CN202530510U - Frequency conversion and voltage transformation control system for centralized water supply - Google Patents

Abstract

The utility model provides a centralized water supply variable frequency variable pressure control system, which includes a water pump, a water supply pipeline, a frequency converter and a pressure sensor. The water supply pipeline is provided with a flow sensor capable of sensing fluid flow and converting it into an available output signal; It includes a PLC controller; the water pump is connected to the PLC controller through a frequency converter, and the flow sensor and the pressure sensor are also respectively connected to the PLC controller. The utility model realizes that the water supply pressure at the user end is basically unchanged no matter in the low water consumption period or the peak water consumption period, the outlet pressure of the system is reduced when the water consumption is small, and the outlet pressure of the system is increased when the water consumption is large, thereby reducing the pressure caused by the pipeline. The loss of water resources caused by too high and the waste of power resources caused by the unreasonable setting of the pump working conditions not only ensure the quality of water supply but also save energy and reduce consumption.

Description

Centralized water supply variable frequency variable pressure control system

technical field

The utility model relates to a water supply equipment, in particular to a centralized water supply frequency conversion and pressure conversion control system.

Background technique

At present, the commonly used water supply scheme in the centralized water supply system in rural areas and small towns is frequency conversion and constant pressure water supply. The frequency conversion constant pressure water supply system consists of a water pump, a frequency converter and a pressure sensor installed at the outlet of the system. When the water supply pressure is lower than the set pressure, the frequency converter increases the power frequency of the water pump to increase the speed of the water pump to increase the water supply pressure; when the water supply pressure is higher than the set pressure, the frequency converter reduces the power frequency of the pump, The speed of the water pump is reduced to reduce the water supply pressure, and the speed of the water pump is adjusted by the frequency converter to stabilize the outlet pressure of the system at the set value.

When the frequency conversion and constant pressure water supply, no matter how the water supply volume of the system changes, the outlet pressure of the system basically remains unchanged. During the peak period of water consumption, as the water supply increases, the flow velocity of the water in the pipeline also increases, resulting in a significant increase in the head loss along the pipeline (the head loss along the pipeline is approximately proportional to the square of the average flow velocity of the pipeline). In this way, the water pressure at the user end drops significantly during the peak period of water consumption, making it difficult to ensure normal water supply. When the water consumption is small, the head loss along the pipeline is much smaller than the outlet pressure of the system, and the high water pressure at the user end leads to increased water loss. At this time, the water pump operates under the condition of small flow and high head, and the efficiency and power factor are low, resulting in waste of power resources. .

Utility model content

Aiming at the above problems in the prior art, the utility model provides a centralized water supply variable frequency variable pressure control system with water supply on demand and stable water pressure.

The utility model is achieved through the following technical solutions:

The centralized water supply variable frequency variable pressure control system includes a water pump, a water supply pipeline, a frequency converter and a pressure sensor. The water supply pipeline is provided with a flow sensor capable of sensing fluid flow and converting it into an available output signal;

The control system also includes the measured value of the pressure sensor and the set value of the outlet pressure of the water supply pipeline calculated by the measured value of the flow sensor, and the output frequency of the inverter is determined by using the difference between the measured pressure value and the set pressure value, and PLC controller for speed control of water pump;

The water pump is connected to the PLC controller through the frequency converter, and the flow sensor and the pressure sensor are also connected to the PLC controller respectively.

The control system also includes a water level sensor arranged in the water storage tank and connected with the PLC controller.

The pressure sensor is arranged near the outlet of the water supply pipeline, and the flow sensor is arranged on the water supply pipeline between the water pump and the pressure sensor.

The water supply pipeline is provided with a check valve to prevent water from flowing backward.

The beneficial effect of the utility model is: through the connection between the flow sensor, the pressure sensor and the PLC controller, the output frequency of the frequency converter is controlled, thereby adjusting and controlling the water pump, so that the outlet pressure of the water supply system changes with the change of the water supply. Make corresponding changes. Whether it is in the low water consumption period or the peak water consumption period, the water supply pressure at the user end can be guaranteed to be basically unchanged, the system outlet pressure will be reduced when the water consumption is small, and the system outlet pressure will be increased when the water consumption is large, thereby reducing the damage caused by excessive pipeline pressure. The loss of water resources and the waste of power resources caused by unreasonable setting of pump working conditions not only ensure the quality of water supply but also save energy and reduce consumption.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Figure 2 is a diagram of the hydraulic performance of the water supply system.

In the figure: 1 is a water pump; 2 is a water supply pipeline; 3 is a frequency converter; 4 is a pressure sensor; 5 is a flow sensor; 6 is a PLC controller; 7 is a water storage tank; 8 is a water level sensor; 9 is a check valve.

Detailed ways

The utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

The utility model provides a centralized water supply variable frequency variable pressure control system, as shown in Figure 1, including a water pump 1, a water supply pipeline 2, a frequency converter 3, and a pressure sensor 4. into a flow sensor 5 with an available output signal. Wherein the pressure sensor 4 is arranged near the outlet of the water supply pipe 2 , and the flow sensor 5 is arranged on the water supply pipe 2 between the water pump 1 and the pressure sensor 4 . The water supply pipeline 2 is also provided with a check valve 9 for preventing water backflow, which is generally arranged on the water supply pipeline 2 between the water pump 1 and the flow sensor 5 .

In addition, the control system of the present utility model also includes a PLC controller 6. The function of the PLC controller 6 is to obtain the setting of the outlet pressure of the water supply pipeline 2 by calculating the measured value of the pressure sensor 4 and the measured value of the flow sensor 5. Value, using the difference between the pressure measured value and the pressure set value to determine the output frequency of the inverter 3, and to control the speed of the water pump 1. In the control system, the water pump 1 is connected to the PLC controller 6 through the frequency converter 3 , and the flow sensor 5 and the pressure sensor 4 are also connected to the PLC controller 6 respectively.

The PLC controller 6 determines the outlet pressure of the system according to the real-time flow rate, and the relationship between the set value of the outlet pressure of the system and the flow rate is shown in curve 2 in FIG. 2 . Among them, curve 1 is the full lift curve of the pump, curve 2 is the variable frequency variable pressure hydraulic curve, and curve 3 is the water resistance curve of the pipeline. The water pressure at the user end is the pressure difference between curve 2 and the water resistance curve 3 of the water supply pipe. Curve 2 is the position of the minimum set pressure Pmin after the curve 3 is translated along the positive direction of the P axis. When the water supply of the system is not greater than Qmax, the water pressure at the user end Stable at Pmin. The actual pressure of the system is fed back to the PLC controller 6 by the pressure sensor 4, and the PLC controller 6 determines the output frequency of the frequency converter 3 according to the difference between the actual pressure and the set pressure to control the speed of the electric pump 1, so that the outlet pressure of the system increases along the Curve 2 changes. This control method is also called proportional integral differential control technology, PID control for short, and is implemented by PLC controller 6, wherein the process variable is the system outlet pressure, the process output is the analog signal to control the output frequency of the inverter, and the set value is the flow rate functions instead of constants.

The control system also includes a water level sensor 8 arranged in the water storage tank 7 and connected to the PLC controller 6 to prevent the water pump 1 from running dry due to too little water in the water storage tank 7 .

The utility model controls the output frequency of the frequency converter 3 through the connection between the flow sensor 5, the pressure sensor 4 and the PLC controller 6, thereby adjusting and controlling the water pump 1, so that the outlet pressure of the water supply system changes with the change of the water supply. Make corresponding changes. Whether it is in the low water consumption period or the peak water consumption period, the water supply pressure at the user end can be basically kept unchanged, the system outlet pressure is reduced when the water consumption is small, and the system outlet pressure is increased when the water consumption is large, thereby reducing the pressure caused by the water supply pipeline 2 being too high The resulting loss of water resources and the waste of power resources caused by the unreasonable setting of the pump 1 working condition not only ensure the quality of water supply but also save energy and reduce consumption.

Claims (4)

1. central water supply variable-frequency variable-voltage control system comprises water pump, water supply line, frequency converter and pressure sensor, it is characterized in that said water supply line is provided with the flow transmitter that can experience fluid flow and convert usable output signal to;

Also comprise measured value in the control system through pressure sensor; And the setting value that calculates the water supply line outlet pressure through the flow transmitter measured value; Utilize the difference of piezometry value and pressure set points to confirm the output frequency of frequency converter, and water pump is carried out the PLC controller of speed regulating control;

Said water pump is connected in the PLC controller through frequency converter, and said flow transmitter also is connected with the PLC controller respectively with pressure sensor.

2. central water supply variable-frequency variable-voltage according to claim 1 control system is characterized in that said control system also comprises to be arranged at the level sensor that is connected with said PLC controller in the storage cistern.

3. central water supply variable-frequency variable-voltage according to claim 1 control system is characterized in that said pressure sensor is located at the nearly exit of water supply line, and said flow transmitter is located on the water supply line between water pump and the pressure sensor.

4. central water supply variable-frequency variable-voltage according to claim 1 is controlled system, it is characterized in that said water supply line is provided with the flap valve that prevents aqueous reflux.

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