Three-phase, single-phase and direct-current compatible adjustable load system and load adjusting method

Abstract

The invention relates to the technical field of electrical tests, in particular to an adjustable load system compatible with three-phase, single-phase and direct current and a load adjusting method. The system comprises a three-phase input switch, the input side of the three-phase input switch is connected with a three-phase alternating current input port, each item of the output side of the three-phase input switch is connected with a three-phase voltage bus, and a zero line is connected with a zero bus; the input side of the two-way low-voltage input switch is respectively connected with the positive electrode and the negative electrode of the direct-current input port, and the output side of the two-way low-voltage input switch is connected with the input port of the phase-combined switch and the zero bus; the output end of the parallel-phase switch comprises three ports, and the output end of the parallel-phase switch is connected to the three-phase voltage bus; the input side of the two-way high-voltage input switch is connected with the input side of the two-way low-voltage input switch in parallel, and the output side T of the two-way high-voltage input switch is connected to any two phases in the three-phase voltage bus; and the three-phase impedance loads are connected in parallel.

Description

Technical Field

[0001] The present application relates to the field of electrical testing technology, and in particular to an adjustable load system compatible with three-phase, single-phase and direct current, and a method for adjusting the load. Background Art

[0002] During the development, production and testing of various power supply equipment such as transformers, converters, battery packs, chargers, etc., it is usually necessary to conduct load tests to detect and assess the equipment's load capacity and performance indicators and reliability under different working conditions. It is also necessary to configure a load system that matches the characteristics of the object being tested. However, in production practice, since the equipment to be tested may be three-phase, single-phase or DC, and the output voltage and current range may vary greatly, the load system needs to be able to adapt to different types, voltage inputs, and flexible and adjustable loads. For example, the distribution network ice melting device currently has three-phase AC type, single-phase AC type, uncontrolled rectifier type, wide-range voltage regulation and conversion type, and the output voltage and current of each type vary greatly. In the process of debugging and maintenance of ice melting equipment, it is often necessary to test debugging under various output voltages and load currents. At this time, it is necessary to be compatible with high-power loads of various types of voltages, different amplitude voltages, and different currents.

[0003] To meet the requirements of load testing under different working conditions, the traditional method is to configure three-phase AC load, single-phase or DC load for different units under test with greatly different port characteristics. This will result in a large number of resistive loads being configured in the test platform, which takes up a large amount of space and has a high total cost. Summary of the invention

[0004] The purpose of the embodiment of the present application is to provide an adjustable load system that is compatible with three-phase, single-phase and DC, which can adapt to different AC and DC and different input voltages and load currents through switch switching without increasing the load rated power, thereby meeting the testing requirements of different equipment.

[0005] In order to achieve the above-mentioned object, the present application provides an adjustable load system compatible with three-phase, single-phase and DC, and the adjustable load system compatible with three-phase, single-phase and DC includes:

[0006] A three-phase input switch, the input side of the three-phase input switch is connected to the three-phase AC input port, each item on the output side of the three-phase input switch is connected to the three-phase voltage bus respectively, and the neutral line of the three-phase input switch is connected to the neutral bus;

[0007] A dual-channel low-voltage input switch, wherein the input side of the dual-channel low-voltage input switch is respectively connected to the positive and negative electrodes of the DC input port, and the output side of the dual-channel low-voltage output switch is connected to the input port of the parallel-phase switch and the zero bus;

[0008] A parallel-phase switch, wherein the output end of the parallel-phase switch comprises three ports, and the output ends of the parallel-phase switch are all connected to the three-phase voltage bus;

[0009] A dual-way high-voltage input switch, the input side of the dual-way high-voltage input switch is connected in parallel with the input side of the dual-way low-voltage input switch, and the output side T of the dual-way high-voltage input switch is connected to any two phases of the three-phase voltage bus; and

[0010] Multiple groups of three-phase impedance loads are connected in parallel, each group of three-phase impedance loads includes a three-phase symmetrical impedance unit connected in star, the input side of the three-phase impedance load is connected to the load drop-in / drop-out switch and connected to the three-phase voltage bus, and the common point of the three-phase impedance load is connected to the zero bus.

[0011] In an embodiment of the present application, the adjustable load system compatible with three-phase, single-phase and DC also includes: a dual-channel low-voltage input switch, the input side of the dual-channel low-voltage input switch is respectively connected to the neutral wire and the live wire of the unidirectional input port, and the output side of the dual-channel low-voltage output switch is connected to the input port of the parallel-phase switch and the neutral bus.

[0012] In an embodiment of the present application, an interlocking circuit is provided between the dual-way high-voltage switch and the dual-way low-voltage switch to prohibit the dual-way high-voltage switch and the dual-way low-voltage switch from being closed at the same time; an interlocking circuit is provided between the dual-way high-voltage switch and the three-phase input switch to prohibit the dual-way high-voltage switch and the three-phase input switch from being closed at the same time; an interlocking circuit is provided between the dual-way low-voltage switch and the three-phase input switch to prohibit the dual-way low-voltage switch and the three-phase input switch from being closed at the same time; an interlocking circuit is provided between the three-phase input switch and the parallel-phase switch to prohibit the three-phase input switch and the parallel-phase switch from being closed at the same time; an interlocking circuit is provided between the dual-way high-voltage input switch and the parallel-phase switch to prohibit the dual-way high-voltage input switch and the parallel-phase switch from being closed at the same time.

[0013] In an embodiment of the present application, the load throw-in / out switch includes a linkage load throw-in / out switch and a phase-split load throw-in / out switch. The load of the adjustable load system compatible with three-phase, single-phase and DC is adjusted by controlling the linkage load throw-in / out switch and / or the phase-split load throw-in / out switch.

[0014] In an embodiment of the present application, the dual-circuit low-voltage switch includes an overvoltage protection device.

[0015] In an embodiment of the present application, for any group of three-phase impedance loads, the minimum current of each impedance unit included in the three-phase impedance load is less than or equal to a preset minimum load current, wherein the preset minimum load current is determined based on the minimum input voltage; the sum of the total currents of all three-phase impedance loads is greater than or equal to a preset maximum load current, wherein the preset maximum load current is determined based on the maximum input voltage.

[0016] A second aspect of the present application provides a method for adjusting a load, which is applied to any of the above-mentioned adjustable load systems compatible with three-phase, single-phase and DC, and the method comprises:

[0017] According to the input voltage of the adjustable load system compatible with three-phase, single-phase and DC, the three-phase input switch, dual-channel low-voltage input switch, dual-channel high-voltage input switch, parallel-phase switch and load throw-in / out switches corresponding to multiple groups of parallel three-phase impedance loads are controlled to make the load of the adjustable load system within a preset value range, wherein the preset value range is determined according to the input voltage.

[0018] In an embodiment of the present application, the method includes: when the input voltage is the voltage provided by the three-phase power supply device, controlling the three-phase input switch to close, and the dual-way low-voltage input switch, the dual-way high-voltage input switch and the parallel-phase switch to open; controlling multiple load throw-in switches included in multiple groups of parallel three-phase impedance loads to adjust the first load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the first load current reaches the first preset load current corresponding to the three-phase power supply device.

[0019] In an embodiment of the present application, the method includes: when the input voltage is the voltage provided by the single-phase power supply device, obtaining the input voltage of the single-phase power supply device; when the input voltage is lower than the rated phase voltage of the load resistor of the adjustable load system compatible with three-phase, single-phase and DC, controlling the dual-way low-voltage input switch and the parallel-phase switch to close, and the three-phase input switch and the dual-way high-voltage input switch to open; controlling the multiple load throw-in switches included in the multiple groups of parallel three-phase impedance loads to adjust the second load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the second load current reaches the second preset load current corresponding to the single-phase power supply device; when the input voltage is higher than the rated phase voltage of the load resistor and lower than the preset multiple of the rated phase voltage of the load resistor, controlling the dual-way high-voltage input switch to close, and the dual-way low-voltage input switch, the parallel-phase switch and the three-phase input switch to open; controlling the multiple load throw-in switches included in the multiple groups of parallel three-phase impedance loads to adjust the third load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the third load current reaches the third preset load current corresponding to the single-phase power supply device.

[0020] In an embodiment of the present application, the method includes: when the input voltage is the voltage provided by the DC power supply device, obtaining the input voltage of the DC power supply device; when the input voltage is lower than the rated phase voltage of the load resistor of the adjustable load system compatible with three-phase, single-phase and DC, controlling the dual-way low-voltage input switch and the parallel-phase switch to close, and the three-phase input switch and the dual-way high-voltage input switch to open; controlling multiple load throw-in switches included in multiple groups of parallel three-phase impedance loads to adjust the fourth load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the fourth load current reaches the fourth preset load current corresponding to the DC power supply device; when the input voltage is higher than the rated phase voltage of the load resistor and lower than the preset multiple of the rated phase voltage of the load resistor, controlling the dual-way high-voltage input switch to close, and the dual-way low-voltage input switch, the parallel-phase switch and the three-phase input switch to open; controlling multiple load throw-in switches included in multiple groups of parallel three-phase impedance loads to adjust the fifth load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the fifth load current reaches the fifth preset load current corresponding to the DC power supply device.

[0021] Through the above technical solution, the adjustable load system compatible with three-phase, single-phase and DC can be compatible with three-phase input, single-phase input, DC input, high voltage and high current or low voltage and low current and other working conditions. When switching different input modes, only a small number of switches need to be adjusted, which is convenient and fast, avoiding tedious wiring work and high efficiency.

[0022] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0024] Figure 1 The schematic diagram shows a structure of an adjustable load system compatible with three-phase, single-phase and direct current according to an embodiment of the present application;

[0025] Figure 2 A schematic diagram showing the operating states of each switch unit when a three-phase unbalanced load is input to an adjustable load system compatible with three-phase, single-phase and direct current according to an embodiment of the present application;

[0026] Figure 3 A schematic diagram of the operating states of switches of an adjustable load system compatible with three-phase, single-phase and DC according to an embodiment of the present application when the input voltage is low and the output current is maximum is shown;

[0027] Figure 4The operating state diagram of each switch of an adjustable load system compatible with three-phase, single-phase and DC according to an embodiment of the present application is schematically shown when the input voltage is high and there is partial load.

[0028] Description of Reference Numerals

[0029] K1: three-phase input switch; K2: dual-channel low-voltage input switch; K3: parallel-phase switch; K4: dual-channel high-voltage input switch; R1, R2, R3: three-phase impedance load; A, B, C: three-phase voltage bus; N: neutral bus; K11, K12, K13: linkage load throw-in / out switch; K12a, K12b, K12c, K13c: split-phase load throw-in / out switch; V+: DC positive input port; V-: DC negative input port; I: single-phase live wire input port; N: single-phase neutral wire input port. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0033] Figure 1 The schematic diagram of the structure of an adjustable load system compatible with three-phase, single-phase and DC according to an embodiment of the present application is shown. Figure 1As shown, an embodiment of the present application provides an adjustable load system compatible with three-phase, single-phase and DC. The adjustable load system compatible with three-phase, single-phase and DC may include: a three-phase input switch K1, the input side of the three-phase input switch K1 is connected to the three-phase AC input port, and the items on the output side of the three-phase input switch K1 are respectively connected to the three-phase voltage bus A, B, and C, and the neutral line of the three-phase input switch K1 is connected to the neutral bus N; a dual-path low-voltage input switch K2, the input side of the dual-path low-voltage input switch K2 is respectively connected to the positive pole V+ and the negative pole V- of the DC input port, and the output side of the dual-path low-voltage output switch K2 is connected to the input port of the parallel-phase switch K3 and the neutral bus N; and the parallel-phase Switch K3, the output end of the parallel-phase switch K3 includes three ports, and the output ends of the parallel-phase switch K3 are all connected to the three-phase voltage bus A, B, and C; a dual-way high-voltage input switch K4, the input side of the dual-way high-voltage input switch K4 is connected in parallel with the input side of the dual-way low-voltage input switch K2, and the output side T of the dual-way high-voltage input switch K4 is connected to any two phases of the three-phase voltage bus A, B, and C; and multiple groups of parallel three-phase impedance loads, each group of three-phase impedance loads includes a star-connected three-phase symmetrical impedance load, the input side of the three-phase impedance load is connected to the load throw-in / out switch, and is connected to the three-phase voltage bus A, B, and C, and the common point of the star connection of the three-phase impedance load is connected to the zero bus N.

[0034] For example Figure 1 As shown, it is assumed that the adjustable load system compatible with three-phase, single-phase and DC includes three groups of three-phase impedance loads R1, R2, and R3 connected in parallel. Each group of three-phase impedance loads includes a three-phase symmetrical impedance unit connected in star connection. The input side of the three-phase impedance load is connected to the load throw-in / out switch, for example Figure 1 As shown, the input side of the three-phase impedance load R1 is connected to the load throw-in switch K11, and is connected to the three-phase voltage bus A, B, C through the load throw-in switch K11, and the common point of the three-phase impedance load R1 is connected to the zero bus N. The input side of the three-phase impedance load R2 is connected to the load throw-in switch K12, and is connected to the three-phase voltage bus A, B, C through the load throw-in switch K12. The output side of the load throw-in switch K12 can be connected to the three-phase voltage bus A, B, C respectively. For example, Figure 1 As shown, a load throw-in / out switch K12a is connected between the output side of the load throw-in / out switch K12 and the three-phase voltage bus A, a load throw-in / out switch K12b is connected between the output side of the load throw-in / out switch K12 and the three-phase voltage bus B, a load throw-in / out switch K12c is connected between the output side of the load throw-in / out switch K12 and the three-phase voltage bus C, and the common point of the three-phase impedance load R1 is connected to the zero bus N. The input side of the three-phase impedance load R3 is connected to the load throw-in / out switch K13, and a load throw-in / out switch can be connected between the output side of the load throw-in / out switch K13 and any one of the three-phase voltage buses A, B, and C, for example Figure 1As shown, a load throw-in switch K13c is connected between the output side of the load throw-in switch K13 and the three-phase voltage bus C, and the common point of the three-phase impedance load R1 connected in star connection is connected to the zero bus N. The adjustable load system compatible with three-phase single-phase and DC connects a variety of different load throw-in switches to the input side of multiple three-phase impedance loads, thereby adjusting the load current by opening and closing the load throw-in switches of each three-phase impedance load, so that the load current reaches the preset value set by the user or the expected value required by the user.

[0035] In one embodiment, the load throw-in / out switch includes a linkage switch and a phase-splitting switch, and the load of the adjustable load system compatible with three-phase, single-phase and DC is adjusted by controlling the linkage switch and / or the phase-splitting switch.

[0036] For example Figure 1 As shown, the load throw-in / out switches may include linked load throw-in / out switches K11, K12, K13, and phase-split load throw-in / out switches K12a, K12b, K12c, K13c. For example, when testing a three-phase balanced load, the phase-split load throw-in / out switches K12a, K12b, K12c, K13c corresponding to each group of three-phase impedance loads are closed simultaneously, and different load current sizes are obtained by closing the linked load throw-in / out switches K11, K12, K13 respectively. When testing a three-phase unbalanced load, the linked load throw-in / out switches K11, K12, K13 and the phase-split load throw-in / out switches K12a, K12b, K12c, K13c may be closed and controlled simultaneously according to the required unbalanced load type and size to obtain the required unbalanced load current.

[0037] In one embodiment, Figure 1 As shown, the adjustable load system compatible with three-phase, single-phase and DC also includes: a dual-channel low-voltage input switch K2, the input side of the dual-channel low-voltage input switch K2 is respectively connected to the neutral line N and the live line I of the single-phase input port, and the output side of the dual-channel low-voltage output switch K2 is connected to the input port of the parallel-phase switch K3 and the neutral bus N.

[0038] The dual input port included in the adjustable load system compatible with three-phase, single-phase and DC can be used as the input port of the neutral line N and the live line I of the unidirectional input port, and can also be used as the input port of the positive pole V+ and the negative pole V- of the DC input port. The input side of the dual low-voltage input switch K2 can be connected to the dual input port, and the output side is connected to the input port of the parallel phase switch K3 and the zero bus N.

[0039] In one embodiment, Figure 1As shown, the input switching switch is formed between the dual-way high-voltage switch K4, the three-phase input switch K1, the dual-way low-voltage switch K2 and the parallel-phase switch K3, and an anti-mistaken locking circuit is provided. An interlocking circuit is provided between the dual-way high-voltage switch K4 and the dual-way low-voltage switch K2 to prohibit the dual-way high-voltage switch K4 and the dual-way low-voltage switch K2 from being closed at the same time; an interlocking circuit is provided between the dual-way high-voltage switch K4 and the three-phase input switch K1 to prohibit the dual-way high-voltage switch K4 and the three-phase input switch K1 from being closed at the same time; an interlocking circuit is provided between the dual-way low-voltage switch K2 and the three-phase input switch K1 to prohibit the dual-way low-voltage switch K2 and the three-phase input switch K1 from being closed at the same time; an interlocking circuit is provided between the three-phase input switch K1 and the parallel-phase switch K3 to prohibit the three-phase input switch K1 and the parallel-phase switch K3 from being closed at the same time; an interlocking circuit is provided between the dual-way high-voltage input K4 switch and the parallel-phase switch K3 to prohibit the dual-way high-voltage input switch K4 and the parallel-phase switch K3 from being closed at the same time.

[0040] In one embodiment, the dual-way low voltage switch includes an overvoltage protection device.

[0041] In the adjustable load system compatible with three-phase, single-phase and DC, the dual-circuit low-voltage switch K2 is provided with an overvoltage protection device (not shown in the figure), wherein the overvoltage protection device is set to the highest voltage that the load impedance can withstand in the adjustable load system compatible with three-phase, single-phase and DC. When it is detected that the input side voltage exceeds the set low input voltage rating, the dual-circuit low-voltage switch K2 is prohibited from closing or tripping immediately after closing, thereby avoiding the double-circuit low-voltage switch K2 from closing by mistake when the input voltage is high, causing damage to the low-voltage side load. Furthermore, in the adjustable load system compatible with three-phase, single-phase and DC, an overcurrent fuse can be configured in the circuit where the parallel switch is located to prevent the parallel switch K3 and the dual-circuit high-voltage switch K4, or the parallel switch K3 and the three-phase input switch K1 from closing at the same time due to abnormal reasons, causing a direct short circuit of the input power supply.

[0042] In one embodiment, for any group of three-phase impedance loads, the minimum current of each impedance unit included in the three-phase impedance load is less than or equal to a preset minimum load current, wherein the preset minimum load current is determined based on the minimum input voltage; the sum of the total currents of all three-phase impedance loads is greater than or equal to a preset maximum load current, wherein the preset maximum load current is determined based on the maximum input voltage.

[0043] In one embodiment, a method for adjusting a load is provided, which is applied to Figure 1The adjustable load system shown is compatible with three-phase, single-phase and DC, and the method includes: controlling the three-phase input switch K1, the dual-way low-voltage input switch K2, the dual-way high-voltage input switch K4, the parallel phase switch K3 and the load throw-in / out switches corresponding to multiple groups of parallel three-phase impedance loads according to the input voltage of the adjustable load system compatible with three-phase, single-phase and DC, so that the load of the adjustable load system is within a preset value range, wherein the preset value range is determined according to the input voltage.

[0044] The adjustable load system compatible with three-phase, single-phase and DC can be connected to different power supply devices to be tested. According to the input voltage provided by the power supply device to be tested, the three-phase input switch K1, the dual-channel low-voltage input switch K2, the dual-channel high-voltage input switch K4, the parallel phase switch K3 and the load throw-in / out switches corresponding to multiple groups of parallel three-phase impedance loads are controlled to make the load of the adjustable load system within the preset value range corresponding to the input voltage, thereby determining the load capacity of the power supply device corresponding to the input voltage.

[0045] In one embodiment, the method includes: when the input voltage is the voltage provided by the three-phase power supply device, controlling the three-phase input switch to close, and the dual-way low-voltage input switch, the dual-way high-voltage input switch and the parallel-phase switch to open; controlling multiple load throw-in switches included in multiple groups of parallel three-phase impedance loads to adjust the first load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the first load current reaches the first preset load current corresponding to the three-phase power supply device.

[0046] like Figure 1 The adjustable load system shown, which is compatible with three-phase, single-phase and DC, can control the three-phase input switch K1 to close, the dual-way low-voltage input switch K2, the dual-way high-voltage input switch K4 and the parallel-phase switch K3 to open when the input voltage is the voltage provided by the three-phase power supply equipment. It can control multiple load insertion and withdrawal switches included in multiple groups of parallel storage box impedance loads to adjust the first load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the first load current reaches the first preset load current corresponding to the three-phase power supply equipment.

[0047] For example Figure 2 The adjustable load system compatible with three-phase, single-phase and DC shown schematically shows the operating status diagram of each switch in the adjustable load system compatible with three-phase, single-phase and DC when the input voltage is the voltage provided by the three-phase power supply equipment, the three-phase input switch K1 is controlled to be closed, and the load throw-in / out switches K11, K12, and K13 included in the three-phase impedance load R1 are controlled to be closed, K12a and K13c are closed, and K12b and K12c are disconnected to form a three-phase unbalanced load.

[0048] In one embodiment, the method includes: when the input voltage is the voltage provided by the single-phase power supply device, obtaining the input voltage of the single-phase power supply device; when the input voltage is lower than the rated phase voltage of the load resistor of the adjustable load system compatible with three-phase, single-phase and DC, controlling the dual-way low-voltage input switch and the parallel-phase switch to close, and the three-phase input switch and the dual-way high-voltage input switch to open; controlling the multiple load throw-in switches included in the multiple groups of parallel three-phase impedance loads to adjust the second load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the second load current reaches the second preset load current corresponding to the single-phase power supply device; when the input voltage is higher than the rated phase voltage of the load resistor and lower than the preset multiple of the rated phase voltage of the load resistor, controlling the dual-way high-voltage input switch to close, and the dual-way low-voltage input switch, the parallel-phase switch and the three-phase input switch to open; controlling the multiple load throw-in switches included in the multiple groups of parallel three-phase impedance loads to adjust the third load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the third load current reaches the third preset load current corresponding to the single-phase power supply device.

[0049] In one embodiment, the method includes: when the input voltage is the voltage provided by the DC power supply device, obtaining the input voltage of the DC power supply device; when the input voltage is lower than the rated phase voltage of the load resistor of the adjustable load system compatible with three-phase, single-phase and DC, controlling the dual-way low-voltage input switch and the parallel-phase switch to close, and the three-phase input switch and the dual-way high-voltage input switch to open; controlling the multiple load throw-in switches included in the multiple groups of parallel three-phase impedance loads to adjust the fourth load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the fourth load current reaches the fourth preset load current corresponding to the DC power supply device; when the input voltage is higher than the rated phase voltage of the load resistor and lower than the preset multiple of the rated phase voltage of the load resistor, controlling the dual-way high-voltage input switch to close, and the dual-way low-voltage input switch, the parallel-phase switch and the three-phase input switch to open; controlling the multiple load throw-in switches included in the multiple groups of parallel three-phase impedance loads to adjust the fifth load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the fifth load current reaches the fifth preset load current corresponding to the DC power supply device.

[0050] When the input voltage is the voltage provided by a single-phase power supply device or when the input voltage is the voltage provided by a DC power supply device, the input voltage of the single-phase power supply device or the voltage of the DC power supply device can be obtained. When the input voltage is lower than the rated phase voltage of the load resistor of the adjustable load system compatible with three-phase, single-phase and DC, such as Figure 3 The adjustable load system compatible with three-phase, single-phase and DC shown in the figure can control the dual-channel low-voltage input switch K2 and the parallel-phase switch K3 to merge, the three-phase input switch K1 and the dual-channel high-voltage input switch K4 to disconnect, and control multiple groups of parallel three-phase impedance loads including multiple load throw-in and throw-out switches, such as Figure 3As shown, when the adjustable load system compatible with three-phase, single-phase and DC is at maximum load, the load throw-in / out switches K11, K12, K13, K12a, K12b, K12c and K13c can be closed to obtain the operating state of each switch unit in the adjustable load system compatible with three-phase, single-phase and DC at low input voltage and maximum load.

[0051] In the case where the input voltage is higher than the rated phase voltage of the load resistor and lower than the preset multiple of the rated phase voltage of the load resistor, for example, assuming that the preset multiple is set to two times, that is, the input voltage is higher than the rated phase voltage of the load resistor and lower than two times the rated phase voltage of the load resistor, Figure 4 The adjustable load system compatible with three-phase, single-phase and DC shown in the figure can control the dual-channel high-voltage input switch K4 to be closed, the dual-channel low-voltage input switch K2, the parallel-phase switch K3 and the three-phase input switch K1 to be disconnected, and can control multiple load throw-in and throw-out switches included in multiple groups of parallel three-phase impedance loads to adjust the fifth load current of the adjustable load system compatible with three-phase, single-phase and DC, for example Figure 4 As shown, the load throw-in / out switches K11, K12, K13, K12b, and K12c are controlled to be closed to obtain the operating state of each switch unit in the adjustable load system that is high in input voltage and compatible with three-phase, single-phase, and DC when carrying partial load.

[0052] The above technical solution is compatible with three-phase, single-phase and DC adjustable load systems. It is compatible with three-phase input, single-phase input, DC input, high voltage and high current or low voltage and low current and other working conditions. Under different input modes, roughly similar maximum output power can be obtained, thereby avoiding severe power drop and extremely low power utilization under certain working conditions, improving the utilization rate of power components, and helping to reduce the volume, weight and cost of the load system, thereby improving economy. When switching between different input modes, only a small number of switches need to be adjusted, which is convenient and quick, avoiding tedious wiring work and high efficiency. An anti-misoperation interlocking system is provided to prevent abnormal faults caused by operator misoperation from causing damage to the equipment.

[0053] In one embodiment, a practical test case is combined to explain the parameter configuration of the required load. The equipment to be tested by this load includes: a three-phase AC ice melting device with a rated output of 400V / 600A / 400kVA, a single-phase AC ice melting device with a rated output of 220V / 600A / 132kVA, a small DC ice melting device with a rated output of 80V / 500A / 40kW, and a pickup truck type DC ice melting device with a rated output of 600A / 500V / 300kW.

[0054] In order to meet the testing requirements of the above four types of equipment, the parameters of each component designed according to this application are:

[0055] The three-phase AC input switch is designed to be no less than the maximum three-phase load voltage and current to be tested. Here, the rated parameters are 630A / 400V low-voltage three-phase four-wire molded case circuit breakers;

[0056] The dual-channel high-voltage input switch is designed to be no less than the maximum possible input phase voltage or DC voltage, and its current carrying capacity is designed according to the maximum total load current to be tested. Here, a low-voltage molded case circuit breaker with a rated parameter of 0A / 600V is used.

[0057] The dual-channel low-voltage input switch is designed to be no less than the maximum possible input phase voltage or DC voltage, and its current carrying capacity is designed according to the maximum total load current to be tested. Here, a low-voltage molded case circuit breaker with a rated parameter of 0A / 600V is used.

[0058] The parallel-phase switch is designed according to the highest input three-phase line voltage or DC voltage that it can withstand, and its current-carrying capacity is designed according to the maximum total load current to be tested when the three phases are connected in parallel. Here, a three-phase low-voltage molded case circuit breaker with a rated parameter of 400A / 600V is taken.

[0059] The load impedance is divided into 7 groups, and each group of impedance adopts star connection between three phases. The impedance of each phase is considered to be 230V rated voltage and 120% overload of the highest voltage. The impedance parameters are designed according to the load power current of each branch when converted to the rated voltage of 230V, which is 6kW, 12kW, 12kW, 30kW, 60kW, 120kW, and 200kW. The corresponding load switches are marked as Kf1, Kf2, K3, Kf4, Kf5, Kf6, and Kf7. The total rated output power is 440kW when the input three-phase 4000V and each load switch is put into use. When the maximum fluctuation of the input voltage is 120%, the maximum load power of 633kW can be provided.

[0060] When testing a three-phase AC ice melting device with a rated output of 400V / 600A / 400kVA, the three-phase output port of the device under test is connected to the three-phase AC input port of the load system, the three-phase input switch K1 is closed, the dual-way high-voltage input switch K4, the parallel phase switch K3, and the dual-way low-voltage input switch K2 are disconnected; the phase control switches in each load impedance are closed at the same time, and the load current is adjusted to the expected value by opening and closing the load throw-in and throw-out switches of each load impedance. For example, in order to test the rated power of 400kW, 5 groups of loads of 12kW, 12kW, 60kW, 120kW, and 200kW can be put in to obtain a nominal load power of 404kW; or 5 groups of loads of 6kW, 12kW, 60kW, 120kW, and 200kW can be put in to obtain a nominal load power of 398kW. When testing three-phase unbalanced load, for example, when phase A is 50kW, phase B is kW, and phase C is 0kW, the three-phase load switches corresponding to the load resistances of 12kW, 30kW, 60kW, 120kW, and 200kW can be respectively turned on, but by turning off all the switches of phase A and the switch of phase C corresponding to the 120kW load among these five switches, the nominal power of each load can be obtained.

[0061] When testing a single-phase AC ice melting device with a rated output of 220V / 600A / 132kVA, the output live wire and neutral wire of the tested device are connected to the double-circuit input port of the load system respectively, the dual-way high-voltage input switch K4 and the three-phase input switch K1 are disconnected, and the phase switch K3 and the dual-way low-voltage input switch K2 are closed. The phase control switches in all 7 groups of load impedances are closed at the same time, and the load current is adjusted to the expected value by opening and closing the load throw-in and throw-out switches of each load impedance. For example, under 220V voltage, the load power corresponding to each group of impedances is 5.4kW, 10.9kW, 10.9kW, 27.2kW, 54.5kW, 108.9kW, and 181.6kW respectively. In order to obtain 132kW power under 220V input, 3 groups of loads Kf2, K3, and Kf6 can be put into the theoretically nominal 131kW load power. When the actual output power deviates from the expected value, the load power close to the required value can be obtained by fine-tuning the smaller load switch.

[0062] When testing a DC ice melting device with a rated output of 80V / 500A / 40kW, the output positive and negative poles of the device under test are connected to the double-circuit input port of the load system respectively, the dual-way high-voltage input switch K4 and the three-phase input switch K1 are disconnected, and the parallel-phase switch K3 and the dual-way low-voltage input switch K2 are closed. The phase control switches in all 7 groups of load impedances are closed at the same time, and the load current is adjusted to the expected value by opening and closing the load throw-in and throw-out switches of each load impedance. For example, under 220V voltage, the load power corresponding to each group of impedances is 0.7kW, 1.4kW, 1.4kW, 3.6kW, 7.2kW, 14.4kW, and 24.0kW, respectively, with a total power of 52.8kW. For example, in order to test the rated power of 80V / 500A / 40kW, three groups of loads, Kf2, Kf6, and Kf7, can be put into the theoretically nominal load power of 39.8kW. When the actual output power deviates from the expected value, the load power close to the required value can be obtained by fine-tuning the smaller load switch.

[0063] When testing a DC ice melting device with a rated output of 500V / 600A / 300kW, the output positive and negative poles of the tested device are connected to the double-circuit input port of the load system respectively, the dual-way high-voltage input switch K4 is closed, the three-phase input switch K1, the parallel phase switch K3, and the dual-way low-voltage input switch K2 are all disconnected, and the rated output DC voltage of 500V is applied to the bus voltage. Although it exceeds the rated voltage of each impedance 230V×2=460V, it has not exceeded its maximum voltage 230V×2*120%=520V. At this time, each device can withstand overload operation. For example, under a voltage of 500V, the load power corresponding to each group of impedances is 4.7kW, 9.4kW, 9.4kW, 18.8kW, 46.9kW, 93.8kW, and 156.3kW, respectively, with a total power of 343kW. The phase control switches in all 7 groups of load impedances are closed at the same time, and the load current is adjusted to the expected value by opening and closing the load throw-in and throw-out switches of each load impedance. For example, in order to test the rated power of 500V / 600A / 300kW, three groups of loads, Kf5, Kf6 and Kf7, can theoretically obtain the nominal load power of 297kW. When the actual output power deviates from the expected value, the load power close to the required value can be obtained by fine-tuning the smaller load switch.

[0064] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware.

[0065] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0066] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. An adjustable load system compatible with three-phase, single-phase and DC, characterized in that: The adjustable load system compatible with three-phase, single-phase and DC includes: A three-phase input switch, wherein the input side of the three-phase input switch is connected to a three-phase AC input port, each item on the output side of the three-phase input switch is respectively connected to a three-phase voltage bus, and the neutral line of the three-phase input switch is connected to the neutral bus; A dual-way low-voltage input switch, wherein the input side of the dual-way low-voltage input switch is respectively connected to the positive electrode and the negative electrode of the DC input port, and the output side of the dual-way low-voltage output switch is connected to the input port of the parallel-phase switch and the zero bus; The parallel-phase switch, the output end of the parallel-phase switch includes three ports, and the output ends of the parallel-phase switch are all connected to the three-phase voltage bus; a dual-way high-voltage input switch, wherein the input side of the dual-way high-voltage input switch is connected in parallel with the input side of the dual-way low-voltage input switch, and the output side T of the dual-way high-voltage input switch is connected to any two phases of the three-phase voltage bus; and A plurality of groups of three-phase impedance loads are connected in parallel, each group of three-phase impedance loads comprises a three-phase symmetrical impedance unit connected in star, the input side of the three-phase impedance loads is connected to a load throw-in / out switch and is connected to the three-phase voltage bus, and the common point of the three-phase impedance loads connected in star is connected to the zero bus.

2. The adjustable load system compatible with three-phase, single-phase and DC according to claim 1, characterized in that: The adjustable load system compatible with three-phase, single-phase and DC also includes: The dual-way low-voltage input switch, the input side of the dual-way low-voltage input switch is respectively connected to the neutral line and the live line of the unidirectional input port, and the output side of the dual-way low-voltage output switch is connected to the input port of the parallel-phase switch and the neutral bus.

3. The adjustable load system compatible with three-phase, single-phase and DC according to claim 1, characterized in that: An interlocking circuit is provided between the dual-way high-voltage switch and the dual-way low-voltage switch to prohibit the dual-way high-voltage switch and the dual-way low-voltage switch from being closed at the same time; An interlocking circuit is provided between the dual-circuit high-voltage switch and the three-phase input switch to prohibit the dual-circuit high-voltage switch and the three-phase input switch from being closed simultaneously; An interlocking circuit is provided between the dual-way low-voltage switch and the three-phase input switch to prohibit the dual-way low-voltage switch and the three-phase input switch from being closed at the same time; An interlocking circuit is provided between the three-phase input switch and the parallel-phase switch to prohibit the three-phase input switch and the parallel-phase switch from being closed at the same time; An interlocking circuit is provided between the dual-channel high-voltage input switch and the parallel-phase switch to prohibit the dual-channel high-voltage input switch and the parallel-phase switch from being closed at the same time.

4. The adjustable load system compatible with three-phase, single-phase and DC according to claim 1, characterized in that: The load throw-in / out switch comprises a linkage load throw-in / out switch and a phase-splitting load throw-in / out switch. The load of the adjustable load system compatible with three-phase, single-phase and DC is adjusted by controlling the linkage load throw-in / out switch and / or the phase-splitting load throw-in / out switch.

5. The adjustable load system compatible with three-phase, single-phase and DC according to claim 1, characterized in that: The dual-circuit low-voltage switch includes an overvoltage protection device.

6. The adjustable load system compatible with three-phase, single-phase and DC according to claim 1, characterized in that: For any group of three-phase impedance loads, the minimum current of each impedance unit included in the three-phase impedance load is less than or equal to a preset minimum load current, wherein the preset minimum load current is determined according to the minimum input voltage; The sum of the total currents of all three-phase impedance loads is greater than or equal to a preset maximum load current, wherein the preset maximum load current is determined according to the maximum input voltage.

7. A method for regulating a load, characterized in that: Applied to the adjustable load system compatible with three-phase, single-phase and direct current as claimed in any one of claims 1 to 6, the method comprises: According to the input voltage of the adjustable load system compatible with three-phase, single-phase and DC, the three-phase input switch, the dual-channel low-voltage input switch, the dual-channel high-voltage input switch, the parallel-phase switch and the load throw-in / out switches corresponding to multiple groups of parallel three-phase impedance loads are controlled so that the load of the adjustable load system is within a preset value range, wherein the preset value range is determined according to the input voltage.

8. The method for adjusting a load according to claim 7, characterized in that: The method comprises: When the input voltage is the voltage provided by the three-phase power supply device, the three-phase input switch is controlled to be closed, and the dual-channel low-voltage input switch, the dual-channel high-voltage input switch and the parallel-phase switch are disconnected; Control multiple load throw-in / out switches included in multiple groups of parallel three-phase impedance loads to adjust the first load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the first load current reaches a first preset load current corresponding to the three-phase power supply device.

9. The method for adjusting a load according to claim 7, characterized in that: The method comprises: When the input voltage is a voltage provided by a single-phase power supply device, obtaining the input voltage of the single-phase power supply device; When the input voltage is lower than the rated phase voltage of the load resistor of the adjustable load system compatible with three-phase, single-phase and DC, the dual-channel low-voltage input switch and the parallel-phase switch are controlled to be closed, and the three-phase input switch and the dual-channel high-voltage input switch are disconnected; Controlling a plurality of load throw-in / out switches included in a plurality of groups of three-phase impedance loads connected in parallel to adjust a second load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the second load current reaches a second preset load current corresponding to the single-phase power supply device; When the input voltage is higher than the rated phase voltage of the load resistor and lower than a preset multiple of the rated phase voltage of the load resistor, the dual-channel high-voltage input switch is controlled to be closed, and the dual-channel low-voltage input switch, the parallel-phase switch and the three-phase input switch are disconnected; Control multiple load throw-in / out switches included in multiple groups of parallel three-phase impedance loads to adjust the third load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the third load current reaches a third preset load current corresponding to the single-phase power supply device.

10. The method for adjusting a load according to claim 7, characterized in that: The method comprises: In a case where the input voltage is a voltage provided by a DC power supply device, obtaining an input voltage of the DC power supply device; When the input voltage is lower than the rated phase voltage of the load resistor of the adjustable load system compatible with three-phase, single-phase and DC, the dual-channel low-voltage input switch and the parallel-phase switch are controlled to be closed, and the three-phase input switch and the dual-channel high-voltage input switch are disconnected; Controlling a plurality of load throw-in / out switches included in a plurality of groups of three-phase impedance loads connected in parallel to adjust a fourth load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the fourth load current reaches a fourth preset load current corresponding to the DC power supply device; When the input voltage is higher than the rated phase voltage of the load resistor and lower than a preset multiple of the rated phase voltage of the load resistor, the dual-channel high-voltage input switch is controlled to be closed, and the dual-channel low-voltage input switch, the parallel-phase switch and the three-phase input switch are disconnected; Control multiple load throw-in / out switches included in multiple groups of parallel three-phase impedance loads to adjust the fifth load current of the adjustable load system compatible with three-phase, single-phase and DC, so that the fifth load current reaches the fifth preset load current corresponding to the DC power supply device.

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