Power device parallel type power module and capacitor charging and discharging method

Abstract

A kind of power device parallel type power module and capacitor charging and discharging method, power module includes two or more than pressure type power device, the two or more than pressure type power device adopts the physical form of half bridge group string upper and lower parallel;The half bridge group string of the pressure type power device is connected in parallel by silicon pile composite busbar;Each power module is provided with pneumatic short-circuit switch, in the case of multiple power module series connection, the pneumatic short-circuit switch is connected in series with all DC capacitors, and charging and discharging is carried out through the ground loop of flexible AC transmission equipment AC, DC valve side;The pneumatic short-circuit switch is connected with gas driving pipeline, and the gas driving pipeline is connected with valve-based gas pressurizing device.The power module can effectively improve the capacity of flexible AC transmission equipment, so that it has short-time frequency modulation capacity output, provides technical scheme support for new power system construction, and guarantees system safety and stability;The provided capacitor charging and discharging method can improve maintenance efficiency and enhance product reliability.

Description

Technical Field

[0001] This invention belongs to the field of flexible DC transmission technology, specifically relating to a power module with parallel power devices and a capacitor charging and discharging method. Background Technology

[0002] The new power system is a power system with a robust and intelligent grid as its hub platform, supported by the interaction of power generation, grid, load, and storage, as well as multi-energy complementarity. It possesses the fundamental characteristics of being clean and low-carbon, safe and controllable, flexible and efficient, intelligent and user-friendly, and open and interactive. Simultaneously, the new power system prioritizes ensuring energy security, aims to meet the electricity demands of economic and social development, and focuses on maximizing the absorption of new energy sources. Flexible DC transmission technology, as a novel DC transmission technology, is one of the best solutions for grid connection of renewable energy sources such as wind power, and is also a crucial technology for constructing the new power system. Its core component, the flexible DC converter valve, will receive wider research and application.

[0003] With a high proportion of new energy sources and a high proportion of power electronic equipment connected to the grid, the dynamic characteristics of the power system are changing, and frequency stability will face enormous challenges. There is an urgent need to develop new power electronic equipment to provide short-term inertia support to ensure system stability.

[0004] Currently, conventional flexible DC transmission systems can transfer frequency-modulated energy from a normal AC system to a disturbed AC system via the DC system, but this can affect the stable operation of the normal AC system. Therefore, flexible DC transmission systems need to be designed with reserved frequency regulation capacity, requiring the flexible DC converter valves to operate under short-term, doubling-load overload conditions. Developing high-capacity flexible DC converter valves is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0005] The purpose of this invention is to address the problems in the prior art by providing a parallel power module for power devices and a capacitor charging and discharging method, thereby increasing the capacity of the flexible DC converter valve, enabling it to have short-time frequency regulation capacity output, ensuring frequency stability of the new power system, improving maintenance efficiency, and enhancing product reliability.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A parallel power module for power devices, to improve the current carrying capacity of the power module, uses two or more press-fit IGBTs and their anti-parallel diodes connected in parallel for both the upper and lower transistors. When there are two press-fit IGBTs and two anti-parallel diodes, the first IGBT, the first diode of the upper transistor, the first IGBT of the lower transistor, the first diode of the lower transistor, and the heat sink form a half-bridge group in series one; the second IGBT, the second diode of the upper transistor, the second IGBT of the lower transistor, the second diode of the lower transistor, and the heat sink form a half-bridge group in series two. When the parallel press-fit IGBTs are connected in series two... When the number of IGBTs and anti-parallel diodes both exceed two, the same method is used to construct half-bridge strings; multiple half-bridge strings are arranged horizontally and vertically; the equipotential points of the multiple half-bridge strings are connected through a silicon stack composite busbar; each power module is equipped with a pneumatic short-circuit switch, and when multiple power modules are connected in series, the pneumatic short-circuit switch connects all DC capacitors in series, and charges and discharges them through the AC and DC valve-side grounding circuit of the flexible DC converter valve; the pneumatic short-circuit switch is connected to a gas drive pipeline, and the gas drive pipeline is connected to a valve-based gas pressurization device.

[0008] As a preferred embodiment of the parallel power module of the present invention, the AC and DC valve-side grounding circuits of the flexible DC converter valve are configured with an AC grounding switch, a DC grounding switch, a discharge resistor, a current measuring device, a voltage measuring device, a tap changer, and an external DC power supply; the tap changer and the external DC power supply are connected in series; one end of the discharge resistor is connected to the external DC power supply, and the other end is grounded; the current measuring device and the voltage measuring device are connected in parallel.

[0009] As a preferred embodiment of the parallel power module of the present invention, the press-fit power device uses a dual-section heat sink with parallel water channels for heat dissipation. The dual-section heat sink includes two sub-heat sinks, which are connected into one unit by a sub-section connecting water pipe. The two sub-heat sinks are respectively provided with a main inlet and outlet, and each sub-heat sink is provided with an inlet and outlet water channel. The corresponding water channel interfaces are connected into one unit by the sub-section connecting water pipe.

[0010] As a preferred embodiment of the parallel power module of the power device of the present invention, the main inlet and outlet are equipped with exposed stainless steel electrode heads; the stainless steel electrode heads are respectively connected to the double-panel radiator and the external water pipe via threads.

[0011] As a preferred embodiment of the parallel power module of the present invention, the silicon stack composite busbar is composed of multiple layers of materials, including copper plates and insulating plates. The silicon stack composite busbar connects the equipotential heat sinks of multiple half-bridge strings, and the corresponding C- and C+ terminals of the silicon stack composite busbar are connected to the composite busbar of all DC capacitors.

[0012] As a preferred embodiment of the parallel power module of the present invention, the pneumatic short-circuit switch includes a positive base, a positive copper strip, a positive gas cover, a flexible negative claw, a negative base, and a gas interface; the flexible negative claw connects to the negative terminal of the corresponding DC capacitor of this power module, and the positive copper strip connects to the positive terminal of the corresponding DC capacitor of the adjacent power module; the flexible negative claw is connected to the gas drive pipeline through the gas interface; both the flexible negative claw and the positive copper strip are disposed inside the sealed positive gas cover, and the flexible negative claw includes two or more claws evenly arranged in a circle. When the internal air pressure of the positive gas cover is less than a set value, a fixed spatial distance is maintained between the flexible negative claw and the positive gas cover; when the internal air pressure of the positive gas cover is increased through the gas drive pipeline and exceeds the set value, the flexible negative claw bends outward and contacts the positive copper strip, thereby short-circuiting the positive and negative terminals of the corresponding DC capacitors of the adjacent power modules together.

[0013] As a preferred embodiment of the parallel power module of the present invention, the valve-based gas pressurization device is equipped with a manual valve with an interlocking mechanism, which cannot be opened when the power module is working normally.

[0014] A capacitor charging and discharging method for a parallel power module of the aforementioned power devices, comprising:

[0015] When the DC capacitor needs to be charged, the corresponding pneumatic short-circuit switches configured in multiple power modules, as well as the DC grounding switch and tap changer, are all closed to form a closed loop, and the DC capacitor is charged through an external DC power supply.

[0016] When the DC capacitor needs to be discharged, the corresponding pneumatic short-circuit switches configured in multiple power modules, as well as the AC grounding switch and DC grounding switch, are all closed to form a closed loop, and the DC capacitor is discharged through the discharge resistor.

[0017] As a preferred embodiment of the capacitor charging and discharging method of the present invention, the voltage measuring device measures the voltage across multiple power modules connected in series to obtain the voltage of multiple series-connected DC capacitors; the current measuring device and the voltage measuring device feed the sampling signal back to the valve control system to monitor the charging and discharging status of the DC capacitors in real time.

[0018] As a preferred embodiment of the capacitor charging and discharging method of the present invention, after the DC capacitor is charged to the voltage threshold, the pneumatic short-circuit switch, the DC grounding switch and the tap changer are disconnected, and the power module itself is functionally tested through the valve base controller of the power module. The test content includes the normal operation test of the power module bypass switch.

[0019] Compared with existing technologies, the parallel power module of the present invention has at least the following beneficial effects:

[0020] Two or more press-fit power devices are connected in parallel in a half-bridge string configuration. These press-fit power devices can be IGBTs or diodes. The half-bridge strings of press-fit power devices are connected in parallel via a silicon stack composite busbar. Each power module is equipped with a pneumatic short-circuit switch. When multiple power modules are connected in series, the pneumatic short-circuit switch connects all DC capacitors in series, allowing charging and discharging through the AC and DC valve-side grounding circuits of the flexible DC converter valve. This invention's parallel power module configuration improves the consistency of key parameters when power devices are used in parallel. Simultaneously, the flexible DC converter valve composed of this invention's parallel power module configuration can provide short-term inertia support to the AC system, ensuring frequency stability in the new power system. It can also increase the capacity of the flexible DC converter valve, enabling it to have short-term frequency regulation capacity output and meeting the requirements for short-term doubling overload operation. This provides technical support for the construction of new power systems and ensures system safety and stability.

[0021] Compared to existing technologies, the capacitor charging and discharging method for parallel power modules of the present invention has at least the following beneficial effects: The provided capacitor discharging method can prevent electric shock during maintenance personnel. The provided capacitor charging method can quickly perform functional checks on all power modules of the converter valve, improving maintenance efficiency and enhancing product reliability. The method of the present invention can quickly perform functional checks on all power modules of the converter valve, improving maintenance efficiency and enhancing product reliability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1(a) is a three-dimensional schematic diagram of the parallel power module structure of the power devices according to an embodiment of the present invention;

[0024] Figure 1(b) Front view of the parallel power module structure of the power devices according to an embodiment of the present invention;

[0025] Figure 2(a) Front view of the assembly structure of the press-fit power device according to an embodiment of the present invention;

[0026] Figure 2(b) is a three-dimensional schematic diagram of the assembly structure of the press-fit power device according to an embodiment of the present invention;

[0027] Figure 3(a) Front view of the dual-panel heat sink structure according to an embodiment of the present invention;

[0028] Figure 3(b) Side view of the dual-panel radiator structure according to an embodiment of the present invention;

[0029] Figure 4 Electrical topology diagram of the power module according to an embodiment of the present invention;

[0030] Figure 5(a) is a three-dimensional schematic diagram of the pneumatic short-circuit switch structure according to an embodiment of the present invention;

[0031] Figure 5(b) is a three-dimensional schematic diagram of the flexible negative claw structure of the pneumatic short-circuit switch according to an embodiment of the present invention;

[0032] Figure 5(c) is a three-dimensional schematic diagram of the positive electrode gas cover structure of the pneumatic short-circuit switch according to an embodiment of the present invention;

[0033] Figure 6 A schematic diagram illustrating the wiring principle of the capacitor charging and discharging method according to an embodiment of the present invention;

[0034] In the attached diagram: 1. DC capacitor; 2. Valve base controller; 3. External DC power supply; 4. Drive board assembly; 5. AC output terminal; 6. C- output terminal; 7. Tap changer; 81. Upper diode D1-1; 82. Upper diode D1-2; 91. Upper IGBT T1-1; 92. Upper IGBT T1-2; 101. Lower IGBT T2-1; 102. Lower IGBT T2-2; 111, Lower diode D2-1; 112, Lower diode D2-2; 12, Dual-panel heat sink; 121, Sub-heat sink one; 122, Sub-heat sink two; 123, Main inlet; 124, Main outlet; 125, Sub-outlet connecting pipe; 126, Sub-inlet connecting pipe; 127, Stainless steel electrode head; 13, Silicon stack composite busbar; 141, First capacitor composite busbar; 142, Second capacitor composite busbar; 15, Pneumatic short-circuit switch; 151, Positive base; 152, Positive copper strip; 153, Positive gas shield; 154, Flexible negative claw; 155, Negative base; 156, Gas interface; 16, Switch negative connection bar; 17, Gas drive pipeline. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0036] Based on the embodiments of the present invention, those skilled in the art can make several simple modifications and refinements without creative effort, and all other embodiments obtained are within the scope of protection of the present invention.

[0037] In this invention, reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0038] Referring to Figures 1(a) and 1(b), the parallel power module proposed in this invention includes two or more press-fit power devices, which are IGBTs and diodes. Referring to Figures 2(a) and 2(b), the two or more press-fit power devices are arranged horizontally and vertically in the form of half-bridge strings. Referring to Figures 3(a) and 3(b), the power devices are cooled by a dual-channel heat sink 12 with parallel water channels. The dual-channel heat sink is divided into two sub-heat sinks (sub-heat sink one 121 and sub-heat sink two 122), which are connected into one unit by sub-connecting water pipes (sub-outlet connecting pipe 125 and sub-inlet connecting pipe 126). The two or more half-bridge strings are connected in parallel through a low-stray silicon stack composite busbar 13. The silicon stack composite busbar 13 is composed of multiple layers of copper plates and insulating plates. This invention also proposes a capacitor charging and discharging method for a parallel power module of the aforementioned power devices. Each power module is equipped with a pneumatic short-circuit switch. When multiple power modules are connected in series, the pneumatic short-circuit switch connects all DC capacitors 1 in series and charges and discharges them through the AC and DC valve-side grounding circuits of the flexible DC converter valve. The charging and discharging circuit is equipped with an AC grounding switch, a DC grounding switch, a discharge resistor, a current measuring device, a voltage measuring device, a tap changer, and an external DC power supply 3. The pneumatic short-circuit switches 15 and the branches of the gas drive pipeline 17 of the multiple power modules are connected in parallel and connected to the main gas drive pipeline. The valve-based gas pressurization device controls the closing or opening of all pneumatic short-circuit switches 15.

[0039] The two sub-radiators of the dual-unit radiator (sub-radiator 121 and sub-radiator 22) have a main water inlet 123 and a main water outlet 124. Each sub-radiator (sub-radiator 121 and sub-radiator 22) is provided with water inlet and water outlet channels. The corresponding sub-channel interfaces are connected into one unit by sub-connecting water pipes (sub-outlet connecting pipe 125 and sub-inlet connecting pipe 126). The main water inlet and water outlet of the dual-unit radiator are equipped with exposed stainless steel electrode heads 127. The stainless steel electrode heads 127 have an external thread structure, with one end screwed into the radiator and the other end exposed to connect to the external water pipe.

[0040] In one possible implementation, the silicon stack composite busbar 13 connects the heat sinks of multiple half-bridge strings in parallel; the corresponding C- and C+ terminals of the silicon stack composite busbar 13 are connected to the first capacitor composite busbar 141 and the second capacitor composite busbar 142 via small flexible copper busbars. Referring to Figures 5(a), 5(b), and 5(c), the pneumatic short-circuit switch 14 includes a positive base 151, a positive copper strip 152, a positive gas cover 153, a flexible negative claw 154, a negative base 155, and a gas interface 156; the flexible negative claw 154 is connected to the negative terminal of the capacitor of this power module, the positive copper strip 152 is connected to the positive terminal of the capacitor of the adjacent power module, and the positive base 151 is connected to the positive copper strip 152; the flexible negative claw 154 is designed with a gas interface 156, which is connected to the gas drive pipeline. In this embodiment, the flexible negative claw 154 consists of three claws arranged evenly in a circle. The inside of the positive electrode gas cover 153 is a connected sealed cavity, and the flexible negative claw 154 is placed inside the positive electrode gas cover 153. When the internal air pressure is less than a set value, the flexible negative claw 154 maintains a fixed spatial distance from the positive electrode copper strip 152. When the internal air pressure is increased through the gas drive pipeline and exceeds the set value, the flexible negative claw 154 bends outward and contacts the positive electrode copper strip 152, thereby short-circuiting the positive and negative terminals of the adjacent power module capacitors together.

[0041] See Figure 6 Another embodiment proposes a capacitor charging and discharging method for the parallel power module of the power devices, comprising:

[0042] When DC capacitor 1 needs to be charged, the corresponding pneumatic short-circuit switches 15 configured by multiple power modules, as well as the DC grounding switch and tap switch 7, are all closed to form a closed circuit, and DC capacitor 1 is charged through the external DC power supply 3.

[0043] When DC capacitor 1 needs to be discharged, the corresponding pneumatic short-circuit switches 15 configured by multiple power modules, as well as the AC grounding switch and DC grounding switch, are all closed to form a closed loop, and DC capacitor 1 is discharged through the discharge resistor.

[0044] The current measuring device measures the current of the capacitor during charging and discharging; the voltage measuring device measures the voltage across multiple series-connected power modules, thus obtaining the voltage of multiple series-connected DC capacitors 1; the current measuring device and the voltage measuring device feed back the sampling signals to the valve control system so as to monitor the charging and discharging status of DC capacitors 1 in real time.

[0045] Furthermore, the valve-based gas pressurization device includes a gas compressor, a manual valve, and an interlocking mechanism on the valve; the interlocking mechanism prevents the manual valve from opening when the power module is working normally, and the valve can only be opened when the power module is stopped.

[0046] Furthermore, after DC capacitor 1 is charged to the voltage threshold, the pneumatic short-circuit switch 15, DC grounding switch, and tap changer 7 are disconnected; the power module's valve base controller is used to perform functional tests, including normal operation tests of the bypass switch.

[0047] The parallel power module and capacitor charging / discharging method proposed in this invention can effectively improve the capacity of flexible DC converter valves, enabling them to have short-term frequency regulation capacity output, providing technical support for the construction of new power systems, and ensuring system safety and stability. The provided capacitor discharging method can prevent electric shock to maintenance personnel when maintaining the product. The provided capacitor charging method can quickly perform functional checks on all power modules of the converter valve, improving maintenance efficiency and enhancing product reliability.

[0048] The present invention has been described above in conjunction with specific features and embodiments. It is obvious that various modifications and combinations can be made without departing from the spirit and scope of the invention. Accordingly, this specification and accompanying drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the present invention, and these modifications and modifications that do not depart from the spirit and scope of the invention also fall within the scope of the claims and their equivalents.

Claims

1. A power module with parallel power devices, characterized in that: To improve the current carrying capacity of the power module, both the upper and lower IGBTs use two or more press-fit IGBTs and their anti-parallel diodes connected in parallel. When there are two press-fit IGBTs and two anti-parallel diodes, the first IGBT, first diode, first IGBT, and first diode of the upper and lower IGBTs, along with the heat sink, form a half-bridge group in series (Series 1); the second IGBT, second diode, second IGBT, and second diode of the upper and lower IGBTs, along with the heat sink, form a half-bridge group in series (Series 2). When the number of press-fit IGBTs and two anti-parallel diodes both exceed two, ... The same method is used to construct the half-bridge string; multiple half-bridge strings are arranged horizontally and vertically; the equipotential points of the multiple half-bridge strings are connected through the silicon stack composite busbar (13); each power module is equipped with a pneumatic short-circuit switch (15). When multiple power modules are connected in series, the pneumatic short-circuit switch (15) connects all DC capacitors (1) in series and charges and discharges them through the AC and DC valve side grounding circuit of the flexible DC converter valve; the pneumatic short-circuit switch (15) is connected to the gas drive pipeline (17), and the gas drive pipeline (17) is connected to the valve base gas pressurization device.

2. The parallel power module of power devices according to claim 1, characterized in that: The AC and DC valve side grounding circuits of the flexible DC converter valve are equipped with an AC grounding switch, a DC grounding switch, a discharge resistor, a current measuring device, a voltage measuring device, a tap changer (7), and an external DC power supply (3); the tap changer (7) and the external DC power supply (3) are connected in series; one end of the discharge resistor is connected to the external DC power supply (3), and the other end is grounded; the current measuring device and the voltage measuring device are connected in parallel.

3. The parallel power module of power devices according to claim 1, characterized in that: The press-fit power device uses a dual-section heat sink with parallel water channels for heat dissipation. The dual-section heat sink includes two sub-heat sinks, which are connected into one unit by a connecting water pipe. The two sub-heat sinks are respectively provided with a main inlet and outlet, and each sub-heat sink is provided with an inlet and outlet water channel. The corresponding water channel interfaces are connected into one unit by the connecting water pipe.

4. The parallel power module of power devices according to claim 3, characterized in that: The main inlet and outlet are equipped with exposed stainless steel electrode heads (127); the two ends of the stainless steel electrode heads (127) are respectively connected to the double-panel radiator and the external water pipe via threads.

5. The parallel power module of power devices according to claim 1, characterized in that: The silicon stack composite busbar (13) is composed of multiple layers of copper plate and insulating plate. The silicon stack composite busbar (13) connects multiple half-bridge strings of equipotential heat sinks. The corresponding C- and C+ terminals of the silicon stack composite busbar (13) are connected to the composite busbar of all DC capacitors (1).

6. The parallel power module of power devices according to claim 1, characterized in that: The pneumatic short-circuit switch (15) includes a positive base (151), a positive copper strip (152), a positive gas cover (153), a flexible negative claw (154), a negative base (155), and a gas interface (156); the flexible negative claw (154) is connected to the negative terminal of the corresponding DC capacitor (1) of this power module, and the positive copper strip (152) is connected to the positive terminal of the corresponding DC capacitor (1) of the adjacent power module; the flexible negative claw (154) is connected to the gas drive pipeline (17) through the gas interface (156); both the flexible negative claw (154) and the positive copper strip (152) are Set inside the sealed positive electrode gas shield (153), the flexible negative claw (154) includes two or more claws arranged in a circular pattern. When the internal air pressure of the positive electrode gas shield (153) is less than a set value, the flexible negative claw (154) maintains a fixed spatial distance from the positive electrode gas shield (153). When the internal air pressure of the positive electrode gas shield (153) is increased through the gas drive pipe (17) and exceeds the set value, the flexible negative claw (154) bends outward and contacts the positive electrode copper strip (152), thereby short-circuiting the positive and negative terminals of the DC capacitor (1) corresponding to the adjacent power module together.

7. The parallel power module of power devices according to claim 1, characterized in that: The valve-based gas pressurization device is equipped with a manual valve with an interlocking mechanism, which cannot be opened when the power module is working normally.

8. A capacitor charging and discharging method for a parallel power module of power devices as described in claim 2, characterized in that: When the DC capacitor (1) needs to be charged, the corresponding pneumatic short-circuit switches (15) configured by multiple power modules, as well as the DC grounding switch and tap switch (7) are all closed to form a closed loop, and the DC capacitor (1) is charged by the external DC power supply (3). When the DC capacitor (1) needs to be discharged, the corresponding pneumatic short-circuit switches (15) configured by multiple power modules, as well as the AC grounding switch and the DC grounding switch are all closed to form a closed loop, and the DC capacitor (1) is discharged through the discharge resistor.

9. The capacitor charging and discharging method according to claim 8, characterized in that: The voltage measuring device measures the voltage across multiple power modules connected in series to obtain the voltage of multiple series-connected DC capacitors (1); the current measuring device and the voltage measuring device feed the sampling signal back to the valve control system to monitor the charging and discharging state of the DC capacitors (1) in real time.

10. The capacitor charging and discharging method according to claim 8, characterized in that: After the DC capacitor (1) is charged to the voltage threshold, the pneumatic short-circuit switch (15), DC grounding switch and tap switch (7) are disconnected. The power module itself is functionally tested by the valve base controller (2) of the power module. The test content includes the normal operation test of the power module bypass switch.

Images