A high-frequency signal acquisition and processing system for pole-mounted circuit breakers

Abstract

The present invention discloses a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker, which relates to the field of relay protection technology and traveling wave ranging of a power system. The system comprises: a voltage acquisition module: used for acquiring high-frequency traveling wave signals of a distribution line based on a signal acquisition component built into the pole-mounted circuit breaker; a current acquisition module: used for acquiring a secondary-side induced electromotive force signal corresponding to a primary current based on the signal acquisition component, and obtaining a secondary-side induced electromotive force output waveform based on the secondary-side induced electromotive force signal; a signal processing module: used for processing the high-frequency traveling wave signal based on the signal processing component to obtain a secondary output waveform of the high-frequency traveling wave signal, and locating the fault point of the distribution line based on the secondary output waveform and the secondary-side induced electromotive force output waveform. The system can solve the problem that the pole-mounted circuit breaker cannot acquire high-frequency traveling wave signals and that the traditional high-frequency traveling wave signal acquisition device is usually designed as a complete machine, and the line access is cumbersome and costly.

Description

Technical Field

[0001] The invention relates to the field of relay protection technology and traveling wave ranging of power systems, and in particular to a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker. Background Art

[0002] With the continuous development of power systems and the large-scale commissioning of power equipment, modern distribution networks have gradually become more complex systems. How to quickly find and eliminate faults when a fault occurs in the line has become one of the main research topics for improving the safety and reliability of power supply in distribution networks. Currently, traveling wave ranging technology is commonly used to locate the fault point of the line. The accuracy of the collected traveling wave data determines the accuracy of the fault point location.

[0003] Currently available distribution network equipment and terminals, especially pole-mounted circuit breakers, as commonly used equipment in distribution networks, generally do not have the function of high-frequency traveling wave signal acquisition. The high-frequency traveling wave signal acquisition devices that can be used in distribution networks are usually designed as a whole machine, which is cumbersome to operate when the line is connected. In addition, large-scale investment in high-frequency traveling wave signal devices for distribution networks will result in huge costs. To a certain extent, high-frequency traveling wave signal devices may even affect the normal operation and maintenance of the distribution network. Summary of the invention

[0004] In order to solve the problem that the pole-mounted circuit breaker cannot collect high-frequency traveling wave signals and the traditional high-frequency traveling wave signal collection device is usually designed as a whole machine, the line access operation is complicated and the cost is high, the present invention provides a high-frequency signal collection and processing system for a pole-mounted circuit breaker, the system comprising:

[0005] Voltage acquisition module: used to collect high-frequency traveling wave signals of distribution lines based on the signal acquisition components built into the pole-mounted circuit breaker;

[0006] Current acquisition module: used for acquiring a secondary-side induced electromotive force signal corresponding to the primary current based on the signal acquisition component, and obtaining a secondary-side induced electromotive force output waveform based on the secondary-side induced electromotive force signal;

[0007] Signal processing module: used to process the high-frequency traveling wave signal based on the signal processing component to obtain the secondary output waveform of the high-frequency traveling wave signal, and locate the fault point of the distribution line based on the secondary output waveform and the secondary side induced electromotive force output waveform.

[0008] The voltage acquisition module acquires the high-frequency traveling wave signal of the distribution line through the signal acquisition component built into the pole-mounted circuit breaker. The current acquisition module acquires the secondary-side induced electromotive force signal corresponding to the primary current through the signal acquisition component, and then obtains the secondary-side induced electromotive force output waveform based on the secondary-side induced electromotive force signal. The voltage acquisition module transmits the high-frequency traveling wave signal to the signal processing module. The signal processing module processes the high-frequency traveling wave signal through the signal processing component to obtain the secondary output waveform of the high-frequency traveling wave signal, and then locates the fault point of the distribution line based on the secondary output waveform and the secondary-side induced electromotive force output waveform. This system acquires the high-frequency signal of the distribution line through the signal acquisition component built into the pole-mounted circuit breaker, which solves the problem that the pole-mounted circuit breaker cannot acquire the high-frequency traveling wave signal. At the same time, the signal acquisition component is built into the pole-mounted circuit breaker and combined with the pole-mounted circuit breaker. The line access is simple, and no additional high-frequency traveling wave signal acquisition device is required, which reduces the cost.

[0009] In order to accurately obtain the high-frequency traveling wave signal of the distribution line and ensure that the installation of the signal acquisition component does not affect the function and accuracy of the voltage transformer of the pole-mounted circuit breaker itself, the signal acquisition component of this system adopts the voltage transformer of the pole-mounted circuit breaker itself, and adds a resistor-capacitor voltage-dividing type electronic transformer on its basis. The voltage transformer is connected to the resistor-capacitor voltage-dividing type electronic transformer, and the resistor-capacitor voltage-dividing type electronic transformer is used to collect the high-frequency traveling wave signal of the distribution line. The resistor-capacitor voltage-dividing type electronic transformer is used to modify the voltage transformer. The phase and difference ratios of the voltage transformer change slightly, which does not affect the function and accuracy of the voltage transformer, thereby achieving the collection of high-frequency signals without affecting the function and accuracy of the pole-mounted circuit breaker itself.

[0010] Furthermore, the signal acquisition component includes a voltage transformer and a resistor-capacitor voltage divider type electronic transformer, the input end of the voltage transformer is connected to the incoming line side of the pole-mounted circuit breaker, the output end of the voltage transformer is connected to the outgoing line side of the pole-mounted circuit breaker, the voltage transformer includes a high-voltage arm capacitor C1 and a low-voltage arm capacitor C2, the positive electrode of the high-voltage arm capacitor C1 is connected to the input end of the voltage transformer, the negative electrode of the high-voltage arm capacitor C1 is connected to the positive electrode of the low-voltage arm capacitor C2, the negative electrode of the low-voltage arm capacitor C2 is connected to the input end of the resistor-capacitor voltage divider type electronic transformer, and the ground end of the resistor-capacitor voltage divider type electronic transformer is grounded.

[0011] Furthermore, the RC voltage divider type electronic transformer includes a RC voltage divider plate, a varistor, a sampling capacitor C and a sampling resistor R1. The varistor, the sampling capacitor C and the sampling resistor R1 are connected in parallel. The input ends of the varistor, the sampling capacitor C and the sampling resistor R1 are all connected to the input end of the RC voltage divider plate, and the output ends of the varistor, the sampling capacitor C and the sampling resistor R1 are all connected to the output end of the RC voltage divider plate.

[0012] In order to more accurately locate the fault point of the distribution line and not affect the design structure and accuracy of the current transformer of the pole-mounted circuit breaker itself, the signal acquisition component of this system also uses the current transformer of the pole-mounted circuit breaker itself, and adds a sampling resistor on its basis. The current transformer is connected in parallel with the sampling resistor, and the secondary side induced electromotive force signal corresponding to the primary current on the sampling resistor is collected. The change of the primary current of the distribution line is reflected based on the secondary side induced electromotive force signal. The fault point of the distribution line can be more accurately located through its change and the high-frequency traveling wave signal. The current transformer and the sampling resistor are connected in parallel, and the current value of the primary current flowing through the current transformer remains unchanged, which does not affect the design structure and accuracy of the current transformer of the pole-mounted circuit breaker itself.

[0013] The secondary side output terminal of the current transformer is connected in parallel with the sampling resistor, and the secondary side induced electromotive force signal corresponding to the primary current on the sampling resistor is collected.

[0014] Furthermore, the signal acquisition component also includes a current transformer and a sampling resistor R2, the input end of the current transformer is connected to the input end of the pole-mounted circuit breaker, the output end of the current transformer is connected to the output end of the pole-mounted circuit breaker, one end of the secondary side terminal of the current transformer is connected to one end of the sampling resistor R2, and the other end of the secondary side terminal of the current transformer is connected to the other end of the sampling resistor R2.

[0015] In order to make the high-frequency traveling wave signal clearer and more accurate, the system also adds a signal processing component, which includes a filtering circuit, an amplifying circuit, a multi-channel differential amplifying circuit and a sampling chip. The filtering circuit can filter out unnecessary peaks in the high-frequency traveling wave signal to make it more accurate. The amplifying circuit and the multi-channel differential amplifying circuit can amplify the high-frequency traveling wave signal to make its waveform clearer. The sampling chip can collect and process the secondary output waveform obtained.

[0016] Furthermore, the signal processing component includes a filtering circuit, an amplifying circuit, a multi-channel differential amplifying circuit and a sampling chip. The input end of the filtering circuit is connected to the output end of the RC voltage divider type electronic transformer, the output end of the filtering circuit is connected to the input end of the amplifying circuit, the output end of the amplifying circuit is connected to the input end of the multi-channel differential amplifying circuit, the output end of the multi-channel differential amplifying circuit is connected to the input end of the sampling chip, and the output end of the sampling chip is used to connect to a waveform displayer.

[0017] Furthermore, the RC voltage divider type electronic transformer is used to collect the high-frequency traveling wave signal of the distribution line.

[0018] Furthermore, the secondary-side induced electromotive force signal corresponding to the primary current is obtained based on the sampling resistor R2.

[0019] In order to further locate the fault point of the distribution line through the change of the secondary output waveform, the system also obtains the voltage U3 of the high-frequency traveling wave signal based on the signal acquisition component, and then obtains the voltage U4 of the secondary output waveform based on the voltage U3, and judges the change of the secondary output waveform through the change of the voltage U4, so as to further accurately locate the fault point of the distribution line.

[0020] Furthermore, the voltage acquisition module is also used to obtain the voltage U3 of the high-frequency traveling wave signal and the output voltage U1 of the voltage transformer based on the signal acquisition component; obtain the voltage U4 of the secondary output waveform based on the voltage U3, and the output voltage U1 and the voltage U4 are used to reflect the change of the secondary output waveform; the specific steps of obtaining the voltage U3 of the high-frequency traveling wave signal and the output voltage U1 of the voltage transformer based on the signal acquisition component include: obtaining the input voltage U of the distribution line; obtaining the equivalent capacitance C3 of the resistor-capacitor voltage divider type electronic transformer based on the high-voltage arm capacitance C1 and the low-voltage arm capacitance C2; ​​obtaining the output voltage U1 based on the input voltage U, the high-voltage arm capacitance C1, the low-voltage arm capacitance C2, the sampling resistor R1 and the sampling capacitor C; obtaining the output voltage U2 of the resistor-capacitor voltage divider type electronic transformer based on the input voltage U, the equivalent capacitance C3 and the sampling resistor R1; obtaining the voltage U3 based on the output voltage U2.

[0021] After the pole-mounted circuit breaker is added with a RC voltage-dividing electronic transformer, the voltage dividing ratio of the voltage transformer and the RC voltage-dividing electronic transformer changes. In order to accurately obtain the voltage U4 of the secondary output waveform, this system takes into account the structural composition of the voltage transformer and the RC voltage-dividing electronic transformer, and uses the first formula and the second formula to respectively calculate the output voltage U1 of the voltage transformer and the output voltage U2 of the RC voltage-dividing electronic transformer.

[0022] Furthermore, the system calculates the output voltage U1 of the voltage transformer based on a first formula, and the first formula is:

[0023]

[0024] Among them, U1 represents the output voltage of the voltage transformer, U represents the input voltage of the distribution line, C1 and C2 respectively represent the high-voltage arm capacitance and the low-voltage arm capacitance of the voltage transformer, R represents the resistance of the sampling resistor R1, C represents the sampling capacitor, j represents an imaginary number, and ω represents the angular velocity.

[0025] The system calculates the output voltage U2 of the RC voltage divider type electronic transformer based on the second formula, and the second formula is:

[0026]

[0027] Wherein, U2 represents the output voltage of the RC voltage divider type electronic transformer, C3 represents the equivalent capacitor C3, and dU / dt represents the differential of the input voltage U with respect to time t.

[0028] Furthermore, the specific steps of processing the high-frequency traveling wave signal based on the signal processing component to obtain a secondary output waveform of the high-frequency traveling wave signal include: the RC voltage divider type electronic transformer outputs the high-frequency traveling wave signal to the filtering circuit, the filtering circuit filters out the noise peaks of the high-frequency traveling wave signal to obtain a first waveform, the filtering circuit outputs the first waveform to the amplifying circuit, the amplifying circuit amplifies the first waveform to obtain a second waveform, the amplifying circuit outputs the second waveform to the multi-channel differential amplifying circuit, the multi-channel differential amplifying circuit processes the second waveform to obtain a third waveform, the multi-channel differential amplifying circuit outputs the third waveform to the sampling chip, and the sampling chip collects the third waveform to obtain the secondary output waveform.

[0029] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0030] 1. The built-in signal acquisition component of the pole-mounted circuit breaker is used to collect high-frequency traveling wave signals and the secondary-side induced electromotive force output waveform corresponding to the primary current, realizing the function of the pole-mounted circuit breaker to collect high-frequency signals. At the same time, the signal acquisition component is built into the pole-mounted circuit breaker and combined with the pole-mounted circuit breaker to achieve integration and simple line access. No additional high-frequency traveling wave signal acquisition device is required, which reduces costs, and the signal acquisition component does not affect the function and accuracy of the pole-mounted circuit breaker itself. 2. Based on the signal processing component, the high-frequency traveling wave signal is processed to obtain the secondary output waveform. The secondary output waveform and the secondary-side induced electromotive force output waveform can accurately locate the fault point of the distribution line. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation on the embodiments of the present invention;

[0032] Figure 1 It is a schematic diagram of a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker in the present invention;

[0033] Figure 2 It is a structural comparison diagram before and after the installation of a RC voltage-dividing electronic transformer in a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker in the present invention, wherein C5 and C4 respectively represent the high-voltage arm capacitance and the low-voltage arm capacitance of the voltage sensor when the RC voltage-dividing electronic transformer is not installed;

[0034] Figure 3 It is a design structure diagram of a resistance-capacitance voltage divider board of a resistance-capacitance voltage divider type electronic transformer used in a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker in the present invention, wherein U is an input port; RV is an interface of a varistor; R1 is an interface of a sampling resistor R1, C is an interface of a sampling capacitor C, and E is an output interface;

[0035] Figure 4 It is a comparison diagram of the ratio of the pole-mounted circuit breaker before and after the installation of the resistance-capacitance voltage-dividing type electronic transformer in a high-frequency signal acquisition and processing system for the pole-mounted circuit breaker in the present invention;

[0036] Figure 5 It is a phase difference comparison diagram of the pole-mounted circuit breaker before and after the installation of the resistance-capacitance voltage-dividing type electronic transformer in a high-frequency signal acquisition and processing system for the pole-mounted circuit breaker in the present invention;

[0037] Figure 6 This is an example of the secondary output waveform of a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker in the present invention. Figure 1 ;

[0038] Figure 7 This is an example of the secondary output waveform of a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker in the present invention. Figure 2 ;

[0039] Figure 8 This is an example of the secondary induced electromotive force output waveform of a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker in the present invention. Figure 1 ;

[0040] Fig. 9 This is an example of the secondary induced electromotive force output waveform of a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker in the present invention. Figure 2 . DETAILED DESCRIPTION

[0041] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those within the scope of this description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0043] Embodiment 1

[0044] refer to Figure 1 , Figure 2 and Figure 3 This embodiment provides a high-frequency signal acquisition and processing system for a pole-mounted circuit breaker, the system comprising:

[0045] Voltage acquisition module: used to collect high-frequency traveling wave signals of distribution lines based on the signal acquisition components built into the pole-mounted circuit breaker;

[0046] Current acquisition module: used for acquiring a secondary-side induced electromotive force signal corresponding to the primary current based on the signal acquisition component, and obtaining a secondary-side induced electromotive force output waveform based on the secondary-side induced electromotive force signal;

[0047] Signal processing module: used to process the high-frequency traveling wave signal based on the signal processing component to obtain the secondary output waveform of the high-frequency traveling wave signal, and locate the fault point of the distribution line based on the secondary output waveform and the secondary side induced electromotive force output waveform.

[0048] The signal acquisition component includes a voltage transformer and a RC voltage divider type electronic transformer, the input end of the voltage transformer is connected to the incoming line side of the pole-mounted circuit breaker, the output end of the voltage transformer is connected to the outgoing line side of the pole-mounted circuit breaker, the voltage transformer includes a high-voltage arm capacitor C1 and a low-voltage arm capacitor C2, the positive electrode of the high-voltage arm capacitor C1 is connected to the input end of the voltage transformer, the negative electrode of the high-voltage arm capacitor C1 is connected to the positive electrode of the low-voltage arm capacitor C2, the negative electrode of the low-voltage arm capacitor C2 is connected to the input end of the RC voltage divider type electronic transformer, and the grounding end of the RC voltage divider type electronic transformer is grounded. The RC voltage divider type electronic transformer is used to collect the high-frequency traveling wave signal of the distribution line.

[0049] Among them, the RC voltage divider type electronic transformer includes a RC voltage divider plate, a varistor, a sampling capacitor C and a sampling resistor R1. The varistor, the sampling capacitor C and the sampling resistor R1 are connected in parallel. The input ends of the varistor, the sampling capacitor C and the sampling resistor R1 are all connected to the input end of the RC voltage divider plate, and the output ends of the varistor, the sampling capacitor C and the sampling resistor R1 are all connected to the output end of the RC voltage divider plate.

[0050] Embodiment 2

[0051] On the basis of the first embodiment, in this embodiment, the signal acquisition component further includes a current transformer and a sampling resistor R2, the input end of the current transformer is connected to the input end of the pole-mounted circuit breaker, the output end of the current transformer is connected to the output end of the pole-mounted circuit breaker, one end of the secondary side terminal of the current transformer is connected to one end of the sampling resistor R2, and the other end of the secondary side terminal of the current transformer is connected to the other end of the sampling resistor R2. The secondary side induced electromotive force signal corresponding to the primary current is obtained based on the sampling resistor R2.

[0052] Embodiment 3

[0053] refer to Figure 1 , Figure 2 and Figure 3 On the basis of the above embodiments, in this embodiment, the signal processing component includes a filtering circuit, an amplifying circuit, a multi-channel differential amplifying circuit and a sampling chip. The input end of the filtering circuit is connected to the output end of the RC voltage divider type electronic transformer, the output end of the filtering circuit is connected to the input end of the amplifying circuit, the output end of the amplifying circuit is connected to the input end of the multi-channel differential amplifying circuit, the output end of the multi-channel differential amplifying circuit is connected to the input end of the sampling chip, and the output end of the sampling chip is used to connect to a waveform displayer.

[0054] In this embodiment, the filtering circuit may be a second-order LC filtering circuit, a high-pass filtering circuit or an RC high-pass filtering circuit; the amplifying circuit may be a single-ended amplifying circuit constructed with a high-speed operational amplifier as a basic element, or a single-ended amplifying circuit constructed with a low-power operational amplifier as a basic element; the multi-channel differential amplifying circuit may be a single-ended differential amplifying circuit constructed with a single-ended to differential amplifier as a basic element, or a differential amplifying circuit constructed with a high-speed differential amplifier as a basic element; the sampling chip may be a high-speed AD sampling chip or a high-speed ADC sampling chip; in this embodiment, preferably, the input end of the filtering circuit is connected to the output end of the RC voltage divider type electronic transformer through a coaxial cable, and the coaxial cable can reduce interference during the transmission of the high-frequency traveling wave signal and transmit the high-frequency traveling wave signal stably.

[0055] Among them, the specific steps of processing the high-frequency traveling wave signal based on the signal processing component to obtain the secondary output waveform of the high-frequency traveling wave signal include: the RC voltage divider type electronic transformer outputs the high-frequency traveling wave signal to the filtering circuit, the filtering circuit filters out the noise peaks of the high-frequency traveling wave signal to obtain a first waveform, the filtering circuit outputs the first waveform to the amplifying circuit, the amplifying circuit amplifies the first waveform to obtain a second waveform, the amplifying circuit outputs the second waveform to the multi-channel differential amplifying circuit, the multi-channel differential amplifying circuit processes the second waveform to obtain a third waveform, the multi-channel differential amplifying circuit outputs the third waveform to the sampling chip, and the sampling chip collects the third waveform to obtain the secondary output waveform.

[0056] Embodiment 4

[0057] refer to Figure 1 , Figure 2 , Figure 3 and Figure 6-Figure 9 On the basis of the above embodiments, in this embodiment, the RC voltage divider type electronic transformer collects the high-frequency traveling wave signal of the distribution line and outputs it to the filtering circuit, the filtering circuit filters out the high-frequency traveling wave signal to obtain a first waveform, the filtering circuit outputs the first waveform to the amplifying circuit, the amplifying circuit amplifies the first waveform to obtain a second waveform, the amplifying circuit outputs the second waveform to the multi-channel differential amplifying circuit, the multi-channel differential amplifying circuit processes the second waveform to obtain a third waveform, the multi-channel differential amplifying circuit outputs the third waveform to the sampling chip, and the sampling chip collects the third waveform to obtain the secondary output waveform.

[0058] At the same time, the current transformer collects the secondary induced electromotive force signal corresponding to the primary current on the sampling resistor R2, and obtains the secondary induced electromotive force output waveform based on the secondary induced electromotive force signal. The secondary output waveform and the secondary induced electromotive force output waveform can locate the fault point of the distribution line.

[0059] Embodiment 5

[0060] refer to Figure 1 , Figure 2 and Figure 3On the basis of the above embodiment, in this embodiment, the voltage acquisition module is further used to obtain the voltage U3 of the high-frequency traveling wave signal and the output voltage U1 of the voltage transformer based on the signal acquisition component; obtain the voltage U4 of the secondary output waveform based on the voltage U3, and the output voltage U1 and the voltage U4 are used to reflect the change of the secondary output waveform; the specific steps of obtaining the voltage U3 of the high-frequency traveling wave signal and the output voltage U1 of the voltage transformer based on the signal acquisition component include: obtaining the input voltage U of the distribution line through a voltmeter; obtaining the equivalent capacitance C3 of the RC voltage divider type electronic transformer based on the high-voltage arm capacitance C1 and the low-voltage arm capacitance C2; ​​obtaining the output voltage U1 based on the input voltage U, the high-voltage arm capacitance C1, the low-voltage arm capacitance C2, the sampling resistor R1 and the sampling capacitor C; obtaining the output voltage U2 of the RC voltage divider type electronic transformer based on the input voltage U, the equivalent capacitance C3 and the sampling resistor R1; obtaining the voltage U3 based on the output voltage U2.

[0061] The system calculates the output voltage U1 of the voltage transformer based on the first formula, and the first formula is:

[0062]

[0063] Among them, U1 represents the output voltage of the voltage transformer, U represents the input voltage of the distribution line, C1 and C2 respectively represent the high-voltage arm capacitance and the low-voltage arm capacitance of the voltage transformer, R represents the resistance of the sampling resistor R1, C represents the sampling capacitor, j represents an imaginary number, and ω represents the angular velocity.

[0064] The system calculates the output voltage U2 of the RC voltage divider type electronic transformer based on the second formula, and the second formula is:

[0065]

[0066] Wherein, U2 represents the output voltage of the RC voltage divider type electronic transformer, C3 represents the equivalent capacitor C3, and dU / dt represents the differential of the input voltage U with respect to time t.

[0067] Among them, the condition of the second formula is

[0068]

[0069] Embodiment 6

[0070] refer to Figure 2 and Figure 4-Figure 9On the basis of the above-mentioned embodiments, this embodiment illustrates that after the pole-mounted circuit breaker is installed with a resistor-capacitor voltage-dividing electronic transformer, the function and accuracy of the pole-mounted circuit breaker itself are not affected.

[0071] refer to Figure 2 Before the pole-mounted circuit breaker is installed with a RC voltage-dividing electronic transformer, the output voltage U1 of the voltage transformer is:

[0072] in,

[0073] After the pole-mounted circuit breaker is installed with a RC voltage-dividing electronic transformer, the output voltage U1 of the voltage transformer is:

[0074] in,

[0075] Assuming that the transformation ratio coefficient of the output voltage U1 of the voltage transformer is a=K2 / K1, then:

[0076]

[0077] Since the voltage transformer is modified by using the RC voltage divider type electronic transformer, the capacitance values ​​of C1 and C5 are equal, and the capacitance values ​​of C2 and C4 are equal, which are essentially the same capacitor. Therefore, it can be seen from the formula that the change range of the transformation ratio change coefficient a mainly depends on the change of the complex imaginary part related to the numerator and denominator, that is, the difference between the numerator and denominator of the calculation formula is mainly in the numerical change of the sampling capacitor C, that is, the change of C in the formula. Under the premise of ensuring the stability of the parameters of the sampling resistor R1, the change range of the output voltage U1 of the voltage transformer at this time mainly depends on the comparison degree of the numerical values ​​of the sampling capacitor C and the high-voltage arm capacitor C1 and the low-voltage arm capacitor C2 of the voltage transformer, but in actual applications, the order of magnitude of the sampling capacitor C is 10 -6 , i.e. uF level, while the order of magnitude of the high voltage arm capacitance C1 and the low voltage arm capacitance C2 of the voltage transformer is 10 -9 , i.e. nF level, which results in that in the calculation of the transformation ratio variation coefficient a, the imaginary parts of the numerator and the denominator actually change relatively little, so the ratio difference and phase difference of the voltage transformer signal itself change slightly. Also, due to the influence of environmental factors in the actual accuracy test, the gap is small and almost negligible.

[0078] In the experimental test, the accuracy of the pole-mounted circuit breaker is tested by using waveform display equipment such as an oscilloscope, and the waveform output is directly performed, such as Figure 4 and Figure 5 .

[0079] From the above, it can be concluded that the influence of the RC voltage-dividing electronic transformer on the accuracy and phase difference of the voltage transformer of the pole-mounted circuit breaker is very small and can be basically ignored, meeting the accuracy requirements.

[0080] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0081] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A high-frequency signal acquisition and processing system for a pole-mounted circuit breaker, characterized in that: The system comprises: Voltage acquisition module: used to collect high-frequency traveling wave signals of distribution lines based on the signal acquisition components built into the pole-mounted circuit breaker; Current acquisition module: used for acquiring a secondary-side induced electromotive force signal corresponding to the primary current based on the signal acquisition component, and obtaining a secondary-side induced electromotive force output waveform based on the secondary-side induced electromotive force signal; Signal processing module: used for obtaining a secondary output waveform of the high-frequency traveling wave signal by processing the high-frequency traveling wave signal based on the signal processing component, and locating the fault point of the distribution line based on the secondary output waveform and the secondary-side induced electromotive force output waveform; The signal acquisition component includes a voltage transformer and a RC voltage divider type electronic transformer, the input end of the voltage transformer is connected to the incoming line side of the pole-mounted circuit breaker, the output end of the voltage transformer is connected to the outgoing line side of the pole-mounted circuit breaker, the voltage transformer includes a high-voltage arm capacitor C1 and a low-voltage arm capacitor C2, the positive electrode of the high-voltage arm capacitor C1 is connected to the input end of the voltage transformer, the negative electrode of the high-voltage arm capacitor C1 is connected to the positive electrode of the low-voltage arm capacitor C2, the negative electrode of the low-voltage arm capacitor C2 is connected to the input end of the RC voltage divider type electronic transformer, and the grounding end of the RC voltage divider type electronic transformer is grounded; The RC voltage divider type electronic transformer comprises a RC voltage divider plate, a varistor, a sampling capacitor C and a sampling resistor R1, wherein the varistor, the sampling capacitor C and the sampling resistor R1 are connected in parallel, and the input ends of the varistor, the sampling capacitor C and the sampling resistor R1 are all connected to the input end of the RC voltage divider plate, and the output ends of the varistor, the sampling capacitor C and the sampling resistor R1 are all connected to the output end of the RC voltage divider plate; The signal acquisition component also includes a current transformer and a sampling resistor R2, the input end of the current transformer is connected to the input end of the pole-mounted circuit breaker, the output end of the current transformer is connected to the output end of the pole-mounted circuit breaker, one end of the secondary side terminal of the current transformer is connected to one end of the sampling resistor R2, and the other end of the secondary side terminal of the current transformer is connected to the other end of the sampling resistor R2; The RC voltage-dividing electronic transformer is used to collect the high-frequency traveling wave signal of the power distribution line; Obtaining the secondary-side induced electromotive force signal corresponding to the primary current based on the sampling resistor R2; The sampling capacitor C is in the order of uF, and the high-voltage arm capacitor C1 and the low-voltage arm capacitor C2 of the voltage transformer are in the order of nF, so the ratio difference and phase difference of the signal of the voltage transformer change slightly, and the influence of the RC voltage divider type electronic transformer on the accuracy and phase difference of the voltage transformer is very small.

2. A high-frequency signal acquisition and processing system for a pole-mounted circuit breaker according to claim 1, characterized in that: The signal processing component includes a filtering circuit, an amplifying circuit, a multi-channel differential amplifying circuit and a sampling chip. The input end of the filtering circuit is connected to the output end of the RC voltage divider type electronic transformer, the output end of the filtering circuit is connected to the input end of the amplifying circuit, the output end of the amplifying circuit is connected to the input end of the multi-channel differential amplifying circuit, the output end of the multi-channel differential amplifying circuit is connected to the input end of the sampling chip, and the output end of the sampling chip is used to connect to a waveform displayer.

3. A high-frequency signal acquisition and processing system for a pole-mounted circuit breaker according to claim 1, characterized in that: The voltage acquisition module is also used to obtain the voltage U3 of the high-frequency traveling wave signal and the output voltage U1 of the voltage transformer based on the signal acquisition component; Based on the voltage U3, the voltage U4 of the secondary output waveform is obtained, and the output voltage U1 and the voltage U4 are used to reflect the change of the secondary output waveform; The specific steps of obtaining the voltage U3 of the high-frequency traveling wave signal and the output voltage U1 of the voltage transformer based on the signal acquisition component include: obtaining the input voltage U of the distribution line; obtaining the equivalent capacitance C3 of the RC voltage divider type electronic transformer based on the high-voltage arm capacitance C1 and the low-voltage arm capacitance C2; ​​obtaining the output voltage U1 based on the input voltage U, the high-voltage arm capacitance C1, the low-voltage arm capacitance C2, the sampling resistor R1 and the sampling capacitor C; obtaining the output voltage U2 of the RC voltage divider type electronic transformer based on the input voltage U, the equivalent capacitance C3 and the sampling resistor R1; and obtaining the voltage U3 based on the output voltage U2.

4. A high-frequency signal acquisition and processing system for a pole-mounted circuit breaker according to claim 3, characterized in that: The system calculates the output voltage U1 of the voltage transformer based on the first formula, and the first formula is: Wherein, U1 represents the output voltage of the voltage transformer, U represents the input voltage U of the distribution line, C1 and C2 represent the high-voltage arm capacitance C1 and the low-voltage arm capacitance C2 of the voltage transformer respectively, R represents the resistance of the sampling resistor R1, C represents the sampling capacitor C, j represents an imaginary number, and ω represents an angular velocity; The system calculates the output voltage U2 of the RC voltage divider type electronic transformer based on the second formula, and the second formula is: Wherein, U2 represents the output voltage of the RC voltage divider type electronic transformer, C3 represents the equivalent capacitor C3, and dU / dt represents the differential of the input voltage U of the distribution line with respect to time t.

5. A high-frequency signal acquisition and processing system for a pole-mounted circuit breaker according to claim 2, characterized in that: The specific steps of processing the high-frequency traveling wave signal based on the signal processing component to obtain the secondary output waveform of the high-frequency traveling wave signal include: the RC voltage divider type electronic transformer outputs the high-frequency traveling wave signal to the filtering circuit, the filtering circuit filters out the noise peaks of the high-frequency traveling wave signal to obtain a first waveform, the filtering circuit outputs the first waveform to the amplifying circuit, the amplifying circuit amplifies the first waveform to obtain a second waveform, the amplifying circuit outputs the second waveform to the multi-channel differential amplifying circuit, the multi-channel differential amplifying circuit processes the second waveform to obtain a third waveform, the multi-channel differential amplifying circuit outputs the third waveform to the sampling chip, and the sampling chip collects the third waveform to obtain the secondary output waveform.

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