CN112865038B - Fault protection method for receiving end valve side of extra-high voltage hybrid multi-end direct current transmission system - Google Patents
Fault protection method for receiving end valve side of extra-high voltage hybrid multi-end direct current transmission system Download PDFInfo
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- CN112865038B CN112865038B CN202110137503.3A CN202110137503A CN112865038B CN 112865038 B CN112865038 B CN 112865038B CN 202110137503 A CN202110137503 A CN 202110137503A CN 112865038 B CN112865038 B CN 112865038B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention discloses a fault protection method for a receiving end valve side of an extra-high voltage hybrid multi-end direct current transmission system, which divides the fault types of the valve side into three types by identifying different fault types of the converter transformer valve side of a receiving end MMC converter station and according to whether the fault of the valve side meets two criteria provided by the invention, and then executes corresponding protection strategies according to different fault types, thereby rapidly removing the fault and realizing the restart of a non-fault valve or station. In addition, aiming at the valve side ground fault of the high-end valve bank, the phase selection type unidirectional thyristor bypass branch circuit provided by the invention can effectively inhibit the direct-current line energy from charging the upper bridge arm submodule capacitor, and plays a role in protecting the submodule capacitor.
Description
Technical Field
The invention relates to the technical field of power transmission and distribution, in particular to a fault protection method for a receiving end valve side of an ultra-high voltage hybrid multi-end direct current transmission system.
Background
The High-Voltage Direct Current transmission (LCC-HVDC) based on the power grid commutation Converter type has the advantages of large transmission capacity, long transmission distance, mature technology and the like, but commutation failure risks exist during inversion operation of the LCC-HVDC, and a Direct Current system is caused to be shut down in severe cases. The Modular Multilevel Converter (MMC) adopting the fully-controlled power electronic device does not have the problem of commutation failure, and has the advantages of active and reactive decoupling control, low harmonic level, filter equipment investment reduction and the like. However, compared with LCC-HVDC with the same voltage and capacity class, the MMC-HVDC has the defects of high construction cost and large operation loss. Therefore, the multi-terminal hybrid direct-current transmission system with the transmitting terminal adopting the LCC and the receiving terminal adopting the MMC can combine the advantages of the transmitting terminal and the receiving terminal, and is one of the important development directions of future high-voltage direct-current transmission.
On the other hand, the hybrid dc transmission system based on the LCC-MMC form is developing towards the direction of high voltage class, in order to meet the demand of high voltage, two valve banks are generally required to be connected in series at each pole on the dc side to boost the dc voltage, wherein the valve bank near the dc polar line is called high-end valve bank, the valve bank near the ground polar line is called low-end valve bank, and meanwhile, because the full-bridge sub-module (FBMMC) can pass through the characteristic of fault, the structure of the flexible dc converter valve based on the semi-Full Hybrid (FHMMC) has also been widely applied.
For a direct current transmission system, generally speaking, when a fault occurs, the closer the distance between a fault point and a valve group is, the greater the influence on the fault point is, and thus, a relatively serious fault which damages a converter valve is mainly located inside a converter station. Different from the network side fault of the converter transformer, when the valve side fault of the converter transformer occurs, because the valve side alternating current bus is directly connected with the converter without isolating the converter transformer, the damage to the valve group is more serious than the network side fault, and the permanent fault of the valve side fault of the converter transformer is mostly a permanent fault. In summary, when the converter transformer valve side has a ground fault, the protection system should quickly complete fault identification and lock the valve bank to complete fault isolation.
At present, the research on the valve side fault of the direct current transmission system mainly aims at the direct current transmission systems with the same types of converter stations at two ends and at a transmitting end and a receiving end, and corresponding research on an extra-high voltage direct current transmission system with a multi-end hybrid structure and a high-low valve group structure is lacked. Therefore, in order to meet the requirements in practical engineering, how to effectively identify and remove different types of valve side faults of a receiving end MMC converter station in an LCC-FHMMC multi-end hybrid extra-high voltage direct current transmission system is an important problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a fault protection method for a receiving end valve side of an extra-high voltage hybrid multi-end direct current transmission system, which can identify different fault types of the converter transformer valve side of an MMC converter station at the receiving end, and then execute corresponding protection outlets according to the different fault types, so that the faults can be quickly removed and key equipment in the station can be protected.
The purpose of the invention is realized by the following technical scheme:
a fault protection method for a receiving end valve side of an extra-high voltage hybrid multi-end direct current transmission system comprises the following steps:
when a converter transformer valve side of a receiving-end MMC station fails, whether the converter transformer valve side of the receiving-end MMC station fails or not and whether the valve side failure is a two-phase interphase failure or not are respectively detected through two preset first judgment data and second judgment data;
determining the fault type by combining the detection result, executing corresponding protection strategies according to different fault types, and sending fault signals of corresponding types to a remote non-fault station;
and after the remote non-fault station receives the fault signals of the corresponding types from the fault station, executing corresponding control logic according to the types of the remote station and the fault signals, and finishing the removal and restart of the fault.
According to the technical scheme provided by the invention, different fault types of the converter transformer valve side of the receiving-end MMC converter station are identified, the fault types of the valve side are divided into three types according to whether the fault of the valve side meets the two criteria provided by the invention, and then corresponding protection outlets are executed according to different fault types, so that the fault is quickly removed and the restarting of a non-fault valve or station is realized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a flowchart of a fault protection method for a receiving end valve side of an ultra-high voltage hybrid multi-end direct current transmission system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an extra-high voltage three-terminal hybrid direct-current power transmission system provided by an embodiment of the invention;
FIG. 3 is a schematic diagram of a topology of an extra-high voltage semi-Fully Hybrid (FHMMC) MMC converter station according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of three types of valve-side fault discrimination logic provided in an embodiment of the present invention;
fig. 5 is a schematic diagram of a first type of fault protection policy provided in an embodiment of the present invention;
fig. 6 is a schematic diagram of a second type of fault protection policy according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a third type of fault protection policy according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a fault protection method for a receiving end valve side of an extra-high voltage hybrid multi-end direct-current transmission system, which is suitable for the extra-high voltage direct-current transmission system with large high-voltage grade transmission capacity, in particular to an extra-high voltage multi-end hybrid direct-current transmission system with a transmitting end adopting LCC (low control circuit) and a receiving end adopting half-full hybrid MMC (FHMMC), and when different types of valve side faults occur on the converter transformer valve side of a receiving end MMC station. As shown in fig. 1, it mainly includes:
In the embodiment of the present invention, the first criterion is expressed as:
|I vcn_x -I vtn_x |＞I set ＝k*I VPEAK_NOM
wherein, I vcn_x 、I vtn_x Measuring points for casing current of an alternating current bus valve side and a converter transformer valve side in the station respectively, wherein n = a, b, c, x = h represents a high-end valve group measuring point, x = l represents a low-end valve group measuring point, k is a proportionality coefficient, a value smaller than 1 is required by combining different engineering examples, in the embodiment of the invention, 0.3 is taken as I VPEAK_NOM Showing the peak value of the ac phase current in the steady state.
The second criterion is expressed as:
U ta_x ＝U tb_x ≠0or U ta_x ＝U tc_x ≠0or U tb_x ＝U tc_x ≠0
wherein, U tn_x Phase voltages of three-phase alternating-current buses at the valve side of the converter transformer are shown, n = a, b, c, x = h shows a valve measuring point of a high-end valve group, x = l shows a measuring point of a low-end valve group, and or shows a logical OR relationship of three discriminants.
As will be understood by those skilled in the art, a, b, c are three-phase labels.
And 2, determining the fault type by combining the detection result, executing a corresponding protection strategy according to different fault types, and sending fault signals of corresponding types to the remote non-fault station.
In the embodiment of the present invention, the faults are divided into three types according to the detection result, which are mainly described as follows:
1) If the high-end valve group judging logic meets the condition that the first criterion does not meet the second criterion, judging that the valve side of the converter transformer of the high-end valve group has an earth fault, and defining the fault as a first type of fault;
2) If the low-end valve group judging logic meets the condition that the first criterion does not meet the second criterion, judging that the valve side of the low-end valve group converter transformer has an earth fault, and defining the low-end valve group converter transformer as a second type of fault;
3) And if the high-end valve bank or low-end valve bank judging logic simultaneously meets the first and second judging data, judging that two-phase interphase faults occur at the converter transformer valve side of the high-end valve bank or low-end valve bank, and defining the faults as a third type of faults.
As can be understood by those skilled in the art, two valve banks are connected in series in the extra-high voltage MMC converter station, the valve bank close to the DC polar line is called a high-end valve bank, and the valve bank close to the grounding polar line is called a low-end valve bank, so that the two valve banks are distinguished.
In the embodiment of the present invention, different protection strategies are respectively adopted for the three types of faults, which are mainly described as follows:
1) If the fault type is the first type of fault, namely the high-end valve group converter transformer valve side has an earth fault, the high-end and low-end valve groups of the fault pole of the fault station are locked, and the fault is trippedAnd defining the phase meeting the criterion condition as a fault phase according to a first criterion, triggering the bypass branch of the unidirectional thyristor of the fault phase to be conducted, and detecting that the current on the direct current side is less than a preset value I dc_set And continues for a preset time t dc_set And then disconnecting the DC pole HSS switch of the fault pole, wherein the preset value I is taken in combination with the disconnection capability of a mechanical switch adopted in actual engineering dc_set Is 15A, preset time t dc_set Is 15ms.
In the embodiment of the invention, the phase selection type unidirectional thyristor bypass branch is a bypass branch formed by connecting thyristors in series and connected with a three-phase upper bridge arm of a high-end valve group of a receiving-end MMC convertor station in parallel, and the topology is as shown in FIG. 3.
2) If the fault type is the second type of fault, namely the low-end valve group converter transformer valve side has a ground fault, the high-end and low-end valve groups of the fault pole of the fault station are locked, the alternating current switch of the fault pole layer is tripped, meanwhile, according to the first criterion, the phase meeting the criterion condition is defined as the fault phase, the bypass branch circuit conducting signal of the thyristor is locked, and the direct current side current is detected to be smaller than the preset value I dc_set And continues for a preset time t dc_set And then disconnecting the HSS switch with the fault pole, wherein the preset value I is obtained by combining the disconnection capability of the mechanical switch adopted in the practical engineering dc_set Is 15A, preset time t dc_set Is 15ms.
In the embodiment of the invention, the first type of fault and the second type of fault are both high-end valve banks and low-end valve banks of a lockout fault pole, and the difference is that the first type of fault needs to trigger the conduction of a thyristor bypass branch, but the second type of fault does not need to trigger the conduction of the thyristor bypass branch.
3) If the fault type is a third type fault, defining the faulted valve group as a valve group A, defining the other valve group which normally operates in the same pole as a valve group B (if the third type valve side fault occurs in the anode high-end valve group, defining the anode high-end valve group as the valve group A, defining the anode low-end valve group as the valve group B), executing a locking instruction on the valve group A, executing a zero-voltage control instruction on the valve group B, tripping off a valve layer alternating current switch of the valve group A, and waiting for the direct-current side voltage of the valve group A to be smaller than a preset value U dc_set When the direct current side BPS switch of the valve group A is closed, the invention is implementedIn the example, the preset value U is taken in combination with the on-off capacity of a mechanical switch adopted in actual engineering dc_set Is 5kV. And defining two phases meeting the criterion condition as fault phases according to a second criterion.
And 3, after the remote non-fault station receives the fault signals of the corresponding types from the fault station, executing corresponding control logic according to the types of the remote station and the fault signals, and completing the removal and restart of the fault.
In an embodiment of the present invention, the remote non-fault station includes: a sending end LCC station and a receiving end non-fault MMC station.
1) Aiming at a sending-end LCC station, if a received fault signal is a first-class fault or a second-class fault, namely, a high-end valve group converter transformer valve side has an earth fault or a low-end valve group converter transformer valve side has an earth fault, the high-end and low-end valve groups of a fault pole shift to 120 degrees, the high-end and low-end valve groups shift to 164 degrees after direct current is less than 250A, and the high-end and low-end valve groups of the fault pole simultaneously remove a phase shift instruction to execute restarting after the fault station is isolated; if the received fault signal is a third-class valve side fault, namely a two-phase interphase fault occurs at the high-end valve bank or the low-end valve bank converter transformer valve side, the high-end and low-end valve banks of the fault pole simultaneously execute a phase shifting instruction to 90 degrees, and when the voltage of the direct current side of the valve bank corresponding to the faulty valve bank (if the faulty valve bank of the fault MMC station is the anode high-end valve bank, the corresponding valve bank is the anode high-end valve bank of the LCC station) is smaller than a preset value U dc_set (in the embodiment of the invention, the preset value U is taken in combination with the on-off capacity of a mechanical switch adopted in practical engineering dc_set 5 kV), closing the corresponding valve bank direct current side BPS switch and locking the valve bank, tripping off a valve layer alternating current switch of the valve bank, and removing a phase shift instruction to recover the operation after the other valve bank of the sending end LCC station completes fault isolation;
2) Aiming at a receiving-end non-fault MMC station, if a received fault signal is a first-type fault or a second-type fault, namely a grounding fault occurs on the valve side of a high-end valve group converter transformer or a grounding fault occurs on the valve side of a low-end valve group converter transformer, the high-end and low-end valve groups of a fault pole execute a control voltage to zero instruction, and restart is executed after the fault station is isolated; if the received fault signal is a third type valve side fault, namely a high endWhen two-phase interphase fault occurs at the valve bank or the converter transformer valve side of the low-end valve bank, the high-end valve bank and the low-end valve bank of the fault pole simultaneously execute a command for controlling the voltage to be zero until the voltage at the direct-current side is smaller than a preset value U dc_set And when the fault isolation is finished, the other valve bank of the receiving-end non-fault MMC station recovers to operate after the fault isolation is finished.
For convenience of understanding, the following describes the flow of the method with reference to an actual case, and fig. 2 is a schematic structural diagram of an extra-high voltage three-terminal hybrid direct-current transmission system according to an embodiment of the present invention, where a sending end of the system is an LCC converter station (LCC 1), and a receiving end is two MMC converter stations (MMC 2 and MMC 3). The system adopts a true bipolar connection mode, each pole is formed by connecting two valve banks in series, the valve bank close to an overhead line is called a high-end valve bank, and the valve bank close to a grounding polar line is called a low-end valve bank. The method according to the embodiment of the invention will be described below by taking the case that different valve side faults occur at the positive electrode of the MMC2 station as an example, and specifically as follows:
1. if the phase a of the positive high-end valve group converter transformer of the MMC2 station is grounded, as shown in F1 in fig. 3, at this time, a valve side fault of the phase a is identified in the phase selection discrimination logic of the high-end valve group, a "1" signal is output, but the phase-to-phase fault discrimination logic of the high-end valve group does not work, a "0" signal is output, the signal is converted into a "1" signal after passing through a not gate, a first type fault signal is output after passing through an and gate logic with the phase selection logic signal, and meanwhile, the type of the fault is judged to be a phase-to-ground fault, and the low-end valve group does not output the fault signal because the phase selection discrimination logic does not work, and the specific flow is shown in fig. 4.
2. If the phase a of the converter transformer side of the very low end valve group of the MMC2 station is grounded, as shown in F2 in fig. 3, at this time, the phase selection discrimination logic of the low end valve group recognizes that the phase a fails, and outputs a "1" signal, but the phase-to-phase failure discrimination logic of the low end valve group does not work and outputs a "0" signal, and the signals are converted into a "1" signal after being inverted, and the signals and the phase selection logic signal output a second type of failure signal after passing through an and gate logic, and at the same time, the type of the failure is a phase-to-ground failure, and the high end valve group does not output the failure signal because the phase selection discrimination logic is not effective, and the specific flow is shown in fig. 4.
3. If an ab two-phase interphase fault occurs at the valve side of the converter transformer of the positive high-end valve group of the MMC2 station, as shown in F3 in fig. 3, at this time, the phase selection discrimination logic of the high-end valve group recognizes the ab phase fault, and outputs a "1" signal, meanwhile, the phase selection discrimination logic of the high-end valve group takes effect to output a "1" signal, and the phase selection logic signal pass through an and gate logic to output a third type fault signal, and at the same time, the type of the fault is an ab two-phase interphase fault. The low-end valve bank does not output a fault signal because the phase selection discrimination logic is not effective, and the specific flow is shown in fig. 4.
4. And the fault station MMC2 station executes different protection strategies according to three different fault signals.
As shown in fig. 5, for the first type of valve-side fault signal, the high-end and low-end valve groups of the positive electrode are simultaneously locked, the bypass branch of the phase unidirectional thyristor is triggered to be turned on according to the fault phase output by the phase selection logic of the high-end valve group, the alternating-current side switch of the positive electrode layer is skipped, the direct-current side current is detected to be less than 15A, and the HSS switch of the positive electrode is turned off after the direct-current side current lasts for 15ms.
As shown in fig. 6, for the second type of valve side fault signal, the positive high-side and low-side valve banks are simultaneously locked, the unidirectional thyristor bypass branch is locked, the positive pole layer ac side switch is tripped, the direct current side current is detected to be less than 15A, and the positive direct current pole HSS switch is turned off after 15ms.
As shown in fig. 7, for the third type of valve side fault signal, the positive high-end valve group is defined as a valve group a, the positive low-end valve group is defined as a valve group B, then the valve group a (positive high-end valve group) is locked, the valve group B (positive low-end valve group) executes the command of controlling the voltage to zero, the valve layer ac switch of the valve group a (positive high-end valve group) is tripped, and when the dc side voltage of the valve group a (positive high-end valve group) is less than 5kV, the dc side BPS switch of the valve group a (positive high-end valve group) is turned on.
5. As shown in fig. 5 to 7, the sending-end LCC1 station executes different logic outlets according to different types of valve side fault signals sent by the MMC2 station, and if the received fault signal is a first type or a second type of valve side fault, the phase of the high-end and low-end valve groups of the positive electrode is shifted to 120 °, and after the dc current is less than 250A, the phase is shifted to 164 °, and after the fault station is isolated, the high-end and low-end valve groups of the positive electrode simultaneously release the phase shift instruction to execute restart; if the received fault signal is a third-class valve side fault, the positive high-end valve bank and the positive low-end valve bank simultaneously execute a phase shift instruction to 90 degrees, the valve bank corresponding to the fault valve bank of the fault station is the positive high-end valve bank, and when the direct-current side voltage of the positive high-end valve bank is smaller than 5kV, the direct-current side BPS switch of the positive high-end valve bank is closed, the positive high-end valve bank is locked, and the valve layer alternating-current switch is opened. And the valve bank corresponding to the non-fault valve bank of the fault station is a positive electrode low-end valve bank which recovers operation after fault isolation.
6. As shown in fig. 5 to 7, the receiving-end MMC3 station executes different logic outlets according to different types of valve-side fault signals sent by the MMC2 station, and if the received fault signals are first or second types of valve-side faults, the high-end and low-end valve banks of the positive electrode immediately execute a command of controlling voltage to zero, and restart is executed after the fault station is isolated; if the received fault signal is a third-class valve side fault, the high-end and low-end valve groups of the positive electrode simultaneously execute a command for controlling the voltage to be zero, when the direct-current side voltage is smaller than 5kV, a direct-current side BPS switch of a valve group (a positive electrode high-end valve group) corresponding to the fault valve group of the fault station is switched on, the valve group is locked, and a valve side alternating-current switch is switched off. And the valve bank (positive electrode low-end valve bank) corresponding to the non-fault valve bank of the fault station recovers operation after fault isolation.
The technical scheme provided by the embodiment of the invention is suitable for an LCC-FHMMC hybrid extra-high voltage multi-terminal direct current transmission system with a high-low valve structure, and aiming at different types of valve side faults of a receiving-end MMC converter station, the valve side fault types are divided into three types according to whether the valve side faults meet two criteria provided by the invention, and corresponding protection strategies are executed according to different fault types, so that the faults are quickly removed, and the restarting of non-fault valves or stations is realized. The phase selection type unidirectional thyristor bypass branch circuit provided by the invention can effectively inhibit the direct-current line energy from charging the upper bridge arm submodule capacitor and plays a role in protecting the submodule capacitor aiming at the valve side ground fault of the high-end valve bank.
Through the description of the above embodiments, it is clear to those skilled in the art that the above embodiments may be implemented by software, or by software plus a necessary general hardware platform. With this understanding, the technical solutions of the embodiments can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a usb disk, a removable hard disk, etc.), and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods according to the embodiments of the present invention.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are also within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (5)
1. A fault protection method for a receiving end valve side of an extra-high voltage hybrid multi-end direct current transmission system is characterized by comprising the following steps:
when a converter transformer valve side of a receiving-end MMC station fails, respectively detecting whether the converter transformer valve side of the receiving-end MMC station has a fault or not and whether the valve side fault is a two-phase interphase fault or not through preset first and second judgment data;
determining the fault type by combining the detection result, executing corresponding protection strategies according to different fault types, and sending fault signals of corresponding types to a remote non-fault station;
after receiving the fault signals of the corresponding types from the fault station, the remote non-fault station executes corresponding control logic according to the types of the remote station and the fault signals to complete the removal and restart of the fault;
wherein the first criterion is expressed as:
|I vcn_x -I vtn_x |＞I set ＝k*I VPEAK_NOM
wherein, I vcn_x 、I vtn_x Respectively, ac bus valve side and current conversion in stationThe variable valve side sleeve current measuring points are represented by n = a, b, c, x = h, a high-end valve group measuring point is represented by x = l, a low-end valve group measuring point is represented by k, a proportionality coefficient is I VPEAK_NOM Showing the peak value of the alternating-current phase current in a steady state; two valve banks are connected in series in a receiving-end MMC station, a valve bank close to a direct current polar line is called a high-end valve bank, and a valve bank close to a grounding polar line is called a low-end valve bank;
the second criterion is expressed as:
U ta_x ＝U tb_x ≠0 or U ta_x ＝U tc_x ≠0 or U tb_x ＝U tc_x ≠0
wherein, U tn_x Phase voltages of a three-phase alternating current bus at the side of a converter transformer valve are represented, n = a, b, c, x = h represents a high-end valve group measuring point, x = l represents a low-end valve group measuring point, and or represents a relation that three discriminants take logical OR;
the remote station includes: a sending end LCC station and a receiving end non-fault MMC station;
aiming at a sending-end LCC station, if a received fault signal is a first-class fault or a second-class fault, namely, a high-end valve group converter transformer valve side has an earth fault or a low-end valve group converter transformer valve side has an earth fault, phase shifting of a high-end valve group and a low-end valve group of a fault pole is 120 degrees, phase shifting is carried out to 164 degrees after direct current is less than 250A, and after the fault station is isolated, phase shifting instructions are simultaneously released from the high-end valve group and the low-end valve group of the fault pole to restart the fault; if the received fault signal is a third-class valve side fault, namely a two-phase interphase fault occurs on the valve side of the converter transformer of the high-end valve bank or the low-end valve bank, the high-end valve bank and the low-end valve bank of the fault pole simultaneously execute a command of shifting the phase to 90 degrees, and when the direct-current side voltage of the valve bank corresponding to the failed valve bank is smaller than a preset value U dc_set When the fault isolation is finished, the phase shift instruction is released to recover the operation of the other valve bank;
aiming at a receiving-end non-fault MMC station, if a received fault signal is a first fault or a second fault, namely, a high-end valve group converter transformer valve side has an earth fault or a low-end valve group converter transformer valve side has an earth fault, the high-end and low-end valve groups of a fault pole execute a control voltage to zero instruction, and a station to be subjected to fault is isolatedRestarting is executed after the power failure; if the received fault signal is a third-class valve side fault, namely a two-phase interphase fault occurs at the high-end valve bank or the low-end valve bank converter transformer valve side, the high-end valve bank and the low-end valve bank which have the fault simultaneously execute a command of controlling voltage to be zero, and when the voltage of the direct-current side is smaller than a preset value U dc_set When the fault isolation is finished, the valve group direct current side BPS switch corresponding to the valve group with the fault is closed, the corresponding valve group is locked, the valve side alternating current switch is tripped, and the other valve group is recovered to operate after the fault isolation is finished.
2. The method for protecting the receiving end valve side fault of the extra-high voltage hybrid multi-end direct current transmission system according to claim 1, wherein the step of respectively detecting whether the valve side of the converter transformer of the receiving end station has the fault or not and whether the valve side fault is the two-phase-to-phase fault or not according to preset first and second judgment data comprises the steps of:
if the high-end valve group judging logic meets the condition that the first criterion does not meet the second criterion, judging that the valve side of the converter transformer of the high-end valve group has an earth fault, and defining the fault as a first type of fault;
if the low-end valve group judging logic meets the condition that the first criterion does not meet the second criterion, judging that the valve side of the low-end valve group converter transformer has an earth fault, and defining the low-end valve group converter transformer as a second type of fault;
if the high-end valve group or low-end valve group judging logic simultaneously meets the first and second judging data, judging that two-phase interphase faults occur at the valve side of the converter transformer of the high-end valve group or low-end valve group, and defining the faults as a third type of faults;
two valve banks are connected in series in the receiving-end MMC station, wherein the valve bank close to a direct current polar line is called a high-end valve bank, and the valve bank close to a ground polar line is called a low-end valve bank.
3. The method for protecting the fault at the receiving end valve side of the extra-high voltage hybrid multi-end direct current transmission system according to claim 1 or 2, characterized in that if the fault type is a first type of fault, namely, the earth fault occurs at the converter valve side of the high-end valve group, the high-end and low-end valve groups of the fault pole of the fault station are locked, the alternating current switch at the pole layer of the fault pole is tripped, and meanwhile, according to a first criterion, the phase meeting the criterion condition is defined as the fault pole layer alternating current switchAnd the phase triggers the bypass branch of the fault phase unidirectional thyristor to be conducted, and detects that the direct current side current is less than a preset value I dc_set And continues for a preset time t dc_set And then the HSS switch of the fault pole is switched off.
4. The method according to claim 1 or 2, wherein if the fault type is a second type of fault, namely a ground fault occurs at the converter valve side of the low-end valve group, the high-end and low-end valve groups of a fault pole of a fault station are locked, the alternating current switch of the fault pole layer is tripped, meanwhile, according to a first criterion, a phase meeting a criterion condition is defined as a fault phase, a thyristor bypass branch circuit conducting signal is locked, and a direct current side current is detected to be smaller than a preset value I dc_set And continues for a preset time t dc_set And then the HSS switch of the fault pole is switched off.
5. The method for protecting the fault on the receiving end valve side of the extra-high voltage hybrid multi-end direct current transmission system according to claim 1 or 2, wherein if the fault type is a third type of fault, namely a two-phase interphase fault occurs on the high-end valve bank or the low-end valve bank converter transformer valve side,
defining a valve group with a fault as a valve group A, defining another valve group with the same pole and normal operation as a valve group B, executing a locking instruction on the valve group A, executing a zero pressure control instruction on the valve group B, tripping off a valve layer alternating current switch of the valve group A, and waiting for the direct current side voltage of the valve group A to be smaller than a preset value U dc_set When the direct-current side BPS switch of the valve group A is closed, and meanwhile two phases meeting the criterion condition are defined as fault phases according to a second criterion.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105186451A (en) * | 2015-08-27 | 2015-12-23 | 南京国电南自电网自动化有限公司 | Inrush current lock self-adaptive switching method for earth fault in valve side region of converter transformer |
| CN109980613A (en) * | 2019-03-12 | 2019-07-05 | 天津大学 | Based on the direct-flow distribution system fault recovery method for improving half-bridge submodule |
| WO2019227979A1 (en) * | 2018-05-28 | 2019-12-05 | 南京南瑞继保电气有限公司 | Hybrid direct current converter valve group online feed circuit and feed method and apparatus |
| CN111769526A (en) * | 2020-07-07 | 2020-10-13 | 北京四方继保自动化股份有限公司 | Valve group fault exit control method for extra-high voltage multi-terminal hybrid direct-current transmission system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106058826B (en) * | 2016-06-03 | 2018-08-17 | 南京南瑞继保电气有限公司 | A kind of mixed type DC transmission system receiving end exchange side fault handling method |
-
2021
- 2021-02-01 CN CN202110137503.3A patent/CN112865038B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105186451A (en) * | 2015-08-27 | 2015-12-23 | 南京国电南自电网自动化有限公司 | Inrush current lock self-adaptive switching method for earth fault in valve side region of converter transformer |
| WO2019227979A1 (en) * | 2018-05-28 | 2019-12-05 | 南京南瑞继保电气有限公司 | Hybrid direct current converter valve group online feed circuit and feed method and apparatus |
| CN109980613A (en) * | 2019-03-12 | 2019-07-05 | 天津大学 | Based on the direct-flow distribution system fault recovery method for improving half-bridge submodule |
| CN111769526A (en) * | 2020-07-07 | 2020-10-13 | 北京四方继保自动化股份有限公司 | Valve group fault exit control method for extra-high voltage multi-terminal hybrid direct-current transmission system |
Non-Patent Citations (2)
| Title |
|---|
| 基于LCC-MMC的三端混合直流输电系统故障特性与控制保护策略;洪潮等;《电力建设》;20170801(第08期);全文 * |
| 祁韶±800 kV特高压直流输电工程两种故障重启动逻辑研究;徐浩等;《电力系统保护与控制》;20180627(第12期);全文 * |
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