All-variable-frequency secondary constant pressure water supply system

Abstract

The utility model relates to a kind of full frequency conversion secondary constant pressure water supply systems, including pressure sensing module, control hub module, man-machine interaction module and execution mechanism module;Pressure sensing module includes main pressure sensor and spare pressure sensor and is installed at the intersection of vertical section and horizontal section of pipe network;Control hub module includes programmable logic controller PLC and redundancy communication bus, programmable logic controller PLC built-in fuzzy PID control algorithm module and energy efficiency optimization database module, and communicate with execution mechanism by MODBUS-RTU protocol;Execution mechanism module includes multiple water pumps and vector control frequency converter, and the output end of vector control frequency converter is provided with LC filter circuit;When system runs, programmable logic controller PLC dynamically adjusts the output frequency of vector control frequency converter according to pressure sensing signal and maintains pipe network pressure within preset range fluctuation.

Description

Technical Field

[0001] This utility model relates to the field of system control technology, and in particular to a fully variable frequency secondary constant pressure water supply system. Background Technology

[0002] Traditional secondary constant pressure water supply systems employ a hybrid control method combining variable frequency and fixed frequency pumps. The working principle is that when the variable frequency pump's water supply is insufficient, a fixed frequency pump is added; if that's still insufficient, another fixed frequency pump is added until the required pressure is met. The disadvantages of this method are that adding or removing pumps causes unstable water pressure, with large fluctuations (±0.05MPa), potentially leading to short-term water outages on the highest floors and malfunctions of water heaters, especially frequent fluctuations in water temperature. Furthermore, the water hammer effect during pump switching is significant, directly reducing the lifespan of the pipe network and increasing maintenance costs.

[0003] Therefore, it is necessary to design a new control scheme to address the shortcomings of traditional control methods. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a fully variable frequency secondary constant pressure water supply system, which can effectively solve the aforementioned problems.

[0005] To achieve the above requirements, the technical solution adopted by this utility model to solve its technical problem is as follows:

[0006] A fully variable frequency secondary constant pressure water supply system is provided, including a pressure sensing module, a control center module, a human-machine interaction module, and an actuator module;

[0007] The pressure sensing module includes a main pressure sensor and a backup pressure sensor; and is installed at the intersection of the vertical and horizontal sections of the pipeline network to collect pressure signals within a preset range in real time.

[0008] The control center module includes a programmable logic controller (PLC) and a redundant communication bus. The PLC has a built-in fuzzy PID control algorithm module and an energy efficiency optimization database module, and communicates with the actuator through the MODBUS-RTU protocol.

[0009] The actuator module includes multiple water pumps and matching vector control frequency converters. Each vector control frequency converter is equipped with an LC filter circuit at its output terminal. When the system is running, the programmable logic controller (PLC) dynamically adjusts the output frequency of the vector control frequency converters according to the pressure sensing signal and maintains the pipeline pressure within a preset range.

[0010] The fully variable frequency secondary constant pressure water supply system of this utility model includes a fuzzy PID control algorithm module that includes a pressure change rate prediction submodule. When a pressure change rate > 0.03 MPa / s is detected, the system automatically switches to fuzzy control mode.

[0011] The fully variable frequency secondary constant pressure water supply system of this utility model includes an energy efficiency optimization database module that stores the efficiency curve parameters of each water pump in the 20%-100% load range, and a control center module that selects the optimal pump group combination based on real-time flow demand.

[0012] The fully variable frequency secondary constant pressure water supply system of this utility model includes the following selection criteria for the optimal pump group combination: current energy efficiency ratio > 0.85, cumulative running time deviation < ±5%, and remaining maintenance cycle > 200 hours.

[0013] The fully variable frequency secondary constant pressure water supply system of this utility model adopts a dual CAN bus architecture for the redundant communication bus, and automatically switches to the backup bus within 50ms when the main bus fails.

[0014] The fully variable frequency secondary constant pressure water supply system of this utility model includes a frequency synchronization compensation link between multiple vector control frequency converters. When a new water pump is connected, the output frequency of the operating vector control frequency converter is adjusted at a slope of 0.5 Hz / second.

[0015] The fully variable frequency secondary constant pressure water supply system of this utility model, wherein the LC filter circuit is composed of a common mode inductor L1 and a safety capacitor C1, and the harmonic distortion rate THD < 3%.

[0016] The fully variable frequency secondary constant pressure water supply system of this utility model further includes a pipe burst emergency module, which immediately shuts down all water pumps and activates alarm relays when a pressure drop rate > 0.05MPa / s is detected.

[0017] The fully variable frequency secondary constant pressure water supply system of this utility model includes an alarm relay whose output contacts are connected in parallel to an RS485 communication alarm channel, which simultaneously triggers audible and visual alarms and remote monitoring platform alarms.

[0018] The beneficial effects of this utility model are as follows:

[0019] The pressure sensing module features dual sensors, one for primary and one for backup, deployed at the intersection of vertical and horizontal sections of the pipeline network. These sensors can accurately monitor pressures ranging from 0.1 to 1.6 MPa, eliminating the blind spots of traditional single sensors at the end of pipe sections. This significantly improves control accuracy and greatly reduces the impact of switching processes. Meanwhile, the programmable logic controller (PLC) enables millisecond-level command transmission via the MODBUS-RTU protocol, ensuring a faster control response in the pipeline network. Furthermore, each pump is independently equipped with a vector frequency converter featuring LC filtering, effectively suppressing harmonic interference and ensuring the accuracy and speed of the control system. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the utility model will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the control logic of this utility model. Detailed Implementation

[0022] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] "Multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] Furthermore, the terms indicating orientation, such as "up," "down," "left," "right," "upper end," "lower end," and "longitudinal," are all based on the posture and position of the device or equipment described in this solution during normal use.

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, a clear and complete description will be provided below in conjunction with the technical solutions in the embodiments of this utility model. Obviously, the described embodiments are some, but not all, embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] The preferred embodiment of this utility model is a fully variable frequency secondary constant pressure water supply system, such as... Figure 1 As shown, the system includes a pressure sensing module, a control center module, a human-machine interface module, and an actuator module. The pressure sensing module comprises a main pressure sensor and a backup pressure sensor, installed at the intersection of the vertical and horizontal sections of the pipeline network, for real-time acquisition of pressure signals within a preset range. The control center module includes a programmable logic controller (PLC) and a redundant communication bus. The PLC has a built-in fuzzy PID control algorithm module and an energy efficiency optimization database module, and communicates with the actuators via the MODBUS-RTU protocol. The actuator module includes multiple water pumps and corresponding vector control frequency converters. Each vector control frequency converter has an LC filter circuit at its output. During system operation, the PLC dynamically adjusts the output frequency of the vector control frequency converters based on the pressure sensing signals to maintain the pipeline pressure within a preset range.

[0028] In actual operation, the main and backup sensors of the pressure sensing module are deployed at the intersection of vertical and horizontal sections of the pipeline network, generally at a distance of ≥5 times the pipe diameter (5D when D≥100mm, 10D when D<100mm) from elbows, valves, or pipe diameter changes. This ensures stable fluid flow and avoids pressure measurement distortion caused by eddies. The spacing between the main and backup sensors is 200±50mm, and they are symmetrically installed using tee fittings. This allows for accurate monitoring within a range of 0.1-1.6MPa, eliminating the blind spot of traditional single sensors at the end of pipe sections, significantly improving control accuracy, and greatly reducing the impact effect during switching. The programmable logic controller (PLC) can achieve millisecond-level command transmission via the MODBUS-RTU protocol, ensuring a higher control response speed for the pipeline network. During the control process, each water pump is independently equipped with a vector frequency converter with LC filtering function, which effectively suppresses harmonic interference and ensures the accuracy and speed of the control system.

[0029] The human-machine interaction module is equipped with a touch screen and integrates a pressure curve display area, an energy efficiency analysis interface, and an alarm record window. The touch screen's energy efficiency analysis interface displays the power consumption per unit flow of each pump in real time and automatically generates a daily energy efficiency comparison curve.

[0030] In this embodiment, the fuzzy PID control algorithm module includes a pressure change rate prediction submodule. When a pressure change rate > 0.03 MPa / s is detected, it automatically switches to fuzzy control mode. The switching threshold is determined through pipeline water hammer simulation experiments. In actual simulation, when the pressure change rate ≥ 0.028 MPa / s, the overshoot of traditional PID is > 12%. Therefore, using a threshold of 0.03 MPa / s can ensure that the system responds within 200 ms, and the overshoot is controlled to < 5%.

[0031] In this embodiment, the energy efficiency optimization database module stores the efficiency curve parameters of each water pump within the 20%-100% load range, and the control center module selects the optimal pump group combination based on real-time flow demand. Specifically, the selection criteria for the optimal pump group combination include: current energy efficiency ratio > 0.85, cumulative running time deviation < ±5%, and remaining maintenance cycle > 200 hours (calculated based on bearing life from the water pump manufacturer's maintenance manual). The current energy efficiency ratio... Cumulative runtime deviation This represents the monthly average operating time of pumps of the same model. The database stores pump efficiency curve parameters (e.g., BEP point efficiency ≥ 82%) within the 20%-100% load range, and then matches the optimal pump group combination based on real-time flow demand, effectively extending pump lifespan. Specifically, the energy efficiency optimization database stores flow-efficiency correspondence data tables for each pump within the 20%-100% load range (as shown in Table 1 example), and records the BEP (Best Efficiency Point) parameter (efficiency ≥ 82%) and polynomial fitting equation coefficients (η = aQ). 2 +bQ+c, where η is efficiency, Q is flow rate, and a / b / c are equipment characteristic coefficients).

[0032] Table 1

[0033] 20％ 15.2 68.5 50％ 38.0 81.2 100％ 76 84.1

[0034] In this embodiment, the redundant communication bus adopts a dual CAN bus architecture. When the main bus fails, it automatically switches to the backup bus within 50ms to ensure the continuity of control commands. Specifically, a frequency synchronization compensation link is set between multiple vector control frequency converters. When a new water pump is connected, the output frequency of the running vector control frequency converter is adjusted at a slope of 0.5Hz / second. This design can eliminate switching pressure fluctuations and can basically achieve control with an adjustment accuracy of <0.005MPa.

[0035] In this embodiment, the LC filter circuit is composed of a common-mode inductor L1 and an X2 safety capacitor C1 in a π-type filter circuit, and the harmonic distortion rate THD < 3% to reduce the influence of electromagnetic interference. Specifically, the LC filter circuit adopts a π-type topology, and the parameters are matched according to the power of the frequency converter. The common-mode inductor L1 can be 2-5mH (3.5mH±5% for a 22kW water pump), the X2 safety capacitor C1 can be 10-30μF (22μF / 275VAC for a 22kW water pump), and the damping resistor R1 is 10Ω / 5W (to suppress resonance).

[0036] In this embodiment, the fully variable frequency secondary constant pressure water supply system also includes a pipe burst emergency module. When a pressure drop rate > 0.05 MPa / s is detected (in practice, to avoid misjudgment, the duration is greater than 3 seconds), all water pumps are immediately shut down and an alarm relay is activated. The output contacts of the alarm relay are connected in parallel to the RS485 communication alarm channel, which simultaneously triggers the audible and visual alarm and the remote monitoring platform alarm, realizing synchronous alarm between the local audible and visual alarm and the cloud monitoring platform, and improving the alarm information transmission path.

[0037] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A fully variable frequency secondary constant pressure water supply system, characterized in that, It includes a pressure sensing module, a control center module, a human-machine interaction module, and an actuator module; The pressure sensing module includes a main pressure sensor and a backup pressure sensor; and is installed at the intersection of the vertical and horizontal sections of the pipeline network to collect pressure signals within a preset range in real time. The control center module includes a programmable logic controller (PLC) and a redundant communication bus. The PLC has a built-in fuzzy PID control algorithm module and an energy efficiency optimization database module, and communicates with the actuator through the MODBUS-RTU protocol. The actuator module includes multiple water pumps and matching vector control frequency converters. Each vector control frequency converter is equipped with an LC filter circuit at its output terminal. During system operation, the programmable logic controller (PLC) dynamically adjusts the output frequency of the vector control frequency converters based on the pressure sensing signal and maintains the pipeline pressure within a preset range. The redundant communication bus adopts a dual CAN bus architecture, and automatically switches to the backup bus within 50ms when the main bus fails. A frequency synchronization compensation link is set between multiple vector control frequency converters. When a new water pump is connected, the output frequency of the vector control frequency converter in operation is adjusted at a slope of 0.5 Hz / second. The LC filter circuit consists of a common mode inductor L1 and a safety capacitor C1 X2, and the harmonic distortion rate THD < 3%.

2. The fully variable frequency secondary constant pressure water supply system according to claim 1, characterized in that, The fuzzy PID control algorithm module includes a pressure change rate prediction submodule, which automatically switches to fuzzy control mode when a pressure change rate > 0.03 MPa / s is detected.

3. The fully variable frequency secondary constant pressure water supply system according to claim 2, characterized in that, The energy efficiency optimization database module stores the efficiency curve parameters of each water pump in the 20%-100% load range, and the control center module selects the optimal pump group combination based on real-time flow demand.

4. The fully variable frequency secondary constant pressure water supply system according to claim 3, characterized in that, The selection criteria for the optimal pump set combination include: current energy efficiency ratio > 0.85, cumulative running time deviation < ±5%, and remaining maintenance cycle > 200 hours.

5. The fully variable frequency secondary constant pressure water supply system according to any one of claims 1-4, characterized in that, The aforementioned fully variable frequency secondary constant pressure water supply system also includes a pipe burst emergency module. When a pressure drop rate > 0.05 MPa / s is detected, all water pumps are immediately shut down and the alarm relay is activated.

6. The fully variable frequency secondary constant pressure water supply system according to claim 5, characterized in that, The output contacts of the alarm relay are connected in parallel to the RS485 communication alarm channel, which simultaneously triggers the audible and visual alarms and the remote monitoring platform alarm.

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