A constant current source device for temperature rise test of AC and DC complete switch cabinet

Abstract

The present invention discloses a constant current source device for temperature rise test of AC / DC complete switch cabinet, comprising a sequentially connected slow start circuit, an input isolation transformer, a rectifier, a power electronic power converter, a filter and an AC / DC output switching control unit; the constant current source device also comprises a control module, if the control module is configured as an AC mode, the power electronic power converter is configured to convert DC to AC, and the filter and AC / DC output switching control unit is configured to filter the AC signal to adapt the output end to connect to the AC complete switch cabinet; if the control module is configured as a DC mode, the power electronic power converter is configured to convert DC to DC, and the filter and AC / DC output switching control unit is configured to filter the DC signal to adapt the output end to connect to the DC complete switch cabinet. The constant current source device of the present invention can simultaneously meet the test requirements of AC complete switch equipment and DC complete switch equipment.

Description

Technical Field

[0001] The invention relates to the technical field of temperature rise testing, and in particular to a constant current source device for temperature rise testing of an AC / DC complete switch cabinet. Background Art

[0002] The temperature rise generated during the operation of AC complete switchgear and DC complete switchgear has a direct impact on the safety and reliability of the switchgear and power supply system. Therefore, the temperature rise test in the national standards GB7251-2013 and GB25890 is a crucial test item for switchgear. According to the standard, the temperature rise test involves the temperature rise of the entire equipment itself, as well as the temperature rise of each function, main bus and distribution bus.

[0003] Existing AC high current generating devices for temperature rise testing of complete switchgear generally use a multi-magnetic circuit transformer to convert the mains power into a low-voltage, high-current output power supply, which is connected to the input end of the low-voltage complete switchgear. Variable resistors or current regulators are connected to each branch feeder of the device under test as adjustable loads to obtain adjustable test currents for temperature rise testing.

[0004] Since the entire system is large in size, the test current will also change due to grid voltage fluctuations and changes in the resistance of related components in the current-carrying circuit, requiring operators to frequently adjust and intervene. The adjustment accuracy of the output current is generally greater than 3%. At the same time, there is also the problem of excessive inductive reactive power at the input end, which affects the quality of the grid and causes energy waste.

[0005] Theoretically, the higher the output current accuracy and the better the stability of the current generating device that provides current to the complete switchgear, the more accurate the test results of the temperature rise test of the complete switchgear will be.

[0006] The prior art lacks an ideal high-precision and high-stability current generating device for temperature rise testing of complete switchgear. Summary of the invention

[0007] In order to solve the problems of the prior art, the present invention provides a constant current source device for temperature rise testing of AC and DC complete switch cabinets, which not only has high output current accuracy and good stability, but also can flexibly configure AC mode and DC mode to meet different types of test requirements. The technical solution is as follows:

[0008] The present invention provides a constant current source device for temperature rise test of AC / DC complete switch cabinet, which is used to provide current for temperature rise test for AC complete switch cabinet and / or DC complete switch cabinet. The constant current source device comprises:

[0009] A slow-start circuit, the input end of which is electrically connected to an AC power source outside the device through a connector, so that its output voltage rises slowly when the connector is connected to the external AC power;

[0010] An input isolation transformer, whose input side is electrically connected to the output side of the slow-start circuit, so as to output the input voltage after voltage conversion, and the input side and output side of the input isolation transformer are isolated from each other;

[0011] A plurality of constant current branches, the number of the constant current branches is more than three, the input end of each constant current branch is connected to the output side of the input isolation transformer, and the output end of each constant current branch is configured to be connected to a complete set of switch cabinets; each constant current branch includes:

[0012] a rectifier, whose input end is connected to the output side of the input isolation transformer, and which is configured to convert the received alternating current into direct current;

[0013] a power electronic power converter, whose input is connected to the output of the rectifier and is configured to perform power conversion;

[0014] A filtering and AC / DC output switching control unit, whose input end is connected to the output end of the power electronic power converter, and which is configured to filter the received signal;

[0015] The constant current source device further includes a control module, which is electrically connected to the power electronic power converter and the filter and AC / DC output switching control unit, and is configured to control the working states of the power electronic power converter and the filter and AC / DC output switching control unit, including:

[0016] If the control module is configured in AC mode, the working state of the power electronic power converter is to convert DC into AC, and the working state of the filtering and AC / DC output switching control unit is to filter the AC signal to adapt the output end of the constant current branch to connect to the AC complete switch cabinet;

[0017] If the control module is configured in DC mode, the working state of the power electronic power converter is to convert DC into DC, and the working state of the filtering and AC / DC output switching control unit is to filter the DC signal to adapt the output end of the constant current branch to connect to the DC switch cabinet.

[0018] Further, the power electronic power converter includes a power switch device, and the control module is configured to set a target current and perform closed-loop PI control according to the set value of the target current, including: calculating an output PWM wave to control the on / off or opening size of the power switch device of the power electronic power converter;

[0019] The control module is configured to independently control the output current of the output end of each constant current branch, and the current error rate of the output current after filtering by the filtering and AC / DC output switching control unit is less than 2% compared with the set value of the target current.

[0020] Furthermore, the power switch device is an IGBT or a MOSFET, and the current error rate of the output current after filtering by the filtering and AC / DC output switching control unit is less than 1% compared with the set value of the target current.

[0021] Further, when the output end of the constant current branch is connected to an AC complete switch cabinet, the control module is configured to select a three-phase output mode or a single-phase output mode;

[0022] If the control module selects the three-phase output mode, the output ends of the three constant current branches are respectively the output live wire, the output neutral wire and the output ground wire, wherein the output ground wire is grounded, the output live wire is connected to the output three-phase live wire phase end of the AC complete switch cabinet, and the output neutral wire is short-connected to the input three-phase live wire short-connection point of the AC complete switch cabinet, or the output ends of multiple constant current branches are connected in parallel to an output distribution bus;

[0023] If the control module selects the single-phase output mode, the output end of a single constant current branch is connected to the output end of the AC complete switch cabinet, or the output ends of multiple constant current branches are connected in parallel to the output end of the AC complete switch cabinet.

[0024] Furthermore, when the output end of the constant current branch is connected to a DC complete switch cabinet, the control module is configured as a DC mode, and the output end of each constant current branch is respectively connected to the output end of the DC complete switch cabinet, or the output ends of multiple constant current branches are connected in parallel to the output end of the DC complete switch cabinet.

[0025] Further, a single set of constant current source devices is configured with six, eight or nine constant current branches.

[0026] Furthermore, a plurality of constant current source devices are configured to operate in parallel to provide output current to a complete set of switch cabinets.

[0027] Furthermore, the input end of the slow-start circuit is connected to the AC mains, and the power output end of the constant current branch is configured with an output terminal or a copper busbar.

[0028] Furthermore, the control module includes a main control unit and a power conversion control interface unit electrically connected to each other, wherein:

[0029] The power conversion control interface unit is electrically connected to the power electronic power converter of each constant current branch, and is configured to control the working state of the power electronic power converter to convert direct current into alternating current, or to convert direct current into direct current;

[0030] The main control unit is electrically connected to the filtering and AC / DC output switching control units of each constant current branch, and is configured to control the working state of the filtering and AC / DC output switching control units to filter AC signals or filter DC signals.

[0031] Furthermore, the control module also includes a measuring unit and a human-machine interface, wherein:

[0032] The measuring unit is electrically connected to the main control unit and is configured to sample the output current and / or output voltage of each constant current branch;

[0033] The human-machine interface is electrically connected to the main control unit via a communication unit, and is configured to display test data of a complete set of switch cabinet temperature rise tests.

[0034] The beneficial effects brought by the technical solution provided by the present invention are as follows:

[0035] a. Using a set of AC and DC dual-purpose constant current source device can simultaneously meet the testing requirements of AC complete switchgear and DC complete switchgear, reducing the configuration cost of the complete switchgear test device;

[0036] b. The constant current source device of the power electronic power converter has high output current accuracy and good stability, which improves the test result accuracy of the temperature rise test of the complete set of switchgear. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of the circuit structure of a constant current source device for temperature rise testing of an AC / DC complete switch cabinet provided as an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "including" and "having" and any variations thereof in the description and claims of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, products or equipment.

[0041] In the prior art, for the testing of AC complete switchgear and DC complete switchgear, two different test systems need to be configured, each with a current generator. One of the concepts of the present invention is to provide a constant current source device with high configuration flexibility, which can simultaneously meet the testing requirements of AC complete switchgear and DC complete switchgear, and output AC or DC to the complete equipment for temperature rise test in the occasions where high output accuracy is required.

[0042] In one embodiment of the present invention, a constant current source device for temperature rise testing of an AC / DC complete switch cabinet is provided, which is used to provide a current for temperature rise testing for an AC complete switch cabinet and / or a DC complete switch cabinet. The constant current source device of this embodiment can simultaneously meet the testing requirements of an AC complete switch cabinet and a DC complete switch cabinet, such as Figure 1 As shown, the constant current source device includes the following circuit modules connected in sequence:

[0043] The input end of the slow-start circuit is electrically connected to an AC power source outside the device (such as 220V AC mains) through a connector, so that its output voltage rises slowly when the connector is connected to the external AC power. The slow-start circuit is used to reduce the impact of the inrush current on the circuit. Common methods include series inductance, series resistance, series NTC resistance, etc.

[0044] An input isolation transformer, whose input side is electrically connected to the output side of the slow-start circuit, so as to output the input voltage after voltage conversion, and the input side and output side of the input isolation transformer are isolated from each other;

[0045] A plurality of constant current branches, the number of the constant current branches is more than three, the input end of each constant current branch is connected to the output side of the input isolation transformer, and the power output end of each constant current branch is configured with an output terminal or copper busbar for connecting to a complete set of switch cabinets; each constant current branch includes:

[0046] The rectifier, whose input end is connected to the output side of the input isolation transformer, is configured to convert the received alternating current into direct current.

[0047] A power electronic power converter, whose input end is connected to the output end of the rectifier, is configured to perform power conversion; specifically, the power electronic power converter includes a power switching device, such as an IGBT or a MOSFET, and the power electronic power converter includes a DC / DC converter and a DC / AC converter.

[0048] A filtering and AC / DC output switching control unit, whose input end is connected to the output end of the power electronic power converter, is configured to filter the received signal, and whose output end is connected to the switch cabinet device under test through the output terminal or busbar; specifically, the filtering and AC / DC output switching control unit includes a DC filter and an AC filter.

[0049] The above are the main components of the current generator. When a DC / DC converter and a DC filter are selected to access the circuit, a DC current generator is formed. When a DC / AC converter and an AC filter are selected to access the circuit, an AC current generator is formed.

[0050] The constant current source device further includes a control module, which is electrically connected to the power electronic power converter, the filter and the AC / DC output switching control unit, and is configured to control the working state of the power electronic power converter and the filter and the AC / DC output switching control unit. During the test, a reverse power transmission mode is adopted, that is, the output current of the constant current source is connected from the power distribution output end of the switch cabinet, and the main bus input end of the switch cabinet is short-circuited, and:

[0051] If the control module is configured in AC mode, a DC / AC converter is selected to access the circuit so that the converter works to convert DC into AC, and an AC filter is selected to access the circuit so that the filter and AC / DC output switching control unit works to filter the AC signal, so as to adapt the output end to be connected to an AC switch cabinet;

[0052] If the control module is configured in DC mode, a DC / DC converter access circuit is selected to make the converter work in the state of converting DC into DC, and a DC filter access circuit is selected to make the filtering and AC / DC output switching control unit work in the state of filtering the DC signal to adapt the output end to be connected to a DC complete switch cabinet.

[0053] The applicable modes of different types of complete switchgear are described below:

[0054] When the output end is connected to an AC complete switch cabinet, the control module is configured to select a three-phase output mode or a single-phase output mode;

[0055] If the control module selects the three-phase output mode, the output ends of the three constant current branches are respectively the output live wire, the output neutral wire and the output ground wire, wherein the output ground wire is grounded, the output live wire is connected to the output three-phase live wire phase end of the AC complete switch cabinet, the output neutral wire is short-connected to the input three-phase live wire short-connection point of the AC complete switch cabinet, and the three-phase phase difference is 120°, or the output ends of multiple constant current branches are connected in parallel to an output distribution bus;

[0056] If the control module selects the single-phase output mode, the output end of a single constant current branch is connected to the output end of the AC complete switch cabinet, or the output ends of multiple constant current branches are connected in parallel to the output end of the AC complete switch cabinet.

[0057] When the output end is connected to a DC switch cabinet, the control module is configured in DC mode, and the output ends of each constant current branch are respectively connected to the output end of the DC switch cabinet, or the output ends of multiple constant current branches are connected in parallel to the output end of the DC switch cabinet.

[0058] The control module is configured to set a target current. After the mode is set, the control module performs closed-loop PI control according to the set value of the target current, including: calculating an output PWM wave to control the on / off or opening size of the power switch device of the power electronic power converter; the control module is configured to independently control the output current of the output end of each constant current branch, and realizes high precision and high stability of the output current of the constant current source device through closed-loop PI control automatic adjustment. The current output after filtering by the filtering and AC / DC output switching control unit is compared with the set value of the target current, and the current error rate flowing through a single channel or a summary main bus is less than 1%, that is, the absolute value of the difference between the actual output current and the set value of the target current is less than 1% of the set value of the target current, and is not affected by the fluctuation of the main power supply, the impedance change of the components in the switch cabinet, and the change of the wiring form in the switch cabinet, thereby enhancing the flexibility and high efficiency of the temperature rise test process.

[0059] This embodiment adopts the form of power electronic power converter, which has high current stabilization accuracy, fast dynamic response, and can output in multiple channels flexibly. Figure 1 For example, a single set of constant current source device is configured with six constant current branches. Since each constant current branch can be controlled independently, for example Figure 1 The three terminals "Output 1" to "Output 3" can be connected to a three-phase AC switch cabinet. Figure 1 The "Output 4", "Output 5" and "Output 6" terminals can be connected in parallel to the single-phase output of the AC switch cabinet, or they can be configured into 6 single-phase outputs or 2 three-phase outputs. It is flexible and does not require secondary wiring.

[0060] When the parallel output current of all constant current branches of a set of constant current source devices cannot meet the needs of a large-capacity switch cabinet, multiple sets of constant current source devices can be operated in parallel to provide output current to a complete set of switch cabinet, further enhancing the current output capacity during testing and improving the flexibility of the test device configuration.

[0061] like Figure 1 As shown, the control module includes a main control unit and a power conversion control interface unit, a measuring unit, and a communication unit electrically connected to the main control unit, wherein the communication unit is used to connect to a human-machine interface, such as an HMI human-machine interface.

[0062] The power conversion control interface unit is electrically connected to the converter of each constant current branch, and is configured to issue instructions to the converter to control the working state of the converter to convert direct current into alternating current, or to convert direct current into direct current;

[0063] The main control unit is electrically connected to the filtering and AC / DC output switching control units of each constant current branch, and is configured to send instructions thereto to control the working state of the filtering and AC / DC output switching control unit to filter AC signals or filter DC signals.

[0064] The measuring unit is electrically connected to the main control unit and is configured to sample the output current and / or output voltage of each constant current branch;

[0065] The human-machine interface is electrically connected to the main control unit via a communication unit, and is configured to display test data of a complete set of switch cabinet temperature rise tests.

[0066] In this embodiment, the control module can control the working state of the power electronic power converter and the filter and AC / DC output switching control unit by manual setting, such as setting a control button on the device, or setting a control button on the human-machine interface to manually set the AC mode or DC mode. If the AC mode button is pressed / the AC mode button is clicked, the power electronic power converter works in the DC / AC working mode, and the AC filter is connected to the circuit; if the DC mode button is pressed / the DC mode button is clicked, the power electronic power converter works in the DC / DC working mode, and the DC filter is connected to the circuit. This is like operating the air volume level button on an electric fan, which can control different output power modes of the electric fan motor, and the mode control can be achieved through the circuit, without involving the improvement of the computer program.

[0067] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0068] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A constant current source device for temperature rise testing of AC and DC complete switch cabinets, characterized in that: Used to provide current for temperature rise test for AC complete switchgear and DC complete switchgear, the constant current source device includes: A slow-start circuit, the input end of which is electrically connected to an AC power source outside the device through a connector; An input isolation transformer, whose input side is electrically connected to the output side of the slow-start circuit, so as to convert the input voltage and output it, and the input side and the output side of the input isolation transformer are isolated from each other; A plurality of constant current branches, the number of the constant current branches is more than three, the input end of each constant current branch is connected to the output side of the input isolation transformer, and the output end of each constant current branch is configured to be connected to a complete set of switch cabinets; each constant current branch includes: a rectifier, whose input end is connected to the output side of the input isolation transformer, and which is configured to convert the received alternating current into direct current; a power electronic power converter, whose input is connected to the output of the rectifier and is configured to perform power conversion; A filtering and AC / DC output switching control unit, whose input end is connected to the output end of the power electronic power converter, and which is configured to filter the received signal; The constant current source device further includes a control module, which is electrically connected to the power electronic power converter and the filter and AC / DC output switching control unit, and is configured to control the working states of the power electronic power converter and the filter and AC / DC output switching control unit, including: If the control module is configured in AC mode, the working state of the power electronic power converter is to convert DC into AC, and the working state of the filtering and AC / DC output switching control unit is to filter the AC signal to adapt the output end of the constant current branch to connect to the AC complete switch cabinet; If the control module is configured in DC mode, the working state of the power electronic power converter is to convert DC into DC, and the working state of the filtering and AC / DC output switching control unit is to filter the DC signal to adapt the output end of the constant current branch to connect to the DC switch cabinet.

2. The constant current source device according to claim 1, characterized in that: The power electronic power converter includes a power switch device, and the control module is configured to set a target current and perform closed-loop PI control according to the set value of the target current, including: calculating an output PWM wave to control the on / off or opening size of the power switch device of the power electronic power converter; The control module is configured to independently control the output current of the output end of each constant current branch, and the current error rate of the output current after filtering by the filtering and AC / DC output switching control unit is less than 2% compared with the set value of the target current.

3. The constant current source device according to claim 2, characterized in that: The power switch device is an IGBT or a MOSFET. The current error rate of the output current after filtering by the filtering and AC / DC output switching control unit is less than 1% compared with the set value of the target current.

4. The constant current source device according to claim 1, characterized in that: When the output end of the constant current branch is connected to the AC complete switch cabinet, the control module is configured to select a three-phase output mode or a single-phase output mode; If the control module selects the three-phase output mode, the output ends of the three constant current branches are respectively the output live wire, the output neutral wire and the output ground wire, wherein the output ground wire is grounded, the output live wire is connected to the output three-phase live wire phase end of the AC complete switch cabinet, and the output neutral wire is short-connected to the input three-phase live wire short-connection point of the AC complete switch cabinet, or the output ends of multiple constant current branches are connected in parallel to an output distribution bus; If the control module selects the single-phase output mode, the output end of a single constant current branch is connected to the output end of the AC complete switch cabinet, or the output ends of multiple constant current branches are connected in parallel to the output end of the AC complete switch cabinet.

5. The constant current source device according to claim 1, characterized in that: When the output end of the constant current branch is connected to the DC complete switch cabinet, the control module is configured in DC mode, and the output end of each constant current branch is respectively connected to the output end of the DC complete switch cabinet, or the output ends of multiple constant current branches are connected in parallel to the output end of the DC complete switch cabinet.

6. The constant current source device according to claim 1, characterized in that: A single constant current source device is configured with six, eight or nine constant current branches.

7. The constant current source device according to claim 1, characterized in that: A plurality of constant current source devices are configured to operate in parallel to provide output current to a complete switch cabinet.

8. The constant current source device according to claim 1, characterized in that: The input end of the slow-start circuit is connected to the AC mains, and the power output end of the constant current branch is configured with an output terminal or a copper busbar.

9. The constant current source device according to claim 1, characterized in that: The control module includes a main control unit and a power conversion control interface unit electrically connected to each other, wherein: The power conversion control interface unit is electrically connected to the power electronic power converter of each constant current branch, and is configured to control the working state of the power electronic power converter to convert direct current into alternating current, or to convert direct current into direct current; The main control unit is electrically connected to the filtering and AC / DC output switching control units of each constant current branch, and is configured to control the working state of the filtering and AC / DC output switching control units to filter AC signals or filter DC signals.

10. The constant current source device according to claim 9, characterized in that: The control module also includes a measuring unit and a human-machine interface, wherein: The measuring unit is electrically connected to the main control unit and is configured to sample the output current and / or output voltage of each constant current branch; The human-machine interface is electrically connected to the main control unit via a communication unit, and is configured to display test data of a complete set of switch cabinet temperature rise tests.

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