Research Of Fault Current Limiter Based On Fast Switch

With the rapid development of economy,the continuous expending of industrial production and the improving of power grid level,when a short-circuit fault occurs,the shortcircuit level continues to increase.Excessive short-circuit current will cause serious damage to power equipment,affects power quality,and increases the difficulty of high-voltage equipment selection.Fault current limiter(FCL)can effectively limit the short-circuit current within a safe range,so its research is of vital importance.On the basis of summarizing the research of fault current limiter at home and abroad,this paper proposes a new fault current limiter based on fast switch.It has the advantages of small volume,low cost and fast operation speed,and can be easily installed at any position of the line to quickly and effectively limit the fault current.Firstly,the paper introduces the principle and topology of the fast switch fault current limiter,and introduces the opening and closing principle of the electromagnetic repulsion hybrid operating mechanism.We build the 10 k V distribution network model,and simulate the current limiting effect of four common short-circuit faults.The simulation results show that the new FCL can effectively limit the short-circuit current and restrain the voltage sag.We also build the arc model of circuit breaker breaking process,and simulate the influence of arc model parameters on the current transfer process.The results show that the dissipated power P is the most sensitive element to the current transfer process.Secondly,a fast short-circuit fault identification algorithm based on improved least square algorithm(RLS)and current instantaneous value is proposed,and the judgment threshold required by the algorithm is simulated and analyzed by MATLAB software.The hybrid algorithm takes both rapidity and accuracy into account,and can quickly identify the short circuit fault within 2-3ms after the fault occurs.Then,this paper introduces the overall structure of the fast switch,and designs the hardware circuit of the current limiter controller,which is mainly divided into CPU module,power module,acquisition module,control module,storage and communication module,etc.According to the requirements of hardware circuit,the software control program is programmed,including current sampling conditioning subroutine,short circuit fault judgment subroutine,switching control subroutine,communication program,etc.Finally,the design and manufacture of 10 k V fast switch FCL prototype are completed,the main components of the prototype are introduced,and the opening and closing experiments are carried out.The experimental results show that the opening time of the prototype is less than5 ms,the average opening speed is 2.2 m/s,the closing time is less than 8ms,and there is no obvious closing bounce,which proves the rapidity and stability of the prototype.The experimental platform is built to verify the algorithm.The results show that the algorithm can quickly predict the short-circuit fault at any time.The fast switching current limiter designed in this paper can quickly complete the current limiting action when the short circuit fault occurs,protect the safe and reliable operation of the power system,improve the power quality,and has a good application prospect in the power system and industrial field.