An estimation-based fault detection method for transmission lines under limited pmu

Abstract

The invention discloses an estimation-based transmission line fault detection method under limited PMUs. The strategy of arranging PMUs at intervals is adopted to divide the power grid into several areas, and the total estimated current of unarranged PMU buses is estimated, and detected according to whether it exceeds the threshold. In the suspected fault area, the t-test is used to check and correct the data out of synchronization in the suspected fault area; using the data of each PMU, the positive sequence estimated voltage and estimated current of the undistributed PMU bus are estimated more accurately, and the double-terminal ranging principle is used. The fault distance of each suspected line is calculated separately, and the fault detection criterion of transmission line under limited PMU is established. The invention can correctly detect the fault line without being affected by the fault position, fault type and transition resistance, and still has high detection accuracy for a certain error of the line parameters, and has a certain anti-out-of-synchronization ability.

Description

Technical field[0001]The present invention belongs to the field of power system fault detection, and in particular to a limited PMU based on estimated transmission line fault detection method.Background technique[0002]With the development of the electricity system, the grid structure is increasing, and the traditional protection setting based on local signals has become difficult [1-3]. Due to the advantages of the Phasor Measurement Unit, PMUs have the advantages of high time accuracy and accurate measurement results, the PMU is introduced to the failure detection and positioning of the power transmission line to provide new means [4, 5]. Considering the economics of the PMU layout, there is a need to study the transmission line fault detection method for limited PMU layout.[0003]Document [6] detects the fault line by comparing the absolute value of the positive sequence current phase angle of the suspected fault line; the literature [7] uses the least squares method to estimate th...

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Problems solved by technology

[0003] Literature [6] detects the fault line by comparing the absolute value of the positive sequence current phase angle at both ends of the suspected fault line; Literature [7] uses the least square method to estimate the voltage of each node, then estimate the current of each line, and calculate the current residual to Judging the fault, but the estimated voltage is not accurate enough; literature [8] uses fault correlation factors to identify suspected fault lines; literature [9] proposes a line protection principle based on differential active power, which has a strong ability to resist transition resistance; literature [10] proposes Backup protection scheme based on voltage fault components and power distribution, but requires PMUs for all busbar arrangements

[0004] Literature [11][12] uses the distributed parameter model under the finite PMU strategy to calculate the voltage and current of the fault point, and establishes the equation from the perspective of pure resistance of the fault path to accurately obtain the fault location, but the calculation process is more complicated; Literature [13 ]Using the fault components of the finite PMU and combining two pure fault equivalent models to accurately locate the fault point, but it is based on the lumped parameter model, which may not be suitable for actual long lines

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