Study On Wide-Area Backup Protection Based On Fault Component And Random Matrix Spectrum Analysis

With the expansion of the scale of power system,the structure of power system become more and more complex.The conventional backup protection has many disadvantage such as complicated setting,complex time series,high time delay and so on.These reasons make it difficult to find faulted branch during the complex condition.The setting of wide-area backup protection is simpler than conventional backup protection and there is no complicated timing coordination among the various protections.It can use wide-area information to determine the fault area and remove the fault elements quickly when main protection fail to act.Because of existing wide area backup protection algorithms have poor performance in high-resistance failure and power swing,Fault element identification algorithm is main researched in this paper.Firstly,three structures of the wide-area backup protection system are introduced in this paper from the aspects of communication mode,equipment investment and so on.The advantages and disadvantages of the three structures are giving in the paper.And then the existing fault region search method and its principle are summarized.In this paper,a fault line detection algorithm based on fault component is proposed.The ratio that consists of the vector sum and vector difference of both side currents fault component is used as the line fault judgment.The difference of the judgment between fault and normal line is analyzed and the criterion is constructed.When power swing occur,the location of the fault point which is calculated by the fault components of voltage and current is used as an auxiliary criterion to identify the fault line.That the transition resistance has no influence on the fault judgment is proved through the formula derivation and the distribution of fault judgment is quantitatively analyzed in theory,which is just related to the line impedance,the equivalent impedance on both ends and the fault location.The simulation experiments on IEEE-39 testing system verify proposed algorithm that can accurately detect the faulted line under various faults scenarios and it is not affected by the fault location,transition resistance,open-phase operation and flow transfer.A wide-area backup protection algorithm based on random matrix spectrum analysis is proposed in this paper.Firstly,we sort out the suspicious fault related bus by comparing the three sequence voltage of bus.The waveform sequences of the both ends current fault components are duplicated,translated and noise is added in them.After these work,the original random matrix is generated.According to the random matrix theory,the matrix of the original random matrix is transformed to get the fault recognition matrix and calculate its eigenvalues.Probability distribution of eigenvector is counted and the eigenvector whose probability is lower than 5% will be deleted.We calculate the average spectral radius after deleting the eigenvector and the average spectral radius is used as fault judgement.Branch will be judged as fault when its average spectral radius is lower than the threshold.The test results of the IEEE39 bus system verify that the proposed algorithm is not affected by the location of the fault point,the fault type,the mode of system operation,the power flow transfer and the power swing.The fault line can also be identified correctly when high-resistance faults occur and the simulation test of impulse noise proves that the algorithm is almost unaffected by false data.