Arc suppression coil capacitive flow on-line measurement method

Abstract

The invention relates to the technical field of power distribution network measurement, and particularly discloses an arc suppression coil capacitive current on-line measurement method, which comprises the steps of injecting three kinds of measurement currents i1, i2 and i3 with different frequencies into a secondary side of a voltage transformer, collecting the frequencies, amplitudes and phases of the injected currents i1, i2 and i3, and the voltage amplitude and phase of the secondary side of the voltage transformer, and calculating the amplitudes M1, M2 and M3 and the phases p1, p2 and p3 of the impedances Z1, Z2 and Z3 corresponding to the equivalent model under the three injection currents, and calculating the value of the ground capacitance C of the power distribution network according to the obtained equivalent impedance of the measurement circuit. The method has the capability of accurately monitoring the capacitive current of the arc suppression coil of the power distribution network on line when the parameters of the arc suppression coil are uncertain, and a theoretical basis and technical support are provided for ensuring the safe and stable operation of the power distribution network.

Description

Technical Field

[0001] The present application relates to the technical field of distribution network measurement, and in particular to an online measurement method for the capacitance and current of an arc suppression coil. Background Art

[0002] With the continuous development of my country's urban power system and the continuous increase of high-voltage electrical equipment and cable lines in the distribution network, the level of zero-sequence capacitive current has become a key factor affecting the safety, equipment maintenance, system scheduling and development planning of the distribution network. A key factor in ensuring the safe operation of the distribution network is to accurately measure the capacitive current, but the current measurement technology has problems such as insufficient data collection, inability to fully monitor the changes in capacitive current, and lack of real-time online monitoring capabilities. In addition, with the widespread application of new equipment such as integrated switches, the grounding points of these devices themselves cause the grounding parameters of the distribution network to change continuously, making it difficult for existing offline measurement technologies to adapt to the needs of actual scenarios. Therefore, there is an urgent need to develop a arc suppression coil capacitance current measurement technology to ensure the safe and stable operation of the distribution network.

[0003] In the research of arc suppression coil capacitance and current measurement technology, researchers at home and abroad have conducted a series of explorations. One of the current technical solutions is the capacitance current measurement based on the three-frequency method. The implementation principle of this method is to use three different frequency currents injected by the secondary side of the voltage transformer to calculate the capacitance current, but its measurement range and accuracy are limited, and real-time monitoring cannot be achieved. Another technical solution is to inject variable frequency current into the distribution network, measure the corresponding voltage, and establish a variable frequency equivalent circuit model in combination with the damping resistor to deduce the capacitance current. Although this method improves the measurement accuracy, its measurement range is limited, and it is difficult to perform online measurement when the arc suppression coil parameters are unknown. Therefore, developing a new measurement technology to improve the measurement range and accuracy is crucial for real-time monitoring and safety management of the distribution network. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present application proposes an online measurement method for the current capacity of arc extinguishing coils, which can achieve accurate measurement of the current capacity of arc extinguishing coils and significantly improve the measurement range and accuracy.

[0005] In order to achieve the above object, the present application provides an online measurement method of arc suppression coil current, comprising: Step S1: Inject three different frequencies of measurement current into the secondary side of the voltage transformer i 1. i 2. i 3; Step S2: Collecting the injected current i 1. i 2. i Frequency of 3 oh 1. oh 2. oh 3. Amplitude I 1. I 2. I 3 and Phase f i1. f i2, f i3, and the voltage amplitude on the secondary side of the voltage transformer U 1. U 2. U 3 and phase f u1, f u2, f u3; Step S3: Calculate the impedance corresponding to the equivalent model under three injection currents Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p 3; Step S4: Calculate the value of the distribution network-to-ground capacitance C based on the acquired measurement circuit equivalent impedance.

[0006] In some possible implementations, the impedance corresponding to the equivalent model under the three injection currents is calculated. Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p 3. Includes: The impedance Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p The calculation expression of 3 is: , where , , They represent the phase of the secondary voltage of the voltage transformer at three different frequencies. , , Respectively represent the measured current phases of three different frequencies.

[0007] In some possible implementations, the calculating the value of the capacitance C of the distribution network to the ground according to the acquired equivalent impedance of the measurement circuit includes: The calculation expression of the distribution network to ground capacitance C is: .

[0008] In some possible implementations, the injecting of three different frequencies of measurement current into the secondary side of the voltage transformer i 1. i 2. i 3. It also includes: constructing a distribution network capacitance and current test circuit model.

[0009] Compared with the prior art, the technical solution provided by the embodiment of the present application includes at least the following beneficial effects or advantages: The online measurement technology of arc suppression coil capacitance and current proposed in this application has the ability to accurately monitor the arc suppression coil capacitance and current of the distribution network online even when the arc suppression coil parameters are uncertain, providing a solid theoretical basis and technical support for ensuring the safe and stable operation of the distribution network.

[0010] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0012] Figure 1 It is a flow chart of an online method for measuring the capacitance of an arc suppression coil according to an embodiment of the present application. DETAILED DESCRIPTION

[0013] The embodiments of the present application are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0014] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific implementations and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0015] See also Figure 1 , Figure 1 A flow chart of an arc suppression coil current online measurement method is shown. This embodiment provides an arc suppression coil current online measurement method, including: Step S1: Inject three different frequencies of measurement current into the secondary side of the voltage transformer i 1. i 2. i 3; In this step, first, it is necessary to construct a distribution network capacitance and current test circuit model, which includes a signal injection module, a distribution network-to-ground capacitance module, an arc suppression coil module and a distribution network three-phase power supply; wherein, the signal injection module includes a voltage transformer, and the test current i is injected into the test circuit through the secondary side of the voltage transformer, the distribution network-to-ground capacitance module includes a three-phase-to-ground capacitance, and the arc suppression coil module includes an inductor.

[0016] Step S2: Collecting the injected current i 1. i 2. i Frequency of 3 oh 1. oh 2. oh 3. Amplitude I 1. I 2. I 3 and Phase f i1. f i2, f i3, and the voltage amplitude on the secondary side of the voltage transformer U 1. U 2. U 3 and phase f u1, f u2, f u3; Step S3: Calculate the impedance corresponding to the equivalent model under three injection currents Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p 3; In this step, the impedance Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p The calculation expression of 3 is: , where , , They represent the phase of the secondary voltage of the voltage transformer at three different frequencies. , , Respectively represent the measured current phases of three different frequencies.

[0017] Step S4: Calculate the value of the distribution network-to-ground capacitance C based on the acquired measurement circuit equivalent impedance.

[0018] In this step, specifically, the calculation expression of the distribution network ground capacitance C is: .

[0019] According to the online measurement technology proposed in the above embodiment, Table 1 shows the comparison results of the measured values ​​and actual values ​​of different capacitance sizes; at the same time, in order to further verify the superiority of the measurement technology proposed in the present invention over the existing measurement technology, the same capacitance is measured under the same measurement conditions using the existing measurement technology to obtain the actual measurement results of the distribution network to ground capacitance and the corresponding error value. The verification results are shown in Table 2.

[0020] Table 1: Measurement results based on the online measurement technology proposed by the present invention Table 2: Measurement results based on traditional triple-frequency measurement technology By comparing Table 1 and Table 2, it can be seen that the measurement accuracy of the distribution network's capacitance to the ground under the traditional measurement technology is low, which is not enough to perform real-time and accurate measurement of the distribution network's capacitance to the ground. The measurement technology proposed in the embodiment of the present application can realize high-precision real-time measurement of the distribution network's capacitance to the ground. Therefore, the online measurement technology proposed in the present application can realize online and accurate real-time measurement of the arc suppression coil capacitance and current, effectively ensuring the safe and stable operation of the distribution network.

[0021] The terms "first", "second", "third", etc. in the specification and claims of the present application and the drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a series of steps or units are included, or optionally, steps or units not listed are included, or optionally, other steps or units inherent to these processes, methods, products or devices are included.

[0022] Only the part relevant to the present application is shown in the accompanying drawings, but not all of the content. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processing or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of each operation can be rearranged. When its operation is completed, the process can be terminated, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0023] The terms "component", "module", "system", "unit", etc. used in this specification are used to represent computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a unit can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or distributed between two or more computers. In addition, these units can be executed from various computer-readable media having various data structures stored thereon. Units can communicate through local and / or remote processes, for example, based on signals having one or more data packets (e.g., data from a second unit interacting with another unit in a local system, a distributed system, and / or a network. For example, the Internet interacts with other systems via signals).

[0024] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0025] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Mentioning "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present embodiment application. The appearance of this phrase in various positions in the specification is not necessarily the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

[0027] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the disclosure disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

Claims

1. A method for online measurement of arc suppression coil current, characterized in that: include: Step S1: Inject three different frequencies of measurement current into the secondary side of the voltage transformer i 1. i 2. i 3; Step S2: Collecting the injected current i 1. i 2. i Frequency of 3 ω 1. ω 2. ω 3. Amplitude I 1. I 2. I 3 and Phase φ i1. φ i2, φ i3, and the voltage amplitude on the secondary side of the voltage transformer U 1. U 2. U 3 and phase φ u1, φ u2, φ u3; Step S3: Calculate the impedance corresponding to the equivalent model under three injection currents Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p 3; Step S4: Calculate the value of the distribution network-to-ground capacitance C based on the acquired measurement circuit equivalent impedance.

2. The arc suppression coil current online measurement method according to claim 1 is characterized in that: The impedance corresponding to the equivalent model under the three injection currents is calculated Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p 3. Including: The impedance Z 1. Z 2. Z Amplitude of 3 M 1. M 2. M 3 and Phase p 1. p 2. p The calculation expression of 3 is: , where , , They represent the phase of the secondary voltage of the voltage transformer at three different frequencies. , , Respectively represent the measured current phases of three different frequencies.

3. The arc suppression coil current online measurement method according to claim 1 is characterized in that: The step of calculating the value of the capacitance C of the distribution network to the ground according to the obtained equivalent impedance of the measurement circuit includes: The calculation expression of the distribution network to ground capacitance C is: 。 4. The arc suppression coil current online measurement method according to claim 1 is characterized in that: The measurement currents of three different frequencies are injected into the secondary side of the voltage transformer. i 1. i 2. i 3. It also includes: constructing a distribution network capacitance and current test circuit model.

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