CN214225394U

CN214225394U - Test system for power distribution cabinet or cable branch box

Info

Publication number: CN214225394U
Application number: CN202022455161.3U
Authority: CN
Inventors: 盛志平; 李红涛
Original assignee: Extra High Voltage Power Transmission Co
Current assignee: Extra High Voltage Power Transmission Co
Priority date: 2020-10-29
Filing date: 2020-10-29
Publication date: 2021-09-17
Anticipated expiration: 2030-10-29

Abstract

The embodiment of the present disclosure provides a test system for a power distribution cabinet or a cable branch box, the test system including: a first transformer; adjusting impedance; and an energy storage power source coupled between the power supply source and the high voltage side of the first transformer, the energy storage power source comprising a power module, the power module comprising a plurality of phase circuits, each phase circuit comprising a plurality of power cells, each power cell comprising an energy storage capacitor and an inverter coupled to each other, the energy storage capacitor being configured to store electrical energy from the power supply source, the inverter being configured to output the stored electrical energy, the inverters of the plurality of power cells being sequentially connected in series at an output, and the energy storage power source further comprising a switching device configured to connect at least two phase circuits of the plurality of phase circuits in series and/or in parallel to match the energy storage power source with the number of phases and the capacity of the power distribution cabinet or the cable branch box. The utility model discloses effectively improve test effect and be applicable to different switch boards and cable branch box on a wider range.

Description

Test system for power distribution cabinet or cable branch box

Technical Field

The present disclosure relates to the field of power distribution technologies, and more particularly, to a test system for a power distribution cabinet or a cable branch box.

Background

Switch board and cable branch case all by wide application in distribution network. A power distribution cabinet such as a JP cabinet (comprehensive power distribution cabinet of a distribution transformer) has the functions of electric energy distribution, metering, protection, control, reactive compensation and the like, and can be used in occasions such as transformer substations, factories, buildings and the like. The cable branch box is mainly used for branching or switching cables, namely, a main cable can be used for conveying electric energy generally, and then when a load is approached, the main cable can be branched to a plurality of small cables by using the cable branch box, and the small cables are connected to the load; or for long-distance cable lines (e.g., over 1000 meters), a cable breakout box may be used for the switchover. For example, a 0.4kV cable branch box is widely used for the cabling transformation of the urban power grid.

Distribution cabinets (such as JP cabinets) and cable branch boxes (such as 0.4kV cable branch boxes) may experience short circuit faults in use, with short circuit fault currents that may reach tens of kiloamperes. Therefore, in order to ensure that the power distribution cabinet and the cable branch box do not affect the use after short circuit removal after short circuit fault occurs, the short-time tolerance strength of the power distribution cabinet and the cable branch box is required to meet certain requirements. In order to verify whether the short-time withstand strength of the power distribution cabinet and the cable branch box meets the design requirements, the short-time withstand strength can be detected through tests or tests. However, the required short-circuit fault current (which may be as high as several tens of kiloamperes) may not be available in the existing test system, which results in that the test results do not necessarily truly reflect the short-time withstand strength of the distribution cabinets and cable branch boxes, and the test system needs to generate a higher current when operating, which may affect the safety or stability of the power grid supplying it. In addition, the existing test system with high cost has a limited application range when testing or experimenting different power distribution cabinets and cable branch boxes, so that the cost effectiveness is low in practice.

SUMMERY OF THE UTILITY MODEL

In order to at least partially solve the above and other possible problems, embodiments of the present disclosure provide a test system for a power distribution cabinet or a cable branch box, which can effectively improve the test effect of the power distribution cabinet and the cable branch box and can be applied to a wider range of different power distribution cabinets and cable branch boxes.

According to an aspect of the present disclosure, there is provided a test system for a power distribution cabinet or a cable breakout box, the test system including: a first transformer comprising a high voltage side and a low voltage side and configured to be coupled at the low voltage side to an input side of a switch cabinet or a cable breakout box; a regulated impedance coupled between an output side of the power distribution cabinet or the cable breakout box and ground; and an energy storage power supply coupled between the power supply and the high voltage side of the first transformer, the energy storage power supply configured to receive an input having a first capacity from the power supply for a first length of time and to provide an output having a second capacity for a second length of time less than the first length of time, the second capacity being greater than the first capacity, the energy storage power supply comprising a power module comprising a plurality of phase circuits, each phase circuit comprising a plurality of power cells, each power cell comprising an energy storage capacitor and an inverter coupled to each other, the energy storage capacitor configured to store electrical energy from the power supply, the inverters configured to output the stored electrical energy, each inverter of the plurality of power cells being connected in series at the output in turn, and the energy storage power supply further comprising switching means configured to connect at least two phase circuits of the plurality of phase circuits in series and/or parallel at the output, so that the phase number and the capacity of the energy storage power supply and the power distribution cabinet or the cable branch box are matched.

In some embodiments of the present disclosure, the energy storage power supply further comprises a second transformer configured to provide boosted ac power from the power supply to the power module.

In certain embodiments of the present disclosure, each of the plurality of power cells further comprises a rectifier configured to convert ac power from the power supply to dc power for provision to the corresponding energy storage capacitor.

In certain embodiments of the present disclosure, the first capacity is less than 100 kilo volt-amperes and the second capacity reaches tens of thousands of kilo volt-amperes.

In certain embodiments of the present disclosure, the first transformer provides 420 volts to the distribution cabinet or the cable branch box and tens of kiloamperes of current.

In certain embodiments of the present disclosure, the energy storage power supply is configured to receive an ac voltage of 380 volts from the power supply and output an ac voltage of 10 kilovolts to the first transformer.

In certain embodiments of the present disclosure, the adjusted impedance includes a resistor and an inductor connected in series, the adjusted impedance having a changeable impedance mode and an impedance angle.

In certain embodiments of the present disclosure, the test system further comprises: a measuring device disposed on a line between the first transformer and an input side of the distribution cabinet or the cable breakout box, the measuring device configured to detect at least one of a voltage, a current, and a power.

In certain embodiments of the present disclosure, the test system further comprises: and the isolating switch is coupled between the energy storage power supply and the first transformer.

In certain embodiments of the present disclosure, the test system is used to implement a short-time withstand strength test of a power distribution cabinet or a cable breakout box.

The summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. The summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure.

Drawings

The foregoing and other objects, features and advantages of the disclosure will be apparent from the following more particular descriptions of exemplary embodiments of the disclosure as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the disclosure.

Fig. 1 shows a test system 100 for a power distribution cabinet or a cable breakout box according to an embodiment of the present disclosure.

Fig. 2 illustrates an exemplary circuit block diagram of the energy storage power supply 110 of the test system 100 according to an embodiment of the disclosure.

Fig. 3 shows a detailed circuit diagram of the power module 113 and the switching device 114 in the energy storage power supply 110.

Fig. 4 shows a detailed circuit diagram of each power cell in the power module 113.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Alternative embodiments will become apparent to those skilled in the art from the following description without departing from the spirit and scope of the disclosure.

The term "include" and variations thereof as used herein is meant to be inclusive in an open-ended manner, i.e., "including but not limited to". Unless specifically stated otherwise, the term "or" means "and/or". The term "based on" means "based at least in part on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". Other explicit and implicit definitions are also possible below.

Embodiments of the present disclosure provide improved test systems for power distribution cabinets or cable breakout boxes. The energy storage power supply with low-capacity input and short-time high-capacity output can obtain the test capacity of thousands of volt-ampere under the condition of not influencing a power supply or a power supply grid, and the energy storage power supply of the test system can be correspondingly adjusted according to a power distribution cabinet or a cable branch box to be tested, so that the phase number and the capacity of the test system and the power distribution cabinet or the cable branch box to be tested are matched. Therefore, the test system disclosed by the invention can truly reproduce a short-circuit fault state, so that whether the short-time tolerance strength of the power distribution cabinet or the cable branch box to be tested meets the requirement or not can be reliably verified, and the test system can be used for testing various types (such as different capacities and different phase numbers) of power distribution cabinets or cable branch boxes, so that the application range is larger compared with the existing test system.

Fig. 1 shows a test system 100 for a power distribution cabinet or a cable breakout box according to an embodiment of the present disclosure. The test system 100 is shown as a three-phase system, but it is understood that the test system 100 shown in FIG. 1 is merely exemplary, and that the test system 100 may be any number of phase systems depending on the test object.

According to an embodiment of the present disclosure, the test system 100 may comprise a first transformer 130, the first transformer 130 comprising a high voltage side and a low voltage side and being configured to be coupled at the low voltage side to an input side of a power distribution cabinet or a cable breakout box 180. Specifically, the first transformer 100 may be a step-down transformer, so as to transform an input high voltage into a low voltage and transform an input low current into a high current close to a short-circuit fault current to be provided to the distribution cabinet or the cable breakout box 180 to be tested. In certain embodiments of the present disclosure, the first transformer 130 provides 420 volts and tens of kiloamperes of current to the distribution cabinet or the cable breakout box 180. Thus, test system 100 can provide voltage and current to JP cabinets and 0.4kV cable breakout boxes that are close to their true short-circuit fault conditions.

In an embodiment of the present disclosure, the test system 100 may include a conditioning impedance 170, the conditioning impedance 170 being coupled between an output side of a power distribution cabinet or cable breakout box 180 and ground. In particular, the tuning impedance 170 may have a predetermined impedance mode and impedance angle, and thus, may provide the measurement system 100 with the impedance magnitude and power factor required for testing. In certain embodiments of the present disclosure, the adjusting impedance 170 includes resistors Rta, Rtb, Rtc and inductors Lta, Ltb, Ltc connected in series, respectively, the adjusting impedance 170 having a changeable impedance mode and an impedance angle. Specifically, the adjustment impedance 170 may be composed of a resistor and an inductor connected in series, and the size of the resistor and the inductor may be changed so that the impedance mode and the impedance angle are adjusted according to the test power factor and the test object to obtain a desired test effect.

According to an embodiment of the present disclosure, the test system 100 may include a storage power supply 110, the storage power supply 110 may be coupled between a power supply and a high voltage side of the first transformer 130, the storage power supply 110 configured to receive an input having a first capacity from the power supply for a first length of time and to provide an output having a second capacity, greater than the first capacity, for a second length of time less than the first length of time. Specifically, when a short-circuit fault test is performed on a power distribution cabinet and a cable branch box, although a short-circuit fault current or a capacity required by a test is large, a duration (i.e., a test or test duration) in a large-current and large-capacity state is often short. Thus, the energy storage power source 110 can obtain a lower capacity input from a power supply source (e.g., a distribution grid) and output at a large capacity within a required short time (e.g., 1 second) after a certain amount of energy storage, so that a desired test capacity and current can be obtained on the distribution cabinet and the cable branch box to be tested.

In certain embodiments of the present disclosure, the first capacity is less than 100 kilo volt-amperes and the second capacity reaches tens of thousands of kilo volt-amperes. For example, the energy storage power supply 110 may be coupled to a power distribution grid below 100 kilovolt-ampere input and go through a long energy storage process and then output at a capacity of up to tens of thousands of kilovolt-amperes in a short time (e.g., 1 second) to meet the testing requirements of a typical JP cabinet and 0.4kV cable breakout box.

Fig. 2 illustrates an exemplary circuit block diagram of the energy storage power supply 110 of the test system 100 according to an embodiment of the disclosure. Fig. 3 shows a detailed circuit diagram of the power module 113 and the switching device 114 in the energy storage power supply 110. Fig. 4 shows a detailed circuit diagram of each power cell in the power module 113. The stored energy power supply 110 will be described below in conjunction with fig. 2, 3, and 4.

According to an embodiment of the present disclosure, the energy storage power source 110 may include a power module 113, the power module 113 may include a plurality of phase circuits, each phase circuit includes a plurality of power cells, each power cell includes an energy storage capacitor 1132 and an inverter 1133 coupled to each other, the energy storage capacitor 1132 is configured to store electric energy from the power supply, the inverter 1133 is configured to output the stored electric energy, and the inverters 1133 of the plurality of power cells are sequentially connected in series at an output terminal.

As an example, the power module 113 may include an array of power cells. Referring to fig. 4, each power cell may include an energy storage capacitor 1132 that performs an energy storage function, and the energy storage capacitor 1132 may store enough power from a power supply source (e.g., a power distribution grid with a lower capacity output) before the test starts (or during the test) and output the power through the inverter 1133 with a larger capacity during the test (i.e., for a short time). The inverter 1133 may convert the stored electrical energy in the form of direct current to electrical energy in the form of alternating current for provision to the distribution cabinet and the cable breakout box to be tested. The inverter 1133 may be a bridge circuit formed from semiconductor switching devices that may include Insulated Gate Bipolar Transistors (IGBTs), junction gate field effect transistors (JFETs), Bipolar Junction Transistors (BJTs), Metal Oxide Semiconductor Field Effect Transistors (MOSFETs), silicon MOSFETs, gate turn-off thyristors (GTOs), MOS Controlled Thyristors (MCTs), Integrated Gate Commutated Thyristors (IGCTs), silicon carbide (SiC) switching devices, or gallium nitride (GaN) switching devices. As an example, when an SPWM (sinusoidal pulse width modulation) pulse signal is applied to the gate of the semiconductor switching device, the output terminal of the inverter 1133 can obtain a single-phase sine wave pulse width modulation output voltage, and changing the fundamental frequency of the SPWM signal can realize an output frequency such as 0.01Hz to 300Hz, whereby different output voltages and output frequencies can be obtained according to the requirements.

Referring to fig. 3, in each phase circuit, respective inverters of a plurality of power cells are sequentially connected in series at an output terminal, whereby the plurality of power cells form a cascade structure. The advantage of this arrangement is that when each power cell input voltage is V₁After N power units are formed into a cascade structure, N multiplied by V can be obtained between the head end of the first power unit and the tail end of the last power unit₁The high voltage output of the volts, and thus, by selecting the number of power cells, power modules 113 can be assembled that meet different voltage requirements.

According to an embodiment of the present disclosure, the energy storage power supply 110 may include a switching device 114, and the switching device 114 is configured to connect at least two phase circuits of the plurality of phase circuits in series and/or in parallel to match the energy storage power supply 110 with the number of phases and the capacity of the power distribution cabinet or the cable branch box 180. As an example, as shown in fig. 3, the switching device 114 may be disposed at both ends of the output of the power module 113, whereby the upper output terminal and the lower output terminal of each phase circuit of the power module 113 may be connected to the switching device 114, and the switching device 114 may arbitrarily combine the series connection and the parallel connection of a plurality of phase circuits. For example, when the test object is a single-phase device, a plurality of phase circuits may be connected in parallel to obtain a larger output current, or a plurality of phase circuits may be connected in series to obtain a larger output voltage. For example, some phase circuits in the multiple phase legs may be connected in series and in parallel according to test requirements. The switching device 114 may be implemented by a contactor. It will be appreciated that the switching device 114 may also be implemented by other suitable electrical switches. By providing the switching device 114, the power module 113 of the energy storage power supply 110 can be configured more flexibly, so that the test system 100 including the energy storage power supply 110 can have a wider application range and flexibility.

In certain embodiments of the present disclosure, the energy storage power supply 110 includes a second transformer 112, the second transformer 112 configured to provide boosted ac power from the power supply to the power module 113. As an example, the second transformer 112 may be a step-up transformer, converting a lower voltage input from the distribution grid to a higher voltage output. In addition, the energy storage power source 110 may further include an input switch 111 and an output switch 115, wherein the input switch 111 is used for controlling the connection of the energy storage power source 110 with the power supply source, and the output switch 115 is used for controlling the connection of the energy storage power source 110 with the rear device (e.g., the first transformer 130) of the test system 100.

In certain embodiments of the present disclosure, each of the plurality of power cells further includes a rectifier 1131, the rectifier 1131 configured to convert ac power from the power supply to dc power for provision to the corresponding energy storage capacitor 1132. Specifically, energy storage capacitor 1132 is typically coupled to a dc bus and receives a dc power input, while a power supply source, such as a power grid, typically outputs ac power. The rectifier 1131 may rectify ac power from an ac power source into dc power and provide the dc power to the energy storage capacitor 1132. It is understood that, if desired, a suitable dc power supply may be directly coupled to the energy storage capacitor 1132 without providing any rectifier.

In certain embodiments of the present disclosure, the energy storage power supply 110 may be configured to receive an ac voltage of 380 volts from the power supply and output an ac voltage of 10 kv to the first transformer 130.

In certain embodiments of the present disclosure, the test system 100 may further include a measurement device disposed on a line between the first transformer 130 and an input side of the distribution cabinet or the cable breakout box 180, the measurement device configured to detect at least one of voltage, current, and power. As an example, the test apparatus may include a voltage measurement device 140, a current measurement device 150, and an analyzer 160. For example, the voltage measurement device 140 may be a voltage divider that may include upper resistors RHa, RHb, and RHc and lower resistors RLa, RLb, and RLc; the current measuring device 150 may include a rogowski coil; and the analyzer 160 may comprise a waveform recorder. The voltage measurement device 140 and the current measurement device 150 may send the voltage and current measurements to the analyzer 160 to record and analyze whether the test parameters meet the requirements of the test or experiment.

In certain embodiments of the present disclosure, the test system 100 may further include an isolation switch 120, the isolation switch 120 being coupled between the energy storage power supply 110 and the first transformer 130. In particular, the isolation switch 120 may be used to control whether the energy storage power supply 110 is coupled to the distribution cabinet or the cable breakout box 180 to be tested, so as to effectively control the start and end of the test.

In certain embodiments of the present disclosure, the test system 100 is used to implement a short-time withstand strength test of a power distribution cabinet or cable breakout box 180. The test system 100 can obtain a large-capacity output and a high current required for a short-time withstand strength test and obtain a reliable test analysis result without affecting a power supply grid.

In the embodiment of the disclosure, by providing the flexibly configurable energy storage power supply in the test system, high-capacity output close to a real fault condition can be obtained under the condition of low-capacity input, and the test system can be matched with power distribution cabinets and cable branch boxes with different capacities and phases, so that the application range of the test system is expanded, and the effectiveness of test analysis is improved.

Many modifications and other embodiments of the disclosure set forth herein will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiments of the disclosure are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the disclosure. Moreover, while the above description and the related figures describe example embodiments in the context of certain example combinations of components and/or functions, it should be appreciated that different combinations of components and/or functions may be provided by alternative embodiments without departing from the scope of the present disclosure. In this regard, for example, other combinations of components and/or functions than those explicitly described above are also contemplated as within the scope of the present disclosure. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A test system for a power distribution cabinet or a cable breakout box, the test system comprising:

a first transformer (130) comprising a high voltage side and a low voltage side and configured to be coupled to an input side of the switch cabinet or cable breakout box (180) at the low voltage side;

a conditioning impedance (170) coupled between an output side of the switch cabinet or cable breakout box (180) and ground; and

an energy storage power supply (110) coupled between a power supply and a high voltage side of the first transformer (130), the energy storage power supply (110) including an input adapted to receive a first capacity input from the power supply for a first length of time, and an output adapted to provide a second capacity output for a second length of time less than the first length of time, the second capacity being greater than the first capacity, the energy storage power supply (110) comprising:

a power module (113) comprising a plurality of phase circuits, each phase circuit comprising a plurality of power cells, each power cell comprising a storage capacitor (1132) and an inverter (1133) coupled to each other, the storage capacitor (1132) being configured to store electrical energy from the power supply, the inverter (1133) being configured to output the stored electrical energy, the respective inverters (1133) of the plurality of power cells being connected in series in sequence at an output, and

a switching device (114) configured to connect at least two of the plurality of phase circuits in series and/or in parallel to match the energy storage power supply (110) to the number of phases and the capacity of the switch cabinet or cable breakout box (180).

2. The test system of claim 1, wherein the energy storage power supply (110) further comprises a second transformer (112), the second transformer (112) being configured to provide boosted ac power from the power supply to the power module (113).

3. The test system of claim 1, wherein each of the plurality of power cells further comprises a rectifier (1131), the rectifier (1131) configured to convert alternating current power from the power supply to direct current power for provision to the corresponding energy storage capacitor (1132).

4. The test system of claim 1, wherein the first capacity is less than 100 kilo-volt-amperes and the second capacity reaches tens of thousands of kilo-volt-amperes.

5. The test system according to claim 1, characterized in that the first transformer (130) provides a voltage of 420 volts and a current of tens of kiloamperes to the switch board or cable breakout box (180).

6. The testing system of claim 1, wherein the energy storage power supply (110) is configured to receive an alternating voltage of 380 volts from the power supply and output an alternating voltage of 10 kilovolts to the first transformer (130).

7. The test system of claim 1, wherein the conditioning impedance (170) comprises a resistor and an inductor connected in series, the conditioning impedance (170) having a changeable impedance mode and impedance angle.

8. The test system of claim 1, further comprising:

a measuring device (140, 150, 160) arranged on a line between the first transformer (130) and an input side of the switch cabinet or cable breakout box (180), the measuring device (140, 150, 160) being configured to detect at least one of voltage, current and power.

9. The test system of claim 1, further comprising:

an isolation switch (120) coupled between the energy storage power source (110) and the first transformer (130).

10. The test system according to claim 1, characterized in that it is used to carry out a short-time withstand strength test of the switch cabinet or cable breakout box (180).