Protection control method, system, equipment and medium under single-pole locking fault

Abstract

The invention discloses a protection control method, system, equipment and medium under a single-pole locking fault, the protection control method under the single-pole locking fault adopts a main protection strategy and a backup protection strategy, the main protection control is a protection control strategy based on a communication system, and the backup protection control is a protection control strategy based on a frequency signal. Extreme conditions such as communication system faults and the like can be fully considered, dual protection of the single-pole locking faults of the sending-end converter station is realized, and the protection reliability is greatly improved. Therefore, the problem that the reliability of a sending end system is poor after a single-pole locking fault when a communication system goes wrong due to the fact that backup control when the communication system goes wrong is not considered in a current control strategy is solved.

Description

Technical Field

[0001] The present application relates to the technical field of new energy direct current transmission engineering, and in particular to a protection control method, system, equipment and medium under a single-pole locking fault. Background Art

[0002] At present, most new energy units (wind power, photovoltaic) adopt grid-following control and require strong supporting power supply to operate. However, deserts, Gobi and wasteland areas are geographically remote, and the local conventional power supply of new energy bases is small and the power grid is weak, so the system is in an unsupported or weakly supported state. Flexible direct current transmission technology based on modular multilevel converter (MMC) has the ability to build a grid and can provide voltage and frequency support for new energy. It is widely used in offshore wind power and onshore new energy island transmission scenarios. Therefore, large-scale new energy bases will become a typical form of new energy development in the desert and wasteland areas through flexible direct current transmission systems (hereinafter referred to as "new energy flexible direct current transmission systems").

[0003] For high-voltage direct current transmission systems, single-pole blocking is one of the common faults. DC line faults, converter station faults, and AC system faults may all lead to single-pole blocking in the DC system. Since the new energy base at the sending end is not connected to the large power grid, the power transmission of the faulty pole is blocked after single-pole blocking, and the power surplus of several thousand megawatts will appear in the sending-end power grid in a short period of time. Studies have shown that if measures are not taken in time after single-pole blocking, a large amount of surplus power will flow into the MMC sound-pole converter station, causing serious overvoltage in the DC system, thereby threatening the safety and stability of the entire sending-end power grid.

[0004] However, there are still many problems in the single-pole lockout fault handling strategy of the flexible direct current transmission system of new energy through photovoltaic. On the one hand, improper control strategy during the single-pole lockout fault will cause low voltage or overvoltage problems in the sending-end new energy power grid; on the other hand, the current control strategy often does not consider the backup control when the communication system fails. Since most of the new energy sending-end power grids are located in remote areas, the communication infrastructure is not perfect, and the reliability of communication is insufficient. When there is a problem with the communication system, the reliability of the sending-end system after the single-pole lockout fault will face a greater risk, which seriously threatens the safe and stable operation of the system. Summary of the invention

[0005] The present application provides a protection control method, system, device and medium under a single-pole lockout fault, which is used to solve the problem that the current control strategy often does not consider the backup control when a communication system fails, resulting in poor system reliability of the sending-end system after a single-pole lockout fault when a problem occurs in the communication system.

[0006] In view of this, the first aspect of the present application provides a protection control method under a single-pole locking fault, which is applied to a new energy flexible direct current transmission system, wherein the new energy flexible direct current transmission system comprises: a sending-end flexible direct current converter station, a communication system, a new energy station, and a plurality of groups of energy dissipation resistors;

[0007] Methods include:

[0008] When a single-pole locking fault is detected, the energy dissipation resistor is put into use, and a power reduction instruction is issued to each of the new energy stations through the communication system;

[0009] In the event of a single-pole latching fault and after After a time delay of , the frequency command value of the flexible direct current system at the sending end is corrected to a frequency signal with specific characteristics;

[0010] The activation status of the main protection control strategy and the backup protection control strategy for power reduction is determined based on whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal.

[0011] Optionally, the method further comprises: determining the activation status of a main protection control strategy and a backup protection control strategy for power reduction according to whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal, and then further comprising:

[0012] The power injected into the sending-end flexible direct current converter station is monitored in real time to obtain the speed at which the new energy station reduces power, and at the same time, the energy dissipation resistors are controlled to exit in groups according to the speed at which the new energy station reduces power.

[0013] Optionally, determining the activation status of the main protection control strategy and the backup protection control strategy for power reduction according to whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal includes:

[0014] When the new energy station cannot receive the power reduction instruction from the communication system, but can determine that a single-pole lockout fault occurs in the DC system based on the frequency signal, the backup protection control strategy is enabled; the backup protection control strategy is: controlling the unit of the new energy station to reduce to a preset power value based on the received frequency signal.

[0015] Optionally, the determining the activation status of the main protection control strategy and the backup protection control strategy for power reduction according to whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal further includes:

[0016] When the new energy station receives the power reduction instruction from the communication system, the preset main protection control strategy is enabled and the backup protection control strategy is turned off; the main protection control strategy is: controlling the new energy station to reduce power according to the power reduction instruction.

[0017] Optionally, the number of groups of the energy dissipation resistors is determined according to the relationship between the bipolar power before the fault and the maximum power that can be transmitted by a healthy pole.

[0018] Optionally, the number of groups of the energy dissipation resistors put into use is determined according to the relationship between the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole, including:

[0019] When the bipolar power before the fault is greater than the maximum power that can be transmitted by the healthy pole, the number of groups N of energy-discharging resistors put into operation is:

[0020] ;

[0021] In the formula, is the bipolar power before the fault, is the maximum power that can be transmitted by the sound pole, is the round-up symbol, It is the power consumed by a single group of energy dissipation resistors.

[0022] Optionally, the number of groups of the energy dissipation resistors is determined according to the relationship between the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole, and further includes:

[0023] When the bipolar power before the fault is not greater than the maximum power that can be transmitted by the healthy pole, the energy dissipation resistor is not used, and the fault crossing is achieved by transferring the power of the healthy pole.

[0024] Optionally, the process of generating the power reduction instruction includes:

[0025] The distribution is performed based on the relationship between the initial operating power of each of the new energy stations, the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole. The expression is:

[0026] ;

[0027] In the formula, The power reduction size allocated to the i-th new energy station, is the initial operating power of the i-th new energy station, is the bipolar power before the fault, is the maximum power that can be transmitted by the sound pole.

[0028] Optionally, the frequency signal includes:

[0029] Duration is The frequency is higher than the rated value The frequency square wave signal of , where the expression of the frequency signal f is;

[0030] ;

[0031] In the formula, It is the initial frequency of the power grid at the renewable energy sending end.

[0032] Optionally, the main protection control strategy includes:

[0033] go through After a time, controlling the new energy station to reduce power according to the power reduction instruction;

[0034] in, ;

[0035] In the formula, It is the time delay of the measuring instrument when measuring power. is the capacity of a single group of energy dissipation resistors, is the bipolar power before the fault, is the maximum power that can be transmitted by the sound pole.

[0036] Optionally, The size is and the maximum value of the action delay time from the sending-end flexible DC converter station sending information to the new energy station receiving the information.

[0037] Optionally, it also includes:

[0038] The frequency of the new energy transmitted through the flexible DC transmission system is monitored in real time by the new energy station. When a short-term frequency rise occurs, The time monitoring lasts for The square wave signal with a frequency of milliseconds is used to determine whether a single-pole locking fault has occurred at the sending end.

[0039] A second aspect of the present application provides a single-pole locking fault protection control device, which is applied to a new energy flexible direct current transmission system, wherein the new energy flexible direct current transmission system comprises: a sending-end flexible direct current converter station, a communication system, a new energy station, and a plurality of groups of energy dissipation resistors;

[0040] The device includes:

[0041] A first control module is used to, when a single-pole locking fault is detected, put the energy dissipation resistor into operation and issue a power reduction instruction to each of the new energy stations through the communication system;

[0042] The second control module is used to After a time delay of , the frequency command value of the flexible direct current system at the sending end is corrected to a frequency signal with specific characteristics;

[0043] The third control module is used to determine the activation status of the main protection control strategy and the backup protection control strategy for power reduction based on whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal.

[0044] Optionally, it further includes: a fourth control module;

[0045] The fourth control module is used to monitor the power injected into the sending-end flexible DC converter station in real time to obtain the speed at which the new energy station reduces power, and at the same time control the energy dissipation resistors to exit in groups according to the speed at which the new energy station reduces power.

[0046] A third aspect of the present application provides a single-pole locking fault protection control device, the device comprising a processor and a memory:

[0047] The memory is used to store program code and transmit the program code to the processor;

[0048] The processor is used to execute the steps of the protection control method under a single-pole locking fault as described in the first aspect according to the instructions in the program code.

[0049] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program codes, and the program codes are used to execute the protection control method under the single-pole lockout fault described in the first aspect above.

[0050] It can be seen from the above technical solutions that this application has the following advantages:

[0051] The present application provides a protection control method under a single-pole locking fault, which adopts a two-part strategy of main protection and backup protection, wherein the main protection control is a protection control strategy based on the communication system, and the backup protection control is a protection control strategy based on the frequency signal, which can fully consider extreme situations such as communication system failures, realize dual protection of single-pole locking faults at the sending-end converter station, and greatly improve the reliability of protection. This solves the problem that the current control strategy often does not consider the backup control when the communication system fails, resulting in poor reliability of the sending-end system after the single-pole locking fault when the communication system has problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A flow chart of a protection control method under a single-pole locking fault provided in an embodiment of the present application;

[0053] Figure 2A schematic diagram of a new energy flexible direct current transmission system provided in an embodiment of the present application;

[0054] Figure 3 A schematic diagram of a frequency signal reference value of a sending-end flexible direct current converter station provided in an embodiment of the present application;

[0055] Figure 4 A timing logic diagram of a control system under a single-pole locking fault of a sending-end power grid in the first case provided in an embodiment of the present application;

[0056] FIG5 (a) is a waveform diagram of the instantaneous voltage value of the sending-end power grid under a single-pole blocking fault in the first case provided in an embodiment of the present application;

[0057] FIG5( b ) is a waveform diagram of the total active power injected into the sending-end converter station and the active power consumed by the energy dissipation resistor in the first case provided in an embodiment of the present application;

[0058] FIG5( c ) is a waveform diagram of the switching condition of the energy dissipation resistor in the first case provided in an embodiment of the present application;

[0059] Figure 6 A timing logic diagram of a control system under a single-pole locking fault of a sending-end power grid in the second case provided in an embodiment of the present application;

[0060] FIG. 7 ( a ) is a waveform diagram of the instantaneous voltage value of the sending-end power grid under a single-pole blocking fault in the second case provided in an embodiment of the present application;

[0061] FIG7( b ) is a waveform diagram of the total active power injected into the sending-end converter station and the active power consumed by the energy dissipation resistor in the second case provided in an embodiment of the present application;

[0062] FIG7 (c) is a waveform diagram of the switching condition of the energy dissipation resistor in the second case provided in an embodiment of the present application;

[0063] Figure 8 It is a structural schematic diagram of a single-pole locking fault protection control system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0064] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings 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] See also Figure 1A single-pole locking fault protection control method provided in an embodiment of the present application is applied to a new energy flexible DC transmission system, such as Figure 2 As shown, the new energy transmission system via flexible direct current includes: a sending-end flexible direct current converter station, a communication system, a new energy station and several groups of energy dissipation resistors.

[0066] Methods include:

[0067] Step 101: When a single-pole locking fault is detected, the energy dissipation resistor is put into operation, and a power reduction instruction is issued to each new energy station through the communication system.

[0068] It should be noted that if Figure 2 As shown ( Figure 2 For large-scale renewable energy power generation bases, namely renewable energy stations, after the sending-end flexible DC converter station detects that a single-pole locking fault occurs in the renewable energy transmission system through the flexible DC transmission system, the sending-end flexible DC converter station puts into use a discharge resistor of a given capacity and at the same time issues a power reduction instruction to each renewable energy station through the communication system.

[0069] In one embodiment, before step 101, the method further includes:

[0070] The frequency of the flexible DC transmission system of renewable energy is monitored in real time by the renewable energy station. When a short-term frequency rise occurs, The time monitoring lasts for The square wave signal with a frequency of milliseconds is used to determine whether a single-pole locking fault has occurred at the sending end.

[0071] In one embodiment, the number of groups of energy dissipation resistors put into use is determined according to the relationship between the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole, specifically including:

[0072] When the bipolar power before the fault is not greater than the maximum power that can be transmitted by the healthy pole, the energy dissipation resistor is not used, and the fault crossing is achieved by transferring the healthy pole power.

[0073] When the bipolar power before the fault is greater than the maximum power that can be transmitted by the healthy pole, the number of groups N of energy-discharging resistors put into operation is:

[0074] ;

[0075] In the formula, is the bipolar power before the fault, is the maximum power that a sound pole can transmit, is the round-up symbol, It is the power consumed by a single set of energy dissipation resistors.

[0076] In one embodiment, the process of generating the power reduction instruction specifically includes:

[0077] The distribution is based on the relationship between the initial operating power of each new energy station, the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole. The expression is:

[0078] ;

[0079] In the formula, The power reduction size allocated to the i-th new energy station, is the initial operating power of the i-th new energy station, is the bipolar power before the fault, The maximum power that a sound pole can transmit.

[0080] Step 102: When a single-pole locking fault occurs and After a time delay, the frequency command value of the sending-end flexible DC system is corrected to a frequency signal with specific characteristics.

[0081] It should be noted that if Figure 2 As shown, at the sending end flexible DC converter station, a single-pole locking fault is detected in the flexible DC transmission system of renewable energy and passes through After a time delay, the sending-end flexible DC converter station corrects the frequency command value of the renewable energy sending-end flexible DC system into a frequency signal with specific characteristics.

[0082] In one embodiment, the frequency signal of the specific characteristics specifically includes: a duration of The frequency is higher than the rated value The frequency square wave signal of , where the expression of the frequency signal f is;

[0083] ;

[0084] in, The size is and the maximum value of the action delay time from the sending end flexible DC converter station sending information to the new energy station receiving the information. For example, when the action delay time from the sending end flexible DC converter station sending information to the new energy station receiving the information is 150ms, The expression is:

[0085] ;

[0086] In the formula, It is the initial frequency of the power grid at the renewable energy sending end.

[0087] It should be noted that the action delay time from the sending-end flexible direct current converter station sending information to the new energy station receiving the information is related to the actual communication distance and the performance of the communication equipment. The example range may be 50-300ms, and the example value may be 150ms.

[0088] It should be noted that the frequency signal with specific characteristics of the present application refers to a frequency signal designed to be different from the original frequency, and this characteristic is known in advance and uniformly by the new energy station and the converter station. When the new energy station detects the frequency characteristic, it can be determined that it is a signal sent by the sending-end flexible direct current converter station to prompt a single-pole locking fault, and then perform corresponding subsequent operations, such as executing a backup protection control strategy to control the new energy station unit to reduce to a preset power value, i.e., the description of the following step 1032. It should be further noted that in actual applications, the new energy station measures through the frequency measurement device equipped by itself, so that when a communication system fails, the new energy station can monitor the frequency signal with specific characteristics through the frequency measurement device equipped by itself to determine the operating status of the new energy transmission system through the flexible direct current.

[0089] Step 103: Determine the activation status of the main protection control strategy and the backup protection control strategy for power reduction based on whether the new energy station receives the power reduction instruction from the communication system and in combination with the frequency signal.

[0090] In one embodiment, step 103 includes:

[0091] Step 1031: When the new energy station receives a power reduction instruction from the communication system, the main protection control strategy is enabled and the backup protection control strategy is disabled. The main protection control strategy is: controlling the new energy station to reduce power according to the power reduction instruction.

[0092] In one embodiment, the main protection control strategy is specifically:

[0093] go through After a certain time, the power reduction command is used to control the new energy station to reduce power;

[0094] in, ;

[0095] In the formula, It is the time delay of the measuring instrument when measuring power. is the capacity of a single set of energy dissipation resistors, is the bipolar power before the fault, The maximum power that a sound pole can transmit.

[0096] Step 1032: When the new energy station cannot receive the power reduction instruction from the communication system, but can determine that a single-pole locking fault occurs in the DC system based on the frequency signal, the backup protection control strategy is enabled. The backup protection control strategy is: control the units of the new energy station to reduce to a preset power value based on the received frequency signal.

[0097] It should be noted that the control of the units of the new energy station in step 1032 to reduce to a preset power value can be specifically to control the units of the new energy station to reduce the power by half. It can be understood that this application is based on the full power of the new energy station. When the power is reduced by half, it is equivalent to the power sent to the sending end converter station just becoming a single-pole power. Regardless of whether the new energy station is fully powered, reducing it to 50% of the initial value can cross the fault.

[0098] Furthermore, in one embodiment, after step 103, the following steps are further included:

[0099] The power injected into the sending-end flexible DC converter station is monitored in real time to obtain the speed at which the new energy station reduces power. At the same time, the energy discharge resistors are controlled to exit in groups according to the speed at which the new energy station reduces power.

[0100] In one embodiment, in step 103, the energy dissipation resistor is controlled to exit in groups according to the speed at which the new energy station reduces power, which specifically includes:

[0101] The active power injected into the AC bus of the converter station is monitored in real time. Whenever the power consumed by a group of energy-discharging resistors is reduced, a group of energy-discharging resistors is controlled to exit.

[0102] The following is a specific example of a protection control method under a single-pole locking fault provided in an embodiment of the present application:

[0103] The first case: Figure 4 As shown, the communication system is intact, the main protection control strategy works, and the backup protection control strategy does not work:

[0104] At 1.0s, the single pole of the sending end converter station is locked. According to the bipolar power of 10000MW before the fault and the maximum power of MMC single pole transmission of 5000MW, the number of groups of energy-discharging resistors to be put into use is calculated to be 10. The total power required to be reduced by the sending end new energy grid is 5000MW, and the power reduction share allocated to each new energy station is calculated to be 50% of their respective initial power. Then, according to the capacity of a single group of energy-discharging resistors and the measurement time delay, the power reduction speed of new energy is calculated. The time interval is 200ms, that is, the renewable energy reduces the power to 50% in 200ms. At 1.002s, the sending end converter station puts in 5000MW AC energy dissipation resistor. At 1.030s, the sending end flexible direct current station changes the frequency signal reference value (such as Figure 3The frequency signal is changed to 50.35Hz at 1.200s, and a square wave signal of 50.35Hz with a duration of 170 milliseconds is generated. The frequency signal is then changed to 50Hz at 1.15s. At 1.17s, the total power of the photovoltaic station is reduced by 500MW, and the energy dissipation resistor withdraws from the capacity of one group. Thereafter, for every 500MW reduction in the total power of the photovoltaic station at the sending end, the energy dissipation resistor withdraws from one group.

[0105] Figure 5(a)-Figure 5(c) The instantaneous value of voltage under a single-pole blocking fault in the sending-end power grid in the first case, the total active power injected into the sending-end converter station, the active power consumed by the energy-discharging resistor, and the switching status of the energy-discharging resistor are displayed.

[0106] The second case: Figure 6 As shown, the communication system fails, the main protection control strategy does not work, and the backup protection control strategy works:

[0107] At 1.0s, the single pole of the sending end converter station is locked. According to the bipolar power of 10000MW before the fault and the maximum power of MMC single pole transmission of 5000MW, the number of groups of energy-discharging resistors to be put into use is calculated to be 10. The total power required to be reduced by the sending end new energy grid is 5000MW, and the power reduction share allocated to each new energy station is calculated to be 50% of their respective initial power. Then, according to the capacity of a single group of energy-discharging resistors and the measurement time delay, the power reduction speed of new energy is calculated. The time interval is 200ms, that is, the renewable energy reduces the power to 50% in 200ms. At 1.002s, the sending end converter station puts in 5000MW AC energy dissipation resistor. At 1.030s, the sending end flexible direct current station changes the frequency signal reference value (such as Figure 3 As shown in the figure, the frequency of the PV station is modified to 50.35Hz, generating a 50.35Hz square wave signal with a duration of 170 milliseconds, until 1.200s when the frequency signal is modified to 50Hz. At 1.270s, the stabilization control device on the new energy station side still has not received the unipolar blocking signal from the communication system, but has detected two frequency pulses, and the fault judgment of the unipolar blocking is completed through the frequency signal. When the new energy completes the fault judgment of the unipolar blocking, it sends a power reduction signal for the new energy station. The control system determines that the communication system is faulty, the main protection fails, and the new energy station enables the backup protection control. All photovoltaic stations reduce their respective power by half in 200ms. Thereafter, for every 500MW reduction in the total power of the photovoltaic station at the sending end, the energy dissipation resistor will exit one group.

[0108] Figure 7(a)-Figure 7(c)The instantaneous value of voltage under a single-pole blocking fault in the sending-end power grid in the second case, the total active power injected into the sending-end converter station, the active power consumed by the energy-discharging resistor, and the switching status of the energy-discharging resistor are displayed.

[0109] The above is a protection control method under a single-pole lockout fault provided in an embodiment of the present application, and the following is a protection control device under a single-pole lockout fault provided in an embodiment of the present application.

[0110] See also Figure 8 A single-pole locking fault protection control device provided in an embodiment of the present application is applied to a new energy flexible direct current transmission system. The new energy flexible direct current transmission system includes: a sending-end flexible direct current converter station, a communication system, a new energy station and several groups of energy dissipation resistors.

[0111] The device includes:

[0112] The first control module 201 is used to put the energy dissipation resistor into operation when a single-pole locking fault is detected, and to issue a power reduction instruction to each new energy station through the communication system.

[0113] The second control module 202 is used to control the After a time delay of

[0114] The third control module 203 determines the activation status of the main protection control strategy and the backup protection control strategy for power reduction based on whether the new energy station receives the power reduction instruction from the communication system and in combination with the frequency signal.

[0115] Furthermore, in one embodiment, the single-pole locking fault protection control device of the present application further includes:

[0116] The fourth control module is used to monitor the power injected into the sending-end flexible direct current converter station in real time to obtain the speed at which the new energy station reduces power, and at the same time control the energy discharge resistors to exit in groups according to the speed at which the new energy station reduces power.

[0117] Furthermore, in an embodiment of the present application, a single-pole locking fault protection control device is provided, the device comprising a processor and a memory:

[0118] The memory is used to store program code and transmit the program code to the processor;

[0119] The processor is used to execute the steps of the protection control method under a single-pole locking fault as described in the above method embodiment according to the instructions in the program code.

[0120] Furthermore, a computer-readable storage medium is provided in an embodiment of the present application, and the computer-readable storage medium is used to store program code, and the program code is used to execute the protection control method under the single-pole lockout fault described in the above method embodiment.

[0121] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here.

[0122] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0123] It should be understood that in this application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0124] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0125] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0126] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0127] If the integrated unit 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 technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (full name in English: Read-Only Memory, English abbreviation: ROM), random access memory (full name in English: Random Access Memory, English abbreviation: RAM), disk or optical disk and other media that can store program codes.

[0128] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A protection control method under a single-pole locking fault, characterized in that: Applied to a new energy flexible direct current transmission system, the new energy flexible direct current transmission system comprising: a sending-end flexible direct current converter station, a communication system, a new energy station and a plurality of groups of energy dissipation resistors; Methods include: When a single-pole locking fault is detected, the energy dissipation resistor is put into use, and a power reduction instruction is issued to each of the new energy stations through the communication system; In the event of a single-pole latching fault and after After a time delay of , the frequency command value of the flexible direct current system at the sending end is corrected to a frequency signal with specific characteristics; The activation status of the main protection control strategy and the backup protection control strategy for power reduction is determined based on whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal.

2. The single-pole locking fault protection control method according to claim 1 is characterized in that: The method further comprises: determining the activation state of the main protection control strategy and the backup protection control strategy for power reduction according to whether the new energy station receives the power reduction instruction transmitted by the communication system and combining the frequency signal; and then further comprising: The power injected into the sending-end flexible direct current converter station is monitored in real time to obtain the speed at which the new energy station reduces power, and at the same time, the energy dissipation resistors are controlled to exit in groups according to the speed at which the new energy station reduces power.

3. The single-pole locking fault protection control method according to claim 1 is characterized in that: The determining, based on whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal, the activation status of the main protection control strategy and the backup protection control strategy for power reduction includes: When the new energy station cannot receive the power reduction instruction from the communication system, but can determine that a single-pole lockout fault occurs in the DC system based on the frequency signal, the backup protection control strategy is enabled; the backup protection control strategy is: controlling the unit of the new energy station to reduce to a preset power value based on the received frequency signal.

4. The single-pole locking fault protection control method according to claim 1 is characterized in that: The determining, based on whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal, the activation state of the main protection control strategy and the backup protection control strategy for power reduction further includes: When the new energy station receives the power reduction instruction from the communication system, the preset main protection control strategy is enabled and the backup protection control strategy is turned off; the main protection control strategy is: controlling the new energy station to reduce power according to the power reduction instruction.

5. The single-pole locking fault protection control method according to claim 1 is characterized in that: The number of groups of the energy dissipation resistors is determined according to the relationship between the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole.

6. The single-pole locking fault protection control method according to claim 5 is characterized in that: The number of groups of energy dissipation resistors put into use is determined according to the relationship between the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole, including: When the bipolar power before the fault is greater than the maximum power that can be transmitted by the healthy pole, the number of groups N of energy-discharging resistors put into operation is: ； In the formula, is the bipolar power before the fault, is the maximum power that can be transmitted by the sound pole, is the round-up symbol, It is the power consumed by a single group of energy dissipation resistors.

7. The single-pole locking fault protection control method according to claim 5 is characterized in that: The number of groups of energy dissipation resistors put into use is determined according to the relationship between the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole, and also includes: When the bipolar power before the fault is not greater than the maximum power that can be transmitted by the healthy pole, the energy dissipation resistor is not used, and the fault crossing is achieved by transferring the power of the healthy pole.

8. The single-pole locking fault protection control method according to claim 1, characterized in that: The process of generating the power reduction instruction includes: The distribution is performed based on the relationship between the initial operating power of each of the new energy stations, the bipolar power before the fault and the maximum power that can be transmitted by the healthy pole. The expression is: ； In the formula, The power reduction size allocated to the i-th new energy station, is the initial operating power of the i-th new energy station, is the bipolar power before the fault, is the maximum power that can be transmitted by the sound pole.

9. The single-pole locking fault protection control method according to claim 1, characterized in that: The frequency signal comprises: Duration is The frequency is higher than the rated value The frequency square wave signal of , where the expression of the frequency signal f is; ； In the formula, It is the initial frequency of the power grid at the renewable energy sending end.

10. The single-pole locking fault protection control method according to claim 1, characterized in that: The main protection control strategy includes: go through After a time, controlling the new energy station to reduce power according to the power reduction instruction; in, ; In the formula, It is the time delay of the measuring instrument when measuring power. is the capacity of a single group of energy dissipation resistors, is the bipolar power before the fault, The maximum power that a sound pole can transmit.

11. The single-pole locking fault protection control method according to claim 10, characterized in that: The size is and the maximum value of the action delay time from the sending-end flexible DC converter station sending information to the new energy station receiving the information.

12. The single-pole locking fault protection control method according to any one of claims 1 to 11, characterized in that: Also includes: The frequency of the new energy transmitted through the flexible DC transmission system is monitored in real time by the new energy station. When a short-term frequency rise occurs, The time monitoring lasts for The square wave signal with a frequency of milliseconds is used to determine whether a single-pole locking fault has occurred at the sending end.

13. A single-pole locking fault protection control device, characterized in that: Applied to a new energy flexible direct current transmission system, the new energy flexible direct current transmission system comprising: a sending-end flexible direct current converter station, a communication system, a new energy station and a plurality of groups of energy dissipation resistors; The device includes: A first control module is used to, when a single-pole locking fault is detected, put the energy dissipation resistor into operation and issue a power reduction instruction to each of the new energy stations through the communication system; The second control module is used to After a time delay of , the frequency command value of the flexible direct current system at the sending end is corrected to a frequency signal with specific characteristics; The third control module is used to determine the activation status of the main protection control strategy and the backup protection control strategy for power reduction based on whether the new energy station receives the power reduction instruction transmitted by the communication system and in combination with the frequency signal.

14. The single-pole locking fault protection control device according to claim 13, characterized in that: Also includes: a fourth control module; The fourth control module is used to monitor the power injected into the sending-end flexible DC converter station in real time to obtain the speed at which the new energy station reduces power, and at the same time control the energy dissipation resistors to exit in groups according to the speed at which the new energy station reduces power.

15. A single-pole locking fault protection control device, characterized in that: The device comprises a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the single-pole lockout fault protection control method described in any one of claims 1-12 according to the instructions in the program code.

16. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the single-pole lockout fault protection control method described in any one of claims 1-12.

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