Hybrid direct-current energy consumption device

Abstract

The utility model provides a hybrid direct current energy consumption device which comprises an energy consumption valve and an energy consumption resistor. The wire inlet end of the energy consumption valve is connected with the direct-current anode direction, the wire outlet end of the energy consumption valve is connected with one end of the energy consumption resistor, and the other end of the energy consumption resistor is connected with the direct-current cathode direction. The energy consumption valve comprises a plurality of MMC sub-modules, and the plurality of MMC sub-modules are a plurality of MMC half-bridge sub-modules or a plurality of MMC full-bridge sub-modules; wherein the plurality of MMC half-bridge sub-modules or the plurality of MMC full-bridge sub-modules are of a cascade structure. The hybrid direct current energy consumption device can realize real-time control of energy consumption power.

Description

Technical Field

[0001] The utility model relates to an energy dissipation device, in particular to a hybrid direct current energy dissipation device. Background Art

[0002] In high-voltage direct current transmission systems, especially in offshore wind power flexible direct current transmission systems, direct current energy dissipation devices are crucial equipment. Direct current energy dissipation devices are mainly used in the application scenarios of renewable energy power generation and transmission. If the power generation end is an inertial power source similar to wind power, when a fault occurs at the power receiving end, the power cannot be delivered, and energy will accumulate on the direct current side, causing the voltage of the direct current transmission line to increase, which will endanger the safe operation of the equipment.

[0003] Among the existing DC energy-consuming devices, one type of power device has a "switch type" action characteristic, and the energy-consuming resistors are arranged in a concentrated manner, which has a low cost but a large switching impact; the other type of power device has a "voltage source type" action characteristic, and the energy-consuming resistors are arranged in a distributed manner, with smooth switching performance, but a water cooling system is required, which has a high cost. Utility Model Content

[0004] The utility model aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, the first purpose of the utility model is to propose a hybrid DC energy dissipation device, which can present a "voltage source type" action characteristic and the energy dissipation resistors are centrally arranged, while taking into account the advantages of centralized and distributed types, so that the hybrid DC energy dissipation device has a simple structure, low cost and is easy to implement.

[0006] In addition, the hybrid DC energy consumption device according to the above embodiment of the utility model may also have the following additional technical features:

[0007] Furthermore, in an embodiment of the present invention, when the multiple MMC sub-modules are multiple MMC half-bridge sub-modules, one end of the multiple MMC half-bridge sub-modules is connected to the DC positive direction, and the other end of the multiple MMC half-bridge sub-modules is connected to one end of the energy consumption resistor.

[0008] Furthermore, in an embodiment of the present invention, when the multiple MMC sub-modules are multiple MMC full-bridge sub-modules, one end of the multiple MMC full-bridge sub-modules is connected to the DC positive direction, and the other end of the multiple MMC full-bridge sub-modules is connected to one end of the energy consumption resistor.

[0009] Furthermore, in an embodiment of the present utility model, the energy-consuming valve is connected in series with the energy-consuming resistor.

[0010] Furthermore, in an embodiment of the present invention, the sum of the total voltage of the plurality of MMC sub-modules and the voltage of the energy-consuming resistor is the total DC voltage.

[0011] Furthermore, in one embodiment of the present invention, the MMC half-bridge submodule includes 2 IGBTs, 2 anti-parallel diodes and a DC capacitor group.

[0012] Furthermore, in an embodiment of the present invention, the capacitance in the DC capacitor group of the MMC half-bridge submodule is a minimum capacitance value that meets a preset voltage fluctuation requirement.

[0013] Furthermore, in an embodiment of the present invention, the working state of the MMC half-bridge submodule includes an on-state, a cut-off state and a locked state.

[0014] Furthermore, in one embodiment of the present invention, the MMC full-bridge submodule includes four IGBTs with anti-parallel diodes and an energy storage capacitor.

[0015] Furthermore, in one embodiment of the present invention, the working state of the MMC full-bridge submodule includes a positive input state, a negative input state, a bypass state and a locked state; each working state of the MMC full-bridge submodule has two operating modes.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and in part will become apparent from the following description or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0018] Figure 1 It is a structural schematic diagram of a hybrid DC energy dissipation device according to an embodiment of the utility model;

[0019] Figure 2 A structural diagram of an MMC half-bridge submodule according to an embodiment of the utility model;

[0020] Figure 3 Schematic diagram of three working states of an MMC half-bridge submodule according to an embodiment of the utility model;

[0021] Figure 4 A schematic diagram of the state logic operation of an MMC half-bridge submodule according to an embodiment of the utility model;

[0022] Figure 5 A structural diagram of an MMC full-bridge submodule according to an embodiment of the utility model;

[0023] Figure 6 A schematic diagram of the working state and current direction of an MMC full-bridge submodule according to an embodiment of the utility model;

[0024] Figure 7 The figure is a schematic diagram of the state logic operation of the MMC full-bridge submodule according to an embodiment of the utility model. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] The hybrid DC energy dissipation device according to an embodiment of the utility model will be described below with reference to the accompanying drawings.

[0027] Figure 1 A schematic diagram of the structure of a hybrid DC energy dissipation device provided in an embodiment of the utility model.

[0028] like Figure 1 As shown, the hybrid DC energy consumption device includes an energy consumption valve 100 and an energy consumption resistor 200; the inlet end of the energy consumption valve 100 is connected to the DC positive pole direction, the outlet end of the energy consumption valve 200 is connected to one end of the energy consumption resistor 200, and the other end of the energy consumption resistor 200 is connected to the DC negative pole direction; the energy consumption valve 100 includes multiple MMC sub-modules, and the multiple MMC sub-modules are multiple MMC half-bridge sub-modules or multiple MMC full-bridge sub-modules; wherein the multiple MMC half-bridge sub-modules or multiple MMC full-bridge sub-modules are cascaded structures.

[0029] It is understandable that in the offshore wind power flexible DC transmission system, after the offshore wind turbine is boosted to 35kV through the box transformer, the electric energy is collected to the offshore booster station, which boosts the voltage to 230kV through the transformer, and then converts the AC power into DC power through the converter valve, and then sends it to the land converter station through the submarine high-voltage DC cable. The converter valve of the land converter station operates in the inverter state, converts the DC power into AC power and then connects it to the land power grid. The hybrid DC energy consumption device of the embodiment of the present invention is usually installed between the positive and negative busbars on the DC side of the land converter station.

[0030] Specifically, the energy-consuming valve 100 is connected in series with the energy-consuming resistor 200 .

[0031] Specifically, the sum of the total voltage of the multiple MMC sub-modules and the voltage of the energy-consuming resistor 200 is the total DC voltage.

[0032] Exemplarily, when the multiple MMC submodules are multiple MMC half-bridge submodules, one end of the multiple MMC half-bridge submodules is connected to the DC positive direction, and the other end of the multiple MMC half-bridge submodules is connected to one end of the energy dissipation resistor 200. Figure 2 shown.

[0033] Specifically, the MMC half-bridge submodule HBSM is composed of 2 IGBTs, 2 anti-parallel diodes and a DC capacitor C.

[0034] It is understandable that a diode is connected in anti-parallel to the IGBT. Since the IGBT itself is unidirectionally conductive, if there is an external inductive component, the IGBT will be directly broken down without the diode current. Therefore, the anti-parallel diode exists to protect the IGBT.

[0035] Furthermore, if Figure 3 As shown, the MMC half-bridge submodule has three working states: an on state, a cut-off state, and a locked state.

[0036] Furthermore, if Figure 4 As shown, the blocking state corresponds to both VT1 and VT2 being turned off, and whether it is mode 1 or mode 4 depends on the current direction. This state is an abnormal working state, and this working state is not allowed during normal operation. It has two functions: 1. Charging the submodule at startup; 2. Bypassing the submodule capacitor in case of a fault. The input state corresponds to VT1 being turned on and VT2 being turned off. At this time, the capacitor is put into the circuit, but whether it is mode 2 or mode 5 depends on the current direction. At this time, it can be seen that the capacitor is in the input state, but the working state of the capacitor is not necessarily discharge, it may also be charging. Therefore, it can be noted that the capacitor voltage of the MMC submodule will actually change in the working state. The removal state corresponds to VT1 being turned off and VT2 being turned on. At this time, the capacitor is removed from the circuit, but whether it is mode 3 or mode 6 depends on the current direction. At this time, the output voltage must be 0.

[0037] Exemplarily, when the multiple MMC submodules are multiple MMC full-bridge submodules, one end of the multiple MMC full-bridge submodules is connected to the DC positive pole direction, and the other end of the multiple MMC full-bridge submodules is connected to one end of the energy dissipation resistor 200. Figure 5 shown.

[0038] Specifically, the MMC full-bridge submodule consists of four IGBTs with anti-parallel diodes and energy storage capacitors.

[0039] MMC full-bridge submodule has four working states: a) positive input state; b) negative input state; c) bypass state; d) blocking state. Each working state has two operating modes according to the current direction. Figure 6 shown.

[0040] like Figure 7 As shown, it can be known that the first three working states are normal working states, and the last locking state is generally used for obstacle clearance and system startup.

[0041] It is understandable that the most obvious difference from the MMC half-bridge submodule is that the MMC full-bridge submodule has an additional negative input state. This brings an extra dimension to the control of the MMC. In addition, in the locked state, the state of the submodule is certain, that is, the capacitor must be in the bridge arm. When the half-bridge submodule is locked, the state of the capacitor is uncertain. This actually ensures that when a fault occurs, the MMC's own capacitor can be used to absorb the fault current, clear the fault current, and ensure that no oscillation occurs.

[0042] Furthermore, one of the most important aspects of the design of the modular topology of the hybrid DC energy consumption device is the design of the submodule capacitance. The submodule capacitance value determines the voltage fluctuation of the submodule, which affects the operation of the entire energy consumption device. In addition, it also has a significant impact on the size and cost of the submodule. Therefore, in this embodiment, the minimum capacitance value that meets the requirements is selected under the premise of ensuring the normal operation of the device and meeting the voltage fluctuation requirements.

[0043] According to the hybrid DC energy dissipation device proposed in the embodiment of the utility model, the power device has a "voltage source type" action characteristic and the energy dissipation resistors are arranged in a centralized manner, and the cost is low, the structure is simple, and it is easy to implement.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0045] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0046] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A hybrid DC energy consumption device, characterized in that: include: An energy-consuming valve and an energy-consuming resistor; the inlet end of the energy-consuming valve is connected to the positive direction of direct current, the outlet end of the energy-consuming valve is connected to one end of the energy-consuming resistor, and the other end of the energy-consuming resistor is connected to the negative direction of direct current; the energy-consuming valve comprises a plurality of MMC sub-modules, and the plurality of MMC sub-modules are a plurality of MMC half-bridge sub-modules or a plurality of MMC full-bridge sub-modules; wherein the plurality of MMC half-bridge sub-modules or the plurality of MMC full-bridge sub-modules are a cascade structure.

2. The hybrid DC energy dissipation device according to claim 1, characterized in that: When the multiple MMC sub-modules are multiple MMC half-bridge sub-modules, one end of the multiple MMC half-bridge sub-modules is connected to the DC positive direction, and the other end of the multiple MMC half-bridge sub-modules is connected to one end of the energy consumption resistor.

3. The hybrid DC energy dissipation device according to claim 1, characterized in that: When the multiple MMC sub-modules are multiple MMC full-bridge sub-modules, one end of the multiple MMC full-bridge sub-modules is connected to the DC positive direction, and the other end of the multiple MMC full-bridge sub-modules is connected to one end of the energy consumption resistor.

4. The hybrid DC energy dissipation device according to claim 1, characterized in that: The energy-consuming valve is connected in series with the energy-consuming resistor.

5. The hybrid DC energy dissipation device according to claim 2, characterized in that: The sum of the total voltage of the multiple MMC sub-modules and the voltage of the energy-consuming resistor is the total DC voltage.

6. The hybrid DC energy dissipation device according to claim 1, characterized in that: The MMC half-bridge submodule includes two IGBTs, two anti-parallel diodes and a DC capacitor group.

7. The hybrid DC energy dissipation device according to claim 6, characterized in that: The capacitance in the DC capacitor group of the MMC half-bridge submodule is a minimum capacitance value that meets the preset voltage fluctuation requirement.

8. The hybrid DC energy dissipation device according to claim 7, characterized in that: The working states of the MMC half-bridge submodule include an on-state, a cut-off state and a locked state.

9. The hybrid DC energy dissipation device according to claim 1, characterized in that: The MMC full-bridge submodule includes four IGBTs with anti-parallel diodes and an energy storage capacitor.

10. The hybrid DC energy dissipation device according to claim 9, characterized in that: The working states of the MMC full-bridge submodule include a positive input state, a negative input state, a bypass state and a locking state; each working state of the MMC full-bridge submodule has two operating modes.

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