Fault control method suitable for extra-high voltage flexible direct current power transmission system, extra-high voltage flexible direct current power transmission system, medium and equipment

Abstract

The invention discloses a fault control method suitable for an extra-high voltage flexible direct current power transmission system, an extra-high voltage flexible direct current power transmission system, a medium and equipment, and the method comprises the steps: controlling a receiving end energy consumption device to start and maintain operation when detecting that the electrical parameter information of the alternating current side of a receiving end converter station meets a first fault condition; when it is detected that the electrical parameter information meets a second fault condition, the receiving end energy consumption device is controlled to start and maintain operation, and a corresponding control instruction is sent to the sending end converter station according to the mode of the alternating current side of the sending end converter station, so that the sending end converter station enters a corresponding fault processing mode; wherein the fault severity degree indicated by the second fault condition is higher than the fault severity degree indicated by the first fault condition, so that the safety and economical efficiency of the extra-high voltage flexible direct current power transmission system can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of flexible direct current transmission, and in particular to a fault control method applicable to an ultra-high voltage flexible direct current transmission system, an ultra-high voltage flexible direct current transmission system, a medium and equipment. Background Art

[0002] At present, since the distance between the two ends of the UHV flexible DC transmission technology is generally more than 2000km, for the ultra-long transmission distance UHV flexible DC system, when the AC system on the receiving side has a transient fault, the power delivery capacity of the receiving end converter station is limited. However, due to the long communication delay between stations, the power delivered by the sending end converter station for a period of time (more than 30ms) after the fault remains basically unchanged. In this way, during this period of time, there will be significant surplus power in the receiving end converter station. The surplus power will cause the operating voltage of the submodules of the receiving end converter station to continue to increase until the protection lock is triggered or even the flexible DC system is shut down, which will seriously affect the system safety and cause economic losses. Summary of the invention

[0003] In order to solve the above technical problems, the embodiments of the present application propose a fault control method, a UHV flexible DC transmission system, a medium and equipment suitable for a UHV flexible DC transmission system, which can improve the safety and economy of the UHV flexible DC transmission system.

[0004] The embodiment of the present application provides a fault control method applicable to an ultra-high voltage flexible direct current transmission system, wherein the ultra-high voltage flexible direct current transmission system comprises a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, wherein the receiving-end energy consumption device is adapted to consume at least part of the direct current during operation, wherein the at least part of the direct current refers to at least part of the direct current transmitted to the receiving-end converter station, and the method is executed by the receiving-end converter station and comprises:

[0005] When it is detected that the electrical parameter information on the AC side of the receiving-end converter station meets the first fault condition, controlling the receiving-end energy consumption device to start and maintain operation;

[0006] When it is detected that the electrical parameter information meets the second fault condition, the receiving-end energy consumption device is controlled to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, a corresponding control instruction is sent to the sending-end converter station, so that the sending-end converter station enters a corresponding fault processing mode;

[0007] The fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition.

[0008] Optionally, the electrical parameter information includes the three-phase voltage on the AC side of the receiving-end converter station;

[0009] The first fault condition includes that the positive sequence component of the three-phase voltage is in a first set interval;

[0010] The second fault condition includes that the positive sequence component of the three-phase voltage is in a second set interval;

[0011] The lower boundary of the first setting interval and the upper boundary of the second setting interval are equal, both of which are setting voltage thresholds, the first setting interval includes the setting voltage threshold and the second setting interval does not include the setting voltage threshold.

[0012] Optionally, the mode of the communication side includes a networking mode;

[0013] When the mode of the AC side is the networking mode, the fault handling mode is suitable for instructing the DC power transmission power of the DC power transmitted by the sending-end converter station to the receiving-end converter station to be reduced to a target DC output power value.

[0014] Optionally, the target DC output power value P pu Determined by the following formula:

[0015] P pu =U ac,pu +0.5

[0016] Among them, U ac,pu It is the per-unit value of the positive sequence component of the three-phase voltage.

[0017] Optionally, the mode of the AC side includes an island mode, and the sending-end converter station is pre-connected with at least one sending-end energy-consuming device that is turned off by default;

[0018] When the mode on the AC side is the island mode, the fault handling mode is suitable for instructing the sending-end converter station to control at least part of the at least one sending-end energy-consuming device to start and maintain operation, so that the sending-end energy-consuming device that is turned on and running continues to consume the AC power from the sending-end converter station.

[0019] Optionally, the total capacity of the sending-end energy-consuming device that is turned on and running is calculated based on the per-unit value of the drop of the positive-sequence component of the three-phase voltage.

[0020] Optionally, the method further comprises:

[0021] After the first fault condition is met, when it is detected that the electrical parameter information meets the first fault relief condition, controlling the receiving-end energy consumption device to shut down;

[0022] After the second fault condition is met, when it is detected that the electrical parameter information meets the second fault removal condition, the receiving-end energy consumption device is controlled to be turned off, and a fault removal instruction is sent to the sending-end converter station, wherein the fault removal instruction is suitable for instructing the sending-end converter station to exit the fault handling mode.

[0023] In a second aspect, an embodiment of the present application provides an ultra-high voltage flexible direct current power transmission system, the ultra-high voltage flexible direct current power transmission system having a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, the receiving-end energy consumption device being adapted to consume at least part of the direct current during operation, the at least part of the direct current refers to at least part of the direct current transmitted to the receiving-end converter station, and the receiving-end converter station is configured as follows:

[0024] When it is detected that the electrical parameter information on the AC side of the receiving-end converter station meets the first fault condition, controlling the receiving-end energy consumption device to start and maintain operation;

[0025] When it is detected that the electrical parameter information meets the second fault condition, the receiving-end energy consumption device is controlled to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, a corresponding control instruction is sent to the sending-end converter station, so that the sending-end converter station enters a corresponding fault processing mode;

[0026] The fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition.

[0027] Optionally, the receiving-end converter station comprises:

[0028] a first valve group, a first end of which is electrically connected to the positive pole line of the receiving-end converter station, and a second end of which is electrically connected to the AC system;

[0029] a second valve group, wherein a first end is electrically connected to a third end of the first valve group, a second end is electrically connected to the AC system, and a third end is electrically connected to a neutral line of the receiving-end converter station;

[0030] A third valve group, a first end of which is electrically connected to the neutral line of the receiving-end converter station, and a second end of which is electrically connected to the AC system; and

[0031] a fourth valve group, a first end of which is electrically connected to the third end of the third valve group, a second end of which is electrically connected to the AC system, and a third end of which is electrically connected to the negative pole line of the receiving-end converter station;

[0032] Wherein, the two ends of the sending-end converter station are electrically connected to the positive pole line and the negative pole line of the receiving-end converter station respectively.

[0033] Optionally, the receiving-end energy consumption device comprises:

[0034] A first DC energy consumption module, two ends of which are electrically connected to the positive pole line and the neutral line of the receiving-end converter station respectively; and

[0035] The second DC energy consumption module has two ends electrically connected to the neutral line and the negative pole line of the receiving-end converter station respectively.

[0036] Optionally, at least one of the first valve group, the second valve group, the third valve group, and the fourth valve group adopts a full half-bridge hybrid module structure.

[0037] Optionally, the electrical parameter information includes the three-phase voltage on the AC side of the receiving-end converter station;

[0038] The first fault condition includes that the positive sequence component of the three-phase voltage is in a first set interval;

[0039] The second fault condition includes that the positive sequence component of the three-phase voltage is in a second set interval;

[0040] The lower boundary of the first setting interval and the upper boundary of the second setting interval are equal, both of which are setting voltage thresholds, the first setting interval includes the setting voltage threshold and the second setting interval does not include the setting voltage threshold.

[0041] Optionally, the mode of the communication side includes a networking mode;

[0042] When the mode of the AC side is the networking mode, the fault handling mode is suitable for instructing the DC power transmission power of the DC power transmitted by the sending-end converter station to the receiving-end converter station to be reduced to a target DC output power value.

[0043] Optionally, the target DC output power value P pu Determined by the following formula:

[0044] P pu =U ac,pu +0.5

[0045] Among them, U ac,pu It is the per-unit value of the positive sequence component of the three-phase voltage.

[0046] Optionally, the mode of the AC side includes an island mode, and the sending-end converter station is pre-connected with at least one sending-end energy-consuming device that is turned off by default;

[0047] When the mode on the AC side is the island mode, the fault handling mode is suitable for instructing the sending-end converter station to control at least part of the at least one sending-end energy-consuming device to start and maintain operation, so that the sending-end energy-consuming device that is turned on and running continues to consume the AC power from the sending-end converter station.

[0048] Optionally, the total capacity of the sending-end energy-consuming device that is turned on and running is calculated based on the per-unit value of the drop of the positive-sequence component of the three-phase voltage.

[0049] Optionally, the receiving-end converter station is further configured as:

[0050] After the first fault condition is met, when it is detected that the electrical parameter information meets the first fault relief condition, controlling the receiving-end energy consumption device to shut down;

[0051] After the second fault condition is met, when it is detected that the electrical parameter information meets the second fault removal condition, the receiving-end energy consumption device is controlled to be turned off, and a fault removal instruction is sent to the sending-end converter station, wherein the fault removal instruction is suitable for instructing the sending-end converter station to exit the fault handling mode.

[0052] In a third aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of any of the methods described above are implemented.

[0053] In a fourth aspect, an embodiment of the present application provides a computer device, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the steps of any of the methods described above when executing the computer program.

[0054] In summary, the embodiments of the present application have at least the following beneficial effects:

[0055] According to the embodiment of the present application, the ultra-high voltage flexible direct current transmission system has a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, the sending-end converter station is configured to transmit direct current to the receiving-end converter station, the receiving-end energy consumption device is closed by default and pre-connected to the receiving-end converter station, the receiving-end energy consumption device is suitable for consuming at least part of the direct current during operation, the at least part of the direct current refers to at least part of the direct current transmitted to the receiving-end converter station, the method is executed by the receiving-end converter station and includes: when it is detected that the electrical parameter information on the AC side of the receiving-end converter station meets the first When a fault condition occurs, the receiving-end energy-consuming device is controlled to start and maintain operation; when it is detected that the electrical parameter information meets the second fault condition, the receiving-end energy-consuming device is controlled to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, a corresponding control instruction is sent to the sending-end converter station, so that the sending-end converter station enters the corresponding fault handling mode; wherein the fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition, thereby improving the safety and economy of the ultra-high voltage flexible direct current transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a flow chart of a fault control method applicable to a UHV flexible DC power transmission system provided in an embodiment of the present application;

[0057] Figure 2A It is a structural schematic diagram of the ultra-high voltage flexible direct current transmission system provided in an embodiment of the present application;

[0058] Figure 2B It is a structural schematic diagram of the ultra-high voltage flexible direct current transmission system provided in an embodiment of the present application;

[0059] Figure 3 is a schematic diagram of electrical parameter information on a DC pole line during a fault in a networking mode provided by an embodiment of the present application;

[0060] Figure 4 It is a schematic diagram of the maximum voltage of the receiving-end converter valve submodule when a fault occurs in the networking mode provided by an embodiment of the present application;

[0061] Figure 5 is a schematic diagram of electrical parameter information on a DC pole line during a fault in an island mode provided by an embodiment of the present application;

[0062] Figure 6 It is a schematic diagram of the maximum voltage of the receiving-end converter valve submodule when a fault occurs in the island mode provided by an embodiment of the present application;

[0063] Figure 7 It is a schematic diagram of the structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0065] In the description of the present application, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second", "third", etc. may 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. In the description of the present application, the term "including" and its variations are open inclusions, i.e., "including but not limited to". The term "based on" means "at least partially based on". The term "according to" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments".

[0066] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0067] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0068] See also Figure 1 , a flow chart of a fault control method applicable to a UHV flexible DC power transmission system provided by an embodiment of the present application is shown, the UHV flexible DC power transmission system comprises a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, the sending-end converter station is configured to transmit DC power to the receiving-end converter station, the receiving-end energy consumption device is closed by default and pre-connected to the receiving-end converter station, the receiving-end energy consumption device is suitable for consuming at least part of the DC power during operation, the at least part of the DC power refers to at least part of the DC power transmitted to the receiving-end converter station, the method is executed by the receiving-end converter station, the method comprises steps S101-S102, specifically as follows:

[0069] S101, when it is detected that the electrical parameter information of the AC side of the receiving-end converter station meets the first fault condition, controlling the receiving-end energy consumption device to start and maintain operation;

[0070] S102, when it is detected that the electrical parameter information meets the second fault condition, controlling the receiving-end energy consumption device to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, sending a corresponding control instruction to the sending-end converter station, so that the sending-end converter station enters a corresponding fault handling mode;

[0071] The fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition.

[0072] In some embodiments, the UHV flexible DC transmission system can be a typical ±800kV / 8GW UHV flexible DC transmission system, and its main circuit parameters are as follows: submodule rated operating voltage 2.0kV, submodule capacitance 24mF, bridge arm reactor 25mH, current limiting reactor 300mH. The DC transmission line length is 2400km, using 6 split conductors, and the line resistance is about 10Ω. The UHV flexible DC transmission system adopts a true bipolar wiring scheme, with two valve groups cascaded per pole, and the DC voltage of each valve group is 400kV. The valve group adopts a full half-bridge hybrid module, and the full bridge ratio is 60%. The communication delay between stations in the flexible DC system is 30ms.

[0073] In an optional implementation manner, the electrical parameter information includes the three-phase voltage on the AC side of the receiving-end converter station;

[0074] The first fault condition includes that the positive sequence component of the three-phase voltage is in a first set interval;

[0075] The second fault condition includes that the positive sequence component of the three-phase voltage is in a second set interval;

[0076] The lower boundary of the first setting interval and the upper boundary of the second setting interval are equal, both of which are setting voltage thresholds, the first setting interval includes the setting voltage threshold and the second setting interval does not include the setting voltage threshold.

[0077] In some cases, the set voltage threshold in this embodiment may be 0.5 pu, so that when the positive sequence component of the three-phase voltage drops to 0.5 pu, the first fault condition is met.

[0078] In an optional implementation, the mode of the AC side includes a networking mode;

[0079] When the mode of the AC side is the networking mode, the fault handling mode is suitable for instructing the DC power transmission power of the DC power transmitted by the sending-end converter station to the receiving-end converter station to be reduced to a target DC output power value.

[0080] In an optional implementation manner, the target DC output power value P pu Determined by the following formula:

[0081] P pu =U ac,pu +0.5

[0082] Among them, U ac,pu It is the per-unit value of the positive sequence component of the three-phase voltage.

[0083] In an optional implementation, the mode of the AC side includes an island mode, and the sending-end converter station is pre-connected to at least one sending-end energy consumption device that is turned off by default;

[0084] When the mode on the AC side is the island mode, the fault handling mode is suitable for instructing the sending-end converter station to control at least part of the at least one sending-end energy-consuming device to start and maintain operation, so that the sending-end energy-consuming device that is turned on and running continues to consume the AC power from the sending-end converter station.

[0085] In some embodiments, the at least one sending-end energy consumption device may be an AC energy consumption device configured in groups, with each group of 500MW, 8 groups in total, and a total of 4GW. The sending-end energy consumption device may adopt various technical routes such as thyristor control.

[0086] In an optional implementation, the total capacity of the sending-end energy-consuming device that is turned on and running is calculated based on the per-unit value of the drop of the positive-sequence component of the three-phase voltage.

[0087] In some specific examples, the total capacity of the sending-end energy consuming devices that are turned on and running in this embodiment can be determined by the number of the sending-end energy consuming devices that are turned on and running. Assuming that the capacity of each sending-end energy consuming device is equal, the number N of the sending-end energy consuming devices that are turned on and running can be determined by the following formula:

[0088]

[0089] Among them, U ac,pu It is the per-unit value dropped by the positive sequence component of the three-phase voltage, and ROUNDUP[] means rounding up.

[0090] In an optional embodiment, the method further includes:

[0091] After the first fault condition is met, when it is detected that the electrical parameter information meets the first fault relief condition, controlling the receiving-end energy consumption device to shut down;

[0092] After the second fault condition is met, when it is detected that the electrical parameter information meets the second fault removal condition, the receiving-end energy consumption device is controlled to be turned off, and a fault removal instruction is sent to the sending-end converter station, wherein the fault removal instruction is suitable for instructing the sending-end converter station to exit the fault handling mode.

[0093] Second, see Figure 2A and Figure 2B The embodiment of the present application provides a UHV flexible DC power transmission system, the UHV flexible DC power transmission system having a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, the receiving-end energy consumption device is suitable for consuming at least part of the DC power during operation, the at least part of the DC power refers to at least part of the DC power transmitted to the receiving-end converter station, and the receiving-end converter station is configured as follows:

[0094] When it is detected that the electrical parameter information on the AC side of the receiving-end converter station meets the first fault condition, controlling the receiving-end energy consumption device to start and maintain operation;

[0095] When it is detected that the electrical parameter information meets the second fault condition, the receiving-end energy consumption device is controlled to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, a corresponding control instruction is sent to the sending-end converter station, so that the sending-end converter station enters a corresponding fault processing mode;

[0096] The fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition.

[0097] In an optional implementation manner, the receiving-end converter station includes:

[0098] A first valve group 121, a first end of which is electrically connected to the positive pole line of the receiving-end converter station, and a second end of which is electrically connected to the AC system 131;

[0099] A second valve group 122, a first end of which is electrically connected to the third end of the first valve group 121, a second end of which is electrically connected to the AC system 131, and a third end of which is electrically connected to the neutral line of the receiving-end converter station;

[0100] A third valve group 123, a first end of which is electrically connected to the neutral line of the receiving-end converter station, and a second end of which is electrically connected to the AC system 131; and

[0101] A fourth valve group 124, a first end of which is electrically connected to the third end of the third valve group 123, a second end of which is electrically connected to the AC system 131, and a third end of which is electrically connected to the negative pole line of the receiving-end converter station;

[0102] Wherein, the two ends of the sending-end converter station are electrically connected to the positive pole line and the negative pole line of the receiving-end converter station respectively.

[0103] In an optional implementation manner, the receiving-end energy consumption device includes:

[0104] A first DC energy consumption module 111, two ends of which are electrically connected to the positive pole line and the neutral line of the receiving-end converter station respectively; and

[0105] The second DC energy consumption module 112 has two ends electrically connected to the neutral line and the negative pole line of the receiving-end converter station respectively.

[0106] In some embodiments, a 4GW DC energy consumption device may be configured on the DC side of the receiving end converter station, wherein:

[0107] The first DC energy consumption module has a capacity of 2GW and is configured between the positive pole line and the neutral line;

[0108] The second DC energy consumption module has a capacity of 2GW and is configured between the negative pole line and the neutral line;

[0109] In this way, the capacity of the DC energy dissipation device can be only 50% of the rated capacity of the DC power transmission system. The DC energy dissipation device can be constructed using a variety of technical routes such as centralized, distributed or hybrid.

[0110] In an optional embodiment, at least one of the first valve group, the second valve group, the third valve group, and the fourth valve group adopts a full half-bridge hybrid module structure.

[0111] In an optional implementation manner, the electrical parameter information includes the three-phase voltage on the AC side of the receiving-end converter station;

[0112] The first fault condition includes that the positive sequence component of the three-phase voltage is in a first set interval;

[0113] The second fault condition includes that the positive sequence component of the three-phase voltage is in a second set interval;

[0114] The lower boundary of the first setting interval and the upper boundary of the second setting interval are equal, both of which are setting voltage thresholds, the first setting interval includes the setting voltage threshold and the second setting interval does not include the setting voltage threshold.

[0115] In an optional implementation, the mode of the AC side includes a networking mode;

[0116] When the mode of the AC side is the networking mode, the fault handling mode is suitable for instructing the DC power transmission power of the DC power transmitted by the sending-end converter station to the receiving-end converter station to be reduced to a target DC output power value.

[0117] In an optional implementation manner, the target DC output power value Ppu Determined by the following formula:

[0118] P pu =U ac,pu +0.5

[0119] Among them, U ac,pu It is the per-unit value of the positive sequence component of the three-phase voltage.

[0120] In an optional implementation, the mode of the AC side includes an island mode, and the sending-end converter station is pre-connected to at least one sending-end energy consumption device that is turned off by default;

[0121] When the mode on the AC side is the island mode, the fault handling mode is suitable for instructing the sending-end converter station to control at least part of the at least one sending-end energy-consuming device to start and maintain operation, so that the sending-end energy-consuming device that is turned on and running continues to consume the AC power from the sending-end converter station.

[0122] In an optional implementation, the total capacity of the sending-end energy-consuming device that is turned on and running is calculated based on the per-unit value of the drop of the positive-sequence component of the three-phase voltage.

[0123] In an optional implementation manner, the receiving-end converter station is further configured as follows:

[0124] After the first fault condition is met, when it is detected that the electrical parameter information meets the first fault relief condition, controlling the receiving-end energy consumption device to shut down;

[0125] After the second fault condition is met, when it is detected that the electrical parameter information meets the second fault removal condition, the receiving-end energy consumption device is controlled to be turned off, and a fault removal instruction is sent to the sending-end converter station, wherein the fault removal instruction is suitable for instructing the sending-end converter station to exit the fault handling mode.

[0126] Two specific embodiments are provided below.

[0127] Example 1

[0128] Based on a typical ±800kV / 8GW ultra-high voltage flexible direct current transmission system, its main circuit parameters are as follows: submodule rated working voltage 2.0kV, submodule capacitance 24mF, bridge arm reactor 25mH, current limiting reactor 300mH. The length of the direct current transmission line is 2400km, using 6 split conductors, and the line resistance is about 10Ω. The ultra-high voltage flexible direct current transmission system adopts a true bipolar wiring scheme, each pole is cascaded by two valve groups, and the DC voltage of each valve group is 400kV. The valve group adopts a full half-bridge hybrid module, and the full bridge ratio is 60%. The inter-station communication delay of the flexible direct current system is 30ms. The AC side of the sending end converter station is in networking mode, the sending end adopts a fixed active power and fixed reactive power control strategy, and the receiving end adopts a fixed DC voltage and fixed reactive power control strategy. A 4GW DC energy consumption device is configured on the DC side of the receiving converter station, of which 2GW is configured between the positive pole line and the neutral line, and the other 2GW is configured between the negative pole line and the neutral line. Figure 2A shown.

[0129] Before the fault occurs, the UHV flexible DC transmission system operates at full capacity. Figure 3 As shown in 5.1s), a two-phase metallic grounding fault occurs on the AC side of the receiving-end converter transformer, and the positive-sequence component of the three-phase voltage drops to 0.33pu. About 10ms after the fault, the receiving-end converter station detects the fault and immediately puts the DC energy consumption device into operation. At the same time, it notifies the sending-end converter station to reduce the power through inter-station communication, and the power command is 0.83pu. About 40ms after the fault, the sending-end converter station immediately reduces the active power to 0.83pu after receiving the power reduction command through inter-station communication. About 100ms after the fault, the AC side fault of the receiving-end converter transformer is cleared, and the positive-sequence component of the three-phase voltage is increased to 1pu. About 110ms after the fault, the receiving-end converter station detects that the AC side fault is cleared, exits the DC energy consumption device, and at the same time notifies the sending-end converter station to restore the DC power to the previous value through inter-station communication. About 140ms after the fault, the sending-end converter station receives the power command through inter-station communication and restores the DC power to 1pu. As shown in Figure 3 As shown, about 350ms after the fault, the voltage, current and power on the DC pole line basically return to the operating state before the fault. Figure 4 is the maximum voltage of the converter valve submodule of the receiving station during the fault ride-through period, which does not exceed 2.7 kV and is lower than the overvoltage protection setting of the submodule. It can be seen that the method provided by this embodiment can achieve system fault ride-through after a fault occurs on the AC side of the receiving-end converter transformer.

[0130] Example 2

[0131] Based on a typical ±800kV / 8GW ultra-high voltage flexible direct current transmission system, its main circuit parameters are as follows: submodule rated working voltage 2.0kV, submodule capacitance 24mF, bridge arm reactor 25mH, current limiting reactor 300mH. The length of the direct current transmission line is 2400km, using 6 split conductors, and the line resistance is about 10Ω. The ultra-high voltage flexible direct current transmission system adopts a true bipolar wiring scheme, each pole is cascaded by two valve groups, and the DC voltage of each valve group is 400kV. The valve group adopts a full half-bridge hybrid module, and the full bridge ratio is 60%. The inter-station communication delay of the flexible direct current system is 30ms. The AC side of the sending end converter station is an island mode, the sending end adopts a fixed AC voltage amplitude and fixed AC frequency control strategy, and the receiving end adopts a fixed DC voltage and fixed reactive power control strategy. A 4GW DC energy consumption device is configured on the DC side of the receiving end converter station, of which 2GW is configured between the positive pole line and the neutral line, and the other 2GW is configured between the negative pole line and the neutral line. A 4GW AC energy consumption device is configured on the AC side of the sending end converter station, such as Figure 2B shown.

[0132] Before the fault occurs, the UHV flexible DC transmission system operates at full capacity. Figure 5 As shown in 5.1s), a two-phase metallic grounding fault occurs on the AC side of the receiving-end converter transformer, and the positive-sequence component of the three-phase voltage drops to 0.33pu. About 10ms after the fault, the receiving-end converter station detects the fault and immediately starts the DC energy consumption device. At the same time, it notifies the sending-end converter station to start the AC energy consumption device through inter-station communication. The number of AC energy consumption devices put into operation is 3 groups. About 40ms after the fault, the sending-end converter station receives the instruction to start the AC energy consumption device through inter-station communication, and immediately starts 3 groups of AC energy consumption devices. About 100ms after the fault, the AC side fault of the receiving-end converter transformer is cleared, and the positive-sequence component of the three-phase voltage increases to 1pu. About 110ms after the fault, the receiving-end converter station detects that the AC side fault is cleared, and then exits the DC energy consumption device. At the same time, it notifies the sending-end converter station to exit the AC energy consumption device through inter-station communication. About 140ms after the fault, the sending-end converter station receives the instruction to exit the AC energy consumption device through inter-station communication, and then exits all AC energy consumption devices. As shown in Figure 5 As shown, about 350ms after the fault, the voltage, current and power on the DC pole line basically return to the operating state before the fault. Figure 6 is the maximum voltage of the converter valve submodule of the receiving station during the fault ride-through period, which does not exceed 2.7 kV and is lower than the overvoltage protection setting of the submodule. It can be seen that the method provided by this embodiment can achieve system fault ride-through after a fault occurs on the AC side of the receiving-end converter transformer.

[0133] In a third aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of any of the methods described above are implemented.

[0134] In a fourth aspect, an embodiment of the present application provides a computer device, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the steps of any of the methods described above when executing the computer program.

[0135] See also Figure 7 The computer device of this embodiment includes: a processor 701, a memory 702, and a computer program stored in the memory 702 and executable on the processor 701, such as a fault control program. When the processor 701 executes the computer program, the steps in the above-mentioned various fault control method embodiments are implemented.

[0136] Exemplarily, the computer program may be divided into one or more modules / units, which are stored in the memory 702 and executed by the processor 701 to complete the present application. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, which are used to describe the execution process of the computer program in the computer device.

[0137] The computer device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The computer device may include, but is not limited to, a processor 701 and a memory 702. Those skilled in the art will appreciate that the schematic diagram is merely an example of a computer device and does not constitute a limitation on the computer device. The computer device may include more or fewer components than shown in the diagram, or may combine certain components, or different components. For example, the computer device may also include input and output devices, network access devices, buses, etc.

[0138] The processor 701 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor 701 may also be any conventional processor, etc. The processor 701 is the control center of the computer device, and uses various interfaces and lines to connect various parts of the entire computer device.

[0139] The memory 702 can be used to store the computer program and / or module, and the processor 701 realizes various functions of the computer device by running or executing the computer program and / or module stored in the memory 702, and calling the data stored in the memory 702. The memory 702 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory 702 can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0140] Wherein, if the module / unit integrated in the computer device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor 701. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0141] In summary, the embodiments of the present application have at least the following beneficial effects:

[0142] According to the embodiment of the present application, the ultra-high voltage flexible direct current transmission system has a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, the sending-end converter station is configured to transmit direct current to the receiving-end converter station, the receiving-end energy consumption device is closed by default and pre-connected to the receiving-end converter station, the receiving-end energy consumption device is suitable for consuming at least part of the direct current during operation, the at least part of the direct current refers to at least part of the direct current transmitted to the receiving-end converter station, the method is executed by the receiving-end converter station and includes: when it is detected that the electrical parameter information on the AC side of the receiving-end converter station meets the first When a fault condition occurs, the receiving-end energy-consuming device is controlled to start and maintain operation; when it is detected that the electrical parameter information meets the second fault condition, the receiving-end energy-consuming device is controlled to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, a corresponding control instruction is sent to the sending-end converter station, so that the sending-end converter station enters the corresponding fault handling mode; wherein the fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition, thereby improving the safety and economy of the ultra-high voltage flexible direct current transmission system.

[0143] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present application can be implemented by means of software plus the necessary hardware platform, and of course, it can also be implemented entirely by hardware. Based on such an understanding, all or part of the contribution of the technical solution of the present application to the background technology can be embodied in the form of a software product, and the computer software product can be stored in a storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

[0144] The above is a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A fault control method applicable to a UHV flexible DC transmission system, characterized in that: The ultra-high voltage flexible direct current power transmission system comprises a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, wherein the receiving-end energy consumption device is adapted to consume at least part of the direct current during operation, wherein the at least part of the direct current refers to at least part of the direct current transmitted to the receiving-end converter station, and the method is executed by the receiving-end converter station and comprises: When it is detected that the electrical parameter information on the AC side of the receiving-end converter station meets the first fault condition, controlling the receiving-end energy consumption device to start and maintain operation; When it is detected that the electrical parameter information meets the second fault condition, the receiving-end energy consumption device is controlled to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, a corresponding control instruction is sent to the sending-end converter station, so that the sending-end converter station enters a corresponding fault processing mode; The fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition.

2. The method according to claim 1, characterized in that The electrical parameter information includes the three-phase voltage on the AC side of the receiving-end converter station; The first fault condition includes that the positive sequence component of the three-phase voltage is in a first set interval; The second fault condition includes that the positive sequence component of the three-phase voltage is in a second set interval; The lower boundary of the first setting interval and the upper boundary of the second setting interval are equal, both of which are setting voltage thresholds, the first setting interval includes the setting voltage threshold and the second setting interval does not include the setting voltage threshold.

3. The method according to claim 2, characterized in that The mode of the AC side includes a networking mode; When the mode of the AC side is the networking mode, the fault handling mode is suitable for instructing the DC power transmission power of the DC power transmitted by the sending-end converter station to the receiving-end converter station to be reduced to a target DC output power value.

4. The method according to claim 3, characterized in that The target DC output power value P pu Determined by the following formula: P pu =U ac,pu +0.5 Among them, U ac,pu It is the per-unit value of the positive sequence component of the three-phase voltage.

5. The method according to claim 2, characterized in that The mode of the AC side includes an island mode, and the sending-end converter station is pre-connected with at least one sending-end energy-consuming device that is turned off by default; When the mode on the AC side is the island mode, the fault handling mode is suitable for instructing the sending-end converter station to control at least part of the at least one sending-end energy-consuming device to start and maintain operation, so that the sending-end energy-consuming device that is turned on and running continues to consume the AC power from the sending-end converter station.

6. The method according to claim 5, characterized in that The total capacity of the sending-end energy-consuming device that is turned on and running is calculated based on the per-unit value dropped by the positive-sequence component of the three-phase voltage.

7. The method according to any one of claims 1 to 6, characterized in that: The method further comprises: After the first fault condition is met, when it is detected that the electrical parameter information meets the first fault relief condition, controlling the receiving-end energy consumption device to shut down; After the second fault condition is met, when it is detected that the electrical parameter information meets the second fault removal condition, the receiving-end energy consumption device is controlled to be turned off, and a fault removal instruction is sent to the sending-end converter station, wherein the fault removal instruction is suitable for instructing the sending-end converter station to exit the fault handling mode.

8. A UHV flexible DC power transmission system, characterized in that: The ultra-high voltage flexible direct current power transmission system comprises a receiving-end converter station, a sending-end converter station and a receiving-end energy consumption device, wherein the receiving-end energy consumption device is adapted to consume at least part of the direct current during operation, wherein the at least part of the direct current refers to at least part of the direct current transmitted to the receiving-end converter station, and the receiving-end converter station is configured as follows: When it is detected that the electrical parameter information on the AC side of the receiving-end converter station meets the first fault condition, controlling the receiving-end energy consumption device to start and maintain operation; When it is detected that the electrical parameter information meets the second fault condition, the receiving-end energy consumption device is controlled to start and maintain operation, and, according to the mode of the AC side of the sending-end converter station, a corresponding control instruction is sent to the sending-end converter station, so that the sending-end converter station enters a corresponding fault processing mode; The fault severity indicated by the second fault condition is higher than the fault severity indicated by the first fault condition.

9. The system according to claim 8, characterized in that The receiving-end converter station comprises: a first valve group, a first end of which is electrically connected to the positive pole line of the receiving-end converter station, and a second end of which is electrically connected to the AC system; a second valve group, wherein a first end is electrically connected to a third end of the first valve group, a second end is electrically connected to the AC system, and a third end is electrically connected to a neutral line of the receiving-end converter station; A third valve group, a first end of which is electrically connected to the neutral line of the receiving-end converter station, and a second end of which is electrically connected to the AC system; and a fourth valve group, a first end of which is electrically connected to the third end of the third valve group, a second end of which is electrically connected to the AC system, and a third end of which is electrically connected to the negative pole line of the receiving-end converter station; Wherein, the two ends of the sending-end converter station are electrically connected to the positive pole line and the negative pole line of the receiving-end converter station respectively.

10. The system according to claim 9, characterized in that The receiving end energy consumption device comprises: A first DC energy consumption module, two ends of which are electrically connected to the positive pole line and the neutral line of the receiving-end converter station respectively; and The second DC energy consumption module has two ends electrically connected to the neutral line and the negative pole line of the receiving-end converter station respectively.

11. The system according to claim 9, characterized in that At least one of the first valve group, the second valve group, the third valve group, and the fourth valve group adopts a full half-bridge hybrid module structure.

12. The system of claim 8, wherein: The electrical parameter information includes the three-phase voltage on the AC side of the receiving-end converter station; The first fault condition includes that the positive sequence component of the three-phase voltage is in a first set interval; The second fault condition includes that the positive sequence component of the three-phase voltage is in a second set interval; The lower boundary of the first setting interval and the upper boundary of the second setting interval are equal, both of which are setting voltage thresholds, the first setting interval includes the setting voltage threshold and the second setting interval does not include the setting voltage threshold.

13. The system of claim 12, wherein: The mode of the AC side includes a networking mode; When the mode of the AC side is the networking mode, the fault handling mode is suitable for instructing the DC power transmission power of the DC power transmitted by the sending-end converter station to the receiving-end converter station to be reduced to a target DC output power value.

14. The system of claim 13, wherein: The target DC output power value P pu Determined by the following formula: P pu =U ac,pu +0.5 Among them, U ac,pu It is the per-unit value of the positive sequence component of the three-phase voltage.

15. The system of claim 12, wherein: The mode of the AC side includes an island mode, and the sending-end converter station is pre-connected with at least one sending-end energy-consuming device that is turned off by default; When the mode on the AC side is the island mode, the fault handling mode is suitable for instructing the sending-end converter station to control at least part of the at least one sending-end energy-consuming device to start and maintain operation, so that the sending-end energy-consuming device that is turned on and running continues to consume the AC power from the sending-end converter station.

16. The system of claim 15, wherein: The total capacity of the sending-end energy-consuming device that is turned on and running is calculated based on the per-unit value dropped by the positive-sequence component of the three-phase voltage.

17. The system according to any one of claims 8 to 16, characterized in that: The receiving-end converter station is further configured as: After the first fault condition is met, when it is detected that the electrical parameter information meets the first fault relief condition, controlling the receiving-end energy consumption device to shut down; After the second fault condition is met, when it is detected that the electrical parameter information meets the second fault removal condition, the receiving-end energy consumption device is controlled to be turned off, and a fault removal instruction is sent to the sending-end converter station, wherein the fault removal instruction is suitable for instructing the sending-end converter station to exit the fault handling mode.

18. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

19. A computer device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the method according to any one of claims 1 to 7 when executing the computer program.

Images