CN102135311A - Air conditioning system integral optimized control device - Google Patents

Abstract

The invention provides an overall optimization control device for a central air-conditioning system, the device includes a computer host (101), a weak current control system (102), and a strong current control system (103), wherein the weak current control system (102) and the strong current control system (103) are connected in parallel to the host computer (101) through RS485 communication. The control device of the present invention realizes completely compatible and parallel control with the original central air-conditioning control circuit, and has two modes: local control and remote control, wherein the local mode is suitable for on-site button operation, and the remote mode is suitable for remote computer remote control operation. There are automatic mode and manual mode in the travel mode. In the manual mode, the device can be operated remotely. The automatic mode can realize the fully automatic, trouble-free and optimal operation of the central air conditioning system.

Description

An overall optimization control device for a central air-conditioning system

technical field

The invention relates to the technical field of central air-conditioning energy saving, in particular to an overall optimization control device for a central air-conditioning system.

Background technique

Large-scale central air-conditioning systems generally have more than 30% ineffective energy consumption. In actual operation, the maximum load of the air-conditioning system that operates throughout the year generally does not exceed 10% of the total operating time. Since the selection of air-conditioning equipment is based on the design conditions Definitely, and the air conditioning system works at a load rate below 80% most of the time. The energy saving of the central air-conditioning system has been paid more and more attention by people.

At present, among the central air-conditioning energy-saving technologies, including water pump frequency conversion technology, chilled water system fuzzy control technology, neural network technology and other technologies have been widely used in various central air-conditioning technical transformation projects, and have achieved certain energy-saving effects.

However, the problems in these technologies are that they overemphasize the weight of automatic control technology, ignore the complexity and nonlinearity of the air conditioning system, and only focus on the energy saving of a certain equipment or local small system in the central air conditioning system without considering the overall situation.

The air conditioning system is a whole composed of multiple equipment groups. The frequency conversion of the cooling water pump will inevitably cause the temperature change of the cooling water outlet of the chiller and the cooling tower, which will affect the operating efficiency of the cooling tower and the chiller. Only the frequency converter is used alone. If there is no overall control strategy, even if the cooling water pump has energy-saving effect, the energy consumption of the system will increase instead due to the lack of corresponding control of the chiller and cooling tower. At the same time, the frequency conversion of the chilled water pump will inevitably cause the chilled water outlet temperature of the chiller, the opening of the two-way valve of the end user, and the change of the bypass pipe flow. If the frequency converter is used alone and lacks an overall control strategy, it will inevitably affect the operation of the chiller. efficiency and end-user comfort.

The frequency conversion of water pumps is generally controlled by temperature difference or pressure difference. For frequency conversion control with temperature difference as the feedback signal, if the temperature difference is set too small, it will inevitably cause frequent actions of the frequency converter, resulting in oscillation of the entire air conditioning system; if the temperature difference is set too large, it will reduce the sensitivity of the system to load changes, resulting in Frequency conversion control response lag. However, the frequency conversion control that only uses pressure as the feedback signal, because the pressure signal changes rapidly, and the frequency conversion of the water pump will inevitably cause the change of the end valve, which will cause the change of the system pressure, and finally lead to the frequent action of the frequency converter, resulting in the oscillation of the entire air conditioning system. Therefore, if the control strategy of water pump frequency conversion is improperly selected, it will inevitably affect the stability of the entire system operation, resulting in a decrease in system operation efficiency, thereby increasing system energy consumption and offsetting the energy-saving effect brought by water pump frequency conversion.

Therefore, it is necessary to develop a central air-conditioning system overall optimization control device with stable operation, energy saving and relatively low cost.

Contents of the invention

Aiming at the central air-conditioning system, in order to realize the stable operation of the system and the maximum energy-saving effect, an overall optimization control device for the central air-conditioning system is proposed. The invention is fully compatible with the original central air-conditioning control circuit and controlled in parallel with each other. The control mode is divided into local control mode and remote control mode. The local mode is suitable for on-site button operation, and the remote control mode is suitable for remote computer remote operation. It can be divided into automatic mode and manual mode. In manual mode, the device can be moved remotely. Operation, the automatic mode can realize the automatic, trouble-free and optimal operation of the central air-conditioning system. The functions include: chiller control, cooling water pump frequency conversion control, cooling pump frequency conversion control, cooling tower control and electric valve linkage control; equipment operation priority Setting, divided into manual setting, random setting and timing setting, reasonably allocates the running time of the equipment; the setting of the air conditioner running period can be divided into 8 time periods and weekend time periods; the equipment operating parameter setting, according to the characteristics of the air conditioner, reasonably set the operation of each device Parameters; historical trends, energy consumption comparisons and print reports.

An overall optimization control device for a central air-conditioning system. The device includes a computer host, a weak current control system, and a strong current control system, wherein the weak current control system and the heavy current control system are connected in parallel to the computer host through an RS485 communication interface.

In the overall optimization control device of the central air-conditioning system mentioned above, the weak current control system includes the chiller control system, the refrigeration pump control system, the cooling pump control system, the cooling tower control system, and the electric valve control system, among which the chiller control system, The refrigeration pump group control system, cooling pump group control system, cooling tower group control system, and electric valve group control system are all connected in parallel to the host computer through the RS485 communication interface.

In the above-mentioned overall optimization control device of the central air-conditioning system, the chiller control system implements a control mode that combines group control with dynamic adjustment of the cold water outlet temperature as the air-conditioning load changes. The chiller control system includes temperature and humidity sensors, the first A temperature sensor group, a first analog input module group, a first power sensor group, a first AC intermediate relay group, a first digital input module group, a first DC intermediate relay group and a first digital output module group, Among them, the first temperature sensor group, temperature and humidity sensor, and the first power sensor group are connected in parallel to the first analog input module group through shielded twisted pairs, and the first AC intermediate relay group is connected to the first digital input module group through 220VAC cables , the first DC intermediate relay group is connected to the first digital output module group through a 24VDC cable, the first analog input module group, the first digital input module group, and the first digital output module group are connected in parallel through the RS485 communication interface to the host computer.

In the above-mentioned overall optimization control device of the central air-conditioning system, the control system of the refrigeration pump group realizes a control mode in which "one variable multi-fixed" frequency conversion or all frequency conversion methods are combined with pump group control, and the control signals include refrigeration The temperature difference of supply and return main pipes, the pressure difference of refrigerated water supply and return main pipes, and the load rate of air conditioners. The control system of the refrigeration pump group includes a first flow sensor group, a second temperature sensor group, a second analog input module group, a first pressure sensor, the second power sensor group, the second AC intermediate relay group, the second digital input module group, the second DC intermediate relay group and the second digital output module group, in which the first flow sensor group, the second temperature sensor group, the first differential pressure sensor, and the second power sensor group are connected in parallel to the second analog input module group through shielded twisted-pair wires, the second AC intermediate relay group is connected to the second digital input module group through 220VAC cables, and the second The DC intermediate relay group is connected to the second digital output module group through a 24VDC cable; the second analog input module group, the second digital input module group, and the second digital output module group are connected in parallel to the computer host through the RS485 communication interface.

In the above-mentioned overall optimization control device of the central air-conditioning system, the cooling pump group control system realizes a control mode in which "one variable multiple fixed" frequency conversion or all frequency conversion methods are combined with pump group control, and the control signals include cooling The temperature difference of the supply and return main pipes and the pressure difference of the cooling supply and return main pipes. The control system of the cooling pump group includes a third DC intermediate relay group, a third digital output module group, a third AC intermediate relay group, and a third digital input The module group, the third power sensor group, the third temperature sensor group, the third analog input module group, the second differential pressure sensor and the second flow sensor, wherein the third power sensor group, the third temperature sensor group, the second differential The pressure sensor and the second flow sensor are connected in parallel to the third analog input module group through a shielded twisted pair, the third AC intermediate relay group is connected to the third digital input module group through a 220VAC cable, and the third DC intermediate relay group is connected to the third digital input module group through a 24VDC The cable is connected to the third digital output module group, and the third analog input module group, the third digital input module group, and the third digital output module group are connected in parallel to the host computer via the RS485 communication interface.

In the above-mentioned overall optimization control device of the central air-conditioning system, the cooling tower group control system is a group control of the number of units, and the control signal includes the outlet water temperature of the cooling tower group. The cooling tower group control system includes a fourth DC intermediate relay group, a fourth digital output module group, a fourth AC intermediate relay group, a fourth digital input module group, a fourth electric quantity sensor group and a fourth analog input module group, in which the fourth power sensor group is connected in parallel to the fourth analog input module group through a shielded twisted pair, the fourth AC intermediate relay group is connected to the fourth digital input module group through a 220VAC cable, and the fourth DC intermediate relay group is connected to the fourth digital input module group through The 24VAC cable is connected to the fourth digital output module group, the fourth analog input module group, the fourth digital input module group, and the fourth digital output module group are connected in parallel to the host computer via the RS485 communication interface.

In the above-mentioned overall optimization control device for the central air-conditioning system, the electric valve group control system is in a linkage control mode. The electric valve group control system includes the fifth AC intermediate relay group, the fifth digital input module group, the fifth DC intermediate relay group and the fifth digital output module group, wherein the fifth AC intermediate relay group is connected by a 220VAC cable To the fifth digital input module group, the fifth DC intermediate relay group is connected to the fifth digital output module group through a 24VAC cable, the fifth digital input module group, and the fifth digital output module group are connected in parallel to the RS485 communication interface. host computer.

In the above-mentioned overall optimization control device of the central air-conditioning system, the strong current control system includes the frequency conversion control system of the refrigeration pump group and the frequency conversion control system of the cooling pump group, wherein the frequency conversion control system of the refrigeration pump group and the frequency conversion control system of the cooling pump group are connected through the RS485 communication interface. Parallel connection to the host computer.

In the above-mentioned overall optimization control device for the central air-conditioning system, the frequency conversion control system of the refrigerating pump unit includes a first pre-filter, a first frequency converter, a first post-filter, a first AC contactor group and a first temperature difference controller , wherein the first pre-filter, the first frequency converter, the first post-filter, and the first AC contactor group are connected in series through a three-phase cable, the first frequency converter and the first temperature difference controller are connected in series through a shielded twisted pair, The first frequency converter and the first temperature difference controller are connected in parallel to the host computer via the RS485 communication interface; the cooling pump group frequency conversion control system includes a second AC contactor group, a second post-filter, a second frequency converter, a second The temperature difference controller and the second pre-filter, wherein the second AC contactor group, the second post-filter, the second frequency converter, and the second pre-filter are connected in series through a three-phase cable, the second frequency converter, the second temperature difference control The controllers are connected in series through a shielded twisted pair, and the second frequency converter and the second temperature difference controller are connected in parallel to the host computer through an RS485 communication interface.

The working principle of the present invention: the chiller has a high-efficiency load rate range, through the computer group control of the chiller range, adjust the load rate distribution of the chiller in time, so that each chiller is in the best efficient operating state, saving energy consumption and reduce operating costs; at the same time, in order to ensure the safe operation of the chiller, there is a lower flow limit for both chilled water and cooling water; when the load rate is low and the number of chillers started is large, in order to ensure the safety of the chiller Both are relatively large. At this time, through the group control of the chiller, reducing the number of chillers to start, can effectively reduce the water demand of the chilled water pump and the cooling water pump, and reduce the energy consumption of the pump; the freezing and cooling water of each chiller The electric valve should start and stop following the start of cold water. If the chiller has stopped running, but the electric valve of its freezing and cooling water circuit is not closed, it will cause a large amount of chilled water and cooling water to bypass on the side of the chiller, increasing the ineffective energy consumption of the water pump. Through the travel control of the electric water valve, this part of ineffective energy consumption can be effectively eliminated.

Chilled water system 401 with a bypass valve, when the air-conditioning cold water flow demand is lower than the rated flow rate of one water pump, the group control mode of frequency conversion of one pump has the lowest energy consumption and the largest energy saving; the air-conditioning water flow demand is between 1 and 2 water pumps When the rated flow rate is between the two water pump frequency conversion group control methods, the energy consumption is the lowest and the energy saving is the largest; when the air-conditioning water flow demand is between the rated flow rates of 2 and 3 water pumps, the group control method with 3 water pump frequency conversion has the lowest energy consumption , the most energy-saving; when the air-conditioning water flow demand is between the rated flow of 3 and 4 water pumps, the group control mode of frequency conversion of 4 water pumps has the lowest energy consumption and the largest energy saving; with the increase of the bypass pressure difference setting value, When the load rate is high, the energy consumption gap between the four pump frequency conversion group control methods is reduced. At the same time, the "variable and multi-fixed" frequency conversion method will not cause drastic changes in the energy consumption of power frequency water pumps. Therefore, the frequency conversion control of chilled water pumps should set different frequency conversion distribution intervals according to the air conditioning load rate and load time distribution, and reasonably arrange the number of frequency conversion water pumps to minimize the energy consumption of water pumps and save operating costs.

Compared with the prior art, the beneficial effect of the present invention is that the overall optimization control device of the central air-conditioning system has strong operability, can realize switching between local control and remote control, the remote control is flexible in operation, and has manual and automatic functions. In the remote automatic control mode, coordinate the operating parameters of the central air-conditioning equipment from time to time, find the best control strategy, realize the optimal control of the central air-conditioning equipment, and ensure the safety, stability and energy saving of the central air-conditioning system. sex. Through the remote intelligent control of the chillers, the load rate distribution of the chillers is adjusted in time, so that each chiller is in the best efficient operating state, saving energy and reducing operating costs; reducing the number of chillers to start can effectively reduce the chilled water pump and the water demand of the cooling water pump, reduce the energy consumption of the pump and automatically record the running time of the main engine, realize the centralized group control of multiple units; calculate and control the optimal chilled water outlet temperature; adopt the combination operation mode of one water pump frequency conversion and multiple power frequency The operation effect is less than the investment of all frequency conversion methods, and the operation is stable. The frequency conversion of the cooling water pump realizes the stepless adjustment of the cooling water volume. Cooperating with the number control of the cooling tower, it can not only ensure the energy saving effect of the cooling water system 403, but also ensure the stable operation of the system and effectively reduce the initial investment; for the operation data storage, Provide historical data query and trend display and print reports.

Description of drawings

Fig. 1 is a monitoring structure diagram of a central air-conditioning system overall optimization control device of the present invention.

Fig. 2 is a structural diagram of the weak current control system of the present invention.

Fig. 3 is a structural diagram of the heavy current control system of the present invention.

Figure 4 is a structural diagram of the central air-conditioning equipment.

Fig. 5 is a connection diagram of the central air-conditioning equipment of the central air-conditioning system overall optimization control device of the present invention.

Fig. 6 is a logical structure diagram of the control system of the present invention.

Figure 7 is a comparison diagram of the frequency conversion effect of the variable flow cold water system with a bypass valve under the set pressure difference of 80kPa.

Figure 8 is a comparison diagram of the frequency conversion effect of the variable flow cold water system with a bypass valve under the set pressure difference of 128kPa.

Figure 9 is a comparison diagram of the frequency conversion effect of the variable flow cold water system with a bypass valve under the set pressure difference of 170kPa.

Figure 10 is a power comparison diagram of a single pump with frequency conversion and multiple power frequency operation.

Detailed ways

The implementation of the present invention will be further described below in conjunction with the accompanying drawings, but the implementation and protection scope of the present invention are not limited thereto.

The feature of the present invention is that the control system incorporates ideas such as the physical and mathematical model of the operating characteristics of the central air-conditioning system, artificial intelligence and actual operating experience correction, and the background program of the computer workstation runs the physical and mathematical model in real time to automatically optimize to obtain different loads and different outdoor loads. The optimal operating conditions of the air-conditioning system under environmental and other conditions. According to the on-site debugging results and actual operating experience, the calculation results are revised to improve the control accuracy. Artificial intelligence plays a key role in the load forecasting of the air-conditioning area and the optimization of the control system. sexual effect.

As shown in FIG. 4 , the central air-conditioning equipment described in the overall optimization control device of the central air-conditioning system includes a chilled water system 401 , a water chiller 402 and a cooling water system 403 . The chilled water system 401 is composed of chilled water supply and return pipes, chilled water electric valve 512 , bypass regulation system 511 and chilled pump group 513 . Cooling water system 403 is composed of cooling water supply and return pipes, cooling water electric valve 402 , cooling tower water inlet electric valve 516 , cooling tower water outlet electric valve 517 , cooling tower group 519 and cooling pump group 514 .

As shown in Figure 1, a central air-conditioning system overall optimization control device includes a computer host 101, a weak current control system 102, and a strong current control system 103, wherein the weak current control system 102 and the strong current control system 103 are connected to 101 in parallel through the RS485 communication interface.

As shown in Figure 2, the weak current control system 102 includes a chiller control system 201, a refrigeration pump control system 202, a cooling pump control system 203, a cooling tower control system 204, and an electric valve control system 205, wherein the chiller control system 201, The refrigeration pump control system 202, the cooling pump control system 203, the cooling tower control system 204, and the electric valve control system 205 are all connected in parallel to the host computer 101 through the RS485 communication interface.

As shown in Figure 5, the chiller control system 201 includes a temperature and humidity sensor 528, a first temperature sensor group 529, a first analog input module group 530, a first power sensor group 531, a first AC intermediate relay group 532, a first The digital input module group 533, the first DC intermediate relay group 534 and the first digital output module group 535, wherein the first temperature sensor group 529, the temperature and humidity sensor 528, and the first power sensor group 531 are connected in parallel through shielded twisted pairs Connected to the first analog input module group 530, the first AC intermediate relay group 532 is connected to the first digital input module group 533 via a 220VAC cable, and the first DC intermediate relay group 534 is connected to the first digital output via a 24VDC cable The module group 535 , the first analog input module group 530 , the first digital input module group 533 , and the first digital output module group 535 are connected in parallel to the host computer 101 via the RS485 communication interface. The refrigeration pump group control system 202 includes a first flow sensor group 519, a second temperature sensor group 520, a second analog input module group 521, a first differential pressure sensor 522, a second electric quantity sensor group 523, a second AC The intermediate relay group 524, the second digital input module group 525, the second DC intermediate relay group 526 and the second digital output module group 527, wherein the first flow sensor group 519, the second temperature sensor group 520, the first differential pressure The sensor 522 and the second power sensor group 523 are connected in parallel to the second analog input module group 521 through a shielded twisted pair, the second AC intermediate relay group 524 is connected to the second digital input module group 525 through a 220VAC cable, and the second DC The intermediate relay group 526 is connected to the second digital output module group 527 via a 24VDC cable; the second analog input module group 521, the second digital input module group 525, and the second digital output module group 527 are connected in parallel via the RS485 communication interface To the host computer 101. The cooling pump group control system 203 includes a third DC intermediate relay group 536, a third digital output module group 537, a third AC intermediate relay group 538, a third digital input module group 539, and a third power sensor group 540 , the third temperature sensor group 541, the third analog input module group 542, the second differential pressure sensor 543 and the second flow sensor 544, wherein the third power sensor group 540, the third temperature sensor group 541, the second differential pressure sensor 543. The second flow sensor 544 is connected in parallel to the third analog input module group 542 through a shielded twisted pair, the third AC intermediate relay group 538 is connected to the third digital input module group 539 through a 220VAC cable, and the third DC intermediate relay group Group 536 is connected to the third digital output module group 537 via a 24VDC cable, the third analog input module group 542, the third digital input module group 539, and the third digital output module group 537 are connected in parallel to the computer via the RS485 communication interface Host 101. The cooling tower group control system 204 includes a fourth DC intermediate relay group 545, a fourth digital output module group 546, a fourth AC intermediate relay group 547, a fourth digital input module group 548, a fourth power sensor group 549 and The fourth analog input module group 550, wherein the fourth power sensor group 549 is connected in parallel to the fourth analog input module group 550 through a shielded twisted pair, and the fourth AC intermediate relay group 547 is connected to the fourth digital input module group through a 220VAC cable Module group 548, the fourth DC intermediate relay group 545 is connected to the fourth digital output module group 546 via 24VAC cables, the fourth analog input module group 550, the fourth digital input module group 548, the fourth digital output module group The 546 is connected in parallel to the host computer 101 via the RS485 communication interface. The electric valve group control system 205 includes a fifth AC intermediate relay group 553, a fifth digital input module group 554, a fifth DC intermediate relay group 551 and a fifth digital output module group 552, wherein the fifth AC intermediate relay Group 553 is connected to the fifth digital quantity input module group 554 through 220VAC cables, the fifth DC intermediate relay group 551 is connected to the fifth digital quantity output module group 552 through 24VAC cables, the fifth digital quantity input module group 554, the fifth digital quantity The output module group 552 is connected in parallel to the host computer 101 via the RS485 communication interface.

As shown in Figure 3, the strong current control system 103 includes a frequency conversion control system 301 for refrigeration pumps and a frequency conversion control system 302 for cooling pumps, wherein the frequency conversion control system 301 for refrigeration pumps and the frequency conversion control system 302 for cooling pumps are connected in parallel via the RS485 communication interface To the host computer 101. As shown in Figure 5, the frequency conversion control system 301 of the refrigerating pump group includes a first pre-filter 501, a first frequency converter 502, a first post-filter 504, a first AC contactor group 505 and a first temperature difference controller 503, Among them, the first pre-filter 501, the first frequency converter 502, the first post-filter 504, and the first AC contactor group 505 are connected in series through three-phase cables, and the first frequency converter 502 and the first temperature difference controller 503 are connected in series through a shielded double Stranded wires are connected in series, the first frequency converter 502 and the first temperature difference controller 503 are connected in parallel to the host computer 101 through the RS485 communication interface; the cooling pump group frequency conversion control system 302 includes the second AC contactor group 506, the second rear Filter 507, second frequency converter 508, second temperature difference controller 509 and second pre-filter 510, wherein second AC contactor group 506, second post-filter 507, second frequency converter 508, second pre-filter The converter 510 is connected in series through a three-phase cable, the second frequency converter 508 and the second temperature difference controller 509 are connected in series through a shielded twisted pair, and the second frequency converter 508 and the second temperature difference controller 509 are connected in parallel to the host computer through the RS485 communication interface 101.

The above-mentioned sensors collect the physical parameters of each equipment operation and convert them into standard voltage and current signals. The first temperature difference controller 503 collects the temperature difference parameters of the cold water supply and return water main pipes, and outputs the standard voltage and current to the first A frequency converter 502 adjusts the operating frequency parameters of the variable frequency cooling water pump. The second temperature difference controller 509 collects the temperature difference parameters of the cooling supply and return water main pipes. After PID calculation, it outputs standard voltage and current to the second frequency converter 502 to adjust the frequency conversion cooling pump. operating frequency parameters, and at the same time, the host computer 101 can set the control temperature difference of the first temperature difference controller 503 and the second temperature difference controller 509 when in the remote control mode. The temperature and humidity sensor 528 collects outdoor temperature and humidity parameters, the first power sensor group 531 collects the power consumption parameters of each chiller, the first temperature sensor group 529 collects the freezing water inlet and outlet temperature parameters and the cooling inlet and outlet water temperature parameters of each chiller, and the second The second power sensor group 524 collects the power consumption parameters of each cold water pump, the second temperature sensor group 521 collects the temperature parameters of the cold water supply and return main pipes, the first flow sensor group 520 collects the water flow parameters of the cold water main pipes, and the first differential pressure sensor 522 collects For cold water supply and return main pipe differential pressure parameters, the third power sensor group 540 collects power consumption parameters of the cooling water pump, the third temperature sensor group 541 collects cooling water supply and return water main pipe temperature parameters, and the second differential pressure sensor 543 collects cooling water supply parameters. , The differential pressure parameter of the return water main pipe, the power consumption parameter of each cooling tower is collected by the fourth power sensor group 549 .

Each of the above-mentioned input module groups collects the standard voltage and current parameters of each sensor, and inputs them to the host computer 101 through the RS485 communication interface. The host computer performs real-time dynamic analysis and prediction of the user-side cooling load according to the operating parameter information obtained by the sensors, and monitors the operating status and operating time of each device in the central air-conditioning system according to the device operating status information obtained by each digital input module group , and finally through the background logic calculation and analysis of the host computer 101, the high-power control system 103 is controlled through the digital output module group, and then the optimal operation of the central air-conditioning system is controlled.

In this embodiment, the temperature and humidity sensor is a two-wire 4-20mA current output. Powered by 24VDC power supply. Each power sensor group is a two-wire 4 ~ 20mA current output, the specific range depends on the central air-conditioning equipment, powered by 24VDC power supply. Each temperature sensor group is a two-wire 4~20mA current output, with an accuracy of ±1%, and a range of 0~50°C. The specific size depends on the central air-conditioning equipment, and it is powered by a 24VDC power supply. Each flow sensor group is a two-wire 4-20mA current output, the specific range and size are determined according to the central air-conditioning equipment, powered by 24VDC power supply. Each differential pressure sensor group is a two-wire 4-20mA current output, the specific range and size are determined according to the central air-conditioning equipment, powered by DC24V power supply. Each AC intermediate relay group is a 220VAC intermediate relay. Each DC intermediate relay group is a 24VDC intermediate relay.

The implementation of the above-mentioned overall optimization control device for the central air-conditioning system will be described below in conjunction with FIGS. 6-10 and related control modes.

In the overall optimization control device of the central air-conditioning system, the local control and remote control are interlocked. When it is local control, the local operating system realizes the control of the central air-conditioning equipment 104, and the operation status of the central air-conditioning equipment 104 is fed back to the host computer 101 When remote control, the main computer 101 controls the central air-conditioning equipment 104 through the weak current control system 102 system and the strong current control system 103, and the operating parameters of the central air-conditioning equipment 104 are fed back to the main computer 101. The remote control is further divided into manual control mode and automatic control mode. In the manual control mode, the operator directly controls the central air-conditioning equipment 104 by operating the computer host 101 through the weak current control system 102 and the strong current control system 103; the automatic control mode Monitor the central air-conditioning equipment 104 for the computer host 101 through the weak current control system 102 and the strong current control system 103, and perform calculations based on the collected operating parameters of the central air-conditioning equipment 104, and automatically adjust the start-stop, water pump frequency control and loading of the central air-conditioning equipment 104 and uninstall. As shown in Figure 6, the logic structure of the control system adopts the group control and outlet water temperature control strategy for the chiller 402, the number control and single frequency conversion control strategy for the refrigeration pump group 513 and the cooling pump group 514, and the cooling tower group 519 The group control of the number of units and the control strategy of the outlet water temperature are adopted, and the coordinated control is carried out according to the operating parameters of the central air-conditioning equipment 104 .

Each sensor collects the physical parameters of the operation of the central air-conditioning equipment 104 and converts them into standard voltage and current signals, wherein the temperature and humidity sensor 528 collects outdoor temperature and humidity parameters; the first power sensor 531 group collects the power consumption parameters of each chiller; the first temperature The sensor group 529 collects the freezing water inlet and outlet temperature parameters and the cooling water inlet and outlet temperature parameters of each chiller; the second power sensor group 524 collects the power consumption parameters of each cold water pump; the second temperature sensor group 521 collects the cold water supply and return water main pipe temperature Parameters; the first flow sensor group 520 collects the water flow parameters of the chilled water main pipe; the first differential pressure sensor 522 collects the differential pressure parameters of the cold water supply and return water main pipes; the third power sensor group 540 collects the power consumption parameters of the cooling water pump; the third temperature sensor The group 541 collects the temperature parameters of the cooling water supply and return main pipes; the second differential pressure sensor 543 collects the differential pressure parameters of the cooling water supply and return water main pipes; the fourth power sensor group 549 collects the power consumption parameters of each cooling tower.

The first temperature difference controller 503 collects the temperature difference parameters of the cold water supply and return main pipes, outputs standard voltage and current to the first frequency converter 502 after PID calculation, and adjusts the operating frequency parameters of the variable frequency cold water pump; the second temperature difference controller collects the cooling water supply, The temperature difference parameters of the main return water pipe are calculated by PID and output standard voltage and current to the second frequency converter to adjust the operating frequency parameters of the frequency conversion cooling pump. At the same time, the host computer 101 can set the control temperature difference of the first temperature difference controller 503 and the second temperature difference controller in the remote control mode.

Monitoring of main parameters such as chilled water inlet and outlet temperature, cooling water inlet and outlet temperature, main engine power, main engine load rate, single running time and other main parameters of the chiller. The unit with PC interface can directly obtain the operating parameters of the unit through its data communication protocol , and realize remote control; if there is no PC interface or unknown device data communication protocol, the analog quantification of each monitoring parameter is realized through temperature sensor, power sensor and other transmission components, and it is converted into digital signal by data acquisition card or data acquisition module , Realize data communication with the workstation computer through the data network. Use the collected data for analysis and processing, automatically calculate and analyze the load rate and cooling capacity of the unit, and optimize the start-up of the chiller according to the outdoor environment, load rate, enclosure structure and user operating characteristics. In the remote automatic control mode, the operator can set the chilled water outlet temperature and the temperature difference between the inlet and outlet of different chillers at different periods in the manual control mode, and control the opening of the chiller, or it can be automatically controlled by the computer host 101 in the intelligent control mode. Optimizing, selecting the best chilled water outlet temperature and temperature difference between inlet and outlet water of different chillers, and adjusting the number of chillers in operation according to different load ranges, determining the optimal energy-saving operation and management plan, and realizing the optimal performance of chillers in different load ranges combination.

Monitor the main parameters of the chilled water system 401, such as the supply and return water temperature, pressure difference between supply and return water, chilled water flow, bypass flow, refrigeration pump power, and running time of a single refrigeration pump. As well as the running conditions of the host computer, the host computer 101 calculates the actual required minimum flow rate under the minimum energy consumption condition in real time, and then remotely controls the frequency converter of the chilled water pump, using three frequency conversion methods: temperature difference control, pressure difference control, and temperature difference and pressure difference mixed control. In the remote automatic control mode, the operator can set the temperature difference and pressure difference between the inlet and outlet of different chillers at different periods in the manual control mode, and choose the pressure difference control or temperature difference control mode, or it can be controlled by the computer in the intelligent control mode. The main engine 101 automatically seeks the optimization, chooses temperature difference control, pressure difference control or temperature difference and pressure difference mixed control, always chooses the best control temperature difference or pressure difference, uses PID plus control time to control the operating frequency of the water pump, and performs frequency conversion for multiple water pumps. Power frequency control and number control; in the local control mode, the operator can set the temperature difference between the chilled water supply and return water on the temperature difference controller, use PID to control the running frequency of the water pump, and the computer host 101 monitors the operation of the local chilled water pump group.

Monitor the main parameters of the cooling water system 403, such as the supply and return water temperature, the pressure difference between the supply and return water, the cooling water flow rate, the power of the cooling pump, and the running time of a single cooling pump. The computer host 101 calculates the actual required minimum flow rate under the minimum energy consumption condition in real time, and then remotely controls the frequency converter of the cooling water pump, using two frequency conversion methods of temperature difference control and pressure difference control. In the remote automatic control mode, the operator can set the temperature difference and pressure difference between the inlet and outlet of different chillers at different periods in the manual control mode, and choose the pressure difference control or temperature difference control mode, or it can be controlled by the computer in the intelligent control mode. The main engine 101 automatically seeks the optimization, selects the temperature difference control or the pressure difference control, and selects the best control temperature or pressure difference in real time, adopts PID plus control time to control the operating frequency of the water pump, and performs single pump frequency conversion, multiple power frequency control and number control of the water pump ; In the local control mode, the operator can set the temperature difference between the chilled water supply and return water on the temperature difference controller, use PID to control the running frequency of the water pump, and the computer host 101 monitors the operation of the local cooling water pump group.

As shown in Figure 7-9, the comparison of the frequency conversion effect under different set pressure differences of supply and return water, when the water flow is low (less than 100m ³ /h), the energy consumption of frequency conversion with one water pump is the lowest; with the increase of water flow Large (100m ³ /h-200m ³ /h), the energy consumption of 2 pumps with frequency conversion is the lowest; with the increase of water flow (200m ³ /h-300m ³ /h), the energy consumption of 3 water pumps with frequency conversion The lowest; with the increase of water flow (greater than 300m ³ /h), the energy consumption of 4 water pumps with frequency conversion is the lowest; while the energy consumption of 4 water pumps with power frequency operation is the highest. The variable flow operation of the water pump is not only a simple frequency conversion adjustment, but also coordinates and optimizes the water pump control according to the system parameters.

As shown in Figure 10, the power comparison of a single pump with frequency conversion and multiple power frequency parallel operation, when the water pump running at power frequency is running in parallel with the pump running at frequency conversion, the operation of the frequency conversion pump basically has no impact on the operation of the power frequency pump. Parallel operation of variable frequency pumps and power frequency pumps is feasible, the system can run safely and stably and save costs.

Monitoring of main parameters such as the power of the cooling tower group 518, the running time of a single unit, and the temperature difference between the cooling water supply and return water. According to the outdoor air temperature and humidity, the indoor air-conditioning load, and the operation of the host computer, the computer host 101 realizes the cooling tower group 518. control.

It can be seen that the present invention has strong operability, can realize optimal control of various equipment of the central air conditioner, and ensure the safety, stability and energy saving of the central air conditioner system. Through the remote intelligent control of the chiller, the load rate distribution of the chiller is adjusted in time, so that each chiller is in the best efficient operation state, saving energy consumption and reducing operating costs.

Claims (10)

1. central air conditioner system global optimization control device, it is characterized in that described device comprises host computer (101), light-current system (102), heavy-current control system (103), wherein light-current system (102) and heavy-current control system (103) all are connected in parallel to host computer (101) by the RS485 communication interface.

2. central air conditioner system global optimization control device according to claim 1, it is characterized in that light-current system (102) comprises water chilling unit control system (201), refrigerating water pump set control system (202), coolant pump set control system (203), cooling tower set control system (204), motor-driven valve set control system (205), wherein water chilling unit control system (201), refrigerating water pump set control system (202), coolant pump set control system (203), cooling tower set control system (204), motor-driven valve set control system (205) all is connected in parallel to host computer (101) by the RS485 communication interface.

3. central air conditioner system global optimization control device according to claim 2, it is characterized in that water chilling unit control system (201) comprises Temperature Humidity Sensor (528), first sets of temperature sensors (529), the first analog quantity input module group (530), the first electrical quantity sensor group (531), the first AC intermediate relay group (532), the first digital quantity input module group (533), the first direct current auxiliary reclay group (534) and the first digital quantity output module group (535), first sets of temperature sensors (529) wherein, Temperature Humidity Sensor (528), the first electrical quantity sensor group (531) is connected in parallel to the first analog quantity input module group (530) through Shielded Twisted Pair, the first AC intermediate relay group (532) is connected to the first digital quantity input module group (533) through the 220VAC cable, the first direct current auxiliary reclay group (534) is connected to the first digital quantity output module group (535) through the 24VDC cable, the first analog quantity input module group (530), the first digital quantity input module group (533), the first digital quantity output module group (535) is connected in parallel to host computer (101) through the RS485 communication interface.

4. central air conditioner system global optimization control device according to claim 2, it is characterized in that described refrigerating water pump set control system (202) comprises first flow sensor groups (519), second sets of temperature sensors (520), the second analog quantity input module group (521), first differential pressure pick-up (522), the second electrical quantity sensor group (523), the second AC intermediate relay group (524), the second digital quantity input module group (525), the second direct current auxiliary reclay group (526) and the second digital quantity output module group (527), first flow sensor groups (519) wherein, second sets of temperature sensors (520), first differential pressure pick-up (522), the second electrical quantity sensor group (523) is connected in parallel to the second analog quantity input module group (521) through Shielded Twisted Pair, the second AC intermediate relay group (524) is connected to the second digital quantity input module group (525) through the 220VAC cable, and the second direct current auxiliary reclay group (526) is connected to the second digital quantity output module group (527) through the 24VDC cable; The second analog quantity input module group (521), the second digital quantity input module group (525), the second digital quantity output module group (527) are connected in parallel to host computer (101) through the RS485 communication interface.

5. central air conditioner system global optimization control device according to claim 2, it is characterized in that described coolant pump set control system (203) comprises the 3rd direct current auxiliary reclay group (536), the 3rd digital quantity output module group (537), the 3rd AC intermediate relay group (538), the 3rd digital quantity input module group (539), the 3rd electrical quantity sensor group (540), three-temperature sensor group (541), the 3rd analog quantity input module group (542), second differential pressure pick-up (543) and second flow sensor (544), the 3rd electrical quantity sensor group (540) wherein, three-temperature sensor group (541), second differential pressure pick-up (543), second flow sensor (544) is connected in parallel to the 3rd analog quantity input module group (542) through Shielded Twisted Pair, the 3rd AC intermediate relay group (538) is connected to the 3rd digital quantity input module group (539) through the 220VAC cable, the 3rd direct current auxiliary reclay group (536) is connected to the 3rd digital quantity output module group (537) through the 24VDC cable, the 3rd analog quantity input module group (542), the 3rd digital quantity input module group (539), the 3rd digital quantity output module group (537) is connected in parallel to host computer (101) through the RS485 communication interface.

6. central air conditioner system global optimization control device according to claim 2, it is characterized in that, described cooling tower set control system (204) comprises the 4th direct current auxiliary reclay group (545), the 4th digital quantity output module group (546) the 4th AC intermediate relay group (547), the 4th digital quantity input module group (548), the 4th electrical quantity sensor group (549) and the 4th analog quantity input module group (550), wherein the 4th electrical quantity sensor group (549) is connected in parallel to the 4th analog quantity input module group (550) through Shielded Twisted Pair, the 4th AC intermediate relay group (547) is connected to the 4th digital quantity input module group (548) through the 220VAC cable, the 4th direct current auxiliary reclay group (545) is connected to the 4th digital quantity output module group (546) through the 24VAC cable, the 4th analog quantity input module group (550), the 4th digital quantity input module group (548), the 4th digital quantity output module group (546) is connected in parallel to host computer (101) through the RS485 communication interface.

7. central air conditioner system global optimization control device according to claim 2, it is characterized in that, described motor-driven valve set control system (205) comprises the 5th AC intermediate relay group (553), the 5th digital quantity input module group (554), the 5th direct current auxiliary reclay group (551) and the 5th digital quantity output module group (552), wherein the 5th AC intermediate relay group (553) is connected to the 5th digital quantity input module group (554) through the 220VAC cable, the 5th direct current auxiliary reclay group (551) is connected to the 5th digital quantity output module group (552) through the 24VAC cable, the 5th digital quantity input module group (554), the 5th digital quantity output module group (552) is connected in parallel to host computer (101) through the RS485 communication interface.

8. central air conditioner system global optimization control device according to claim 1, it is characterized in that described heavy-current control system (103) comprises refrigerating water pump group frequency-changing control system (301) and coolant pump group frequency-changing control system (302), wherein refrigerating water pump group frequency-changing control system (301), coolant pump group frequency-changing control system (302) are connected in parallel to host computer (101) through the RS485 communication interface.

9. central air conditioner system global optimization control device according to claim 8, it is characterized in that described refrigerating water pump group frequency-changing control system (301) comprises first pre-filter (501), first frequency converter (502), first postfilter (504), the first A.C. contactor group (505) and first differential temperature controller (503), first pre-filter (501) wherein, first frequency converter (502), first postfilter (504), the first A.C. contactor group (505) is connected in series through threephase cable, first frequency converter (502), first differential temperature controller (503) is connected in series through Shielded Twisted Pair, first frequency converter (502), first differential temperature controller (503) is connected in parallel to host computer (101) through the RS485 communication interface.

10. central air conditioner system global optimization control device according to claim 8, it is characterized in that described coolant pump group frequency-changing control system (302) comprises the second A.C. contactor group (506), second postfilter (507), second frequency converter (508), second differential temperature controller (509) and second pre-filter (510), the second A.C. contactor group (506) wherein, second postfilter (507), second frequency converter (508), second pre-filter (510) is connected in series through threephase cable, second frequency converter (508), second differential temperature controller (509) is connected in series through Shielded Twisted Pair, second frequency converter (508), second differential temperature controller (509) is connected in parallel to host computer (101) through the RS485 communication interface.

Images