Partial discharge detection method for inflatable switch cabinet

Abstract

The invention relates to a partial discharge detection method for an inflatable switch cabinet, and the method comprises the steps: collecting a suspension discharge signal in the cabinet, carrying out the frequency domain signal analysis of the discharge signal, and obtaining the frequency domain characteristics of the suspension discharge signal in the inflatable switch cabinet; acquiring suspension discharge signals outside the switch cabinet and analyzing frequency domain signals of the discharge signals to obtain frequency domain characteristics of the suspension discharge signals outside the inflatable switch cabinet; finally, whether partial discharge exists in the inflatable switch cabinet or not is judged, and if the PRPD atlas characteristics of the partial discharge conform to the suspension discharge characteristics, the measured signals are directly analyzed according to the frequency domain characteristics of the suspension discharge signals inside and outside the inflatable switch cabinet. According to the distribution characteristics of the signal frequency, the judgment and noise elimination of suspension discharge inside and outside the switch cabinet are realized, and the partial discharge detection rate, namely the accuracy, is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of partial discharge detection of electric equipment, in particular to a partial discharge detection method for a gas-filled switch cabinet. Background Art

[0002] In recent years, the technology of partial discharge detection through high-voltage sensors integrated in switch cabinets has shown its good detection effectiveness. This method can synchronize the signals of each phase in real time, thereby drawing a PRPD spectrum that is strictly synchronized with the signal, and can judge the type of partial discharge and the switch cabinet where it is located based on the spectrum. However, during the detection process, it was found that partial discharge signals outside the station, such as discharge in the cable, transformer discharge, and bus discharge outside the station, can be transmitted to the switch cabinet through the corresponding lines, and thus detected by the detection device, but the current detection method still lacks the ability to determine the location of partial discharge, that is, it is impossible to effectively determine whether partial discharge occurs inside the switch cabinet.

[0003] Therefore, in order to ensure the normal operation of the gas-filled switchgear equipment and timely discover the hidden dangers of partial discharge in the equipment, it is necessary to propose an effective discharge position determination method to eliminate the discharge outside the switchgear and improve the effectiveness of partial discharge detection in the switchgear. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a partial discharge detection method for a gas-filled switch cabinet, which can determine the suspended discharge inside and outside the switch cabinet and eliminate noise based on the distribution characteristics of the signal frequency.

[0005] The present invention solves the technical problem by adopting the following technical solutions: A partial discharge detection method for a gas-filled switchgear comprises the following steps: Step 1: Collect the suspended discharge signal in the cabinet, and analyze the frequency domain signal of the discharge signal to obtain the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet; Step 2: Collect the suspended discharge signal outside the cabinet, and analyze the frequency domain signal of the discharge signal to obtain the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet; Step 3: Determine whether there is partial discharge in the gas-filled switch cabinet. If the PRPD spectrum characteristics of the partial discharge are consistent with the characteristics of suspended discharge, the measured signal is directly analyzed according to the frequency domain characteristics of the suspended discharge signal inside and outside the gas-filled switch cabinet.

[0006] Moreover, the specific implementation method of step 1 is: placing a suspended discharge source inside the gas-filled switch cabinet, and arranging a partial discharge tester outside the gas-filled switch cabinet, connecting the placed suspended discharge source to the high-voltage signal, and discharging the suspended discharge source by applying a high-voltage power frequency voltage, using the partial discharge tester to collect partial discharge signals through a high-voltage sensor, and performing frequency domain signal analysis on the collected signals, the analysis method is the TF Map method, and the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet are obtained.

[0007] Moreover, the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet are as follows: when suspended discharge occurs in the cabinet, the signal is mainly distributed in the high frequency band, the highest frequency component reaches 20 MHz, and is concentrated in this frequency band.

[0008] Moreover, the specific implementation method of step 2 is: placing a suspended discharge source and a partial discharge tester outside the gas-filled switch cabinet, and connecting the suspended discharge source to the gas-filled switch cabinet through a 10kV or 35kV cable with a length of not less than 100m, using the same partial discharge detector as step 1 to measure outside the gas-filled switch cabinet, and applying the same voltage value as step 1 to cause the suspended discharge source to discharge; using the partial discharge tester to collect partial discharge signals through a high-voltage sensor, and performing frequency domain signal analysis on the collected signals, the analysis method is the TF Map method, and the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet are obtained.

[0009] Moreover, the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet are as follows: the concentrated signal distribution in the high frequency band disappears.

[0010] Moreover, the specific implementation method of step 3 is: determine whether there is partial discharge in the gas-filled switch cabinet. If the PRPD spectrum characteristics of the partial discharge meet the characteristics of suspended discharge, use the TF Map method to analyze the measured signal, and determine the partial discharge position based on the frequency domain characteristics of the suspended discharge signal inside and outside the gas-filled switch cabinet obtained in steps 1 and 2.

[0011] The advantages and positive effects of the present invention are: The present invention obtains the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet by collecting the suspended discharge signal in the cabinet and analyzing the frequency domain signal of the discharge signal; and obtains the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet by collecting the suspended discharge signal outside the cabinet and analyzing the frequency domain signal of the discharge signal; and finally determines whether there is partial discharge in the gas-filled switch cabinet. If the PRPD spectrum characteristics of the partial discharge meet the characteristics of suspended discharge, the measured signal is directly analyzed according to the frequency domain characteristics of the suspended discharge signal inside and outside the gas-filled switch cabinet. The present invention realizes the determination and noise elimination of the suspended discharge inside and outside the switch cabinet based on the distribution characteristics of the signal frequency, and improves the detection rate of partial discharge, that is, accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of suspended discharge signal measurement in a gas-filled switch cabinet of the present invention; Figure 2 This is a frequency domain characteristic diagram of the suspended discharge signal in the gas-filled switch cabinet of the present invention; Figure 3 Schematic diagram of the external suspended discharge signal measurement of the gas-filled switch cabinet of the present invention Figure 4 This is a frequency domain characteristic diagram of the external suspended discharge signal of the gas-filled switch cabinet of the present invention. DETAILED DESCRIPTION

[0013] The present invention is further described in detail below with reference to the accompanying drawings.

[0014] A partial discharge detection method for a gas-filled switchgear comprises the following steps: Step 1: Collect the suspended discharge signal in the cabinet, and analyze the frequency domain signal of the discharge signal to obtain the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet.

[0015] like Figure 1 As shown, a suspended discharge source is placed inside the gas-filled switch cabinet, and a partial discharge tester is arranged outside the gas-filled switch cabinet. The placed suspended discharge source is connected to the high-voltage signal, and the suspended discharge source is discharged by applying a high-voltage power frequency voltage. The partial discharge tester is used to collect partial discharge signals through a high-voltage sensor, and the collected signals are analyzed in the frequency domain. The analysis method is the TF Map method commonly used in the field of partial discharge detection, and the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet are obtained.

[0016] like Figure 2 As shown in the figure, the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet are as follows: when suspended discharge occurs in the cabinet, the signal is mainly distributed in the high frequency band, the highest frequency component can reach 20MHz, and is relatively concentrated in this frequency band.

[0017] Step 2: Collect the suspended discharge signal outside the cabinet, and analyze the frequency domain signal of the discharge signal to obtain the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet.

[0018] like Figure 3 As shown, the suspended discharge source and the partial discharge tester are placed outside the gas-filled switch cabinet, and the suspended discharge source is connected to the gas-filled switch cabinet through a 10 kV or 35 kV cable with a length of not less than 100 m. The same partial discharge detector as in step 1 is used to measure outside the gas-filled switch cabinet, and the same voltage value as in step 1 is applied to cause the suspended discharge source to discharge. The partial discharge tester is used to collect partial discharge signals through a high-voltage sensor, and the collected signals are analyzed in the frequency domain. The analysis method is the TF Map method, and the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet are obtained.

[0019] like Figure 4 As shown in the figure, the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet are: under the same discharge voltage, the concentrated signal distribution in the high frequency band disappears, which is caused by the large signal attenuation of the high frequency signal during the transmission process. Through the analysis of the frequency domain characteristics of the signal, it can be seen that the suspended discharge inside and outside the switch cabinet is quite different in the frequency domain, and this feature can be used to determine the suspended discharge inside and outside the cabinet.

[0020] Step 3: Determine whether there is partial discharge in the gas-filled switch cabinet. If the PRPD spectrum characteristics of the partial discharge are consistent with the characteristics of suspended discharge, the measured signal is directly analyzed according to the frequency domain characteristics of the suspended discharge signal inside and outside the gas-filled switch cabinet.

[0021] When measuring partial discharge of on-site gas-filled switch cabinets, first test whether there is partial discharge in the gas-filled switch cabinet. If the PRPD spectrum characteristics of the partial discharge meet the characteristics of suspended discharge, the measured signal can be directly analyzed using the TF Map method; then analyze the characteristics of its TF Map. If its frequency domain distribution characteristics meet the Figure 2 The frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet shown in the figure can be judged as suspended discharge in the cabinet. Figure 4 The frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet shown can be determined as a suspended discharge signal outside the cabinet, thereby eliminating interference outside the cabinet.

[0022] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A partial discharge detection method for a gas-filled switch cabinet, characterized in that: The following steps are involved: Step 1: Collect the suspended discharge signal in the cabinet, and analyze the frequency domain signal of the discharge signal to obtain the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet; Step 2: Collect the suspended discharge signal outside the cabinet, and analyze the frequency domain signal of the discharge signal to obtain the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet; Step 3: Determine whether there is partial discharge in the gas-filled switch cabinet. If the PRPD spectrum characteristics of the partial discharge are consistent with the characteristics of suspended discharge, the measured signal is directly analyzed according to the frequency domain characteristics of the suspended discharge signal inside and outside the gas-filled switch cabinet.

2. The partial discharge detection method for a gas-filled switch cabinet according to claim 1, characterized in that: The specific implementation method of step 1 is: placing a suspended discharge source inside the gas-filled switch cabinet, and arranging a partial discharge tester outside the gas-filled switch cabinet, connecting the placed suspended discharge source to a high-voltage signal, and discharging the suspended discharge source by applying a high-voltage power frequency voltage, using the partial discharge tester to collect partial discharge signals through a high-voltage sensor, and performing frequency domain signal analysis on the collected signals, the analysis method is the TF Map method, and the frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet are obtained.

3. The partial discharge detection method for a gas-filled switch cabinet according to claim 2, characterized in that: The frequency domain characteristics of the suspended discharge signal in the gas-filled switch cabinet are as follows: when suspended discharge occurs in the cabinet, the signal is mainly distributed in the high frequency band, the highest frequency component reaches 20 MHz, and is concentrated in this frequency band.

4. The partial discharge detection method for a gas-filled switch cabinet according to claim 2, characterized in that: The specific implementation method of step 2 is: placing a suspended discharge source and a partial discharge tester outside the gas-filled switch cabinet, and connecting the suspended discharge source to the gas-filled switch cabinet through a 10kV or 35kV cable with a length of not less than 100m, using the same partial discharge detector as in step 1 to measure outside the gas-filled switch cabinet, and applying the same voltage value as in step 1 to cause the suspended discharge source to discharge; using the partial discharge tester to collect partial discharge signals through a high-voltage sensor, and performing frequency domain signal analysis on the collected signals, the analysis method is the TF Map method, and the frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet are obtained.

5. The partial discharge detection method for a gas-filled switch cabinet according to claim 4, characterized in that: The frequency domain characteristics of the suspended discharge signal outside the gas-filled switch cabinet are as follows: the concentrated signal distribution in the high frequency band disappears.

6. The partial discharge detection method for a gas-filled switch cabinet according to claim 1, characterized in that: The specific implementation method of step 3 is: determine whether there is partial discharge in the gas-filled switch cabinet. If the PRPD spectrum characteristics of the partial discharge meet the characteristics of suspended discharge, use the TF Map method to analyze the measured signal, and determine the partial discharge position based on the frequency domain characteristics of the suspended discharge signal inside and outside the gas-filled switch cabinet obtained in steps 1 and 2.

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