Research On Wide Area Backup Protection Algorithm Based On Fault Fit

With the continuous expansion of the scale of the power grid,the topology of the power grid becomes more complex and the operation mode becomes more flexible.The disadvantages of traditional backup protection gradually emerged,mainly reflected in the traditional backup protection setting calculation and mutual cooperation become more difficult,the traditional backup protection operation time is longer,and prone to misoperation,may cut out the normal line to expand the scope of power failure and a series of problems.Due to the limitation of traditional backup protection,the research and application of wide-area backup protection algorithm is urgently needed at present.To solve the above problems,this paper proposes a wide-area backup protection algorithm based on fault fit.In the case of power grid fault operation,the expected function of protection action is constructed by the weight value of current protection action and the actual action state of protection device.The fitness function of protection action is constructed by weight value of current protection,probability of fault position and theoretical action state of protection device under normal operation of power grid.The fit of directional current protection was obtained by dividing the expected function of protection action by the fitness function of protection action.Finally,the fault line was judged by the fit value.In order to verify the feasibility of the proposed wide area backup protection algorithm,the two-terminal power supply system is taken as the research object in PSCAD.First,simulation experiments are carried out in the case of a single line fault to verify the feasibility of the proposed algorithm.In view of the problems existing in the identification of double faults by the algorithm in this paper,the fault fit threshold is constructed to screen out suspected fault lines.Then,according to the characteristic that the maximum fault voltage ratio when a fault occurs in the line is different from the maximum fault voltage ratio when a fault occurs outside the line,we determine whether the suspected fault line is the actual fault line.Finally,in the case of double faults,simulation experiments are carried out to verify the feasibility of the proposed method in identifying double faults.In order to further comprehensively study the wide-area backup protection algorithm proposed in this paper,the IEEE-14 node active distribution network is taken as the research object in PSCAD.First,different types of short circuit faults are set at different positions of the line.The simulation results show that when different types of short circuit faults occur at different positions of the line,The wide area backup protection algorithm proposed in this paper can judge the fault line correctly.Then,it is analyzed that in the case of random N-bit protection information error,the faulttolerant information bits of the wide area backup protection algorithm in this paper can reach 4 bits.Furthermore,the wide area backup protection algorithm proposed in this paper is compared with the wide area backup protection algorithm based on correlation matrix in the fault tolerance number of protection information under the same conditions,highlighting that the wide area backup protection algorithm in this paper has a stronger ability to identify fault lines.Then,when two phase ground short circuit fault occurs on the line,different transition resistance values are set to study the accuracy of the proposed wide area backup protection algorithm in identifying the fault line.The research shows that the proposed wide area backup protection algorithm has a certain ability to resist the transition resistance.Finally,when different types of double faults are set in IEEE-14 node active distribution network,the proposed wide area backup protection algorithm can identify the double faults correctly and reliably.Figure [31] table [65] reference [82]...