Controlled Object Analysis According to the requirements of the national standard, the abnormal operation test of the air conditioner compressor requires continuous overload and final trip test after the system enters a stable state. Steady state means that the evaporation temperature, condensation temperature, suction temperature and temperature of the compressor's environmental chamber are kept within the specified range, which is the control task of the test system. Since the first two are difficult to measure, and the suction pressure and the exhaust pressure correspond to each other, the actual controlled performance parameters are taken as the intake temperature, the suction pressure, the exhaust pressure, and the compressor ambient temperature, which are respectively adjusted by the side. The valve opening degree, the throttle opening degree, the exhaust pressure regulating valve opening degree and the environmental chamber electric heater power are controlled. Its dynamic mathematical model is shown. Medium W11 (S), W22 (S), W33 (S), and W44 (S) indicate the intake air temperature, the suction pressure, the exhaust pressure, the compressor ambient temperature, the bypass valve opening degree, and the throttle opening degree, respectively. The transfer function of the valve opening of the exhaust pressure regulating valve and the electric heater power change of the environmental chamber; the transfer functions W21(S), W23(S) and W32(S) of the cross-connection in the figure indicate the mutual coupling between the respective variables. . The performance parameter control is known by the control model. All external disturbance inputs can be considered constant after the equipment is running stably and the test conditions are established, and the external influence in the actual control can be neglected compared with the effect of the control channel. From the analysis of the controlled object, if the influence of the external disturbance is neglected, the control of the performance parameter can be handled as a single-input single-output control loop. The block diagram of the system adjustment is as shown. The relationship between the digital PID regulator input e(t) and the output u(t) is u(t)=Kpe(t)+1Tit0e(t)dt+Tdde(t)dt(1) where Kp It is a proportional coefficient; Ti and Td are integral time constants and differential time constants; t is time. After selecting the appropriate sampling period T, discretize the input-output relationship. Let u(t)=u(kT)(k=0,1,2,3,)e(t)=e(kT)t0e (t) dt=Tkj=0e(jT)de(t)dt=e(kT)-e(kT-T)T(2) gives the first expression of the digital PID regulator, called positional u(kT)=Kpe(kT)+Tikj=0e(jT)+TdT The system detection consists of FP101 of pressure transmitter YOKOGAWA, temperature sensor PT100, UT350 of control instrument YOKOGAWA and actuator regulating valve M2FP. The control of the electrical system control electrical system adopts a programmable logic controller (PLC) with convenient operation, strong anti-interference ability and high reliability, which replaces the traditional relay control mode. The electrical control circuit includes a main circuit and a control circuit. For safety, protective devices such as circuit breakers are added to these high-power lines, and three-phase motor protectors are added to the three-phase circuits to prevent accidents caused by overload and phase loss, damage to electrical equipment or endanger personal safety. The PLC control function is to start and stop the load of the compressor and the interlock protection of these loads to prevent the compressor inlet pressure from being too low and the outlet pressure to be too high. The operation of the test bench adopts the operation mode of the touch screen, which replaces the traditional button control and has an alarm window on the touch screen. When a certain device has an alarm, it emits an audible and visual alarm signal, and automatically cuts off the power of the alarm device until the alarm is eliminated. You can then restart the device. Non-normal operation test and analysis test requirements of the compressor The YOKOGAWAUT350 regulator used in this test bench has a parameter self-tuning function, which can automatically optimize the setting parameters according to the operating conditions, but the parameters automatically set by the regulator in actual applications are not Satisfactory, so the adjustment parameters must be adjusted according to the control curve. After the initial commissioning, a continuous overload test can be performed. Test conditions: ambient temperature of 43, evaporation temperature of 12, condensation temperature of 65, and suction temperature of 25. Air conditioning parameters tested: Model is SL242SV, power supply is single phase / 220V / 50Hz, working medium is R22. The continuous overload test connects the compressor to the refrigeration circuit, with the maximum rated voltage of 1.06 times (233.2V) as the power supply voltage U, and operates under test conditions until steady state, and then 0.94 times the minimum rated voltage ( 206.8V) Repeat this test for the supply voltage, the test results are shown. The system has reached a stable working time of less than 10 minutes, and the working condition has good stability and high control precision. From the control curve of the performance parameters, it can be seen that after the working condition is stable, the fluctuation of the suction temperature is within 0.2%, the fluctuation of the ambient temperature of the compressor is within %0.3, the fluctuation of the suction pressure is within %2kPa, and the exhaust pressure The fluctuations of the parameters are within 3 kPa, and the control accuracy of these parameters is far superior to the control requirements stipulated by the national standards. Smms Spunmelt Nonwoven Production Line
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Development of an unconventional operation test bench for air compressors based on gasification loopback method
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