Adaptive fan variable-frequency air volume control method

Abstract

The invention provides a self-adaptive fan variable-frequency air volume control method, and belongs to the field of variable-air-volume air conditioning system air volume control. According to the actual working condition of each area, the required air volume is predicted, the actual air volume is detected, the total required air volume is worked out, and the initial frequency of a fan is obtained by combining a fan characteristic curve; and the initial frequency of the fan is corrected according to a fan frequency correction rule through the difference value between the total required air volume and the total actually-measured air volume and the opening degree condition of a tail end air door, self-adaptive control over the frequency of the fan is achieved, and the most unfavorable air volume requirement of the tail end is considered while the energy-saving effect is achieved.

Description

Technical Field

[0001] The invention relates to the field of air volume control of variable air volume air conditioning systems and provides an adaptive fan variable frequency air volume control method. Background Art

[0002] In large public buildings, variable air volume air conditioners automatically adjust the air volume according to changes in load demand by controlling the fan frequency of the air handling unit and adjusting the opening of the damper and other parameters. At present, the fan frequency conversion control strategy of the variable air volume air conditioning system generally includes fixed static pressure, variable static pressure and total air volume. The fixed static pressure and variable static pressure adjust the fan frequency through the static pressure of the duct, and the total air volume determines the fan frequency through the relationship between the air volume and the fan speed. Several methods have certain effects, but there are also corresponding defects. When the fixed static pressure method is running at partial load, it still maintains a relatively high static pressure setting value, resulting in a waste of fan energy consumption; the variable static pressure method system control is complex and unstable, and it is easy to have insufficient ventilation. The total air volume method is easy to sacrifice the air volume demand of the unfavorable terminal, resulting in local overcooling and overheating, and cannot accurately meet the needs of all areas. Summary of the invention

[0003] In view of the problems existing in the air volume control method of the variable air volume air conditioning system in the background technology, the present invention proposes an adaptive fan variable frequency air volume control method to further optimize the defects of the variable air volume air conditioning system and achieve the purposes of energy saving, comfort and stability.

[0004] The present invention proposes an adaptive fan variable frequency air volume control method, that is, each area predicts the required air volume according to the actual working conditions and detects the actual air volume and the opening of each terminal damper, the required air volume of each area is summed with the measured air volume to obtain the total required air volume and the total measured air volume, and the initial frequency of the fan is calculated by the total required air volume and the fan characteristic curve; the initial frequency of the fan is corrected by the difference between the total required air volume and the total measured air volume to obtain the fan frequency correction value; finally, the fan frequency correction value is optimized according to the terminal damper opening, and finally the fan frequency control value is obtained.

[0005] The method of correcting the fan frequency based on the difference between the required air volume and the measured air volume is as follows: obtain the difference between the required air volume and the measured air volume in real time online, compare the difference with a set threshold (2% of the maximum air volume of the device), and if the result is not within the set threshold, increase or decrease the fan frequency; otherwise, the fan frequency correction value is zero, and finally the fan frequency correction value is obtained.

[0006] The method of optimizing fan frequency by damper opening is as follows: obtain the damper opening of each VAV terminal in real time online, and judge the terminal damper opening less than 80% as low opening, the terminal damper opening between 80% and 95% as moderate opening, and the terminal damper opening greater than 95% as high opening. Judge whether there is a high damper opening, and if so, perform high opening optimization; if not, judge whether there is a suitable damper opening, and if so, do not optimize; if not, perform low opening optimization.

[0007] High opening and low opening optimization rules: Determine the fan frequency control value based on the total number of terminal devices in operation and the number of high and low openings of the damper, that is: fan frequency control value = fan frequency correction value × (1 ± total number of terminal devices in operation × number of high and low openings of the damper %).

[0008] The beneficial effects of the present invention are: combining the significant energy-saving effect of the variable static pressure method and the advantage of the air volume guarantee of the total air volume method, the initial frequency of the fan is determined by the total required air volume, and then the initial frequency of the fan is adjusted and optimized by the difference between the required air volume and the measured air volume and the terminal air door opening, avoiding the problems of the total air volume method being unable to meet the terminal demand and the variable static pressure method being insufficient in ventilation, and being able to achieve the maximum energy-saving operation while meeting the ventilation needs of each area. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The present invention is a flow chart of an adaptive fan variable frequency air volume control method. DETAILED DESCRIPTION

[0010] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0011] The present invention provides an adaptive fan variable frequency air volume control method, which predicts the required air volume in each area working condition and determines the fan frequency control value through triple control logic to achieve energy saving and comfort. Figure 1 As shown below: Each area of ​​the system predicts the required air volume based on the actual working conditions, and detects the actual air volume and the opening of each terminal damper. The required air volume of each area is summed with the measured air volume to obtain the total required air volume and the total measured air volume. The initial frequency of the fan is obtained from the total required air volume and the fan characteristic curve.

[0012] like Figure 1 As shown, the difference between the total required air volume and the total measured air volume is calculated, and the difference is compared with the set threshold. The threshold is set to 2% of the maximum air volume of all devices. If the absolute value of the difference is within the threshold range, the damper opening is corrected; if the absolute value of the difference is not within the threshold range, the fan frequency is corrected. The fan frequency correction value formula is as follows: Fan frequency correction value = (required air volume - measured air volume) / maximum fan air volume × maximum fan speed like Figure 1 As shown, the damper opening of each VAV terminal is judged in real time. If the terminal damper opening is less than 80%, it is judged as a low opening. If the terminal damper opening is between 80% and 95%, it is judged as a moderate opening. If the terminal damper opening is greater than 95%, it is judged as a high opening. It is judged whether there is a high damper opening. If so, high opening optimization is performed; if not, it is judged whether there is a suitable damper opening. If so, no optimization is performed; if not, low opening optimization is performed.

[0013] High opening and low opening optimization rules: Determine the fan frequency control value based on the total number of terminal devices in operation and the number of high and low openings of the damper. The formula is as follows: Fan frequency control value = Fan frequency correction value × (1 ± total number of terminal devices in operation × number of high and low openings of the damper %).

[0014] The above-mentioned embodiments only express the preferred implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. Therefore, the present invention is not limited to the embodiments here, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. An adaptive fan variable frequency air volume control method, characterized in that: Each area predicts the required air volume according to the actual working conditions, and detects the actual air volume and the opening of each terminal damper. The required air volume and the measured air volume of each area are summed to obtain the total required air volume and the total measured air volume. The initial frequency of the fan is obtained from the total required air volume and the fan characteristic curve to achieve feedforward control; the initial frequency of the fan is then corrected by the difference between the total required air volume and the total measured air volume to obtain the fan frequency correction value to achieve feedback control; finally, the fan frequency correction value is optimized according to the terminal damper opening to obtain the fan frequency control value, and finally the adaptive control of the fan frequency is achieved.

2. The adaptive fan variable frequency air volume control method according to claim 1, characterized in that: The method for correcting the initial frequency of the fan by the difference between the required air volume and the measured air volume is as follows: the difference between the required air volume and the measured air volume is obtained online in real time, the difference is compared with a set threshold, and the threshold is set to 2% of the maximum air volume of the terminal device. If the result is not within the set threshold, the fan frequency is increased or decreased; otherwise, the fan frequency correction value is zero, and the fan frequency correction value is obtained.

3. The adaptive fan variable frequency air volume control method according to claim 1, characterized in that: The method for optimizing the fan frequency correction value by the damper opening is as follows: the damper opening of each VAV terminal is obtained online in real time, a terminal damper opening less than 80% is judged as a low opening, a terminal damper opening between 80% and 95% is judged as a moderate opening, and a terminal damper opening greater than 95% is judged as a high opening, and whether there is a high damper opening is judged, and if so, high opening optimization is performed; if not, whether there is a suitable damper opening is judged, and if so, no optimization is performed; if not, low opening optimization is performed.

4. The adaptive fan variable frequency air volume control method according to claim 3, characterized in that: The high opening degree optimization: the fan frequency control value is determined according to the total number of terminal devices in operation and the number of high opening degrees of the damper, that is, the fan frequency control value = fan frequency correction value × (1 + total number of terminal devices in operation × number of high opening degrees of the damper %).

5. The adaptive fan variable frequency air volume control method according to claim 3, characterized in that: The low opening degree optimization: the fan frequency control value is determined according to the total number of terminal devices in operation and the number of low damper opening degrees, that is, the fan frequency control value = fan frequency correction value × (1-total number of terminal devices in operation × number of low damper opening degrees %).

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