Fuzzy control is to make all kinds of sensors to convert the precise amount of suitable for fuzzy arithmetic of fuzzy quantity, then computing the amount in the fuzzy controller, finally, the computing results of the fuzzy quantity is converted to a accurate quantity, so that each actuator for specific operation control, the roots blower fuzzy control principle of this system is shown in figure 1, yT fan outlet pressure given, y fan outlet pressure.
FIG. 1 schematic diagram of fuzzy control
The characteristic of roots blower is that the rotation speed of the blower is directly proportional to the gas flow at the outlet of the blower. When the rotation speed of the blower is certain and the inlet pressure fluctuates slightly, the gas flow at the outlet of the blower remains unchanged.
In this system, roots fan adopts pressure frequency conversion speed regulation.The actual pressure at the outlet of the fan is compared with the given pressure, and the regulating signal is obtained by the fuzzy controller. The frequency converter changes the motor speed according to the signal and then changes the fan speed, finally achieving the purpose of regulating the flow rate at the outlet of the fan and saving energy.The system block diagram of fan control is shown in figure 6.
FIG. 2 block diagram of fuzzy control system for roots fan pressure
PLC can monitor the gas pressure and flow rate in the gas main pipe through the control of roots fan according to the data detected by the field instrument, so as to meet the requirements of the next biogas generator set.Using PLC as the control system not only saves a lot of manpower and material resources, but also ensures the reliability of the system operation [3].The field situation shows that the system runs stably and the control effect is ideal. The automation level of landfill gas power generation project and the precision of system monitoring and control are proposed.
conclusion
Landfill gas power generation is an important means to realize waste reduction, recycling and harmless treatment.Engineering practice has proved that the landfill gas power generation in the rational use of automatic control system, greatly has made to the process system and equipment monitoring, control and management, improve the production efficiency, reduce the accident rate, improved the production conditions, greatly reduces the instrument, the equipment maintenance cost, simple structure, reliable operation, easy to implement.
