltoreq.8, N belongs to N)+）、m（n≤m≤3n,m∈N+) The product is composed of 1 central management coordination unit, n mutually independent distributed control units capable of running independently, m pumps, 2n digital quantity sensors and 2n analog quantity sensors, the connection mode of each unit is Ethernet communication, the central management coordination unit and the distributed control units are respectively arranged in a mechanical cabinet body with a modular structure, 1+ n mechanical cabinet bodies are totally arranged, the mechanical cabinet bodies are designed in a modular structure, the appearance and the size of the mechanical cabinet bodies are the same in a similar power gradient group, and other 5 surfaces can be spliced at will except surfaces with operation knobs and indicator lamps.
2. The central management coordination unit is mainly composed of a mechanical cabinet body with a modular structure, a touch screen, a state indicator lamp, an operation knob, a circuit breaker, a controller and a switch power supply, an Ethernet interface, a serial interface, a digital quantity IO interface and an analog quantity IO interface are reserved, the central management coordination unit is only responsible for management coordination and serves the distributed control units, control right is given to each distributed control unit, the central management coordination unit takes Ethernet (TCP/IP) as a communication carrier and the identity of a client side to actively connect a server of the distributed control units, and supports the same-segment, cross-segment star or ring network topology structure cascade connection, the central management coordination unit is actively connected with a remote cloud server as the client side, actively uploads state information of a control system, downloads configuration information of the cloud server, and remote monitoring function is realized through a web browser, a mobile phone APP and a small WeChat program,
the central management coordination unit and the distributed control unit respectively generate heartbeat pulse marks and simultaneously mutually detect the heartbeat pulse marks of the other party so as to judge whether the other party is in an active state and whether the communication is normal or not, the real-time clock RTC of the central management coordination unit has two setting methods which coexist, one is actively connected with an NTP server, the other is manually set time through a touch screen, the real-time clock RTC of the distributed control unit is synchronized with the real-time clock RTC of the central management coordination unit once every 24 hours or is synchronized once when the distributed control unit is on line again after being disconnected with a network of the central management coordination unit, when the central management coordination unit detects that the heartbeat of the distributed control unit exists, is in a remote control state and does not cause serious shutdown fault or alarm, the control unit is brought into a unified scheduling management array to participate in system linkage, the method for collecting the pressure value of the water inlet end of the control system comprises the steps of firstly reading the pressure value of the water inlet end of each control unit, then removing the analog quantity sensor value which has a fault, and finally taking the minimum value of all the values as the water inlet pressure value of the control system, wherein the method for collecting the pressure value of the water outlet end of the control system comprises the steps of firstly reading the pressure value of the water outlet end of each control unit, then removing the analog quantity sensor value which has a fault, taking the maximum value as the water outlet pressure value of the control system when the difference value delta between the maximum value and the minimum value of all the values is less than 0.04MPa, sending the value to each control unit as a common pressure feedback value P, taking the minimum value as the water outlet pressure value of the control system when the difference value delta between the maximum value and the minimum value of all the values is more than or equal to 0.04MPa, generating an alarm message of overla, after receiving the message, each control unit takes the display value of the analog sensor at the water outlet end of the local pump group as a pressure feedback value P, and when the central management coordination unit is in a starting state and detects that no serious fault or alarm occurs in the whole control system, if the feedback pressure value P is less than a set pressure value S and the load of the control unit is more than 98%, 1 control unit is added to be put into operation; if the feedback pressure value P is approximately equal to the set pressure value S, balancing the load of the distributed control units (the number of the control units which are put into operation is more than or equal to 2); if the feedback pressure value P is larger than the set pressure value S and the load of the control unit is less than 10 percent, reducing 1 control unit to be put into operation,
the touch screen of the central management coordination unit visualizes the process state and parameter setting of the system to realize man-machine interaction, after the process parameter setting of each control unit is completed on the touch screen, the process parameter setting is transmitted to the central management coordination unit through the Ethernet, and then the process parameter setting is transmitted to each distributed control unit through the Ethernet by the central management coordination unit, the state information transmission of each control unit is transmitted to the touch screen of the central management coordination unit along opposite paths, and the main content on the touch screen comprises the real-time state information, the real-time fault/alarm, the parameter setting, the historical fault/alarm, the system operation log and the historical pressure value information of a water inlet and outlet end of the system of the whole control system.
3. The distributed control unit mainly comprises a mechanical cabinet body with a modular structure, a state indicator lamp, an operation knob, a circuit breaker, a controller, a switch power supply, a frequency converter, 2 digital quantity sensors and 2 analog quantity sensors, wherein the controller supports the simultaneous input of analog quantity voltage (0-5V/0-10V) and current (4-20 mA/0-20 mA), a touch screen of the central management coordination unit is provided with a voltage/current input signal software switch to adapt to two types of output signal analog quantity sensors, the controller and the frequency converter of the distributed control unit are in communication connection and exchange data in a field bus (such as a Modbus RTU) mode, the real-time state data frequency, current, power, torque and the like of the frequency converter are read, the start and stop of the frequency converter are controlled, the operation frequency is increased and the fault is reset, 1 distributed control unit supports the access of 1-3 pumps, the water inlet and outlet ends of the pumps share a common pipeline which is respectively called as a water inlet main pipe and a water outlet main pipe, 1 digital quantity sensor and 1 analog quantity sensor are respectively arranged on the water inlet main pipe and the water outlet main pipe of the pumps, when the digital quantity and the analog quantity sensors of the water inlet main pipe detect that the water inlet pressure is too low or the digital quantity of the water outlet main pipe and the analog quantity sensors detect that the water outlet pressure is too high, the control unit stops the machine and outputs corresponding alarm information, when the digital quantity and the analog quantity sensors of the water inlet main pipe detect that the water inlet pressure is too high or the digital quantity of the water outlet main pipe and the analog quantity sensors detect that the water outlet pressure is too low, the control unit only outputs corresponding alarm information, the distributed control unit is provided with a hardware local/remote operation switching function knob, field manual work can determine whether the control unit participates in system linkage, and determine whether other distributed control units operate or not, the distributed control unit communicates with the central management coordination unit in real time, sends local state information, receives configuration information of the central management system unit, detects 'heartbeat flag bit', 'system water outlet pressure value too low flag bit', 'system water outlet pressure value deviation is more than or equal to 0.04MPa flag bit', the 3 flag bits occur 1 at will, the distributed control unit starts an autonomous operation mode immediately, the water outlet pressure value of the local pump is used as a pressure feedback value, the shared pressure feedback value is used as a pressure feedback value after the 3 flag bits are reset, the whole system is put into the distributed control unit to participate in system linkage, the distributed control unit performs PID operation by using the pressure feedback value and a pressure set value, and an operation result is sent to the frequency converter in a field bus communication mode, when the operation information sent by the central management coordination unit is received and the water pressure at the water inlet end and the water outlet end of the pump is normal and no serious fault or alarm exists, the motor of the frequency converter driving pump is started to operate at the speed calculated by PID.
4. Dynamically adjusting the flow compensation value based on the motor speed variable, wherein for clearly expressing the flow compensation value, the definition sign meaning is as follows:
Pfpressure feedback value (real-time)
PaTarget pressure value (real time)
PbBasic pressure value (static state)
PcSingle pump maximum compensation pressure value (static state)
FiRunning frequency value (real time)
FbBasic frequency value (static), typically 25Hz
FmaxMaximum frequency value (static), typically 50Hz
PicSingle pump compensation pressure value (real time)
n: number of pumps running
Parameter Pb、Pc、Fb、FmaxNeeds to set Pb、PcRespectively according to the water supply height and flow rate of the actual application scene, FbAccording to the actual pump head, the meaning of the pump head is that when the motor runs at the frequency, the actual pump head output by the pump is close to zero, FmaxIs the maximum operating frequency allowed by the pump motor when the pump is runningReal-time running frequency F of motori≤FbTime, target pressure value (real time) Pa= Pb(ii) a When the pump motor runs in real time at frequency Fi>Fb(if the pump is operating at power frequency, Fi50 Hz), target pressure value (real time) Pa= Pb+ n·PicIn which P isic= [Pc/ (Fmax－Fb)]·(Fi－Fb) From this, the target pressure value (real time) P can be seenaIs a dynamic curve, the law of which is changed following the change of water consumption, and the system is represented by Pa、PfAfter PID operation, a pressure feedback value (real-time) P is obtainedfThe curve law is to follow the target pressure value (real-time) PaThe flow dynamic compensation function is realized.
5. The small flow pressure maintaining standby based on the multivariable weight algorithm needs four steps to realize the function: a. setting variable weight distribution parameters of a pump motor; b. setting static parameters when the flow is zero; c. calculating a real-time total evaluation percentage value; d. evaluating the percentage threshold value and increasing the pressure maintaining standby confirmation time, and specifically realizing the method as follows:
motor variable weight assignment parameters set typical values: frequency Fw=40%, power Pw=30% torque Tw=20% current Cw=10%, at zero flow, static parameter settings: firstly, making the system be in the running state of single pump, secondly slowly closing water outlet valve of pump group, the criterion of slowly closing valve is that the pressure value of water outlet is kept stable, after the valve is completely closed, recording that the frequency, power, torque and current value are respectively F0、P0、T0、C0Calculating the real-time total evaluation percentage P: fi、Pi、Ti、CiRespectively expressed as real-time frequency, power, torque, current; pF、PP、PT、PCExpressed as real-time frequency percentage, power percentage, torque percentage, current percentage, respectively, real-time total estimate percentage formula P = PF+PP+PT+PCIn which P isF= [(Fw－1)/ F0]·Fi+1 (when P isF＜FwThen let PF=Fw)、PP=[(Pw－1)/ P0]·Pi+1 (when P isP＜PwThen let PP=Pw)、PT=[(Tw－1)/T0]·Ti+1 (when P isT＜TwThen let PT=Tw)、PC=[(Cw－1)/ C0]·Ci+1 (when P isC＜CwThen let PC=Cw) Evaluating the percentage threshold value and increasing the pressure maintaining standby confirmation time: when the distributed control units operate autonomously or more than 2 control units participate in the linkage central management coordination unit to detect that only 1 pump operates, initializing the evaluation percentage threshold value Ps=10% (typical value), pressure-holding standby confirmation time value Ts=60s (typical value), when the real-time pressure feedback value ≈ real-time target pressure value Pa(the decision criterion is | Pf－PaLess than 0.01 MPa) and the real-time total evaluation percentage P is more than or equal to PsCoexisting and having a duration of not less than TsIn time, the system is stopped and pressure is maintained, and the standby duration T of pressure maintaining is comparediAnd T0(typically 60s) if Ti＜T0Then, for the evaluation percentage threshold value PsIncreasing by 10 percent, and circulating in such a way until PsNo longer increasing after =100%, when PsIf not less than 100%, the waiting confirmation time value T is set for the pressure holdingsDoubling the sample until the time is 8 hours, and if T appears, no doubling is carried outi≥T0Then, the evaluation percentage threshold value P is initializeds=10%, pressure-maintaining standby confirmation time value Ts=60s。
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| CN113433978A (en) * | 2021-07-01 | 2021-09-24 | 华能国际电力股份有限公司上安电厂 | Unit water supply control system optimization method |
| CN113931830A (en) * | 2021-11-12 | 2022-01-14 | 华能伊敏煤电有限责任公司 | Combined type variable frequency control system and method for open-pit coal mine open-drainage system |
| CN114922255A (en) * | 2022-06-09 | 2022-08-19 | 山东华立供水设备有限公司 | Non-negative-pressure water supply system based on Internet of things control and implementation method thereof |
| WO2022146346A3 (en) * | 2020-12-30 | 2022-10-06 | Erciyes Universitesi Strateji Gelistirme Daire Baskanligi | An artificial bee colony algorithm based method optimizing energy efficiency for water supply system with co-operating multiple pumps |
| CN115951800A (en) * | 2023-03-10 | 2023-04-11 | 上海泰矽微电子有限公司 | Waterproof system for processing capacitive touch through pressure sensing technology |
| CN117872935A (en) * | 2024-03-08 | 2024-04-12 | 浙江南方智慧水务有限公司 | Water supply control method based on multi-redundancy neural network |
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