Jet type fuse breaking time detection device and use method thereof

Abstract

The invention provides an injection fuse on-off time detection device and a use method thereof. The detection device comprises an upper computer, an injection fuse, an adjustable resistor, an MMC converter, a first switch, a second switch, an ammeter and a voltmeter, wherein the adjustable resistor, the MMC converter, the first switch, the second switch, the ammeter and the voltmeter are electrically connected with the upper computer; the jet fuse, the adjustable resistor, the ampere meter and the MMC converter are sequentially connected in series; one end of the second switch is electrically connected with one end, far away from the ammeter, of the adjustable resistor, and the other end of the second switch is electrically connected with one end, far away from the MMC converter, of the jet fuse; one end of the first switch is electrically connected with one end of the adjustable resistor away from the ammeter, and the other end is electrically connected with one end of the adjustable resistor away from the second switch; two ends of the voltmeter are electrically connected with two ends of the first switch respectively. According to the invention, the stable operation of the jet fuse under different load conditions is ensured, the compactness and reliability of the detection device are improved, and the complexity of external connection is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of distribution network control and protection, and in particular relates to a device for detecting the breaking time of a jet fuse. Background Art

[0002] As a key protection device in the distribution network, the breaking time of the ejector fuse is directly related to the protection performance and power supply reliability of the distribution network. Quickly and accurately detecting the breaking time of the fuse can not only evaluate whether its performance meets the technical requirements, but also ensure that the fault current is cut off in time in practical applications, reducing the impact of the fault on the distribution system and its equipment. In addition, the precise test of the breaking time provides important data support for the research and development and performance improvement of new fuses, which is of great significance for improving the stability and safety of power grid operation.

[0003] At present, the breaking time detection of ejector fuses usually adopts two methods: laboratory simulation and field measurement. Among them, laboratory detection simulates the short-circuit fault condition in the distribution network by applying high voltage and high current, and records the response time of the fuse in combination with voltage and current sensors; field measurement relies on the actual fault events that occur in the operation of the distribution network for testing. These detection methods usually require large-capacity high-voltage and large short-circuit current generation equipment to meet the testing requirements of real working conditions.

[0004] Existing detection methods rely on strong voltage sources and short-circuit capacity support in the power system, which leads to high construction costs of test equipment and large system footprint. In addition, the complexity of large-capacity test systems makes it difficult to ensure the accuracy of their output voltage waveforms, affecting the accuracy of the test results. At the same time, these methods have limited flexibility in simulating load conditions and are difficult to meet the needs of comprehensive evaluation of fuse performance in different working scenarios. Therefore, the existing technology urgently needs a compact, efficient, low-cost, high-precision detection device that can flexibly simulate a variety of working conditions to overcome the shortcomings of traditional detection technology. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a device for detecting the breaking time of an ejection type fuse and a method for using the device.

[0006] In a first aspect, the present invention provides a device for detecting the breaking time of an ejection type fuse, comprising a host computer, an ejection type fuse, and an adjustable resistor electrically connected to the host computer, an MMC converter, a first switch, a second switch, an ammeter, and a voltmeter;

[0007] The ejection fuse, adjustable resistor, ammeter and MMC converter are connected in series in sequence; one end of the second switch is electrically connected to an end of the adjustable resistor away from the ammeter, and the other end of the second switch is electrically connected to an end of the ejection fuse away from the MMC converter; one end of the first switch is electrically connected to an end of the adjustable resistor away from the ammeter, and the other end of the first switch is electrically connected to an end of the adjustable resistor away from the second switch; and the two ends of the voltmeter are electrically connected to the two ends of the first switch respectively.

[0008] Optionally, the first aspect further includes a filter; the filter includes an adjustable inductor and a first capacitor; one end of the adjustable inductor is electrically connected to an end of the ammeter away from the adjustable resistor, and the other end is electrically connected to an end of the MMC converter away from the ejection fuse;

[0009] One end of the first capacitor is electrically connected to an end of the ammeter away from the adjustable resistor, and the other end of the first capacitor is electrically connected to an end of the ejection fuse away from the second switch.

[0010] Optionally, the MMC converter includes a plurality of submodules connected in series; each of the submodules includes a first insulated gate bipolar transistor, a second insulated gate bipolar transistor, a first diode, a second diode, a second capacitor and a battery;

[0011] Two ends of the second capacitor are electrically connected to the positive electrode and the negative electrode of the battery respectively;

[0012] The collector of the first insulated gate bipolar transistor is electrically connected to the positive electrode of the battery, and the emitter is electrically connected to the collector of the second insulated gate bipolar transistor;

[0013] The emitter of the second insulated gate bipolar transistor is electrically connected to the negative electrode of the battery;

[0014] The anode of the first diode is electrically connected to the emitter of the first insulated gate bipolar transistor, and the cathode of the first diode is electrically connected to the collector of the first insulated gate bipolar transistor;

[0015] The anode of the second diode is electrically connected to the emitter of the second insulated gate bipolar transistor, and the cathode of the second diode is electrically connected to the collector of the second insulated gate bipolar transistor;

[0016] The input end of each of the submodules is electrically connected to the collector of the second insulated gate bipolar transistor; and the output end of each of the submodules is electrically connected to the emitter of the second insulated gate bipolar transistor.

[0017] Optionally, the resistance range of the adjustable resistor is 0Ω to 2000Ω.

[0018] Optionally, the inductance range of the adjustable inductor is 0.1 mH to 10 mH.

[0019] Optionally, the first switch and the second switch are both high-voltage fast-transfer switches.

[0020] Optionally, the MMC converter adopts phase-shift modulation and closed-loop control to output 10kV AC voltage to simulate the operating conditions of the distribution network.

[0021] In a second aspect, the present invention provides a method for using the ejection type fuse breaking time detection device as described in the first aspect, comprising:

[0022] S1, set the resistance value of the adjustable resistor;

[0023] S2, modulating the signal of the MMC converter to generate a preset target voltage;

[0024] S3, controlling the first switch to close so that the current passes through the adjustable resistor, and when the acquired current value meets the preset target current, controlling the first switch to open;

[0025] S4, controlling the second switch to close to apply the target voltage to the ejection fuse;

[0026] S5, after the target voltage is applied to the ejection type fuse, obtaining a waveform of the current of the ejection type fuse as a first waveform;

[0027] S6, extracting the transient characteristics of the first waveform to determine the time from when the second switch is closed to when the current of the ejection fuse drops to zero, and use the time as the ejection fuse breaking time.

[0028] Optionally, the second aspect further includes repeatedly executing S1-S6 to a target number of times to obtain a target number of ejection fuse breaking times, and taking an average value of the target number of ejection fuse breaking times as the final ejection fuse breaking time.

[0029] The present invention provides a device for detecting the breaking time of a jet fuse and a method for using the device. The MMC converter in the device outputs 10kV AC power by using phase-shift modulation and closed-loop control methods. This control strategy improves the accuracy of voltage control and the quality of electric energy, and ensures the stable operation of the jet fuse under different load conditions. The jet fuse, the MMC converter and the host computer are integrated into one, which improves the compactness and reliability of the detection device and reduces the complexity of external connections. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the structure of a device for detecting the breaking time of an ejection type fuse provided by an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the structure of the submodules provided in an embodiment of the present invention;

[0033] Figure 3 The present invention provides a flowchart of a method for using the ejection fuse breaking time detection device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figure 1 As shown, this embodiment provides a device for detecting the breaking time of an ejection type fuse, including an upper computer UC, an ejection type fuse F, an adjustable resistor R electrically connected to the upper computer UC, an MMC converter SM, a first switch S1, a second switch S2, an ammeter A and a voltmeter V.

[0037] The ejection fuse F, the adjustable resistor R, the ammeter A and the MMC converter SM are connected in series in sequence; one end of the second switch S2 is electrically connected to the end of the adjustable resistor R away from the ammeter A, and the other end of the second switch S2 is electrically connected to the end of the ejection fuse F away from the MMC converter SM; one end of the first switch S1 is electrically connected to the end of the adjustable resistor R away from the ammeter A, and the other end of the first switch S1 is electrically connected to the end of the adjustable resistor R away from the second switch S2; the two ends of the voltmeter V are electrically connected to the two ends of the first switch S1 respectively.

[0038] In this embodiment, the first switch S1 and the second switch S2 are both high-voltage fast-transfer switches to meet the circuit breaking condition. Of course, the first switch S1 and the second switch S2 can also be circuit breakers with switching functions.

[0039] The adjustable resistor has a resistance range of 0Ω to 2000Ω. The MMC converter SM uses phase-shift modulation and closed-loop control to output 10kV AC voltage to simulate the operating conditions of the distribution network.

[0040] The MMC converter SM comprises a plurality of submodules connected in series; Figure 2 As shown, each submodule SM i The invention comprises a first insulated gate bipolar transistor T1, a second insulated gate bipolar transistor T2, a first diode D1, a second diode D2, a second capacitor C2 and a battery B.

[0041] The two ends of the second capacitor C2 are electrically connected to the positive electrode and the negative electrode of the battery B. The second capacitor C2 and the battery B jointly provide electric energy for the MMC converter SM to ensure stable operation under different working conditions. The second capacitor C2 is connected to the input end of the MMC converter SM through the DC bus to provide electric energy for it to ensure stable operation under high load conditions.

[0042] The collector of the first insulated gate bipolar transistor T1 is electrically connected to the positive electrode of the battery B, and the emitter (of T1 ) is electrically connected to the collector of the second insulated gate bipolar transistor T2 .

[0043] The emitter of the second insulated gate bipolar transistor T2 is electrically connected to the negative electrode of the battery B.

[0044] An anode of the first diode D1 is electrically connected to the emitter of the first insulated gate bipolar transistor T1 , and a cathode of the first diode D1 is electrically connected to the collector of the first insulated gate bipolar transistor T1 .

[0045] An anode of the second diode D2 is electrically connected to the emitter of the second insulated gate bipolar transistor T2 , and a cathode of the second diode D2 is electrically connected to the collector of the second insulated gate bipolar transistor.

[0046] Each submodule SM i The input terminal of the submodule SM is electrically connected i The collector of the second internal insulated gate bipolar transistor T2; each submodule SM i The output terminal is electrically connected to the submodule SM i The emitter of the internal second insulated gate bipolar transistor T2.

[0047] Assume that the MMC converter SM has ten submodules, that is, i = 1, 2, ..., 10. The ten submodules are connected in series in sequence. If the output end of the first submodule SM1 is electrically connected to the end of the ammeter A away from the adjustable resistor R, then the tenth submodule SM 10 The input end is electrically connected to an end of the ejection fuse F away from the second switch S2.

[0048] Exemplarily, the ejection fuse breaking time detection device provided in this embodiment further includes a low-pass filter for filtering out high-frequency harmonics in the output voltage of the MMC converter SM to ensure the stability and purity of the output voltage. The filter includes an adjustable inductor L and a first capacitor C1; one end of the adjustable inductor L is electrically connected to an end of the ammeter A away from the adjustable resistor R, and the other end of the adjustable inductor L is electrically connected to an end of the MMC converter SM away from the ejection fuse F.

[0049] One end of the first capacitor C1 is electrically connected to one end of the ammeter A away from the adjustable resistor R, and the other end of the first capacitor C1 is electrically connected to one end of the ejection fuse F away from the second switch S2.

[0050] In this embodiment, the inductance range of the adjustable inductor L is 0.1 mH to 10 mH.

[0051] Assume that the MMC converter SM has ten submodules, that is, i = 1, 2, ..., 10. The ten submodules are connected in series in sequence. If one end of the adjustable inductor L is electrically connected to the output end of the first submodule SM1, then the tenth submodule SM 10 The input end of the first capacitor C1 is electrically connected to one end of the first capacitor C1. At this time, the first capacitor C1 is far away from the tenth submodule SM 10 One end of the adjustable inductor L is electrically connected to an end of the adjustable inductor L away from the first sub-module SM1.

[0052] In the jet fuse breaking time detection device provided in this embodiment, the host computer UC sets the resistance value of the adjustable resistor R to simulate different current conditions; the host computer UC modulates the signal of the MMC converter SM to generate a preset target voltage; the host computer UC controls the first switch S1 to close so that the current passes through the adjustable resistor R, and when the acquired current value meets the preset target current, the host computer UC controls the first switch S1 to open; the host computer UC controls the second switch S2 to close so as to apply the target voltage to the jet fuse F; after the target voltage is applied to the jet fuse, the waveform of the current of the jet fuse is obtained; the host computer UC extracts the transient characteristics of the waveform of the current of the jet fuse F to determine the time from the closing of the second switch S2 to the current of the jet fuse F dropping to zero, and uses it as the breaking time of the jet fuse F.

[0053] Among them, the design of adjustable resistor R can simulate different current load conditions, increase the flexibility and coverage of the test, and can more comprehensively evaluate the performance of the ejector fuse F; the MMC converter SM uses phase-shift modulation and closed-loop control methods to output 10kV AC. This control strategy improves the accuracy of voltage control and power quality, ensuring the stable operation of the ejector fuse F under different load conditions. The ejector fuse F, MMC converter SM and host computer UC are integrated into one, which improves the compactness and reliability of the detection device and reduces the complexity of external connections.

[0054] Example 2

[0055] Corresponding to the device for detecting the breaking time of an ejection type fuse provided in Example 1, this embodiment provides a method for using the device for detecting the breaking time of an ejection type fuse.

[0056] like Figure 3 As shown, the method for using the ejection type fuse breaking time detection device includes:

[0057] S1, sets the resistance value of the adjustable resistor.

[0058] S2, modulates the signal of the MMC converter to generate a preset target voltage.

[0059] S3, controlling the first switch to close so that current passes through the adjustable resistor, and when the acquired current value meets the preset target current, controlling the first switch to open.

[0060] S4, controlling the second switch to close to apply the target voltage to the ejection fuse.

[0061] S5, after the target voltage is applied to the ejection type fuse, a waveform of the current of the ejection type fuse is obtained as a first waveform.

[0062] S6, extracting the transient characteristics of the first waveform to determine the time from when the second switch is closed to when the current of the ejection fuse drops to zero, and use the time as the ejection fuse breaking time.

[0063] Exemplarily, this embodiment further includes repeatedly executing S1-S6 to a target number of times to obtain a target number of ejection fuse breaking times, and taking an average value of the target number of ejection fuse breaking times as the final ejection fuse breaking time.

[0064] In this embodiment, the low-pass filtering process uses a finite impulse response (FIR) low-pass filter to remove high-frequency noise and retain the main frequency components of the signal, so that the subsequent Hilbert transform is more accurate. The discrete filtering formula is as follows:

[0065]

[0066] Among them, i f [n] represents the filtered signal; i[n] represents the input original current signal; h[k] represents the filter coefficient of the low-pass filter, which is determined by the window function method; M is the order of the low-pass filter; n is the time domain index number of the sampling point; k is the filter coefficient index number.

[0067] Hilbert transform is used to extract the envelope and instantaneous change characteristics of the current signal, the discrete Fourier transform (DFT) of the signal, and the discrete Fourier transform formula is as follows:

[0068]

[0069] Among them, I[k1] represents the frequency domain signal; N is the length of the frequency domain signal; k1 is the frequency component index number, and e is a natural constant.

[0070] Spectrum correction: Hilbert transform is implemented in the frequency domain by constructing an analytical signal and adjusting the frequency domain components as follows:

[0071]

[0072] H[k] represents the intermediate variable of spectrum correction.

[0073] Inverse Fourier transform: Inversely transform the corrected spectrum to obtain the signal after Hilbert transform:

[0074]

[0075] is the signal after Hill wave head transformation.

[0076] Extract the signal amplitude envelope a[n] and zero point detection based on Hilport transform:

[0077] (1) Amplitude envelope

[0078]

[0079] (2) Zero point detection

[0080] In the signal a[n], when the detection drops from non-zero to zero (or less than the set threshold), the time t1 is recorded. According to the second switch closing time t0 recorded by the host computer, the breaking time t break =t1-t0.

[0081] In summary, this embodiment provides a method for using a jet fuse breaking time detection device, which uses low-pass filtering and Hilbert transform to extract the transient characteristics of the current waveform, accurately identifies the moment when the second switch is closed and the moment when the jet fuse current drops to zero, and accurately calculates the breaking time of the jet fuse, thereby improving the accuracy and efficiency of the measurement, reducing human errors, and thereby improving the reliability and safety of the distribution network operation.

[0082] The embodiments in this specification are described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the device embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the device embodiment. The device embodiment described above is only schematic, wherein the unit described as a separate component may or may not be physically separated, and the component displayed as a unit may or may not be a physical unit, that is, it may be located in one place, or it may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0083] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity from another entity, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising" is intended to cover non-exclusive inclusion, so that a system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a system. In the absence of further restrictions, the elements defined by the sentence "comprising..." do not exclude the existence of other identical elements in the system including the elements.

[0084] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A device for detecting the breaking time of an ejection type fuse, characterized in that: It includes a host computer, an ejection fuse, an adjustable resistor electrically connected to the host computer, an MMC converter, a first switch, a second switch, an ammeter and a voltmeter; The ejection fuse, adjustable resistor, ammeter and MMC converter are connected in series in sequence; one end of the second switch is electrically connected to an end of the adjustable resistor away from the ammeter, and the other end of the second switch is electrically connected to an end of the ejection fuse away from the MMC converter; one end of the first switch is electrically connected to an end of the adjustable resistor away from the ammeter, and the other end of the first switch is electrically connected to an end of the adjustable resistor away from the second switch; and the two ends of the voltmeter are electrically connected to the two ends of the first switch respectively.

2. The ejection fuse breaking time detection device according to claim 1, characterized in that: It also includes a filter; the filter includes an adjustable inductor and a first capacitor; one end of the adjustable inductor is electrically connected to an end of the ammeter away from the adjustable resistor, and the other end is electrically connected to an end of the MMC converter away from the ejection fuse; One end of the first capacitor is electrically connected to an end of the ammeter away from the adjustable resistor, and the other end of the first capacitor is electrically connected to an end of the ejection fuse away from the second switch.

3. The ejection type fuse breaking time detection device according to claim 1, characterized in that: The MMC converter comprises a plurality of submodules connected in series; each of the submodules comprises a first insulated gate bipolar transistor, a second insulated gate bipolar transistor, a first diode, a second diode, a second capacitor and a battery; Two ends of the second capacitor are electrically connected to the positive electrode and the negative electrode of the battery respectively; The collector of the first insulated gate bipolar transistor is electrically connected to the positive electrode of the battery, and the emitter is electrically connected to the collector of the second insulated gate bipolar transistor; The emitter of the second insulated gate bipolar transistor is electrically connected to the negative electrode of the battery; The anode of the first diode is electrically connected to the emitter of the first insulated gate bipolar transistor, and the cathode of the first diode is electrically connected to the collector of the first insulated gate bipolar transistor; The anode of the second diode is electrically connected to the emitter of the second insulated gate bipolar transistor, and the cathode of the second diode is electrically connected to the collector of the second insulated gate bipolar transistor; The input end of each of the submodules is electrically connected to the collector of the second insulated gate bipolar transistor; and the output end of each of the submodules is electrically connected to the emitter of the second insulated gate bipolar transistor.

4. The ejection fuse breaking time detection device according to claim 1, characterized in that: The resistance range of the adjustable resistor is 0Ω to 2000Ω.

5. The ejection type fuse breaking time detection device according to claim 2, characterized in that: The inductance range of the adjustable inductor is 0.1 mH to 10 mH.

6. The device for detecting the breaking time of an ejection type fuse according to claim 1, characterized in that: The first switch and the second switch are both high-voltage fast-transfer switches.

7. The ejection fuse breaking time detection device according to claim 1, characterized in that: The MMC converter adopts phase-shift modulation and closed-loop control to output 10 kV AC voltage to simulate the operating conditions of the distribution network.

8. A method for using the ejection fuse breaking time detection device according to any one of claims 1 to 7, characterized in that: include: S1, set the resistance value of the adjustable resistor; S2, modulating the signal of the MMC converter to generate a preset target voltage; S3, controlling the first switch to close so that the current passes through the adjustable resistor, and when the acquired current value meets the preset target current, controlling the first switch to open; S4, controlling the second switch to close to apply the target voltage to the ejection fuse; S5, after the target voltage is applied to the ejection type fuse, obtaining a waveform of the current of the ejection type fuse as a first waveform; S6, extracting the transient characteristics of the first waveform to determine the time from when the second switch is closed to when the current of the ejection fuse drops to zero, and use the time as the ejection fuse breaking time.

9. The method of use according to claim 8, characterized in that: S1-S6 are repeatedly executed to the target number of times to obtain the target number of jet fuse breaking times, and the average value of the target number of jet fuse breaking times is used as the final jet fuse breaking time.

Images