Cooling Machine Group Control System Design And Implementation

In recent years,with the vigorous development of social economy and the rise of high-rise buildings,central air conditioning has been more and more widely used in commercial and civil buildings,and now it has become an indispensable energy operation system in contemporary buildings.Although central air conditioning provides people with a comfortable life,leisure and working environment,it consumes a lot of energy at the cost.With the continuous rise of housing prices in recent years,the number of high-rise buildings is increasing.In order to guarantee the necessary environment of high-rise buildings.the power and number of hvac equipment are also increasing,and its energy consumption is also increasing.According to the survey of American ARI standard and Chinese industry standard JB/t4329-97,less than 10%of the time,the workload of central air-conditioning system is more than 90%,and less than 1/3 of the time,the workload is more than 60%.These data show that the chiller is often in a half-load state and most of the energy is wasted.Since the performance curves of each equipment are not consistent,the energy consumption of the water pump may be higher at the point with the highest operating efficiency of the chiller.It is meaningless to unilaterally pursue the best operating point of each equipment Doing its overall operation management well can bring more objective energy saving space.Considering the current market professional barriers,the main component of the refrigeration machine room system--the refrigeration main machine,the factory usually has its own control system,and the control of other equipment such as water pump and cooling tower is often integrated in the BA system.In the actual operation of the entire machine room,most of the operations are manually set or only do interlocking start and stop.Such a way will cause the response is not timely,control precision is insufficient and other problems,can not meet the requirements of fine management.Therefore,this paper proposes the concept of group control of machine room,and integrates the control of other auxiliary equipment such as refrigeration main engine,water pump and cooling tower by introducing the third-party control system,so as to achieve the purpose of overall management and energy saving.In the new control system,the water pump and the cooling tower fan are all controlled by variable frequency energy saving,and the relevant parameters are collected and calculated by PLC control program.Finally,the output instruction is sent to the equipment layer for execution,and the strategy of energy saving group control in the machine room is finally realized.In this paper,the energy-saving group control system of refrigeration room is designed and analyzed.The main work and research results are as follows:First,based on the investigation and research on the common air conditioning system in the market,the current situation of the mainstream air conditioning system in the market is analyzed.Combined with the natural advantages of my own specialty,the group control of energy conservation is studied and a more energy saving,more stable and more intelligent group control strategy is explored.Second,involved in the group control system equipment,such as host,frozen pump,cooling pump,cooling tower fan equipment such as the circuit design,in the frozen water pump,cooling water pump,cooling tower fan front with frequency converter,with the method of variable flow water pump frequency conversion and control strategy of combining water chillers,cooling tower.Completed the frozen water pump,cooling water pump,cooling tower fan is part of the electrical wiring diagram and PLC control program,and at the completion of the frozen water pump,cooling water pump,cooling tower fan after modification,increased the host linkage program with cold water,namely by tracking the cold water host load fluctuation real-time adjustment of frozen water pump,cooling water pump,cooling tower fan operation,satisfied under different load,water pump and fan operation requirements.Third,on the frozen water pump,cooling water pump,cooling tower fan host relationship with cold water after the improvement,build room BIM model,through computer room BIM model can clearly analysis the status of the engine,find a host in cold water,frozen water pump,the position of the cooling water pumps and cooling tower fan,and pipe,and according to the characteristics of room to develop relevant control strategies,including water temperature,water pressure sensor installation quantity and installation location,the number of water valve and installation etc.,and establishment of control model,run from hundreds or thousands of combinations,Find out the working state point which can satisfy this cooling load and the lowest total energy consumption of the whole air conditioning system.