Direct current fault ride-through sending end alternating current voltage stability control method for new energy sending

Abstract

The application relates to a direct-current fault ride-through sending-end alternating-current voltage stability control method of a new energy sending end. The method comprises the following steps: acquiring direct-current line operation data; in the case that the direct-current line operation data is detected to have abnormal data, sending an instruction to switch the control mode of a fault pole of a sending-end converter from a network-constructing type control mode to a network-following type control mode, and starting a de-ionization process by reducing the direct-current side voltage; the network-following type control mode is an active power and reactive power decoupling control mode; after the de-ionization process is completed, the fault pole of the sending-end converter is controlled to recover from the network-following type control mode to the network-constructing type control mode, and the fault pole of the sending-end converter and a non-fault pole of the sending-end converter are controlled to be put into a capacitor voltage average value control mode; in the case that the capacitor voltage average value control mode exceeds a preset time period, the capacitor voltage reference value change amount is controlled to be zero according to a preset descending rate, and a corresponding target voltage value of a direct-current transmission line is output, so that the stability of the sending-end alternating-current voltage can be improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power safety, in particular to a direct-current fault ride-through sending-end alternating-current voltage stability control method, system and device for new energy sending, computer equipment, a storage medium and a computer program product. BACKGROUND

[0002] With the development of power safety technology, power electronic converter technology appears, and most new energy generators are connected to the power grid through power electronic converters; flexible direct-current power transmission based on voltage source converters is a development trend of long-distance direct-current power transmission; microgrids, distributed power sources and active power filters on the distribution network side also need to use converters. With the increasing proportion of power electronic converters in power systems, the traditional power grid dominated by synchronous generators is changing.

[0003] In the conventional technology, the sending-end converter is a flexible direct current, and is a bipolar connection. In normal operation, the sending-end converter adopts a network-forming control mode to provide alternating-current voltage for new energy of the sending-end alternating-current system. When the bipolar operation of the direct-current system occurs a direct-current transmission line fault, the reactive power flow of the sending-end alternating-current system and the capacitor voltage of the sending-end converter submodule fluctuate, which may cause instability of the sending-end alternating-current voltage. SUMMARY

[0004] Therefore, it is necessary to provide a direct-current fault ride-through sending-end alternating-current voltage stability control method, system and device for new energy sending, computer equipment, a storage medium and a computer program product, which can improve the stability of the sending-end alternating-current voltage.

[0005] In a first aspect, the application provides a direct current fault ride-through sending-end alternating current voltage stability control method for new energy sending. The method comprises: obtaining direct current line operation data corresponding to a direct current transmission line in a power system; the direct current line operation data representing an operation state of the direct current transmission line; in a case where the direct current line operation data detects abnormal data, sending an instruction to switch a control mode of a fault pole of a sending-end converter corresponding to the direct current transmission line from a network configuration type control mode to a network following type control mode, and to reduce a direct current side voltage to start a de-ionization process; the network following type control mode is an active and reactive decoupling control mode; wherein a d-axis active component in the network following type control mode is used to control the fault pole of the sending-end converter to maintain capacitor voltage stability; a q-axis reactive component in the network following type control mode is used to output a q-axis current reference value of a non-fault pole of the sending-end converter in the network configuration type control mode as a target value, and a phase angle θ required by the network following type control mode is given by the non-fault pole of the sending-end converter in the network configuration type control mode; after the de-ionization process ends, the fault pole of the sending-end converter is controlled to recover from the network following type control mode to the network configuration type control mode, and the fault pole of the sending-end converter and the non-fault pole of the sending-end converter are controlled to be put into a capacitor voltage average value control mode; in a case where the capacitor voltage average value control mode exceeds a preset time period, a capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode is controlled to be zero according to a preset descending rate, and a target voltage value of the direct current transmission line is output.

[0006] In a second aspect, the application also provides a DC fault ride-through sending-end AC voltage stability control system for new energy sending. The system comprises a sending-end AC module, a sending-end flexible DC converter station, a DC transmission line, a receiving-end flexible DC converter station and a receiving-end AC module. The sending-end AC module is configured to send new energy power to the sending-end flexible DC converter station. The sending-end AC module has new energy and does not have a conventional power source. The sending-end flexible DC converter station is configured to send the new energy power to the DC transmission line. When the DC line operation data detection detects abnormal data, an instruction is sent to switch the control mode of the sending-end converter fault pole corresponding to the DC transmission line from a network construction type control mode to a network following type control mode, to reduce the start of the DC side voltage ionization process. After the ionization process ends, the sending-end converter fault pole is controlled to recover from the network following type control mode to the network construction type control mode. The DC transmission line is configured to transmit the new energy power from the sending-end flexible DC converter station to the receiving-end flexible DC converter station. The receiving-end flexible DC converter station is configured to accept the new energy power corresponding to the DC transmission line to be sent to the receiving-end AC module. The receiving-end AC module is configured to accept the new energy power corresponding to the receiving-end flexible DC converter station. The receiving-end AC module has a conventional power source.

[0007] In a third aspect, the application further provides a direct-current fault ride-through sending-end alternating-current voltage stability control device for new energy sending. The device comprises: a direct-current line operation data acquisition module, configured to acquire direct-current line operation data corresponding to a direct-current transmission line in a power system; the direct-current line operation data representing an operation state of the direct-current transmission line; a control module switching module, configured to, in the case where the direct-current line operation data detects abnormal data, send an instruction to switch a control mode of a fault pole of a sending-end converter corresponding to the direct-current transmission line from a network-constructing type control mode to a network-following type control mode, and reduce a direct-current side voltage starting de-ionization process; the network-following type control mode being an active and reactive decoupling control mode; wherein a d-axis active component in the network-following type control mode is used to control the fault pole of the sending-end converter to maintain capacitor voltage stability; a q-axis reactive component in the network-following type control mode is used to output a q-axis current reference value of a non-fault pole of the sending-end converter under the network-constructing type control mode as a target value, and a phase angle θ required by the network-following type control mode is given by the non-fault pole of the sending-end converter under the network-constructing type control mode; a control mode recovery module, configured to, after the de-ionization process ends, control the fault pole of the sending-end converter to recover from the network-following type control mode to the network-constructing type control mode, and control the fault pole of the sending-end converter and the non-fault pole of the sending-end converter to be put into a capacitor voltage average value control mode; and a target voltage value obtaining module, configured to, in the case where the capacitor voltage average value control mode exceeds a preset time period, control a capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode to be zero according to a preset descending rate, and output a corresponding target voltage value of the direct-current transmission line.

[0008] In a fourth aspect, the present application also provides a computer device. The computer device comprises a memory and a processor, the memory stores a computer program, and the processor implements the following steps when executing the computer program: obtaining DC line operation data corresponding to a DC transmission line in a power system; the DC line operation data representing an operation state of the DC transmission line; in a case where the DC line operation data detects abnormal data, sending an instruction to switch a control mode of a sending-end converter faulty pole corresponding to the DC transmission line from a network-forming control mode to a network-following control mode, and reducing a DC side voltage to start a de-ionization process; the network-following control mode is an active and reactive decoupling control mode; wherein a d-axis active component in the network-following control mode is used to control the sending-end converter faulty pole to maintain capacitor voltage stability; a q-axis reactive component in the network-following control mode is used to output a q-axis current reference value of a sending-end converter non-faulty pole in the network-forming control mode as a target value, and a phase angle θ required by the network-following control mode is given by the sending-end converter non-faulty pole in the network-forming control mode; after the de-ionization process ends, the sending-end converter faulty pole is controlled to recover from the network-following control mode to the network-forming control mode, and the sending-end converter faulty pole and the sending-end converter non-faulty pole are controlled to be put into a capacitor voltage average value control mode; in a case where the capacitor voltage average value control mode exceeds a preset time period, a capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode is controlled to be zero according to a preset descending rate, and a corresponding target voltage value of the DC transmission line is output.

[0009] In a fifth aspect, the application also provides a computer readable storage medium. The computer readable storage medium has a computer program stored thereon, and the computer program, when executed by a processor, implements the following steps: obtaining DC line operation data corresponding to a DC transmission line in a power system; the DC line operation data representing an operation state of the DC transmission line; in a case where the DC line operation data detects abnormal data, sending an instruction to switch a control mode of a sending-end converter faulty pole corresponding to the DC transmission line from a grid-forming control mode to a grid-following control mode, and reducing a DC side voltage to start a de-ionization process; the grid-following control mode being an active and reactive decoupling control mode; wherein a d-axis active component in the grid-following control mode is used to control the sending-end converter faulty pole to maintain capacitor voltage stability; a q-axis reactive component in the grid-following control mode is used to output a q-axis current reference value of a sending-end converter non-faulty pole in the grid-forming control mode as a target value, and a phase angle θ required by the grid-following control mode is given by the sending-end converter non-faulty pole in the grid-forming control mode; after the de-ionization process ends, controlling the sending-end converter faulty pole to recover from the grid-following control mode to the grid-forming control mode, and controlling the sending-end converter faulty pole and the sending-end converter non-faulty pole to enter a capacitor voltage average value control mode; in a case where the capacitor voltage average value control mode exceeds a preset time period, controlling a capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode to be zero according to a preset descending rate, and outputting a corresponding target voltage value of the DC transmission line.

[0010] In a sixth aspect, the present application also provides a computer program product. The computer program product comprises a computer program which, when executed by a processor, implements the following steps: obtaining DC line operation data corresponding to a DC transmission line in a power system; the DC line operation data representing an operating state of the DC transmission line; in the case where the DC line operation data detects abnormal data, sending an instruction to switch a control mode of a faulty pole of a sending converter corresponding to the DC transmission line from a grid-forming control mode to a grid-following control mode, and reducing a DC side voltage to start a de-ionization process; the grid-following control mode being an active and reactive decoupling control mode; wherein a d-axis active component in the grid-following control mode is used to control the faulty pole of the sending converter to maintain capacitor voltage stability; a q-axis reactive component in the grid-following control mode is used to output a q-axis current reference value of a non-faulty pole of the sending converter in the grid-forming control mode as a target value, and a phase angle θ required by the grid-following control mode is given by the non-faulty pole of the sending converter in the grid-forming control mode; after the de-ionization process ends, controlling the faulty pole of the sending converter to recover from the grid-following control mode to the grid-forming control mode, and controlling the faulty pole of the sending converter and the non-faulty pole of the sending converter to enter a capacitor voltage average value control mode; in the case where the capacitor voltage average value control mode exceeds a preset time period, controlling a capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode to be zero according to a preset descending rate, and outputting a corresponding target voltage value of the DC transmission line.

[0011] The new energy sending DC fault ride-through sending end AC voltage stability control method, system, device, computer equipment, storage medium and computer program product, by obtaining the DC line operation data corresponding to the DC transmission line in the power system; the DC line operation data represents the operation state of the DC transmission line; in the case that the DC line operation data detects abnormal data, an instruction is sent to switch the control mode of the sending end converter fault pole corresponding to the DC transmission line from the grid-forming control mode to the grid-following control mode, and the DC side voltage start de-ionization process is reduced; the grid-following control mode is an active and reactive decoupling control mode; wherein the d-axis active component in the grid-following control mode is used to control the sending end converter fault pole to maintain the capacitor voltage stability; the q-axis reactive component in the grid-following control mode is used to output the q-axis current reference value of the sending end converter non-fault pole in the grid-forming control mode as a target value, and the phase angle θ required by the grid-following control mode is given by the sending end converter non-fault pole in the grid-forming control mode; after the de-ionization process ends, the sending end converter fault pole is controlled to recover from the grid-following control mode to the grid-forming control mode, and the sending end converter fault pole and the sending end converter non-fault pole are put into the capacitor voltage average value control mode; in the case that the capacitor voltage average value control mode exceeds the preset time period, the capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode is controlled to zero according to the preset descending rate, and the corresponding target voltage value of the DC transmission line is output.

[0012] By switching the control mode of the sending end converter fault pole corresponding to the DC transmission line from the grid-forming control mode to the grid-following control mode before the de-ionization process, and keeping using the grid-following control mode during the de-ionization process, and putting the sending end converter fault pole and the sending end converter non-fault pole into the capacitor voltage average value control mode after the de-ionization ends, the fluctuation of the sending end AC system reactive power flow and the sending end converter sub-module capacitor voltage when the DC system bipolar operation occurs DC transmission line fault is solved, and the stability of the sending end AC voltage is improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is an application environment diagram of a new energy sending DC fault ride-through sending end AC voltage stability control method in one embodiment;

[0014] Figure 2 It is a flowchart of a new energy sending DC fault ride-through sending end AC voltage stability control method in one embodiment;

[0015] Figure 3 It is a flowchart of a de-ionization method in one embodiment;

[0016] Figure 4 It is a flowchart of a de-ionization method in another embodiment;

[0017] Figure 5 Flow chart for realizing method of capacitor voltage average value control mode in one embodiment;

[0018] Figure 6 Flow chart for realizing method of target voltage value in one embodiment;

[0019] Figure 7 System structure schematic diagram of a new energy sending out DC fault ride through sending end AC voltage stability control method in one embodiment;

[0020] Figure 8 Circuit structure schematic diagram in one embodiment under network type control mode;

[0021] Figure 9 Circuit structure schematic diagram of capacitor voltage average value control mode in one embodiment;

[0022] Figure 10 Structure block diagram of a new energy sending out DC fault ride through sending end AC voltage stability control device in one embodiment;

[0023] Figure 11 Internal structure diagram of computer equipment in one embodiment. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0025] The new energy sending out DC fault ride through sending end AC voltage stability control method provided by the embodiments of the present application can be applied to, for example, Figure 1The application environment shown. Among them, the terminal 102 communicates with the server 104 through the network. The data storage system can store the data required by the server 104 to process. The data storage system can be integrated on the server 104, or placed on the cloud or other network servers. Obtain the DC line operation data corresponding to the DC transmission line in the power system; the DC line operation data represents the operation state of the DC transmission line; in the case of detecting abnormal data in the DC line operation data, send an instruction to switch the control mode of the sending end converter fault pole corresponding to the DC transmission line from the network construction type control mode to the network following type control mode, and reduce the DC side voltage to start the ionization process; the network following type control mode is an active and reactive decoupling control mode; the d-axis active component in the network following type control mode is used to control the sending end converter fault pole to maintain the capacitor voltage stable; the q-axis reactive component in the network following type control mode is used to output the q-axis current reference value of the sending end converter non-fault pole in the network construction type control mode as the target value, and the phase angle θ required by the network following type control mode is given by the sending end converter non-fault pole in the network construction type control mode; after the ionization process ends, control the sending end converter fault pole to recover from the network following type control mode to the network construction type control mode, and control the sending end converter fault pole and the sending end converter non-fault pole to enter the capacitor voltage average value control mode; in the case where the capacitor voltage average value control mode exceeds the preset time period, control the capacitor voltage reference value change corresponding to the capacitor voltage average value control mode to zero according to the preset descending rate, and output the corresponding target voltage value of the DC transmission line. Among them, the terminal 102 can be, but is not limited to, various personal computers, notebook computers, smart phones, tablet computers, Internet of Things devices and portable wearable devices, Internet of Things devices can be smart speakers, smart televisions, smart air conditioners, smart car devices, etc. Portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The server 104 can be implemented by an independent server or a server cluster composed of multiple servers.

[0026] In one embodiment, as shown in Figure 2 , a new energy sending DC fault ride-through sending end AC voltage stability control method is provided. Taking the server in Figure 1 as an example, the method includes the following steps:

[0027] Step 202, obtaining DC line operation data corresponding to the DC transmission line in the power system.

[0028] Among them, the DC line operation data can be the message generated by the DC transmission line during operation, wherein the DC line operation data represents the operation state of the DC transmission line.

[0029] Specifically, the server obtains the DC line operation data corresponding to the DC transmission line from the terminal in response to an instruction of the terminal, and stores the obtained DC line operation data into a storage unit, and when the server needs to process any data record in the DC line operation data, the data record is called from the storage unit to a volatile storage resource for calculation by the central processor. Wherein, the any data record can be a single data input to the central processor, or multiple data input to the central processor at the same time.

[0030] For example, the server 104 obtains the DC line operation data corresponding to the DC transmission line from the terminal 102 in response to an instruction of the terminal 102, and stores the data into a storage unit in the server 104, wherein the server 104 obtains 10 data records, and multiple data can be input to the central processor at the same time.

[0031] Step 204, when the DC line operation data detects abnormal data, an instruction is sent to switch the control mode of the sending-end converter fault pole corresponding to the DC transmission line from the grid-forming control mode to the grid-following control mode, and to reduce the DC side voltage to start the deionization process.

[0032] Wherein, the sending-end converter fault pole can be the fault pole corresponding to the input-end converter on the DC transmission line, wherein the converter can be a device for AC / DC conversion composed of a single or multiple converter bridges.

[0033] Wherein, the grid-forming control mode can be to control the sending-end converter fault pole using a grid-forming converter control architecture.

[0034] Wherein, the grid-following control mode can be to control the sending-end converter fault pole based on a voltage-oriented current source.

[0035] Specifically, during the server's monitoring of DC line operating data, if abnormal data is detected, the server sends a command to switch the control mode of the faulty pole of the corresponding sending-end converter of the DC transmission line. Depending on business requirements, the switch can proceed from the current mode to the corresponding target mode. Generally, the control mode for the faulty pole of the sending-end converter is switched from a grid-based control mode to a grid-following control mode. When it is confirmed that the control mode for the faulty pole of the corresponding sending-end converter of the DC transmission line is a grid-following control mode, the faulty pole of the sending-end converter is controlled to reduce the DC-side voltage to initiate the deionization process. The grid-following control mode is an active and reactive power decoupling control mode. In this mode, the d-axis active component is used to control the faulty pole of the sending-end converter to maintain capacitor voltage stability. The q-axis reactive component is used as the target value for the q-axis current reference value output by the non-following pole of the sending-end converter in the grid-based control mode. The phase angle θ required for the grid-following control mode is given by the output of the non-following pole of the sending-end converter in the grid-based control mode.

[0036] Furthermore, based on the activation of the network-based control mode (such as...) Figure 8 As shown), Figure 8 V in ref Here, V is the grid-connected DC voltage reference value, PI is the proportional-integral regulator, and U is the grid-connected DC voltage reference value. dcref I is the DC voltage reference value. dc For direct current, V pj_ref For the modulation wave of the upper bridge arm of the converter, V nj_ref This is the modulation waveform for the lower arm of the converter. Deionization is performed on the DC transmission line based on the grid-connected DC voltage reference value. That is, the grid-connected control mode in the DC transmission line affects the input parameters of the faulty pole of the sending-end converter, causing a change in the input of the faulty pole and further removing ionized factors from the DC transmission line. Based on the grid-connected control mode, the rate at which the DC transmission line's current drops from the initial value to zero is determined according to the initial current value of the DC transmission line experiencing an abnormal situation. The rate of decrease cannot be too fast, otherwise it will cause instability in the DC transmission line; conversely, the rate of decrease cannot be too slow, otherwise it will lead to excessively long fault clearing time in the DC main line, further affecting the operation of other parts of the power grid system. The voltage in the DC transmission line is reduced according to a reasonable DC voltage decrease rate until the current value in the DC transmission line becomes zero. In a DC transmission line, the current value becoming zero could mean that the total electromotive force (EMF) in the line is zero, causing the potential energy of positive charges to disappear. However, the rate of decrease in DC voltage may or may not be zero. When the current value in the DC transmission line is detected to be zero, the total EMF remains constant.

[0037] Step 206, after the deionization process ends, the control of the sending end converter faulty pole is recovered from the grid following type control mode to the grid constructing type control mode, and the sending end converter faulty pole and the sending end converter non-faulty pole are put into the capacitor voltage average value control mode.

[0038] Wherein, the sending end converter non-faulty pole is the non-faulty pole of the corresponding input end of the converter on the DC transmission line of the sending end converter non-faulty pole, and the converter can be a device for AC / DC conversion composed of a single or multiple converter bridges.

[0039] Wherein, the capacitor voltage average value control mode can be the average value of the input capacitor voltage of the sending end converter faulty pole or the sending end converter non-faulty pole to control the parameters of the DC transmission line.

[0040] Specifically, if it is determined that the DC line operation data fails to detect data anomalies, or the amount of data anomalies of the DC line operation data is lower than the threshold value, the recovery mode is further executed, that is, the server sends a command to control the control mode of the sending end converter faulty pole to recover from the grid following type control mode to the grid constructing type control mode. During the recovery process, the change of the DC line operation data is mainly detected. If abnormal data reappears during the recovery process, the recovery process is terminated, and the grid following type control mode is restarted.

[0041] During the recovery of the grid following type control mode to the grid constructing type control mode, the server simultaneously sends a command to control the sending end converter faulty pole and the sending end converter non-faulty pole in the DC transmission line to put them into the capacitor voltage average value control mode (as shown in Figure 9 , according to the capacitor voltage average value control mode, to determine Figure 9 in the U cap_ref is the capacitor voltage reference value, U cap_avg is the average value of the capacitor voltage, and PI is the proportional integral regulator. The acquisition of the capacitor voltage control average value is calculated according to the business demand and the past data, for example, the weighted average of the capacitor voltage control values of the sending end converter faulty pole and the sending end converter non-faulty pole in the past month.

[0042] The capacitor voltage reference value and the capacitor voltage average value are input to the proportional integral regulator, that is, the PI regulator, corresponding to the sending end converter faulty pole and the sending end converter non-faulty pole. The given capacitor voltage reference value and the capacitor voltage average value form a control deviation with the capacitor voltage control value through the PI regulator. The proportional and integral deviations are combined linearly to form a control value. The capacitor voltage reference value and the capacitor voltage average value are controlled to obtain the corresponding grid constructing type DC voltage reference value of the DC transmission line.

[0043] According to the determined grid type DC voltage reference value in the capacitor voltage average value control mode, the voltage value in the DC transmission line is adjusted to the grid type DC voltage reference value at a certain rate, wherein during the adjustment process, the adjustment rate is not allowed to be too fast, otherwise it will cause instability of the DC transmission line; at the same time, the adjustment rate cannot be too slow, otherwise it will lead to a long time for the DC main line to eliminate the fault. Adjust under the preset condition until the voltage value of the DC transmission line and the grid type DC voltage reference value are less than the preset error.

[0044] Step 208, in the case that the capacitor voltage average value control mode exceeds the preset time period, the capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode is controlled to zero according to the preset descending rate, and the corresponding target voltage value of the DC transmission line is output.

[0045] Wherein, the preset time period can be the time of putting the sending end converter fault pole and the sending end converter non-fault pole into the capacitor voltage average value control mode.

[0046] Wherein, the capacitor voltage reference value change amount can be the changeable interval of the capacitor voltage reference value corresponding to the capacitor voltage average value control mode.

[0047] Wherein, the target voltage value can be the voltage of the DC transmission line stabilized by the sending end converter fault pole.

[0048] Specifically, given the time interval of setting the sending end converter fault pole and the sending end converter non-fault pole to put into the capacitor voltage average value control mode, if the time interval has been exceeded, according to the specific situation of the DC transmission line, the descending rate of the capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode is set, that is, the rate of the voltage interval contained in the capacitor voltage reference value change amount is limited, and the capacitor voltage reference value change amount is controlled to decrease from the current value to obtain the decreased capacitor voltage reference value change amount. For example, the capacitor voltage reference value change amount decreases from the current value of 10 to the decreased capacitor voltage reference value change amount of 8, and the descending rate of the capacitor voltage reference value change amount is 2, until the output voltage reference value change amount of the DC transmission line is zero, that is, the voltage interval contained in the output voltage reference value change amount gradually decreases at a predetermined rate until the voltage reference value change amount is zero, so that the target stable voltage of the DC transmission line can be obtained.

[0049] The system structure described in the DC fault ride-through 5 sending end AC voltage stability control method of a new energy source is as shown in Figure 10 .

[0050] In the aforementioned method for stabilizing AC voltage at the sending end of a new energy transmission line during a DC fault crossing, the method involves acquiring DC line operation data corresponding to the DC transmission line in the power system; the DC line operation data characterizes the operating status of the DC transmission line; and when abnormal data is detected in the DC line operation data, the method generates...

[0051] The command switches the control mode of the faulty pole of the sending-end converter corresponding to the DC transmission line from grid-based control mode 0 to grid-following control mode, and reduces the DC side voltage to initiate the deionization process. Grid-following control mode is an active and reactive power decoupling control mode. In grid-following control mode, the d-axis active component is used to control the faulty pole of the sending-end converter to maintain capacitor voltage stability. The q-axis reactive component in grid-following control mode is used as the reference value for the output q-axis current of the non-faulty pole of the sending-end converter in grid-based control mode.

[0052] The phase angle θ required for the grid-type control mode is given by the output of the non-faulty pole of the sending-end converter in the grid-type control mode. After the deionization process is completed, the faulty pole of the sending-end converter is controlled to return from the grid-type control mode to the grid-type control mode, and the faulty pole and the non-faulty pole of the sending-end converter are controlled to enter the capacitor voltage averaging control mode. If the capacitor voltage averaging control mode exceeds the preset time period, the change of the capacitor voltage reference value corresponding to the capacitor voltage averaging control mode is controlled to return to zero according to the preset descent rate, and the corresponding target voltage value of the DC transmission line is output.

[0053] 0. Before the deionization process, the control mode of the faulty pole of the sending-end converter corresponding to the DC transmission line is switched from the grid-based control mode to the grid-following control mode, and the grid-following control mode is maintained during the deionization period. After the deionization is completed, the faulty pole and the non-faulty pole of the sending-end converter are switched to the capacitor voltage average value control mode. This solves the problem of the sending-end converter in bipolar operation of the DC system being unable to operate when a DC transmission line fault occurs.

[0054] Fluctuations in the reactive power flow of the AC system and the capacitor voltage of the sending-end converter submodule improve the stability of the sending-end AC 5 voltage.

[0055] In one embodiment, such as Figure 3 As shown, after sending a command to switch the control mode of the faulty pole of the sending-end converter corresponding to the DC transmission line from the grid-type control mode to the grid-following control mode, and reducing the DC-side voltage to start the deionization process, the following steps are also included:

[0056] Step 302: Determine the reference value of the DC voltage corresponding to the DC transmission line based on the grid-type control mode.

[0057] Among them, the grid-connected DC voltage reference value can be the voltage reference value applied under the grid-connected control mode.

[0058] Specifically, based on the start of the grid-following control mode (as shown in Figure 8 , a grid-following DC voltage reference value corresponding to the DC transmission line is determined, such as Figure 8 V ref is the grid-following DC voltage reference value, V is the grid-following DC voltage, PI is a proportional integral regulator, U dcref is the DC voltage reference value, I dc is the DC current, V pj_ref is the upper bridge arm modulation wave of the converter, and V nj_ref is the lower bridge arm modulation wave of the converter.

[0059] Step 304: Deionization processing is performed on the DC transmission line according to the grid-following DC voltage reference value until the current value of the DC transmission line is zero.

[0060] Specifically, deionization processing is performed on the DC transmission line according to the grid-following DC voltage reference value, that is, the grid-following control mode in the DC transmission line affects the input parameters of the sending end converter fault pole, so that the input of the sending end converter fault pole changes, and further removes the factors in the DC transmission line in the ionized state, that is, based on the grid-following control mode, the initial current value of the DC transmission line under abnormal conditions is determined. The rate at which the DC transmission line decreases from the initial current value to zero. The rate of decline cannot be too fast, otherwise it will cause instability of the DC transmission line; at the same time, the rate of decline cannot be too slow, otherwise it will lead to a long time for the DC main line to eliminate the fault, further affecting the work of other parts of the power grid system. According to the reasonable DC voltage drop rate, the voltage value in the DC transmission line is reduced until the current value in the DC transmission line becomes zero. Among them, the current value in the DC transmission line becomes zero, which may be that the total electromotive force in the current DC transmission line is zero, and the potential energy of the positive charge in the DC transmission line disappears, but the drop rate of the DC voltage may be zero or not. When it is detected that the current value in the DC transmission line has become zero, the total electromotive force in the DC transmission line is kept unchanged.

[0061] In this embodiment, by using the control mode of the sending end converter fault pole corresponding to the DC transmission line to switch from the grid-forming control mode to the grid-following control mode, deionization processing is performed on the DC transmission line, which can repair the fault when the DC transmission line fails, and improve the stability of the DC transmission line.

[0062] In one embodiment, as shown in Figure 4 , deionization processing is performed on the DC transmission line according to the grid-following DC voltage reference value until the current value of the DC transmission line is zero, including:

[0063] Step 402: Determine the rate of decrease of the DC voltage reference value based on the current value of the DC transmission line.

[0064] Specifically, based on the grid-following control mode, the rate at which the current of the DC transmission line drops from its initial value to zero is determined according to the initial current value of the DC transmission line experiencing an anomaly. The rate of decrease cannot be too fast, otherwise it will cause instability in the DC transmission line; conversely, the rate of decrease cannot be too slow, otherwise it will lead to excessively long troubleshooting time for the main DC power line, further affecting the operation of other parts of the power grid system.

[0065] Step 404: Based on the DC voltage drop rate, reduce the voltage value of the DC transmission line until the current value of the DC transmission line is zero.

[0066] Specifically, the voltage in the DC transmission line is reduced at a reasonable rate of decrease until the current in the DC transmission line becomes zero. In the DC transmission line, the current may become zero if the total electromotive force (EMF) is zero, causing the potential energy of the positive charges in the DC transmission line to disappear; however, the rate of decrease in the DC voltage may be zero or not. When the current in the DC transmission line is detected to be zero, the total EMF in the DC transmission line is kept constant.

[0067] In this embodiment, by determining the rate of decrease of the DC voltage reference value based on the current value of the DC transmission line, the voltage value of the DC transmission line is then reduced. This makes the repair process of the DC transmission line more accurate and reduces errors.

[0068] In one embodiment, such as Figure 5 As shown, after the step of controlling the average capacitor voltage control mode for the faulty and non-faulty terminals of the sending-end converter, the following steps are also included:

[0069] Step 502: Determine the capacitor voltage reference value and the capacitor voltage average value according to the capacitor voltage average value control mode.

[0070] The capacitor voltage reference value can be the capacitor voltage reference value in the circuit corresponding to the capacitor voltage average value control mode.

[0071] The average capacitor voltage can be the average voltage of the capacitors in the circuit corresponding to the average capacitor voltage control mode.

[0072] Specifically, during the process of reverting from grid-based control mode to network-connected control mode, the server simultaneously sends commands to control both the faulty and non-faulty poles of the sending-end converter in the DC transmission line to enter the capacitor voltage average value control mode (e.g., Figure 9According to the capacitor voltage average control mode, the network type DC voltage reference value is determined as Figure 9 cap_ref is the capacitor voltage reference value, U cap_avg is the capacitor voltage average value, and PI is a proportional integral regulator. The capacitor voltage average value is calculated according to the service demand and past data, for example, a weighted average of the capacitor voltage control values of the fault pole of the sending converter and the non-fault pole of the sending converter in the past month.

[0073] In step 504, the network type DC voltage reference value corresponding to the DC transmission line is determined according to the capacitor voltage reference value and the capacitor voltage average value.

[0074] The network type DC voltage reference value can be

[0075] Specifically, the capacitor voltage reference value and the capacitor voltage average value are input into the proportional integral regulator corresponding to the fault pole of the sending converter and the non-fault pole of the sending converter, that is, the PI regulator. The proportional and integral deviations of the given capacitor voltage reference value and the capacitor voltage average value and the capacitor voltage control value are combined linearly to form the control value, and the capacitor voltage reference value and the capacitor voltage average value are controlled to obtain the network type DC voltage reference value corresponding to the DC transmission line.

[0076] In step 506, the voltage value of the DC transmission line is adjusted according to the network type DC voltage reference value until the voltage value of the DC transmission line is less than the preset error.

[0077] Specifically, according to the network type DC voltage reference value determined in the capacitor voltage average control mode, the voltage value in the DC transmission line is adjusted to the network type DC voltage reference value at a certain rate. During the adjustment, the adjustment rate cannot be too fast, otherwise it will cause instability of the DC transmission line; at the same time, the adjustment rate cannot be too slow, otherwise it will cause the fault removal time of the DC main line to be too long. The adjustment is carried out under the preset conditions until the voltage value of the DC transmission line is less than the preset error.

[0078] In this embodiment, by putting the fault pole of the sending converter and the non-fault pole of the sending converter into the capacitor voltage average control mode, the network type DC voltage reference value corresponding to the DC transmission line is determined, and then the voltage value of the DC transmission line is adjusted according to the network type DC voltage reference value, which can accurately restore the voltage value of the DC transmission line to the network type DC voltage reference value and reduce the error.

[0079] In one embodiment, as Figure 6 ​As shown, according to the preset descending rate, the control capacitor voltage average value control mode corresponding capacitor voltage reference value change amount is zeroed, and the corresponding target voltage value of the DC transmission line is output, including:

[0080] Step 602, according to the preset descending rate, the current capacitor voltage reference value change amount is controlled to be smaller, and the smaller capacitor voltage reference value change amount is obtained.

[0081] Specifically, given the time interval in which the sending end converter fault pole and the sending end converter non-fault pole corresponding to the input capacitor voltage average value control mode needs to be set, if the time interval has been exceeded, according to the specific situation of the DC transmission line, the descending rate of the capacitor voltage average value control mode corresponding capacitor voltage reference value change amount is set, that is, the rate of the voltage interval contained in the capacitor voltage reference value change amount is limited, and the capacitor voltage reference value change amount is controlled to be smaller from the current value, and the smaller capacitor voltage reference value change amount is obtained. For example, the capacitor voltage reference value change amount is 10 from the current value, the smaller capacitor voltage reference value change amount is 8, and the descending rate of the capacitor voltage reference value change amount is 2.

[0082] Step 604, according to the smaller capacitor voltage reference value change amount, the voltage value of the DC transmission line is adjusted, and the adjusted voltage value of the DC transmission line is obtained.

[0083] Among them, the adjusted voltage value can be a new DC transmission line voltage value obtained by adjusting the DC transmission line according to the capacitor voltage reference value change amount.

[0084] Specifically, compared with the original capacitor voltage reference value change amount, the change amount of the voltage value change of the DC transmission line caused by the smaller capacitor voltage reference value change amount will be smaller than before. According to the capacitor voltage reference value change amount adjusted according to the descending rate, the voltage value of the DC transmission line is adjusted, that is, the adjusted capacitor voltage reference value change amount is added or subtracted on the basis of the original voltage value of the DC transmission line, and the adjusted voltage value of the DC transmission line is obtained.

[0085] Step 606, the smaller capacitor voltage reference value change amount is taken as the current capacitor voltage reference value change amount, and the step of controlling the current capacitor voltage reference value change amount to be smaller according to the preset descending rate to obtain the smaller capacitor voltage reference value change amount is returned to be executed until the capacitor voltage average value control mode corresponding capacitor voltage reference value change amount is zeroed, and the corresponding target voltage value of the DC transmission line is output.

[0086] Specifically, the changed amount of the capacitor voltage reference value after being reduced is used as the changed amount of the original capacitor voltage reference value, that is, the changed amount after being reduced is 8 and the original changed amount is 10, 10 is discarded and 8 is filled in, and then the step of "according to the specific situation of the DC transmission line, the falling rate of the changed amount of the capacitor voltage reference value corresponding to the capacitor voltage average value control mode, that is, the rate of reduction of the voltage interval contained in the changed amount of the capacitor voltage reference value is limited, and the changed amount of the capacitor voltage reference value is controlled to reduce from the current value to obtain the changed amount of the capacitor voltage reference value after being reduced" is executed until the changed amount of the capacitor voltage reference value corresponding to the capacitor voltage average value control mode is zero, and the corresponding target voltage value of the DC transmission line is correspondingly output.

[0087] In the embodiment, by using the changed amount of the capacitor voltage reference value corresponding to the capacitor voltage average value control mode to be zero, a stable output voltage value can be obtained spontaneously, the demand for voltage stabilization is met without increasing the cost, the circuit design is simple, and the reliability of the working circuit is increased.

[0088] In one embodiment, as shown in Figure 7 A new energy sending DC fault ride-through sending end alternating current voltage stabilization control system, characterized in that the system comprises a sending end alternating current module, a sending end flexible DC converter station, a DC transmission line, a receiving end flexible DC converter station and a receiving end alternating current module.

[0089] The sending end alternating current module is used to send new energy power to the sending end flexible DC converter station; wherein the sending end alternating current module has new energy and does not have conventional power supply.

[0090] Specifically, one end of the sending end alternating current module is connected to the power grid system, and the other end is connected to the sending end flexible DC converter station, wherein the end connected to the power grid system is responsible for accepting power input from the power grid system, and the sending end alternating current module has new energy and does not have conventional energy, and the end connected to the sending end flexible DC converter station is used for outputting new energy power.

[0091] The sending end flexible DC converter station is used to send new energy power to the DC transmission line; wherein when abnormal data is detected in the DC line operation data, an instruction is sent to switch the control mode of the sending end converter fault pole corresponding to the DC transmission line from the network construction type control mode to the network following type control mode, to start the de-ionization process of the DC side voltage, and after the de-ionization process is completed, the sending end converter fault pole is controlled to recover from the network following type control mode to the network construction type control mode.

[0092] Specifically, the input end of the sending-end flexible DC converter station is connected with the sending-end AC module, and the output end is connected with the DC power transmission line. The sending-end flexible DC converter station receives the new energy power sent by the sending-end AC module. In the case of abnormal data of the DC power transmission line, the control mode of the sending-end converter fault pole corresponding to the DC power transmission line is switched from the grid-forming control mode to the grid-following control mode, and the DC side voltage is reduced to start the deionization process; the grid-following control mode is an active and reactive decoupling control mode; the d-axis active component in the grid-following control mode is used to control the sending-end converter fault pole to maintain the stability of the capacitor voltage; the q-axis reactive component in the grid-following control mode is used to output the q-axis current reference value of the sending-end converter non-fault pole in the grid-forming control mode as a target value, and the phase angle θ required by the grid-following control mode is given by the sending-end converter non-fault pole in the grid-forming control mode; after the deionization process is completed, the sending-end converter fault pole is restored from the grid-following control mode to the grid-forming control mode, and the sending-end converter fault pole and the sending-end converter non-fault pole are put into the capacitor voltage average control mode; in the case that the capacitor voltage average control mode exceeds the preset time period, the capacitor voltage reference value change amount corresponding to the capacitor voltage average control mode is controlled to be zero according to the preset descending rate, and the corresponding target voltage value of the DC power transmission line is output. Finally, the sending-end flexible DC converter station sends the target voltage value to the DC power transmission line through the connection end of the DC power transmission line.

[0093] The DC power transmission line is used to transmit the new energy power from the sending-end flexible DC converter station to the receiving-end flexible DC converter station.

[0094] Specifically, the input end of the DC power transmission line is connected with the sending-end flexible DC converter station, and the output end of the DC power transmission line is connected with the receiving-end flexible DC converter station. The DC power transmission line obtains the new energy power from the input end, and then transmits the new energy power from the sending-end flexible DC converter station to the receiving-end flexible DC converter station in the form of DC power transmission.

[0095] The receiving-end flexible DC converter station is used to receive the new energy power corresponding to the DC power transmission line and send it to the receiving-end AC module.

[0096] Specifically, the input end of the receiving-end flexible DC converter station is connected with the DC power transmission line, and the output end is connected with the receiving-end AC module. The receiving-end flexible DC converter station obtains the new energy power from the input end, and sends the processed new energy power to the receiving-end AC module through the processing of the receiving-end flexible DC converter station.

[0097] The receiving-end AC module is used to receive the new energy power corresponding to the receiving-end flexible DC converter station; wherein the receiving-end AC module has a conventional power supply.

[0098] Specifically, the input end of the receiving end AC module is connected with the output end of the receiving end flexible DC converter station, and the output end of the receiving end AC module is connected with the power grid system. The receiving end AC module receives the new energy power output by the receiving end flexible DC converter station, and outputs to the power grid system through the receiving end AC module, thereby completing the entire power transmission process.

[0099] By switching the control mode of the sending end converter fault pole corresponding to the DC transmission line from the network configuration type control mode to the network following type control mode before the deionization process, and keeping the network following type control mode during the deionization process, and after the deionization ends, the sending end converter fault pole and the sending end converter non-fault pole are put into the capacitor voltage average control mode, the fluctuation of the sending end AC system reactive power flow and the sending end converter sub-module capacitor voltage when the DC system bipolar operation occurs DC transmission line fault is solved, and the stability of the sending end AC voltage is improved.

[0100] It should be understood that, although each step in the flowchart involved in the above embodiments is displayed in sequence according to the direction of the arrow, these steps are not necessarily executed in the order indicated by the arrow.

[0101] Unless otherwise explicitly stated herein, the execution of these steps is not strictly limited in order, and these steps 5 can be executed in other orders. Moreover, at least part of the steps in the flowchart involved in the above embodiments can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least part of other steps or steps or stages in other steps.

[0102] 0Based on the same inventive concept, the embodiments of the present application also provide a new energy sending DC fault ride-through sending end AC voltage stability control device for implementing the above-mentioned new energy sending DC fault ride-through sending end AC voltage stability control method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme described in the above method, so the specific limitations of one or more new energy sending DC fault ride-through sending end AC voltage stability control device embodiments provided below can be referred to the limitations of the new energy sending DC fault ride-through sending end AC voltage stability control method in the above 5, which will not be repeated here.

[0103] The specific limitations of the one or more new energy sending DC fault ride-through sending end AC voltage stability control device embodiments provided below can be referred to the limitations of the new energy sending DC fault ride-through sending end AC voltage stability control method in the above 5, which will not be repeated here.

[0104] In one embodiment, as Figure 10As shown, a new energy sending DC fault ride-through sending end AC voltage stability control device is provided, comprising: a DC line operation data acquisition module 1002, a control module switching module 1004, a control mode recovery module 1006 and a target voltage value obtaining module 1008, wherein: 0 the DC line operation data acquisition module 1002 is used to acquire the DC line operation data corresponding to the DC transmission line in the power system; the DC line operation data represents the operation state of the DC transmission line;

[0105] The control module switching module 1004 is used to send an instruction to switch the control mode of the sending end converter fault pole corresponding to the DC transmission line from the network configuration type control mode to the network following type control mode and to start the de-ionization process of the DC side voltage when the DC line operation data detects abnormal data;

[0106] 5 The network following type control mode is an active and reactive decoupling control mode; wherein the d-axis active component in the network following type control mode is used to control the sending end converter fault pole to maintain the capacitor voltage stability; the q-axis reactive component in the network following type control mode is used to output the q-axis current reference value of the sending end converter non-fault pole in the network configuration type control mode as the target value, and the phase angle θ required by the network following type control mode is given by the sending end converter non-fault pole in the network configuration type control mode;

[0107] The control mode recovery module 1006 is used to control the sending end converter fault pole to recover from the network following type control mode to the network configuration type control mode and to control the sending end converter fault pole and the sending end converter non-fault pole to enter the capacitor voltage average value control mode after the de-ionization process is completed;

[0108] The target voltage value obtaining module 1008 is used to control the capacitor voltage reference value change amount corresponding to the capacitor voltage average value control mode to be zero according to the preset descending rate and to output the corresponding target voltage value of the DC transmission line when the capacitor voltage average value control mode exceeds the preset time period.

[0109] In one embodiment, the control module switching module 1004 is further used to determine the network following type DC voltage reference value corresponding to the DC transmission line in the network following type control mode; the network following type DC voltage reference value has a mapping relationship with the current value of the DC transmission line; and the de-ionization process of the DC transmission line is performed according to the network following type DC voltage reference value until the current value of the DC transmission line is zero.

[0110] In one embodiment, the control module switching module 1004 is further used to determine the network following type DC voltage reference value descending rate according to the current value of the DC transmission line; and the voltage value of the DC transmission line is reduced according to the DC voltage descending rate until the current value of the DC transmission line is zero.

[0111] In one embodiment, the control mode recovery module 1006 is further configured to determine a capacitor voltage reference value and a capacitor voltage average value based on a capacitor voltage average value control mode; determine a DC voltage reference value corresponding to the grid-type DC transmission line based on the capacitor voltage reference value and the capacitor voltage average value; and adjust the voltage value of the DC transmission line based on the grid-type DC voltage reference value until the voltage value of the DC transmission line and the grid-type DC voltage reference value are less than a preset error.

[0112] In one embodiment, the target voltage value obtaining module 1008 is further configured to: control the change in the current capacitor voltage reference value to decrease according to a preset descent rate, thereby obtaining the reduced change in the capacitor voltage reference value; adjust the voltage value of the DC transmission line according to the reduced change in the capacitor voltage reference value, thereby obtaining the adjusted voltage value of the DC transmission line; use the reduced change in the capacitor voltage reference value as the current change in the capacitor voltage reference value, and return to execute the process of controlling the change in the current capacitor voltage reference value to decrease according to a preset descent rate, thereby obtaining the reduced change in the capacitor voltage reference value, until the change in the capacitor voltage reference value corresponding to the capacitor voltage average value control mode returns to zero, and output the corresponding target voltage value of the DC transmission line.

[0113] The various modules in the aforementioned DC fault-crossing AC voltage stabilization control device for new energy transmission can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.

[0114] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 11 As shown, the computer device includes a processor, memory, and network interface connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores server data. The network interface communicates with external terminals via a network connection. When executed by the processor, the computer program implements a method for stabilizing the AC voltage at the sending end of a new energy power transmission line during DC fault ride-through.

[0115] Those skilled in the art will understand that Figure 11The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0116] In an embodiment, a computer device is also provided, including a memory and a processor. The memory stores a computer program. The processor executes the computer program to implement the steps in the above method embodiments.

[0117] In an embodiment, a computer readable storage medium is provided, which stores a computer program. The computer program is executed by a processor to implement the steps in the above method embodiments.

[0118] In an embodiment, a computer program product or computer program is provided, which includes computer instructions stored in a computer readable storage medium. A processor of a computer device reads the computer instructions from the computer readable storage medium. The processor executes the computer instructions to cause the computer device to perform the steps in the above method embodiments.

[0119] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or authorized by all parties.

[0120] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (Read-Only Memory, ROM), magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetoresistive random access memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric memory (Ferroelectric Random Access Memory, FRAM), phase change memory (Phase Change Memory, PCM), graphene memory, etc. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, etc. As an illustration but not limitation, RAM can be in various forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0121] Any combination of the technical features of the above embodiments can be made. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0122] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for stabilizing and controlling the AC voltage at the sending end of a new energy source during DC fault ride-through, characterized in that, The method includes: Acquire DC line operation data corresponding to DC transmission lines in the power system; the DC line operation data characterizes the operating status of the DC transmission lines; If abnormal data is detected in the DC line operation data, a command is sent to switch the control mode of the faulty pole of the sending end converter corresponding to the DC transmission line from the grid-type control mode to the grid-following control mode, and reduce the DC side voltage to start the deionization process. The grid-following control mode is an active and reactive power decoupling control mode; wherein, the d-axis active component in the grid-following control mode is used to control the faulty pole of the sending-end converter to maintain the stability of the capacitor voltage; the q-axis reactive component in the grid-following control mode takes the q-axis current reference value output by the non-following pole of the sending-end converter in the grid-following control mode as the target value, and the phase angle θ required by the grid-following control mode is given by the output of the non-following pole of the sending-end converter in the grid-following control mode; After the deionization process is completed, the faulty pole of the sending-end converter is controlled to return from the grid-following control mode to the grid-forming control mode, and the faulty pole and the non-faulty pole of the sending-end converter are controlled to enter the capacitor voltage average value control mode. If the average capacitor voltage control mode exceeds a preset time period, the change in the capacitor voltage reference value corresponding to the average capacitor voltage control mode is controlled to return to zero according to a preset rate of decrease, and the corresponding target voltage value of the DC transmission line is output.

2. The method according to claim 1, characterized in that, After the step of sending a command to switch the control mode of the faulty pole of the sending-end converter corresponding to the DC transmission line from the grid-type control mode to the grid-following control mode, and reducing the DC-side voltage to start the deionization process, the method further includes: Based on the grid-following control mode, the grid-following DC voltage reference value corresponding to the DC transmission line is determined; the grid-following DC voltage reference value has a mapping relationship with the current value of the DC transmission line; The DC transmission line is deionized according to the grid-type DC voltage reference value until the current value of the DC transmission line is zero.

3. The method according to claim 2, characterized in that, The step of deionizing the DC transmission line according to the grid-connected DC voltage reference value until the current value of the DC transmission line is zero includes: The rate of decrease of the grid-connected DC voltage reference value is determined based on the current value of the DC transmission line. Based on the rate of decrease of the grid-type DC voltage reference value, the voltage value of the DC transmission line is reduced until the current value of the DC transmission line is zero.

4. The method according to claim 1, characterized in that, After the step of controlling the average capacitor voltage control mode of the faulty terminal and the non-faulty terminal of the sending-end converter, the method further includes: Based on the capacitor voltage average value control mode, the capacitor voltage reference value and the capacitor voltage average value are determined; Based on the capacitor voltage reference value and the average capacitor voltage, determine the DC voltage reference value corresponding to the DC transmission line grid type; Based on the grid-type DC voltage reference value, adjust the voltage value of the DC transmission line until the voltage value of the DC transmission line is less than the preset error of the grid-type DC voltage reference value.

5. The method according to claim 1, characterized in that, The step of controlling the change in the capacitor voltage reference value corresponding to the capacitor voltage average value control mode to zero according to a preset decreasing rate, and outputting the corresponding target voltage value of the DC transmission line, includes: Based on the preset rate of decrease, the change in the current capacitor voltage reference value is controlled to be smaller, and the change in the capacitor voltage reference value after the change is reduced is obtained. The voltage value of the DC transmission line is adjusted based on the change in the reference value of the capacitor voltage after the reduction, to obtain the adjusted voltage value of the DC transmission line. The reduced change in the capacitor voltage reference value is used as the current change in the capacitor voltage reference value. The process returns to the previous step of controlling the current change in the capacitor voltage reference value to decrease according to the preset descent rate, obtaining the reduced change in the capacitor voltage reference value, until the change in the capacitor voltage reference value corresponding to the capacitor voltage average value control mode returns to zero, and the corresponding target voltage value of the DC transmission line is output.

6. A DC fault-through AC voltage stabilization control system for new energy power transmission, characterized in that, The system includes: a sending-end AC module, a sending-end flexible DC converter station, a DC transmission line, a receiving-end flexible DC converter station, and a receiving-end AC module; The sending-end AC module is used to transmit new energy power to the sending-end flexible DC converter station; wherein, the sending-end AC module has new energy and does not have conventional power. The sending-end flexible DC converter station is used to transmit the new energy power to the DC transmission line; wherein, when abnormal data is detected in the DC line operation data corresponding to the DC transmission line, a command is sent to switch the control mode of the faulty pole of the sending-end converter corresponding to the DC transmission line from the grid-type control mode to the grid-following control mode, reduce the DC side voltage to start the deionization process, and after the deionization process is completed, control the faulty pole of the sending-end converter to return from the grid-following control mode to the grid-type control mode; The DC transmission line is used to transmit the new energy power from the sending-end flexible DC converter station to the receiving-end flexible DC converter station; The receiving-end flexible DC converter station is used to receive the new energy power corresponding to the DC transmission line and send it to the receiving-end AC module; The receiving-end AC module is used to receive the new energy power corresponding to the receiving-end flexible DC converter station; wherein, the receiving-end AC module has a conventional power supply.

7. A DC fault-crossing AC voltage stabilization control device for new energy transmission, characterized in that, The device includes: A DC line operation data acquisition module is used to acquire DC line operation data corresponding to DC transmission lines in a power system; the DC line operation data characterizes the operation status of the DC transmission line. The control module switching module is used to send a command to switch the control mode of the faulty pole of the sending end converter of the DC transmission line from the grid-type control mode to the grid-following control mode when abnormal data is detected in the DC line operation data, and reduce the DC side voltage to start the deionization process. The grid-following control mode is an active and reactive power decoupling control mode; wherein, the d-axis active component in the grid-following control mode is used to control the faulty pole of the sending-end converter to maintain the stability of the capacitor voltage; the q-axis reactive component in the grid-following control mode takes the q-axis current reference value output by the non-following pole of the sending-end converter in the grid-following control mode as the target value, and the phase angle θ required by the grid-following control mode is given by the output of the non-following pole of the sending-end converter in the grid-following control mode; The control mode recovery module is used to control the faulty pole of the sending-end converter to return from the grid-following control mode to the grid-forming control mode after the deionization process is completed, and to control the faulty pole and the non-faulty pole of the sending-end converter to switch to the capacitor voltage average value control mode. The target voltage value acquisition module is used to control the change in the capacitor voltage reference value corresponding to the capacitor voltage average control mode to zero according to a preset decrease rate when the capacitor voltage average control mode exceeds a preset time period, and output the corresponding target voltage value of the DC transmission line.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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