A control method of a sub-module-based offshore wind power direct-current energy dissipation device

Abstract

The application discloses a control method of an offshore wind power direct-current energy consumption device based on a sub-module, wherein the device comprises an energy consumption valve and an energy consumption resistor connected in series with the energy consumption valve; the energy consumption valve comprises a plurality of switch sub-modules connected in series; the switch sub-module comprises a first power switch tube, a second power switch tube, an anti-reverse diode, an absorption capacitor and a discharge resistor; the drain electrode of the first power switch tube is connected with the anode of the anti-reverse diode, the source electrode of the first power switch tube is connected with one end of the discharge resistor, the cathode of the anti-reverse diode is connected with the source electrode of the second power switch tube, the drain electrode of the second power switch tube is connected with the other end of the discharge resistor, one end of the absorption capacitor is connected with the cathode of the anti-reverse diode, and the other end of the absorption capacitor is connected with the source electrode of the first power switch tube; and the second power switch tube is used for controlling the absorption capacitor to release energy to the discharge resistor. The application can effectively improve the operation stability of the offshore wind power direct-current energy consumption device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, in particular to a control method of an offshore wind power DC energy consumption device based on sub-modules. BACKGROUND

[0002] Flexible DC transmission system is widely used in offshore wind power DC transmission system due to its low line loss, independent control of active and reactive power, and effective solution to the problem of weak AC wind turbine system grid connection. Due to the characteristics of long response time and large inertia of wind turbine, when the load at the use end is unloaded or the fault occurs at the land converter station, the system will have surplus power, which will cause the DC bus voltage to rise, which is not conducive to the safe and stable operation of the DC transmission system. It is usually necessary to set up a corresponding offshore wind power DC energy consumption device at the land end of the DC transmission line to dissipate the system surplus power, balance the system power, and maintain the stability of the DC voltage.

[0003] The existing offshore wind power DC energy consumption device is usually composed of a plurality of power switch tubes in series combined with a centralized energy consumption resistor. The PWM modulation method is used to control all the series power switch tubes to act simultaneously, and the size of the energy consumption power of the offshore wind power DC energy consumption device is changed by adjusting the duty cycle of the power switch period. However, the existing offshore wind power DC energy consumption device needs to withstand a large voltage and current impact during operation, and is prone to cause large fluctuations in DC transmission voltage, resulting in unstable operation of the offshore wind power DC energy consumption device. SUMMARY

[0004] The present application provides a control method of an offshore wind power DC energy consumption device based on sub-modules to solve the technical problem that the existing offshore wind power DC energy consumption device needs to withstand a large voltage and current impact during operation, and is prone to cause large fluctuations in DC transmission voltage, resulting in unstable operation of the offshore wind power DC energy consumption device.

[0005] One embodiment of the present application provides an offshore wind power DC energy consumption device based on sub-modules, comprising:

[0006] An energy consumption valve and an energy consumption resistor connected in series with the energy consumption valve;

[0007] The energy consumption valve comprises a plurality of switch sub-modules, and the plurality of switch sub-modules are connected in series;

[0008] The switch sub-module comprises a first power switch tube, a second power switch tube, an anti-reverse diode, an absorption capacitor and a discharge resistor;

[0009] The drain electrode of the first power switch tube is connected with the anode of the anti-reverse diode, the source electrode of the first power switch tube is connected with one end of the discharge resistor, the cathode of the anti-reverse diode is connected with the source electrode of the second power switch tube, the drain electrode of the second power switch tube is connected with the other end of the discharge resistor, one end of the absorption capacitor is connected with the cathode of the anti-reverse diode, and the other end of the absorption capacitor is connected with the source electrode of the first power switch tube.

[0010] The first power switch tube is used for controlling the input and output state of the switching sub-module.

[0011] The second power switch tube is used for controlling the energy release of the absorption capacitor to the discharge resistor.

[0012] The anti-reverse diode is used for preventing the energy in the absorption capacitor from being released to the direct-current bus.

[0013] The absorption capacitor is used for supporting the voltage of the switching sub-module and absorbing the surplus impact power of the system.

[0014] The discharge resistor is used for releasing the energy in the absorption capacitor.

[0015] One embodiment of the present application provides a control method of a sub-module-based offshore wind power direct-current energy consumption device, which is suitable for the offshore wind power direct-current energy consumption device and comprises the following steps.

[0016] During the working of the offshore wind power direct-current energy consumption device, the surplus power of the system is acquired.

[0017] According to the surplus power of the system, the input and output state of the switching sub-module is controlled.

[0018] Further, the step of controlling the input and output state of the switching sub-module according to the surplus power of the system comprises the following steps.

[0019] When the surplus power of the system is within a preset range, the input and output state of the switching sub-module is controlled by a grouping step-by-step mode, so that the energy consumption power matches the surplus power of the system.

[0020] When the surplus power of the system exceeds the preset range, the second power switch tube is controlled to be turned on, the discharge resistor is connected to both ends of the absorption capacitor, so that the energy consumption power matches the surplus power of the system.

[0021] Further, the step of controlling the input and output state of the switching sub-module by a grouping step-by-step mode comprises the following steps.

[0022] The input and output state of the switching module is controlled by a grouping step-by-step mode, and the surplus power of the system is divided into several parts.

[0023] Further, the control of the opening of the second power switch tube includes:

[0024] According to the voltage balance relationship of the offshore wind power DC energy consumption device, the opening time of the second power switch tube is controlled.

[0025] The voltage balance relationship includes:

[0026] U dc = U sm + U R

[0027] In the formula, U dc is the voltage across the DC transmission line, U sm is the voltage across the energy consumption valve, and U R is the voltage across the concentrated energy consumption resistor.

[0028] Further, the control of the opening of the second power switch tube includes:

[0029] According to the system power balance relationship of the offshore wind power DC energy consumption device, the opening time of the second power switch tube is controlled.

[0030] The system power balance relationship includes:

[0031] p extra = p R + p r

[0032] In the formula, p extra is the system surplus power, p R is the energy consumption power of the energy consumption resistor, and p r is the dissipation power of the discharge resistor.

[0033] One embodiment of the present application provides a control device of an offshore wind power DC energy consumption device based on a sub-module, including:

[0034] A system surplus power acquisition module is configured to acquire system surplus power during the operation of the offshore wind power DC energy consumption device.

[0035] A switch sub-module switching state control module is configured to control the switching in and out state of the switch sub-module according to the system surplus power.

[0036] One embodiment of the present application provides a computer readable storage medium including a stored computer program, wherein when the computer program is running, the device where the computer readable storage medium is located performs the control method of the offshore wind power DC energy consumption device based on a sub-module as described above.

[0037] In the embodiment of the present application, by arranging the second power switch tube and the discharge resistor in the switch sub-module, when the system surplus power is too high to cause the DC bus voltage to drop to the steady state value, the excess energy of the absorption capacitor is released by controlling the second power switch tube and the discharge resistor to work together, so as to reduce the voltage across the absorption capacitor, thereby reducing the DC bus voltage to the steady state value, improving the stability of the offshore wind power DC energy consumption device operation, and by arranging and regulating the first power switch tube and the second power switch tube, the balance of the capacitor voltage of each switch sub-module can be effectively adjusted.

[0038] Further, in the embodiment of the present application, when the system energy consumption power changes in steps during the operation of the offshore wind power DC energy consumption device, the stepwise switching control can be performed according to the grouping of the switch sub-modules, so as to effectively suppress the impact of the step change of the system surplus power on the system, and in the embodiment of the present application, the switch sub-modules are controlled based on the system surplus power, when the system surplus power is too low, the voltage division of the energy consumption valve can be controlled by adjusting the number of switch sub-modules put in and out, so as to dynamically adjust the voltage across the energy consumption resistor; when the system surplus power is too high, the DC transmission line voltage rises, the energy of the switch sub-module absorption capacitor is excessive, the voltage across the switch sub-module absorption capacitor exceeds the steady state value, at this time, the energy in the switch sub-module absorption capacitor is released through the discharge resistor by controlling the turn-on of the second power switch tube, so as to effectively reduce the voltage across the switch sub-module absorption capacitor, thereby effectively maintaining the stability of the DC transmission line voltage and balancing the system power. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a structural schematic diagram of the offshore wind power DC energy consumption device based on the sub-module provided by the embodiment of the present application;

[0040] Figure 2 is a flowchart of the control method of the offshore wind power DC energy consumption device based on the sub-module provided by the embodiment of the present application;

[0041] Figure 3 is a switch sub-module put-out state schematic diagram of the offshore wind power DC energy consumption device based on the sub-module provided by the embodiment of the present application;

[0042] Figure 4 is a switch sub-module put-in state schematic diagram of the offshore wind power DC energy consumption device based on the sub-module provided by the embodiment of the present application;

[0043] Figure 5 is a schematic diagram of the discharge of the energy of the absorption capacitor in the switch sub-module of the offshore wind power DC energy consumption device based on the sub-module provided by the embodiment of the present application;

[0044] Figure 6is a grouping schematic diagram of the sub-module grouping step switching control switch of the offshore wind power DC energy dissipation device provided by the embodiment of the present application.

[0045] Figure 7 is a DC voltage change curve schematic diagram of the offshore wind power DC energy dissipation device before and after the action when the system surplus power is 500kW;

[0046] Figure 8 is a switch sub-module capacitor voltage change curve schematic diagram of the offshore wind power DC energy dissipation device before and after the action when the system surplus power is 500kW;

[0047] Figure 9 is a structure schematic diagram of the control device of the offshore wind power DC energy dissipation device based on the sub-module provided by the embodiment of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0049] In the description of the present application, it should be understood that the terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0050] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0051] Please refer to Figure 1 An embodiment of the present application provides a sub-module-based offshore wind power DC energy dissipation device, comprising:

[0052] The energy dissipation valve 10 and the energy dissipation resistor 20 connected in series with the energy dissipation valve 10;

[0053] The energy consumption valve 10 comprises a plurality of switch sub-modules 11 connected in series.

[0054] The switch sub-module 11 comprises a first power switch tube 111, a second power switch tube 112, an anti-reverse diode 113, an absorption capacitor 114 and a discharge resistor 115.

[0055] The drain electrode of the first power switch tube 111 is connected with the anode of the anti-reverse diode 113, the source electrode of the first power switch tube 111 is connected with one end of the discharge resistor 115, the cathode of the anti-reverse diode 113 is connected with the source electrode of the second power switch tube 112, the drain electrode of the second power switch tube 112 is connected with the other end of the discharge resistor 115, one end of the absorption capacitor 114 is connected with the cathode of the anti-reverse diode 113, and the other end of the absorption capacitor 114 is connected with the source electrode of the first power switch tube 111.

[0056] The first power switch tube 111 is used for controlling the input and output state of the switch sub-module 11.

[0057] The second power switch tube 112 is used for controlling the absorption capacitor 114 to release energy to the discharge resistor 115.

[0058] The anti-reverse diode 113 is used for preventing the energy in the absorption capacitor 114 from being released to the direct-current bus.

[0059] The absorption capacitor 114 is used for supporting the voltage of the switch sub-module 11 and absorbing surplus impact power of the system.

[0060] The discharge resistor 115 is used for releasing the energy in the absorption capacitor 114.

[0061] In the embodiment of the present application, Figure 1 SM1, SM2, SM3, …, SM6 in the formula are switch sub-modules 11, and in the embodiment of the present application, the second power switch tube 112 and the discharge resistor 115 are arranged in the switch sub-module 11, when the direct-current bus voltage is reduced to the steady-state value due to the excessively high system surplus power, the over-energized absorption capacitor 114 releases the energy to reduce the voltage across the capacitor through the joint action of the second power switch tube 112 and the discharge resistor 115, thereby reducing the direct-current bus voltage to the steady-state value, improving the stability of the offshore wind power direct-current energy consumption device, and through the arrangement and control of the first power switch tube 111 and the second power switch tube 112, the capacitor voltage of each switch sub-module 11 can be effectively adjusted.

[0062] Please refer to Figure 2 An embodiment of the present application provides a control method of an offshore wind power direct-current energy consumption device based on a sub-module, which is suitable for the offshore wind power direct-current energy consumption device based on a sub-module and comprises the following steps.

[0063] S1, during the operation of the offshore wind power DC energy consumption device, acquiring system surplus power;

[0064] In the embodiment of the present application, the wind turbine power and load demand power data during the operation of the offshore wind power transmission system can be counted to calculate the system surplus power.

[0065] S2, according to the system surplus power, controlling the input and output state of the switch sub-module 11.

[0066] In the embodiment of the present application, based on the system surplus power, the input and output state of the switch sub-module 11 is controlled. When the system surplus power is too low, the voltage division of the energy consumption valve 10 can be controlled by adjusting the number of switch sub-modules 11 put into or taken out, so as to dynamically adjust the voltage across the energy consumption resistor 20. When the system surplus power is too high, the DC transmission line voltage rises, the switch sub-module 11 absorbs the energy of the capacitor 114, and the voltage across the switch sub-module 11 exceeds the steady state value. At this time, the energy in the switch sub-module 11 absorbing capacitor 114 is released through the discharge resistor 115 by controlling the opening of the second power switch tube 112, so as to effectively reduce the voltage across the sub-module absorbing capacitor 114, and further effectively maintain the stability of the DC transmission line voltage and balance the system power.

[0067] In the embodiment of the present application, according to the system surplus power, the input and output state of the switch sub-module 11 is controlled, including:

[0068] When the system surplus power is in the preset range, the input and output state of the switch sub-module 11 is controlled in a grouped step-by-step manner, so that the energy consumption power matches the system surplus power.

[0069] In the embodiment of the present application, when the system surplus power is in the preset range, it is judged that the system surplus power is too low. The input and output state of the switch sub-module 11 can be controlled to stabilize the DC bus voltage and balance the energy consumption power on the energy consumption resistor 20 and the system surplus power.

[0070] In one embodiment, the voltage division of the energy consumption valve 10 is u sm , u sm =n sm ·U CN , n sm is the number of switch sub-modules 11 put into the energy consumption valve 10, U CN is the steady state voltage value of the switch sub-module 11 absorbing capacitor 114, at this time u dc =u sm +u R =u dcN , u dc is the DC voltage, and u smu is the control voltage of the energy consumption valve 10 R U is the voltage across the energy consumption resistor 20 dcN p is the direct current steady voltage extra p is the system surplus power R P is the energy consumption power

[0071] When the system surplus power exceeds the preset range, the second power switch tube 112 is controlled to be turned on, and the flood discharge resistor is connected across the absorbing capacitor 114, so that the energy consumption power matches the system surplus power.

[0072] In the embodiment of the application, when the system surplus power exceeds the preset range, it is judged that the system surplus power is too high, at this time, the direct current voltage rises, u dc >U dcN , and the corresponding capacitor voltage is also higher than the steady value u C >U CN , u C is the voltage of the absorbing capacitor 114, at this time, the second power switch tube 112 in the control switch sub-module 11 needs to be controlled to be turned on, so that the discharge resistor 115 is connected across the absorbing capacitor 114, thereby releasing the energy in the absorbing capacitor 114, and further reducing the voltage across the absorbing capacitor 114, and further reducing the direct current bus voltage, so as to maintain the stability of the direct current voltage, at this time, the system surplus power is shared by the centralized energy consumption resistor 20 and the distributed energy consumption resistor 20, p extra =p R +p r , p r is the power dissipated by the distributed energy consumption resistor 20.

[0073] In one embodiment, the input and output states of the switch sub-module 11 are controlled in a grouped step-by-step manner, including:

[0074] The input and output states of the switch module are controlled in a grouped step-by-step manner, and the system surplus power is divided into several parts.

[0075] In the embodiment of the application, the system surplus power can be divided into k parts:

[0076] P extra =P1+P2+…+P k

[0077] In the embodiment of the application, by dividing the system surplus power into k parts, the step change size of the surplus power can be effectively reduced, thereby reducing the power impact on the system and suppressing the overshoot of the direct current bus voltage, thereby effectively improving the stability of the direct current bus voltage.

[0078] In one embodiment, the second power switch tube 112 is controlled to be turned on, including:

[0079] According to the voltage balance relationship of the offshore wind power DC energy consumption device, the opening time of the second power switch tube 112 is controlled;

[0080] The voltage balance relationship includes:

[0081] U dc = U sm + U R

[0082] In the formula, U dc is the voltage across the DC outgoing line, U sm is the voltage across the energy consumption valve 10, and U R is the voltage across the concentrated energy consumption resistor 20.

[0083] In the embodiment of the present application, by controlling the opening time of the second power switch tube 112, the energy in the absorption capacitor 114 is released, and the capacitor voltage in the switch sub-module 11 is controlled to be equal in size, so that the capacitor voltage of each switch sub-module 11 is balanced, and the voltage balance relationship is satisfied.

[0084] In one embodiment, controlling the opening of the second power switch tube 112 also includes:

[0085] According to the system power balance relationship of the offshore wind power DC energy consumption device, the opening time of the second power switch tube 112 is controlled;

[0086] The system power balance relationship includes:

[0087] p extra = p R + p r

[0088] In the formula, p extra is the system surplus power, p R is the energy consumption power of the energy consumption resistor 20, and p r is the dissipation power of the discharge resistor 115.

[0089] In the embodiment of the present application, when the system surplus power exceeds the preset range, the DC bus voltage rises and is not controlled by the energy consumption valve 10, and the voltage across the absorption capacitor 114 is higher than the steady state value. The embodiment of the present application can control the discharge capacitor to be connected across the absorption capacitor 114 through the second power switch tube 112 to release the energy of the absorption capacitor 114, thereby reducing the voltage across the absorption capacitor 114, thereby balancing the system surplus power and maintaining the stability of the DC bus voltage.

[0090] In one embodiment, in order to ensure that the capacitor voltage of the switching sub-module 11 of the energy consumption valve 10 is balanced during the operation of the offshore wind power DC energy consumption device, the power switch tube in the switching sub-module 11 can be controlled to adjust the capacitor voltage of the switching sub-module 11, wherein the turn-on of the first power switch tube 111 can be controlled to charge the absorption capacitor 114, and the turn-on of the second power switch tube 112 can be controlled to discharge the absorption capacitor 114, that is, the embodiment of the present application can precisely control the voltage across the absorption capacitor 114 by coordinating the turn-on time of the first power switch tube 111 and the second power switch tube 112, so that the capacitor voltage of each switching sub-module 11 can be kept balanced.

[0091] Please refer to Figure 3 , the switching sub-module 11 provided by the embodiment of the present application is in the state of being put out, Figure 4 , the switching sub-module 11 provided by the embodiment of the present application is in the state of being put in.

[0092] When the switching sub-module 11 is in the state of being put out, the first power switch tube 111 is turned on, the voltage division of the switching sub-module 11 is zero, and the absorption capacitor 114 does not absorb system power at this time, and the absorption capacitor 114 can release energy through the second power switch tube 112 according to needs; when the switching sub-module 11 is in the state of being put in, the first power switch tube 111 is turned off, the sub-module provides voltage support, and the voltage size is equal to the voltage across the absorption capacitor 114, at this time the second power switch tube 112 is turned off. The size of the energy stored by the capacitor depends on the capacitance value and the capacitor voltage size, and the expression is: E C The energy stored by the capacitor, C is the capacitance value, U C is the capacitor voltage. During the operation of the offshore wind power DC energy consumption device, when the system surplus power is small, the number of switching sub-modules 11 in the energy consumption valve 10 is adjusted to control the voltage division of the energy consumption valve 10, so as to dynamically adjust the voltage across the energy consumption resistor 20, and then change the size of the energy consumption power on the energy consumption resistor 20, so that the energy consumption power matches the system surplus power, and at the same time the stability of the DC transmission line voltage can be maintained.

[0093] When the system surplus power is too low, the DC voltage will not be raised, and the embodiment of the present application can modulate the switching sub-module 11 of the energy consumption valve 10 to keep the DC voltage stable and match the system surplus power with the energy consumption power, at this time the voltage balance relationship is: dc u sm +u R =U dcN , and the power balance relationship is:

[0094] When the system surplus power is too high, the DC transmission line voltage rises, the energy of the absorption capacitor 114 of the switching submodule 11 is excessive, the voltage of the absorption capacitor 114 of the submodule exceeds the steady-state value, and the embodiment of the application can control the turn-on of the second power switch tube 112 to make the energy in the absorption capacitor 114 of the switching submodule 11 be released through the discharge resistor 115, thereby effectively reducing the voltage of the absorption capacitor 114 of the submodule, and further reducing the DC transmission line voltage. The reasonable release of the energy of the absorption capacitor 114 can also provide an energy space for the surplus power of the next offshore wind power DC energy consumption device to be buffered by the submodule capacitor. At this time, the system power balance relationship is: p extra = p R + p r .

[0095] Please refer to Figure 5 , the embodiment of the application provides an energy discharge schematic diagram of the absorption capacitor 114 in the switching submodule 11 of the offshore wind power DC energy consumption device based on a submodule.

[0096] In the surplus power matching control, the embodiment of the application adopts the switching submodule 11 grouping stepwise switching mode for adjustment, so that the influence of the step change of the system surplus power on the power impact of the system can be reduced. Specifically, the energy consumption valve 10 submodule can be divided into k groups, each group contains a submodule, and the grouping situation can be flexibly adjusted according to actual needs.

[0097] Please refer to Figure 6 , the embodiment of the application provides a grouping schematic diagram of the switching submodule 11 of the offshore wind power DC energy consumption device based on a submodule.

[0098] In one embodiment, the embodiment of the application can build a corresponding model in PSCAD for simulation according to the above offshore wind power DC energy consumption device and control strategy. Specifically, the rated DC bus voltage is set to 100kV, the rated operating power is set to 1000kW, and 10 submodules are connected in series in the energy consumption valve 10.

[0099] Please refer to Figure 7 and Figure 8 , the results before and after the offshore wind power DC energy consumption device in the embodiment of the application when the system surplus power is 500kW. Before the energy consumption device acts, the DC bus voltage rises to 162kV at most, and the capacitor voltage of the switching submodule 11 rises to 17V at most; after the offshore wind power DC energy consumption device acts, the DC bus voltage quickly drops to 100kV, and the over-energized energy of the switching submodule 11 capacitor is released through the discharge resistor 115 by controlling the second power switch tube 112, and the capacitor voltage of the switching submodule 11 can quickly recover to the steady-state value of 10kV.

[0100] Please refer toFigure 9 Based on the same inventive concept as the above embodiments, one embodiment of the present application provides a control device of a sub-module-based offshore wind power DC energy consumption device, comprising:

[0101] The system surplus power acquisition module 101 is configured to acquire system surplus power during operation of the offshore wind power DC energy consumption device.

[0102] The switch sub-module 11 switching state control module 201 is configured to control the switching-in and switching-out state of the switch sub-module 11 according to the system surplus power.

[0103] In one embodiment, the switching-in and switching-out state of the switch sub-module 11 is controlled according to the system surplus power, including:

[0104] When the system surplus power is within a preset range, the switching-in and switching-out state of the switch sub-module 11 is controlled by a grouping step-by-step manner to match the energy consumption power with the system surplus power.

[0105] When the system surplus power exceeds the preset range, the second power switch tube 112 is controlled to be turned on to connect the flood discharge resistor to both ends of the absorption capacitor 114 to match the energy consumption power with the system surplus power.

[0106] In one embodiment, the switching-in and switching-out state of the switch sub-module 11 is controlled by a grouping step-by-step manner, including:

[0107] The switching-in and switching-out state of the switch sub-module is controlled by a grouping step-by-step manner to divide the system surplus power into several parts.

[0108] In one embodiment, the second power switch tube 112 is controlled to be turned on, including:

[0109] According to a voltage balance relationship of the offshore wind power DC energy consumption device, the on-time of the second power switch tube 112 is controlled.

[0110] The voltage balance relationship includes:

[0111] U dc = U sm + U R

[0112] In the formula, U dc is the voltage across the DC transmission line, U sm is the voltage across the energy consumption valve 10, and U R is the voltage across the concentrated energy consumption resistor 20.

[0113] In one embodiment, the second power switch tube 112 is controlled to be turned on, further including:

[0114] According to a system power balance relationship of the offshore wind power DC energy consumption device, the turn-on time of the second power switch tube 112 is controlled;

[0115] The system power balance relationship includes;

[0116] p extra = p R + p r

[0117] In the formula, p extra is a system surplus power, p R is a power consumed by the energy consumption resistor 20, and p r is a dissipation power of the discharge resistor 115.

[0118] One embodiment of the present application provides a computer readable storage medium including a stored computer program, wherein the computer readable storage medium controls the device where the computer readable storage medium is located to perform the control method of the offshore wind power DC energy consumption device based on the sub-module as described above when the computer program runs.

[0119] The above is the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements also regarded as the protection scope of the present application.

Claims

1. A control method of a sub-module-based offshore wind power DC energy dissipation device, suitable for an offshore wind power DC energy dissipation device, characterized in that, The offshore wind power DC energy consumption device comprises: an energy consumption valve and an energy consumption resistor connected in series with the energy consumption valve; the energy consumption valve comprises a plurality of switch sub-modules, and the plurality of switch sub-modules are connected in series; the switch sub-module comprises a first power switch tube, a second power switch tube, an anti-reverse diode, an absorption capacitor and a discharge resistor; the drain electrode of the first power switch tube is connected with the anode of the anti-reverse diode, the source electrode of the first power switch tube is connected with one end of the discharge resistor, the cathode of the anti-reverse diode is connected with the source electrode of the second power switch tube, the drain electrode of the second power switch tube is connected with the other end of the discharge resistor, one end of the absorption capacitor is connected with the cathode of the anti-reverse diode, and the other end of the absorption capacitor is connected with the source electrode of the first power switch tube; the first power switch tube is used for controlling the input and output state of the switch sub-module; the second power switch tube is used for controlling the energy release of the absorption capacitor to the discharge resistor; the anti-reverse diode is used for preventing the energy in the absorption capacitor from being released to the DC bus; the absorption capacitor is used for supporting the voltage of the switch sub-module and absorbing the surplus impact power of the system; the discharge resistor is used for releasing the energy in the absorption capacitor; the control method comprises: during the operation of the offshore wind power DC energy consumption device, the surplus power of the system is obtained; according to the surplus power of the system, the input and output state of the switch sub-module is controlled; according to the surplus power of the system, the input and output state of the switch sub-module is controlled, which comprises: when the surplus power of the system is within a preset range, the input and output state of the switch sub-module is controlled by a grouping step-by-step mode, so that the energy consumption power matches the surplus power of the system; when the surplus power of the system exceeds the preset range, the second power switch tube is controlled to be turned on, and the discharge resistor is connected across the absorption capacitor, so that the energy consumption power matches the surplus power of the system; the control of the second power switch tube to be turned on comprises: according to the voltage balance relationship of the offshore wind power DC energy consumption device, the turn-on time of the second power switch tube is controlled; the voltage balance relationship comprises: U dc = U sm + U R where U dc is the voltage across the DC feed line, U sm is the voltage across the energy-consuming valve, U R is the voltage across the central energy-consuming resistor.

2. The control method of the submodule-based offshore wind power DC energy dissipation device according to claim 1, characterized in that, according to the surplus power of the system, the input and output state of the switch sub-module is controlled, which comprises: when the surplus power of the system is within a preset range, the input and output state of the switch sub-module is controlled by a grouping step-by-step mode, so that the energy consumption power matches the surplus power of the system; when the surplus power of the system exceeds the preset range, the second power switch tube is controlled to be turned on, and the discharge resistor is connected across the absorption capacitor, so that the energy consumption power matches the surplus power of the system. the control of the input and output state of the switch sub-module by the grouping step-by-step mode comprises:

3. The control method of the submodule-based offshore wind power DC energy dissipation device according to claim 2, characterized in that, the surplus power of the system is divided into several parts by controlling the input and output state of the switch sub-module by the grouping step-by-step mode. the control of the second power switch tube to be turned on further comprises:

4. The control method of the submodule-based offshore wind power DC energy dissipation device according to claim 2, characterized in that, according to the system power balance relationship of the offshore wind power DC energy consumption device, the turn-on time of the second power switch tube is controlled; the system power balance relationship comprises: ​ p extra = p R + p r where p extra is the system surplus power, p R is the power dissipated by the energy consuming resistor, p r is the power dissipated by the bleed resistor.

5. A control device of a sub-module-based offshore wind power DC energy dissipation device, characterized in that, The application relates to a DC energy consumption device for offshore wind power, which comprises: an energy consumption valve and an energy consumption resistor connected in series with the energy consumption valve; the energy consumption valve comprises a plurality of switch sub-modules, and the plurality of switch sub-modules are connected in series; the switch sub-module comprises a first power switch tube, a second power switch tube, an anti-reverse diode, an absorption capacitor and a discharge resistor; the drain electrode of the first power switch tube is connected with the anode of the anti-reverse diode, the source electrode of the first power switch tube is connected with one end of the discharge resistor, the cathode of the anti-reverse diode is connected with the source electrode of the second power switch tube, the drain electrode of the second power switch tube is connected with the other end of the discharge resistor, one end of the absorption capacitor is connected with the cathode of the anti-reverse diode, and the other end of the absorption capacitor is connected with the source electrode of the first power switch tube; the first power switch tube is used for controlling the input and output state of the switch sub-module; the second power switch tube is used for controlling the energy release of the absorption capacitor to the discharge resistor; the anti-reverse diode is used for preventing the energy in the absorption capacitor from being released to the busbar; the absorption capacitor is used for supporting the voltage of the switch sub-module and absorbing the surplus impact power of the system; the discharge resistor is used for releasing the energy in the absorption capacitor; the control device comprises: a system surplus power acquisition module used for acquiring the system surplus power during the operation of the DC energy consumption device for offshore wind power; a switch sub-module switching state control module used for controlling the input and output state of the switch sub-module according to the system surplus power; the control of the input and output state of the switch sub-module according to the system surplus power comprises: when the system surplus power is within a preset range, the input and output state of the switch sub-module is controlled in a group ladder mode so as to match the energy consumption power with the system surplus power; and when the system surplus power exceeds the preset range, the second power switch tube is controlled to be turned on, and the discharge resistor is connected across the absorption capacitor so as to match the energy consumption power with the system surplus power; the control of the second power switch tube to be turned on comprises: controlling the turn-on time of the second power switch tube according to the voltage balance relationship of the DC energy consumption device for offshore wind power; the voltage balance relationship comprises: U dc = U sm + U R where U dc is the voltage across the DC feed line, U sm is the voltage across the energy consuming valve, U R is the voltage across the concentrated energy consuming resistor.

6. A computer-readable storage medium, characterized in that, the computer readable storage medium comprises a stored computer program, wherein the computer readable storage medium controls the device where the computer readable storage medium is located to execute the control method of the sub-module-based DC energy consumption device for offshore wind power according to any one of claims 1 to 4 when the computer program is executed.

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