Control method and apparatus for receiving-end alternating-current fault ride-through, and electronic device and storage medium

Abstract

A control method and apparatus for receiving-end alternating-current fault ride-through, and an electronic device and a storage medium, which relate to the technical field of power transmission and distribution, and are used for solving the technical problems of system power imbalance, poor coordination capability, etc., in existing receiving-end alternating-current fault ride-through processes. The method comprises: determining as a faulty receiving-end converter station a receiving-end converter station in which an alternating-current fault occurs, generating an alternating-current voltage fault signal by means of the faulty receiving-end converter station, and also executing power surplus assessment, in order to obtain a surplus power value; then, transmitting the alternating-current voltage fault signal and the surplus power value to an alternating-current energy consumption apparatus; if the faulty receiving-end converter station is a receiving-end constant-voltage station, on the basis of the alternating-current voltage fault signal and the surplus power value, absorbing surplus power of an islanded power grid by means of putting the alternating-current energy consumption apparatus into use; and if the faulty receiving-end converter station is a receiving-end constant-power station, adjusting, on the basis of the surplus power value, a reference power value of the faulty receiving-end converter station by means of the faulty receiving-end converter station, and absorbing the surplus power of the islanded power grid by means of putting the alternating-current energy consumption apparatus into use.

Description

Receiving-end AC fault ride-through control method, device, electronic device, and storage medium

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 8, 2023, with application number 202311478671.4 and invention name “Receiving-end AC fault ride-through control method, device, electronic device and storage medium”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of power transmission and distribution, and in particular to a receiving-end AC fault ride-through control method, device, electronic equipment and storage medium. Background Art

[0003] With the vigorous development of new energy technologies, more and more new energy-related industries have been put into practical use, especially in the power industry. However, most new energy bases serving as power generation sources are built in remote areas with low load levels and weak grid structures. There is an obvious demand for stable transmission of new energy islands. Among them, flexible direct current transmission has the characteristics of flexibility, controllability and high efficiency, and is one of the important power transmission means for new energy transmission.

[0004] In actual applications, when flexible DC transmission technology is used to connect an island power generation system with a receiving AC power grid, if a fault occurs in the receiving AC power grid, the power cannot be transmitted. If the sending power generation system is not disconnected, a large amount of surplus power will appear in the DC system, causing severe overvoltage in the DC system and endangering the safe operation of the system.

[0005] To address the problem of surplus power in flexible DC systems during faults and enable rapid recovery of DC transmission systems after short-term faults in the receiving grid, a common solution currently used in domestic and international projects is to install DC energy dissipation devices on the DC side of the receiving converter station to dissipate excess power, enabling fault ride-through without disconnecting the islanded generation system at the sending end. This approach is expensive due to the complex structure of the DC energy dissipation devices and the use of a large number of controllable power devices. This is particularly true for the widely used modular DC energy dissipation devices, which feature excellent electromagnetic compatibility and real-time controllable power dissipation. These devices utilize a large number of capacitors, IGBTs (Insulated Gate Bipolar Transistors), diodes, and other components. Furthermore, since each module contains capacitors, voltage balance must be maintained across the capacitors. Therefore, even if the AC grid is not faulty, certain submodule switching operations are still required to ensure capacitor voltage balance. This results in additional losses and can easily lead to power imbalance and poor coordination during the AC fault ride-through process.

[0006] Summary of the Invention

[0007] The present invention provides a receiving-end AC fault ride-through control method, device, electronic device and storage medium, which are used to solve or partially solve technical problems such as system power imbalance and poor coordination ability during the receiving-end AC fault ride-through process of a new energy island ultra-long-distance transmission multi-end system.

[0008] The present invention provides a receiving-end AC fault ride-through control method, which is applied to a receiving-end converter station of a new energy island power grid sending multi-end system, wherein the sending multi-end system further includes an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations. The method comprises:

[0009] If an AC fault is detected, an AC voltage fault signal is generated and a power surplus evaluation is performed to obtain a surplus power value.

[0010] Transmitting the AC voltage fault signal and the surplus power value to the AC energy consuming device, so that the AC energy consuming device absorbs the island voltage surplus power based on the AC voltage fault signal and the surplus power value;

[0011] If a constant power control mode is currently adopted, the power reference value needs to be adjusted according to the surplus power value.

[0012] The present invention also provides a receiving-end AC fault ride-through control method, which is applied to an AC energy consumption device of a new energy island power grid sending multi-terminal system, wherein the sending multi-terminal system further includes at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the method comprises:

[0013] receiving an AC voltage fault signal and a surplus power value transmitted by a receiving-end converter station where an AC fault occurs;

[0014] Based on the AC voltage fault signal and the surplus power value, control is performed to absorb the surplus power of the island power grid.

[0015] The present invention also provides a receiving-end AC fault ride-through control method, which is applied to a sending multi-terminal system of a new energy island power grid. The sending multi-terminal system includes at least an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each sending-end converter station is connected to at least two receiving-end converter stations. The method includes:

[0016] determining the receiving-end converter station where the AC fault is detected as a faulty receiving-end converter station, generating an AC voltage fault signal through the faulty receiving-end converter station, and simultaneously performing a power surplus evaluation to obtain a surplus power value;

[0017] transmitting the AC voltage fault signal and the surplus power value to the AC energy consumption device through the fault receiving end converter station;

[0018] If the fault receiving-end converter station is a receiving-end constant voltage station, absorbing the surplus power of the island power grid through the AC energy consumption device based on the AC voltage fault signal and the surplus power value;

[0019] If the faulty receiving-end converter station is a receiving-end fixed-power station, the power reference value of the faulty receiving-end converter station is adjusted according to the surplus power value by the faulty receiving-end converter station, and the surplus power of the island power grid is absorbed by the AC energy consumption device.

[0020] The present invention also provides a receiving-end AC fault ride-through control device, which is applied to a receiving-end converter station of a new energy island power grid sending multi-end system, wherein the sending multi-end system also includes an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the device includes:

[0021] a first power surplus evaluation module, configured to generate an AC voltage fault signal if an AC fault is detected, and simultaneously perform a power surplus evaluation to obtain a surplus power value;

[0022] a first surplus power value transmission module, configured to transmit the AC voltage fault signal and the surplus power value to the AC energy consuming device, so that the AC energy consuming device absorbs the island voltage surplus power based on the AC voltage fault signal and the surplus power value;

[0023] The power reference value adjustment module is configured to adjust the power reference value according to the surplus power value if a constant power control mode is currently adopted.

[0024] The present invention also provides a receiving-end AC fault ride-through control device, which is applied to an AC energy consumption device of a new energy island power grid sending multi-terminal system, wherein the sending multi-terminal system further includes at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the device includes:

[0025] A surplus power value receiving module is used to receive an AC voltage fault signal and a surplus power value transmitted by a receiving-end converter station where an AC fault occurs;

[0026] The surplus power input module is used to control the input and absorption of the surplus power of the island power grid based on the AC voltage fault signal and the surplus power value.

[0027] The present invention also provides a receiving-end AC fault ride-through control device, which is applied to a sending multi-terminal system of a new energy island power grid. The sending multi-terminal system includes at least an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each sending-end converter station is connected to at least two receiving-end converter stations. The device includes:

[0028] a second power surplus evaluation module, configured to determine a receiving-end converter station where an AC fault is detected as a faulty receiving-end converter station, generate an AC voltage fault signal through the faulty receiving-end converter station, and simultaneously perform power surplus evaluation to obtain a surplus power value;

[0029] a second surplus power value transmission module, configured to transmit the AC voltage fault signal and the surplus power value to the AC energy consuming device via the fault receiving-end converter station;

[0030] a receiving-end constant voltage station control processing module, configured to, if the faulty receiving-end converter station is a receiving-end constant voltage station, absorb the surplus power of the island power grid through the AC energy consumption device based on the AC voltage fault signal and the surplus power value;

[0031] The receiving-end fixed power station control processing module is used to adjust the power reference value of the faulty receiving-end converter station according to the surplus power value through the faulty receiving-end converter station if the faulty receiving-end converter station is a receiving-end fixed power station, and to absorb the surplus power of the island power grid through the AC energy consumption device.

[0032] The present invention further provides an electronic device, comprising a processor and a memory:

[0033] The memory is used to store program code and transmit the program code to the processor;

[0034] The processor is configured to execute any one of the above-described receiving-end AC fault ride-through control methods according to instructions in the program code.

[0035] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program code, and the program code is used to execute the receiving-end AC fault ride-through control method as described in any one of the above items.

[0036] It can be seen from the above technical solutions that the present invention has the following advantages: for the AC fault crossing of the receiving end of the multi-terminal transmission system of a large-scale new energy island at an ultra-long distance, the receiving end converter station where the AC fault is detected is first determined as the fault receiving end converter station, and an AC voltage fault signal is generated. At the same time, a power surplus evaluation is performed to obtain a surplus power value, thereby quickly determining the surplus power to be absorbed, thereby avoiding the problem of voltage output backlog of the new energy electric field; then the AC voltage fault signal and the surplus power value are transmitted to the AC energy consumption device, so that the AC energy consumption device can dissipate and absorb the surplus power based on the AC voltage fault signal and the surplus power value; if the fault receiving end converter station If the converter station is a receiving-end constant voltage station, then based on the AC voltage fault signal and the surplus power value, the AC energy consumption device is used to absorb the surplus power of the island power grid; if the fault receiving-end converter station is a receiving-end constant power station, the power reference value of the fault receiving-end converter station is adjusted according to the surplus power value, and the AC energy consumption device is used to absorb the surplus power of the island power grid. Therefore, when an AC fault occurs, different response measures can be taken for receiving-end converter stations with different control modes, solving the problems of system power imbalance, poor coordination ability and poor recovery characteristics after fault clearing that are prone to occur in the process of riding through the receiving-end AC fault when sending multi-terminal systems at ultra-long distances. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] FIG1a is a schematic structural diagram of a multi-terminal system for transmitting a new energy island power grid according to an embodiment of the present invention;

[0039] FIG1b is a control schematic diagram of a receiving-end flexible power control converter station provided by an embodiment of the present invention;

[0040] FIG2 is a flowchart of a receiving-end AC fault ride-through control method provided by an embodiment of the present invention;

[0041] FIG3 is a schematic diagram of the overall flow of a receiving-end AC fault ride-through control method provided by an embodiment of the present invention;

[0042] FIG4 is a structural block diagram of a receiving-end AC fault ride-through control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] Embodiments of the present invention provide a receiving-end AC fault ride-through control method, device, electronic device, and storage medium, which are used to solve or partially solve technical problems such as system power imbalance and poor coordination ability during the receiving-end AC fault ride-through process of a new energy island ultra-long-distance transmission multi-end system.

[0044] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] As an example, in a new energy island grid system, to address the problem of surplus power in the flexible DC system during faults and enable the DC transmission system to quickly recover after a short-term fault in the receiving grid, a DC energy dissipation device is typically installed on the DC side of the receiving converter station to dissipate excess power, enabling fault ride-through without disconnecting the sending island power generation system. This approach is expensive due to the complex structure of the DC energy dissipation device and the use of a large number of controllable power devices. This is especially true for the widely used modular DC energy dissipation devices, which feature excellent electromagnetic compatibility and real-time controllable power dissipation. These devices utilize a large number of capacitors, IGBTs, diodes, and other components. Furthermore, since each module contains capacitors, voltage balance must be maintained across the capacitors. Therefore, even if the AC grid is not faulty, certain submodule switching operations are still required to ensure capacitor voltage balance. This results in additional losses and can easily lead to power imbalance and poor coordination during the AC fault ride-through process.

[0046] Compared with DC energy-consuming devices, AC energy-consuming devices consisting of thyristors and energy-consuming resistors installed in the AC lines of the sending-end converter station have simpler topology, lower costs, and do not require complex switching control. This can further improve the engineering economy of the flexible DC system operation and is suitable for the isolated island transmission system of land-based new energy bases.

[0047] At present, AC energy-consuming devices are rarely used in the isolated transmission systems of large-scale new energy bases, especially the coordinated control strategies for multi-terminal DC transmission systems are not mature.

[0048] Therefore, one of the core invention points of the embodiment of the present invention is to propose a receiving-end AC fault ride-through control method applicable to a multi-terminal transmission system of a large-scale new energy island at an ultra-long distance. First, in view of the problem that the control of DC energy consumption devices is complex and expensive, an AC energy consumption device is used to replace the DC energy consumption device to ride through the receiving-end AC fault, thereby reducing the system engineering cost and improving the operation economy. Secondly, in view of the problem that the existing AC energy consumption device has insufficient coordination with the multi-terminal DC transmission system, the receiving-end AC fault ride-through is achieved through the coordinated operation between the AC energy consumption device and the multi-terminal DC transmission system. For the difference in AC faults between the receiving-end controlled voltage and the controlled power converter station, different fault The system adopts a ride-through strategy and adjusts the receiving-end power recovery speed in conjunction with the sending-end AC energy consumption removal speed, thereby solving the problems of system power imbalance, poor coordination ability, and poor recovery characteristics after fault clearance that are prone to occur in the receiving-end AC fault ride-through process of the sending multi-end system, avoiding overvoltage lockout of the converter station and equipment overvoltage damage accidents. At the same time, in response to the problem of discontinuous energy consumption capacity in the group configuration of AC energy consumption resistors, a flexible switching strategy is provided to determine the power surplus according to the AC voltage drop during the fault, calculate the number of energy consumption device groups, and flexibly switch the energy consumption groups repeatedly according to the actual power consumption, solving the problem of mismatch between energy consumption power and system surplus power caused by discontinuous AC energy consumption capacity.

[0049] Referring to Figure 1a, a structural schematic diagram of a new energy island power grid transmission multi-terminal system provided by an embodiment of the present invention is shown. The transmission multi-terminal system is suitable for ultra-long-distance transmission control of large-scale new energy islands, wherein the transmission multi-terminal system may at least include a new energy electric field, an AC energy consumption device, and at least one sending-end flexible DC converter station (hereinafter referred to as the sending-end converter station) connected to the AC energy consumption device, wherein each sending-end converter station is connected to at least two receiving-end flexible DC converter stations (hereinafter referred to as the receiving-end converter stations).

[0050] To simplify the display, Figure 1a only shows one converter station structure combination (one sending-end converter station corresponds to at least two receiving-end converter stations) as an illustration. In actual applications, the multi-end sending system may include multiple identical or similar converter station structure combinations. It can be understood that the present invention does not limit this.

[0051] Among them, the AC energy consumption device is equipped with multiple groups of AC energy consumption sub-modules. The AC energy consumption device is used to dissipate the continuous active output of the new energy electric field when the active power transmission channel of the DC line is blocked, so as to avoid overvoltage problems caused by energy accumulation in the sending-end AC feeder.

[0052] The AC energy consumption device is connected to the AC busbar where the sending-end converter station connects to the new energy island power grid. The new energy island power grid is connected to the sending-end converter station through a three-phase AC busbar, and the sending-end converter station is connected to the receiving-end converter station through a bipolar DC overhead line.

[0053] Furthermore, corresponding control strategies can be configured for the sending-end converter station and the receiving-end converter station. Specifically, all sending-end converter stations adopt a dual-closed-loop constant AC voltage-frequency control method. For at least two receiving-end converter stations corresponding to each sending-end converter station, one of the receiving-end converter stations adopts a constant DC voltage control method, and the remaining receiving-end converter stations adopt a constant power control method. At the same time, inter-station optical fiber communication is used for signal transmission between the sending-end converter station, the receiving-end converter station and the AC energy-consuming devices.

[0054] At the same time, AC fault power control is configured for the power receiving end converter station, power parameters during the fault period and power recovery curve during the fault recovery period are set, and a smooth switching slope is set.

[0055] For better explanation, referring to FIG1 b , there is shown a control schematic diagram of a receiving-end flexible-controlled power converter station provided by an embodiment of the present invention.

[0056] Take the case of AC fault requiring power control as an example. When the receiving converter station is in normal operation, its active power is P pre When an AC fault occurs, the power will also decrease due to the voltage drop, down to V m_af is the effective value of the AC side voltage after the fault occurs, V m_pre It is the effective value of the AC side voltage before the fault occurs. At the same time, when the power is detected to be reduced to When the fault power is reached (which can be called fault power), an AC fault signal is generated. The fault power is processed by the smooth switching slope d / dt, and an active power command value is output in combination with the AC fault signal. Then, the active power command value, together with the input active power actual value, reactive power command value and reactive power actual value, is input to the (voltage) outer loop controller for processing.

[0057] The outer loop controller, also known as the voltage outer loop controller, can adjust the voltage output according to the voltage level to maintain voltage stability. Therefore, using an outer loop controller for voltage control can maintain a stable voltage output.

[0058] After being processed by the outer loop controller, a fault current reference value i in the DQ three-dimensional coordinate system can be output sdq_ref , then the fault current reference value i sdq_ref The current is input to the (current) inner loop controller, where the current inner loop controller can adjust the current output according to the current size to maintain the stability of the current.

[0059] At the same time, the three-phase voltage u output by the AC bus in the ABC three-dimensional coordinate system is sabc And the three-phase current isabc It is input into the three-dimensional coordinate transformation process abc-dq, and after the three-dimensional coordinate transformation, the three-phase voltage u corresponding to the DQ coordinate system is output. sdq And the three-phase current i sdq To the inner loop controller, combined with the three-phase voltage u sdq , three-phase current i sdq And the fault current reference value i sdq_ref , can output the fault current reference value i sdq_ref The corresponding control voltage reference value u cdq_ref .

[0060] Then the fault voltage reference value u sdq_ref And the coordinate transformation torque value θ output by the three-dimensional coordinate transformation processing abc-dq m The three-phase control voltage reference value u in the ABC three-dimensional coordinate system is output together with the DC current value output after the DC current controller is limited. cabc_ref , then the three-phase control voltage reference value u cabc_ref Input to PWM (Pulse-width modulation, pulse width modulation) for pulse modulation, output three-phase control voltage reference value u cabc_ref The corresponding trigger signal can trigger the VSC (Voltage Source Converter) to perform power control to reduce the power reference value of the receiving-end fixed power converter station.

[0061] Regarding the power control process after fault recovery, its actual working principle is the same as or similar to the above process, and reference may be made to the relevant process in the above embodiment, which will not be described in detail here.

[0062] Therefore, for the receiving-end fixed-power converter station, through the corresponding configuration of AC fault power control, when a fault occurs or after the fault is restored, according to the corresponding power parameters or power switching curve, when reducing or increasing the power, smooth power switching can be achieved, thereby maximizing the protection of the stable operation of various functional modules in the receiving-end fixed-power converter station.

[0063] In an embodiment of the present invention, a multi-terminal transmission system suitable for ultra-long-distance transmission control of large-scale new energy islands is provided. In this system, by adopting an AC energy consumption device instead of a DC energy consumption device to cross the receiving-end AC fault, the system engineering cost is greatly reduced and the operating economy is improved. At the same time, by cooperating with the receiving-end AC fault crossing control method provided in an embodiment of the present invention, the problems of system power imbalance, poor coordination ability and poor recovery characteristics after fault clearing that are prone to occur in the multi-terminal transmission system during the receiving-end AC fault crossing process can be solved, thereby avoiding the occurrence of overvoltage lockout of the converter station and overvoltage damage accidents of equipment.

[0064] 2 , there is shown a flowchart of a receiving-end AC fault ride-through control method provided by an embodiment of the present invention. The method is applied to a sending multi-terminal system of a new energy island power grid. The sending multi-terminal system includes at least an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each sending-end converter station is connected to at least two receiving-end converter stations. The method may specifically include the following steps:

[0065] Step 201: Determine the receiving-end converter station where the AC fault is detected as the faulty receiving-end converter station, generate an AC voltage fault signal through the faulty receiving-end converter station, and simultaneously perform power surplus evaluation to obtain a surplus power value;

[0066] In practical applications, the AC voltage of the receiving converter station can be detected in real time, and whether an AC fault occurs can be determined based on the effective value of the AC voltage. If an AC fault occurs, an AC voltage fault signal U can be generated through the receiving converter station where the fault occurs. low , and perform power surplus evaluation based on power variation.

[0067] Furthermore, a power surplus evaluation is performed to obtain a surplus power value. The surplus power value corresponding to the fault receiving converter station can be calculated using the following formula:

[0068] Where f is the surplus power value, V m_af is the effective value of the AC side voltage after the fault occurs, V m_pre is the effective value of the AC side voltage before the fault occurs, P pre is the active power before the fault occurs.

[0069] Therefore, through real-time monitoring of AC voltage, it is possible to promptly detect whether an AC fault occurs at the receiving converter station. After an AC fault occurs, a fault signal representing the AC voltage fault can be generated to trigger the AC energy consumption device to dissipate power. At the same time, through power surplus assessment, the surplus power that needs to be absorbed can be quickly determined to avoid the problem of voltage output backlog in the new energy power field.

[0070] Step 202: transmitting the AC voltage fault signal and the surplus power value to the AC energy consumption device through the fault receiving-end converter station;

[0071] Then the fault receiving converter station can send the AC voltage fault signal U low The surplus power value f is transmitted to the AC energy consuming device at the sending end, so that the AC energy consuming device can be used to generate the AC voltage fault signal U low And the surplus power value f is used to dissipate and absorb the surplus power.

[0072] Step 203: If the fault receiving-end converter station is a receiving-end constant voltage station, absorbing the surplus power of the island power grid through the AC energy consumption device based on the AC voltage fault signal and the surplus power value;

[0073] As can be seen from the foregoing, the embodiment of the present invention sets a control strategy for the receiving-end converter station. Specifically, one of the receiving-end converter stations adopts a constant DC voltage control method, and the other receiving-end converter stations adopt a constant power control method. When an AC fault occurs, the receiving-end converter stations using different control methods also need to take different countermeasures.

[0074] Furthermore, for the AC fault condition of the receiving-end constant voltage station, the power surplus can be evaluated based on the AC voltage effective value drop, and the calculated surplus power value can be input into the AC energy consumption device at the sending end, so that the AC energy consumption device can absorb the surplus power of the island power grid according to the surplus power value.

[0075] For the AC fault condition of the receiving-end fixed power station, on the basis of inputting the surplus power value into the sending-end AC energy consumption device, the power reference value of the receiving-end converter station is reduced according to the drop of the effective value of the AC voltage.

[0076] In combination with the above, the AC energy consumption device may include multiple groups of AC energy consumption sub-modules, wherein each AC energy consumption sub-module may correspond to an AC energy consumption capacity. Further, based on the AC voltage fault signal and the surplus power value, the AC energy consumption device may be used to absorb the surplus power of the island power grid. Specifically, the following steps may be performed:

[0077] Based on the AC voltage fault signal U low The number of AC energy consumption submodules put into use is calculated based on the AC energy consumption capacity and the surplus power value. When the corresponding number of AC energy consumption submodules are put into use to absorb the surplus power of the island power grid, the number of put-in groups is rounded up. Specifically:

[0078] Wherein, N is the number of AC energy consumption device groups put into use, which represents the number of AC energy consumption submodule groups actually put into use, π represents rounding up, and P 每组交流耗能装置容量Indicates the AC energy consumption capacity corresponding to each group of AC energy consumption sub-modules.

[0079] When using an AC energy consuming device for power dissipation and absorption, the AC energy consuming device itself will also generate energy consumption power. When the actual total energy consumption of the AC energy consuming device is greater than the surplus power that needs to be absorbed, in order to avoid unnecessary power loss of the system, a group of AC energy consuming sub-modules with flexible switching functions can be provided. The AC energy consuming sub-modules can maintain the actual total energy consumption of the AC energy consuming device and the actual fault surplus power within a ±10% difference range through a flexible switching method.

[0080] Specifically, during the surplus power absorption process, the actual total energy consumption power of the AC energy consumption device can be obtained. If the actual total energy consumption power is greater than the surplus power, a group of AC energy consumption sub-modules is selected from multiple groups of AC energy consumption sub-modules through the AC energy consumption device as a flexible switching energy consumption sub-module, wherein the flexible switching energy consumption sub-module is used to control the actual total energy consumption power and the actual fault surplus power to maintain a difference range of ±10%.

[0081] Furthermore, the flexible switching mode for controlling the actual total energy consumption power and the actual fault surplus power to be maintained within a ±10% difference range may specifically be:

[0082] During the surplus power absorption process, if the actual total energy consumption power is greater than the surplus power and the actual total energy consumption power reaches 110% of the surplus power, the flexible switching energy consumption submodule is controlled by the AC energy consumption device to cut off the flexible switching energy consumption submodule, that is, the flexible switching energy consumption submodule is not put into use for power absorption;

[0083] If the actual total energy consumption power is less than the surplus power, and the actual total energy consumption power reaches 90% of the surplus power, the flexible switching energy consumption submodule is put into use again through the control of the AC energy consumption device.

[0084] Therefore, by setting the flexible switching mode of the AC energy consumption device, the surplus power absorption can be adjusted in real time, so that the actual total energy consumption power of the AC energy consumption device and the actual fault surplus power can be maintained within an allowable difference range, avoiding unnecessary power loss of the system.

[0085] Step 204: If the faulty receiving converter station is a receiving fixed power station, the power reference value of the faulty receiving converter station is adjusted according to the surplus power value by the faulty receiving converter station, and the surplus power of the island power grid is absorbed by the AC energy consumption device.

[0086] When the faulty receiving-end converter station is a receiving-end fixed-power station, the faulty receiving-end converter station may adjust the power reference value of the faulty receiving-end converter station according to the surplus power value. Specifically, the power reference value may be controlled to be equal to the active power before the fault minus the surplus power value f according to the power surplus assessment result. At the same time, referring to the relevant process in step 203, the surplus power of the island power grid may be absorbed by the AC energy consumption device.

[0087] Furthermore, when the fault receiving-end converter station detects that the AC voltage has recovered to a preset value, a fault recovery signal can be generated and transmitted to the AC energy consumption device. After receiving the fault recovery signal, the AC energy consumption device can sequentially cut off the energy consumption groups according to the cutting-off rate. At the same time, if the fault receiving-end converter station is a receiving-end fixed power station, its power reference value must be increased according to the increasing slope until it reaches the power before the fault.

[0088] Specifically, if it is detected that the AC voltage of the fault receiving-end converter station has recovered to a preset AC voltage threshold, a fault recovery signal is generated by the fault receiving-end converter station and sent to the AC energy consumption device; then, according to the fault recovery signal, the AC energy consumption device controls the AC energy consumption sub-modules to be cut off in an orderly manner according to the cut-off rate; if the fault receiving-end converter station is a receiving-end fixed power station, the power reference value of the fault receiving-end converter station must also be increased to the pre-fault power according to the increase rate.

[0089] In practical applications, in order to improve the dynamic performance of fault recovery and reduce the degree of system power imbalance, the removal rate of the AC energy consumption device should be basically the same as the power increase rate of the receiving-end fixed power station.

[0090] During the removal process, the following formula can be used to calculate the removal time interval of the AC energy consuming device:

[0091] Wherein, T is the time interval for the AC energy consumption device to cut off a group of AC energy consumption submodules, and L is the power boosting rate of the receiving converter station after fault recovery.

[0092] Then, the AC energy consumption device can control the removal rate to be the same as the lifting rate according to the removal time interval, or control the error between the removal rate and the lifting rate to be within a preset error rate range, wherein the preset error rate range can be independently set according to actual needs, as long as the rates of the two are kept basically consistent during the removal process of the energy consumption device.

[0093] Furthermore, to ensure that the start time of the receiving-end fixed power station is consistent with the start time of the AC energy consumption device switching on and off, after the receiving-end AC fault is restored, the fault receiving-end converter station needs to consider the AC energy consumption communication delay t, so as to start increasing power / cutting off the energy consumption group synchronously with the AC energy consumption device that receives the fault recovery signal after the delay t.

[0094] The communication delay t is determined by the optical fiber communication distance between the sending end and the receiving end. For a certain project, this value is a constant.

[0095] Specifically, if the faulty receiving-end converter station is a receiving-end fixed-power station, the faulty receiving-end converter station is controlled to perform a power boost action after a preset communication delay to synchronize with the energy removal action of the AC energy consumption device.

[0096] Therefore, after the AC fault is restored, by coordinating and controlling the orderly removal speed of the AC energy consumption device and the power recovery speed of the receiving-end fixed power station, a smooth switching from fault to stable operation of the receiving-end converter station is achieved, and the receiving-end AC fault ride-through control is realized.

[0097] In an embodiment of the present invention, a receiving-end AC fault ride-through control method suitable for a multi-terminal transmission system of a large-scale renewable energy island at an ultra-long distance is proposed. Aiming at the problem of insufficient coordination between the existing AC energy consumption device and the multi-terminal DC transmission system, the receiving-end AC fault ride-through is achieved through coordinated operation between the AC energy consumption device and the multi-terminal DC transmission system. For the difference in AC faults between the receiving-end controlled voltage and the controlled power converter station, different fault ride-through strategies are proposed, and the receiving-end power recovery speed is adjusted in conjunction with the sending-end AC energy removal speed, thereby solving the problem of large-scale renewable energy islands at an ultra-long distance and the multi-terminal transmission system being prone to AC fault ride-through during the receiving-end AC fault. Problems that are prone to occur, such as system power imbalance, poor coordination ability, and poor recovery characteristics after fault clearing, are further avoided. Overvoltage lockout of converter stations and equipment overvoltage damage accidents are avoided, enabling the multi-terminal DC transmission system to safely and reliably pass through serious faults on the AC side of the receiving converter station. At the same time, to address the problem of discontinuous energy consumption capacity when configuring AC energy-consuming resistors in groups, a flexible switching strategy is provided. The power surplus is determined based on the AC voltage drop during the fault, the number of energy-consuming device groups is calculated, and the energy-consuming groups are flexibly switched on and off repeatedly according to the actual power consumption, solving the problem of mismatch between energy consumption power and system surplus power caused by discontinuous AC energy consumption capacity.

[0098] As an optional embodiment, the receiving-end AC fault ride-through control method provided by the embodiment of the present invention will be briefly described below in combination with the aforementioned embodiment, with the receiving-end converter station as the execution entity. The details of each step can be referred to the relevant description of the aforementioned embodiment.

[0099] The method provided in an embodiment of the present invention is applied to a receiving-end converter station of a multi-terminal transmission system of a new energy island power grid, wherein the multi-terminal transmission system may further include an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each sending-end converter station is connected to at least two receiving-end converter stations. In combination with the AC energy consumption device, the general process of the method may be: first, if an AC fault is detected, an AC voltage fault signal is generated, and a power surplus evaluation is performed to obtain a surplus power value; then, the AC voltage fault signal and the surplus power value are transmitted to the AC energy consumption device, so that the AC energy consumption device absorbs the island voltage surplus power based on the AC voltage fault signal and the surplus power value; at the same time, if a constant power control mode is currently adopted (i.e., the receiving-end converter station where the fault occurs is a receiving-end fixed power station), the power reference value needs to be adjusted according to the surplus power value.

[0100] Furthermore, the following formula can be used to perform power surplus assessment and calculate the surplus power value:

[0101] Where f is the surplus power value, V m_af is the effective value of the AC side voltage after the fault occurs, V m_pre is the effective value of the AC side voltage before the fault occurs, P pre is the active power before the fault occurs.

[0102] Furthermore, if it is detected that the AC voltage has recovered to the preset AC voltage threshold, it means that the fault has been restored. At this time, a fault recovery signal can be generated and sent to the AC energy consumption device, so that the AC energy consumption device can orderly control the cut-off of the AC energy consumption according to the cut-off rate; if it is detected that the AC energy consumption device orderly controls the cut-off of the AC energy consumption according to the cut-off rate, and a constant power control method is currently adopted, the power reference value can be increased to the pre-fault power according to the increase rate.

[0103] Furthermore, after the fault is recovered, the receiving converter station can increase the power reference value to the pre-fault power according to the increase rate based on the delayed action, so as to achieve synchronization with the removal of the AC energy consumption device. Specifically, if it is detected that the AC energy consumption device controls the removal of the put-in-power AC energy in an orderly manner according to the removal rate, and a constant power control method is currently adopted, the power increase action can be performed after the preset communication delay to synchronize with the energy removal action of the AC energy consumption device.

[0104] The embodiment of the present invention takes the receiving-end converter station as the research object and provides a receiving-end AC fault ride-through control method, so that those skilled in the art can have a more intuitive understanding of the relevant processing flow from the occurrence of a fault to the recovery of the fault in the receiving-end converter station.

[0105] As an optional embodiment, the following will combine the above embodiments and use the AC energy consumption device as the execution body to briefly describe the receiving-end AC fault ride-through control method provided by the embodiment of the present invention. The details of each step can be referred to the relevant description of the above embodiments.

[0106] The method provided in an embodiment of the present invention is applied to an AC energy consumption device of a multi-terminal transmission system of a new energy island power grid, wherein the multi-terminal transmission system further includes at least one sending-end converter station connected to the AC energy consumption device, wherein each sending-end converter station is connected to at least two receiving-end converter stations. Then, in combination with the receiving-end converter stations, the general process of this method can be: first, receiving the AC voltage fault signal and surplus power value transmitted by the receiving-end converter station where the AC fault occurs; then, based on the AC voltage fault signal and surplus power value, controlling the input to absorb the surplus power of the island power grid.

[0107] Furthermore, according to the above content, the AC energy consumption device can include multiple groups of AC energy consumption sub-modules, each of which corresponds to an AC energy consumption capacity. Based on the AC voltage fault signal and the surplus power value, the control of absorbing the surplus power of the island power grid can be:

[0108] First, based on the AC voltage fault signal, the number of AC energy consumption submodules to be put into use is calculated using the AC energy consumption capacity and the surplus power value. When the corresponding number of AC energy consumption submodules are put into use to absorb the surplus power of the island grid, the number of put-in groups is rounded up. Specifically:

[0109] Where N is the number of AC energy consumption device groups put into use, which represents the number of AC energy consumption submodule groups actually put into use, π represents rounding up, and P 每组交流耗能装置容量 Indicates the AC energy consumption capacity corresponding to each group of AC energy consumption sub-modules.

[0110] Then, the actual total energy consumption during the surplus power absorption process is obtained. If the actual total energy consumption is greater than the surplus power, one group of AC energy consumption sub-modules is selected from multiple groups of AC energy consumption sub-modules as a flexible switching energy consumption sub-module. The flexible switching energy consumption sub-module is used to control the actual total energy consumption and the actual fault surplus power to maintain a difference range of ±10%.

[0111] Furthermore, the actual total energy consumption power and the actual fault surplus power are controlled to be maintained within a difference range of ±10%, which can be:

[0112] During the surplus power absorption process, if the actual total energy consumption power is greater than the surplus power and the actual total energy consumption power reaches 110% of the surplus power, the flexible switching energy consumption sub-module is controlled to be cut off;

[0113] If the actual total energy consumption power is less than the surplus power, and the actual total energy consumption power reaches 90% of the surplus power, the flexible switching energy consumption sub-module is controlled to be put into use again.

[0114] Furthermore, when the receiving converter station where the AC fault occurred is restored, the AC energy consumption device can respond to the fault recovery signal transmitted after the receiving converter station where the AC fault occurred is restored, and control the removal of the put-in-use AC energy consumption sub-modules in an orderly manner according to the removal rate.

[0115] Furthermore, it can be seen from the foregoing that after the fault is restored, the receiving-end converter station can increase the power reference value to the pre-fault power according to the increase rate based on the delayed action to achieve synchronization with the removal of the AC energy consuming device. Accordingly, during the removal process, the AC energy consuming device can obtain the increase rate when the receiving-end converter station performs power increase after the fault is restored, and calculate the removal time interval using the following formula:

[0116] Wherein, T is the time interval for the AC energy consumption device to cut off a group of AC energy consumption submodules, and L is the power boosting rate of the receiving converter station after fault recovery.

[0117] Then, the AC energy consumption device can control the removal rate to be the same as the increase rate according to the removal time interval, or control the error between the removal rate and the increase rate to be within a preset error rate range.

[0118] In line with the processing flow of the receiving-end converter station, the embodiment of the present invention takes the AC energy consuming device as the research object and provides a receiving-end AC fault ride-through control method, so that those skilled in the art can, based on a clear understanding of the processing flow of the receiving-end converter station, combine the AC energy consuming device to further understand the relevant processing flow from the occurrence of the fault to the fault recovery, thereby having a deeper understanding of the overall solution of the receiving-end AC fault ride-through control.

[0119] For better explanation, referring to FIG3 , there is shown a schematic diagram of the overall process of a receiving-end AC fault ride-through control method provided by an embodiment of the present invention. It should be noted that the embodiment of the present invention only schematically illustrates the overall general process of the receiving-end AC fault ride-through control method. The various execution steps can refer to the relevant content in the aforementioned embodiments and will not be elaborated here. It can be understood that the present invention is not limited to this.

[0120] Step 1) Building a multi-terminal transmission system for the new energy island power grid. The specific architecture diagram of the multi-terminal transmission system can be seen in Figure 1a.

[0121] Step 2) Configure the control strategies for the sending-end and receiving-end converter stations, respectively. The sending-end converter station adopts a dual closed-loop constant AC voltage-frequency control method, one receiving-end converter station adopts a constant DC voltage control method, and the remaining receiving-end converter stations adopt a constant power control method. At the same time, configure AC fault power control for the power-controlled receiving-end converter station, set the power parameters during the fault period and the power recovery curve during the fault recovery period, and set the smooth switching slope. The specific control block diagram of the power-controlled receiving-end converter station can be found in Figure 1b.

[0122] Step 3) Real-time detection of the AC voltage of the receiving converter station, and judging whether an AC fault occurs according to the effective value of the AC voltage. If so, the receiving converter station where the fault occurs is determined as the faulty receiving converter station, and an AC voltage fault signal U is generated. low , and simultaneously perform power surplus evaluation to obtain the power surplus value f;

[0123] Step 4) The fault receiving converter station sends the fault signal U low and transmitting the power surplus value f to the AC energy consumption device at the sending end. If the faulty receiving-end converter station is a receiving-end fixed-power station, execute step 5; if the faulty receiving-end converter station is a receiving-end fixed-voltage station, execute step 6.

[0124] Step 5) The fault receiving converter station controls the power reference value to be equal to the active power before the fault minus the surplus power f according to the power surplus value f, and executes step 6;

[0125] Step 6) The AC energy consumption device receives the fault signal U sent by the fault receiving terminal converter station. low After the power surplus value f is obtained, the surplus power of the island power grid is absorbed. When absorbing the surplus power, the number of AC energy consumption devices put into operation is rounded up. When the actual total energy consumption power of the AC energy consumption devices is greater than the surplus power, in addition, to avoid unnecessary power loss in the system, a group of AC energy consumption sub-modules with flexible switching functions are set up. The AC energy consumption sub-modules use a flexible switching method to maintain the actual total energy consumption power of the AC energy consumption devices and the actual fault surplus power within a difference range of ±10%;

[0126] Step 7) When the fault receiving-end converter station detects that the AC voltage has recovered to a preset value, if the fault receiving-end converter station is a receiving-end constant voltage station, a fault recovery signal is generated and sent to the AC energy consuming device. After receiving the fault recovery signal, the AC energy consuming device sequentially removes the energy consuming groups in operation according to the removal speed. If the fault receiving-end converter station is a receiving-end constant power station, step 8 is executed.

[0127] Step 8) The receiving-end fixed power station increases the power reference value according to the increase slope until it reaches the pre-fault power. Simultaneously, the sending-end AC energy consuming devices sequentially remove energy consuming groups according to the removal speed. The removal rate of the AC energy consuming devices is substantially the same as the power increase rate of the receiving-end fixed power station. After the receiving-end AC fault is restored, the fault receiving-end converter station needs to consider the AC energy consumption communication delay t. After the delay t, it starts increasing power / removing energy consuming groups synchronously with the AC energy consuming devices that receive the fault recovery signal.

[0128] As an optional embodiment, an embodiment of the present invention provides a receiving-end AC fault ride-through control device, which is applied to a receiving-end converter station of a new energy island power grid sending multi-end system, wherein the sending multi-end system further includes an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the device includes:

[0129] a first power surplus evaluation module, configured to generate an AC voltage fault signal if an AC fault is detected, and simultaneously perform a power surplus evaluation to obtain a surplus power value;

[0130] a first surplus power value transmission module, configured to transmit the AC voltage fault signal and the surplus power value to the AC energy consuming device, so that the AC energy consuming device absorbs the island voltage surplus power based on the AC voltage fault signal and the surplus power value;

[0131] The power reference value adjustment module is configured to adjust the power reference value according to the surplus power value if a constant power control mode is currently adopted.

[0132] In an optional embodiment, the power surplus first evaluation module is specifically configured to:

[0133] The surplus power value is calculated using the following formula:

[0134] Where f is the surplus power value, V m_af is the effective value of the AC side voltage after the fault occurs, V m_pre is the effective value of the AC side voltage before the fault occurs, P pre is the active power before the fault occurs.

[0135] In an optional embodiment, the device further includes:

[0136] a fault recovery signal generating and sending module, configured to generate a fault recovery signal upon detecting that the AC voltage has recovered to a preset AC voltage threshold, and send the fault recovery signal to the AC energy consuming device, so that the AC energy consuming device can sequentially control the removal of the input AC energy according to the removal rate;

[0137] The power synchronous boosting module is used to increase the power reference value to the pre-fault power according to the boosting rate if it is detected that the AC energy consumption device controls the AC energy consumption to be cut off in an orderly manner according to the cut-off rate, and the constant power control mode is currently adopted.

[0138] In an optional embodiment, the power synchronous boosting module is specifically configured to:

[0139] If it is detected that the AC energy consumption device cuts off the AC energy in an orderly manner according to the cutting rate and the constant power control mode is currently adopted, the power boost action is performed after the preset communication delay to synchronize with the energy cutting action of the AC energy consumption device.

[0140] As an optional embodiment, an embodiment of the present invention further provides a receiving-end AC fault ride-through control device, which is applied to an AC energy consumption device of a new energy island power grid sending multi-terminal system, wherein the sending multi-terminal system further includes at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the device includes:

[0141] A surplus power value receiving module is used to receive an AC voltage fault signal and a surplus power value transmitted by a receiving-end converter station where an AC fault occurs;

[0142] The surplus power input module is used to control the input and absorption of the surplus power of the island power grid based on the AC voltage fault signal and the surplus power value.

[0143] In an optional embodiment, the AC energy consumption device includes a plurality of AC energy consumption submodules, each of the AC energy consumption submodules corresponds to an AC energy consumption capacity, and the surplus power input module includes:

[0144] an AC energy consumption group number calculation module, configured to calculate the number of AC energy consumption submodules to be put into use based on the AC voltage fault signal, the AC energy consumption capacity, and the surplus power value, and to round up the number of put-in groups when putting a corresponding number of AC energy consumption submodules into use to absorb the surplus power of the island power grid;

[0145] The flexible switching setting submodule is used to obtain the actual total energy consumption power during the surplus power absorption process. If the actual total energy consumption power is greater than the surplus power, a group of AC energy consumption submodules is selected from the multiple groups of AC energy consumption submodules as the flexible switching energy consumption submodule. The flexible switching energy consumption submodule is used to control the actual total energy consumption power and the actual fault surplus power to maintain a difference range of ±10%.

[0146] In an optional embodiment, the flexible switching setting submodule includes:

[0147] a flexible switching removal submodule, configured to control the removal of the flexible switching energy consumption submodule if, during the surplus power absorption process, the actual total energy consumption power is greater than the surplus power and the actual total energy consumption power reaches 110% of the surplus power;

[0148] The flexible switching submodule is used to control the flexible switching submodule to be put into use again if the actual total energy consumption power is less than the surplus power and the actual total energy consumption power reaches 90% of the surplus power.

[0149] In an optional embodiment, the device further includes:

[0150] The energy consumption removal submodule is used to control the removal of the AC energy consumption submodules in an orderly manner according to the removal rate in response to receiving a fault recovery signal transmitted after the fault of the receiving end converter station where the AC fault occurs is recovered.

[0151] In an optional embodiment, the device further includes:

[0152] The removal time interval calculation submodule is used to obtain the power boost rate of the receiving converter station after fault recovery during the removal process, and calculate the removal time interval using the following formula:

[0153] Where T is the time interval for the AC energy consumption device to cut off a group of AC energy consumption submodules, f is the surplus power value, L is the power increase rate of the receiving converter station after fault recovery, N 交流耗能装置投入组数 Indicates the number of AC energy consumption submodule groups actually put into use in the AC energy consumption device;

[0154] The cutting rate and promotion rate synchronization submodule is used to control the cutting rate to be the same as the promotion rate according to the cutting time interval, or to control the error between the cutting rate and the promotion rate to be within a preset error rate range.

[0155] 4 shows a block diagram of a receiving-end AC fault ride-through control device according to an embodiment of the present invention, which is applied to a multi-terminal transmission system of a new energy island power grid. The multi-terminal transmission system includes at least an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each sending-end converter station is connected to at least two receiving-end converter stations. The device may specifically include:

[0156] a second power surplus evaluation module 401 configured to determine a receiving-end converter station where an AC fault is detected as a faulty receiving-end converter station, generate an AC voltage fault signal through the faulty receiving-end converter station, and simultaneously perform power surplus evaluation to obtain a surplus power value;

[0157] A second surplus power value transmission module 402 is configured to transmit the AC voltage fault signal and the surplus power value to the AC energy consuming device via the fault receiving-end converter station;

[0158] The receiving-end constant voltage station control processing module 403 is configured to, if the faulty receiving-end converter station is a receiving-end constant voltage station, absorb the surplus power of the island power grid through the AC energy consumption device based on the AC voltage fault signal and the surplus power value;

[0159] The receiving-end fixed power station control processing module 404 is used to adjust the power reference value of the faulty receiving-end converter station according to the surplus power value through the faulty receiving-end converter station if the faulty receiving-end converter station is a receiving-end fixed power station, and to absorb the surplus power of the island power grid through the AC energy consumption device.

[0160] In an optional embodiment, the power surplus evaluation module 401 is specifically configured to:

[0161] The surplus power value corresponding to the fault receiving-end converter station is calculated using the following formula:

[0162] Where f is the surplus power value, V m_af is the effective value of the AC side voltage after the fault occurs, V m_pre is the effective value of the AC side voltage before the fault occurs, P pre is the active power before the fault occurs.

[0163] In an optional embodiment, the AC energy consumption device includes multiple groups of AC energy consumption submodules, each of which corresponds to an AC energy consumption capacity. The receiving-end constant voltage station control processing module 403 includes:

[0164] a module for rounding up the number of AC energy consuming submodules to be put into use, based on the AC voltage fault signal, using the AC energy consumption capacity and the surplus power value, and rounding up the number of AC energy consuming submodules to be put into use when putting a corresponding number of AC energy consuming submodules into use to absorb the surplus power of the island power grid;

[0165] The flexible switching setting module is used to obtain the actual total energy consumption power of the AC energy consumption device during the surplus power absorption process. If the actual total energy consumption power is greater than the surplus power, a group of AC energy consumption sub-modules is selected from the multiple groups of AC energy consumption sub-modules through the AC energy consumption device as a flexible switching energy consumption sub-module. The flexible switching energy consumption sub-module is used to control the actual total energy consumption power and the actual fault surplus power to be maintained within a difference range of ±10%.

[0166] In an optional embodiment, the flexible switching setting module includes:

[0167] A flexible switching removal module is used to control the removal of the flexible switching energy consumption sub-module through the AC energy consumption device during the surplus power absorption process if the actual total energy consumption power is greater than the surplus power and the actual total energy consumption power reaches 110% of the surplus power;

[0168] The flexible switching module is used to control the flexible switching submodule to be put into use again through the AC energy consumption device if the actual total energy consumption power is less than the surplus power and the actual total energy consumption power reaches 90% of the surplus power.

[0169] In an optional embodiment, the device further includes:

[0170] a fault recovery signal generating module, configured to generate a fault recovery signal through the fault receiving end converter station if it is detected that the AC voltage of the fault receiving end converter station has recovered to a preset AC voltage threshold, and send the fault recovery signal to the AC energy consuming device;

[0171] An energy consumption removal module, configured to sequentially control the removal of the put-into AC energy consumption sub-modules according to the removal rate through the AC energy consumption device according to the fault recovery signal;

[0172] The power boosting module is used to boost the power reference value of the faulty receiving-end converter station to the pre-fault power according to the boosting rate if the faulty receiving-end converter station is a receiving-end fixed-power station.

[0173] In an optional embodiment, the device further includes:

[0174] The removal time interval calculation module is used to calculate the removal time interval of the AC energy consumption device using the following formula during the removal process:

[0175] Wherein, T is the time interval for the AC energy consumption device to cut off a group of AC energy consumption submodules, L is the power increase rate of the receiving converter station after fault recovery, N 交流耗能装置投入组数 Indicates the number of AC energy consumption submodule groups actually put into use in the AC energy consumption device;

[0176] a cutting rate and raising rate synchronization module, configured to control the cutting rate to be the same as the raising rate through the AC energy dissipation device according to the cutting time interval, or to control the error between the cutting rate and the raising rate to be within a preset error rate range;

[0177] The power boost delay execution module is used to control the fault receiving-end converter station to perform a power boost action after a preset communication delay if the fault receiving-end converter station is a receiving-end fixed power station, so as to synchronize with the energy consumption removal action of the AC energy consumption device.

[0178] In an optional embodiment, all sending-end converter stations adopt a dual closed-loop constant AC voltage-frequency control method. For each of the at least two receiving-end converter stations corresponding to the sending-end converter station, one of the receiving-end converter stations adopts a constant DC voltage control method, and the remaining receiving-end converter stations adopt a constant power control method.

[0179] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the aforementioned method embodiment.

[0180] An embodiment of the present invention further provides an electronic device, the device including a processor and a memory:

[0181] The memory is used to store program codes and transmit the program codes to the processor;

[0182] The processor is configured to execute the receiving-end AC fault ride-through control method of any embodiment of the present invention according to instructions in the program code.

[0183] An embodiment of the present invention further provides a computer-readable storage medium, which is used to store program code, and the program code is used to execute the receiving-end AC fault ride-through control method of any embodiment of the present invention.

[0184] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0185] In the several embodiments provided in this 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 merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, 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.

[0186] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0187] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0188] 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 invention, 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 and includes several instructions for enabling 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 invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0189] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. 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 invention.

Claims

1. A receiving-end AC fault ride-through control method, characterized in that: A receiving-end converter station applied to a multi-end sending system of a new energy island power grid, wherein the multi-end sending system further comprises an AC energy consumption device, and at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the method comprises: If an AC fault is detected, an AC voltage fault signal is generated, and a power surplus evaluation is performed to obtain a surplus power value; Transmitting the AC voltage fault signal and the surplus power value to the AC energy consumption device, so that the AC energy consumption device absorbs the island voltage surplus power based on the AC voltage fault signal and the surplus power value; If a constant power control mode is currently adopted, the power reference value needs to be adjusted according to the surplus power value.

2. The receiving-end AC fault ride-through control method according to claim 1, characterized in that: The performing power surplus evaluation to obtain a surplus power value includes: The surplus power value is calculated using the following formula: Where f is the surplus power value, V m_af is the effective value of the AC side voltage after the fault occurs, V m_pre is the effective value of the AC side voltage before the fault occurs, P pre is the active power before the fault occurs.

3. The receiving-end AC fault ride-through control method according to claim 1, characterized in that: Also includes: If it is detected that the AC voltage is restored to the preset AC voltage threshold, a fault recovery signal is generated, and the fault recovery signal is sent to the AC energy consumption device, so that the AC energy consumption device can control the cut-off of the AC energy consumption in an orderly manner according to the cut-off rate; If it is detected that the AC energy consumption device controls the cut-off of the AC energy consumption in an orderly manner according to the cut-off rate, and the constant power control mode is currently adopted, the power reference value is increased to the pre-fault power according to the increase rate.

4. The receiving-end AC fault ride-through control method according to claim 3, characterized in that: If it is detected that the AC energy consumption device controls the AC energy consumption to be cut off in an orderly manner according to the cutting rate, and the constant power control mode is currently adopted, the power reference value is increased to the power before the fault according to the increasing rate, including: If it is detected that the AC energy consumption device controls the cutting of the AC energy consumption in an orderly manner according to the cutting rate, and the constant power control method is currently adopted, the power boost action is performed after the preset communication delay to synchronize with the energy cutting action of the AC energy consumption device.

5. A receiving-end AC fault ride-through control method, characterized in that: An AC energy consumption device applied to a multi-terminal transmission system of a new energy island power grid, wherein the multi-terminal transmission system further comprises at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the method comprises: receiving an AC voltage fault signal and a surplus power value transmitted by a receiving-end converter station where an AC fault occurs; Based on the AC voltage fault signal and the surplus power value, control is performed to absorb the surplus power of the island power grid.

6. The receiving-end AC fault ride-through control method according to claim 5, characterized in that: The AC energy consumption device includes a plurality of groups of AC energy consumption submodules, each of which corresponds to an AC energy consumption capacity. Based on the AC voltage fault signal and the surplus power value, the control of absorbing the surplus power of the island power grid includes: Based on the AC voltage fault signal, the number of AC energy consumption submodules put into use is calculated by the AC energy consumption capacity and the surplus power value, and when the corresponding number of AC energy consumption submodules are put into use to absorb the surplus power of the island power grid, the number of put-in groups is rounded up for use; The actual total energy consumption power during the surplus power absorption process is obtained. If the actual total energy consumption power is greater than the surplus power, a group of AC energy consumption sub-modules is selected from the multiple groups of AC energy consumption sub-modules as a flexible switching energy consumption sub-module, and the flexible switching energy consumption sub-module is used to control the actual total energy consumption power and the actual fault surplus power to maintain a difference range of ±10%.

7. The receiving-end AC fault ride-through control method according to claim 6, characterized in that: The control of the actual total energy consumption power and the actual fault surplus power is maintained within a difference range of ±10%, including: During the surplus power absorption process, if the actual total energy consumption power is greater than the surplus power, and the actual total energy consumption power reaches 110% of the surplus power, the flexible Switching energy-consuming submodules; If the actual total energy consumption power is less than the surplus power, and the actual total energy consumption power reaches 90% of the surplus power, the flexible switching energy consumption sub-module is controlled to be put into use again.

8. The receiving-end AC fault ride-through control method according to claim 6, characterized in that: Also includes: In response to receiving a fault recovery signal transmitted after the receiving-end converter station where the AC fault occurs recovers, the AC energy-consuming submodules put into operation are removed in an orderly controlled manner according to a removal rate.

9. The receiving-end AC fault ride-through control method according to claim 8, characterized in that: Also includes: During the removal process, the power increase rate of the receiving converter station after fault recovery is obtained, and the removal time interval is calculated using the following formula: Where T is the time interval for the AC energy consumption device to cut off a group of AC energy consumption submodules, f is the surplus power value, L is the power increase rate of the receiving end converter station after fault recovery, N 交流耗能装置投入组数 Indicates the number of AC energy consumption submodule groups actually put into use by the AC energy consumption device; According to the cutting time interval, the cutting rate is controlled to be the same as the lifting rate, or the error between the cutting rate and the lifting rate is controlled to be within a preset error rate range.

10. A receiving-end AC fault ride-through control method, characterized in that: A sending multi-terminal system applied to a new energy island power grid, the sending multi-terminal system at least comprising an AC energy consumption device and at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the method comprises: The receiving-end converter station where the AC fault is detected is determined as a faulty receiving-end converter station, and an AC voltage fault signal is generated through the faulty receiving-end converter station, and a power surplus evaluation is performed to obtain a surplus power value; Transmitting the AC voltage fault signal and the surplus power value to the AC energy consumption device through the fault receiving end converter station; If the fault receiving-end converter station is a receiving-end constant voltage station, based on the AC voltage fault signal and the surplus power value, the AC energy consumption device is used to absorb the surplus power of the island power grid; If the faulty receiving-end converter station is a receiving-end fixed-power station, the power reference value of the faulty receiving-end converter station is adjusted according to the surplus power value by the faulty receiving-end converter station, and the surplus power of the island power grid is absorbed by the AC energy consumption device.

11. The receiving-end AC fault ride-through control method according to claim 10, characterized in that: The performing power surplus evaluation to obtain a surplus power value includes: The surplus power value corresponding to the fault receiving-end converter station is calculated using the following formula: Where f is the surplus power value, V m_af is the effective value of the AC side voltage after the fault occurs, V m_pre is the effective value of the AC side voltage before the fault occurs, P pre is the active power before the fault occurs.

12. The receiving-end AC fault ride-through control method according to claim 11, characterized in that: The AC energy consumption device includes a plurality of groups of AC energy consumption submodules, each of which corresponds to an AC energy consumption capacity. Based on the AC voltage fault signal and the surplus power value, the AC energy consumption device is used to absorb the surplus power of the island power grid, including: Based on the AC voltage fault signal, the number of AC energy consumption submodules put into use is calculated by the AC energy consumption capacity and the surplus power value, and when the corresponding number of AC energy consumption submodules are put into use to absorb the surplus power of the island power grid, the number of put-in groups is rounded up for use; During the surplus power absorption process, the actual total energy consumption power of the AC energy consumption device is obtained. If the actual total energy consumption power is greater than the surplus power, a group of AC energy consumption sub-modules is selected from the multiple groups of AC energy consumption sub-modules by the AC energy consumption device as a flexible switching energy consumption sub-module. The flexible switching energy consumption sub-module is used to control the actual total energy consumption power and the actual fault surplus power to be maintained within a difference range of ±10%.

13. The receiving-end AC fault ride-through control method according to claim 12, characterized in that: The control of the actual total energy consumption power and the actual fault surplus power is maintained within a difference range of ±10%, including: During the surplus power absorption process, if the actual total energy consumption power is greater than the surplus power, and the actual total energy consumption power reaches 110% of the surplus power, the flexible switching energy consumption submodule is controlled to be removed through the AC energy consumption device; If the actual total power consumption is less than the surplus power, and the actual total power consumption reaches When the surplus power reaches 90%, the flexible switching energy consumption submodule is put into use again through the control of the AC energy consumption device.

14. The receiving-end AC fault ride-through control method according to claim 12, characterized in that: Also includes: If it is detected that the AC voltage of the fault receiving-end converter station is restored to a preset AC voltage threshold, a fault recovery signal is generated through the fault receiving-end converter station, and the fault recovery signal is sent to the AC energy consumption device; According to the fault recovery signal, the AC energy consumption device controls the AC energy consumption submodule to be removed in an orderly manner according to the removal rate; If the faulty receiving-end converter station is a receiving-end fixed-power station, it is also necessary to increase the power reference value of the faulty receiving-end converter station to the pre-fault power according to the increase rate.

15. The receiving-end AC fault ride-through control method according to claim 14, characterized in that: Also includes: During the removal process, the removal time interval of the AC energy consumption device is calculated using the following formula: Wherein, T is the time interval for the AC energy consumption device to cut off a group of AC energy consumption submodules, L is the power increase rate of the receiving end converter station after fault recovery, N 交流耗能装置投入组数 Indicates the number of AC energy consumption submodule groups actually put into use by the AC energy consumption device; According to the removal time interval, the removal rate is controlled to be the same as the lifting rate through the AC energy consumption device, or the error between the removal rate and the lifting rate is controlled to be within a preset error rate range; If the faulty receiving-end converter station is a receiving-end fixed-power station, the faulty receiving-end converter station is controlled to perform a power boost action after a preset communication delay, so as to be synchronized with the energy removal action of the AC energy consumption device.

16. The receiving-end AC fault ride-through control method according to any one of claims 1 to 15, characterized in that: All sending-end converter stations adopt a double closed-loop constant AC voltage-frequency control method. For at least two receiving-end converter stations corresponding to each of the sending-end converter stations, one of the receiving-end converter stations adopts a constant DC voltage control method, and the remaining receiving-end converter stations adopt a constant power control method.

17. A receiving-end AC fault ride-through control device, characterized in that: A receiving-end converter station applied to a multi-end sending system of a new energy island power grid, wherein the multi-end sending system further comprises an AC energy consumption device, and at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the device comprises: A first power surplus evaluation module is used to generate an AC voltage fault signal if an AC fault is detected, and simultaneously perform a power surplus evaluation to obtain a surplus power value; A first surplus power value transmission module, used for transmitting the AC voltage fault signal and the surplus power value to the AC energy consumption device, so that the AC energy consumption device absorbs the island voltage surplus power based on the AC voltage fault signal and the surplus power value; The power reference value adjustment module is used to adjust the power reference value according to the surplus power value if the fixed power control mode is currently adopted.

18. A receiving-end AC fault ride-through control device, characterized in that: An AC energy consumption device applied to a multi-terminal transmission system of a new energy island power grid, wherein the multi-terminal transmission system further comprises at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the device comprises: A surplus power value receiving module is used to receive an AC voltage fault signal and a surplus power value transmitted by a receiving-end converter station where an AC fault occurs; The surplus power input module is used to control the input and absorption of the surplus power of the island power grid based on the AC voltage fault signal and the surplus power value.

19. A receiving-end AC fault ride-through control device, characterized in that: A sending multi-terminal system applied to a new energy island power grid, the sending multi-terminal system at least comprising an AC energy consumption device, at least one sending-end converter station connected to the AC energy consumption device, wherein each of the sending-end converter stations is connected to at least two receiving-end converter stations, and the device comprises: A second power surplus evaluation module is used to determine the receiving-end converter station where the AC fault is detected as a faulty receiving-end converter station, generate an AC voltage fault signal through the faulty receiving-end converter station, and perform power surplus evaluation to obtain a surplus power value; A second surplus power value transmission module, used for transmitting the AC voltage fault signal and the surplus power value to the AC energy consumption device through the fault receiving end converter station; The receiving-end constant voltage station control processing module is used for, if the fault receiving-end converter station is a receiving-end constant voltage station, to, based on the AC voltage fault signal and the surplus power value, Energy-consuming devices are put into use to absorb the surplus power of the island power grid; The receiving-end fixed power station control processing module is used to adjust the power reference value of the faulty receiving-end converter station according to the surplus power value through the faulty receiving-end converter station if the faulty receiving-end converter station is a receiving-end fixed power station, and to absorb the surplus power of the island power grid through the AC energy consumption device.

20. An electronic 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 receiving-end AC fault ride-through control method described in any one of claims 1-16 according to the instructions in the program code.

21. 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 receiving-end AC fault ride-through control method according to any one of claims 1-16.

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