A 110kV capacitor voltage transformer does not take out the lead test method

Abstract

The application discloses a kind of 110kV capacitor voltage transformer does not remove lead test method, comprising, by through-type current transformer, the test current flowing through primary lead is converted into secondary current;Utilize negative feedback amplification circuit to amplify the secondary current of the through-type current transformer, and the through-type current transformer is shielded and protected by full metal shield cover;The amplified through-type current transformer is connected into Xilin bridge, and the main capacitance, the voltage dividing capacitance, the main capacitor dielectric loss factor and the voltage dividing capacitor dielectric loss factor of the through-type current transformer are calculated.The application does not need to remove and restore high voltage lead, does not need high place operation, work intensity is greatly reduced, eliminates the risk of falling in high place operation;At the same time, accurate measurement of capacitance and dielectric loss can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of the power industry and electrical testing, and particularly relates to a 110kV capacitor voltage transformer non-disassembly lead test method. BACKGROUND

[0002] In the power system, according to the maintenance pre-test regulation requirements, the 110kV capacitor voltage transformer needs to be tested regularly, and the existing test method is to use a Xilin bridge to detect the test current flowing through the capacitor voltage transformer, so as to measure the capacitance and dielectric loss value of the capacitor voltage transformer.

[0003] However, when detecting the test current flowing through the capacitor voltage transformer, it is necessary to remove the primary lead by climbing operation, which results in low work efficiency, high risk of falling from a height for personnel, and potential equipment heating hazards caused by poor contact when removing and restoring the lead. SUMMARY

[0004] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the above existing problems, the present application is proposed.

[0006] Therefore, the present application provides a 110kV capacitor voltage transformer non-disassembly lead test method, which can avoid the personnel safety hazard problem of removing the primary lead by climbing operation when detecting the test current.

[0007] To solve the above technical problems, the present application provides the following technical scheme: comprising, converting the test current flowing through the primary lead into secondary current through the through-type current transformer; amplifying the secondary current by using a negative feedback amplification circuit, and shielding and protecting the through-type current transformer by using a full-metal shield cover; connecting the amplified through-type current transformer into a Xilin bridge, and calculating the main capacitance, the divided voltage capacitance, the main capacitor dielectric loss factor and the divided voltage capacitor dielectric loss factor of the through-type current transformer.

[0008] As a preferred scheme of the 110kV capacitor voltage transformer non-disassembly lead test method, the test current of the primary lead comprises,

[0009] I C1 = I XL -I C2

[0010] wherein, I C1The test current of the primary lead, I C2 The N-terminal current of the through-type current transformer primary lead, I XL The XL-terminal current of the through-type current transformer primary lead.

[0011] As a preferred scheme of the 110kV capacitor voltage transformer non-disassembly lead test method, the negative feedback amplification circuit includes, the input end of the negative feedback amplification circuit is connected to the N terminal, and the output end is connected to the instrument measurement line C x terminal.

[0012] As a preferred scheme of the 110kV capacitor voltage transformer non-disassembly lead test method, the negative feedback amplification circuit further includes, the bandwidth of the auxiliary operational amplifier satisfies:

[0013] F·ω1≤ω2≤ω3

[0014] Wherein, F is the power of the operational amplifier, ω1 is the open-loop unit gain bandwidth of the main operational amplifier, ω2 is the unit gain bandwidth of the auxiliary operational amplifier, and ω3 is the next pole frequency of the main operational amplifier.

[0015] As a preferred scheme of the 110kV capacitor voltage transformer non-disassembly lead test method, the amplified secondary current includes, the through-type current transformer is connected in parallel with the negative feedback amplification circuit, and the amplification multiple is equal to the transformation ratio Na of the through-type current transformer.

[0016] As a preferred scheme of the 110kV capacitor voltage transformer non-disassembly lead test method, the connection to the Westlin bridge includes, the fixed support end of the through-type current transformer is connected to the capacitor C1 end of the Westlin bridge, and the low-voltage secondary lead end of the through-type current transformer is connected to the N terminal of the Westlin bridge.

[0017] As a preferred scheme of the 110kV capacitor voltage transformer non-disassembly lead test method, the main capacitance includes, when the Westlin bridge is balanced:

[0018] C1=R4 / R3*C N

[0019] Wherein, C1 is the main capacitance of the through-type current transformer, R4 is a standard resistance arranged in the Westlin bridge, and R3 is an adjustable resistance arranged in the Westlin bridge.

[0020] As a preferred scheme of the 110kV capacitor voltage transformer non-disassembly lead test method, the main capacitance dielectric loss factor includes, when the Westlin bridge is balanced:

[0021] tgδ1= ωR4C4

[0022] Wherein, tgδ1 is the main capacitor dielectric loss factor, ω is the number of turns of the coil, C4 is the adjustable capacitor in the Wester bridge.

[0023] As a preferred scheme of the 110kV capacitor voltage transformer without dismounting the lead test method, wherein: the voltage dividing capacitor capacity includes, when the Wester bridge is balanced:

[0024]

[0025] Wherein, C2 is the voltage dividing capacitor capacity.

[0026] As a preferred scheme of the 110kV capacitor voltage transformer without dismounting the lead test method, wherein: the voltage dividing capacitor dielectric loss factor includes, when the Wester bridge is balanced:

[0027]

[0028] Wherein, tgδ2 is the voltage dividing capacitor dielectric loss factor.

[0029] The beneficial effects of the present application: without removing and restoring the high-voltage lead, without high-altitude operation, the work intensity is greatly reduced, and the falling risk of high-altitude operation is eliminated; at the same time, the precise measurement of the capacitance and the dielectric loss can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creating labor. Among them:

[0031] Figure 1 The flowchart of the 110kV capacitor voltage transformer without dismounting the lead test method according to the first embodiment of the present application;

[0032] Figure 2 The schematic diagram of the negative feedback amplification circuit connected for the 110kV capacitor voltage transformer without dismounting the lead test method according to the first embodiment of the present application;

[0033] Figure 3 The schematic diagram of the Wester bridge connected for the 110kV capacitor voltage transformer without dismounting the lead test method according to the first embodiment of the present application;

[0034] Figure 4The wiring schematic diagram for measuring C1 of the 110kV capacitive voltage transformer not disassembling the lead test method of the second embodiment of the present application is shown in the figure;

[0035] Figure 5 The wiring schematic diagram for measuring C2 of the 110kV capacitive voltage transformer not disassembling the lead test method of the second embodiment of the present application is shown in the figure;

[0036] Figure 6 The measurement principle schematic diagram for disassembling the lead of the 110kV capacitive voltage transformer not disassembling the lead test method of the second embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0037] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work should belong to the protection scope of the present application.

[0038] In the following description, a lot of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in other manners different from those described herein, and those skilled in the art can make similar generalizations without departing from the spirit and scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0039] Secondly, the "one embodiment" or "embodiment" referred to herein can include specific features, structures or characteristics contained in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0040] The present application is described in detail in combination with the schematic diagram. In the detailed description of the embodiments of the present application, the cross-sectional view of the device structure is locally enlarged without the general proportion for the convenience of description, and the schematic diagram is only an example, which should not limit the protection scope of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual manufacture.

[0041] Meanwhile, in the description of the present application, it should be noted that the terms "upper, lower, inner and outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first, second or third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0042] Unless otherwise expressly specified and limited, the terms "mounting, connecting, connecting" in the present application should be understood broadly, for example: it can be fixed connection, detachable connection or integral connection; it can also be mechanical connection, electrical connection or direct connection, it can also be indirectly connected through an intermediate medium, or it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] Embodiment 1

[0044] Reference Figures 1-3 For the first embodiment of the present application, the embodiment provides a 110kV capacitor voltage transformer without dismounting the lead test method, comprising:

[0045] S1: convert the test current flowing through the primary lead into secondary current through the through-type current transformer.

[0046] The through-type current transformer is connected from the top of the primary lead to the low-voltage secondary wiring end, and the primary lead of the through-type current transformer is connected to the XL end current and the reversed N end current, and the difference between the two is the current flowing through the primary lead end:

[0047] I C1 =I XL -I C2

[0048] Wherein, I C1 is the test current of the primary lead, I C2 is the reversed N end current connected to the primary lead of the through-type current transformer, and I XL is the current connected to the XL end of the primary lead of the through-type current transformer.

[0049] S2: amplify the secondary current of the through-type current transformer by using a negative feedback amplification circuit, and shield and protect the through-type current transformer by a full-metal shield.

[0050] Reference Figure 2 The input end of the negative feedback amplification circuit is connected to the N end, and the output end is connected to the instrument measurement line C x end.

[0051] The bandwidth of the auxiliary operational amplifier satisfies:

[0052] F·ω1≤ω2≤ω3

[0053] Wherein, F is the operational amplifier power, ω1 is the open-loop unit gain bandwidth of the main operational amplifier, ω2 is the unit gain bandwidth of the auxiliary operational amplifier, and ω3 is the next pole frequency of the main operational amplifier.

[0054] Since the current entering the Westlin bridge should be equal to the current I flowing through the device under test C1 , and the current on the secondary side of the through-type current transformer is I C1 / Na, Na is the transformation ratio of the through-type current transformer, therefore the secondary current needs to be amplified by Na times before entering the Westlin bridge; the through-type current transformer is connected in parallel with the negative feedback amplification circuit, and the amplification multiple is equal to the transformation ratio Na of the through-type current transformer.

[0055] And since the change in the phase of the current increases the test error of the dielectric loss value during the test, therefore the phase change cannot occur during the amplification of the secondary current

[0056] Preferably, a full-metal shield is used to shield and protect the through-type current transformer, eliminating the error of the through-type current transformer caused by electromagnetic field interference in the field operation environment.

[0057] S3: connecting the amplified through-type current transformer to the Westlin bridge to calculate the main capacitance, divided capacitance, main capacitance dielectric loss factor and divided capacitance dielectric loss factor of the through-type current transformer.

[0058] Referring to Figure 3 , the fixed support end of the through-type current transformer is connected to the capacitance C1 end of the Westlin bridge, and the low-voltage secondary wiring end of the through-type current transformer is connected to the N end.

[0059] Further, when the Westlin bridge is balanced, the main capacitance, divided capacitance, main capacitance dielectric loss factor and divided capacitance dielectric loss factor of the through-type current transformer are measured and calculated.

[0060] The main capacitance of the through-type current transformer is calculated as follows:

[0061] C1=R4 / R3*C N

[0062] Wherein, C1 is the main capacitance of the through-type current transformer, R4 is the standard resistance provided in the Westlin bridge, and R3 is the adjustable resistance provided in the Westlin bridge.

[0063] The main capacitance dielectric loss factor of the through-type current transformer is calculated as follows:

[0064] tgδ1=ωR4C4

[0065] Where tgδ1 is the dielectric loss factor of the main capacitor, ω is the number of coil turns, and C4 is the adjustable capacitor built into the Schering bridge.

[0066] The voltage divider capacitance of the feedthrough current transformer is calculated using the following formula:

[0067]

[0068] Where C2 is the voltage divider capacitance.

[0069] The dielectric loss factor of the voltage divider capacitor of the feedthrough current transformer is calculated using the following formula:

[0070]

[0071] Where tgδ2 is the dielectric loss factor of the voltage divider capacitor.

[0072] Example 2

[0073] To verify the effectiveness of the technology used in this method, this embodiment compares the traditional lead removal method with the method described herein, using scientific methods to compare the test results and verify the actual effectiveness of the method.

[0074] Traditional lead wire removal methods involve: high labor intensity for both removal and restoration; relatively secure lead wire connections; and workers need to work at heights. The entire process of removing and restoring lead wires is time-consuming. There is a high risk of personal injury, as extensive work at heights poses a significant risk of falls. Furthermore, there are potential equipment hazards, as corrosion of high-voltage lead wires during outdoor equipment operation can lead to insecure connections and equipment failure during restoration.

[0075] To verify that this method has higher measurement efficiency and accuracy compared to the traditional lead removal method, this embodiment will use the traditional lead removal method and this method to conduct real-time measurements and comparisons of the main capacitance, voltage divider capacitance, main capacitor dielectric loss factor, and voltage divider capacitor dielectric loss factor of a 110kV capacitive voltage transformer in a 110kV substation of Guizhou Power Grid Company.

[0076] Traditional lead removal methods involve grounding both the N and XL terminals during operation. However, during de-energization tests of capacitive voltage transformers, the high-voltage output line is grounded on both its local and opposite sides. A Schering bridge is used, employing a self-excitation method for testing. This requires removing the high-voltage output lead during the measurement process. The measurement principle is as follows: Figure 6 As shown, when the Schering bridge reaches equilibrium, the capacitance and dielectric loss parameters of C1 and C2 are measured; using this method, when the Schering bridge reaches equilibrium, the capacitance and dielectric loss parameters of C1 and C2 are measured, referring to... Figure 4 and Figure 5The measurement results are shown in Table 1.

[0077] Table 1: Comparison of the results of measuring the parameters of the capacitive voltage transformer by the method of removing the lead and the method of the present application.

[0078] Test method [C1(pF)] tg delta 1 [C2(pF)] tg delta 2 Overall error Time taken (minutes) Rated value 29980 0.07％ 69450 0.06％ / / Conventional method of removing the lead 29990 0.065％ 69530 0.055％ 0.1％ 46 The present method 29860 0.077％ 69550 0.053％ 0.12％ 6

[0079] As shown in the above table, the measurement error of the method of the present application meets the standard of measurement error ±0.2%, and is close to the measurement error of the traditional method of removing the lead. In addition, the measurement time is improved by 86.96% compared to the traditional method of removing the lead, thereby greatly reducing the equipment outage time.

[0080] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A test method for a 110kV capacitive voltage transformer without disconnecting the leads, characterized in that: include, The test current flowing through the primary lead is converted into a secondary current using a through-hole current transformer. The secondary current is amplified using a negative feedback amplifier circuit, and the through-core current transformer is shielded and protected by a full metal shield. Connect the enlarged current transformer to the Schering bridge and calculate the main capacitance, voltage divider capacitance, main capacitor dielectric loss factor, and voltage divider capacitor dielectric loss factor of the current transformer. The test current for the primary lead includes, I C1 =I XL -I C2 Among them, I C1 I is the test current of the primary lead. C2 For the primary lead of the current transformer, a reverse N-terminal current is connected, I XL The current connected to the XL terminal of the primary lead of the through-core current transformer; The negative feedback amplifier circuit includes, The input terminal of the negative feedback amplifier circuit is connected to the secondary terminal of the feedthrough current transformer, and the output terminal is connected to the instrument's measuring line C. x end; The negative feedback amplifier circuit also includes, The bandwidth of the auxiliary operational amplifier satisfies: F·ω1≤ω2≤ω3 Where F is the operational amplifier power, ω1 is the open-loop unity-gain bandwidth of the main operational amplifier, ω2 is the unity-gain bandwidth of the auxiliary operational amplifier, and ω3 is the secondary pole frequency of the main operational amplifier. The amplified secondary current includes, The secondary terminal of the through-hole current transformer is connected to the input terminal of the negative feedback amplifier circuit and is connected in series with the negative feedback amplifier circuit. The amplification factor is equal to the turns ratio Na of the through-hole current transformer. During the secondary current amplification process, no phase change must occur; The access to the Xilin bridge includes, The output of the negative feedback amplifier circuit is connected to the instrument measurement line C. x The terminal is connected to the Xilin bridge; The main power capacity includes, When the Schering bridge is balanced: C1=R4 / R3*C N Wherein, C1 is the main capacitance of the current transformer, R4 is the standard resistor in the Schering bridge, and R3 is the adjustable resistor in the Schering bridge. The dielectric loss factor of the main capacitor includes, When the Schering bridge is balanced: tgδ1=ωR4C4 Wherein, tgδ1 is the dielectric loss factor of the main capacitor, ω is the number of coil turns, and C4 is the adjustable capacitor built into the Schering bridge; The voltage divider capacitance includes, When the Schering bridge is balanced: Wherein, C2 is the voltage divider capacitance; The dielectric loss factor of the voltage divider capacitor includes, When the Schering bridge is balanced: Wherein, tgδ2 is the dielectric loss factor of the voltage divider capacitor.

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