A PLC-based active chilled beam air conditioning terminal control system

Abstract

The present invention discloses an active chilled beam air conditioner terminal control system based on PLC, which connects the CPU, digital input and output module DI / DO, analog input and output module AI / AO of the PLC controller with components such as a chilled water pump, a fresh air fan, a frequency converter, an electric water valve, a fresh air valve, and a temperature and humidity sensor, and is matched with a human-machine interface to achieve the purpose of terminal control. The present invention relates to an active chilled beam air conditioner terminal control system based on PLC, which is divided into high and low temperature chilled water units for operation to meet the indoor sensible heat and latent heat load requirements, and can adjust the number of active chilled beams in operation, the fresh air fan, the fresh air unit, and the operating frequency of the chilled water pump according to the actual load size, so as to achieve the purpose of saving the energy consumption of the air conditioning system. In addition, the control system of the present invention is also equipped with system emergency start and stop measures such as anti-condensation alarm and equipment failure alarm to ensure the safety of the chilled beam air conditioner during operation and indoor hygiene and health.

Description

Technical Field

[0001] The present invention relates to the technical field of building ventilation and air-conditioning energy saving, and in particular to a PLC-based active chilled beam air-conditioning terminal control system. Background Art

[0002] At present, the relationship between people's requirements for indoor living environment comfort and building ventilation and air conditioning energy consumption has aroused widespread social concern. This is reflected in: on the one hand, the global demand for indoor cooling is continuing to grow, and on the other hand, the development of building ventilation and air conditioning must comply with current energy-saving and environmental protection policies. Since more than half of the existing buildings are expected to remain for decades, the task of applying emerging HVAC technologies to new buildings or energy-saving renovations of old buildings is urgent.

[0003] As an emerging building ventilation and air conditioning technology, active chilled beams process indoor sensible heat load and latent heat load separately, and are a type of independent temperature and humidity control system. It uses the fresh air on the primary side to induce indoor air to exchange heat with the chilled beam coil, giving full play to the ability of the chilled beam terminal to process latent cooling load, improving the operating efficiency of the air conditioning system, and saving building energy consumption in long-term operation. In addition, its good indoor airflow organization also brings good human thermal comfort. However, considering that the condensation of the chilled beam coil will affect the indoor environmental hygiene, the pressure loss of the induction nozzle of the active chilled beam will increase the wind pressure requirement for the primary fresh air. Therefore, there is still little engineering application experience in active chilled beam air conditioning systems in China, and it mainly focuses on the use of low-temperature chilled water and normal temperature water mixed (mixed water method) to send into the chilled beam coil for cooling. The mixed water method is only suitable for the situation where only a few rooms in the building need to be cooled by chilled beams. For the building rooms with high comfort requirements, that is, the need to use active chilled beam air conditioning in a large area, it is necessary to use separate high and low temperature chillers to meet the cooling requirements.

[0004] The operation of the active chilled beam air conditioning system not only meets the requirements of indoor comfort for personnel, but also ensures that the unit equipment operates at high efficiency to avoid mechanical wear and equipment failure caused by frequent start and stop of multiple devices at the power frequency. In addition, in order to effectively control the indoor hygiene problems caused by condensation on the chilled beam coil, it is also necessary to set an anti-condensation control strategy.

[0005] In summary, it is urgent to optimize the design of the current active chilled beam terminal control system. Summary of the invention

[0006] The technical problem to be solved by the present invention is to address the above-mentioned problem of chilled beam air-conditioning operation, and provide an active chilled beam air-conditioning terminal control system based on PLC, in which high and low temperature chilled water units are arranged to operate in combination to adapt to the indoor sensible heat and latent heat load requirements. The number of operating chilled beams, the operating frequency of the fresh air fan, the primary-side low-temperature chilled water pump and the secondary-side high-temperature chilled water pump can be adjusted according to the actual load size to achieve the purpose of saving energy consumption of the air-conditioning system.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A PLC-based active chilled beam air conditioning terminal control system, wherein the air conditioning equipment comprises a temperature control module, a humidity control module, a fresh air unit and an active chilled beam, wherein the fresh air unit comprises a fresh air unit coil and a fresh air fan, wherein the temperature control module is connected to a plurality of active chilled beams via the fresh air unit and an air supply duct, and wherein the humidity control module is connected to a plurality of active chilled beams via a high-temperature chilled water circulation duct;

[0009] The temperature control module includes a low-temperature chiller, a primary-side low-temperature refrigerated water pump, a low-temperature refrigerated water plate heat exchanger and a secondary-side low-temperature refrigerated water pump. A water inlet and a water outlet are respectively provided on both sides of the low-temperature refrigerated water plate heat exchanger. One side of the low-temperature refrigerated water plate heat exchanger is connected to the low-temperature chiller and the primary-side low-temperature refrigerated water pump through a low-temperature refrigerated water circulation pipeline, and the other side is connected to the secondary-side low-temperature refrigerated water pump and the fresh air unit coil through a low-temperature refrigerated water circulation pipeline.

[0010] The humidity control module includes a high-temperature chiller, a primary-side high-temperature chilled water pump, a high-temperature chilled water plate heat exchanger and a secondary-side high-temperature chilled water pump. A water inlet and a water outlet are respectively provided on both sides of the high-temperature chilled water plate heat exchanger. One side of the high-temperature chilled water plate heat exchanger is connected to the high-temperature chiller and the primary-side high-temperature chilled water pump through a high-temperature chilled water circulation pipeline, and the other side is connected to the secondary-side high-temperature chilled water pump and multiple active chilled beams through a high-temperature chilled water circulation pipeline.

[0011] A PLC-based active chilled beam air-conditioning terminal control system, whose air-conditioning equipment also includes a plate heat exchanger for mixed water heat exchange, and each side of the plate heat exchanger for mixed water heat exchange is provided with a water inlet and a water outlet; one side of the plate heat exchanger for mixed water heat exchange is connected to a low-temperature chilled water circulation pipeline through a mixed water circulation pipeline, and the other side is connected to a high-temperature chilled water circulation pipeline through a mixed water circulation pipeline.

[0012] One end of the air supply duct is connected to a fresh air fan, and the other end is connected to a plurality of active cooling beams. The fresh air fan and the active cooling beams are provided with electric fresh air valves.

[0013] The high-temperature chilled water circulation pipeline is provided with a fifth electric water valve, a sixth electric water valve and a main electric water valve, and a branch electric water valve is provided between the high-temperature chilled water circulation pipeline and each active chilled beam.

[0014] A first electric water valve and a second electric water valve are arranged between the mixed water circulation pipeline and the low-temperature chilled water circulation pipeline, and a third electric water valve and a fourth electric water valve are arranged between the mixed water circulation pipeline and the high-temperature chilled water circulation pipeline.

[0015] A PLC-based active chilled beam air conditioning terminal control system, whose control equipment includes a CPU of a PLC controller, a digital input / output module DI / DO, an analog input / output module AI / AO, a sensor and a frequency converter. The CPU of the PLC controller is electrically connected to the digital input / output module DI / DO and the analog input / output module AI / AO. The digital input / output module DI / DO and the analog input / output module AI / AO are electrically connected to a chilled water pump, a fan, an electric water valve, a fresh air valve, a sensor and a frequency converter. The specific model of the PLC controller is Mitsubishi FX 3U -64MR CPU, model FX 2N -8AD AD module and model FX 3U -4DA DA module, the sensors include a chilled beam coil surface temperature sensor, a room temperature sensor, and a room humidity sensor.

[0016] The frequency converter is connected to the fresh air fan in the fresh air unit, and the operating frequency of the fresh air fan is adjusted by the frequency converter.

[0017] Beneficial effects of the present invention:

[0018] (1) The present invention provides high- and low-temperature chillers for operation in combination to meet the indoor sensible heat and latent heat load requirements. The number of active chilled beams in operation and the operating frequency of the fresh air fan and chilled water pump can be adjusted according to the actual load, thereby achieving the purpose of saving energy consumption of the air conditioning system.

[0019] (2) The terminal control system of the present invention is also equipped with system emergency start-stop measures such as anti-condensation alarm and equipment failure alarm to ensure the safety of the chilled beam air conditioner during operation and indoor hygiene and health. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the active chilled beam air conditioning system of the present invention;

[0021] Figure 2 This is a schematic diagram of the equipment connection of the active chilled beam air conditioning terminal control system of the present invention;

[0022] Figure 3This is a working principle diagram of the active chilled beam air conditioner of the present invention under normal working conditions;

[0023] Figure 4 This is a working principle diagram of the active chilled beam air conditioner high temperature chiller unit of the present invention when it fails;

[0024] In the figure: 1. low temperature chiller; 2. high temperature chiller; 3. fresh air unit; 4. fresh air unit coil; 5. fresh air fan; 6. first active chilled beam; 7. second active chilled beam; 8. third active chilled beam; 9. fourth active chilled beam; 10. first chilled beam coil surface temperature sensor; 11. second chilled beam coil surface temperature sensor; 12. third chilled beam coil surface temperature sensor; 13. fourth chilled beam coil surface temperature sensor; 14. first electric fresh air valve; 15. second electric fresh air valve; 16. third electric fresh air valve; 17. fourth electric fresh air valve; 18. first branch electric water valve; 19. second branch electric water valve; 20. third branch electric water valve Electric water valve; 21. Fourth branch electric water valve; 22. Main electric water valve; 23. First electric water valve; 24. Second electric water valve; 25. Third electric water valve; 26. Fourth electric water valve; 27. Fifth electric water valve; 28. Sixth electric water valve; 29. ​​Primary side low-temperature chilled water pump; 30. Primary side high-temperature chilled water pump; 31. Secondary side low-temperature chilled water pump; 32. Secondary side high-temperature chilled water pump; 33. Low-temperature chilled water plate heat exchanger; 34. High-temperature chilled water plate heat exchanger; 35. Plate heat exchanger for mixed water heat exchange; 36. Room temperature sensor; 37. Room humidity sensor; 38. Refrigeration room; 39. First inverter; 40. Second inverter. DETAILED DESCRIPTION

[0025] In order to better explain the present invention, the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example: See Figure 1-4 .

[0027] like Figure 1 As shown, a PLC-based active chilled beam air conditioning terminal control system includes a temperature control module, a humidity control module, a fresh air unit 3 and an active chilled beam, the fresh air unit 3 includes a fresh air unit coil 4 and a fresh air fan 5, the temperature control module is connected to multiple active chilled beams through the fresh air unit 3 and the air supply duct, and the humidity control module is connected to multiple active chilled beams through a high-temperature chilled water circulation duct;

[0028] The temperature control module includes a low-temperature chiller 1, a primary-side low-temperature chilled water pump 29, a low-temperature chilled water plate heat exchanger 33 and a secondary-side low-temperature chilled water pump 31. The low-temperature chilled water plate heat exchanger 33 has a water inlet and a water outlet on both sides. One side of the low-temperature chilled water plate heat exchanger 33 is connected to the low-temperature chiller 1 and the primary-side low-temperature chilled water pump 29 through a low-temperature chilled water circulation pipeline, and the other side is connected to the secondary-side low-temperature chilled water pump 31 and the fresh air unit coil 4 through a low-temperature chilled water circulation pipeline;

[0029] The humidity control module includes a high-temperature chiller 2, a primary-side high-temperature chilled water pump 30, a high-temperature chilled water plate heat exchanger 34 and a secondary-side high-temperature chilled water pump 32. The high-temperature chilled water plate heat exchanger 34 is provided with a water inlet and a water outlet on both sides. One side of the high-temperature chilled water plate heat exchanger 34 is connected to the high-temperature chiller 2 and the primary-side high-temperature chilled water pump 30 through a high-temperature chilled water circulation pipeline, and the other side is connected to the secondary-side high-temperature chilled water pump 32 and multiple active chilled beams through a high-temperature chilled water circulation pipeline.

[0030] A PLC-based active chilled beam air-conditioning terminal control system also includes a plate heat exchanger 35 for mixed water heat exchange, and a water inlet and a water outlet are respectively provided on both sides of the plate heat exchanger 35 for mixed water heat exchange; one side of the plate heat exchanger 35 for mixed water heat exchange is connected to a low-temperature chilled water circulation pipeline through a mixed water circulation pipeline, and the other side is connected to a high-temperature chilled water circulation pipeline through a mixed water circulation pipeline.

[0031] An active chilled beam air conditioning terminal control system based on PLC, the operating system principle is as follows:

[0032] Under normal operating conditions, the low-temperature chiller 1 generates low-temperature chilled water, and the primary-side low-temperature chilled water and the secondary-side low-temperature chilled water inlet and outlet water temperatures (7 / 12°C) are heat exchanged through the primary-side low-temperature chilled water pump 29 and the secondary-side low-temperature chilled water pump 31, respectively, and the secondary-side chilled water is transported to the fresh air unit coil 4 of the fresh air unit 3 through the secondary-side low-temperature chilled water pump 31;

[0033] The high-temperature chiller 2 generates high-temperature chilled water, and the primary-side high-temperature chilled water and the secondary-side high-temperature chilled water inlet and outlet water temperatures (16 / 19° C.) are heat exchanged through the primary-side high-temperature chilled water pump 30 and the secondary-side high-temperature chilled water pump 32, respectively. The secondary-side chilled water is transported to the cooling coils of the first active chilled beam 6, the second active chilled beam 7, the third active chilled beam 8, and the fourth active chilled beam 9 through the secondary-side high-temperature chilled water pump 32;

[0034] After the primary air (fresh air) is cooled by the coil 4 of the fresh air unit, it is sent to the first active chilled beam 6, the second active chilled beam 7, the third active chilled beam 8 and the fourth active chilled beam 9 respectively through the fresh air fan 5. After being sprayed out through the nozzle, negative pressure is formed in the mixing chamber of the active chilled beam, inducing the secondary air in the room 38 to exchange heat with the coil in the active chilled beam. After that, the primary air and the secondary air are mixed in the mixing chamber of the active chilled beam and sent to the room 38 from the air outlet of the active chilled beam.

[0035] At the front end of the cooling coils of the first active chilled beam 6, the second active chilled beam 7, the third active chilled beam 8 and the fourth active chilled beam 9, a main electric water valve 22, a first branch electric water valve 18, a first branch electric water valve 19, a first branch electric water valve 20 and a first branch electric water valve 21 are respectively provided, which are used for the main on-off and branch on-off of high-temperature chilled water respectively.

[0036] A first electric fresh air valve 14, a second electric fresh air valve 15, a third electric fresh air valve 16 and a first electric fresh air valve 17 are respectively provided between the fresh air unit 3 and the first active chilled beam 6, the second active chilled beam 7, the third active chilled beam 8 and the fourth active chilled beam 9, which are respectively used for turning on and off the fresh air of each branch.

[0037] The first electric water valve 23, the second electric water valve 24, the third electric water valve 25, the fourth electric water valve 26, the fifth electric water valve 27, and the sixth electric water valve 28 are valves used for water path switching when the high-temperature chiller 2 fails; when the high-temperature chiller 2 operates normally, the first electric water valve 23, the second electric water valve 24, the fourth electric water valve 25, and the sixth electric water valve 28 are closed, and the third electric water valve 26 and the fifth electric water valve 27 are opened; when the high-temperature chiller 2 fails, the low-temperature chiller 1 operates alone and shares a part of the chilled water and mixes with the normal temperature water at the same time, providing high-temperature chilled water for the first active chilled beam 6, the second active chilled beam 7, the third active chilled beam 8, and the fourth active chilled beam 9, at which time the first electric water valve 23, the second electric water valve 24, the fourth electric water valve 25, and the sixth electric water valve 28 are opened, and the third electric water valve 26 and the fifth electric water valve 27 are closed.

[0038] like Figure 2 As shown, a PLC-based active chilled beam air conditioning terminal control system, whose control equipment includes a PLC CPU, a digital input / output module DI / DO, an analog input / output module AI / AO, a sensor and a frequency converter, the CPU of the PLC controller is electrically connected to the digital input / output module DI / DO and the analog input / output module AI / AO, and the digital input / output module DI / DO and the analog input / output module AI / AO are electrically connected to a chilled water pump, a fan, an electric water valve, a fresh air valve, a sensor and a frequency converter;

[0039] The control equipment specifically includes Mitsubishi FX 3U -64MR CPU, model FX 2N -8AD AD module and model FX 3U -4DA DA module, the sensors include a chilled beam coil surface temperature sensor, a room temperature sensor 36, and a room humidity sensor 37.

[0040] With the PLC controller FX 3U -64MR is used as a reference, and the digital input module DI includes: the start and stop X0 of the main power supply, the start and stop (X1~X4) of the first active chilled beam 6, the second active chilled beam 7, the third active chilled beam 8, and the fourth active chilled beam 9, the fault signal X5 of the fresh air fan 5, the fault signal X6 of the secondary side low-temperature chilled water pump 31, the fault signal X7 of the secondary side high-temperature chilled water pump 32, the fault signal X10 of the second inverter 40 of the fresh air fan 5, the fault signal X11 of the first inverter 39 of the secondary side high-temperature chilled water pump 32, and the fault signal X12 of the high-temperature chiller 2.

[0041] The PLC controller FX 3U -64MR is used as the reference, and the digital output module DO includes: the first electric fresh air valve 14 signal Y0, the second electric fresh air valve 15 signal Y1, the third electric fresh air valve 16 signal Y2, and the fourth electric fresh air valve 17 signal Y3; the first branch electric water valve 18 signal Y4, the second branch electric water valve 19 signal Y5, the third branch electric water valve 20 signal Y6, and the fourth branch electric water valve 21 signal Y7; the main electric water valve 22 signal Y10, the first electric water valve 23 signal Y23, The second electric water valve 24 signal Y24, the third electric water valve 25 signal Y25, the fourth electric water valve 26 signal Y26, the fifth electric water valve 27 signal Y27, the sixth electric water valve 28 signal Y28, the operating terminal signal (Y12~Y17) of the second inverter 40 of the fresh air fan 5, the operating terminal signal (Y21~Y22) of the first inverter 39 of the secondary side high-temperature chilled water pump 32, the operating signal Y11 of the secondary side low-temperature chilled water pump 31 and the condensation alarm indicator light Y20.

[0042] The analog input module FX of the PLC controller 2N -8AD is used as a reference, and the analog input module AI includes: the indoor dry bulb temperature CH1 of the room 38, the indoor relative humidity CH2 and the surface temperatures (CH3-CH6) of the four active chilled beam coils used in the embodiment.

[0043] The analog output module FX of the PLC controller3U -4DA is used as a reference, and the analog output module AO includes: an operating terminal of the first inverter 39 of the secondary side high-temperature chilled water pump 32.

[0044] In summary, a PLC-based active chilled beam air conditioning terminal control system has the following specific control process: press the main power button, then press the corresponding active chilled beam start button and confirm; when just started, the control system will give priority to turning on the fresh air fan 5 and opening the corresponding fresh air valve. When initially turned on, the frequencies of the initial fresh air fan 5 second inverter 40 corresponding to the number of active chilled beams are 50Hz (4 units), 45Hz (3 units), 40Hz (2 units), and 35Hz (1 unit). At the same time, the PLC controller FX 3U - The internal timer of the 64MR starts timing. After 2 minutes, when it is detected that the indoor dew point temperature is lower than 16.7°C or the timer has passed 5 minutes, the branch electric water valve, the main electric water valve and the secondary side high-temperature chilled water pump 32 are opened in sequence. After the secondary side high-temperature chilled water pump 32 is started, the initial inverter frequency corresponding to the inverter of the fresh air fan 5 is adjusted to 40Hz (4 units), 36Hz (3 units), 32Hz (2 units), 28Hz (1 unit), and then multi-stage speed adjustment is performed according to the range of indoor relative humidity;

[0045] The frequency of the secondary side high temperature chilled water pump 32 inverter is determined by the number of active chilled beams initially turned on and the indoor dry bulb temperature. First, the frequency is initially determined to be 40Hz (4 units), 36Hz (3 units), 32Hz (2 units), and 28Hz (1 unit) based on the number of units turned on. After three minutes of turning on, PID adjustment is performed based on the difference between the indoor dry bulb temperature and the set temperature. Combined with the requirements for anti-condensation of the chilled beam coil, under the premise that the relative humidity is below 50%, the frequency is adjusted according to the indoor dry bulb temperature t g and relative humidity Calculate the dew point temperature t d , and read the surface temperature t of each chilled beam coil w , when t d +1.2≤t w ≤t d +1.5, immediately adjust the frequency of the secondary side high temperature chilled water pump 32 to 10Hz, and close each electric water valve and the main electric water valve 22, and wait until t w >t d +1.5, the operating frequency of the secondary side high temperature chilled water pump 32 is adjusted by PID according to the difference between the above dry bulb temperature value and the set value; when t w ≤t d +1.2, immediately close the secondary side high temperature chilled water pump 32 and each electric water valve.

[0046] An active chilled beam air conditioning terminal control system based on PLC, the processing method for the air conditioning system operation failure is as follows:

[0047] When the secondary low-temperature chilled water pump 31 fails, first shut down the secondary low-temperature chilled water pump 31, then shut down the secondary high-temperature chilled water pump 32 and each branch electric water valve, and finally shut down the fresh air fan and each branch electric fresh air valve after a delay of 1 minute;

[0048] When the secondary high-temperature chilled water pump 32 fails, first shut down the secondary high-temperature chilled water pump 32, then shut down the electric water valves of each branch and the secondary low-temperature chilled water pump 31, and finally shut down the fresh air fan 5 (delay 1 minute) and each electric fresh air valve (delay 1 minute);

[0049] When the fresh air fan 5 fails, first shut down the fresh air fan 5, then shut down the secondary low-temperature chilled water pump 31, each branch electric fresh air valve, secondary high-temperature chilled water pump 32, and finally shut down each branch electric water valve;

[0050] When the second frequency converter 40 of the fresh air fan 5 fails, first turn off all output signals related to the second frequency converter 40 of the fresh air fan 5, and then turn off the fresh air fan, the chilled water pump, the fresh air valve, the chilled water pump, and the chilled water valve in order;

[0051] When the inverter of the chilled water pump fails, all signals related to the inverter of the secondary high-temperature chilled water pump 32 are turned off, and then the chilled water valve, fresh air unit (delay of 1 minute), and fresh air valve (delay of 1 minute) are closed in sequence.

[0052] When the user presses the stop button of a single active chilled beam in the above operation process, the control system first reduces the frequency converter of the fresh air unit 5 and the first frequency converter 39 of the secondary side high-temperature chilled water pump 32 to the corresponding frequency, and then closes the corresponding branch electric water valve and electric fresh air valve in sequence;

[0053] When the main power stop button is pressed, the control system first stops the secondary side high-temperature chilled water pump 32 (i.e. cancels the inverter forward signal output), and then closes the branch electric water valves, the secondary side low-temperature chilled water pump 31 (i.e. cancels the inverter forward signal output), the fresh air fan 5 (delay of 1 minute), and the electric fresh air valves (delay of 1 minute) in sequence.

[0054] The reason why the fresh air blower 5 needs to be turned on first to lower the indoor dry-bulb temperature and relative humidity before turning on the secondary-side high-temperature chilled water pump 32 in the above operation process is as follows: first, fully utilize the primary fresh air to remove part of the indoor latent heat, and lower the indoor air dew point temperature by lowering the indoor dry-bulb temperature and relative humidity, so as to ensure that the surface temperature of the chilled beam coil is higher than the indoor air dew point temperature when the secondary-side high-temperature chilled water pump is turned on again. The dew point temperature is calculated by the dry-bulb temperature and relative humidity using the empirical formula as follows:

[0055]

[0056] Where t is the dry bulb temperature in °C, is the relative humidity. The empirical formula (1) is embedded into the PLC controller as a subroutine, and the anti-condensation control program is written by calling it, so as to control the start and stop of the equipment to ensure indoor hygiene and health.

[0057] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A PLC-based active chilled beam air conditioning terminal control system, wherein the air conditioning equipment comprises a temperature control module, a humidity control module, a fresh air unit (3) and an active chilled beam, and wherein: The fresh air unit (3) comprises a fresh air unit coil (4) and a fresh air fan (5); the temperature control module is connected to the plurality of active chilled beams via the fresh air unit (3) and the air supply duct; and the humidity control module is connected to the plurality of active chilled beams via a high-temperature chilled water circulation duct; The temperature control module comprises a low-temperature chiller (1), a primary-side low-temperature refrigerated water pump (29), a low-temperature refrigerated water plate heat exchanger (33) and a secondary-side low-temperature refrigerated water pump (31); the low-temperature refrigerated water plate heat exchanger (33) is provided with a water inlet and a water outlet on both sides respectively; one side of the low-temperature refrigerated water plate heat exchanger (33) is connected to the low-temperature chiller (1) and the primary-side low-temperature refrigerated water pump (29) via a low-temperature refrigerated water circulation pipeline, and the other side is connected to the secondary-side low-temperature refrigerated water pump (31) and the fresh air unit coil (4) via a low-temperature refrigerated water circulation pipeline; The humidity control module comprises a high-temperature chiller (2), a primary-side high-temperature chilled water pump (30), a high-temperature chilled water plate heat exchanger (34) and a secondary-side high-temperature chilled water pump (32); the high-temperature chilled water plate heat exchanger (34) is provided with a water inlet and a water outlet on both sides; one side of the high-temperature chilled water plate heat exchanger (34) is connected to the high-temperature chiller (2) and the primary-side high-temperature chilled water pump (30) via a high-temperature chilled water circulation pipeline, and the other side is connected to the secondary-side high-temperature chilled water pump (32) and a plurality of active chilled beams via a high-temperature chilled water circulation pipeline; the air conditioning equipment also comprises a mixed water heat exchange plate heat exchanger (35); the mixed water heat exchanger (35) is provided with a water inlet and a water outlet on both sides; one side of the mixed water heat exchanger (35) is connected to the low-temperature chilled water circulation pipeline via the mixed water circulation pipeline, and the other side is connected to the high-temperature chilled water circulation pipeline via the mixed water circulation pipeline; A fifth electric water valve (27), a sixth electric water valve (28) and a main electric water valve (22) are arranged on the high-temperature chilled water circulation pipeline in the air conditioning equipment, and a branch electric water valve is arranged between the high-temperature chilled water circulation pipeline and each active chilled beam; A first electric water valve (23) and a second electric water valve (24) are provided between the mixed water circulation pipeline and the low-temperature refrigerated water circulation pipeline, and a third electric water valve (25) and a fourth electric water valve (26) are provided between the mixed water circulation pipeline and the high-temperature refrigerated water circulation pipeline.

2. The PLC-based active chilled beam air conditioning terminal control system according to claim 1, characterized in that: One end of the air supply duct in the air conditioning equipment is connected to a fresh air fan (5), and the other end is connected to a plurality of active cooling beams. The fresh air fan (5) and the active cooling beams are provided with electric fresh air valves.

3. According to the PLC-based active chilled beam air conditioning terminal control system of claim 1, the control device composition includes a CPU of a PLC controller, a digital input / output module DI / DO, an analog input / output module AI / AO, a sensor and a frequency converter, characterized in that: The CPU of the PLC controller is electrically connected to the digital input / output module DI / DO and the analog input / output module AI / AO, and the digital input / output module DI / DO and the analog input / output module AI / AO are connected to the chilled water pump, the fan, the electric water valve, the fresh air valve, the sensor and the inverter; the PLC controller includes a Mitsubishi FX 3U -64MR CPU, model FX 2N -8AD AD module and model FX 3U -4DA DA module, the sensors comprising a chilled beam coil surface temperature sensor, a room temperature sensor (36), and a room humidity sensor (37).

4. The active chilled beam air conditioning terminal control system based on PLC according to claim 3 is characterized in that: The frequency converter is connected to the fresh air fan (5) in the fresh air unit (3), and the operating frequency of the fresh air fan (5) is adjusted by the frequency converter.

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