A line fault identification method based on the principal component cluster analysis using the pole line fault voltage curve cluster
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A fault voltage and line fault technology, applied in the fault location and other directions, can solve problems such as DC blocking accidents, poor robustness of protection algorithms, poor ability to withstand transition resistance, etc., and achieve the effect of effective description
Active Publication Date: 2018-04-24
KUNMING UNIV OF SCI & TECH
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Problems solved by technology
Among them, traveling wave protection and differential undervoltage protection are the main protections, and the action protection speed is fast, but they are easily affected by interference such as harmonics, lightning strikes, and sampling value jitter, and the ability to withstand transition resistance is relatively poor
The reason why it is susceptible to interference such as harmonics, lightning strikes, and sampling value jitter is because the robustness of the protection algorithm is poor; the traveling wave protection with the voltage change rate du / dt as the core criterion often cannot detect the remote high-impedance fault of the UHVDC line , the fundamental reason is that with the increase of transition resistance and fault distance, du / dt decreases, and it is impossible to effectively distinguish the internal high-impedance grounding fault and the external fault of the line within the stretching time
The longitudinal differential protection and low-voltage protection are used as backup protection, and the action time is longer [4-8]
As a high-impedance fault detection, the longitudinal differential protection relies on time delay to avoid the transient response during the AC system fault to ensure that it does not malfunction. At the same time, in order to avoid malfunction during power adjustment, SIMENS differential protection design The blocking logic is added, so the exit delay of the longitudinal differential protection is too long. On the one hand, the longitudinal differential protection may often fail to function as a backup protection. On the other hand, the protection of the DC control system may act first. Cause unnecessary DC blocking accidents
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Embodiment 1
[0021] Embodiment 1: adopt figure 1 In the simulation system shown, according to the above steps (1) and (2), the clustering results of line faults and external faults in PCA space are obtained as follows: image 3 shown. Select 4 cluster centers as the cluster centers of line faults, namely (-1.7261,-0.3977), (-1.2570,-0.2770), (-0.9649,-0.2062), (-0.8875,-0.1960) and 1 external Fault cluster centers (-0.2556, -0.2761). And express the Euclidean distance between the test sample data and the four centers of line fault clustering as d 1 ~ d 4 , the Euclidean distance table between the test sample data and one center of the external fault cluster is d 5 .
[0022] (1) Calculate d according to steps (3) and (4) in the claims 1＝ 0.0345, d 2＝ 0.5063, d 3＝ 0.8064, d 4＝ 0.8837 and d 5＝ 1.4921;
[0023] (2) get d according to step (5) in the claims min = d 1 , so it is judged as a line failure.
Embodiment 2
[0024] Example 2: The fault distance is 400km from the M terminal, and the transition resistance is 100Ω.
[0025] (1) Calculate d according to steps (3) to (4) in the claims 1＝ 0.8024, d 2＝ 0.3182, d 3＝ 0.0199, d 4＝ 0.0602 and d 5＝ 0.6931;
[0026] (2) get d according to step (5) in the claims min = d 3 , so it is judged as a line failure.
Embodiment 3
[0027] Example 3: The outlet of the rectifier side is faulty, and the transition resistance is 10Ω.
[0028] (1) Calculate d according to steps (3) to (4) in the claims 1＝ 1.4920,d 2＝ 1.0082,d 3＝ 0.7082, d 4＝ 0.6302 and d 5＝ 0.1888;
[0029] (2) get d according to step (5) in the claims min = d 5 , so it is judged as an out-of-area fault.
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Abstract
The invention relates to a line fault identification method for performing principal component cluster analysis by utilizing pole line fault voltage curve clusters, and belongs to the technical field of electric power system relay protection. Set single-pole ground faults along the line from near to far; set rectifier side outlet faults, rectifier side AC system faults, inverter side outlet faults and inverter side AC system faults for external faults. Under the sampling rate of 10kHz, the extreme line voltage curve clusters under faults within the entire length of the line and the external faults of the line are respectively obtained by simulation, and the data within 1 ms of the extreme line voltage curve clusters are selected for PCA cluster analysis, and two principal components are taken The 2-dimensional PCA space formed by PC1 and PC2. In this way, two types of cluster point clusters reflecting line faults and external faults are formed on this PCA space. When a fault occurs, the polar line fault voltage data in the 1ms time window of the test data is mapped to the 2-dimensional PCA space, and the Euclidean distance is used to measure the distance between the test data and the two types of point clusters, and constitute the fault identification criterion.
Description
technical field [0001] The invention relates to a line fault identification method for performing principal component cluster analysis by utilizing pole line fault voltage curve clusters, and belongs to the technical field of electric power system relay protection. Background technique [0002] At present, the DC transmission line protection that has been put into operation in my country is mainly based on the so-called traveling wave protection, differential undervoltage protection, longitudinal differential protection and low voltage protection based on the change rate and change amount. Among them, traveling wave protection and differential undervoltage protection are the main protections, and the action protection speed is fast, but they are easily affected by interference such as harmonics, lightning strikes, and sampling value jitter, and their ability to withstand transition resistance is relatively poor. The reason why it is susceptible to interference such as harmon...
Claims
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