Transformer excitation surge current identification method based on improved symbol sequence entropy method

Abstract

The invention discloses a transformer excitation surge current identification method based on an improved symbol sequence entropy method. The method comprises the steps: collecting the secondary current of current transformers at two differential protection sides of a transformer under a certain sampling frequency, forming a differential current signal sequence, judging whether the amplitude of the differential current sequence exceeds a setting value of a differential protection starting element or not, and if yes, starting a criterion to discriminate the fault differential current and the excitation surge current. The method performs normalization processing on a difference flow initial signal sequence to form a normalized difference flow signal sequence, compares the size change directions between two adjacent sampling points in a cyclic wave data window to form a new symbol sequence, and constructs a vector symbol sequence with the width of 2 by adopting a sliding window, only three modes of 00, 11 and 22 are reserved to calculate symbol entropies, the symbol entropies are compared with a set threshold value, if the symbol entropies are lower than the threshold value, an internal fault is judged, and a protection action is performed; and if the symbol entropies are higher than the threshold value, the excitation surge current or the non-internal fault is judged, and the protection is locked.

Description

technical field

[0001] The invention belongs to the technical field of transformer differential protection, in particular to a transformer excitation inrush current identification method based on an improved symbol sequence entropy method. Background technique

[0002] In recent years, the power industry has made great progress. With the continuous production of ultra-high voltage, ultra-high voltage and large-capacity power transformers in my country, more and more long-distance power transmission systems are built and operated, so the requirements for the safety, stability and reliability of power systems are getting higher and higher. The power transformer is one of the most critical power equipment in the power system, especially the large power transformer is not only expensive, but also has serious failure losses, and its normal operation will affect the safe and stable operation of the entire power system.

[0003] In the field work, most of the transformers in opera...

Examples

Embodiment Construction

[0057] The transformer excitation inrush current identification method based on the improved symbolic sequence entropy method includes the following steps:

[0058] Step 1: At a certain sampling frequency, according to N points per cycle, collect the secondary current of the current transformers on both sides of the differential protection of the transformer, and form a differential current signal sequence I 1 ={I 1 (1), I 1 (2),...,I 1 (k),...I 1 (N)}, k=1,2,...,N;

[0059] Step 2: Identify the differential current signal sequence I in step 1 1 Whether the value exceeds the setting value of the differential protection starting element, if it exceeds, the starting criterion is used to judge the fault differential current and the excitation inrush current;

[0060] Step 3: Initial signal sequence I for differential flow 1 Perform normalization processing so that all sampling points fall within the [0,1] interval, and obtain the differential flow signal sequence I 2 ={I ...

technical field

[0001] The invention belongs to the technical field of transformer differential protection, in particular to a transformer excitation inrush current identification method based on an improved symbol sequence entropy method. Background technique

[0002] In recent years, the power industry has made great progress. With the continuous production of ultra-high voltage, ultra-high voltage and large-capacity power transformers in my country, more and more long-distance power transmission systems are built and operated, so the requirements for the safety, stability and reliability of power systems are getting higher and higher. The power transformer is one of the most critical power equipment in the power system, especially the large power transformer is not only expensive, but also has serious failure losses, and its normal operation will affect the safe and stable operation of the entire power system.

[0003] In the field work, most of the transformers in opera...

Examples

Embodiment Construction

[0057] The transformer excitation inrush current identification method based on the improved symbolic sequence entropy method includes the following steps:

[0058] Step 1: At a certain sampling frequency, according to N points per cycle, collect the secondary current of the current transformers on both sides of the differential protection of the transformer, and form a differential current signal sequence I 1 ={I 1 (1), I 1 (2),...,I 1 (k),...I 1 (N)}, k=1,2,...,N;

[0059] Step 2: Identify the differential current signal sequence I in step 1 1 Whether the value exceeds the setting value of the differential protection starting element, if it exceeds, the starting criterion is used to judge the fault differential current and the excitation inrush current;

[0060] Step 3: Initial signal sequence I for differential flow 1 Perform normalization processing so that all sampling points fall within the [0,1] interval, and obtain the differential flow signal sequence I 2 ={I ...

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