Short Circuit Current Limiting Measures And Optimal Configuration Of Power Grid Based On Fast Switch Fault Current Limiter

With the increasing expansion of power grid scale and the continuous access of new energy,the level of short-circuit current of the system is increasing year by year,which has become one of the main problems in the safe and stable operation of the current power grid.Traditional current-limiting measures such as split buses and hierarchical partitions have obvious current-limiting effects,but the construction period is long,the investment is large,and it is difficult to guarantee the reliability and network integrity of the power grid operation.The current limiting reactor is economical and simple,but it will increase the network loss and reduce the system stability.Fast switching fault current limiter is a new type of fault current limiter proposed in recent years.When the loss is close to zero in normal operation,the input current limiting reactance can be quickly disconnected in case of failure,making the fault current lower than the blocking capacity of the circuit breaker.The type of FCL has a smaller investment under the same current limiting effect.Based on the comparative analysis of the advantages and disadvantages of various types of FCL,this paper introduces the structural principle,characteristics and shape structure of FSFCL.The current-limiting effect of FSFCL and the theory of transient stability characteristics are studied.The current-limiting effect of FSFCL is verified by using MATLAB / Simulink simulation software and field tests.The transient stability of the system after FSFCL string is verified by PSASP software.In the power grid,if there are many short-circuit current out of scale points which are widely distributed in different regions,the difficulty of fault current limiting research is the number,impedance and distribution of FSFCL.Considering the global current limiting effect of the power grid and the optimal configuration of FSFCL capacity,an FSFCL global optimal configuration model based on the improved PSO-GSA algorithm is proposed.The sensitivity method based on the branch impedance is used to reduce the search space.The current limiting effect and the cost of the current limiter are taken as the optimization objectives,and the fitness function is constructed.Using particle swarm optimization to improve the gravitational search algorithm(PSO-GSA)and further improve the hybrid algorithm,the optimization process of the algorithm is formulated.The effectiveness of the global optimization configuration model was verified by IEEE39-node system simulation.At the same time,the current limit of the limiter may not reach the global optimal effect when judging the current limit scheme based on manual experience.Through the establishment of the evaluation model of the scheme,the combined weight of each index was determined according to the principle of relative entropy,and then the weighted approach to the ideal point sorting method was used to sort the scheme and select the optimal configuration scheme.The scheme evaluation model in this paper can avoid the blindness of installing FSFCL line only by manual experience and effectively reduce the cost of power grid planning.