【 Weak current College 】 converters'applications application of energy-Power By 【 China power house network 】

First, the necessity of the pump energy saving
Central air-conditioning is the power consumption in the building, large annual electricity consumption of air conditioning in occupies 60%, therefore the central air conditioning energy saving is very important.
Due to the design-time, central air conditioning system must be weather, load maximum design and remain 10-20% design margin, but in fact most of the time air conditioning is not running in the full load condition, there is a large surplus, so energy-saving potential is larger, which, according to the frozen host can load changes with loading or unloading, frozen water pump and cooling water pumps cannot load changes accordingly adjusted, a lot of waste.
Water pumps systems of flow and pressure on the valve and by-pass regulation, therefore, inevitably exist large dams and large flow and high pressure, low temperature difference, not only a lot of wasted energy, but also have central air-conditioning end up to a reasonable result. In order to solve these problems need to pump as load changes in the regulation of water flow and close by-pass.
Then due to the water pump is Y-△ start mode, motor starting current for the rated current for 3 to 4 times, one of the motors of its 90KW starting current will reach 500A, in such a storm, contactors, motor service life significantly decreased, while at the same time, start-up of mechanical shock and when water pumping, easy hanging on mechanical parts, bearings, valves, piping and other damage, thereby increasing maintenance workload and the cost of spare parts.
Heald, in order to save energy and money, need to be transformed to pump system, market research and understanding of mature converter to achieve in order to achieve energy-saving and extended motor, contactor and machinery parts, bearings, valves, pipe life.
This is because the converter according to the frozen water pump and cooling water pump load changes with adjustment pump motor speed,to meet the central air conditioning system functioning in the frozen water pump and cooling water pumps make corresponding adjustments to achieve energy-saving purposes. Water pump motor speed drops, motor power from the power absorption will be considerably reduced.
Its reduced power consumption △ P = P0] [1-(N1/N0) 3-2600 (1)
Reduction of flow △ Q = Q0] [1-(N1/N0)-Gordon (2)
Where N1 is a change of speed, N0 for motor original speed, P0 is the original motor speed of motor power, Q0 to original motor speed flow generated by the pump.
As can be seen from the top-flow-reducing and speed reduction of time proportional to the square, but power consumption reduction, and speed reduction in direct proportion to the third party.
Example: suppose the original flow of 100 units of energy to 100 units, if the speed reduction to 10 unit (2)-△ Q = Q0] [1-(N1/N0) s = 100 *] [1-(90/100) s = 10 to get traffic changed 10 units, but power consumption by (1)-△ P = P0 [1-(N1/N0) 3] = 100 *] [1-(90/100) 3 s = 27.1 can conclude that the power will reduce 27.1 units, namely 27.1% than the original.
Then for inverter is soft start mode, after adopting Inverter control motor, motor start-up and operation of the process shall not impact current and surge current is a contactor, motor service life is the most important, most direct factors, while adopting inverter controlled motor also avoids water down phenomenon, it can greatly extend the motor, contactor and machinery parts, bearings, valves, pipe life.
　　
Second, the pump energy saving programmes
Central air conditioning system is usually divided into frozen (media) water and cooling water systems (below, left half-frozen (media) water system, the right half is the cooling water system). According to the latest information at home and abroad, and more through the central air conditioner pump system for closed-loop control of success stories, now pump system energy saving programmes mostly adopts frequency converter.
1, frozen (medium)-pump system with closed-loop control
«1 2600, refrigeration mode chilled water pumps systems with closed-loop control
The programme, while guaranteeing the supply of frozen water of terminal equipment, determined that a frozen pump inverter work of minimum operating frequency, the frequency of its set to lower and lock, frequency modulation frequency of the chilled water pumps are installed in the backwater of frozen water system is in charge of the temperature sensor detection on freezing water return water temperature through the temperature controller setting to control how often changes, Inverter control by freezing water temperature is greater than the set temperature-time frequency electrodeless upward.
«2 answers, the heating mode of frozen water pumps systems with closed-loop control
This mode is in the central air conditioning and heat pump operation (heating) chilled water pumps systems of control programmes. With refrigeration mode control programmes, in ensuring the supply of frozen water of terminal equipment, determined that a frozen pump inverter work of minimum operating frequency, the frequency of its set to lower and lock, frequency modulation frequency of the chilled water pumps are installed in the backwater of frozen water system is in charge of the temperature sensor detection on freezing water return water temperature through the temperature controller setting to control the frequency of the inverter. The difference is: frozen water temperature is less than the set temperature-time frequency electrodeless upward, when the temperature sensor detects that the higher the temperature of freezing water, the inverter output frequency.
Shanghai, Toyokawa design of air conditioning Inverter control system with the above features by installing in chilled water system water temperature sensor on the charge to test the return water temperature of the chilled water, and can be directly by setting the converterparameter enables the system temperature regulation in the context of the need.
In addition, in response to past reconstruction programme in the first run-time temperature exchange of defect, Shanghai, Toyokawa design of Inverter control system increased first-time start-up full-operation function, by setting the converter parameter allows full exchange of frozen water system for a period of time, And then under chilled water temperature on frequency stepless speed regulation, and the inverter output frequency is tested and the backwater temperature signal via temperature setpoint PID calculation.
2. cooling water system of closed-loop control
At present, in the cooling water system improvement programmes are most common, power-saving effect is more pronounced. The programme also ensures cooling tower has some cooling water flow out, by controlling the inverter output frequency to adjust the cooling water flow, central air conditioning cooling water outlet temperature is low, reduce the cooling water flow; the central air conditioning cooling water outlet temperature is high, and increase the cooling water flow, so as to achieve the promise of central air conditioning unit works on the premise that the purpose of achieving energy efficiency.
The existing control methods are mostly first determine a cooling pump inverter work of minimum operating frequency, it is set to
Lower frequency and locked, the frequency inverter is cooling water pump for water cooling pipe inlet and outlet temperature difference and to adjust the temperature signal, when the water temperature is greater than, the set value, frequency electrodeless discharge rates, when the water temperature is less than, the set value, frequency electrodeless downward, at the same time when the cooling water outlet temperature is higher than the set value, frequency, priority-polar cooling water outlet temperature is lower than the set value, press difference in temperature changes to adjust the frequency, the greater the temperature difference between inlet and outlet, the higher the frequency inverter's output; into smaller temperature difference, the water, the inverter output frequency.
Shanghai, Toyokawa by market investigation and understanding, and application and demonstration of multiple practice are used for cooling water closed-loop control of series uses the same refrigeration mode chilled water pumps systems closed-loop control as control.
And other manufacturers of control than the benefits are:
1, just in central air conditioning cooling pipe in the water-side installation of a temperature sensor (such as diagrams, installed in the cooling water system in the central air conditioning cooling water effluent charge on B), simple and reliable.
2, when the cooling water outlet temperature is higher than the temperature upper limit setting value, the frequency of direct priority to limit frequency.
3. when the cooling water outlet temperature is below the lower limit of temperature settings, the frequency directly downward to the lower frequency priority. A cooling pipe inlet and outlet temperature difference to regulate difficult to reach this point.
4. when the cooling water outlet temperature is between temperature limits set value and temperature upper limit setting values through the temperature of the cooling water effluent and temperature upper/lower limit setting for PID calculation, so as to achieve the frequency stepless speed regulation, closed-loop control to quickly and accurately.
5. energy-saving effect is more pronounced. When cooling water outlet temperature is lower than the temperature upper limit setting value, the use of cooling pipe inlet and outlet temperature difference to Regulation No water temperature low energy saving this factor into account, but only by the temperature difference to frequency stepless speed regulation, but uses the upper and lower temperature adjustment mode to take full account of this factor, therefore energy-saving effect is even more apparent, through a number of user market survey, the average electricity-saving rate to 5 per cent of the electricity-saving rate is 20%-40%.
6, starting with the first run at full speed. By setting the converter parameter value allows full exchange of water system for a period of time, avoid just starting runtime heat caused by insufficient system water flow is too small.