CN211627687U - Online frequency domain dielectric spectrum detection system for high-voltage insulating sleeve - Google Patents
Online frequency domain dielectric spectrum detection system for high-voltage insulating sleeve Download PDFInfo
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- CN211627687U CN211627687U CN201921791075.0U CN201921791075U CN211627687U CN 211627687 U CN211627687 U CN 211627687U CN 201921791075 U CN201921791075 U CN 201921791075U CN 211627687 U CN211627687 U CN 211627687U
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Abstract
The utility model discloses an online frequency domain dielectric spectrum detecting system of high-voltage insulation sleeve relates to high-voltage insulation sleeve and detects technical field, to need generally in the test of frequency domain dielectric spectrum to applying frequency adjustable alternating voltage, the problem that is not suitable for the power equipment of online operation, adopts including high-voltage insulation sleeve, sleeve pipe end screen that awaits measuring, and the sleeve pipe end screen on the high-voltage insulation sleeve that awaits measuring passes through the wire and is connected with the earth. A wire connected with the ground passes through the Rogowski coil. The output end of the Rogowski coil is connected with one input end of the data acquisition and conversion module. And the other input end of the data acquisition and conversion module is connected with the voltage transformer through a wire. The output end of the data acquisition and conversion module is connected with the background analysis system. The utility model discloses need not be to applying frequency adjustable alternating voltage. And is therefore well suited for use in operating electrical equipment. The wiring is simple, the equipment is less, the cost is low, and the installation is convenient.
Description
Technical Field
The utility model relates to a high-voltage insulation sleeve detects technical field, in particular to high-voltage insulation sleeve online frequency domain dielectric spectrum detecting system.
Background
The oil-immersed high-voltage insulating sleeve is an important auxiliary safety device of a large-scale power transformer, and plays a role in leading out high-voltage and low-voltage leads inside the transformer from the transformer in the running process of the transformer, and the high-voltage insulating sleeve not only realizes the connection of the transformer and an external electric network, but also realizes the insulating effect of the leads of the transformer and a transformer shell. Under the special working conditions of electricity, heat, mechanical stress and the like in the long-term operation process of the sleeve and abnormal operation of equipment or environmental factors and the like, the phenomenon that the insulating property of oil paper insulation is reduced due to moisture and the like can occur, and the safe and stable operation of the equipment can be seriously influenced. According to statistics, the bushing fault is only second to the tap switch in the fault caused by the transformer accessory defect, and accounts for 35% -45% of the transformer electrical fault.
In the actual production at present, the damp state of the sleeve is judged mainly by monitoring the dielectric loss factor and the capacitance of the sleeve on line under the power frequency condition of the sleeve. However, the power frequency dielectric loss has less information carrying capacity and poorer sensitivity to moisture, and can be interfered by factors such as complex electromagnetic environment, temperature, insulation aging of the sleeve and the like in the field detection process, and once the dielectric loss value is obviously changed due to moisture, the sleeve often has serious problems. From the viewpoint of sensitivity and accuracy of online monitoring of transformer bushing insulation, an online monitoring method capable of effectively reflecting the bushing insulation condition is urgently needed.
In recent years, the frequency domain dielectric spectroscopy based on the dielectric response principle is gradually and widely applied to state evaluation of field oil paper insulation power equipment due to the advantages of nondestructive testing, rich contained information, strong anti-interference capability and the like. Researchers at home and abroad have conducted a great deal of research on the method and technology for applying frequency domain dielectric spectroscopy to the state detection of oil-immersed power equipment, and the research finds that the parameters of a frequency domain dielectric response curve have good sensitivity to factors such as temperature, moisture and aging degree, and can effectively reflect the change of the insulation state of oil paper. The frequency-domain dielectric spectroscopy is generally required to apply alternating voltage with adjustable frequency in the test, but is difficult to realize for power equipment running on line, which is the most main reason that the frequency-domain dielectric spectroscopy is not applied to the on-line monitoring of the power equipment.
SUMMERY OF THE UTILITY MODEL
In order to solve the above problem, the utility model discloses a following technical scheme realizes:
a high-voltage insulating sleeve online frequency domain dielectric spectrum detection system comprises a high-voltage insulating sleeve to be detected and a sleeve end screen, wherein the sleeve end screen on the high-voltage insulating sleeve to be detected is connected with the ground through a lead;
the wire connected with the ground penetrates through a Rogowski coil;
the output end of the Rogowski coil is connected with one input end of the data acquisition and conversion module;
the other input end of the data acquisition and conversion module is connected with a voltage transformer through a wire;
and the output end of the data acquisition and conversion module is connected with a background analysis system.
Preferably, the other input end of the data acquisition and conversion module is connected with the outer surface of the voltage transformer through a wire.
Preferably, the lead wire connected with the ground penetrates through a central wire passing hole of the Rogowski coil.
The utility model discloses the advantage only need increase some wires and sampling module and analytic system on existing equipment, just can realize data sampling, analysis, need not be to applying frequency adjustable alternating voltage. And is therefore well suited for use in operating electrical equipment. The wiring is simple, the equipment is less, the cost is low, and the installation is convenient.
Drawings
FIG. 1 is a schematic diagram of an on-line frequency domain dielectric spectrum detection system for a high voltage insulating bushing.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to fig. 1 of the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application. Thus, the following detailed description of the embodiments of the present application, as presented in the figures, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.
As shown in fig. 1, an online frequency domain dielectric spectrum detection system for a high-voltage insulating bushing includes a high-voltage insulating bushing to be detected 1, a bushing end screen 2, a rogowski coil 3, a voltage transformer 4, a data acquisition and conversion module (a/D)5, and a background analysis system 6. As shown in fig. 1, a bushing end screen 2 on a high-voltage insulating bushing 1 to be tested is connected with the ground through a wire, the wire penetrates through a rogowski coil 3, and an output end of the rogowski coil is connected with an input end of a data acquisition and conversion module (a/D) 5. In addition, the other input end of the data acquisition and conversion module (A/D)5 is connected with the outer surface of the voltage transformer 4 through a lead. The output end of the data acquisition and conversion module (A/D)5 is connected with the background analysis system 6. The background analysis system 6 is provided with analysis software, and the background analysis system 6 and the software are both in the prior art and can be directly purchased and used.
After the components are connected, the following steps are adopted for detecting 1 and obtaining voltage and current signals at the position of a high-voltage bushing; 2. calculating harmonic voltage and harmonic current at the high-voltage bushing; 3. calculating the complex capacitance of the main insulation of the bushing in a certain frequency band range according to the amplitude and phase relation; 4. calculating the frequency spectrum of the complex dielectric constant; 5. and completing the on-line monitoring of the frequency domain dielectric spectrum. To be able to illustrate more clearly how the voltage and current signals at the high voltage bushing are acquired and what means are required for sampling,
the station analysis system 6 obtains the voltage and current signals at the high-voltage bushing through the data acquisition and conversion module (a/D)5, and then performs fourier transform on the signals, so as to obtain voltage and current harmonic signals at various frequencies including fundamental waves. The following formula is used for calculation:
wherein U is0And I0Representing the amplitude, u, of the fundamental voltage and current, respectivelyx(t) and ix(t) steady state signals representing x harmonic voltage and current, respectively, AxAnd BxRespectively representing the proportionality coefficients, omega, between harmonic voltage and current and fundamental voltage and current signalsxRepresenting the angular frequency of the harmonic signal.
Then, if the angular frequency is ωxComplex capacitance C of casing oil paper insulation system*(ωx) Can be as follows:
C*(ωx)＝ix(t)/ux(t),(x＝0,1,2,…n)
the complex capacitance is calculated.
Then, the complex dielectric constant of the bushing oilpaper insulation system is calculated, and the frequency spectrum of the complex dielectric constant can be obtained:
*(ωx)＝C*(ωx)/jωxC0,(x＝0,1,2,…n)
wherein, C0The vacuum capacitance representing the insulation of the bushing can be calculated according to the parameters of the bushing.
Finally, the on-line monitoring of the frequency domain dielectric spectrum can be completed through the technology.
The utility model belongs to passive frequency domain dielectric spectrum on-line monitoring method utilizes harmonic voltage and harmonic current that appear on the sleeve pipe to calculate sleeve pipe oiled paper insulation complex capacitance and complex dielectric constant under the different frequencies, realizes the on-line monitoring of frequency domain dielectric spectrum. Since the birth of an alternating current power system, harmonic waves exist in the power system, and are increasing along with the increase of the number and the capacity of nonlinear equipment in the power system at present, which is an important phenomenon which is not negligible in the power system. Harmonic voltages of power systems are rich in high frequency components, typically higher harmonics of the fundamental frequency (50Hz) in integer multiples, the amplitude of which generally decreases with increasing frequency. And measuring steady-state voltage harmonic wave u (t) and steady-state current harmonic wave i (t) at the high-voltage bushing, calculating the complex capacitance of the main insulation of the bushing in a certain frequency band range according to the amplitude and phase relation of the harmonic wave u (t) and the steady-state current harmonic wave i (t), and further calculating the frequency spectrum of the complex dielectric constant of the bushing to realize the online monitoring of the frequency domain dielectric spectrum.
The steady state voltage harmonic u (t) refers to a voltage harmonic signal applied between a high-voltage guide rod of the bushing and a metal flange connected with the bushing and the transformer shell, and the steady state current harmonic i (t) refers to a current harmonic signal caused by the steady state voltage harmonic and flowing through the bushing oilpaper insulation system. The steady-state voltage harmonic is obtained from the voltage transformer, and the voltage transformer can accurately measure the steady-state voltage signal between the high-voltage lead wire and the ground without adding an additional voltage measuring device. And steady-state current harmonic waves are obtained from the end screen grounding wire, and a Rogowski coil is adopted to measure steady-state current harmonic wave signals on the end screen grounding wire.
As shown in fig. 1, the harmonic current and voltage monitoring information received by the background analysis system 6 from the data acquisition and conversion module 5 at a certain time is shown in table 1 (taking fundamental wave and 3, 5, and 7 th harmonics as examples).
TABLE 1 harmonic Voltage Current monitoring information
From the data in Table 1, the above expression for harmonic voltage current can be substituted according to the above formula:
u1(t)＝115.54×ej314t
u3(t)＝41.99×ej942t
u5(t)＝23.33×ej1570t
u7(t)＝18.66×ej2198t
i1(t)＝8.91×ej(314t+1.5545)
i3(t)＝7.18×ej(942t+1.5590)
i5(t)＝6.64×ej(1570t+1.5600)
i7(t)＝7.43×ej(2198t+1.5604)
the real and imaginary parts of the complex capacitance C x (ω x) at different frequencies are further calculated as shown in table 2.
TABLE 2 Complex real and imaginary capacitance calculation results
According to the structural size parameters of the main insulation system (capacitor core) of the monitored sleeve, the vacuum capacitance value C0 of the capacitor core is obtained through simulation calculation, namely 4.18231 multiplied by 10-11F, and the real part and the imaginary part of the complex dielectric constant are further calculated, as shown in table 3.
TABLE 3 calculation of real and imaginary parts of complex permittivity
The real and imaginary parts of the complex dielectric constant at other frequencies can be calculated according to the method, and then the discrete data of the dielectric constant frequency domain spectrum of the oil paper insulating sleeve in the wide frequency range similar to the table 3 can be obtained.
The utility model discloses the advantage only need increase some wires and sampling module and analytic system on existing equipment, just can realize data sampling, analysis, need not be to applying frequency adjustable alternating voltage. And is therefore well suited for use in operating electrical equipment. The wiring is simple, the equipment is less, the cost is low, and the installation is convenient.
Claims (3)
1. The utility model provides an online frequency domain dielectric spectrum detecting system of high-voltage insulation sleeve, includes high-voltage insulation sleeve (1), sleeve end screen (2) that awaits measuring, its characterized in that:
the sleeve end screen (2) on the high-voltage insulating sleeve (1) to be tested is connected with the ground through a lead;
the lead wire connected with the ground penetrates through a Rogowski coil (3);
the output end of the Rogowski coil (3) is connected with one input end of the data acquisition and conversion module (5);
the other input end of the data acquisition and conversion module (5) is connected with the voltage transformer (4) through a wire;
the output end of the data acquisition and conversion module (5) is connected with the background analysis system (6).
2. An on-line frequency domain dielectric spectroscopy detection system for a high voltage insulating bushing according to claim 1, wherein:
and the other input end of the data acquisition and conversion module (5) is connected with the outer surface of the voltage transformer (4) through a wire.
3. An on-line frequency domain dielectric spectroscopy detection system for a high voltage insulating bushing according to claim 1, wherein:
the lead wire connected with the ground penetrates through the central wire passing hole of the Rogowski coil (3).
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112798871A (en) * | 2020-12-07 | 2021-05-14 | 广西电网有限责任公司电力科学研究院 | Method for processing field reasons of dielectric loss value abnormity of oiled paper insulation capacitive bushing |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112798871A (en) * | 2020-12-07 | 2021-05-14 | 广西电网有限责任公司电力科学研究院 | Method for processing field reasons of dielectric loss value abnormity of oiled paper insulation capacitive bushing |
| CN112798871B (en) * | 2020-12-07 | 2023-03-14 | 广西电网有限责任公司电力科学研究院 | Method for processing field reasons of dielectric loss value abnormity of oiled paper insulation capacitive bushing |
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