A Risk Assessment Method for Switchgear Under Multi-Source Hybrid Signals

Abstract

The present invention discloses a risk assessment method for switchgear under multi-source hybrid signals. First, TEV sensors, wireless temperature sensors, and ultrasonic sensors are arranged on the outer side of the switchgear cabinet wall. The TEV sensors obtain the transient earth voltage signals generated by partial discharge, the ultrasonic sensors obtain the ultrasonic frequency signals generated by partial discharge, and the wireless temperature sensors obtain the temperature change information. Through the decomposition calculation of the transient earth voltage signals, ultrasonic frequency signals, and temperature change information, characteristic parameters are obtained, and then a preliminary judgment on the risk state of the switchgear is made. According to the risk judgment results, corresponding treatment measures are taken respectively. This method effectively improves the accuracy and reliability of the switchgear risk state assessment.

Description

Technical Field

[0001] The present invention relates to a method for risk assessment of internal faults in power equipment, and particularly to a risk assessment method for switchgear under multi-source hybrid signals. Background Art

[0002] With the rapid development of the distribution network of the power system, stable and reliable power supply has become the continuous pursuit of the distribution network power supply. High-voltage switchgear is widely used in the distribution network due to its reliable operation, convenient operation and other characteristics. However, due to improper operation or defects in the manufacturer's manufacturing process, internal faults of the switchgear are likely to occur, and even explosion accidents may be caused. Most of the existing methods only use a single physical quantity for risk assessment, and cannot accurately evaluate the risk state of the switchgear, which greatly limits the accuracy and reliability of the switchgear risk assessment. Therefore, the present invention comprehensively analyzes and processes various physical information in the switchgear, and proposes a risk assessment method for switchgear under multi-source hybrid signals. Summary of the Invention

[0003] In order to overcome the defects of the above background art, the present invention provides a risk assessment method for switchgear under multi-source hybrid signals, including the following steps:

[0004] The first step: Arrangement of sensors and wiring of devices

[0005] The experimental device includes a first ultrasonic sensor (1), a second ultrasonic sensor (2), a third ultrasonic sensor (3), a TEV sensor (4), a wireless temperature sensor (5), a host computer (6), an early warning component (7), and a power brake switch (8);

[0006] The first ultrasonic sensor (1) is installed on the front of the switchgear, the second ultrasonic sensor (2) is installed on the left side of the switchgear, and the third ultrasonic sensor (3) is installed on the right side of the switchgear, respectively located at the center positions of the front and left and right sides of the switchgear. Let the coordinates of the ultrasonic sensors be (x j , y j , z j ), j = 1, 2, 3; The TEV sensor is installed, and the TEV sensor (4) is installed at the center position on the top layer of the switchgear; The wireless temperature sensor (5) is installed at the center position on the reverse side of the switchgear. The first ultrasonic sensor (1), the second ultrasonic sensor (2), the third ultrasonic sensor (3) and the TEV sensor (4) are respectively connected to the host computer (6), and the host computer (6) is respectively connected to the early warning component (7) and the power brake switch (8). The wireless temperature sensor is connected to the host computer (6) through Ethernet;

[0007] The second step: Acquisition and processing of multi-source hybrid signals

[0008] The switchgear is in on-line operation, and three ultrasonic sensors are used to obtain the ultrasonic signal F generated by partial discharge j , and the time when the ultrasonic sensor receives the ultrasonic signal is t j , where j = 1, 2, 3;

[0009] Step 3: Acquisition of characteristic parameters

[0010] The calculation formula for the decomposition of the ultrasonic signal is as follows:

[0011]

[0012] In the formula, g(x) is the original signal, and g1(x), g2(x), …, g n (x) are the fundamental wave and harmonic signals;

[0013] Using the above formula, multi-scale hybrid decomposition is performed on the ultrasonic signals F1, F2, and F3 respectively to obtain three groups of fundamental wave and harmonic signals f 11 , f 12 , …, f 1n and f 21 , f 22 , …, f 2n and f 31 , f 32 , …, f 3n ;

[0014] Step 4: Preliminary judgment of fault risk

[0015] The transient earth voltage signal U(t) generated by partial discharge is obtained by the TEV sensor (4), and the peak time when the TEV sensor receives the transient earth voltage signal is recorded as t0;

[0016] The change of the temperature inside the switchgear with time t, T(t), is obtained by the wireless temperature sensor (5);

[0017] The acoustic coefficient matrix R of each ultrasonic sensor j The calculation formula is as follows:

[0018]

[0019] The risk assessment coefficient Q a The calculation formula is as follows:

[0020]

[0021] Q a ≤0.32, then there is no fault risk for the switchgear; 0.32 < Q a ≤0.8, then the switchgear is suspected of having a fault risk and needs to return to the second step to perform a risk assessment again; Q aIf it is > 0.8, there must be a fault risk in the switchgear, and further risk assessment and corresponding measures need to be taken;

[0022] Step 5: Fault risk assessment and treatment measures

[0023] Define the fault risk factor as follows:

[0024]

[0025] If η ≤ 0.45, the warning component will issue a warning to notify the staff to eliminate the fault risk; if η > 0.45, the power braking switch will act to cut off the power supply, and the warning component will issue a warning to notify the staff to eliminate the fault risk. Description of the drawings

[0026] Figure 1 It is the flow block diagram adopted by the method of the present invention.

[0027] Figure 2 It is the device drawing of the method of the present invention. Specific implementation manners

[0028] The present invention will be further described in detail below with reference to the drawings.

[0029] Step 1: Arrangement of sensors and wiring of the device

[0030] The experimental device includes a first ultrasonic sensor (1), a second ultrasonic sensor (2), a third ultrasonic sensor (3), a TEV sensor (4), a wireless temperature sensor (5), a host computer (6), a warning component (7), and a power braking switch (8);

[0031] Install the first ultrasonic sensor (1) on the front of the switchgear, install the second ultrasonic sensor (2) on the left side of the switchgear, and install the third ultrasonic sensor (3) on the right side of the switchgear, which are respectively located at the center positions of the front and the left and right sides of the switchgear. Let the coordinates of the ultrasonic sensors be (x j , y j , z j ), j = 1, 2, 3; Install the TEV sensor, and install the TEV sensor (4) at the center position on the top layer of the switchgear; Install the wireless temperature sensor (5) at the center position on the back of the switchgear. The first ultrasonic sensor (1), the second ultrasonic sensor (2), the third ultrasonic sensor (3), and the TEV sensor (4) are respectively connected to the host computer (6), and the host computer (6) is respectively connected to the warning component (7) and the power braking switch (8). The wireless temperature sensor is connected to the host computer (6) through Ethernet;

[0032] Step 2: Acquisition and processing of multi-source mixed signals

[0033] The switchgear is in on-line operation, and ultrasonic signals F generated by partial discharge are obtained by using 3 ultrasonic sensors j The moment when the ultrasonic sensor receives the ultrasonic signal is t j where j = 1, 2, 3;

[0034] Step 3: Acquisition of characteristic parameters

[0035] The calculation formula for the decomposition of ultrasonic signals is as follows:

[0036]

[0037] In the formula, g(x) is the original signal, and g1(x), g2(x), …, g n (x) are fundamental wave and harmonic signals;

[0038] Using the above formula, multi-scale hybrid decomposition is performed on ultrasonic signals F1, F2 and F3 respectively to obtain three groups of fundamental wave and harmonic signals f 11 、f 12 、…、f 1n and f 21 、f 22 、…、f 2n and f 31 、f 32 、…、f 3n ;

[0039] Step 4: Preliminary judgment of fault risk

[0040] The transient earth voltage signal U(t) generated by partial discharge is obtained by the TEV sensor (4), and the peak moment when the TEV sensor receives the transient earth voltage signal is recorded as t0;

[0041] The change of the temperature in the switchgear with time t is obtained by the wireless temperature sensor (5);

[0042] The acoustic coefficient matrix R of each ultrasonic sensor j The calculation formula is as follows:

[0043]

[0044] The risk assessment coefficient Q a The calculation formula is as follows:

[0045]

[0046] Q a ≤0.32, then there is no fault risk for the switchgear; 0.32 < Q a ≤0.8, then the switchgear is suspected of having a fault risk and needs to return to the second step to conduct a risk assessment again; Qa If η > 0.8, there must be a fault risk in the switch cabinet, and further risk assessment and corresponding measures need to be taken;

[0047] Step 5: Fault risk assessment and treatment measures

[0048] Define the fault risk factor as follows:

[0049]

[0050] If η ≤ 0.45, the warning component will issue a warning to notify the staff to eliminate the fault risk; if η > 0.45, the power brake switch will act to cut off the power supply, and the warning component will issue a warning to notify the staff to eliminate the fault risk.

Claims

1. A risk assessment method for switchgear under multi-source mixed signals, characterized in that It includes the following steps: The first step: Arrangement of sensors and wiring of the device The experimental device includes the first ultrasonic sensor (1), the second ultrasonic sensor (2), the third ultrasonic sensor (3), the TEV sensor (4), the wireless temperature sensor (5), the upper computer (6), the warning component (7), and the power brake switch (8); Install the first ultrasonic sensor (1) on the front of the switch cabinet, install the second ultrasonic sensor (2) on the left side of the switch cabinet, and install the third ultrasonic sensor (3) on the right side of the switch cabinet, which are respectively located at the center positions of the front and the left and right sides of the switch cabinet. Let the coordinates of the ultrasonic sensors be (x j , y j , z j ), where j = 1, 2, 3; Install the TEV sensor, and install the TEV sensor (4) at the center position on the top layer of the switch cabinet; Install the wireless temperature sensor (5) at the center position on the reverse side of the switch cabinet. The first ultrasonic sensor (1), the second ultrasonic sensor (2), the third ultrasonic sensor (3) and the TEV sensor (4) are respectively connected to the host computer (6), and the host computer (6) is respectively connected to the warning component (7) and the power brake switch (8). The wireless temperature sensor is connected to the host computer (6) through Ethernet; The second step: Acquisition and processing of multi-source mixed signals The switchgear is in on-line operation, and 3 ultrasonic sensors are used to obtain the ultrasonic signal F generated by partial discharge j , and the moment when the ultrasonic sensor receives the ultrasonic signal is t j , where j = 1, 2, 3; The third step: Acquisition of characteristic parameters The calculation formula for ultrasonic signal decomposition is as follows: where \(g(x)\) is the original signal, and \(g_1(x)\), \(g_2(x)\), \(\cdots\), \(g\) n (x) are the fundamental wave and harmonic signals; Perform multi-scale hybrid decomposition on the ultrasonic signals F1, F2, and F3 respectively using the above formula to obtain three groups of fundamental waves and harmonic signals f 11 , f 12 , …, f 1n and f 21 , f 22 , …, f 2n and f 31 , f 32 , …, f 3n ; The fourth step: Preliminary judgment of fault risk The transient earth voltage signal U(t) generated by partial discharge is obtained by the TEV sensor (4), and the peak moment when the TEV sensor receives the transient earth voltage signal is recorded as t0; The change of the temperature inside the switch cabinet with time t, T(t), is obtained by the wireless temperature sensor (5); The acoustic wave coefficient matrix R of each ultrasonic sensor j The calculation formula is as follows: Risk assessment coefficient Q a The calculation formula is as follows: Q a If Q ≤ 0.32, there is no fault risk for the switchgear; if 0.32 < Q a ≤ 0.8, there is a suspected fault risk for the switchgear and it is necessary to go back to the second step to conduct a risk assessment again; if Q a > 0.8, there must be a fault risk for the switchgear and it is necessary to further conduct a risk assessment and take corresponding measures; The fifth step: Fault risk assessment and treatment measures Define the fault risk factor as follows: If η ≤ 0.45, the warning component will issue a warning to notify the staff to eliminate the fault risk; if η > 0.45, the power brake switch will act to cut off the power supply, and the warning component will issue a warning to notify the staff to eliminate the fault risk.

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