DC energy consumption circuit control method and device and converter valve control method and device

Abstract

The present invention discloses a method and device for controlling a DC energy consumption circuit, wherein the method includes: detecting the DC voltage of the DC energy consumption circuit; judging whether the value of the DC voltage of the DC energy consumption circuit is greater than or equal to a first preset voltage value; when the value of the DC voltage of the DC energy consumption circuit is greater than or equal to the first preset voltage value, the DC energy consumption circuit is put into operation by sequentially cutting off a number of switch modules according to a first preset slope. A method and device for controlling a converter valve is also disclosed. By sequentially switching on or off a plurality of switch modules in a DC energy consumption circuit according to a preset slope, the rate of change of current during switching is reduced, and the fluctuation of DC voltage is reduced; and the modulation voltage of each bridge arm is adjusted according to the first preset slope to offset the voltage drop on the reactance of each bridge arm caused by the current change, and further reduce the fluctuation of DC current, thereby avoiding problems that endanger the safety of equipment such as flexible DC converter valves.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current energy consumption control, and in particular to a direct current energy consumption circuit control method and device and a converter valve control method and device. Background Art

[0002] With the development of fully controlled power electronic devices and the application of power electronic technology in power systems, flexible direct current transmission technology based on voltage source converters has received increasing attention. Flexible direct current transmission converters have advantages such as low voltage harmonic content, high waveform quality, and the ability to quickly adjust active power and reactive power. They have the ability to connect to large power grids or connect to isolated power grids. These technical advantages have led to a wide range of application demands for flexible direct current technology in power systems, such as large-scale access, collection and transmission of clean energy, and power supply for isolated passive loads. When flexible direct current is used for isolated transmission of new energy systems, when a fault occurs at the receiving end and causes the voltage of the AC power grid to drop, the active power cannot be sent or can only be partially sent to the AC power grid. The excess active power causes the voltage of the DC transmission line to increase, endangering the safety of equipment such as flexible direct current converter valves.

[0003] The existing technical solution can discharge the surplus power through the DC energy consumption circuit to improve the fault ride-through capability of the system. The current common DC energy consumption circuit topology is to connect multiple switch modules with energy consumption resistors, and realize the switching on and off of the DC energy consumption circuit by controlling the switching on or off of multiple switch modules. When the DC energy consumption circuit is cut off, the output voltage of the switch module is the rated value, and the current flowing through the energy consumption resistor is 0; when the DC energy consumption circuit is switched on, the output voltage of the switch module is 0, and the current flowing through the energy consumption resistor is the rated value. During AC faults, in order to balance the system power, the DC energy consumption circuit needs to be switched on and off multiple times. Each state switch is accompanied by a rapid change in the current flowing through the DC energy consumption circuit and the converter valve, which leads to a large induced electromotive force at both ends of the inductive element, causing large fluctuations in the DC voltage, affecting the stability of the system. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a method and device for controlling a DC energy consumption circuit, which reduces the rate of change of current during the switching process of the DC energy consumption circuit by sequentially switching multiple switch modules on or off according to a preset slope, and reduces the fluctuation of the DC voltage; and also provides a converter valve control method, which adjusts the modulation voltage of each bridge arm according to the preset slope of controlling the switching of multiple switch modules of the DC energy consumption circuit to offset the voltage drop on the reactance of each bridge arm caused by the current change caused by the switching of the DC energy consumption circuit, and further reduces the fluctuation of the DC current.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a DC energy consumption circuit control method, wherein the DC energy consumption circuit includes an energy consumption resistor component and a plurality of switch modules connected in series, and comprises the following steps:

[0006] Detecting a DC voltage of the DC energy consumption circuit;

[0007] Determine whether the value of the DC voltage of the DC energy consumption circuit is greater than or equal to a first preset voltage value, wherein the first preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from a cut-off state to an input state;

[0008] When the DC voltage of the DC energy consumption circuit is greater than or equal to the first preset voltage value, the DC energy consumption circuit is put into an on state by sequentially cutting off the plurality of switch modules at a first preset time interval.

[0009] Furthermore, the DC energy consumption circuit control method further includes: when the DC voltage of the DC energy consumption circuit is less than the first preset voltage value, controlling the plurality of switch modules to remain in the on state so that the DC energy consumption circuit remains in the off state.

[0010] Furthermore, the DC energy consumption circuit control method further includes:

[0011] Continuing to detect the DC voltage of the DC energy consumption circuit;

[0012] Determine whether the value of the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value, wherein the second preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from an on state to a off state;

[0013] When the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value, the DC energy consumption circuit is adjusted from the switched-on state to the switched-off state by sequentially switching on the plurality of switch modules at a second preset time interval.

[0014] Furthermore, the DC energy consumption circuit control method further includes:

[0015] When the value of the DC voltage of the DC energy consumption circuit is greater than the second preset voltage value, the plurality of switch modules are controlled to remain in a cut-off state, so that the DC energy consumption circuit remains in an on state.

[0016] Furthermore, the second preset time interval has the same value as the first preset time interval.

[0017] A second aspect of the present invention provides a DC energy consumption circuit control device, wherein the DC energy consumption circuit includes an energy consumption resistor component and a plurality of switch modules connected in series, including:

[0018] A first detection module, used for detecting the DC voltage of the DC energy consumption circuit;

[0019] A first judgment module, judging whether the value of the DC voltage of the DC energy consumption circuit is greater than or equal to a first preset voltage value, wherein the first preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from a cut-off state to an input state;

[0020] The first control module is used to adjust the DC energy consumption circuit from a cut-off state to an on state by sequentially cutting off the plurality of switch modules at a first preset time interval when the DC voltage of the DC energy consumption circuit is greater than or equal to the first preset voltage value.

[0021] Furthermore, the first control module is also used to control the plurality of switch modules to remain in an on state so that the DC energy consumption circuit remains in a cut-off state when the DC voltage of the DC energy consumption circuit is less than the first preset voltage value.

[0022] Furthermore, the DC energy consumption circuit control device further comprises:

[0023] A second judgment module is used to judge whether the value of the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value, wherein the second preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from an on state to a off state;

[0024] The second control module is used to adjust the DC energy consumption circuit from the on state to the off state by sequentially switching on the plurality of switch modules at a second preset time interval when the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value.

[0025] Furthermore, the second control module is also used to control the plurality of switch modules to remain in a cut-off state so that the DC energy consumption circuit remains in an on state when the DC voltage of the DC energy consumption circuit is greater than the second preset voltage value.

[0026] Furthermore, the second preset time interval has the same value as the first preset time interval.

[0027] A third aspect of the present invention provides a converter valve control method, wherein the converter valve is connected to a DC energy consumption circuit controlled by the DC energy consumption circuit control method provided by the first aspect of the embodiment of the present invention, comprising the following steps:

[0028] Detecting status information of the DC energy consumption circuit;

[0029] When the DC energy consumption circuit is adjusted from the cut-off state to the put-in state, the voltage instructions of the bridge arms of the control valve are increased by a third preset voltage value;

[0030] When the DC energy consumption circuit is adjusted from the input state to the cut-off state, the voltage instructions of the bridge arms of the control valve are reduced to the third preset voltage value;

[0031] The third preset voltage value is a voltage change value of the converter valve bridge arm reactance caused by a state change of the DC energy consumption circuit, and is negatively correlated with a first preset time interval for cutting off a plurality of switch modules of the DC energy consumption circuit.

[0032] Furthermore, the value of the third preset voltage value is:

[0033]

[0034] Among them, L arm is the arm bridge reactance value of the converter valve, L dc is the inductance of the DC reactor, I dc_chopper is the rated current value of the DC energy consumption circuit, and ΔT is the duration of the DC energy consumption circuit cutting off the plurality of switch modules according to the first preset time interval.

[0035] Furthermore, the duration ΔT of the DC energy consumption circuit cutting off the plurality of switch modules according to the first preset time interval is:

[0036]

[0037] Among them, N sm is the number of switch modules in the DC energy consumption circuit, and k is the number of switch modules switched on or off per unit time.

[0038] A fourth aspect of the present invention provides a converter valve control device, wherein the converter valve is connected to a DC energy consumption circuit controlled by the DC energy consumption circuit control method provided by the first aspect of the embodiment of the present invention, and comprises:

[0039] A second detection module, used to detect the state information of the DC energy consumption circuit;

[0040] A third control module, used for controlling a plurality of bridge arm voltage instructions of the converter valve to increase a third preset voltage value when the DC energy consumption circuit is adjusted from a cut-off state to an input state;

[0041] A fourth control module, used for controlling a plurality of bridge arm voltage instructions of the converter valve to reduce the third preset voltage value when the DC energy consumption circuit is adjusted from the input state to the cut-off state;

[0042] The third preset voltage value is a voltage change value of the bridge arm reactance of the converter valve caused by a state change of the DC energy consumption circuit.

[0043] Furthermore, the value of the third preset voltage value is:

[0044]

[0045] Among them, L arm is the arm bridge reactance value of the converter valve, L dc is the inductance of the DC reactor, I dc_chopper is the rated current value of the DC energy consumption circuit, and ΔT is the duration of the DC energy consumption circuit cutting off the plurality of switch modules according to the first preset time interval.

[0046] Furthermore, the duration ΔT of the DC energy consumption circuit cutting off the plurality of switch modules according to the first preset time interval is:

[0047]

[0048] Among them, N sm is the number of switch modules in the DC energy consumption circuit, and k is the number of switch modules switched on or off per unit time.

[0049] The above technical solution of the embodiment of the present invention has the following beneficial technical effects:

[0050] By sequentially switching on or off multiple switch modules in a DC energy consumption circuit according to a preset slope, the rate of change of current during the switching process of the DC energy consumption circuit is reduced, and the fluctuation of the DC voltage is reduced; by adjusting the modulation voltage of each bridge arm according to the preset slope of controlling the switching on or off of multiple switch modules in the DC energy consumption circuit, the voltage drop on the reactance of each bridge arm caused by the current change caused by the switching of the DC energy consumption circuit is offset, and the fluctuation of the DC current is further reduced, thereby avoiding the problem that the voltage of the DC transmission line increases due to equipment failure, thereby endangering the safety of equipment such as flexible DC converter valves. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic diagram of an offshore wind power DC transmission system provided by an embodiment of the present invention;

[0052] Figure 2 is a schematic diagram of a DC energy consumption circuit provided by an embodiment of the present invention;

[0053] Figure 3 is a flow chart of a DC energy consumption circuit control method provided by an embodiment of the present invention;

[0054] Figure 4 is a module diagram of a DC energy consumption circuit control device provided by an embodiment of the present invention;

[0055] Figure 5 is a schematic diagram of an onshore converter station provided by an embodiment of the present invention;

[0056] Figure 6 is a flow chart of a converter valve control method provided by an embodiment of the present invention;

[0057] Figure 7 is a module diagram of a converter valve control device provided by an embodiment of the present invention;

[0058] Figure 8 It is a schematic diagram of the principle of an offshore wind power DC transmission system that does not adopt the control method of the present invention;

[0059] Fig. 9 It is a schematic diagram of the principle of an offshore wind power DC transmission system provided by an embodiment of the present invention.

[0060] Reference numerals:

[0061] 1. A first detection module, 2. A first judgment module, 3. A first control module, 4. A second judgment module, 5. A second control module, 6. A second detection module, 7. A third control module, 8. A fourth control module. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0063] Figure 1 It is a schematic diagram of an offshore wind power DC transmission system provided by an embodiment of the present invention.

[0064] Please refer to Figure 1 The offshore wind power DC transmission system includes an offshore wind farm, an offshore converter station, a DC energy-consuming circuit and an onshore converter station. The AC side of the onshore converter station is connected to the external AC power grid and is responsible for stabilizing the system DC voltage. The DC side of the onshore converter station is connected to the DC energy-consuming circuit and then connected to the DC side of the offshore AC station through a DC submarine cable. The AC side of the offshore converter station is connected to the offshore wind farm through an AC submarine cable to provide AC system voltage and frequency support for the offshore wind farm. When a transient short-circuit fault occurs in the onshore AC system, the power exchange between the onshore converter station and the AC system is interrupted, and the onshore converter station loses the ability to control the DC voltage, resulting in a rapid rise in the system voltage and an overvoltage shutdown; the DC converter circuit is set on the DC side of the onshore converter station, and can continuously switch on and off energy-consuming resistors during the fault ride-through period to maintain system power balance and avoid DC overvoltage.

[0065] Figure 2 Schematic diagram of a DC energy consumption circuit provided by an embodiment of the present invention.

[0066] Please refer to Figure 2 The DC energy consumption circuit includes an energy consumption resistor component and a plurality of switch modules connected in series, and the energy consumption resistor component includes one or more energy consumption resistors. Optionally, the plurality of energy consumption resistors can be centrally arranged or distributedly arranged, and are respectively arranged between a plurality of switch modules connected in series. The switch module includes at least two states of being put into operation or being cut off, and includes at least a capacitor and one or more switch devices connected in series therewith, and can be a half-bridge submodule or a full-bridge submodule. The switch module in the embodiment of the present invention is only used to illustrate the technical solution of the present invention, but is not limited thereto.

[0067] Figure 3 It is a flow chart of a DC energy consumption circuit control method provided by an embodiment of the present invention.

[0068] Please refer to Figure 3 A first aspect of an embodiment of the present invention provides a method for controlling a DC energy consumption circuit, wherein the DC energy consumption circuit includes an energy consumption resistor component and a plurality of switch modules connected in series, and includes the following steps:

[0069] S110, detecting the DC voltage of the DC energy consumption circuit.

[0070] S210, determining whether the DC voltage of the DC energy consumption circuit is greater than or equal to a first preset voltage value, wherein the first preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from a cut-off state to an on state.

[0071] S310, when the DC voltage of the DC energy consumption circuit is greater than or equal to the first preset voltage value, the DC energy consumption circuit is put into the on state by cutting off a plurality of switch modules in sequence according to the first preset time interval k1, and the state STATE of the DC energy consumption circuit is marked as "1".

[0072] In addition, the DC energy consumption circuit control method further includes:

[0073] S410: When the value of the DC voltage of the DC energy consumption circuit is less than the first preset voltage value, a plurality of switch modules are controlled to remain in the on state, so that the DC energy consumption circuit remains in the off state.

[0074] In one implementation of this embodiment, the DC energy consumption circuit control method further includes:

[0075] S510, continue to detect the DC voltage of the DC energy consumption circuit.

[0076] S610, determining whether the DC voltage of the DC energy consumption circuit is less than or equal to a second preset voltage value, wherein the second preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from an on state to a off state.

[0077] S710, when the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value, a number of switch modules are sequentially switched on at a second preset time interval k2 to adjust the DC energy consumption circuit from the switched on state to the switched off state, and the state STATE of the DC energy consumption circuit is marked as "0".

[0078] In addition, the DC energy consumption circuit control method further includes:

[0079] S810: When the value of the DC voltage of the DC energy consumption circuit is greater than the second preset voltage value, a plurality of switch modules are controlled to remain in the cut-off state, so that the DC energy consumption circuit remains in the on state.

[0080] Optionally, the second preset time interval k2 has the same value as the first preset time interval k1, both being k, that is, the process of sequentially removing a number of switch modules according to the first preset time interval k1 and sequentially adding a number of switch modules according to the second preset time interval k2 is similar.

[0081] Figure 4 It is a module diagram of a DC energy consumption circuit control device provided in an embodiment of the present invention.

[0082] Please refer to Figure 5 According to a second aspect of an embodiment of the present invention, there is provided a control device for a DC energy consumption circuit, wherein the DC energy consumption circuit comprises an energy consumption resistor component and a plurality of switch modules connected in series, and comprises: a first detection module 1, a first judgment module 2 and a first control module 3. The first detection module 1 is used to detect the DC voltage of the DC energy consumption circuit. The first judgment module 2 judges whether the value of the DC voltage of the DC energy consumption circuit is greater than or equal to a first preset voltage value, wherein the first preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from a cut-off state to an engaged state. The first control module 3 is used to adjust the DC energy consumption circuit from a cut-off state to an engaged state by sequentially cutting off a plurality of switch modules at a first preset time interval when the value of the DC voltage of the DC energy consumption circuit is greater than or equal to the first preset voltage value.

[0083] Optionally, the first control module 3 is further used to control a plurality of switch modules to remain in an on state so that the DC energy consumption circuit remains in a cut-off state when the DC voltage of the DC energy consumption circuit is less than a first preset voltage value.

[0084] The DC energy consumption circuit control device further includes: a second judgment module 4 and a second control module 5. The second judgment module 4 is used to judge whether the value of the DC voltage of the DC energy consumption circuit is less than or equal to a second preset voltage value, wherein the second preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from the on state to the off state. The second control module 5 is used to adjust the DC energy consumption circuit from the on state to the off state by sequentially switching on a plurality of switch modules at a second preset time interval when the value of the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value.

[0085] The second control module 5 is also used for controlling a plurality of switch modules to maintain a cut-off state when the value of the DC voltage of the DC energy consumption circuit is greater than a second preset voltage value, so that the DC energy consumption circuit remains in an on state.

[0086] The second preset time interval has the same value as the first preset time interval.

[0087] Figure 5 It is a schematic diagram of an onshore converter station provided by an embodiment of the present invention.

[0088] Please refer to Figure 5 ,The onshore converter station usually uses the current inner loop as the inner loop controller. The current inner loop collects the AC current as the control object, which is finally converted into the bridge arm voltage command after passing the PI controller and is distributed to each bridge arm.

[0089] Figure 6 It is a flow chart of a converter valve control method provided in an embodiment of the present invention.

[0090] Please refer to Figure 6 A third aspect of an embodiment of the present invention provides a converter valve control method, wherein the converter valve is connected to a DC energy consumption circuit controlled by the DC energy consumption circuit control method, and comprises the following steps:

[0091] S120, detecting status information of a DC energy consumption circuit.

[0092] S220, when the DC energy consumption circuit is adjusted from the cut-off state to the put-in state, the voltage instructions of several bridge arms of the control converter valve are increased by a third preset voltage value.

[0093] S320, when the DC energy consumption circuit is adjusted from the on state to the off state, the voltage instructions of several bridge arms of the control converter valve are reduced by a third preset voltage value.

[0094] The third preset voltage value is a voltage change value of the converter valve bridge arm reactance caused by a state change of the DC energy consumption circuit, and is negatively correlated with a first preset time interval for cutting off a plurality of switch modules of the DC energy consumption circuit.

[0095] Furthermore, the value of the third preset voltage value is:

[0096]

[0097] Among them, L arm is the arm bridge reactance value of the converter valve, L dc is the inductance of the DC reactor, I dc_chopper is the rated current value of the DC energy consumption circuit, and ΔT is the duration of the DC energy consumption circuit cutting off a plurality of switch modules according to the first preset time interval.

[0098] The duration ΔT of the DC energy consumption circuit cutting off a plurality of switch modules according to the first preset time interval is:

[0099]

[0100] Among them, N sm is the number of switch modules in the DC energy consumption circuit, k is the number of switch modules switched on or off per unit time, and in this embodiment, the first preset time interval k1 and the second preset time interval k2 in the DC energy consumption circuit control method are the same, both being k.

[0101] Figure 7 It is a module diagram of a converter valve control device provided in an embodiment of the present invention.

[0102] Please refer to Figure 7 In a fourth aspect, an embodiment of the present invention provides a converter valve control device, wherein the converter valve is connected to a DC energy consumption circuit controlled by the DC energy consumption circuit control method, and comprises: a second detection module 6, a third control module 7 and a fourth control module 8. The second detection module 6 is used to detect the state information of the DC energy consumption circuit. The third control module 7 is used to control a plurality of bridge arm voltage instructions of the converter valve to increase a third preset voltage value when the DC energy consumption circuit is adjusted from a cut-off state to an input state. The fourth control module 8 is used to control a plurality of bridge arm voltage instructions of the converter valve to reduce a third preset voltage value when the DC energy consumption circuit is adjusted from an input state to a cut-off state.

[0103] The third preset voltage value is a voltage change value of the converter valve bridge arm reactance caused by a state change of the DC energy consumption circuit, and is negatively correlated with a first preset time interval for cutting off a plurality of switch modules of the DC energy consumption circuit.

[0104] Furthermore, the value of the third preset voltage value is:

[0105]

[0106] Among them, L arm is the arm bridge reactance value of the converter valve, L dc is the inductance of the DC reactor, I dc_chopperis the rated current value of the DC energy consumption circuit, and ΔT is the duration of the DC energy consumption circuit cutting off a plurality of switch modules according to the first preset time interval.

[0107] The duration ΔT of the DC energy consumption circuit cutting off a plurality of switch modules according to the first preset time interval is:

[0108]

[0109] Among them, N sm is the number of switch modules in the DC energy consumption circuit, and k is the number of switch modules switched on or off per unit time.

[0110] Figure 8 It is a schematic diagram of the principle of an offshore wind power DC transmission system that does not adopt the control method of the present invention.

[0111] Fig. 9 It is a schematic diagram of the principle of an offshore wind power DC transmission system provided by an embodiment of the present invention.

[0112] Please refer to Figure 1 A fifth aspect of an embodiment of the present invention provides an offshore wind power DC transmission system, comprising: an offshore wind farm, an offshore converter station, a DC energy consumption circuit and an onshore converter station connected in sequence, the onshore converter station is also connected to an external power grid; the DC energy consumption circuit uses the aforementioned DC energy consumption circuit control method; and / or the onshore converter station includes a converter valve controlled by the aforementioned converter valve control method.

[0113] like Figure 8 As shown in Figure 1, at the beginning, when a transient short circuit fault occurs in the onshore AC power grid, the offshore wind farm continues to inject active power into the system, causing the DC voltage to rise.

[0114] At t1, the DC voltage rises to the set value E up , the state STATE of the DC energy consumption device changes to "1", all submodules in the device are cut off, the current in the energy consumption device increases rapidly from 0 to the rated value, the current in the bridge arm of the onshore converter station decreases rapidly, and a high induced electromotive force appears at both ends of the inductive element in the bridge arm, resulting in an increase in DC voltage fluctuations. At t2, the DC voltage drops to the set value E down , the state STATE of the DC energy consumption device becomes "0", all submodules in the device are put into operation, the current in the energy consumption device rapidly decreases from the rated value to 0, the current in the bridge arm of the onshore converter station rapidly decreases, and a high induced electromotive force appears at both ends of the inductive elements in the bridge arm, resulting in an increase in the DC voltage fluctuation.

[0115] like Fig. 9 As shown in Figure 1, at the beginning, when a transient short circuit fault occurs in the onshore AC power grid, the offshore wind farm continues to inject active power into the system, causing the DC voltage to rise.

[0116] At t1, the DC voltage rises to the set value E up , the state STATE of the DC energy consumption device changes to "1", and the submodules in the DC energy consumption device are removed one by one along the ramp with a slope of k until the number of submodules put into operation drops to 0. At the same time, the converter valve controller receives the state STATE of the DC energy consumption device, and detects that STATE changes from "0" to "1" at time t1, and adds a voltage increment ΔU to the bridge arm voltage command for a duration of ΔT. ΔT is equal to the time for the energy consumption device to be put into operation or removed according to the ramp, which can be calculated according to the following formula:

[0117]

[0118] The regulated voltage ΔU is equal to the voltage drop on the bridge arm reactance caused by the current change caused by the switching of the energy-consuming device, which can be calculated according to the following formula:

[0119]

[0120] At time t2, all submodules in the energy-consuming device are cut off, the energy consumption of the energy-consuming resistor reaches the maximum value, and the system DC voltage gradually decreases.

[0121] At t3, the DC voltage drops to the set value E down , the state STATE of the DC energy consumption device changes to "0", and the submodules in the DC energy consumption device are put into operation one by one along the ramp with a slope of k until the number of submodules put into operation reaches the rated value N sm At the same time, the converter valve controller receives the state STATE of the DC energy consumption device, detects that STATE changes from "1" to "0" at time t3, and adds a voltage increment -ΔU to the bridge arm voltage instruction for a duration of ΔT. The calculation methods of ΔU and ΔT are as described above.

[0122] At t4, all submodules in the energy-consuming device are put into operation, the voltage across the energy-consuming resistor is 0, and no energy is consumed. The system DC voltage rises again due to power imbalance. During the transient fault period, the DC voltage will be roughly controlled at the set value E up and E down The DC voltage fluctuation is effectively suppressed.

[0123] Depend on Figure 7 and Figure 8 It can be seen that the control method of the present invention can effectively suppress the DC voltage fluctuation during the fault ride-through process of the offshore wind power DC transmission system, while also not affecting the function of the energy-consuming device in absorbing redundant energy during the fault ride-through period.

[0124] A sixth aspect of an embodiment of the present invention provides an electronic device, comprising: at least one processor; and a memory connected to the at least one processor; wherein the memory stores instructions that can be executed by a processor, and the instructions are executed by a processor so that the at least one processor executes the aforementioned DC energy consumption circuit control method and / or executes the aforementioned converter valve control method.

[0125] A seventh aspect of an embodiment of the present invention provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the aforementioned DC energy consumption circuit control method and / or the aforementioned converter valve control method.

[0126] The embodiments of the present invention are intended to protect a DC energy consumption circuit control method and device and a converter valve control method and device, and have the following effects:

[0127] By sequentially switching on or off multiple switch modules in a DC energy consumption circuit according to a preset slope, the rate of change of current during the switching process of the DC energy consumption circuit is reduced, and the fluctuation of the DC voltage is reduced; by adjusting the modulation voltage of each bridge arm according to the preset slope of controlling the switching on or off of multiple switch modules in the DC energy consumption circuit, the voltage drop on the reactance of each bridge arm caused by the current change caused by the switching of the DC energy consumption circuit is offset, and the fluctuation of the DC current is further reduced, thereby avoiding the problem that the voltage of the DC transmission line increases due to equipment failure, thereby endangering the safety of equipment such as flexible DC converter valves.

[0128] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A method for controlling a DC energy consumption circuit, wherein the DC energy consumption circuit comprises an energy consumption resistor component and a plurality of switch modules connected in series, characterized in that: The steps include: Detecting a DC voltage of the DC energy consumption circuit; Determine whether the value of the DC voltage of the DC energy consumption circuit is greater than or equal to a first preset voltage value, wherein the first preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from a cut-off state to an input state; When the DC voltage of the DC energy consumption circuit is greater than or equal to the first preset voltage value, the DC energy consumption circuit is put into an on state by sequentially cutting off the plurality of switch modules at a first preset time interval; Also includes: When the DC voltage of the DC energy consumption circuit is less than the first preset voltage value, the plurality of switch modules are controlled to remain in the on state, so that the DC energy consumption circuit remains in the off state; Also includes: Continuing to detect the DC voltage of the DC energy consumption circuit; Determine whether the DC voltage of the DC energy consumption circuit is less than or equal to a second preset voltage value, wherein the second preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from an on state to a off state; When the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value, the DC energy consumption circuit is adjusted from the switched-on state to the switched-off state by sequentially switching on the plurality of switch modules at a second preset time interval; Also includes: When the value of the DC voltage of the DC energy consumption circuit is greater than the second preset voltage value, the plurality of switch modules are controlled to remain in a cut-off state, so that the DC energy consumption circuit remains in an on state.

2. The DC energy consumption circuit control method according to claim 1, characterized in that: The second preset time interval has the same value as the first preset time interval.

3. A DC energy consumption circuit control device, wherein the DC energy consumption circuit comprises an energy consumption resistor component and a plurality of switch modules connected in series, characterized in that: include: A first detection module, used for detecting the DC voltage of the DC energy consumption circuit; A first judgment module, judging whether the value of the DC voltage of the DC energy consumption circuit is greater than or equal to a first preset voltage value, wherein the first preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from a cut-off state to an input state; a first control module, configured to adjust the DC energy consumption circuit from a cut-off state to an on state by sequentially cutting off the plurality of switch modules at a first preset time interval when the DC voltage of the DC energy consumption circuit is greater than or equal to the first preset voltage value; The first control module is further used to control the plurality of switch modules to remain in an on state so that the DC energy consumption circuit remains in a cut-off state when the DC voltage of the DC energy consumption circuit is less than the first preset voltage value; Also includes: A second judgment module is used to judge whether the value of the DC voltage of the DC energy consumption circuit is less than or equal to a second preset voltage value, wherein the second preset voltage value is a voltage threshold for adjusting the DC energy consumption circuit from an on state to a off state; a second control module, configured to, when the DC voltage of the DC energy consumption circuit is less than or equal to the second preset voltage value, sequentially activate the plurality of switch modules at a second preset time interval to adjust the DC energy consumption circuit from an activated state to a removed state; The second control module is further used for controlling the plurality of switch modules to maintain a cut-off state so that the DC energy consumption circuit remains in an on state when the DC voltage of the DC energy consumption circuit is greater than the second preset voltage value.

4. The DC energy consumption circuit control device according to claim 3, characterized in that: The second preset time interval has the same value as the first preset time interval.

5. A converter valve control method, wherein the converter valve is connected to a DC energy consumption circuit controlled by the DC energy consumption circuit control method according to claim 1 or 2, characterized in that: The steps include: Detecting status information of the DC energy consumption circuit; When the DC energy consumption circuit is adjusted from the cut-off state to the put-in state, the voltage instructions of the bridge arms of the control valve are increased by a third preset voltage value; When the DC energy consumption circuit is adjusted from the input state to the cut-off state, the voltage instructions of the bridge arms of the control valve are reduced to the third preset voltage value; The third preset voltage value is a voltage change value of the converter valve bridge arm reactance caused by a state change of the DC energy consumption circuit, and is negatively correlated with a first preset time interval for cutting off a plurality of switch modules of the DC energy consumption circuit.

6. The converter valve control method according to claim 5, characterized in that: The value of the third preset voltage value is: ， in, is the arm bridge reactance value of the converter valve, is the inductance of the DC reactor, is the rated current value of the DC energy consumption circuit, The duration for which the DC energy consumption circuit switches off the plurality of switch modules according to the first preset time interval.

7. The converter valve control method according to claim 6, characterized in that: The duration of the DC energy consumption circuit cutting off the plurality of switch modules according to the first preset time interval for: ， in, is the number of switch modules of the DC energy consumption circuit, It is the number of switch modules switched on or off per unit time.

8. A converter valve control device, wherein the converter valve is connected to a DC energy consumption circuit controlled by the DC energy consumption circuit control method according to claim 1 or 2, characterized in that: include: A second detection module, used to detect the state information of the DC energy consumption circuit; A third control module, used for controlling a plurality of bridge arm voltage instructions of the converter valve to increase a third preset voltage value when the DC energy consumption circuit is adjusted from a cut-off state to an input state; A fourth control module, used for controlling a plurality of bridge arm voltage instructions of the converter valve to reduce the third preset voltage value when the DC energy consumption circuit is adjusted from the input state to the cut-off state; The third preset voltage value is a voltage change value of the converter valve bridge arm reactance caused by a state change of the DC energy consumption circuit, and is negatively correlated with a first preset time interval for cutting off a plurality of switch modules of the DC energy consumption circuit.

9. The converter valve control device according to claim 8, characterized in that: The value of the third preset voltage value is: ， in, is the arm bridge reactance value of the converter valve, is the inductance of the DC reactor, is the rated current value of the DC energy consumption circuit, The duration for which the DC energy consumption circuit switches off the plurality of switch modules according to the first preset time interval.

10. The converter valve control device according to claim 9, characterized in that: The duration of the DC energy consumption circuit cutting off the plurality of switch modules according to the first preset slope for: ， in, is the number of switch modules of the DC energy consumption circuit, It is the number of switch modules switched on or off per unit time.

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