The FI820F 3BDH000031R1 multi-loop temperature control system should mainly have four basic functions, namely, real-time control function, display function, data processing function, alarm and fault handling function [4]. According to the main functions of the above system, the overall structure of this multiplexed temperature control system is designed, and the schematic diagram of the overall system structure is shown in Figure 3. The hardware of the whole temperature measurement and control system includes data acquisition module, output control module, RTD, solid state relay, human-machine interface and total controller.

FI820F 3BDH000031R1 Among the heating methods such as induction heating, infrared heating and resistance heating, for blade mould heating, resistance wire heating has the advantages of durable components, easy maintenance and replacement, simple operation and low cost. Resistance wire heating is the pre-buried heating resistance wire in the FRP layer of the mould, and the heating resistance wire is laid under the heating layer (resin + aluminium powder) of the mould [3]. Although the resistance wire heating method is more commonly used, with the growth of wind turbine capacity, the size of wind turbine blades increases, and the heating system of megawatt-class large wind turbine blade moulds is characterised by many and complicated division areas, the

FI820F 3BDH000031R1 based on the resistance wire heating mode of the mould heating system appears to lack of reliability, the temperature is not easy to control, prone to the phenomenon of local temperature is too high, so for the blade molding mould temperature control system puts forward a higher process requirements. As a cpu unit, the module type plc has high reliability, strong anti-interference ability, and is suitable for multi-channel temperature control. cj1g series plc has a temperature control unit that supports 2-loop or 4-loop pid control or on/off control, of which the 2-loop mode has a heating circuit break detection function; at the same time, the pid constants used in the pid control can be set by self-adjustment (at).