Research On The Operation Control And Safety Protection Strategy Of ITER HTS Current Leads

High temperature superconducting current leads can reduce investment in capacity expansion of cryogenic equipment and significantly improve economic benefits due to their excellent conductivity and cooling saving characteristics.They are indispensable components for superconducting magnet.The operating conditions of ITER hightemperature superconducting current leads are complex and their safety level is high.During a large number of cold temperature electrical experiments,it was found that the temperature control and adjustment time of the cold end of the heat exchanger is long and unstable,and repeated adjustments cause equipment wear and increased cold consumption.Improper dynamic control strategies during the operation phase pose significant safety risks,involving multi-party collaboration and having a significant impact on the reliability of current leads.Based on the above issues,this paper conducts research on the operation control and safe protection strategy of ITER current leads.The main contents include:(1)Conduct research on the dynamic control model for the heat exchanger cold end temperature control of high-temperature superconducting current lead.Analyzing the operational control requirements of high-temperature superconducting current leads,aiming at the high temperature control requirements of the heat exchanger cold end,study the heating model,and then obtain its dynamic model which is a first-order hysteresis model through mechanism derivation.Based on polynomial structure model and process structure model,study the system identification algorithm,obtain its polynomial first order,second order and process P1D,P2D models by system identification.(2)Design operation control scheme and simulation of control characteristics for high-temperature superconducting current leads.Design schemes for temperature control of room temperature copper head,cold end temperature control of heat exchanger,and low-temperature superconducting section temperature control.Based on the dynamic control model of the cold end temperature of the heat exchanger,study the temperature control characteristics of the cold end of the heat exchanger.Build a controller application simulation platform based on its model,conduct PID control simulation,and obtain PID control characteristic parameters;Design a fuzzy controller,apply the minimum stable time parameter as the initial condition,simulate and compare the characteristics of PID control and fuzzy adaptive PID control.(3)Conduct research on the safe operation strategy of high temperature superconducting current leads.Analyzing the design parameters,process characteristics,operating boundary conditions,operating conditions,and possible error scenarios of high-temperature superconducting current leads,combined with the experience of lowtemperature testing process and magnet discharge requirements,a controllable cooling and two-stage quench protection scheme is proposed,design chain protection strategies and build a secure operation protection platform.(4)Build the acquisition and control system for acceptance testing of HTS current leads.Based on the low-temperature performance testing requirements of the ITER series of current leads and the integrated operation interface with ITER equipment,the ITER CODAC distributed acquisition and control system architecture is adopted to build a distributed acquisition and control system.This control system integrates functions such as physical signal acquisition,display,control,storage,alarm,and interlocking protection.(5)Conduct experimental research on operational control and validation of security protection strategy.Conduct controllable cooling experiments,Standby zero current experiments,rated current steady-state operation experiments and LOFA experiments,cold end heat load experiments,joint resistance experiments,and pulse experiments based on the ITER PF current leads.Moreover,analyz process of the experimental results and verified analyz the results,whcih show that the operation control effect was good,and the safety protection met the experimental requirements.