Research On Variable Frequency Control Of Water Pump Based On Variable Pressure Differential Control

With the intensification of modern urban buildings,the control and energy consumption of air conditioning system in buildings are gradually emerging.The expected energy consumption of water pump transportation accounts for about 20%of the total energy consumption of air conditioning,while the actual operation data shows that the energy consumption of water pump transportation accounts for 25-30%of the total energy consumption of air conditioning,which is one of the key points of energy saving at present.For existing buildings air conditioning water system,water pump frequency conversion operation is the main energy saving operation mode,but at the end of the energy conservation significantly differential pressure control in the process,as the change of different end of traffic demand,in the system the most unfavorable user may change,at this time if still use this kind of control mode may cause the most unfavorable owe flow phenomenon in a loop before the end user,it is difficult to meet the needs of the room temperature,and to lower the room comfort.This paper,taking a primary school building of Tianjin as an example,using TRNSYS software set up air conditioner simulation system,the joint of hydraulic pipe network model is established in the MATLAB,the paper analyzes the differential pressure control,based on the proximal under various operating conditions to ensure the most disadvantageous traffic demand at the end of the variable pressure difference control and two phases under variable pressure difference control units,water pumps and terminal equipment energy consumption indicators.The results show that compared with the constant differential pressure operation,the energy saving rate of the pump controlled by variable differential pressure operation can reach13.62%～16.17%,and the energy consumption of the unit and terminal equipment can be ignored.The control differential pressure required by the variable differential pressure control is affected by the comprehensive influence of the load rate and the load distribution.The differential pressure at the control point of the differential pressure shows an upward trend with the increase of the load rate,and the variation of the differential pressure at the control point of the same load rate with the change of the load distribution has a fluctuation range of 2～4.2m H₂O.In view of this,this paper presents a variable pressure difference control strategy by stages,respectively based on the average load rate of the day and hour average load rate changes is put forward according to the date of the classified methods and daily time-sharing phase partition way,order from large to small is:energy consumption of the proximal constant pressure difference control>by date in stages of variable pressure difference control>daily variable pressure difference control in stages of time-sharing>under various operating conditions based on guarantee the worst traffic demand at the end of the proximal variable pressure difference control.