Variable Differential Pressure Control System Applicable to Primary Pump System of Air Conditioner

Abstract

The invention provides a variable pressure difference control system applicable to an air conditioner first-stage pump system and relates to the field of refrigerating control. The system aims to improve refrigerator power and accuracy of hydraulic balance adjustment, reduce energy consumption and achieve safe and stable operation. The variable pressure difference control system comprises a refrigerator power control device, a first-stage pump variable-frequency control device and a cold water minimum flow control device. The refrigerator power control device controls the power of a refrigerator device according to cold water, water return temperature and cold water flow. The first-stage pump variable-frequency control device is used for computing the opening value of an equivalent valve of a fan coil and carrying out variable-frequency control over a first-stage pump according to the opening values of all cold valves at the tail ends of air conditioners of an air conditioning system, cold water temperature, cold water flow and differential pressure for water return. The cold water minimum flow control device controls a balance pipe backflow valve according to cold water flow. The variable pressure difference control system is used for refrigerator power control of the air conditioning system and the variable-frequency control technology.

Description

technical field [0001] The invention relates to the field of chiller control, in particular to a variable differential pressure control system suitable for a primary pump system of an air conditioner. Background technique [0002] At present, some chillers, especially large-scale central air-conditioning systems, use a first-stage variable frequency pump. [0003] This is due to, as figure 1 As shown, the traditional primary pump system is as follows: including chiller system (i.e. chiller device), primary pump set, water supply pipeline and return pipeline, wherein, the water supply pipeline includes water supply main pipe 5 and is arranged in parallel on the water supply main pipe Multiple water supply pipes 2 on 5, the return water pipeline includes a return water main pipe 6 and a plurality of return water pipes 3 arranged in parallel on the return water main pipe 6, and the chiller system includes multiple chillers 1 arranged in parallel, and the water supply main pipe...

AI Technical Summary

Problems solved by technology

[0006] In the existing chiller power adjustment and chilled water delivery control technology, the chilled water temperature and the differential pressure of the supply and return water are controlled by single-loop feedback, which often ignores the minimum flow limit and protection of the chiller at low loads, while at high loads When the cold water outlet temperature may exceed the limit and be out of control, it cannot meet the quality requirements of the air-conditioning end for cold water; at the same time, the single-loop feedback control is adopted, and the controller will only intervene after the controlled parameters change, and there is a lag in the adjustment This control method will undoubtedly affect the stability of process parameters, and there are various disturbances in the chiller and central air-conditioning system, such as the change of cold water flow and return water temperature will have a greater impact on the change of chiller outlet water temperature The fluctuation of system pressure will also affect the change of cold water flow and then affect the differential pressure of supply and return water. Simply relying on single-loop feedback control cannot effectively solve the problem of process parameter stability, and it will also bring hidden dangers to the safety of system operation.

[0007] In addition, it is unreasonable to use a fixed value control for the differential pressure of the supply and return water. If the differential pressure setting value is too large, there will be energy waste caused by excessive cold water delivery; if it is too small, some thermally unfavorable circuits of the air conditioning system will If there is a problem of insufficient cooling capacity, it cannot meet the comfort requirements

[0008] Furthermore, in the existing variable supply and return water differential pressure setting point control technology, it can only be adapted to the occasion where the cold water valve belongs to the continuously adjustable air-conditioning terminal, but it cannot handle the occasion where the air-conditioning system contains a fan-coil air-conditioning type

[0009] To sum up, in the above-mentioned existing chiller power adjustment and cold water delivery control air-conditioning load adjustment technologies, the above-mentioned technologies all have poor accuracy of chiller power and cold water delivery hydraulic balance adjustment, poor safety and stability, and difficulty in meeting the most unfavorable conditions. The issue of circuit comfort requirements

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