CN214225346U

CN214225346U - Test system for switchgear

Info

Publication number: CN214225346U
Application number: CN202022453143.1U
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

Embodiments of the present disclosure provide a test system for a switchgear. The test system comprises: the device comprises an energy storage power supply (10), a step-down transformer (30) and a test loop. The test loop is configured to be suitable for connecting the switching device (20) to provide the switching device (20) with a current for short circuit performance testing. An energy storage power supply (10) includes a first phase leg (12), a second phase leg (14), and a third phase leg (16), each phase leg including a plurality of power cells (100). According to the test system of the embodiment of the disclosure, the performance test of the switch device can be realized at low cost.

Description

Test system for switchgear

Technical Field

Embodiments of the present disclosure relate to a test system for a switchgear.

Background

Switching devices are widely used in power distribution networks of power systems for circuit monitoring and protection of the power distribution network, and play an important role in the operation of the power systems. For safety reasons, different countries and/or regions have strict standards and regulations for the performance of the switchgear, for example, the switchgear must have breaking capacity at a required limit short-circuit current, short-time current-withstanding capacity, and the like. A test system of a switching device is used to perform a performance test on the switching device, and it is necessary to provide various conditions for the performance test of the switching device.

However, the conventional testing system usually needs a short-circuit impact testing system powered by a generator set to provide short-time impact current, the short-circuit impact testing system comprises a motor, a generator and other devices, and the whole system needs auxiliary devices such as lubrication, protection and barring due to the fact that the rotating motor is contained, so that the system is very expensive in manufacturing cost.

It is therefore desirable to provide a low cost test system for switchgear.

Disclosure of Invention

In view of the above, it is an object of the embodiments of the present disclosure to provide a testing system for a switchgear, which can solve at least one or more of the above-mentioned technical problems in the prior art.

According to a first aspect of the present disclosure, a test system for a switchgear is provided. The test system comprises: an energy storage power supply comprising a three-phase ac power input adapted to receive an input of a first capacity and a three-phase ac power output adapted to provide an output of a second capacity greater than the first capacity; a step-down transformer coupled to an alternating current output of the energy storage power supply; and a test loop coupled to the step-down transformer, wherein the test loop is configured to connect the switching device to provide the switching device with current for short circuit performance testing; wherein the energy storage power supply includes first phase branch road, second phase branch road and third phase branch road, wherein every phase branch road in first phase branch road, second phase branch road and the third phase branch road includes a plurality of power unit, and wherein every power unit includes: an input coupled to a three-phase alternating current; a rectifier circuit coupled to the input and configured to convert the three-phase alternating current to direct current; a tank circuit configured to store direct current; an inverter coupled to the tank circuit and configured to convert power from the tank circuit into alternating current; and an output coupled to the inverter.

By using the test system according to the embodiment of the disclosure, high-capacity output can be conveniently improved. In particular, by applying a modulation signal to the control electrode of the power cell, an output voltage of a desired frequency and amplitude can be conveniently output, and when a plurality of power cells are cascaded, a multi-level total output voltage of the number of cells multiplied by the cell voltage can be obtained. In addition, the required three-phase alternating-current voltage can be output through the wiring of each phase branch. In some embodiments, the number of power units that meet the requirement may be selected according to the required output voltage.

According to one embodiment of the present disclosure, the output terminals of the plurality of power cells on each phase leg are connected in series with each other, and the output terminals of the first phase leg, the second phase leg, and the third phase leg are wye-connected.

According to an embodiment of the present disclosure, the test system further comprises an output contactor connected to the first phase leg, the second phase leg and the third phase leg, wherein the energy storage power source is configured to output three-phase alternating current for testing via the output contactor.

According to an embodiment of the present disclosure, the energy storage power supply includes a cabinet for accommodating the first phase branch, the second phase branch, and the third phase branch, wherein the first phase branch, the second phase branch, and the third phase branch are arranged side by side in the cabinet in a cabinet unit manner, the cabinet further includes a panel in which the three-phase alternating current input terminal and the three-phase alternating current output terminal are embedded.

According to one embodiment of the present disclosure, each of the first, second and third phase legs includes an LC filter, respectively.

According to an embodiment of the disclosure, the current is in a range between 10-100 times a rated current of the switching device.

According to one embodiment of the present disclosure, the switchgear includes a circuit breaker, a high voltage switchgear, a ring main unit, or a pole top switchgear.

According to one embodiment of the present disclosure, the tank circuit includes a tank capacitor having a capacitance of 1 μ F.

According to one embodiment of the present disclosure, the first capacity is less than 100kVA and the second capacity is in a range of 3kVA to 10 kilo kVA.

According to an embodiment of the present disclosure, the test loop comprises a measurement unit adapted to measure an electrical parameter of the test loop. The measuring unit comprises a current measuring unit adapted to detect a current of the test loop and/or a voltage measuring unit adapted to detect a voltage of the test loop. According to one embodiment of the present disclosure, the current measuring unit includes a rogowski coil, and the voltage measuring unit includes a first voltage dividing resistor and a second voltage dividing resistor connected in parallel with the test loop.

According to an embodiment of the present disclosure, the test system further comprises a waveform recorder adapted to observe and/or record the measurement parameters of said measurement unit.

According to one embodiment of the present disclosure, the test system further comprises an isolation switch coupled between the energy storage power supply and the step-down transformer.

According to the test system disclosed by the invention, the performance test of the switch equipment can be realized at low cost.

Drawings

Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows a test system circuit schematic for a switchgear in accordance with an embodiment of the present disclosure;

FIG. 2 shows an internal circuit schematic of an energy storage power supply according to an embodiment of the disclosure; and

fig. 3 shows a circuit schematic of a power cell of an energy storage power supply according to an embodiment of the disclosure.

Fig. 4 shows an overall structural schematic diagram of an energy storage power supply according to an embodiment of the disclosure.

Detailed Description

Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals may be used in the drawings for similar components or functional elements. The accompanying drawings are only intended to illustrate embodiments of the present disclosure. 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.

A test system circuit schematic for a switchgear according to an embodiment of the present disclosure is described below with reference to the accompanying drawings.

As shown in fig. 1, a test system 100 for a switchgear includes an energy storage power supply 10, a step-down transformer 30, and a test loop. The test loop may be connected to the switching device 20. The energy storage power supply 10 may be configured to provide a short-term, large capacity output. In some embodiments, the short-time large capacity output may be up to ten thousand kVA or even hundreds of thousands kVA.

The switch device can be connected in series in the test loop, and the performance test can be carried out on the switch device by using the test loop. In some embodiments, the switchgear may include circuit breakers, high voltage switchgear, ring main units, column switchgear, disconnectors, and the like. These switching devices are provided in the grid for providing protection to the grid. When a short-circuit fault occurs in a load circuit of the distribution network, dozens of times or dozens of times of short-circuit current flows in the load circuit through the switch device. The short-circuit current will cause the switching device to generate heat, possibly causing damage to the switching device.

In order to verify whether the switch equipment, such as a circuit breaker, a high-voltage switch cabinet, a ring main unit, a column switch equipment, a disconnecting switch and the like, is damaged or not during short circuit, the short-circuit performance of the switch equipment can be tested through short-time withstand current and peak withstand current tests.

In some embodiments, the size of the test circuit in the test loop through the switching device is tens of times, even tens of times, and in some embodiments, may be as high as hundreds of times the rated current of the switching device.

In some embodiments, the energy storage power supply 10 can provide a test capacity of up to ten thousand kVA, hundreds of thousands kVA, or even millions of kVA. As background art, the above-mentioned test capacity is difficult to achieve in a test condition environment that conventionally relies on a utility grid, and the conventional test system mainly relies on a complicated and expensive power supply system including a generator. The energy storage power supply provided by the embodiment of the disclosure can meet the test capacity requirement, and the cost of the test system can be greatly reduced. In some embodiments, the energy storage power supply 10 receives a low capacity input and is capable of providing a short duration high capacity output. The energy storage power supply 10 may include an energy storage capacitor, with which energy storage and short-term release of energy may be achieved. In some embodiments, the time for the energy storage power supply to output current is in the order of seconds. The low capacity input may be, for example, less than 100kVA, which may be provided, for example, by a mains electricity distribution network, and the high capacity output may be in the range of 3kVA to 10 kilo kVA; in other embodiments, the large capacity output may range from 30 kilo-kilo.

The output of the energy storage power supply 10 is stepped down by the step-down transformer 30, thereby converting the high-voltage low current of the primary coil into the low-voltage high current of the secondary coil. Therefore, power can be supplied to the test loop; the current output at the secondary side of the step-down transformer 30 may flow through the switching device 20 to test the short-circuit performance of the switching device.

When the test system according to the embodiment of the present disclosure is operated, the switching device may be set to a closing state. After testing, the contact resistance of the switchgear can be measured and the mechanical structure of the switchgear is observed, and the qualified switchgear should meet the requirements specified by the standard or specification.

In some embodiments, the test loop may comprise a measurement unit adapted to measure an electrical parameter of the test loop. In some embodiments, the measurement unit may comprise a current measurement unit adapted to detect the current of the test loop. As an example, in the illustrated embodiment, the current measurement unit may include a rogowski coil. It should be understood that this is merely exemplary and that the present disclosure may employ other current measuring units known in the art. In the illustrated embodiment, the three-phase power is provided with a current measuring unit, and in other embodiments, the current measuring unit may be provided in one or two phases of the three-phase power.

In other embodiments, the measurement unit may further comprise a voltage measurement unit 50 adapted to detect the voltage of the test loop. As an example, in the illustrated embodiment, the voltage measuring unit includes a first voltage-dividing resistor and a second voltage-dividing resistor connected in parallel with the test loop, and the voltage of the test loop may be measured by measuring a node voltage between the first voltage-dividing resistor and the second voltage-dividing resistor. It should be understood that this is merely exemplary and that the present disclosure may employ various other voltage measurement units known in the art. In the illustrated embodiment, the three-phase power is provided with a voltage measuring unit, and in other embodiments, the voltage measuring unit may be provided in one or two phases of the three-phase power.

According to one embodiment of the present disclosure, as shown, the test system further comprises a waveform recorder 60 adapted to observe and/or record the measurement parameters of the measurement unit. For example, the measurement unit may be connected to a waveform recorder 60, and the waveform recorder 60 may record and/or display the measurements for analysis of whether the test parameters meet the requirements. It should be understood that the waveform recorder is merely exemplary and that other measurement parameter recording units or display units may be used.

According to one embodiment of the present disclosure, as shown, the test system may further include an isolation switch 70. An isolation switch 70 may be coupled between the energy storage power supply 10 and the step-down transformer 30. Via the isolating switch 70, control and/or protection can be implemented for the test loop, ensuring the safety of the test.

The energy storage power supply according to the embodiment of the disclosure is explained in detail with reference to fig. 2 and 3. Fig. 2 shows an internal circuit schematic of the energy storage power supply 10 according to an embodiment of the disclosure. Fig. 3 shows a schematic structural diagram of a power cell 100 according to an embodiment of the present disclosure.

The energy storage power supply 10 may include an ac input terminal receiving a first capacity input and an ac output terminal A, B, C adapted to provide a second capacity output greater than the first capacity. In some embodiments, the ac input may be coupled to a mains power distribution network and the ac output A, B, C may be coupled to a test system or test loop according to embodiments of the present disclosure.

The energy storage power supply 10 may include a first phase leg 12, a second phase leg 14, and a third phase leg 16. Each of the first, second, and third phase legs 12, 14, 16 includes at least one power cell 100. In the illustrated embodiment, each phase leg includes a plurality of power cells 100.

The energy storage power supply 10 may include a phase shifting transformer (not shown). In the illustrated embodiment, a, b, c are a set of windings from a phase shifting transformer, and ac1, ac2 are the inverted outputs of the power cell. When SPWM pulse signals are applied to IGBT control electrodes g1, g2, g3 and g4, single-phase positive sine wave pulse width modulation output voltages can be obtained by the output ends ac1 and ac 2. The SPWM modulation signal is variable in frequency, for example the fundamental frequency can achieve an output frequency of 0.01Hz to 300 Hz. It should be understood that the above described inversion schemes are merely exemplary and that other inversion schemes known to those skilled in the art or developed in the future may be used.

As shown in fig. 3, each power cell 100 may include: an input 110 coupled to a three-phase alternating current; a rectifier circuit 120 coupled to the pair of input terminals and configured to convert the three-phase alternating current into direct current; a tank circuit 130 configured to store direct current; an inverter 140 coupled to the tank circuit 130 and configured to convert power from the tank circuit 130 into alternating current; and an output 150 coupled to the inverter 140.

The rectifying circuit 130 is adapted to convert alternating current received by the energy storage power supply 10 into direct current. In the illustrated embodiment, the rectification circuit 120 may include a full bridge rectifier bridge. The tank circuit 130 may include a tank capacitor. An appropriate energy storage capacitor may be selected according to the output capacity of the energy storage power supply 10. In some embodiments, the storage capacitor may be a 1 μ F storage capacitor. It should be understood that this is merely exemplary and one skilled in the art can select an appropriate capacity of the storage capacitor as desired. The inverter 140 is adapted to convert the power from the tank circuit 130 into alternating current. The frequency and waveform of the modulation signal of the inverter 140 are adjusted to obtain the desired output waveform and voltage.

According to an embodiment of the present disclosure, the output terminals of the N power cells of each phase are connected in series, where N is 1 or an integer greater than or equal to. A high voltage output of nxv 1 volts is available between the head end of the first power cell and the tail end of the last power cell. In some embodiments, the outputs of the three phase legs may be wye-wired. Thus, a three-phase N × V1 × √ 3 volt output power source can be obtained. In other embodiments, the outputs of the three phase legs may be wired in other ways known in the art.

In the illustrated embodiment, the respective outputs of the wye-connected first, second, and third phase legs 12, 14, 16 form a three-phase ac power output A, B, C.

In some embodiments, energy storage power supply 10 may include contactors (not shown) that may be utilized to implement a wiring configuration for three-phase ac power output A, B, C. In some embodiments, the three-phase ac power output A, B, C may be shorted to provide single-phase ac power. In this case, even if a single-phase output is used, the load asymmetry problem does not occur to the power supply. In addition, the single-phase output can fully utilize the three-phase power supply capacity of the power supply. The full capacity output can be achieved during single-phase and three-phase output. The single-phase and three-phase output modes are automatically switched without manually changing the wiring.

Fig. 4 shows an overall structural schematic diagram of the energy storage power supply 10 according to the embodiment of the disclosure. As shown, the energy storage power supply 10 is implemented as a structure of a cabinet 40 including a plurality of cabinet units. The power cells 100 are placed in the cabinet unit, and a plurality of the power cells 100 form respective phase legs; a plurality of cabinet units are arranged side by side to form the energy storage power supply 10. With such an arrangement, the modularity of the individual phase legs is facilitated, and the electrical connection is facilitated. In addition, such a structure may facilitate product assembly and transport. The cabinet of the energy storage power supply 10 further comprises panels adapted to enclose the individual cabinet units. The input terminal and the output terminal of the energy storage unit may be embedded in the panel to facilitate input and output of power.

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 switchgear, characterized in that it comprises

An energy storage power supply (10) comprising a three-phase ac input adapted to receive an input of a first capacity and a three-phase ac output adapted to provide an output of a second capacity greater than the first capacity;

a step-down transformer (30) coupled to the alternating current output of the energy storage power supply (10); and

a test loop coupled to the step-down transformer (30), wherein the test loop is configured to connect the switching device (20) to provide the switching device (20) with current for short circuit performance testing;

wherein the energy storage power supply (10) comprises a first phase leg (12), a second phase leg (14) and a third phase leg (16),

wherein each of the first phase leg (12), the second phase leg (14) and the third phase leg (16) comprises a plurality of power cells (100),

wherein each power cell (100) comprises:

an input (110) coupled to the three-phase alternating current;

a rectifier circuit (120) coupled to the input and configured to convert the three-phase alternating current to direct current;

a tank circuit (130) configured to store the direct current;

an inverter (140) coupled to the tank circuit (130) and configured to convert power from the tank circuit (130) into alternating current; and

an output (150) coupled to the inverter (140).

2. The test system according to claim 1, wherein the outputs (150) of the plurality of power cells (100) on each phase leg are connected in series with each other, and the outputs of the first phase leg (12), the second phase leg (14) and the third phase leg (16) are wye connected.

3. The test system according to claim 2, further comprising an output contactor connected to the first phase leg (12), the second phase leg (14) and the third phase leg (16), wherein the energy storage power supply (10) is configured to output three-phase alternating current for testing via the output contactor.

4. A test system according to claim 3, wherein each of the first phase branch (12), the second phase branch (14) and the third phase branch (16) comprises an LC filter, respectively.

5. The testing system according to any one of claims 1-4, wherein the energy storage power source (10) comprises a cabinet for housing the first phase leg (12), the second phase leg (14) and the third phase leg (16), wherein the first phase leg (12), the second phase leg (14) and the third phase leg (16) are arranged side by side in the cabinet in a cabinet unit, the cabinet further comprising a panel in which the three-phase alternating current input and the three-phase alternating current output are embedded.

6. Test system according to any of claims 1-4, characterized in that the current for short circuit performance testing is in the range between 10-100 times the rated current of the switching device (20).

7. The test system of any one of claims 1-4, wherein the switchgear comprises a circuit breaker, a high voltage switchgear, a ring main unit, or a pole top switchgear; the first capacity is less than 100kVA and the second capacity is in the range of 2kVA to 10 kilo-VA.

8. The test system according to any one of claims 1-4, wherein the test loop comprises a measurement unit adapted to measure an electrical parameter of the test loop, the measurement unit comprising a current measurement unit (40) adapted to detect a current of the test loop and/or a voltage measurement unit (50) adapted to detect a voltage of the test loop;

the current measuring unit comprises a Rogowski coil, and the voltage measuring unit comprises a first voltage dividing resistor and a second voltage dividing resistor.

9. The test system according to claim 8, further comprising a waveform recorder (60) adapted to observe and/or record the measurement parameters of the measurement unit.

10. The test system according to any one of claims 1-4, further comprising a disconnector (70) coupled between the energy storage power supply (10) and the step-down transformer (30).