Multi-path isolation pressurization circuit and method and multi-path isolation pressurization testing device and method

Abstract

The invention discloses a multi-path isolation pressurization circuit and method and a multi-path isolation pressurization testing device and method.According to the multi-path isolation pressurization testing device and method, a plurality of charging branches which are connected in parallel are adopted to charge a plurality of flexible direct current converter valve sub-modules, the charging efficiency is improved, and isolation circuits are arranged in the charging branches, so that the charging efficiency is improved; and the clamping resistor is connected between the negative output ends of the adjacent charging branches, so that the mutual influence between the adjacent series sub-modules is effectively prevented, a connecting copper bar between the sub-modules does not need to be removed, and the charging efficiency is further improved.

Description

Technical Field

[0001] The invention relates to a multi-channel isolation pressurization circuit and method, a multi-channel isolation pressurization testing device and method, and belongs to the field of testing of flexible DC converter valves. Background Art

[0002] The submodule is the core device of the flexible DC converter valve. A set of MMC flexible DC converter valves is composed of thousands of submodules (i.e. power modules) in cascade. When the converter valve is overhauled, the function of each submodule needs to be tested, which requires charging each submodule to complete the functional test. At present, the traditional multi-channel isolation pressure circuit can only charge a single submodule at a time, which has the disadvantage of low charging efficiency and cannot meet the urgent needs of on-site operation and maintenance personnel to improve test efficiency. Summary of the invention

[0003] The present invention provides a multi-channel isolation pressure-applying circuit and method, and a multi-channel isolation pressure-applying testing device and method, which solve the problems disclosed in the background technology.

[0004] According to one aspect of the present disclosure, a multi-channel isolation and boosting circuit is provided, comprising a plurality of parallel charging branches, wherein the input end of the charging branch inputs external alternating current, and the output end of the charging branch is externally connected to the input end of a flexible DC converter valve submodule; the charging branch comprises an isolation circuit and a rectifier current limiting circuit connected in series in sequence from the input end to the output end; and an embedded resistor is connected between the negative output ends of adjacent charging branches.

[0005] In some embodiments of the present disclosure, the rectifier current limiting circuit includes a primary coil, a primary capacitor, a field effect transistor, a secondary capacitor string and a sampling resistor; The first end and the second end of the primary capacitor are respectively used as input ends of the rectifier current limiting circuit, the first end of the primary capacitor is connected to the opposite end of the primary coil, the same end of the primary coil is connected to the drain of the field effect tube, and the source of the field effect tube is connected to the second end of the primary capacitor; A first end of the secondary capacitor string is connected to one end of the sampling resistor, the other end of the sampling resistor serves as an output end of the rectifier current limiting circuit, and a second end of the secondary capacitor string serves as another output end of the rectifier current limiting circuit; In the secondary capacitor string, each secondary capacitor is connected in parallel with the same structure, which includes a diode and a secondary coil, the cathode of the diode is connected to the first end of the secondary capacitor, the same-name end of the secondary coil is connected to the anode of the diode, the opposite-name end of the secondary coil is connected to the second end of the secondary capacitor, and the secondary coil and the primary coil form a transformer structure.

[0006] In some embodiments of the present disclosure, external AC power is input to the input ends of all charging branches through a controllable main switch.

[0007] In some embodiments of the present disclosure, a controllable sub-switch is further connected in series in the charging branch.

[0008] In some embodiments of the present disclosure, the controllable sub-switch is connected in series upstream of the isolation circuit.

[0009] According to another aspect of the present disclosure, a multi-channel isolation and pressure-increasing method is provided, which uses the multi-channel isolation and pressure-increasing circuit to charge a plurality of flexible DC converter valve submodules connected in series.

[0010] According to another aspect of the present disclosure, a multi-channel isolation pressure test device is provided, comprising the multi-channel isolation pressure circuit described above.

[0011] According to another aspect of the present disclosure, a multi-channel isolation pressure test method is provided, comprising: The above-mentioned multi-channel isolation and pressure boosting circuit is used to charge a plurality of series-connected flexible DC converter valve submodules; Perform functional test on the submodules that have completed charging.

[0012] The beneficial effects achieved by the present invention are as follows: the present invention uses multiple parallel charging branches to charge multiple flexible DC converter valve submodules to improve the charging efficiency, and an isolation circuit is provided in the charging branch, and a clamping resistor is connected between the negative output ends of adjacent charging branches to effectively prevent adjacent series submodules from affecting each other. There is no need to remove the connecting copper busbars between the submodules, thereby further improving the charging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The circuit diagram of the multi-channel isolation pressure-boosting circuit; Figure 2 is a circuit diagram of a rectifier current limiting circuit; Figure 3 It is a schematic diagram of a multi-channel isolation pressure test device; Figure 4 This is the circuit diagram of the circuit connected to the input terminal of the IO board. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. It is obvious that the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0015] Unless otherwise specified, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0016] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0017] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0018] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0019] It should be noted that similar symbols and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

[0020] In order to solve the problem of low charging efficiency of existing multi-channel isolation and pressure-boosting circuits, the present disclosure proposes a multi-channel isolation and pressure-boosting circuit and method, and a multi-channel isolation and pressure-boosting testing device and method.

[0021] Figure 1 This is a schematic diagram of an embodiment of the multi-channel isolation and boosting circuit disclosed in the present invention, including multiple parallel charging branches, the input end of the charging branch inputs external AC power, and the output end of the charging branch is externally connected to the input end of the flexible DC converter valve submodule; the charging branch includes an isolation circuit and a rectifier current limiting circuit connected in series from the input end to the output end; a clamping resistor is connected between the negative output ends of adjacent charging branches.

[0022] It should be noted that the number of charging branches can be adjusted according to the number of sub-modules to be charged, and the input is alternating current and the output is direct current.

[0023] To facilitate charging control, in some embodiments, the input ends of all charging branches input external AC power through a controllable main switch. At the same time, controllable sub-switches can also be connected in series in the charging branches, specifically in series upstream of the isolation circuit. These controllable switches can be thyristors or IGBTs.

[0024] It should be noted that the isolation circuit is isolated through the coil. The isolation circuit can disconnect the electrical connection between the sub-module and the input power supply to ensure the safety of the tester and the sub-module. At the same time, the cooperation of the isolation circuit and the clamping resistor can avoid the mutual influence between the two adjacent sub-modules during the sub-module IGBT unlocking test (because the sub-modules are in series, the ground potential of each sub-module will fluctuate during the IGBT unlocking test, resulting in mutual influence between the two adjacent sub-modules).

[0025] It should be noted that the rectifier current limiting circuit inputs AC power and outputs DC power, which can control the unidirectional charging of the sub-module capacitor and play a role in limiting the impact current.

[0026] In some embodiments, Figure 2 As shown, the rectifier current limiting circuit includes a primary coil S1, a primary capacitor C1, a field effect tube M1, a secondary capacitor C2 string and a sampling resistor R1; the first end and the second end of the primary capacitor C1 are respectively used as input ends of the rectifier current limiting circuit, the first end of the primary capacitor C1 is connected to the opposite end of the primary coil S1, the same end of the secondary coil is connected to the drain of the field effect tube M1, and the source of the field effect tube M1 is connected to the second end of the primary capacitor C1; the first end of the secondary capacitor C2 string is connected to one end of the sampling resistor R1, and the sampling resistor R1 The other end serves as an output end of the rectifier current limiting circuit, and the second end of the secondary capacitor C2 string serves as another output end of the rectifier current limiting circuit; in the secondary capacitor C2 string, each secondary capacitor C2 is connected in parallel with the same structure, which includes a diode D1 and a secondary coil S2, the cathode of the diode D1 is connected to the first end of the secondary capacitor C2, the same-name end of the secondary coil S2 is connected to the anode of the diode D1, the opposite-name end of the secondary coil S2 is connected to the second end of the secondary capacitor C2, and the secondary coil S2 and the primary coil S1 form a transformer structure.

[0027] When the FET M1 is turned on, the induced voltage of the primary coil S1 is positive at the top and negative at the bottom, the rectifier diode D1 is in the off state, and energy is stored in the primary coil S1. When the FET M1 is turned off, the energy stored in the primary coil S1 is rectified by the secondary coil S2 and the diode D1 and filtered by the secondary capacitor C2 before being output to the output end.

[0028] The rectifier current limiting circuit adopts the output series flyback circuit topology, and the sampling resistor R1 (generally manganese copper sampling resistor R1) is connected in series on the output side. The flyback circuit has the characteristics of constant current output. During the charging process of the sub-module capacitor, the output current is constant and allows long-term operation.

[0029] The above circuit uses multiple parallel charging branches to charge multiple flexible DC converter valve sub-modules to improve the charging efficiency, and an isolation circuit is set in the charging branch. An embedded resistor is connected between the negative output ends of adjacent charging branches to effectively prevent adjacent series sub-modules from affecting each other. There is no need to remove the connecting copper busbars between the sub-modules, which further improves the charging efficiency.

[0030] based on Figure 1 A multi-channel isolation and pressure-increasing method based on the multi-channel isolation and pressure-increasing circuit is disclosed herein, specifically, charging multiple series-connected flexible DC converter valve submodules. Before charging, the charging branch is connected to the submodule to be charged, and the controllable module in the multi-channel isolation and pressure-increasing circuit, such as the controllable switch lamp, is controlled to charge the submodule.

[0031] The multi-channel isolation and boosting method based on the multi-channel isolation and boosting circuit can realize multi-channel simultaneous charging, and generally can realize the charging of 1 to 16 sub-modules, thereby improving the charging efficiency.

[0032] based on Figure 1 A circuit is disclosed herein, and a multi-channel isolation and pressure-increasing test device including the multi-channel isolation and pressure-increasing circuit is also disclosed herein, which specifically includes a control card board, an RC detection module, a high-voltage charging and discharging module, and a host computer.

[0033] The control card board includes IO board, CO board, PU board, MC board and 24V power supply board.

[0034] IO board: responsible for collecting the test switch status of the valve base control equipment, as well as the output of commands and status. The IO board has 16 digital input interfaces and 16 digital output interfaces, all of which are +24V voltage signals. Figure 4 The IO board input interface is responsible for receiving signals from the automatic test, charging, running, discharging, reset buttons, and emergency stop switch signals; the IO board output interface is responsible for controlling the on and off of the discharge switch, controlling the opening or closing of the charging power supply, and controlling the status indicator light on the IO panel.

[0035] CO board: Communicates with the host computer software. Through the communication board, users can not only observe the real-time status intuitively, but also issue instructions through the communication protocol.

[0036] The first PU board is mainly responsible for communicating with the RC detection module. The second PU board is the interface between the device controller and the power module. It is responsible for sending the instructions issued by the controller main control board to the power module after processing, and receiving the data returned by the power module and transmitting it to the controller main control board. Optical fiber is used externally to isolate high and low voltages, while enhancing the signal's anti-interference ability.

[0037] MC board: mainly responsible for the work scheduling, data processing and transmission of all functional boards in the system. 24V power board: supplies the 24V power required by MC, PU, ​​IO, and CO boards.

[0038] The high-voltage charge and discharge module mainly includes a discharge circuit and the above-mentioned multi-channel isolation pressure-boosting circuit. The high-voltage charge and discharge module is connected to the IO board, receives the charge and discharge enable signal of the IO board, and the output end is connected to the DC positive and negative poles of the sub-module under test to perform corresponding operations on the module capacitor.

[0039] The RC detection module input connects the DC positive and negative poles of the module and the two ends of the AC side of the module to collect capacitor voltage, charging current and AC voltage values. The sampled values ​​are sent to the first PU board of the controller through optical fiber communication via FPGA.

[0040] Figure 3 A multi-channel isolated pressure test device for pressurizing and charging a single submodule. If multiple submodules are pressurized and charged, it is only necessary to lead out multiple output lines from the high-voltage charging and discharging module.

[0041] The host computer mainly displays the test results and data, specifically whether the low-voltage pressurization test is passed, the capacitor voltage value of the test submodule, etc.

[0042] It should be noted that the multi-channel isolation pressure test device inputs 220V AC power to charge 1 to 16 submodules to 800V, which can simulate the inverter unlocking operation under low voltage conditions. The specific requirements are as follows: (1) The power supply mode adopts the mains voltage of 220V (AC), the allowable power supply voltage range is 176V-264V (AC), and the allowable power supply frequency is 50Hz / 60Hz.

[0043] (2) The voltage-equalizing resistor of the submodule is 34KΩ, and the power consumption of each board is about 20W. The current consumption at 800V is 800 / 34000+20 / 800=0.0485A. To ensure a faster charging speed, the charging current needs to be designed to 0.2A or above.

[0044] (3) The starting voltage of the submodule is 500V, and the maximum output voltage of the charging power board should not be lower than 700V. In order to ensure the reliable operation of each board and consider the test accuracy and test efficiency of the device, the maximum output voltage of the charging power board is suitable to be set to 800V.

[0045] (5) The high voltage sampling circuit in the RC detection module uses a 100:1 ratio to reduce the submodule capacitor voltage and the submodule AC terminal voltage, and then sends the isolated signal to the digital display circuit and AD board after passing through the analog signal isolation circuit.

[0046] (6) Responsible for collecting the test switch status of the valve base control equipment, as well as the output of commands and status. It has 16 digital input interfaces and 16 digital output interfaces, all of which are +24V voltage signals. Figure 4 The IO board input interface is responsible for receiving signals from the automatic test, charging, running, discharging, reset buttons, and emergency stop switch signals; the IO board output interface is responsible for controlling the on and off of the discharge switch, controlling the opening or closing of the charging power supply, and controlling the status indicator light on the IO panel.

[0047] (7) The digital display tube is installed on the charging power panel, which displays the unit voltage, unit IEGT midpoint (AC) voltage, and unit input current respectively.

[0048] (8) The communication board model is CO-V04B, which uses a 400MHz PowerPC chip and provides a variety of external communication interfaces, including RS232, RS485, USB, SD / MMC, Ethernet, and CAN interfaces. A variety of upper-layer communication protocols can be developed on this basis. Through the communication board, users can not only intuitively observe the real-time status of the system, but also send instructions to the system through a variety of communication protocols.

[0049] (9) The withstand voltage between the AC input port and the test device housing is not less than 1500V (AC), and the withstand voltage between the high voltage output terminal, high voltage sampling output terminal and the test device housing is not less than 1600V (DC) Based on the above method, a multi-channel isolation and pressure-increasing testing method is also disclosed herein, which specifically uses the above-mentioned multi-channel isolation and pressure-increasing circuit to charge multiple flexible DC converter valve sub-modules connected in series, and performs functional testing on the sub-modules that have completed charging, and can specifically perform sub-module configuration, sub-module reset, sub-module status monitoring, no-load wave generation, RC constant calculation, bypass test, sub-module temperature sampling monitoring, sub-module temperature sampling monitoring, etc.

[0050] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Multi-channel isolation pressure boosting circuit, characterized in that: It includes multiple parallel charging branches, the input end of the charging branch inputs external AC power, and the output end of the charging branch is externally connected to the input end of the flexible DC converter valve submodule; the charging branch includes an isolation circuit and a rectifier current limiting circuit connected in series from the input end to the output end; and a clamping resistor is connected between the negative output ends of adjacent charging branches.

2. The multi-channel isolation pressure-boosting circuit according to claim 1, characterized in that: The rectifier current limiting circuit includes a primary coil, a primary capacitor, a field effect transistor, a secondary capacitor string and a sampling resistor; The first end and the second end of the primary capacitor are respectively used as input ends of the rectifier current limiting circuit, the first end of the primary capacitor is connected to the opposite end of the primary coil, the same end of the primary coil is connected to the drain of the field effect tube, and the source of the field effect tube is connected to the second end of the primary capacitor; A first end of the secondary capacitor string is connected to one end of the sampling resistor, the other end of the sampling resistor serves as an output end of the rectifier current limiting circuit, and a second end of the secondary capacitor string serves as another output end of the rectifier current limiting circuit; In the secondary capacitor string, each secondary capacitor is connected in parallel with the same structure, which includes a diode and a secondary coil, the cathode of the diode is connected to the first end of the secondary capacitor, the same-name end of the secondary coil is connected to the anode of the diode, the opposite-name end of the secondary coil is connected to the second end of the secondary capacitor, and the secondary coil and the primary coil form a transformer structure.

3. The multi-channel isolation pressure-boosting circuit according to claim 1, characterized in that: The input ends of all charging branches are input with external AC power through a controllable main switch.

4. The multi-channel isolation boosting circuit according to claim 1, characterized in that: A controllable sub-switch is also connected in series in the charging branch.

5. The multi-channel isolation pressure-boosting circuit according to claim 4, characterized in that: The controllable sub-switch is connected in series upstream of the isolation circuit.

6. Multi-channel isolation pressurization method, characterized in that: The circuit described in any one of claims 1 to 5 is used to charge a plurality of flexible DC converter valve submodules connected in series.

7. Multi-channel isolation pressure test device, characterized in that: A circuit comprising any one of claims 1 to 5.

8. A multi-channel isolation pressure test method, characterized in that: include: Using the circuit described in any one of claims 1 to 5 to charge a plurality of series-connected flexible DC converter valve submodules; Perform functional test on the submodules that have completed charging.

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