Power electronic switch multiplexing type on-off-energy consumption device, control method and system

Abstract

The invention discloses a power electronic switch multiplexing type on-off-energy consumption device, a control method and a system. The device comprises a direct-current circuit breaker, a direct-current energy consumer and a mode switching module. The direct-current circuit breaker is electrically connected between the first end of the direct-current power supply and the first end of the current converter; the direct-current energy dissipater is electrically connected between two ends of the direct-current power supply, and the direct-current circuit breaker and the direct-current energy dissipater comprise the same power electronic switch module; the mode switching module is electrically connected between the power electronic switch module and the first end of the converter; according to the method, under the condition that direct current is larger than a current threshold value, a mode switching module is utilized to enable a power electronic switch module to serve as a transfer branch of a direct current circuit breaker; and under the condition that the direct-current voltage is greater than the voltage threshold value, the mode switching module is utilized to enable the power electronic switch module to control the resistor in the direct-current energy dissipater to be put into use. According to the embodiment of the invention, the system cost can be reduced while the fault ride-through capability of the system is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronics, and particularly relates to a power electronic switch multiplexing type breaking-energy consumption device, a control method and a system. BACKGROUND

[0002] The new energy sending system based on voltage source converter based high voltage direct current transmission technology (VSC-HVDC) has a broad prospect, and the modular multilevel converter (MMC) is the core equipment thereof. The modular multilevel converter based on a half-bridge sub-module has become a mainstream scheme and is widely used due to low loss, simple structure and low cost.

[0003] The modular multilevel converter based on a half-bridge sub-module faces two challenges during system fault ride-through, one is that the direct current line short circuit fault causes system overcurrent, and the other is that the excess power caused by the receiving end alternating current line fault causes system overvoltage, which affects the stable operation of the system and the transmission of new energy.

[0004] The prior art cannot improve the fault ride-through capability of the system while reducing the cost of the system. SUMMARY

[0005] The application embodiment provides a power electronic switch multiplexing type breaking-energy consumption device, a control method and a system, which can improve the fault ride-through capability of the system while reducing the cost of the system.

[0006] In a first aspect, the application embodiment provides a control method of a power electronic switch multiplexing type breaking-energy consumption device, and the power electronic switch multiplexing type breaking-energy consumption device comprises:

[0007] A direct current circuit breaker, which is electrically connected between a first end of a direct current power supply and a first end of a converter;

[0008] A direct current energy consumer, which is electrically connected between two ends of the direct current power supply, wherein the direct current circuit breaker and the direct current energy consumer comprise the same power electronic switch module;

[0009] A mode switching module, which is electrically connected between the power electronic switch module and the first end of the converter;

[0010] The method comprises:

[0011] In a case where the direct current is greater than a current threshold, the mode switching module is used to make the power electronic switch module as a transfer branch of the direct current circuit breaker;

[0012] In the case that the DC voltage is greater than the voltage threshold, the mode switching module is used to make the power electronic switching module control the resistance in the DC energy consumer to be put into use.

[0013] In a possible implementation of the first aspect, the mode switching module comprises a switch tube; the method further comprises:

[0014] In the case of normal operation, the switch tube in the mode switching module is controlled to be turned off, and the power electronic switching module is controlled to be blocked;

[0015] In the case that the DC current is greater than the current threshold, the mode switching module is used to make the power electronic switching module act as a transfer branch of the DC circuit breaker, comprising:

[0016] In the case that the DC current is greater than the current threshold, the switch tube in the mode switching module is controlled to be turned on, and the power electronic switching module is controlled to be turned on, so that the power electronic switching module acts on the transfer branch of the DC circuit breaker.

[0017] In the case that the DC voltage is greater than the voltage threshold, the mode switching module is used to make the power electronic switching module control the resistance in the DC energy consumer to be put into use, comprising:

[0018] In the case that the DC voltage is greater than the voltage threshold, the switch tube in the mode switching module is controlled to be turned off, and the power electronic switching module is controlled to be turned on, so that the power electronic switching module controls the resistance in the DC energy consumer to be put into use.

[0019] In a possible implementation of the first aspect, the mode switching module comprises a first thyristor and a second thyristor, and the first thyristor and the second thyristor are anti-parallel connected.

[0020] In a possible implementation of the first aspect, the DC circuit breaker comprises:

[0021] The mechanical switch and the auxiliary commutation unit are connected in series between the first end of the DC power supply and the first end of the converter.

[0022] The power electronic switching module is electrically connected between the first end of the DC power supply and the mode switching module.

[0023] The energy consumption branch is electrically connected between two ends of the power electronic switching module.

[0024] In a possible implementation of the first aspect, the DC energy consumer comprises:

[0025] The power electronic switching module is electrically connected between the first end of the DC power supply and the mode switching module.

[0026] The DC energy consumption sub-module is electrically connected between the mode switching module and the second end of the DC power supply.

[0027] In a possible implementation of the first aspect, the DC energy consumption submodule includes an inductor and a resistor.

[0028] The inductor and the resistor are connected in series between the first end and the second end of the DC energy consumption submodule.

[0029] In a possible implementation of the first aspect, the inductance of the inductor is k times the equivalent inductance, where k is greater than or equal to 3 and less than or equal to 5; the equivalent inductance satisfies the following formula:

[0030]

[0031] where ΔU max is the DC voltage ripple requirement, ΔU dc1 is the voltage ripple generated by the frequency of power electronic action, ΔU dc2 is the voltage ripple generated by the impact of the current on the inductor, I rate is the rated DC current, C eq is the equivalent capacitance, f S is the frequency of switching action in the power electronic switching module, L eq is the equivalent inductance, I R is the current of the resistor, and t is time.

[0032] In a possible implementation of the first aspect, the resistance of the resistor satisfies the following formula:

[0033]

[0034] where R is the resistance of the resistor, U dc is the DC voltage, P rate is the rated power.

[0035] Based on the same inventive concept, in the second aspect, the embodiments of the present application also provide a power electronic switching multiplexing type breaking-energy consumption device, which includes:

[0036] a DC circuit breaker, which is electrically connected between the first end of a DC power supply and the first end of a converter;

[0037] a DC energy consumer, which is electrically connected between the two ends of the DC power supply, wherein the DC circuit breaker and the DC energy consumer include the same power electronic switching module;

[0038] a mode switching module, which is electrically connected between the power electronic switching module and the first end of the converter;

[0039] The mode switching module is configured to:

[0040] in the case where the DC current is greater than a current threshold, the power electronic switching module is used as a transfer branch of the DC circuit breaker;

[0041] When the DC voltage is greater than the voltage threshold, the power electronic switch module controls the resistor in the DC power consumer to be put into use.

[0042] Based on the same inventive concept, in a third aspect, embodiments of this application also provide a new energy transmission system, including a DC power supply, a converter, a controller, and a power electronic switch multiplexing type switching-energy dissipation device, wherein the controller is used in the method described in any of the first aspects.

[0043] The power electronic switch multiplexing interruption-energy dissipation device, control method, and system provided in this application are as follows: The power electronic switch multiplexing interruption-energy dissipation device includes a DC circuit breaker, a DC energy dissipator, and a mode switching module. The DC circuit breaker is electrically connected between the first terminal of the DC power supply and the first terminal of the converter; the DC energy dissipator is electrically connected between the two terminals of the DC power supply, wherein the DC circuit breaker and the DC energy dissipator include the same power electronic switch module. The mode switching module is electrically connected between the power electronic switch module and the first terminal of the converter. When the DC current is greater than the current threshold, the mode switching module can be used to make the power electronic switch module act as a transfer branch of the DC circuit breaker, which can effectively deal with the system overcurrent problem caused by DC line short circuit faults and ensure the safe and stable operation of the system. When the DC voltage is greater than the voltage threshold, the mode switching module can be used to control the resistor in the DC energy dissipator to be put into use, which can quickly absorb the surplus power generated by the AC line fault at the receiving end and prevent system overvoltage. By multiplexing the power electronic switch module, the DC short circuit current interruption and resistor switching functions under fault conditions can be realized simultaneously, which can significantly save device cost and size. Attached Figure Description

[0044] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals denote the same or similar features, and the drawings are not drawn to scale.

[0045] Figure 1 This is a schematic diagram of a power electronic switch multiplexing type switching-energy dissipation device provided in an embodiment of this application;

[0046] Figure 2 This is a schematic flowchart of a control method for a power electronic switch multiplexing type switching-energy dissipation device provided in an embodiment of this application;

[0047] Figure 3 This is a schematic flowchart of a control method for a power electronic switch multiplexing type switching-energy dissipation device provided in an embodiment of this application;

[0048] Figure 4is a flow diagram of a control method of a power electronic switch multiplexed breaking-energy consumption device provided by an embodiment of the present application;

[0049] Figure 5 is another structural diagram of a power electronic switch multiplexed breaking-energy consumption device provided by an embodiment of the present application;

[0050] Figure 6 is an electrical signal change waveform diagram of a power electronic switch multiplexed breaking-energy consumption device in overcurrent;

[0051] Figure 7 is an electrical signal change waveform diagram of a power electronic switch multiplexed breaking-energy consumption device in overvoltage;

[0052] Figure 8 is a structural diagram of a new energy sending-out system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0053] The features and exemplary embodiments of various aspects of the present application will be described in detail below with reference to the drawings. The following detailed description is merely intended to explain the present application and is not intended to limit the present application. The present application can be implemented without some of the specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by showing examples of the present application.

[0054] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element defined by the statement "comprises... " does not exclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0055] It should be understood that the term "and / or" as used herein merely describes an associated relationship between associated objects, and indicates that there can be three relationships, for example, A and / or B, which can represent three cases of A existing alone, A and B existing simultaneously, and B existing alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0056] Various modifications and changes can be made to the present application in matters of form and detail without departing from the spirit and scope of the application. It is therefore intended that the application cover all modifications and changes as fall within the scope of the claims (the technical solutions claimed to be protected) and their equivalents. It should be noted that the embodiments provided by the present application can be combined with each other without contradiction, if possible.

[0057] Before describing the technical solutions provided by the embodiments of the present application, in order to facilitate the understanding of the embodiments of the present application, the present application first specifically describes the problems existing in the related art:

[0058] The new energy sending-out system based on voltage source converter based high voltage direct current transmission technology (VSC-HVDC) has broad prospects, and the modular multilevel converter (MMC) is the core equipment thereof. The modular multilevel converter based on half-bridge sub-modules has become a mainstream scheme and is widely used due to low loss, simple structure and low cost.

[0059] The modular multilevel converter based on half-bridge sub-modules faces two challenges during system fault ride-through. One is that the short-circuit fault of the DC line causes overcurrent of the system, and the current needs to be broken in time. The other is that the excess power caused by the fault of the receiving end AC line causes overvoltage of the system, and the power needs to be quickly absorbed.

[0060] The inventors discovered that there are two main approaches to clearing DC short-circuit faults in Modular Multilevel Converters (MMCs): One approach involves blocking the MMC and disconnecting the AC-side circuit breaker to clear the fault. However, this method is difficult to restart quickly after blocking. The other approach involves configuring a high-capacity Direct Current Circuit Breaker (DCCB) outside the MMC to interrupt the current. The DCCB consists of a main branch, a transfer branch, and a power dissipation branch. When a fault occurs, the auxiliary converter unit of the main branch disconnects, and the current is transferred to the transfer branch, which is composed of numerous IGBTs. After the main branch's mechanical switch is completely disconnected, the transfer branch shuts off, and the remaining energy is consumed by the power dissipation branch.

[0061] To address the surplus power absorption under AC faults in Modular Multilevel Converters (MMCs), some related technologies employ the addition of AC and DC power dissipation devices. AC power dissipation devices, consisting of thyristors in series with resistors, are technically effective, but due to the semi-controlled nature of thyristors, precise power control is difficult to achieve. DC power dissipation devices (DCCs) consist of numerous fully controlled power electronic switches in series with resistors. While they can achieve precise power matching, their high cost due to the large number of fully controlled power electronic switches is a significant drawback.

[0062] Therefore, the relevant technologies cannot improve the system's ability to overcome faults while reducing system costs.

[0063] Based on this, embodiments of this application provide a power electronic switch multiplexing type interruption-energy dissipation device, control method and system, which can improve the system's fault ride-through capability while reducing system costs.

[0064] The control method of the power electronic switch multiplexing type interruption-energy dissipation device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0065] Figure 1 This application provides a power electronic switch multiplexing type interruption-energy dissipation device 100, which may include a DC circuit breaker 10, a DC energy dissipator 20 and a mode switching module 30.

[0066] The DC circuit breaker 10 is electrically connected between the first end of the DC power source 200 and the first end of the converter 300.

[0067] Exemplarily, the DC circuit breaker 10 is composed of a main branch, a transfer branch and an energy dissipation branch. When a fault occurs, the auxiliary converter unit of the main branch is disconnected, the current is transferred to the transfer branch, the transfer branch is composed of a large number of IGBTs, and after the mechanical switch of the main branch is completely disconnected, the transfer branch is turned off, and the residual energy is consumed by the energy dissipation branch.

[0068] The DC energy dissipator 20 is electrically connected between the two ends of the DC power source 200, wherein the DC circuit breaker 10 and the DC energy dissipator 20 comprise the same power electronic switch module 11.

[0069] The power electronic switch module 11 is composed of a large number of fully controlled power electronic switches.

[0070] Exemplarily, the DC energy dissipator 20 is composed of the power electronic switch module 11, an inductance and a resistance in series, and can realize accurate matching of power.

[0071] The mode switching module 30 is electrically connected between the power electronic switch module 11 and the first end of the converter 300.

[0072] Figure 2 is a control method flow diagram of a power electronic switch multiplexing type breaking-energy dissipating device provided by the embodiment of the application, as shown in the figure, the method can include steps S110 and S120. Figure 2

[0073] S110, in the case that the DC current is greater than the current threshold value, the mode switching module 30 is used to make the power electronic switch module 11 as a transfer branch of the DC circuit breaker 10.

[0074] Specifically, in the case that the DC current is greater than the current threshold value, the mode switching module 30 can be used to make the power electronic switch module 11 as a transfer branch of the DC circuit breaker 10, the DC circuit breaker 10 functions, and the system overcurrent problem caused by the DC line short circuit fault can be solved, and the safe and stable operation of the system is guaranteed. This mode can be called a circuit breaker mode.

[0075] S120, in the case that the DC voltage is greater than the voltage threshold value, the mode switching module 30 is used to make the power electronic switch module 11 control the resistance in the DC energy dissipator 20 to be put into use.

[0076] ​Specifically, in the case that the DC voltage is greater than the voltage threshold, the mode switching module 30 can make the power electronic switch module 11 control the resistance in the DC energy consumer 20 to be put into use, the DC energy consumer 20 works, and the surplus power generated by the fault of the receiving end AC line can be quickly absorbed to prevent system overvoltage. This mode can be referred to as an energy consumer mode.

[0077] The control method of the power electronic switch multiplexing type breaking-energy device provided by the embodiment of the application. The power electronic switch multiplexing type breaking-energy device 100 can include a DC circuit breaker 10, a DC energy consumer 20, and a mode switching module 30. The DC circuit breaker 10 is electrically connected between the first end of a DC power source 200 and the first end of a converter 300; the DC energy consumer 20 is electrically connected between the two ends of the DC power source 200, wherein the DC circuit breaker 10 and the DC energy consumer 20 include the same power electronic switch module 11. The mode switching module 30 is electrically connected between the power electronic switch module 11 and the first end of the converter 300. In the case that the DC current is greater than the current threshold, the mode switching module 30 can make the power electronic switch module 11 act as a transfer branch of the DC circuit breaker 10, which can effectively cope with the system overcurrent problem caused by the DC line short circuit fault and guarantee the safe and stable operation of the system. In the case that the DC voltage is greater than the voltage threshold, the mode switching module 30 can make the power electronic switch module 11 control the resistance in the DC energy consumer 20 to be put into use, which can quickly absorb the surplus power generated by the fault of the receiving end AC line to prevent system overvoltage. By multiplexing the power electronic switch module 11, the functions of DC short-circuit current breaking and resistance switching under fault can be realized at the same time, which can greatly save the cost and volume of the device.

[0078] Figure 3 is another flowchart of the control method of the power electronic switch multiplexing type breaking-energy device provided by the embodiment of the application.

[0079] In some embodiments, as shown in Figure 3 the mode switching module 30 can include a switch tube. The control method can further include step S130.

[0080] S130, in the case of normal operation, control the switch tube in the mode switching module 30 to be open and the power electronic switch module 11 to be locked.

[0081] The power electronic switch module 11 locked means that the switch device (such as IGBT) is made to be open by a control signal.

[0082] Specifically, in the case of normal operation of the system, the switch tube in the mode switching module 30 can be controlled to be in an open state and the power electronic switch module 11 can be controlled to be in an open state to guarantee the normal operation of the system.

[0083] The application embodiment can ensure normal operation of the system by controlling the switch tube in the mode switching module 30 to be turned off and the power electronic switch module 11 to be blocked.

[0084] Figure 4 is another flowchart of the control method of the power electronic switch multiplexing type opening and energy consumption device provided by the application embodiment.

[0085] In some embodiments, as shown in Figure 4 The step S110 can include a step S111, in a case where the DC current is greater than the current threshold, the mode switching module 30 is used to make the power electronic switch module 11 act as the transfer branch of the DC circuit breaker 10.

[0086] S111, in a case where the DC current is greater than the current threshold, the switch tube in the mode switching module 30 is controlled to be turned on and the power electronic switch module 11 is controlled to be turned on, so that the power electronic switch module 11 acts on the transfer branch of the DC circuit breaker 10.

[0087] The DC current greater than the current threshold indicates that there is an overcurrent risk on the DC side, for example, a DC short circuit fault occurs on the DC side.

[0088] Specifically, in the case where the DC short circuit fault exists, the switch tube in the mode switching module 30 is controlled to be turned on and the power electronic switch module 11 is controlled to be turned on, so that the power electronic switch module 11 acts on the transfer branch of the DC circuit breaker 10.

[0089] In the case where the DC short circuit fault is detected, the switch tube in the mode switching module 30 is controlled to be turned on, so that the power electronic switch module 11 acts on the DC circuit breaker 10. At this time, the power electronic switch module 11 can act as the transfer branch of the DC circuit breaker 10. By controlling the power electronic switch module 11 to be turned on, the DC circuit breaker 10 can be made to act. The DC circuit breaker 10 can solve the system overcurrent problem caused by the DC line short circuit fault, and ensure safe and stable operation of the system.

[0090] In some embodiments, as shown in Figure 4 The step S120 can include a step S121, in a case where the DC voltage is greater than the voltage threshold, the mode switching module 30 is used to make the power electronic switch module 11 control the resistance in the DC energy consumer to be put into use.

[0091] S121, in a case where the DC voltage is greater than the voltage threshold, the switch tube in the mode switching module 30 is controlled to be turned off and the power electronic switch module 11 is controlled to be turned on, so that the power electronic switch module 11 controls the resistance in the DC energy consumer to be put into use.

[0092] Wherein, the DC voltage greater than the voltage threshold value indicates that there is overvoltage risk on the DC side, for example, there is a large surplus power when the AC side fails.

[0093] Specifically, in the case of AC failure, the switch tube in the control mode switching module 30 is turned off, and the power electronic switch module 11 is turned on, so that the power electronic switch module 11 can act on the DC energy consumer 20 and control the resistance in the DC energy consumer 20 to be put into use.

[0094] In the case where the application embodiment detects that there is a large surplus power when the AC fails, the switch tube in the control mode switching module 30 is turned off and the power electronic switch module 11 is turned on, so that the power electronic switch module 11 can control the resistance in the DC energy consumer to be put into use, and the DC energy consumer 20 acts to quickly absorb the surplus power generated by the receiving end AC line failure and prevent system overvoltage.

[0095] It should be noted that, Figures 2 to 4 The control method can be applied to Figure 5 The power electronic switch multiplexing type circuit breaking and energy dissipating device shown in the figure.

[0096] Figure 5 It is a structural schematic diagram of the power electronic switch multiplexing type circuit breaking and energy dissipating device provided by the application embodiment.

[0097] In some embodiments, as shown in Figure 5 The mode switching module 30 can include a first thyristor 31 and a second thyristor 32, and the first thyristor 31 and the second thyristor 32 are anti-parallel.

[0098] The power electronic switch multiplexing type circuit breaking and energy dissipating device (Multi-functional Power Electronic Switch-Based Circuit-Breaking and Energy-Dissipating Device, MPES-CED) provided by the application embodiment can multiplex the power electronic switch module 11, and in the circuit breaker mode, the power electronic switch module 11 acts as a transfer branch of the DC circuit breaker 10, and in the energy consumer mode, the power electronic switch module 11 controls the resistance to be switched, and the switching between the two modes can be realized through the thyristor switch in the mode switching module 30, thereby greatly reducing the equipment cost.

[0099] In some embodiments, can continue to refer to Figure 5 The DC circuit breaker 10 can include a power electronic switch module 11, a mechanical switch 12, an auxiliary commutation unit 13, and an energy dissipating branch 14.

[0100] Mechanical switch 12 and auxiliary converter unit 13 are connected in series between the first terminal of DC power supply 200 and the first terminal of converter 300.

[0101] The power electronic switch module 11 is electrically connected between the first terminal of the DC power supply 200 and the mode switching module 30.

[0102] The power-consuming branch 14 is electrically connected to both ends of the power electronic switch module 11.

[0103] Among them, the power-consuming branch 14 may include a metal oxide varistor (MOV).

[0104] In this embodiment, the DC circuit breaker 10 consists of a main branch (including a mechanical switch 12 and an auxiliary converter unit 13), a transfer branch (including a power electronic switch module 11), and an energy-consuming branch 14. When a DC short-circuit fault occurs, the auxiliary converter unit 13 of the main branch is disconnected, and the current is transferred to the transfer branch. When the mechanical switch 12 of the main branch is completely disconnected, the transfer branch 14 is turned off, and the residual energy is consumed by the energy-consuming branch 14.

[0105] In some embodiments, see [link to relevant documentation]. Figure 5 The DC power consumer 20 may include a power electronic switch module 11 and a DC power consumption submodule 21.

[0106] The power electronic switch module 11 is electrically connected between the first terminal of the DC power supply 200 and the mode switching module 30.

[0107] The DC power consumption submodule 21 is electrically connected between the mode switching module 30 and the second terminal of the DC power supply 200.

[0108] In this embodiment, the DC power consumer 20 is composed of a power electronic switch module 11 connected in series with a DC power consumption submodule 21. When an AC fault occurs and there is a large surplus power, the power electronic switch module 11 acts on the DC power consumer 20, and the DC power consumer 20 takes effect. The DC power consumption submodule 21 can quickly absorb the surplus power generated by the AC line fault at the receiving end and prevent system overvoltage.

[0109] In some embodiments, see [link to relevant documentation]. Figure 5 The DC power consumption submodule 21 includes an inductor 211 and a resistor 212.

[0110] Inductor 211 and resistor 212 are connected in series between the first and second terminals of DC power consumption submodule 21.

[0111] The inductor 211 can be a lumped inductor, and the inductance is concentrated at a point without considering the influence of the distributed parameters of the inductor element. The resistor 212 can be a lumped resistor, and the resistance is concentrated at a point without considering the influence of the distributed parameters.

[0112] The inductor 211 and the resistor 212 in series as the DC energy consumption submodule 21 in the embodiment of the application can quickly consume the surplus power generated by the AC line fault at the receiving end in the case of a large surplus power in the AC fault, and prevent system overvoltage.

[0113] In some embodiments, the inductance of the inductor 211 is k times the equivalent inductance, and k is greater than or equal to 3 and less than or equal to 5. The equivalent inductance satisfies the following formula:

[0114]

[0115] where ΔU max is the maximum DC voltage ripple requirement, ΔU dc1 is the voltage ripple generated by the power electronic action frequency, ΔU dc2 is the voltage ripple generated by the current impact on the inductor, I rate is the rated DC current, C eq is the equivalent capacitance, f S is the frequency of switching action in the power electronic switching module 11, L eq is the equivalent inductance, I R is the current of the resistor, and t is time.

[0116] It should be noted that the power electronic switching multiplexing type breaking and energy consumption device needs to consider the DC voltage ripple ΔU max requirement, and the maximum DC voltage ripple is determined by the voltage ripple ΔU dc1 generated by the power electronic action frequency and the voltage ripple ΔU dc2 generated by the current impact on the inductor.

[0117] The parameters in the above formula are known parameters except for the equivalent inductance L eq , so the value of the action frequency (the value of the equivalent inductance L eq ) can be solved according to the above formula, and the inductance value of the inductor 211 can be solved according to the equivalent inductance L eq .

[0118] The inductor 211 mainly reduces the influence of ΔU dc2 , and the larger the inductor 211 is, the smaller ΔU dc2 is. Considering the economic requirement, the inductor 211 can be selected to be 3 to 5 times the size of the system equivalent inductance L eq , so the value of k can be greater than or equal to 3 and less than or equal to 5.

[0119] The inductance value of the inductor 211 can be quickly calculated by the formula, so that the power electronic switch multiplexing type breaking-energy consumption device can meet the DC voltage ripple ΔU max requirements.

[0120] In some embodiments, the resistance value of the resistor 212 satisfies the following formula:

[0121]

[0122] wherein R is the resistance value of the resistor 212, U dc is the DC voltage, and P rate is the rated power.

[0123] The resistance value of the resistor 212 is set based on the principle of power matching, so that the resistor 212 can accommodate the rated power of the system under a given DC voltage, to cope with the surplus power problem under serious working conditions such as three-phase short circuit.

[0124] Under the most serious three-phase short circuit working condition, the power electronic switch multiplexing type breaking-energy consumption device can ensure that the resistor 212 can accommodate the rated power of the system when facing the surplus power consumption of the AC fault.

[0125] In one example, referring to Figure 5 , the power electronic switch multiplexing type breaking-energy consumption device 100 can include a power electronic switch module 11, a mechanical switch 12, an auxiliary commutation unit 13, an energy consumption branch 14, a mode switching module 30 (composed of two anti-parallel thyristor switches), a centralized inductor 211, and a centralized resistor 212.

[0126] The auxiliary commutation unit 13 can include four IGBTs, one capacitor, and two diodes, the mode switching module 30 is composed of two anti-parallel thyristors, and the power electronic switch module 11 is composed of a plurality of sub-modules connected in series, each sub-module including five diodes, two IGBTs, and one capacitor. To ensure the reliable operation of the power electronic device, the number N of sub-modules is determined by the following formula.

[0127] N = round up (1.5U dc / U SM )

[0128] wherein U dc is the DC voltage, U SM is the rated voltage that can be withstood by a single sub-module, and round up means rounding up.

[0129] The number of sub-modules can be determined according to the direct-current voltage and the rated voltage of the sub-modules in the power electronic switching module 11, the system requirement can be accurately matched, and the reliable work of the power electronic device is ensured.

[0130] Based on the same inventive concept, please continue to refer to Figure 1 or Figure 5 The embodiment of the application further provides a power electronic switching multiplexing type breaking-energy consumption device 100, which can include the direct-current circuit breaker 10 and the direct-current energy consumption device 20.

[0131] The direct-current circuit breaker 10 is electrically connected between the first end of the direct-current power supply 200 and the first end of the converter 300.

[0132] The direct-current energy consumption device 20 is electrically connected between the two ends of the direct-current power supply 200, wherein the direct-current circuit breaker 10 and the direct-current energy consumption device 20 include the same power electronic switching module 11.

[0133] The mode switching module 30 is electrically connected between the power electronic switching module 11 and the first end of the converter 300.

[0134] The mode switching module 30 is configured to:

[0135] In the case that the direct-current is greater than the current threshold, the power electronic switching module 11 is used as a transfer branch of the direct-current circuit breaker 10.

[0136] In the case that the direct-current voltage is greater than the voltage threshold, the power electronic switching module 11 controls the resistance in the direct-current energy consumption module 20 to be put into use.

[0137] The power electronic switch multiplexed breaking-energy consumption device provided by the embodiment of the present application. The power electronic switch multiplexed breaking-energy consumption device comprises a direct current circuit breaker, a direct current energy consumer and a mode switching module. The direct current circuit breaker is electrically connected between the first end of a direct current power supply and the first end of a converter; the direct current energy consumer is electrically connected between the two ends of the direct current power supply, wherein the direct current circuit breaker and the direct current energy consumer comprise the same power electronic switch module. The mode switching module is electrically connected between the power electronic switch module and the first end of the converter. In the case that the direct current is greater than a current threshold value, the power electronic switch module can be used as a transfer branch of the direct current circuit breaker by the mode switching module, which can effectively deal with the system overcurrent problem caused by the short circuit fault of the direct current line, and ensure the safe and stable operation of the system. In the case that the direct current voltage is greater than a voltage threshold value, the mode switching module can be used to make the resistance in the direct current energy consumer put into use, which can quickly consume the excess power generated by the receiving end AC line fault and prevent the system from overvoltage. By integrating the direct current circuit breaker and the direct current energy consumer and multiplexing the power electronic switch module, the functions of breaking the short circuit current of the direct current under fault and switching the resistance can be realized at the same time, and the cost and size of the device can be greatly saved.

[0138] In one example, reference can be made to Figure 6 , U dc is the voltage on the system direct current bus, U dccb is the voltage across the direct current circuit breaker 10, specifically the voltage between the left side of the mechanical switch 12 and the right side of the auxiliary converter unit 13. When a short circuit fault occurs on the system direct current side (the direct current is greater than the current threshold value), the power electronic switch multiplexed breaking-energy consumption device 100 uses the mode switching module 30 to make the power electronic switch module 11 work as a transfer branch of the direct current circuit breaker 10 (the switch tube in the mode switching module 30 is turned on, and the power electronic switch module 11 is turned on, so that the power electronic switch module 11 acts on the transfer branch of the direct current circuit breaker 10). The working principle is as follows:

[0139] Before t0, the system is in normal operation, the mechanical switch 12 is closed, the IGBT in the auxiliary converter unit 13 is turned on, and the direct current I dc flows through the IGBT in the auxiliary converter unit 13, the thyristor switch in the control mode switching module 30 is turned off, and the power electronic switch module 11 is blocked.

[0140] At t0, a short circuit fault occurs on the direct current side, the direct current voltage drops to 0, and the direct current rises.

[0141] At t1, it is detected that the direct current I dcWhen the set upper limit value is exceeded (the direct current is greater than the current threshold value), the switch tube IGBT in the auxiliary commutation unit 13 is turned off, the mechanical switch 12 receives a tripping instruction, and the thyristor switch in the power electronic switch module 11 and the mode switching module 30 is turned on, and the current is transferred to the branch where the power electronic switch module 11 is located.

[0142] At t2, after the mechanical switch 12 is completely turned off, the power electronic switch module 11 starts to be turned off, the current is transferred to the metal oxide varistor (MOV) on the energy dissipation branch 14, the voltage on the MOV is established, and then the thyristor current zero-crossing in the mode switching module 30 is turned off.

[0143] At t3, the current on the power electronic switch module 11 is reduced to 0, and then when the fault is cleared, the mechanical switch 12 is reclosed and the auxiliary commutation unit 13 is turned on again.

[0144] The scheme of integrating the direct current circuit breaker and the direct current energy dissipator proposed in the embodiments of the present application can greatly save the device cost and volume by multiplexing the power electronic switch module, and in the circuit breaker mode (in the case that the direct current is greater than the current threshold value), the power electronic switch module can effectively cope with the system overcurrent problem caused by the short-circuit fault of the direct current line and guarantee the safe and stable operation of the system.

[0145] In one example, referring to Figure 7 When a short-circuit fault occurs on the alternating current side and the direct current voltage is greater than the voltage threshold value, the working principle of the power electronic switch multiplexing type breaking-energy dissipating device 100 in which the power electronic switch module 11 is used as the transfer branch of the direct current circuit breaker 10 (the switch tube in the mode switching module 30 is turned off and the power electronic switch module 11 is turned on, so that the power electronic switch module 11 controls the resistance 212 in the direct current energy dissipator 20 to be put into use) is as follows:

[0146] Before t0, the system is in normal operation, the mechanical switch 12 is closed, the IGBT in the auxiliary commutation unit 13 is turned on, the direct current I dc The switch tube IGBT in the auxiliary commutation unit 13 is passed through, the thyristor switch in the control mode switching module 30 is turned off, and the power electronic switch module 11 is controlled to be blocked.

[0147] At t0, a short-circuit fault occurs on the alternating current side, the system has surplus power, and the direct current voltage continues to rise.

[0148] At t1, when it is detected that the direct current voltage exceeds the set upper limit value (the direct current voltage is greater than or equal to the voltage threshold value), the power electronic switch module 11 is turned on, the current flows through the resistance 212 in the direct current energy dissipator 20, energy dissipation is started, and the direct current voltage is reduced.

[0149] At time t2, when it is detected that the DC voltage is lower than the set lower limit value (the DC voltage is less than the voltage threshold value), the power electronic switch module 11 is controlled to be turned off, the resistor 212 stops consuming energy, and the DC voltage rises. The above process is repeated thereafter, so that the DC voltage is stabilized within a certain range.

[0150] At time t3, the fault ends, the power electronic switch module 11 is controlled to be locked, and then the system DC voltage returns to its rated value.

[0151] The scheme of integrating the DC circuit breaker and the DC energy consumer proposed in the embodiments of the present application can greatly save the device cost and volume by multiplexing the power electronic switch module, and the power electronic switch module can control the switching of the resistor in the DC energy consumer mode, so as to quickly absorb the surplus power generated by the receiving end AC line fault and prevent system overvoltage.

[0152] It should be noted that the power electronic switch multiplexing type breaking-energy device proposed in the embodiments of the present application can be applied to offshore wind power grid-connected systems, onshore wind power grid-connected systems, large-scale photovoltaic grid-connected systems, etc. When a DC short-circuit fault occurs at the DC side of the system, the power electronic switch multiplexing type breaking-energy device can break the short-circuit current to realize fault ride-through; when a low-voltage fault or a DC short-circuit fault occurs at the AC side of the system, the power electronic switch multiplexing type breaking-energy device can effectively dissipate the surplus power of the system to maintain the stability of the system DC voltage.

[0153] Based on the same inventive concept, as shown in Figure 8 The embodiments of the present application also provide a new energy sending system 1000, which comprises a DC power source 200, a converter 300, a controller 400 and a power electronic switch multiplexing type breaking-energy device 100. The controller is used to execute the method described in any of the above embodiments.

[0154] Figure 8 In the embodiments, the DC power source 200 is a rectifier, and the rectifier uses the structure of a modular multilevel converter (MMC), that is, the modular multilevel converter (MMC) is used as the rectifier. The converter 300 is an inverter, and the inverter uses the structure of a modular multilevel converter (MMC), that is, the modular multilevel converter (MMC) is used as the inverter.

[0155] The new energy sending-out system 1000 comprises the power electronic switch multiplexing type breaking-energy consuming device 100 provided in any of the above embodiments, and thus has all the beneficial effects of the power electronic switch multiplexing type breaking-energy consuming device 100.

[0156] It should be understood that, in the embodiments of the present application, "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should also be understood that the determination of B according to A does not mean that B is determined only according to A, but B can also be determined according to A and / or other information.

[0157] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A control method of a power electronic switch multiplexed break- energy dissipation device, characterized by, The power electronic switch multiplexed breaking-energy consuming device comprises: a direct current circuit breaker electrically connected between a first end of a direct current power supply and a first end of a converter; a direct current energy consumer electrically connected between two ends of the direct current power supply, wherein the direct current circuit breaker and the direct current energy consumer comprise a same power electronic switch module; a mode switching module electrically connected between the power electronic switch module and the first end of the converter; The method comprises: in a case where a direct current is greater than a current threshold, using the mode switching module to make the power electronic switch module act as a transfer branch of the direct current circuit breaker; in a case where a direct current voltage is greater than a voltage threshold, using the mode switching module to make the power electronic switch module control a resistance in the direct current energy consumer to be put into use.

2. The method of claim 1, wherein, The mode switching module comprises a switch tube; the method further comprises: in a case of normal operation, controlling the switch tube in the mode switching module to be turned off and the power electronic switch module to be blocked; and / or, in the case where the direct current is greater than the current threshold, using the mode switching module to make the power electronic switch module act as the transfer branch of the direct current circuit breaker, comprising: in the case where the direct current is greater than the current threshold, controlling the switch tube in the mode switching module to be turned on and the power electronic switch module to be turned on, so that the power electronic switch module acts on the transfer branch of the direct current circuit breaker; and / or, in the case where the direct current voltage is greater than the voltage threshold, using the mode switching module to make the power electronic switch module control the resistance in the direct current energy consumer to be put into use, comprising: in the case where the direct current voltage is greater than the voltage threshold, controlling the switch tube in the mode switching module to be turned off and the power electronic switch module to be turned on, so that the power electronic switch module controls the resistance in the direct current energy consumer to be put into use.

3. The method of claim 2, wherein, The mode switching module comprises a first thyristor and a second thyristor, which are anti-parallel connected.

4. The method of claim 1, wherein, The direct current circuit breaker comprises: a mechanical switch and an auxiliary converter unit connected in series between the first end of the direct current power supply and the first end of the converter; the power electronic switch module electrically connected between the first end of the direct current power supply and the mode switching module; an energy consuming branch electrically connected between two ends of the power electronic switch module.

5. The method of claim 1, wherein, The direct current energy consumer comprises: the power electronic switch module electrically connected between the first end of the direct current power supply and the mode switching module; a direct current energy sub-module electrically connected between the mode switching module and a second end of the direct current power supply.

6. The method of claim 5, wherein, The direct current energy sub-module comprises an inductor and a resistor: the inductor and the resistor are connected in series between a first end and a second end of the direct current energy sub-module.

7. The method of claim 6, wherein, An inductance value of the inductor is k times of an equivalent inductance, k is greater than or equal to 3 and less than or equal to 5; the equivalent inductance satisfies the following formula: where ΔU max is the DC voltage ripple demand, ΔU dc1 is the voltage ripple due to power electronic action frequency, ΔU dc2 is the voltage ripple due to current impact on inductance, I rate is the rated DC current, C eq is the equivalent capacitance, f S is the frequency of switching action in the power electronic switching module, L eq is the equivalent inductance, I R is the current through the resistor, t is time.

8. The method of claim 6, wherein, a resistance value of the resistor satisfies the following formula: wherein said R is the resistance value of said resistance, said U dc is a direct current voltage, said P rate is the rated power.

9. A power electronic switch multiplexed opening-dissipating device, characterized by, The power electronic switch multiplexed breaking-energy consuming device comprises: a direct current circuit breaker electrically connected between a first end of a direct current power supply and a first end of a converter; a DC energy consumer electrically connected between two terminals of the DC power source, wherein the DC circuit breaker and the DC energy consumer comprise one and the same power electronic switch module; a mode switching module electrically connected between the power electronic switch module and the first terminal of the converter; wherein the mode switching module is configured to: in case the DC current is greater than a current threshold, cause the power electronic switch module to act as a transfer branch of the DC circuit breaker; in case the DC voltage is greater than a voltage threshold, cause the power electronic switch module to control a resistance in the DC energy consumer to be put into use.

10. A new energy sending-out system characterized by comprising: a DC power source, a converter, a controller, and a power electronic switch multiplexed opening- energy consuming device, the controller being configured to perform the method of any one of claims 1 to 8.

Images