PLC programming-free pump group rotation control method based on constant pressure water supply controller

Abstract

This invention discloses a PLC-free pump group rotation control method based on a constant pressure water supply controller, belonging to the field of pump group rotation control technology. It includes establishing a corresponding regulation object model for each pump in the pump group and configuring a uniquely bound regulation memory unit for each pump. During normal operation, only the regulation memory unit corresponding to the pump currently participating in frequency conversion regulation is allowed to participate in regulation calculations. When the pump group rotation judgment condition is met, the controller enters the rotation control stage. After the pump group rotation is completed, the initial regulation state of the new pump is formed. This invention clearly distinguishes between the normal constant pressure regulation stage and the pump group rotation stage at the control logic level, avoiding regulation oscillations and frequent large speed adjustments during rotation. Simultaneously, it embeds the traditional pump group rotation control, which relies on PLC logic and manual parameter tuning, into a model-based and state-machine-based control process within the controller, eliminating the need for conservative strategies such as reducing PID gain and amplifying the proportional band to suppress oscillations.

Description

Technical Field

[0001] This invention relates to the field of pump set rotation control technology, specifically a PLC-free pump set rotation control method based on a constant pressure water supply controller. Background Technology

[0002] Constant pressure water supply systems are widely used in residential communities, commercial buildings, industrial parks, and municipal water supply systems. Their core objective is to achieve stable pressure control in the water supply network by adjusting the operation of water pumps under fluctuating water load conditions. Existing constant pressure water supply systems typically consist of pressure sensors, frequency converters, pump units, and control units. The control unit is responsible for coordinating the pump start-up, shutdown, speed regulation, and switching strategies based on real-time pressure feedback.

[0003] In constant-pressure water supply systems with multiple pumps operating in parallel, to avoid uneven mechanical wear, shortened lifespan, and increased maintenance costs caused by the long-term operation of a single pump, a pump rotation control mechanism is typically introduced. This mechanism allows multiple pumps to alternately assume the role of main or auxiliary pump during different operating cycles, thereby achieving load balancing and extending equipment lifespan. However, current pump rotation control technologies largely rely on programmable logic controllers (PLCs), using rotation logic programs, timing strategies, or runtime statistics programs to control pump switching. While the PLC-based implementation is flexible, it still has limitations in practical applications: firstly, PLC systems require professional personnel for program development, debugging, and maintenance, increasing deployment costs and technical barriers; secondly, for small- to medium-sized water supply systems or standardized pump station scenarios, PLC solutions suffer from functional redundancy and complex system structures, hindering rapid deployment and large-scale promotion. Furthermore, in some renovation projects or application scenarios with limited site conditions, the introduction of PLCs is often constrained by installation space, electrical interfaces, and system compatibility.

[0004] In recent years, with the continuous integration and intelligence of constant pressure water supply controllers, some controllers have basic capabilities such as pressure closed-loop control, multi-pump joint control and operation status monitoring. However, their pump group switching function is mostly limited to fixed logic or simple timing configuration, and it is still difficult to achieve flexible, reliable and adaptable pump group switching control under different working conditions without PLC programming.

[0005] In controllers like the CPC316, parameters such as pump switching time (TCHR), proportional band (PROP), and integral time (INTT) are set independently. However, in actual operation, pump switching alters the mechanical characteristics and flow-speed curve of the pump unit, while the PID parameters are still adjusted according to a single pump model. Under the same pressure deviation, the effectiveness of the PID output in regulating frequency is inconsistent when different pumps participate in the regulation. If the switching frequency is close to the PID integral time scale, implicit integral saturation or regulation lag may occur. This problem is not due to incorrect parameter settings, but rather a nonlinear mismatch caused by independent parameter configuration at the system level. In high-rise residential buildings, with significant fluctuations during morning and evening peak hours, and when the switching cycle is shortened to balance lifespan, the following problems may occur: significantly slower regulation or overshoot after switching, accumulation and stagnation of the integral term, and prolonged recovery time. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a PLC-free programmable pump group rotation control method based on a constant pressure water supply controller. To achieve the above objectives, this invention utilizes the following technical solution: a PLC-free programmable pump group rotation control method based on a constant pressure water supply controller, comprising:

[0007] Establish a corresponding regulation object model for each water pump in the pump group, and configure a uniquely bound regulation memory unit for each water pump. The regulation memory unit is used to record the cumulative pressure deviation state formed by the water pump during the constant pressure regulation process.

[0008] During normal operation, only the regulation memory unit corresponding to the water pump currently participating in frequency conversion regulation is allowed to participate in regulation calculations, while the regulation memory units of the other water pumps remain frozen.

[0009] When the pump set rotation judgment condition is met, the controller enters the rotation control stage, suspends the update of the regulation memory unit of the current regulating pump, and suppresses the influence of transient pressure disturbances caused by the rotation on the regulation output.

[0010] After the pump set rotation is completed, only the regulation memory unit corresponding to the newly participating water pump is activated to participate in the regulation calculation. The regulation memory state before the rotation is equivalently mapped according to the regulation object model of the water pump to form the initial regulation state of the new water pump.

[0011] Compared with the prior art, the embodiments of the present invention have at least the following beneficial effects:

[0012] (1) This invention provides a PLC-free pump group rotation control method based on a constant pressure water supply controller. It clearly distinguishes between the normal constant pressure regulation stage and the pump group rotation stage at the control logic level. Through mechanisms such as rotation state perception, regulation memory freezing, and frequency output locking, the transient pressure disturbances generated during the rotation process are no longer misinterpreted as sudden changes in water load. This design fundamentally cuts off the feedback chain of pressure sudden change → misjudgment → drastic frequency correction → secondary disturbance in the traditional system, avoiding regulation oscillations and frequent large speed adjustments during the rotation, thereby significantly improving the dynamic stability and predictability of the constant pressure water supply system under pump switching conditions.

[0013] (2) By establishing an independent regulation object model for each water pump and binding a unique regulation memory unit, the system can completely save the historical pressure deviation accumulation state formed by each pump during the regulation process. In addition, after the pump group is rotated, instead of simply activating the new pump and starting regulation from zero, the original regulation memory state is equivalently mapped based on the proportional relationship between the unit frequency pressure response coefficients of the two water pumps to generate an initial regulation state that matches the regulation sensitivity of the new pump. This mechanism of continuous state rather than control reset ensures that the regulation output remains smoothly connected in the time dimension, significantly reducing regulation lag, overshoot, and repeated corrections after rotation.

[0014] (3) This invention embeds the traditional pump group rotation control, which relies on PLC logic and manual parameter tuning, into a model-based and state-machine-based control process within the controller. By automatically acquiring the unit frequency pressure response coefficient, constructing a pressure-frequency mapping table, and introducing dynamic response parameters during the initialization phase, the controller can form differentiated adjustment object models for different pumps and different pipeline conditions. This not only reduces the cost of on-site commissioning and manual intervention but also enables the system to adapt to different pump types, aging levels, and changes in the operating environment, significantly improving the system's versatility, deployment efficiency, and long-term maintainability.

[0015] (4) By avoiding abrupt output of frequency commands and erroneous accumulation of regulation memory during the rotation process, the inverter and motor no longer suffer from frequent instantaneous acceleration, deceleration and current surges, effectively reducing thermal shock, mechanical stress and electrical losses. At the same time, the system does not need to suppress oscillations by conservative strategies such as reducing PID gain and amplifying proportional band, but can maintain a more active and efficient adjustment parameter configuration during normal operation, thereby improving response speed and energy efficiency while meeting pressure stability requirements.

[0016] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0018] Figure 2 This is a schematic diagram of the constant pressure water supply control system according to Embodiment 3 of the present invention.

[0019] Figure 3 This is a wiring diagram of the electrical cabinet of the constant pressure water supply control system according to Embodiment 3 of the present invention.

[0020] Figure 4 This is a schematic diagram of the logic flow of Embodiment 1 of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "around", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0023] Please see Figure 1 As shown in the figure, this embodiment of the invention provides a schematic flowchart of a PLC-free pump group rotation control method based on a constant pressure water supply controller, specifically including:

[0024] Example 1:

[0025] Please see Figure 4The diagram shows the logical flow of this embodiment. It describes a control logic for decoupling pump rotation and regulation in constant pressure water supply control. At startup, a regulation object model is established for each pump, and a uniquely bound regulation memory unit is configured. During normal constant pressure operation, the controller only allows the regulation memory unit corresponding to the pump currently participating in frequency conversion regulation to participate in the calculation; the regulation memory states of other pumps remain frozen. The controller periodically collects the pipeline pressure, compares it with the target pressure, generates a frequency regulation output, and continuously determines whether the pump rotation conditions are met. When the rotation conditions are not met, the original regulation closed loop is maintained; when the rotation conditions are met, the controller executes the pump rotation operation, freezing the regulation memory of the original pump and maintaining the original frequency output during the rotation phase. Then, it switches to the new regulating pump and initializes its regulation memory through regulation state mapping. After completion, it re-enters the normal constant pressure regulation process. This intuitively demonstrates the overall control logic of the coordinated operation of pump rotation and constant pressure regulation, clearly defining the boundary relationship between the normal regulation phase and the rotation control phase.

[0026] Establish a corresponding regulation object model for each water pump in the pump group, and configure a uniquely bound regulation memory unit for each water pump. The regulation memory unit is used to record the cumulative pressure deviation state formed by the water pump during the constant pressure regulation process.

[0027] The regulating memory unit includes at least:

[0028] The primary memory value is the main control memory value used to reflect the long-term cumulative trend of pressure deviation.

[0029] The second memory value is a state quantity used to reflect the historical adjustment intensity and duration of the water pump.

[0030] The third memory is used to record the reference value of the output command during the most recent adjustment.

[0031] The above memory values ​​are updated only when the corresponding water pump is selected as the current variable frequency control object.

[0032] To establish a corresponding regulating object model for each pump in the pump set, the specific process is as follows:

[0033] During the initialization phase, the controller establishes a set of equivalent regulation characteristic parameters for each water pump. The set of equivalent regulation characteristic parameters includes at least the unit frequency pressure response coefficient and the steady-state regulation sensitivity.

[0034] The specific method for obtaining the pressure response coefficient per unit frequency is as follows:

[0035] The controller performs the following test procedure when operating with a single pump independently:

[0036] With the fixed pipeline network in a stable water usage state, the current water pump is the sole variable frequency drive (VFD) actuator. The VFD output frequency is adjusted step-by-step according to a preset stepped change, where each step is a fixed frequency increment with the same amplitude between adjacent steps. After each frequency adjustment, the controller maintains the output frequency until the pipeline pressure reaches a new steady-state.

[0037] At each frequency step, the corresponding steady-state pressure value of the pipeline network is collected by a pressure sensor. The unit frequency pressure response coefficient of the water pump is calculated by the ratio of the step change in the output frequency of the frequency converter to the pressure change. The unit frequency pressure response coefficient is used to reflect the adjustment gain characteristics of the water pump under the current pipeline network conditions.

[0038] It should be noted that the pressure change refers to the difference in pipeline pressure from one steady-state value to the next after the inverter output frequency is adjusted from one step value to the next step value.

[0039] It should be noted that even for the same model of water pump, due to factors such as impeller wear, motor efficiency, installation location, and differences in pipeline resistance, some water pumps will experience a significant increase in pressure while others will experience a very small pressure change when the frequency changes are the same. If the controller continues to adjust the gain according to the same relationship between frequency and pressure changes after the rotation, the same output will produce completely different adjustment effects on different water pumps, resulting in slow adjustment, overshoot, or integral stagnation after the rotation.

[0040] In practice, the controller maintains the pipeline network in a stable water usage state. In this state, all pumps except the currently tested pump are shut down, leaving only the current pump as the sole variable frequency drive (VFD) device. A stable water usage state means that within a preset time window, the pipeline pressure variation remains within a predetermined allowable range, and no new water-using equipment is added or removed.

[0041] The controller calculates the unit frequency pressure response coefficient of the water pump based on the ratio of the pressure change to the frequency change. This unit frequency pressure response coefficient characterizes the steady-state response intensity of the water pump to the network pressure under the current network conditions and in response to frequency changes.

[0042] After completing the test of the current water pump, the controller stores the unit frequency pressure response coefficient of the pump in its internal parameter storage area, indexed by the pump identifier. Subsequently, the controller tests the remaining water pumps in the pump group in sequence according to the same test procedure, and obtains the corresponding unit frequency pressure response coefficient for each pump.

[0043] The methods for determining steady-state regulation sensitivity specifically include:

[0044] The controller divides the water pump into different adjustment sensitivity ranges based on the pressure response coefficient per unit frequency.

[0045] In this embodiment, the response coefficients of all water pumps are statistically sorted to form a response coefficient distribution interval. Based on a preset segmentation threshold, the intervals are divided into a high-sensitivity interval, a medium-sensitivity interval, and a low-sensitivity interval.

[0046] The controller constructs a pressure-frequency mapping table for the pump based on the unit frequency pressure response coefficient and the static resistance characteristics of the pipeline network. The pressure-frequency mapping table is used to predict the pressure response under arbitrary frequency changes. At the same time, dynamic response parameters are introduced, including pressure change delay time, inertial hysteresis, and integral cumulative effect. The dynamic characteristics of the pump are modeled as a set of state variables and difference equations, so that the model can simulate the pressure response process of pump start-up, shutdown, and frequency conversion regulation during the control process.

[0047] Dynamic response parameters include pressure change delay time, inertial hysteresis, and integral cumulative effect. Pressure change delay time refers to the time interval from the moment the controller outputs a frequency change command to the inverter until the pressure detection unit detects a identifiable change in the pipeline pressure. This time reflects the inherent system response delay resulting from the combined effects of pump mechanical response, water transfer within the pipeline, and sensor sampling. This parameter describes the initial hysteresis characteristics of the pressure response and distinguishes the time segment where "the command has been issued but the pressure has not yet changed," preventing the controller from repeatedly adding adjustments within this segment. When a single pump operates independently and the pipeline is in a stable water usage state, the controller performs a step frequency test on the current pump. The controller continuously acquires the output signal from the pressure detection unit and performs time series analysis on the pressure sensor input values. When the pressure change amplitude first exceeds the preset pressure change judgment threshold, this moment is recorded. The time difference between these two moments is determined as the pressure change delay time corresponding to the pump and stored as one of the pump's dynamic response parameters.

[0048] Inertial hysteresis refers to the phenomenon where, after a change in pump frequency, the pipeline pressure does not immediately reach a new steady-state value, but rather changes gradually, with the rate of change limited by factors such as water inertia, pipeline elasticity, and pump rotational inertia. This parameter describes the slow response characteristic caused by system inertia during pressure changes. Inertial hysteresis is used to characterize the rise or fall slope of the pressure change curve, preventing the controller from misjudging under- or over-regulating before the pressure has completed its inertial response. After completing the frequency step test and surviving the pressure change delay time, the controller continuously samples the pressure change process. The controller records the pressure values ​​at different times during the change from the initial steady-state value to the target steady-state value and calculates the pressure change rate over time curve. By fitting the time constant or slope change characteristics of the pressure change curve, the hysteresis parameter describing the inertial response is determined. This parameter is stored in numerical form and used to predict and limit the rate of pressure change during subsequent regulation.

[0049] The integral accumulation effect refers to the historical effect of a controller gradually accumulating adjustments to eliminate steady-state errors under persistent pressure deviations. This effect reflects the characteristic of the pump's output gradually changing over time under long-term deviations. This parameter characterizes the intensity of the impact of pressure deviation accumulation over time on the output during regulation, and is an important basis for preventing over-regulation triggered by short-term pressure disturbances. Under stable pump operation conditions, the controller artificially applies a constant target pressure deviation, for example, by fine-tuning the target pressure value to create a continuous deviation. While keeping this deviation constant, the controller records the change of the frequency converter output command over time and calculates the cumulative increment of the output per unit time. Based on the growth rate and cumulative magnitude of the output, the integral accumulation parameter corresponding to the pump is determined, which is used to constrain the growth rate and accumulation limit of the integral term in subsequent regulation processes.

[0050] Using the parameters mentioned above, the controller can internally simulate the dynamic impact of frequency changes on pressure, ensuring that the regulation output remains consistent with the actual pressure response and avoiding regulation oscillations caused by rotation or transient disturbances.

[0051] The controller divides each pump in the pump set into different regulation sensitivity ranges based on the unit frequency pressure response coefficient obtained by each pump in independent operation. Each range corresponds to a class of pumps with similar pressure response capabilities, so as to differentiate and process the regulation gain during pump set rotation or automatic adjustment.

[0052] The controller, taking into account the static resistance characteristics of the pipeline network, constructs a pressure-frequency mapping table for each water pump. Specifically, under steady-state pipeline conditions, the controller adjusts the pump's frequency converter output according to a preset frequency step, and collects the corresponding steady-state pressure values. By recording the correspondence between pressure changes and frequency changes, a discrete pressure-frequency data table is generated. Based on this data table, the controller can predict the pump's response to pipeline pressure under any frequency output condition, providing a reference for subsequent adjustment calculations.

[0053] It should be noted that in this embodiment, the static resistance characteristics of the pipeline network are not presented directly as independent parameters. Specifically:

[0054] In the process of collecting the corresponding steady-state pressure values ​​under steady-state pipeline network conditions, static resistance factors such as pipeline topology, pipe diameter, valve opening, and elevation difference remain unchanged. The steady-state pressure values ​​collected at different frequency points essentially reflect the balance result after the combined effect of pump characteristics and pipeline resistance curve. Therefore, the final "pressure-frequency mapping table" has actually solidified, mapped, and implicitly encoded the static resistance characteristics of the pipeline network in the data table.

[0055] It should also be noted that steady-state pressure refers to the pressure value measured when the following conditions are met simultaneously:

[0056] The water pump operating frequency remains constant and the pressure sensor readings fluctuate within the allowable error range over time.

[0057] Based on the static mapping, dynamic response parameters are established, including pressure change delay time, pipeline inertial hysteresis, and integral cumulative effect. In specific implementation, the controller represents the dynamic behavior of each water pump as a set of state variables and uses difference equations to update the state variables, describing the dynamic process of pressure change over time during pump start-up, shutdown, and frequency conversion regulation. During regulation calculations, the controller predicts short-time pressure response by simulating the state changes of the difference equations, avoiding misinterpreting transient disturbances as sudden changes in water usage at the user end, thereby achieving accurate control of the regulation output.

[0058] The controller integrates the pressure-frequency mapping table, dynamic state equation, steady-state regulation sensitivity, and historical regulation memory of each pump to form a complete regulation object model, and stores it in the internal parameter storage area with the pump number as the index.

[0059] It should be noted that, in this embodiment, the above integration is not a simple data splicing, but rather a structured encapsulation and correlation modeling of multiple types of parameters according to a unified adjustment calculation logic. Specifically, it can be implemented in the following way:

[0060] A standardized data structure is established, using a single water pump as the smallest regulating object. This structure uses the pump number as a unique index to locate the corresponding regulating object model within the controller. All parameters, statuses, and historical information related to this water pump are bound to this index, ensuring the consistency and traceability of regulation calculations.

[0061] The pressure-frequency mapping table is used as a static characteristic submodule of the regulated object to describe the steady-state pressure response of the pump-pipeline system at different operating frequencies, providing a basic reference for regulation conversion and feedforward prediction.

[0062] The dynamic state equation is used as a dynamic characteristic submodule of the controlled object to characterize the inertia, hysteresis and cumulative characteristics of the pressure response. Its state variables are directly associated with the control memory unit to maintain control continuity between adjacent control cycles.

[0063] Based on this, the steady-state regulation sensitivity is embedded as a regulation gain parameter into the dynamic state equation or regulation law to perform scale correction on the frequency regulation amount, so that different water pumps can produce comparable and controllable regulation responses under the same pressure deviation.

[0064] By using historical regulation memory as the initial condition of the dynamic state equation and the internal state storage area, and binding it to the current control cycle for real-time reading and writing, the regulation state can be inherited and updated in the time dimension.

[0065] Each regulation object model is bound to a unique regulation memory unit, which is used to record the cumulative pressure deviation status and output command history of the water pump during the constant pressure regulation process.

[0066] During pump rotation or adjustment, the controller reads the current pump's adjustment object model, combines real-time pressure deviation and historical memory, and calculates the required inverter output to achieve the continuity and stability of closed-loop pressure control, while avoiding cross-pump cumulative error or integral lag.

[0067] During normal operation, only the regulation memory unit corresponding to the water pump currently participating in frequency conversion regulation is allowed to participate in regulation calculations, while the regulation memory units of the other water pumps remain frozen.

[0068] During normal operation, the controller first determines the pump number according to the internal pump group management logic, marks the pump currently participating in frequency conversion regulation, and sets its corresponding regulation memory unit to the active state, allowing the regulation memory unit to receive real-time pressure sensor input values ​​from the pressure sensor.

[0069] The above identification process is completed based on the pre-configured pump number.

[0070] Within each control cycle, the controller acquires the real-time pressure sensor input value from the pressure sensor, and performs filtering and quantization processing on the signal to obtain the pressure sensor input value for the current control cycle.

[0071] It should be noted that the pressure sensor can be a current-type or voltage-type pressure transmitter, and its output signal is acquired through the analog input port of the controller. The controller performs range conversion on the acquired raw signal, converting it into the corresponding pipeline pressure value, which is then used as the basis for adjustment calculations.

[0072] Read the pressure sensor input value corresponding to the currently active water pump, compare the pressure sensor input value with the set target pressure, and calculate the pressure deviation by subtracting the difference.

[0073] It should be noted that when the water pump participates in regulation for the first time, the pressure deviation accumulation state in the corresponding regulation memory unit is initialized to the preset reference value. The control cycle is set by the controller's internal timer, and its cycle length is determined during the system parameter configuration stage, and is consistent with the pressure sampling cycle and the frequency converter response cycle to ensure the timing consistency of the regulation calculation.

[0074] During each control cycle, the controller performs the following steps for the currently active water pump:

[0075] The controller invokes the corresponding adjustment memory unit for the water pump to perform cumulative calculations and integral operations on the pressure deviation, generating the frequency adjustment output for the current control cycle. After completing the pressure deviation accumulation update, the controller performs integral adjustment operations based on the updated pressure deviation accumulation state and the adjustment parameters stored in the adjustment memory unit, mapping the pressure deviation accumulation state to a frequency adjustment quantity. Numerically, the integral adjustment operation converts the pressure deviation accumulation state into the frequency correction value required for the current control cycle, reflecting the adjustment trend required for the water pump to maintain the target pressure during continuous operation.

[0076] It should be noted that, in this embodiment, the adjustment parameters stored in the adjustment memory unit do not refer to control parameters in general, but rather to internal state variables and constraint parameters that directly correspond to the specific water pump adjustment object model and need to maintain consistency before and after the rotation. The adjustment parameters include at least the following:

[0077] The regulation memory unit stores a pressure deviation accumulation parameter. This parameter represents the discrete cumulative result of the deviation between the target pressure and the actual pressure within a continuous control cycle, and is the core state variable of the integral regulation operation. This parameter records the cumulative deviation state at the end of the previous control cycle in numerical form, which is used as the initial condition for the integral operation of the current control cycle to prevent cross-cycle state loss during regulation.

[0078] The regulation memory unit stores integral weight parameters. These parameters limit the impact of a unit pressure deviation on the frequency regulation within a unit control cycle, reflecting the regulation gain level of the pump under current pipeline conditions. The integral weight parameters correspond one-to-one with the pump's unit frequency pressure response coefficient and steady-state regulation sensitivity level, ensuring that under the same pressure deviation conditions, the frequency regulation generated by different pumps remains consistent with their physical regulation capabilities.

[0079] The regulation memory unit stores integral upper and lower limit constraint parameters. These parameters limit the numerical range of the pressure deviation accumulation parameter. When the accumulated value reaches the preset upper or lower limit, the controller stops accumulating to prevent irreversible integral drift during sudden changes in water load or pump rotation. These upper and lower limit parameters are stored in specific numerical form for real-time comparison and constraint during regulation calculations.

[0080] The regulation memory unit stores regulation status flag parameters. These parameters indicate the current state of the regulation memory unit, including whether it is active, frozen, or in a transitional frozen state. Based on these status flag parameters, the controller determines whether to allow read / write operations on the regulation memory unit and whether to participate in the regulation calculations of the current control cycle.

[0081] The adjustment memory unit stores the most recent valid adjustment output record parameters. These parameters are used to record the frequency adjustment output value generated by the pump during its most recent participation in frequency conversion regulation, serving as a reference benchmark during pump set rotation recovery or equivalent mapping to maintain the continuity of frequency output before and after rotation.

[0082] The controller combines the calculated frequency adjustment amount with the current operating frequency reference of the water pump to generate a frequency adjustment output command for the current control cycle. This command is then sent to the frequency converter to control the pump's speed variation within the current control cycle. Simultaneously, the controller writes the updated pressure deviation accumulation status and corresponding adjustment results back to the corresponding adjustment memory unit of the water pump, serving as the initial state for the next control cycle's adjustment calculation. Through this process, the frequency adjustment output maintains temporal continuity and ensures that the adjustment behavior always corresponds one-to-one with the current water pump's historical adjustment state.

[0083] It should be noted that the frequency regulation output command includes the target operating frequency command, frequency increase / decrease direction, and amplitude constraint command. The target operating frequency command is the direct control target of the inverter within the current control cycle, obtained by superimposing the current pump operating frequency reference with the frequency regulation amount calculated for this cycle. The operating frequency reference is usually derived from the pump's steady-state setpoint or the actual output frequency of the previous control cycle, while the frequency regulation amount reflects the real-time correction result of the pressure deviation after processing by the regulation algorithm. This target frequency ensures that the pump speed changes continuously over time, avoiding sudden changes caused by rotation or disturbances. Before the frequency increase / decrease direction and amplitude constraint command are actually sent to the inverter, the controller performs legality and safety constraint processing on the target operating frequency, including the maximum frequency increase rate, the maximum frequency decrease rate, and the allowable frequency change amplitude per cycle.

[0084] The generated adjustment output command is sent to the frequency converter to control the change of water pump speed, and at the same time the pressure deviation accumulation status is written into the adjustment memory unit of the pump.

[0085] Subsequently, the controller sets the regulation memory units corresponding to all pumps in the pump group that are not currently involved in regulation to a frozen state.

[0086] It should be noted that in a constant pressure water supply system, different pumps have different power, head, and flow characteristics, resulting in inconsistent pressure responses caused by unit frequency changes. If multiple pumps share the same regulation memory, the accumulated historical state will continue to affect the new pump after a switch, leading to regulation mismatch. Therefore, this embodiment maintains a separate regulation memory unit for each pump within the controller, and during normal operation, only the regulation memory unit corresponding to the pump currently participating in frequency conversion regulation is allowed to participate in the calculation, while the remaining regulation memory units remain frozen, fundamentally cutting off the mutual influence of cross-pump regulation history.

[0087] When the pump set rotation judgment condition is met, the controller enters the rotation control stage, suspends the update of the regulation memory unit of the current regulating pump, and suppresses the influence of transient pressure disturbances caused by the rotation on the regulation output.

[0088] The pump unit rotation determination conditions are continuously monitored by the controller during normal operation and are triggered by quantifiable and identifiable operating parameters. Specifically, they include a combination of one or more of the following conditions. When any one condition is met, the controller determines that the pump unit rotation control phase has begun. These conditions include: rotation determination conditions based on running time, rotation determination conditions based on the number of start-stop cycles, rotation determination conditions based on operating load characteristics, and rotation determination conditions based on operating status.

[0089] The rotation determination conditions based on running time specifically include: the controller records the cumulative running time of each water pump. When the cumulative running time of the water pump currently participating in the frequency conversion regulation exceeds the preset pump replacement time threshold, the controller determines that the water pump meets the rotation determination conditions based on running time. The cumulative running time is based on the controller's internal time base and is only accumulated when the water pump is in the running state. The timing is paused when the pump is stopped, in hibernation, or in a fault state.

[0090] The rotation determination condition based on the number of start-stop cycles specifically includes: the controller counts the number of start-stop cycles of each water pump, and when the number of start-stop cycles of the water pump currently participating in the frequency conversion regulation reaches the preset upper limit of the number of start-stop cycles within the statistical period, the controller determines that the water pump meets the rotation determination condition based on the number of start-stop cycles.

[0091] The rotation determination conditions based on operating load characteristics specifically include: the controller monitors whether the water pump currently participating in frequency conversion regulation is higher than the preset high frequency threshold within the statistical period based on the operating frequency fed back by the frequency converter. When the continuous operating frequency is higher than the preset high frequency threshold and the continuous operating time exceeds the set duration, the controller determines that the water pump meets the rotation determination conditions based on operating load characteristics.

[0092] The rotation determination conditions based on operating status specifically include: when an abnormal operating status is detected in the water pump currently participating in the frequency conversion regulation, the controller determines that the water pump meets the rotation determination conditions based on operating status and switches to other water pumps in advance to undertake the regulation task.

[0093] It should be noted that abnormal operating states in this embodiment include hydraulic operation abnormalities, dynamic response abnormalities, electrical operation abnormalities, and mechanical operation abnormalities. Hydraulic operation abnormalities are mainly manifested as a significant increase in the deviation between the pump output and the control command. The controller detects this by comparing the rate of change of pressure deviation between the target pressure and the real-time pressure signal. If the pressure deviation remains greater than a threshold within a preset time window, a hydraulic operation abnormality is determined. Dynamic response abnormalities refer to a situation where the detected pressure change delay time significantly exceeds a set upper limit, indicating a dynamic response abnormality. Electrical operation abnormalities are mainly detected through the operating parameters of the frequency converter and motor side. Real-time acquisition of motor current, input power, and frequency converter status codes is performed. If the current exceeds a safety threshold under the same frequency conditions, an electrical operation abnormality is determined. Mechanical operation abnormalities are identified by the controller through detecting vibration amplitude and vibration spectrum characteristics.

[0094] The controller enters the rotation control phase, pausing the update of the regulation memory unit for the currently regulating water pump. Specifically, this includes:

[0095] The controller records the number of the water pump currently participating in the frequency conversion regulation, as well as the accumulated pressure deviation status and the most recent frequency regulation command stored in the corresponding regulation memory unit of that water pump.

[0096] After recording is completed, the controller sets an update prohibition flag for the regulation memory unit, so that the regulation memory unit will no longer receive new pressure deviation signal inputs during the rotation control phase.

[0097] During each control cycle of the rotation control phase, the controller continues to collect the pressure sensor input value output by the pressure sensor. However, the collected pressure sensor input value is only used for rotation status monitoring and is not used as the input quantity of the regulation memory unit to participate in the regulation calculation.

[0098] The controller maintains the frequency adjustment command recorded before the start of the rotation as a fixed output and continuously outputs the command to the frequency converter. The controller blocks the write operation to the adjustment memory unit, so that the accumulated pressure deviation value stored in the adjustment memory unit remains constant during the rotation control phase and does not change with the instantaneous change of the pressure sensor input value. This frozen state continues until the pump group switching action is completed and the controller exits the rotation control phase.

[0099] Suppressing the impact of transient pressure disturbances caused by rotation on the regulated output specifically includes:

[0100] Transient pressure disturbances refer to unsteady pressure changes in the pipeline network caused by the switching of the executing object during pump unit rotation.

[0101] The impact on the regulation output specifically includes pressure disturbances being misidentified as pressure deviations and directly participating in the regulation calculation.

[0102] The specific inhibition process includes:

[0103] After determining that the pump set rotation control phase has been entered, the controller sets the update prohibition state for the regulation memory unit corresponding to the currently regulating water pump.

[0104] In this state, the pressure sensor input value output by the pressure detection unit no longer participates in the pressure deviation accumulation calculation and does not trigger the write operation of the adjustment memory unit.

[0105] The controller locks the frequency adjustment command calculated most recently before the rotation trigger and continuously outputs the command during the rotation control phase.

[0106] Transient pressure disturbances exist only in the physical pipeline network, do not enter the regulation operation link, and are not transformed into changes in regulation output.

[0107] After the pump unit switching is completed and the recovery conditions are met, the controller removes the update prohibition state, allowing the pressure sensor input value to participate in the regulation calculation again.

[0108] It should be noted that the recovery conditions include: pressure stability condition, stable operation condition of the newly activated water pump, and minimum switching protection time condition, all of which must be met simultaneously in this embodiment.

[0109] Pressure stability condition. Within the preset observation time window, if the fluctuation range of the pressure observation value sampled by the pressure sensor is lower than the preset pressure fluctuation threshold, and the pressure change rate is within the allowable range, it indicates that the pipeline network has completed the switching transient and entered a quasi-steady state.

[0110] The newly activated water pump has reached stable operating conditions. The newly assigned water pump has reached the target frequency, and its power change rate is lower than the set power change threshold.

[0111] Minimum switching protection time condition. After the automatic pump unit switching is completed, the preset minimum freeze time has been met.

[0112] After the pump set rotation is completed, only the regulation memory unit corresponding to the newly participating water pump is activated to participate in the regulation calculation. The regulation memory state before the rotation is equivalently mapped according to the regulation object model of the water pump to form the initial regulation state of the new water pump.

[0113] Only the regulation memory unit corresponding to the newly regulated water pump is activated to participate in the regulation calculation, specifically including:

[0114] The controller determines the number of the water pump that has completed its rotation and is currently in variable frequency operation, and marks the water pump as the current regulation object. This mark is used to establish a unique correspondence between the regulation object and the regulation memory unit within the controller.

[0115] The controller clears the update prohibition state set in the rotation control phase, and only unfreezes the regulation memory unit corresponding to the current regulation object, restoring the regulation memory unit to a readable and writable state. The controller keeps the regulation memory units corresponding to other water pumps in a frozen state.

[0116] During each adjustment cycle, the controller compares the pressure sensor input value collected by the pressure detection unit with the target pressure value, calculates the pressure deviation, and inputs only the pressure deviation into the adjustment memory unit corresponding to the current adjustment object.

[0117] Based on the accumulated pressure deviation and the model of the regulated object stored in the regulation memory unit, the controller calculates a new frequency regulation command and outputs the command to the variable frequency drive unit to control the current pump speed change. The calculation process for the frequency regulation command is the same as described above.

[0118] After the adjustment calculation is completed, the controller writes the accumulated pressure deviation state formed in this adjustment cycle into the adjustment memory unit.

[0119] Based on the regulating object model of the water pump, the regulating memory state before the rotation is equivalently mapped to form the initial regulating state of the new water pump. The specific processing conditions are as follows:

[0120] The controller reads the accumulated pressure deviation value stored in the regulation memory unit corresponding to the original regulating water pump before the rotation occurs, and uses it as the mapping input benchmark. The accumulated pressure deviation value reflects the regulation demand formed by the long-term deviation between the pipeline pressure and the target pressure before the rotation.

[0121] It should be noted that the pressure deviation cumulative state value is an internal state variable formed by the controller performing integral calculations on the pressure deviation over multiple control cycles during the closed-loop constant pressure regulation process. The pressure deviation cumulative state value is used to characterize the long-term regulation required to maintain the target pressure under the current pipeline operating conditions. Its value gradually accumulates as the pressure deviation continues to exist and is stored in the regulation memory unit of the corresponding water pump.

[0122] The controller calls the unit frequency pressure response coefficients of the regulation object models corresponding to the original regulating water pump and the new regulating water pump respectively. Based on the proportional relationship between the unit frequency pressure response coefficients of the two water pumps, the controller calculates the mapping coefficient of the regulation memory state. The mapping coefficient is equal to the ratio of the unit frequency pressure response coefficient of the original regulating water pump to the unit frequency pressure response coefficient of the new regulating water pump.

[0123] After obtaining the mapping coefficient, the controller multiplies the cumulative pressure deviation state value before the rotation by the mapping coefficient to generate an equivalent cumulative pressure deviation state value that matches the adjustment sensitivity of the new water pump. This equivalent cumulative pressure deviation state value serves as the initial storage content of the new water pump adjustment memory unit.

[0124] After the writing is completed, the controller marks the regulation memory unit as initialized and removes the freeze restriction on the regulation memory unit during the rotation control phase, so that it can normally receive pressure deviation signals and participate in regulation calculations in subsequent regulation cycles.

[0125] Example 2: While keeping other aspects of Example 1 unchanged, the specific implementation also includes a control mechanism to address the issue of transient pressure disturbances during pump unit rotation being misinterpreted as changes in water load, leading to oscillations in the regulation process. Specifically, this includes:

[0126] A pump set rotation status sensing unit is set inside the controller. The pump set rotation status sensing unit is used to distinguish between the pump set rotation stage and the normal constant pressure regulation stage at the control logic level.

[0127] When the controller detects that the preset pump switching conditions are met and executes the pump group rotation command, a rotation status flag is generated inside the controller. The rotation status flag is used to indicate that the current pressure sensor input value is superimposed with transient pressure disturbances introduced by pump group switching.

[0128] During the effective period of the rotation state flag, the controller switches the regulation interpretation logic of the pressure sensor input value and constrains the participation of pressure deviation in the regulation calculation, so that pressure changes during the rotation phase are not included in the regulation output calculation as water load changes. Specifically, the constraint process includes freezing the cumulative update of pressure deviation in the regulation memory unit, preventing pressure fluctuations caused by pump start-up / shutdown and pipeline inertia during the rotation phase from directly participating in the frequency regulation calculation, thereby avoiding misjudging rotation disturbances as water load changes.

[0129] The controller monitors the rate of pressure change and determines whether it has fallen back to the preset threshold range. If it falls back to the preset threshold range, it determines that the pump rotation process has ended and automatically clears the rotation status mark after the determination is completed. Then it restores the interpretation logic of the pressure sensor input value under the normal constant pressure regulation stage.

[0130] The controller's logic for interpreting the pressure sensor input value switching includes:

[0131] The controller switches the system operating state from normal constant pressure regulation state to pump group rotation control state in its built-in internal state machine.

[0132] The state transition is triggered by one or more of the following: pump running time count, pump start-stop count, or pump group rotation.

[0133] After entering the pump set rotation control state, the controller limits the generation path of the adjustment output, locks the variable frequency output command value corresponding to the rotation trigger time, and sends the variable frequency output command value as a fixed output to the frequency converter during the duration of the pump set rotation control state. During this period, the variable frequency output command value is not recalculated based on the real-time collected pressure sensor input value. The variable frequency output command value refers to the target operating frequency setpoint generated by the controller and sent to the frequency converter within the current control cycle, used to instruct the frequency converter to output a drive signal at the corresponding frequency.

[0134] It should be noted that the generation path of the adjustment output is limited, specifically including:

[0135] During normal constant pressure operation, the output adjustment generation path typically includes:

[0136] The system collects real-time pressure signals, calculates pressure deviations, calls the adjustment memory unit to perform integration and calculations, generates frequency adjustment values, superimposes them onto the current frequency reference, forms frequency conversion output commands, and sends them to the frequency converter.

[0137] After entering the pump set rotation control state, the controller executes the following logic:

[0138] In the internal state machine, the system operating state is switched to the pump set rotation control state, in which:

[0139] Calling the pressure deviation-based adjustment calculation module is prohibited, adjusting the memory unit update is prohibited, adjusting the output to overwrite the frequency converter output register is prohibited, and the output module directly reads a fixed value from the lock register as the frequency converter output.

[0140] After the controller detects that the pump rotation is complete, it switches the system operating status from pump rotation control status back to normal constant pressure regulation status.

[0141] During the state transition, the controller only activates the regulation memory unit corresponding to the newly participating water pump in the frequency conversion regulation, and uses this regulation memory unit as the only state unit currently allowed to participate in the regulation operation.

[0142] When a historical adjustment state exists in the adjustment memory unit, the controller reads and restores that historical adjustment state as the current adjustment initial state.

[0143] When the historical regulation state is not present in the regulation memory unit, the controller reads the accumulated pressure deviation state value corresponding to the original regulating water pump that was frozen before the rotation occurred. Based on the proportional relationship between the unit frequency pressure response coefficient of the original regulating water pump and the newly participating regulating water pump, the controller performs a proportional conversion on the accumulated pressure deviation state value to obtain an equivalent initial value of accumulated pressure deviation that matches the regulation sensitivity of the newly participating regulating water pump. The controller writes the equivalent initial value of accumulated pressure deviation into the regulation memory unit corresponding to the new water pump, and resumes the cumulative update and regulation calculation of pressure deviation after the writing is completed.

[0144] The proportional conversion is a linear proportional conversion, and its proportionality coefficient is the ratio of the original regulating pump's unit frequency pressure response coefficient to the unit frequency pressure response coefficient of the newly participating regulating pump.

[0145] Example 3: While keeping other aspects of Example 1 unchanged, the specific implementation also includes, for example... Figure 2 The schematic diagram of the constant pressure water supply control system shown includes:

[0146] Please see Figure 3 The diagram shown is the wiring schematic of the electrical cabinet for a constant pressure water supply control system, including:

[0147] The system includes a CPC316 constant pressure water supply controller, an ABB frequency converter, a float valve and relay (ZJ1), three main pumps (M1, M2, M3, 11kW power), one auxiliary pump (M4, 4kW power), control circuits, protection circuits, and alarm circuits.

[0148] It should be noted that the pressure transmitter is installed on the main outlet pipeline to collect the input values ​​of the pipeline network pressure sensor in real time. The controller outputs analog and digital control signals based on this signal to realize pump start-up and shutdown, frequency conversion regulation, power frequency switching, alternating operation, and sleep / wake-up.

[0149] In this embodiment, the 0~20mA pressure transmitter is used as a sliding rheostat and installed on the main outlet water pipe. It outputs a resistance value of 0~400Ω according to the water pressure of the pipe and feeds it back to the CPC316 constant pressure water supply controller. The CPC316 constant pressure water supply controller outputs a 0~20mA current to the ABB frequency converter to control the frequency of the water pump. At the same time, the controller also outputs the start, stop and switching of the main and variable frequency water pumps. As a low current control, a shielded wire is selected for grounding.

[0150] Parameter settings include:

[0151] The parameter settings for the constant pressure water supply controller specifically include:

[0152] SP2=7 (maximum pressure setting).

[0153] PROP=14 (proportional band).

[0154] INTT=1 (integral time).

[0155] TH=17 (upper frequency duration).

[0156] TL=22 (lower limit frequency duration).

[0157] DB=0.4 (pressure tolerance).

[0158] SLEP=12 (Sleep detection output value).

[0159] TB=25 (sleep delay time).

[0160] SN = PRE (input signal).

[0161] CTRL=PD (Mediation Method).

[0162] FUNC=PF3 (Pump mode).

[0163] OP1=0-20 (control inverter signal).

[0164] OPR = PFB (Auxiliary pump selection).

[0165] STOP = L - F (Pump Stop Rule).

[0166] TCHR=720 (pump change interval).

[0167] OFST=0 (Measurement error correction value).

[0168] The specific parameter settings for the frequency converter include:

[0169] 9902 = Quasi-macro (select to apply macro).

[0170] 1001 = DI1 (Channel Selection).

[0171] 1102=0 (external selection).

[0172] 1103 = AI2 (Given value 1 for selection).

[0173] 1301 = 40 (AI1 lower limit).

[0174] 1302 = 100 (AI1 upper limit).

[0175] The control system employs both manual and automatic control wiring (see...) Figure 3 In the diagram, M1, M2, and M3 are the main pumps (11KW), and M4 is the auxiliary pump (4KW). This control mode is a cyclic soft-start control mode for 3 main pumps and 1 auxiliary pump (controller settings (FUNC=PF3), controller terminals 31, 32, and 33 are set as the frequency converter terminals for the 3 main pumps, controller terminals 34, 35, and 36 are set as the power frequency terminals for the 3 main pumps, and controller terminal 6 is set as the power frequency terminal for the auxiliary pump).

[0176] When there is power, if the water tank has water, the ZJ1 relay in the control system is activated, and the power supply to the control circuit changeover switch is turned on, allowing for both manual and automatic control. When the water tank is empty, the ZJ1 relay is deactivated, the control circuit changeover switch loses power, the water pump cannot be activated, and a water shortage fault alarm is triggered. An operation fault alarm is also triggered when the water pump is overloaded or malfunctions.

[0177] The manual operation process includes: when the changeover switch is in manual mode, the ZJ relay is connected; press the start button SB1 (or SB3, SB5, SB7), KM2 (or KM4, KM6, KM7) is connected, and the water pump M1 (or M2, M3, M4) runs manually; press the stop button SB2 (or SB4, SB6, SB8), and the water pump stops. This can prevent the situation of water supply failure caused by damage to the sensor, constant pressure water supply controller, or frequency converter.

[0178] The automatic operation process includes: when the selector switch is in manual mode, the CPC316 controller is powered on. After setting the controller and inverter parameters, press the controller value increase key to adjust the SV display window to the set pressure "6". At this time, the PV display window reflects the actual pressure value of the water supply pipe. When the actual pressure is less than the set pressure "6", the controller terminal 31 is connected and KM1 is connected. The inverter terminals 10 and 13 are connected, and the frequency converter starts working, that is, the M1 water pump runs at a frequency. When the frequency converter frequency increases from 0HZ to 50HZ, there is a time delay. When the delay time is up, the controller terminal 31 is disconnected and KM1 is de-energized. The inverter terminals 10 and 13 are disconnected and the frequency converter stops, that is, the M1 water pump stops running at a frequency. At this time, the controller terminal 34 is connected and KM2 is connected, and the M1 water pump runs at the power frequency. If the actual pressure is still less than the set pressure "6" after the M1 water pump has been running at the power frequency for a period of time, then the controller terminal 32 will be connected, KM3 will be connected, and the frequency converter terminals 10 and 13 will be connected, and the frequency converter will start working, that is, the M2 water pump will start operating at the frequency. When the frequency converter is between 0 Hz and 50 Hz, and the actual pressure is around the set pressure "6", the M1 water pump will run at the power frequency and the M2 water pump will remain constant between 0 Hz and 50 Hz, thus achieving constant pressure. When water consumption is low in the late evening, the frequency of the M2 inverter drops to the lower limit, the controller disconnects at terminal 34, de-energizing KM2. M1 stops operating at its mains frequency, and the M2 inverter operates between a constant 0Hz and 50Hz. The actual pressure is around the set pressure "6". When the set sleep delay time expires, the controller disconnects at terminal 32, de-energizing KM3. The inverters at terminals 10 and 13 disconnect, stopping the M2 pump's inverter operation. The controller then connects at terminal 6, energizing KM7, and the M4 pump operates at its mains frequency. This allows for pressure stabilization during the nighttime downtime without starting the high-power main pump, thus saving energy and electricity. When water consumption is high in the morning, the sleep delay time expires, activating the controller's sleep mode. The controller disconnects at terminal 6, de-energizing KM7. The M4 pump stops operating at its mains frequency. The controller then connects at terminal 31, energizing KM3. The inverters at terminals 10 and 13 connect, energizing the M2 pump, thus entering automatic control mode. If pump M1 is running, when the pump switching interval is reached, the controller will automatically switch to the next pump to start, i.e., start M2 or M3. The automatic timed pump switching setting improves the average service life of the pumps.

[0179] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0180] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. The selection and detailed description of these embodiments in this specification are intended to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. Any modifications or variations that do not deviate from the structure of the invention or exceed the scope defined by the invention should fall within the protection scope of the invention.

Claims

1. A PLC-free pump set rotation control method based on a constant pressure water supply controller, characterized in that, include: Establish a corresponding adjustment object model for each water pump in the pump group, and configure a uniquely bound adjustment memory unit for each water pump. The adjustment memory unit is used to record the cumulative pressure deviation state formed by the water pump during the constant pressure regulation process. During normal operation, only the regulation memory unit corresponding to the water pump currently participating in frequency conversion regulation is allowed to participate in regulation calculations, while the regulation memory units of the other water pumps remain frozen. When the pump set rotation judgment condition is met, the controller enters the rotation control stage, suspends the update of the regulation memory unit of the current regulating pump, and suppresses the impact of transient pressure disturbances caused by the rotation on the regulation output. After the pump set rotation is completed, only the regulation memory unit corresponding to the newly participating water pump is activated to participate in the regulation calculation. The regulation memory state before the rotation is equivalently mapped according to the regulation object model of the water pump to form the initial regulation state of the new water pump.

2. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 1, characterized in that: The process of establishing a corresponding adjustment object model for each water pump in the pump group is as follows: During the initialization phase, the controller establishes a set of equivalent regulation characteristic parameters for each water pump. The set of equivalent regulation characteristic parameters includes at least the unit frequency pressure response coefficient and the steady-state regulation sensitivity. The specific method for obtaining the pressure response coefficient per unit frequency is as follows: The controller performs the following test procedure when operating with a single pump independently: When the fixed pipeline network is in a stable water use state, the current water pump is the only variable frequency execution object. The output frequency of the frequency converter is adjusted step by step according to the preset step change. At each frequency step, the corresponding steady-state pressure value of the pipeline network is collected. The unit frequency pressure response coefficient of the water pump is calculated by the ratio of the frequency change to the pressure change. The unit frequency pressure response coefficient is used to reflect the adjustment gain characteristics of the water pump under the current pipeline network conditions. The methods for determining steady-state regulation sensitivity specifically include: The controller divides the water pump into different adjustment sensitivity ranges based on the unit frequency pressure response coefficient. The controller constructs a pressure-frequency mapping table for the pump based on the unit frequency pressure response coefficient and the static resistance characteristics of the pipeline network. The pressure-frequency mapping table is used to predict the pressure response under any frequency change. At the same time, dynamic response parameters are introduced, including pressure change delay time, inertial hysteresis and integral cumulative effect. The dynamic characteristics of the pump are modeled as a set of state variables and difference equations, so that the model can simulate the pressure response process of pump start-up, shutdown and frequency conversion regulation during the control process. The controller integrates the pressure-frequency mapping table, dynamic state equation, steady-state regulation sensitivity and historical regulation memory of each pump to form a complete regulation object model, and stores it in the internal parameter storage area with the pump number as the index. Each regulation object model is bound to a unique regulation memory unit.

3. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 1, characterized in that: During normal operation, only the regulation memory unit corresponding to the water pump currently participating in frequency conversion regulation is allowed to participate in regulation calculations, while the regulation memory units of other water pumps remain frozen. The specific process is as follows: During normal operation, the controller marks the pump currently participating in frequency conversion regulation by the pump number and sets its corresponding regulation memory unit to the active state, allowing the regulation memory unit to receive real-time pressure sensor input values ​​from the pressure sensor. Read the pressure sensor input value corresponding to the currently active water pump, compare the pressure sensor input value with the set target pressure, and calculate the pressure deviation; During each control cycle, the controller performs the following steps for the currently active water pump: The corresponding adjustment memory unit of the water pump is invoked to perform cumulative calculation and integral operation on the pressure deviation, and generate the frequency adjustment output of the current control cycle. The generated adjustment output command is sent to the frequency converter to control the change of water pump speed, and at the same time the pressure deviation accumulation status is written into the adjustment memory unit of the pump. Subsequently, the controller sets the regulation memory units corresponding to all pumps in the pump group that are not currently involved in regulation to a frozen state.

4. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 1, characterized in that: The conditions for determining pump unit rotation specifically include: The pump set rotation determination conditions specifically include a combination of one or more of the following conditions. When any one condition is met, the controller determines to enter the pump set rotation control stage. Specifically, these conditions include: rotation determination conditions based on running time, rotation determination conditions based on the number of start-stop cycles, rotation determination conditions based on operating load characteristics, and rotation determination conditions based on operating status. The rotation determination condition based on running time specifically includes: the controller records the cumulative running time of each water pump. When the cumulative running time of the water pump currently participating in the frequency conversion regulation exceeds the preset pump replacement time threshold, the controller determines that the water pump meets the rotation determination condition based on running time. The cumulative running time is based on the controller's internal time base and is only accumulated when the water pump is in the running state. The timing is paused when the pump is stopped, in hibernation, or in a fault state. The rotation determination condition based on the number of start-stop cycles specifically includes: the controller counts the number of start-stop cycles of each water pump, and when the number of start-stop cycles of the water pump currently participating in frequency conversion regulation reaches the preset upper limit of the number of start-stop cycles within the statistical period, the controller determines that the water pump meets the rotation determination condition based on the number of start-stop cycles. The rotation determination condition based on operating load characteristics specifically includes: the controller monitors whether the water pump currently participating in frequency conversion regulation is higher than the preset high frequency threshold within the statistical period according to the operating frequency fed back by the frequency converter. When the continuous operating frequency is higher than the preset high frequency threshold and the continuous operating time exceeds the set duration, the controller determines that the water pump meets the rotation determination condition based on operating load characteristics. The rotation determination condition based on operating status specifically includes: when an abnormal operating state is detected in the water pump currently participating in the frequency conversion regulation, the controller determines that the water pump meets the rotation determination condition based on operating status and switches to other water pumps in advance to undertake the regulation task.

5. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 1, characterized in that: The controller enters the rotation control phase, pausing the update of the regulation memory unit for the currently regulating water pump, specifically including: The controller records the number of the water pump currently participating in the frequency conversion regulation, as well as the accumulated pressure deviation status and the most recent frequency regulation command stored in the regulation memory unit corresponding to that water pump; After recording is completed, the controller sets an update prohibition flag for the regulation memory unit, so that the regulation memory unit will no longer receive new pressure deviation signal inputs during the rotation control phase; The controller retains the frequency adjustment command recorded before the rotation begins as a fixed output and continuously outputs the command to the frequency converter. The controller blocks write operations to the adjustment memory unit.

6. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 1, characterized in that: The suppression of the impact of transient pressure disturbances caused by rotation on the regulated output specifically includes: The transient pressure disturbance refers to the unsteady pressure change in the pipeline network caused by the switching of the execution object during the pump unit rotation process; Specifically, the impact on the regulation output includes pressure disturbances being misidentified as pressure deviations and directly participating in the regulation calculation; The specific inhibition process includes: After determining that the pump set rotation control phase has been entered, the controller sets the update prohibition state for the regulation memory unit corresponding to the currently regulating water pump; The controller locks the frequency adjustment command calculated most recently before the rotation trigger and continuously outputs the command during the rotation control phase. After the pump unit switching is completed and the recovery conditions are met, the controller removes the update prohibition state, allowing the pressure sensor input value to participate in the regulation calculation again.

7. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 1, characterized in that: The process of activating only the regulation memory unit corresponding to the newly regulated water pump to participate in the regulation operation specifically includes: The controller determines the number of the water pump that has completed its rotation and is currently in variable frequency operation, and marks the water pump as the current regulation object. This mark is used to establish a unique correspondence between the regulation object and the regulation memory unit within the controller. The controller clears the update prohibition state set in the rotation control phase, and only unfreezes the adjustment memory unit corresponding to the current adjustment object, so that the adjustment memory unit is restored to the read and write state. The controller keeps the adjustment memory units corresponding to other water pumps in the frozen state. During each adjustment cycle, the controller compares the pressure sensor input value collected by the pressure detection unit with the set target pressure, calculates the pressure deviation, and inputs only the pressure deviation into the adjustment memory unit corresponding to the current adjustment object. Based on the accumulated pressure deviation state and the model of the regulated object stored in the regulation memory unit, the controller calculates a new frequency regulation command and outputs the regulation command to the variable frequency drive unit to control the current speed change of the water pump; After the adjustment calculation is completed, the controller writes the accumulated pressure deviation state formed in this adjustment cycle into the adjustment memory unit.

8. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 2, characterized in that: The process involves equivalently mapping the pre-replacement adjustment memory state based on the adjustment object model of the water pump to form the initial adjustment state of the new water pump. Specific processing conditions are as follows: The controller reads the accumulated pressure deviation state value stored in the regulation memory unit corresponding to the original regulating water pump before the rotation occurs, and uses it as the mapping input reference. The controller calls the adjustment object model parameters corresponding to the original regulating water pump and the new regulating water pump respectively. The controller calculates the mapping coefficient of the regulation memory state according to the proportional relationship between the unit frequency pressure response coefficients of the two water pumps. The mapping coefficient is equal to the ratio of the unit frequency pressure response coefficient of the original regulating water pump to the unit frequency pressure response coefficient of the new regulating water pump. After obtaining the mapping coefficient, the controller multiplies the cumulative pressure deviation state value before the rotation by the mapping coefficient to generate an equivalent cumulative pressure deviation state value that matches the adjustment sensitivity of the new water pump. This equivalent cumulative pressure deviation state value is used as the initial storage content of the new water pump adjustment memory unit. After the write operation is completed, the controller marks the regulation memory unit as initialized and removes the freeze restriction on the regulation memory unit during the rotation control phase.

9. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 2, characterized in that: It also includes a control mechanism to address the issue of transient pressure disturbances during pump unit rotation being misinterpreted as changes in water load, leading to oscillations in the regulation system. Specifically, this includes: A pump group rotation status sensing unit is set inside the controller. The pump group rotation status sensing unit is used to distinguish between the pump group rotation stage and the normal constant pressure regulation stage at the control logic level. When the controller detects that the pump group rotation judgment condition is met and executes the pump group rotation command, a rotation status flag is generated inside the controller. The rotation status flag is used to indicate that the current collected pressure sensor input value is superimposed with transient pressure disturbance introduced by pump group switching. During the period when the rotation status flag is valid, the controller switches the regulation interpretation logic of the pressure sensor input value and constrains the participation of pressure deviation in the regulation calculation, so that pressure changes during the rotation phase are not used as water load changes in the regulation output calculation. The controller monitors the rate of pressure change and determines whether it has fallen back to a preset threshold range to determine the end of the pump rotation process. After the determination is completed, the rotation status mark is automatically cleared, and then the interpretation logic of the pressure sensor input value under the normal constant pressure regulation stage is restored.

10. The method for PLC-free programmable pump group rotation control based on a constant pressure water supply controller according to claim 9, characterized in that: The controller's logic for interpreting the pressure sensor input value switching includes: The controller switches the system operating state from normal constant pressure regulation state to pump group rotation control state in its internal state machine; The state switching is triggered by any one or more of the following: pump running time count, pump start-stop count, or pump group rotation. After entering the pump set rotation control state, the controller limits the generation path of the adjustment output, locks the frequency converter output command value corresponding to the rotation trigger time, and sends the frequency converter output command value as a fixed output to the frequency converter during the continuous pump set rotation control state. During this period, the frequency converter output command value is not recalculated based on the real-time collected pressure sensor input value. After the controller detects that the pump rotation is complete, it switches the system operating status from the pump rotation control state back to the normal constant pressure regulation state. During the state transition process, the controller only activates the regulation memory unit corresponding to the newly participating water pump in the frequency conversion regulation, and uses the regulation memory unit as the only state unit currently allowed to participate in the regulation operation; When a historical adjustment state exists in the adjustment memory unit, the controller reads and restores that historical adjustment state as the current adjustment initial state; When there is no historical regulation state in the regulation memory unit, the controller performs numerical mapping on the regulation state frozen before the rotation based on the regulation object model corresponding to the newly participating water pump, generates an initial regulation state that matches the regulation sensitivity and unit frequency pressure response characteristics of the water pump, and restores the pressure deviation accumulation update and regulation calculation after the mapping is completed.

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