Weak current College】 【ice storage air conditioning system basic functions --- Power By】 【China power house network.

<br> Ice storage air conditioning due to their characteristics and the control system has a dependency, and it determines the basic functionality of automatic control system. Generally speaking, ice storage air conditioning on the automation system has the following four basic requirements: <br .> <br> 1. operating mode switch and the start-stop control device. Ice storage air conditioning is on the same pipe system through the pumps and valves, and other devices with different combinations and different conditions and different condition combinations also reflect the different .operational policy. Therefore, select ice storage air conditioning is to reduce the cost of running on the device and provides a possible, but really needs to reduce the cost of running all of the devices in the system to combine, and enable the operator to quickly .and easily switch between the various operating conditions. <br> <br> On specific projects, the different conditions on participation in the operation of pumps and valves open and close all have different requirements, at the same time, the device boot order and devices .start interval has specific requirements. This requires the automatic control system for operating switch provides convenient, secure means of action. Ideally, the operator wished to pass the mouse on the screen, click on or through the menu selection you can switch condition. However, .the automatic control system provides the ease of operation and to be able to prevent personnel misoperation, it is recommended that the operating mode switch, and system startup is a two-step operation, ie the switch condition is only for system start up conditions of choice ., rather than directly after the switching condition of the system boots. <br> <br> 2. melt rate control. In order to truly move peak, ice storage system is the pursuit of higher melting rate, with a view to be in peak .power hours completely free cooling capacity. But the resulting problem is that if you do not melt rate control the ice plant will be the fastest speed of melting, the amount of waste caused by cold. Therefore, ice storage air conditioning system can request-rate .control, so that it can track the load condition and meet system on cooling capacity requirements. <br> <br> Control-rate methods vary, but generally can be grouped into two categories: changes in water temperature and changes in water flow. If .the heat exchanger for ice unit load to describe that changed is the heat exchanger chilled water temperature of the side into the water, which changes the heat exchanger chilled water side into the water flow. Typically, a way to better take into account heat transfer efficiency ., pursuit of lower heat temperature difference. <br> <br> Control-rate of the ultimate goal is to control the temperature of the water. Because the pipeline in the great inertia, once established the trend toward natural after a temperature change and does .not immediately on control system of regulation to respond, this makes the circuit of control properties to be soft, and there was a lot of lag. Piping water temperature of these characteristics make regular PID often do not produce the desired effect. Therefore, in a .more sophisticated application in the control model to measure the darker feedback, conditions permitting, you can control model introduced in certain warning measures so that the controllers of the actions before the temperature changes arise. <br> <br> 3, air conditioning, water .supply and return water differential pressure control. When a terminal with variable flow system, air conditioning water for water mains pressure difference between the end of use. Although variable flow Terminal system has many advantages, but if not for the difference between the return duct pressure .control, its harm is evident. First, the differential pressure fluctuations will make the entire pipeline system control valve valve power of change, this will undermine the general stability of the PID control loop, when the valve to reduce the degree to a certain extent also .causes the control valves. Second, when the pressure is low, will enable the distal end of the energy supply is insufficient, use effects; on the contrary, the differential is too large and will affect the security of Terminal system. Therefore, this requires .the control system can make to the differential pressure, real-time monitoring and to take appropriate means to enable the adjustment of the differential pressure stability within a reasonable range. <br> <br> Control air conditioning water for the difference between the return duct .pressure, simple and proven method is in the air conditioning water for water mains on retrofitting the bypass valve, control system under real pressure to adjust the valve to open degree. In the heat exchanger system, this approach can guarantee through a heat exchanger secondary side .flow constant values in the design, to take into account heat transfer efficiency and lower the temperature of the heat exchanger. The drawback of this method is the pump costs cannot be reduced with the load. At the same time, the bypass valve of the differential .pressure vary greatly, this results in large degree the right to change the valve, the bypass valve is often the actual work in the on / off status, cannot achieve the desired effect of the control. <br> <br> Therefore, another common .approach is to use the pump speed is adjustable. Air-conditioning automatic control system under the water for the difference between the return duct pressure to adjust variable speed pump speed, so as to achieve the aim of stabilizing differential pressure. In order to be in .the worst case still has enough water to ensure the safety of the water pump, many cases adopt speed pump after installation of the by-pass valve. <br> <br> 4. hourly load forecasting. Strict sense hourly load forecast is not a .control function, but because it on ice storage air conditioning system is important, therefore, included in the basic functions. <br> <br> To minimize expensive peak electricity use, operators need to be on the same day there is an hourly load, .thus develop operating strategies that seek to peak power hours rarely used cooler as far as possible, to make ice flux in peak power hours fully released. Lack of strict set action policies often yields this: or set aside too much cooling capacity resulting in a peak .at the end of the electric window still more the amount of remaining cold, or prematurely will chill completely free but have to peak electricity use cooler periods. Develop action policy significance could reasonable arrangements in ice volume of use, in addition to the peak electric period .to be set aside in the refrigerator because load lower operating efficiency decline use-melt cooling. <br> <br> Develop action policies based on hourly, so, hourly load forecasts on ice storage air conditioning lower operating costs is important. However, to .achieve the hourly load forecasts have considerable difficulty, this one is due to the impact factors of hourly load too much, mostly run on historical data requirements. .Current prediction method of hourly load of mostly historical data on the system running. <br> <br> <br> <br> <br>.