An intelligent reclosing system based on transformer vibration characteristics during short-circuit faults

Abstract

The present invention discloses an intelligent reclosing system based on the vibration characteristics of the transformer during a short-circuit fault. The present invention includes a vibration state sensing module, a transformer current acquisition module, a short-circuit current resistance capability evaluation module and a locking signal output module; the vibration state sensing module collects the transformer body vibration signal; the transformer current acquisition module collects the current values ​​on each side of the transformer; the short-circuit current resistance capability evaluation module analyzes the transformer body vibration information and the current on each side of the transformer, obtains the transformer tolerance current value, and makes real-time decisions on the reclosing function of the transformer lower line protection device; the locking signal output module interfaces with the transformer lower line protection device to transmit the reclosing locking signal. The present invention avoids damage to the main transformer caused by the short-circuit impact of the reclosing switch, thereby improving the system power supply reliability.

Description

Technical Field

[0001] The invention relates to the field of power transformers, and in particular to an intelligent reclosing system based on transformer vibration characteristics during short-circuit faults. Background Art

[0002] About 90% of short-circuit faults in power systems are transient single-phase grounding faults. After the relay protection action removes the short-circuit fault, the arc will automatically extinguish, and in most cases the insulation at the short-circuit point can be automatically restored. Automatic reclosing technology can quickly restore system power supply after the fault is removed and improve the transient stability level of the power system. It is an important safety automatic control method for the power system.

[0003] However, with the increasing system capacity, equipment and number of lines, the number of short-circuit impact currents suffered by power transformers, as the hub equipment of the power system, increases accordingly. The short-circuit impact of the reclosing switch has a greater impact on the mechanical stability of the transformer. The failure of main transformer damage and tripping due to short-circuit impact of line reclosing switch or even multiple reclosing shocks accounts for about 25% of all transformer accidents, seriously affecting the safe and stable operation of the equipment.

[0004] The vibration signal of the power transformer is an important feature that reflects the transformer's ability to resist short circuits during operation. The vibration signal of the transformer during stable operation mainly comes from the vibration of the core and winding. When the transformer is impacted by a short circuit fault, the winding modal characteristics change, the natural frequency changes, and under the joint excitation of the core and the electric force, the winding vibration signal and the vibration characteristics of the oil tank surface will change. The vibration signal of the winding changes can be used to evaluate the short circuit resistance of the power transformer. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides an intelligent reclosing system based on the vibration characteristics of the transformer during a short-circuit fault, which comprehensively considers the safety of the main equipment and the reliability of the system power supply, and adopts the intelligent reclosing technology based on the vibration characteristics of the transformer during a short-circuit fault to make a real-time judgment on the transformer's ability to resist short-circuit current. If the fault current exceeds the transformer's ability to withstand short-circuit current, the reclosing function of the main transformer's downstream line protection device is locked to avoid damage to the main transformer caused by the short-circuit impact of the reclosing; if the fault current is less than the transformer's ability to withstand short-circuit current, the reclosing function of the main transformer's downstream line protection device is opened to improve the system power supply reliability.

[0006] The present invention adopts the following technical solution: an intelligent reclosing system based on the vibration characteristics of the transformer during a short-circuit fault, which includes a vibration state sensing module, a transformer current acquisition module, a short-circuit current resistance capability evaluation module and a locking signal output module;

[0007] The vibration state sensing module uses a vibration sensor installed on the transformer body to obtain a vibration signal of the transformer body;

[0008] The transformer current collection module is connected to the current transformers installed on each side of the transformer to collect the current on each side of the transformer;

[0009] The short-circuit current resistance evaluation module receives the transformer body vibration signal and processes it to obtain the current short-circuit current tolerance value of the transformer, compares the short-circuit current tolerance value with the current values ​​on each side of the transformer collected, and makes real-time decisions on the switching on and off of the reclosing function of the transformer's lower-level line protection device; if the short-circuit current tolerance value is less than or equal to the current values ​​on each side of the transformer, the reclosing switch is locked; if the short-circuit current tolerance value is greater than the current values ​​on each side of the transformer, the reclosing switch is opened;

[0010] The locking signal output module receives the reclosing function activation and deactivation command issued by the short-circuit current resistance capability evaluation module, and sends it to the transformer downstream line protection device.

[0011] Furthermore, in the short-circuit current resistance evaluation module, the specific process of obtaining the current short-circuit current tolerance value of the transformer is as follows:

[0012] Collect vibration signals, calculate the harmonic content, and obtain the content of each harmonic as p1, p2, ... p i …p n , n is the harmonic order, p i is the i-th harmonic content;

[0013] Calculate the spectral weighted information entropy H of the vibration signal as follows:

[0014]

[0015] Where η i is the weighting coefficient of the i-th harmonic;

[0016] The short-circuit withstand current value of the transformer is calculated according to the spectrum weighted information entropy.

[0017] Furthermore, the weighting coefficient is determined by a short-circuit impact test, and the corresponding relationship between the degree of mechanical damage to the winding and the vibration frequency is obtained by analyzing the vibration signal data of a large number of transformer short-circuit impact tests, and the correlation coefficient between mechanical stability and characteristic harmonics is extracted.

[0018] Furthermore, the mechanical stability is measured by the damage degree value, and each group of tests obtains a mechanical damage degree value B of a winding. j And the content of different harmonics of the vibration signal p ij , j is the test number;

[0019] For the i-th harmonic, calculate {B1, B2, ..., B j , …, B K} and {p i1 , p i2 ,…,p ij ,…,p iK The correlation coefficient R i , which is the correlation coefficient between mechanical stability and characteristic harmonics.

[0020] Furthermore, the larger the correlation coefficient is, the higher the weighted coefficient is assigned, and the sum of the weighted coefficients of each harmonic is 1;

[0021] The weighting coefficient η of the i-th harmonic i =aR i , a is a constant, satisfying aR1+aR2+…aR K =1.

[0022] Furthermore, the relationship between the short-circuit withstand current value and the spectrum weighted information entropy is an inversely proportional relationship. If the spectrum weighted information entropy is larger, the short-circuit withstand current value is smaller.

[0023] Furthermore, the short-circuit withstand current value I is determined by the following constraint relationship:

[0024] I 2 +H 2 =S (2)

[0025] Where S is the setting threshold, which is set according to the actual project.

[0026] Furthermore, the interface between the blocking signal output module and the line protection device includes a conventional switch quantity interface and a digital GOOSE interface.

[0027] The present invention has the following beneficial effects: the present invention realizes the intelligent switching on and off of the reclosing function of the lower-level line protection device of the main transformer by collecting the transformer vibration signal and the current value on each side of the transformer. If the transformer withstand current value obtained through the transformer vibration signal is greater than the current value on each side of the transformer, the reclosing function of the lower-level line protection device of the transformer is opened; if the transformer withstand current value obtained through the transformer vibration signal is greater than the current value on each side of the transformer, the reclosing function of the lower-level line protection device of the transformer is locked. The present invention can effectively avoid damage to the main transformer caused by the short-circuit impact of the reclosing switch, and improve the power supply reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0029] Figure 1It is a structural schematic diagram of an intelligent reclosing system based on the vibration characteristics of a transformer during a short-circuit fault in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments.

[0031] like Figure 1 An intelligent reclosing system based on the vibration characteristics of the transformer during a short-circuit fault is shown, comprising a vibration state sensing module, a transformer current acquisition module, a short-circuit current resistance capability evaluation module and a locking signal output module.

[0032] The vibration state sensing module uses the vibration sensor installed on the transformer body to obtain the original vibration signal of the transformer body, which is processed by the vibration state sensing module and sent to the short-circuit current resistance capability evaluation module.

[0033] The transformer current acquisition module is connected to the current transformers installed on each side of the transformer, collects the current on each side of the transformer, and sends it to the short-circuit current capability evaluation module; the transformer current acquisition module also has analog current sampling value and digital current sampling value interface.

[0034] The short-circuit current resistance capability assessment module receives the transformer body vibration signal, calculates its spectrum weighted information entropy, and calculates the current short-circuit current tolerance value of the transformer according to the constraint relationship between the spectrum weighted information entropy and the short-circuit current tolerance value, and compares the short-circuit current tolerance value with the collected current values ​​on each side of the transformer. If the short-circuit current tolerance value is less than or equal to the current value on each side of the transformer, a valid locking reclosing signal is sent to the transformer medium and low voltage side outgoing line protection device through the locking signal output module; if the short-circuit current tolerance value is greater than the current value on each side of the transformer, a valid opening reclosing signal is sent to the transformer medium and low voltage side outgoing line protection device through the locking signal output module.

[0035] In the short-circuit current resistance evaluation module, the specific process of obtaining the current short-circuit current tolerance value of the transformer is as follows:

[0036] Collect vibration signals, calculate the harmonic content, and obtain the content of each harmonic as p1, p2, ... p i …p n , n is the harmonic order, p i is the i-th harmonic content;

[0037] Calculate the spectral weighted information entropy H of the vibration signal as follows:

[0038]

[0039] Where ηi is the weighting coefficient of the i-th harmonic.

[0040] The short-circuit withstand current value of the transformer is calculated according to the spectrum weighted information entropy.

[0041] The weighted coefficient is determined by a short-circuit impact test. The corresponding relationship between the degree of mechanical damage to the winding and the vibration frequency is obtained by analyzing the vibration signal data of a large number of transformer short-circuit impact tests, and the correlation coefficient between the mechanical stability and the characteristic harmonic is extracted.

[0042] The mechanical stability is measured by the damage degree value. Each test group obtains a mechanical damage degree value B of a winding. j And the content of different harmonics of the vibration signal p ij , j is the test number;

[0043] For the i-th harmonic, calculate {B1, B2, ..., B j , …, B K} and {p i1 , p i2 ,…,p ij ,…,p iK The correlation coefficient R i , which is the correlation coefficient between mechanical stability and characteristic harmonics.

[0044] The larger the correlation coefficient is, the higher the weighting coefficient is assigned, and the sum of the weighting coefficients of each harmonic is 1; the weighting coefficient η of the i-th harmonic is i =aR i , a is a constant, satisfying aR1+aR2+…aR K =1.

[0045] The relationship between the short-circuit withstand current value and the spectrum weighted information entropy is inversely proportional. The larger the spectrum weighted information entropy, the smaller the short-circuit withstand current value. The short-circuit withstand current value I is determined by the following constraint relationship:

[0046] I 2 +H 2 =S (2)

[0047] Where S is the setting threshold, which is set according to the actual project.

[0048] The locking signal output module receives the locking reclosing command issued by the short-circuit current capability evaluation module and sends it to the medium and low voltage side outgoing line protection device of the transformer. The locking signal output module and the line protection device interface are compatible with both conventional switch quantity interface and digital GOOSE interface.

[0049] Those skilled in the art to which the present invention relates may make various modifications or additions to the specific embodiments described or replace them in a similar manner, but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.

Claims

1. An intelligent reclosing system based on the vibration characteristics of transformers during short-circuit faults, characterized in that: It includes vibration state sensing module, transformer current acquisition module, short-circuit current capability assessment module and locking signal output module; The vibration state sensing module uses a vibration sensor installed on the transformer body to obtain a vibration signal of the transformer body; The transformer current collection module is connected to the current transformers installed on each side of the transformer to collect the current on each side of the transformer; The short-circuit current resistance evaluation module receives the transformer body vibration signal and processes it to obtain the current short-circuit current tolerance value of the transformer, compares the short-circuit current tolerance value with the collected current values ​​on each side of the transformer, and makes real-time decisions on the switching on and off of the reclosing function of the transformer's lower-level line protection device; if the short-circuit current tolerance value is less than or equal to the current value on each side of the transformer, the reclosing switch is locked; if the short-circuit current tolerance value is greater than the current value on each side of the transformer, the reclosing switch is opened; The locking signal output module receives the reclosing function throw-in and throw-out command issued by the short-circuit current resistance capability evaluation module, and sends it to the transformer lower-level line protection device; In the short-circuit current resistance evaluation module, the specific process of obtaining the current short-circuit current tolerance value of the transformer is as follows: Collect vibration signals, calculate the harmonic content, and obtain the content of each harmonic as p1, p2, ... p i …p n , n is the harmonic order, p i is the i-th harmonic content; Calculate the spectral weighted information entropy H of the vibration signal as follows: Where η i is the weighting coefficient of the i-th harmonic; The short-circuit withstand current value of the transformer is calculated according to the spectrum weighted information entropy.

2. The intelligent reclosing system based on transformer vibration characteristics during short-circuit fault according to claim 1, characterized in that: The weighted coefficient is determined by a short-circuit impact test. The corresponding relationship between the degree of mechanical damage to the winding and the vibration frequency is obtained by analyzing the vibration signal data of a large number of transformer short-circuit impact tests, and the correlation coefficient between the mechanical stability and the characteristic harmonic is extracted.

3. The intelligent reclosing system based on transformer vibration characteristics during short-circuit fault according to claim 2, characterized in that: The mechanical stability is measured by the damage degree value. Each test group obtains a mechanical damage degree value B of a winding. j And the content of different harmonics of the vibration signal p ij , j is the test number; For the i-th harmonic, calculate {B1, B2, ..., B j , …, B K } and {p i1 , p i2 ,…,p ij ,…,p iK The correlation coefficient R i , which is the correlation coefficient between mechanical stability and characteristic harmonics.

4. The intelligent reclosing system based on transformer vibration characteristics during short-circuit fault according to claim 3, characterized in that: The larger the correlation coefficient is, the higher the weighting coefficient is assigned, and the sum of the weighting coefficients of each harmonic is 1; The weighting coefficient η of the i-th harmonic i =aR i , a is a constant, satisfying aR1+aR2+…aR K =1.

5. The intelligent reclosing system based on transformer vibration characteristics during short-circuit fault according to claim 1, characterized in that: The relationship between the short-circuit withstand current value and the spectrum weighted information entropy is an inversely proportional relationship. If the spectrum weighted information entropy is larger, the short-circuit withstand current value is smaller.

6. The intelligent reclosing system based on transformer vibration characteristics during short-circuit fault according to claim 4, characterized in that: The short-circuit withstand current value I is determined by the following constraint relationship: I 2 +H 2 =S (2) Where S is the setting threshold, which is set according to the actual project.

7. The intelligent reclosing system based on transformer vibration characteristics during short-circuit fault according to claim 1, characterized in that: The blocking signal output module and the line protection device interface are compatible with both conventional switch quantity interfaces and digital GOOSE interfaces.

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