CN110970879A - Method and device for controlling valve area ground fault of extra-high voltage direct current low-side converter - Google Patents
Method and device for controlling valve area ground fault of extra-high voltage direct current low-side converter Download PDFInfo
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- CN110970879A CN110970879A CN201911368626.7A CN201911368626A CN110970879A CN 110970879 A CN110970879 A CN 110970879A CN 201911368626 A CN201911368626 A CN 201911368626A CN 110970879 A CN110970879 A CN 110970879A
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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]
Abstract
The application provides a method and a device for controlling an earth fault of a valve area of an extra-high voltage direct current low-end converter. The control method and the control device are applied to a low-end converter of a direct current pole of an extra-high voltage direct current transmission system, the extra-high voltage direct current transmission system comprises a double direct current pole, the direct current pole comprises at least two converters connected in series, the low-end converter is a converter close to a pole neutral bus, when the double direct current poles of the extra-high voltage direct current transmission system operate and the direct current pole where the low-end converter is located operates in a full valve group mode, and a ground fault is detected in a valve area of the low-end converter, the control method comprises the following steps: controlling the low-side converter to be locked; controlling the direct current of the double direct current poles of the extra-high voltage direct current transmission system to be equal; isolating the low-side converter; the converters other than the low side converter continue to operate.
Description
Technical Field
The application relates to the technical field of high-voltage direct-current transmission, in particular to a method and a device for controlling an earth fault of a valve area of an extra-high voltage direct-current low-side converter.
Background
The ultra-high voltage direct current transmission system generally adopts two converters connected in series to form a direct current pole, and is divided into a conventional ultra-high voltage direct current transmission system, a layered access ultra-high voltage direct current transmission system and a mixed ultra-high voltage direct current transmission system according to the existing engineering.
The conventional extra-high voltage direct current transmission system is characterized in that a high-end converter and a low-end converter of one direct current pole are both power grid phase-change converters and are connected to the same alternating current power grid. The layered access extra-high voltage direct current transmission system is characterized in that a high-end converter and a low-end converter of one direct current pole are power grid phase-change converters and are respectively accessed to two different alternating current power grids. The hybrid extra-high voltage direct current transmission system is divided into two types: the mixed extra-high voltage direct current transmission system of the inter-station mixing adopts a direct current pole high-end converter and a direct current pole low-end converter of a converter station of a voltage source converter as the voltage source converter, the mixed extra-high voltage direct current transmission system of the inter-station mixing adopts a direct current pole high-end converter and a direct current pole low-end converter of the voltage source converter as the voltage source converter, and the mixed extra-high voltage direct current transmission system of the inter-station mixing adopts a power grid commutation converter and a direct current pole high-end converter and a direct current pole low-end converter of the voltage source converter as the power grid commutation converter and the voltage source converter.
When the bipolar balanced operation of an extra-high voltage direct current transmission system is carried out, when the converter detects the grounding fault of a converter valve area, the fault is isolated by locking the whole direct current pole in the prior art, and after the fault is isolated, the bipolar balanced operation is realized by adopting a single-pole ground return wire to continue the operation, or turning a metal return wire to operate, or restarting a non-fault converter of the direct current pole.
The prior art mainly has the following problems: after the whole direct current pole is locked, a large current flows through the grounding pole line, so that a transformer of a nearby transformer substation is easy to have direct current magnetic bias, and the transformer is saturated; after the whole direct current pole is locked, if the transmission power is larger, more direct current power is lost; after the entire dc pole is blocked, more fault current flows through the fault point.
Therefore, when the bipolar balance operation of the extra-high voltage direct current transmission system is carried out, when the converter detects the grounding fault of the valve area of the converter, the whole direct current pole is not locked under certain working conditions as much as possible, and only the converter with the fault is locked.
Disclosure of Invention
The embodiment of the application provides an extra-high voltage direct current low-side converter valve area ground fault control method, which is applied to a low-side converter of a direct current pole of an extra-high voltage direct current transmission system, wherein the extra-high voltage direct current transmission system comprises a double direct current pole, the direct current pole comprises at least two converters connected in series, the low-side converter is a converter close to a pole neutral bus, and when the double direct current poles of the extra-high voltage direct current transmission system operate and the direct current pole where the low-side converter is located operates in a full valve group, and a ground fault in a valve area of the low-side converter is detected, the control method comprises the following steps: controlling the low-side converter to be locked; controlling the direct current of the double direct current poles of the extra-high voltage direct current transmission system to be equal; isolating the low-side converter; the converters other than the low side converter continue to operate.
According to some embodiments, the low side converter comprises at least one of a grid commutated converter or a voltage source converter.
According to some embodiments, the dual dc pole operation comprises: each direct current pole is provided with at least one converter in operation; the full valve bank operation comprises: and the direct current pole of the low-side converter is provided with at least one converter in operation besides the low-side converter.
According to some embodiments, the low side converter has a valve area with a ground fault, comprising: and the low-side converter has at least one of a ground fault, a ground fault of a connecting line between the low-side converter and the converter transformer, and a ground fault of a valve side winding of the converter transformer.
According to some embodiments, the detecting of the ground fault in the valve area of the low-side converter comprises: and detecting that the absolute value of the difference between the high-voltage bus current and the low-voltage bus current on the direct current side of the low-side converter is greater than a set current difference value.
According to some embodiments, if the low side converter is a voltage source converter, said controlling the low side converter to latch comprises: and controlling the low-side converter to stop triggering pulses, closing a second bypass switch of a low-side valve group where the low-side converter is located, and tripping off a converter transformer incoming line switch of the low-side converter, wherein the second bypass switch is connected with the anode and the cathode of the low-side converter.
According to some embodiments, if the low side converter is a grid commutated converter, said controlling said low side converter blocking comprises: when the low-side converter operates in a rectifying mode, selecting a first locking mode of the rectifying side converter or a second locking mode of the rectifying side converter to control the low-side converter to be locked; and when the low-side converter operates in an inverting mode, selecting a first locking mode of the inverting side converter or a second locking mode of the inverting side converter to control the low-side converter to be locked.
According to some embodiments, the first blocking mode of the rectifier side converter comprises: the low-end converter which controls the rectification operation stops sending trigger pulses, and the corresponding converter which controls the inversion operation has a trigger angle of 90 degrees; and controlling to trip off a converter transformer incoming line switch of the low-side converter, closing a second bypass switch of the low-side converter, putting the corresponding inverter-operated converter into a bypass pair, and closing the bypass switch, wherein the second bypass switch is connected with the anode and the cathode of the low-side converter.
According to some embodiments, the second blocking manner of the rectifier side converter comprises: controlling the low-side converter to be put into a bypass pair, closing a second bypass switch, and simultaneously tripping on an incoming line switch of a converter transformer of the low-side converter, wherein a trigger angle of the corresponding inverter-operated converter is controlled to be 90 degrees, and the second bypass switch is connected with an anode and a cathode of the low-side converter; and controlling the converter in the corresponding inversion operation to be put into the bypass pair, and closing the bypass switch.
According to some embodiments, the first locking mode of the inverter-side converter comprises: controlling a converter transformer incoming switch of the low-side converter which is in trip inversion operation, putting a bypass pair, closing a second bypass switch, controlling a trigger angle of the corresponding converter in rectification operation to be 90 degrees, and connecting the second bypass switch with the anode and the cathode of the low-side converter; and controlling the converter which correspondingly rectifies and operates to be put into a bypass pair, and closing a bypass switch.
According to some embodiments, the second locking manner of the inverter-side converter comprises: the low-side converter for controlling the inversion operation is put into a bypass pair, a second bypass switch is closed, a converter transformer incoming line switch of the low-side converter is tripped, a corresponding converter for rectifying operation has a control trigger angle of 90 degrees, and the second bypass switch is connected with the anode and the cathode of the low-side converter; and controlling the converter which correspondingly rectifies and operates to be put into a bypass pair, and closing a bypass switch.
According to some embodiments, the controlling the direct currents of the double direct current poles of the extra-high voltage direct current transmission system to be equal comprises: giving the same direct current reference value of the current converter with double direct current poles; controlling high-voltage bus current or low-voltage bus current or pole bus current of converters other than the low-side converter to be the direct current reference value; the direct current reference value is determined according to active power, reactive power, fault current limit or ground current limit requirements of the ultra-high voltage direct current transmission system; if the faulted low-side converter operates in a rectifying mode, the converters on the rectifying side except the low-side converter adopt current control to control the direct current of the converters on the rectifying side except the low-side converter to be equal, and the converter on the inverting side operates in maximum trigger angle control or direct current voltage control; if the low-side converter with the fault runs in an inverting mode, the converters on the inverting side except the low-side converter send fault information to the rectifying side, the rectifying side controls the direct currents of the converters with the double direct-current poles to be equal, or current control is adopted to control the direct currents of the converters on the inverting side except the low-side converter to be equal, and the converter on the rectifying side runs in direct-current voltage control.
According to some embodiments, said isolating said low side converter comprises: the low-side switch is connected with the low-side converter in parallel, the second bypass switch is connected with two ends of the low-side converter, the valve group switch is connected with the low-side converter and the valve group connecting wire, and the bus switch is connected with the low-side converter and a polar neutral bus.
According to some embodiments, if the open current constant values of the second bypass switch, the group valve switch and the bus switch are all smaller than the larger of the high voltage bus current or the low voltage bus current on the dc side of the low side converter, the isolating the low side converter comprises: if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the valve group switch is separated, the double-direct-current-pole direct current is controlled to be zero, the second bypass switch is separated again, the double-direct-current-pole direct current is recovered, and then the bus switch is separated; and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the bus switch is separated, the double-direct-current-pole direct current is controlled to be zero, the second bypass switch is separated again, the double-direct-current-pole direct current is recovered, and then the valve group switch is separated.
According to some embodiments, if the divided current constant value of any one of the second bypass switch, the group switch and the bus switch is greater than the larger of the high voltage bus current or the low voltage bus current on the dc side of the low-side converter, and the divided current constant value of the second bypass switch is the largest, the dividing of the second bypass switch, the group switch and the bus switch of the low-side converter comprises: if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the valve group switch is firstly separated, then the second bypass switch is separated, and then the bus switch is separated; and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the bus switch is firstly separated, then the second bypass switch is separated, and then the valve group switch is separated.
According to some embodiments, if the divided current constant value of any one of the second bypass switch, the group switch and the bus switch is greater than the larger of the high voltage bus current or the low voltage bus current on the dc side of the low-side converter and the divided current constant value of the group switch is the largest, the dividing of the second bypass switch, the group switch and the bus switch of the low-side converter comprises: if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the second bypass switch is firstly separated, then the valve group switch is separated, and then the bus switch is separated; and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the bus switch is firstly separated, then the valve group switch is separated, and then the second bypass switch is separated.
According to some embodiments, if the divided current constant value of any one of the second bypass switch, the group switch and the bus switch is greater than the larger of the high voltage bus current or the low voltage bus current on the dc side of the low-side converter and the divided current constant value of the bus switch is the largest, the dividing of the second bypass switch, the group switch and the bus switch of the low-side converter comprises: if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the valve group switch is firstly separated, then the bus switch is separated, and then the second bypass switch is separated; and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the second bypass switch is firstly separated, then the bus switch is separated, and then the valve group switch is separated.
According to some embodiments, the converters other than the low side converter continue to operate, comprising: and the current converters of the station where the low-end current converter is located except the low-end current converter continue to operate, other stations quit the current converters corresponding to the low-end current converter, and the rest current converters continue to operate.
According to some embodiments, before isolating the low-side converter, further comprising: and increasing the pole difference protection differential current constant value of the direct current pole of the low-end converter, or increasing the pole difference protection delay constant value of the direct current pole of the low-end converter or shielding the pole difference protection until the low-end converter is isolated.
According to some embodiments, after controlling the low-side inverter to be locked, the method further includes: and pulling a metal return line change-over switch or a neutral bus grounding switch to disconnect the connection between the converter station and the ground, wherein the metal return line change-over switch is connected with the bipolar neutral bus and the grounding electrode circuit, and the neutral bus grounding switch is connected with the bipolar neutral bus and the grounding network in the station.
According to some embodiments, if the metallic return switch or neutral bus grounding switch is pulled open, the control method further comprises: and after the low-side converter is isolated, closing the metal return wire change-over switch or the neutral bus grounding switch.
The embodiment of the application also provides an extra-high voltage direct current low-side converter valve area ground fault control device, wherein the extra-high voltage direct current low-side converter valve area ground fault control method is applied to the control device, the control device comprises a detection unit and a control unit, the detection unit detects high-voltage bus current and low-voltage bus current of the low-side converter, detects polar neutral bus current, detects high-voltage bus current, low-voltage bus current or polar bus current of a converter except the low-side converter, where the low-side converter is located, and detects polar bus voltage and polar neutral bus voltage; and the control unit judges that the extra-high voltage direct current transmission system operates at double direct current poles, controls the low-end converter to be locked when the direct current pole where the low-end converter is located operates at a full valve group and detects that the valve area of the low-end converter has a ground fault, controls the direct current of the double direct current poles to be equal, isolates the low-end converter and controls the converters except the low-end converter to continue to operate.
The technical scheme that this application embodiment provided, when the balanced operation of the two direct current utmost point of extra-high voltage direct current transmission system, the low end transverter place direct current is for full valve group operation and when detecting low end transverter valve zone earth fault, whole direct current utmost point of not shutting, but only the low end transverter of shutting the trouble, through bipolar balance control, on leading-in the utmost point busbar of trouble utmost point with the extremely electric current of normal operating, thereby avoid the extremely electric current of normal operating to flow into the fault point excessively, guarantee more transverters operation simultaneously, avoid losing great direct current transmission power.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, 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 application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic diagram of a main loop of an extra-high voltage direct current transmission system according to an embodiment of the present application;
FIG. 2 is a schematic flow chart of a method for controlling a valve area ground fault of an extra-high voltage direct current low-side converter according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a valve area ground fault control device of an extra-high voltage direct current low-side converter according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be understood that the terms "first," "second," "third," "fourth," and the like in the claims, the description, and the drawings of the present application are used for distinguishing between different objects and not for describing a particular order. The term "comprises/comprising" when used in the specification and claims of this application is taken to specify the presence of stated features, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Fig. 1 is a schematic diagram of a main loop of an extra-high voltage direct current transmission system according to an embodiment of the present application.
The main loop of the extra-high voltage direct current transmission system comprises a rectifying station 100, an inverter station 200, a first direct current line 150, a second direct current line 160, a rectifying station grounding electrode line 114, a rectifying station grounding electrode 115, an inverter station grounding electrode line 214 and an inverter station grounding electrode 215.
The rectifier station 100 comprises a first dc pole I110, a second dc pole II120, a first ac filter bank 118, a first ac system 140, and a converter transformer incoming line switch and metallic return line transfer switch 113.
The first dc pole I110 includes a first high-side valve group 111, a first low-side valve group 112, a first high-side converter transformer 116, a first low-side converter transformer 117, a first dc filter 93, and a first smoothing reactor 91. First high side valve block 111 and first low side valve block 112 are connected in series.
The first high-end valve group 111 includes a first high-end converter 1, a first high-end valve group first bypass switch 11, a first high-end valve group second bypass switch 12, a first high-end valve group bus switch 13, and a first high-end valve group switch 14. The first high-side valve block first bypass switch 11 is connected in parallel with the first high-side converter 1. The first high-side valve group second bypass switch 12 is connected to two ends of the first high-side converter 1. The first high-side valve bank switch 14 is connected with the first high-side converter 1 and the valve bank connecting line. The first high-side valve group bus switch 13 connects the first high-side converter 1 and the pole bus.
The first low side bank 112 includes a first low side inverter 2, a first low side bank first bypass switch 21, a first low side bank second bypass switch 22, a first low side bank switch 23, and a first low side bank bus switch 24. A first low side group valve first bypass switch 21 is connected in parallel with the first low side converter 2, a first low side group valve second bypass switch 22 is connected to both ends of the third low side converter 6, a first low side group valve switch 23 is connected to the first low side converter 2 and the group valve connection line, and a first low side group bus switch 24 is connected to the first low side converter 2 and the polar neutral bus.
The first high side converter 1 and the first low side converter 2 comprise at least one of a grid commutated converter or a voltage source converter.
The grid commutation converter comprises at least one of a six-pulse bridge circuit and a twelve-pulse bridge circuit. The ripple bridge circuit includes, but is not limited to, a non-turn-off semi-controlled power semiconductor device, typically a thyristor device.
The voltage source converter comprises at least one of a two-level converter, a diode clamping type multi-level converter, a modular multi-level converter MMC, a hybrid multi-level converter HMC, a two-level cascade converter CSL and a stacking type two-level converter CTL, and the voltage source converter comprises but is not limited to a turn-off fully-controlled power semiconductor device. The modular multilevel converter MMC comprises but is not limited to at least one of a modular multilevel converter MMC with a half-bridge sub-module structure, a modular multilevel converter MMC with a full-bridge sub-module structure and a modular multilevel converter MMC with a half-bridge and full-bridge mixed sub-module structure.
The second dc pole II120 includes a second low-side valve block 121, a second high-side valve block 122, a second low-side converter transformer 126, a second high-side converter transformer 127, a second dc filter 94, and a second smoothing reactor 92. The second low side valve block 121 and the second high side valve block 122 are connected in series.
The second high-side valve group 122 includes a second high-side converter 4, a second high-side valve group first bypass switch 41, a second high-side valve group second bypass switch 42, a second high-side valve group switch 43, and a second high-side valve group bus switch 44. A second high-end valve bank first bypass switch 41 is connected in parallel with the second high-end converter 4, a second high-end valve bank second bypass switch 42 is connected with two ends of the second high-end converter 4, a second high-end valve bank switch 43 is connected with the second high-end converter 4 and a valve bank connecting line, and a second high-end valve bank bus switch 44 is connected with the second high-end converter 4 and a pole bus.
The second low side valve block 121 includes a second low side inverter 3, a second low side valve block first bypass switch 31, a second low side valve block second bypass switch 32, a second low side valve block bus switch 33, and a second low side valve block switch 34. A second low end group first bypass switch 31 is connected in parallel with the second low end converter 3, a second low end group second bypass switch 32 is connected to both ends of the second low end converter 3, a second low end group switch 34 is connected to the second low end converter 3 and the group connection line, and a second low end group bus switch 33 is connected to the second low end converter 3 and the polar neutral bus.
The second high side converter 4 and the second low side converter 3 comprise at least one of a grid commutated converter or a voltage source converter.
The inverter station 200 comprises a third dc pole I210, a fourth dc pole II220, a second ac filter bank 218, a second ac system 240 and a converter transformer incoming line switch.
The third dc pole I210 includes a third high-side valve group 211, a third low-side valve group 212, a third high-side converter transformer 216, a third low-side converter transformer 217, a third dc filter 97, and a third smoothing reactor 95. The third high-side valve set 211 and the third low-side valve set 212 are connected in series.
The third high side valve group 211 includes a third high side converter 5, a third high side valve group first bypass switch 51, a third high side valve group second bypass switch 52, a third high side valve group bus switch 53, and a third high side valve group switch 54. The third high-end valve group first bypass switch 51 is connected with the third high-end converter 5 in parallel, the third high-end valve group second bypass switch 52 is connected with two ends of the third high-end converter 5, the third high-end valve group switch 54 is connected with the third high-end converter 5 and a valve group connecting line, and the third high-end valve group bus switch 53 is connected with the third high-end converter 5 and a pole bus.
The third low side valve block 212 includes a third low side inverter 6, a third low side valve block first bypass switch 61, a third low side valve block second bypass switch 62, a third low side valve block switch 63, and a third low side valve block bus switch 64. A third low side group first bypass switch 61 is connected in parallel with the third low side inverter 6, a third low side group second bypass switch 62 is connected to both ends of the third low side inverter 6, a third low side group switch 63 is connected to the third low side inverter 6 and the group connection line, and a third low side group bus switch 64 is connected to the third low side inverter 6 and the pole neutral bus.
The third high-side converter 5 and the third low-side converter 6 comprise at least one of a grid commutated converter or a voltage source converter.
The fourth dc pole II220 includes a fourth low-side valve group 221, a fourth high-side valve group 222, a fourth low-side converter transformer 226, a fourth high-side converter transformer 227, a second dc filter 98, and a second smoothing reactor 96. The fourth low side valve block 221 and the fourth high side valve block 222 are connected in series.
The fourth high-side valve group 222 includes a fourth high-side converter 8, a fourth high-side valve group first bypass switch 81, a fourth high-side valve group second bypass switch 82, a fourth high-side valve group switch 83, and a fourth high-side valve group bus switch 84. The fourth high-end valve group first bypass switch 81 is connected in parallel with the fourth high-end converter 8, the fourth high-end valve group second bypass switch 82 is connected with two ends of the fourth high-end converter 8, the fourth high-end valve group switch 83 is connected with the fourth high-end converter 8 and the valve group connecting line, and the fourth high-end valve group bus switch 84 is connected with the fourth high-end converter 8 and the pole bus.
The fourth low side bank 221 includes a fourth low side inverter 7, a fourth low side bank first bypass switch 71, a fourth low side bank second bypass switch 72, a fourth low side bank bus switch 73, and a fourth low side bank switch 74. A fourth low side group valve first bypass switch 71 is connected in parallel with the fourth low side converter 7, a fourth low side group valve second bypass switch 72 is connected to both ends of the fourth low side converter 7, a fourth low side group valve switch 74 is connected to the fourth high side converter 7 and the group connection line, and a fourth low side group bus switch 73 is connected to the fourth low side converter 7 and the pole neutral bus.
The fourth high-side converter 8 and the fourth low-side converter 7 comprise at least one of a grid commutated converter or a voltage source converter.
The above mentioned switches include at least one of mechanical switches, knife switches, dc breakers, and thyristor valve sets.
If the high-side converter and the low-side converter of the dc pole of the rectifier station 100 and the inverter station 200 are both grid commutation converters, and the high-side converter and the low-side converter are connected to the same ac grid, the system is a conventional extra-high voltage dc transmission system.
If the high-end converter and the low-end converter of the direct current pole of the rectifying station 100 and the direct current pole of the inverting station 200 are both grid commutation converters, and the high-end converter and the low-end converter are connected with different alternating current grids, the ultrahigh voltage direct current transmission system is accessed in a layered mode.
If the first high-end converter 1, the first low-end converter 2, the second high-end converter 4 and the second low-end converter 3 of the first direct current pole I110 and the second direct current pole II120 of the rectifying station 100 are all grid commutation converters, and the third high-end converter 5, the third low-end converter 6, the fourth high-end converter 8 and the fourth low-end converter 7 of the third direct current pole I210 and the fourth direct current pole II220 of the inverting station 200 are all voltage source converters, a hybrid extra-high voltage direct current transmission system with hybrid stations is provided.
If the first high-side converter 1, the first low-side converter 2, the second high-side converter 4 and the second low-side converter 3 of the first dc pole I110 and the second dc pole II120 of the rectifying station 100 are all grid commutation converters, the third high-side converter 5 and the fourth high-side converter 8 of the third dc pole I210 and the fourth dc pole II220 of the inverting station 200 are grid commutation converters, and the third low-side converter 6 and the fourth low-side converter 7 are voltage source converters, an intra-pole hybrid ultra-high voltage dc transmission system is provided.
The rectifier station 100 is connected to an earth 115 via an earth line 114. The inverter station 200 is connected to a ground 215 via a ground line 214. When power is being transmitted, the first ac system 140 of the rectifying station 100 converts ac power into dc power through the first high-side converter 1, the first low-side converter 2, the second high-side converter 4 and the second low-side converter 3, and transmits the dc power to the inverter station 200 through the dc lines 150 and 160, and the inverter station 200 converts dc power into ac power through the third high-side converter 5, the third low-side converter 6, the fourth high-side converter 8 and the fourth low-side converter 7, and transmits the ac power to the second ac system 240 of the inverter station 200, thereby realizing the direct power transmission. The converters of the rectifier stations generally operate in current control, and the converters of the inverter stations generally operate in voltage control or maximum firing angle control (AMAX). It is noted that the maximum firing angle control (AMAX) is only applicable to grid commutated converters and not to voltage source converters.
The analog quantity signals collected by the rectification station 100 and the inversion station 200 are: high-voltage bus current IDC1P, low-voltage bus current IDC1N at the dc side of the high-side converter, high-voltage bus current IDC2P, low-voltage bus current IDC2N at the dc side of the low-side converter, pole-neutral bus current IDC, pole-bus current IDL, pole-bus voltage UDL, and pole-neutral bus voltage UDN.
Fig. 2 is a schematic flow chart of a method for controlling a valve area ground fault of an extra-high voltage direct current low-side converter according to an embodiment of the present application.
The extra-high voltage direct current transmission system comprises double direct current poles, each direct current pole comprises at least two converters connected in series, and the low-end converter is a converter close to a pole neutral bus. The technical term definitions are as follows.
Double-direct-current-pole operation: at least one inverter is in operation per dc pole.
The whole valve group operates: at least two inverters are in operation in the dc stage.
And (3) the valve area of the low-end converter is in ground fault: the method comprises at least one of the grounding fault of the low-end converter, the grounding fault of a connecting line between the low-end converter and the converter transformer and the grounding fault of a valve side winding of the converter transformer.
Detecting a ground fault in the valve area of the low-side converter: and detecting that the absolute value of the difference between the high-voltage bus current and the low-voltage bus current on the direct current side of the low-side converter is greater than the set current difference value.
The occurrence of the earth fault in the valve area of the low-end converter is judged through the differential protection action of the converter, and the criterion formula of the differential protection action of the converter is as follows.
IDiff_v＝|IDC2P–IDC2N|，
IRes_v＝|IDC2P+IDC2N|/2，
IDiff_v>max(Iv_set,kv_set*IRes_v)；
IDC2P is a high-voltage bus current on the direct current side of the low-end converter, IDC2N is a low-voltage bus current on the direct current side of the low-end converter, Iv _ set is a starting current fixed value, and kv _ set is a ratio coefficient.
When the ultrahigh voltage direct current transmission system operates with double direct current poles and the direct current pole where the low-end converter is located is operated with a full valve group, namely the high-end converter and the low-end converter of one direct current pole operate simultaneously and at least one converter of the other direct current pole operates, and the low-end converter of one direct current pole detects that the valve area of the low-end converter has an earth fault, the control method is as follows.
In S110, the low-side inverter is controlled to be locked.
And if the low-side converter is a voltage source converter, controlling the low-side converter to be locked to immediately stop sending trigger pulses, closing a second bypass switch of a valve group where the low-side converter is located, tripping on a converter transformer incoming line switch of the low-side converter, and connecting the second bypass switch with the anode and the cathode of the low-side converter.
Taking the first low-side converter 2 as an example, if the first low-side converter 2 is a voltage source converter, the first low-side converter 2 is controlled to latch to immediately stop triggering pulse, the first low-side valve set second bypass switch 22 is closed, the first low-side converter transformer incoming line switch 132 of the first low-side converter 2 is tripped, and the first low-side valve set second bypass switch 22 is connected to the positive pole and the negative pole of the first low-side converter 2.
If the low-side converter is a power grid commutation converter, controlling the low-side converter to lock and select different locking modes according to the operation in a rectification or inversion state, and when the low-side converter operates in a rectification mode, selecting any one of the following two locking modes: the first locking mode of the rectifying side converter and the second locking mode of the rectifying side converter. When the low-side converter operates in an inversion mode, selecting any one of the following two locking modes: the first locking mode of the inversion side converter and the second locking mode of the inversion side converter.
Taking the rectifying station 100 as an example, if the first low-side converter 2 of the first dc pole I110 is in rectifying operation, if the first blocking mode of the rectifying-side converter is adopted: the first low-side converter 2 of the first direct current pole I110 of the rectifying station 100 immediately stops triggering pulses, and the third low-side converter 6 of the third direct current pole I210 of the inverter station 200 controls a triggering angle to be 90 degrees; the first low-side converter 2 of the first dc pole I110 of the rectifying station 100 trips the first low-side converter transformer incoming switch 132, the first low-side valve set second bypass switch 22 is closed, the third low-side converter 6 of the third dc pole I210 of the inverter station 200 is put into a bypass pair, and the third low-side valve set second bypass switch 62 is closed.
Taking the rectifying station 100 as an example, if the first low-side converter 2 of the first dc pole I110 is in rectifying operation, if the second latching mode of the rectifying-side converter is adopted: a first low-end converter 2 of a first direct current pole I110 of the rectifier station 100 is put into a bypass pair, a second bypass switch 22 of a first low-end valve bank is closed, a first low-end converter transformer incoming line switch 132 is opened, and a third low-end converter 6 of a third direct current pole I210 of the inverter station 200 is controlled to have a trigger angle of 90 degrees; the third low-side inverter 6 of the third dc pole I210 of the inverter station 200 is put into the bypass pair, and the third low-side valve bank second bypass switch 62 is closed.
Taking the inverter station 200 as an example, if the third low-side converter 6 of the third dc pole I210 is operated in an inverted manner, if the first locking mode of the inverter-side converter is adopted: a third low-end converter 6 of a third direct current pole I210 of the inverter station 200 trips a third low-end converter transformer incoming switch 232, the third low-end converter transformer incoming switch 232 enters a bypass pair after tripping, a third low-end valve set second bypass switch 62 is closed, and a first low-end converter 2 of a first direct current pole I110 of the rectifier station 100 controls a trigger angle to be 90 degrees; the first low side inverter 2 of the first dc pole I110 of the rectifying station 100 is put into the bypass pair, and the first low side bank of second bypass switches 22 is closed.
Taking the inverter station 200 as an example, if the third low-side converter 6 of the third dc pole I210 is operated in an inverted manner, if the inverter-side converter adopts the second locking mode: a third low-end converter 6 of the I210 pole of the inverter station 200 is put into a bypass pair, a second bypass switch 62 of a third low-end valve group is closed, a third low-end converter transformer incoming line switch 232 is opened, and a first low-end converter 2 of a first direct current pole I110 of the rectifier station 100 is controlled to have a trigger angle of 90 degrees; the first low side inverter 2 of the first dc pole I110 of the rectifying station 100 is put into the bypass pair, and the first low side bank of second bypass switches 22 is closed.
And in S120, controlling the direct current of the double direct current poles of the extra-high voltage direct current transmission system to be equal.
The control of the two-pole direct current equality is that the direct current passing through the inverter controlling the two-pole is the same direct current reference value. The direct current of the double direct current poles or the direct current of the converter is the high-voltage bus current, the low-voltage bus current or the pole bus current of the direct current side of the converter except the low-end converter with the fault.
And the direct current reference value is determined according to the active power, reactive power, fault current limitation or ground current limitation requirements of the extra-high voltage direct current transmission system.
If a fault occurs in the first low-side converter 2 of the first dc pole I110 of the rectifying station 100, the dc current of the first high-side converter 1 is controlled to be equal to the dc current of the converter of the second dc pole II120, and the third high-side converter 5 or the third low-side converter 6 of the third dc pole I210 of the inverting station 200 controls the dc voltage or controls the maximum firing angle.
If a fault occurs in the third low-side converter 6 of the third dc pole I210 of the inverter station 200, the fault information is transmitted to the rectifier station 100, the dc current of the first high-side converter 1 or the first low-side converter 2 of the first dc pole I110 of the rectifier station 100 is controlled to be equal to the dc current of the converter of the second dc pole II120, and the third high-side converter 5 of the third dc pole I210 of the inverter station 200 controls the dc voltage or controls the maximum firing angle.
In S130, the low-side inverter is isolated.
Taking the first low side converter 2 failure as an example, the first low side converter 2 is isolated, the first low side valve group first bypass switch 21 is closed, and the first low side valve group second bypass switch 22, the first low side valve group switch 23 and the first low side valve group bus switch 24 are separated.
A first low side group valve first bypass switch 21 is connected in parallel with the first low side converter 2, a first low side group valve second bypass switch 22 is connected to both ends of the first low side converter 2, a first low side group valve switch 23 is connected to the first low side converter 2 and the group valve connection line, and a first low side group bus switch 24 is connected to the first low side converter 2 and the polar neutral bus.
If the open current settings of the first low side bank second bypass switch 22, the first low side bank switch 23 and the first low side bank bus switch 24 are all less than the larger of the high voltage bus current IDC2P or the low voltage bus current IDC2N on the dc side of the first low side converter 2, then the low side converter 2 is isolated as follows.
First, if the high-voltage bus current IDC2P on the dc side of the first low-side converter 2 is greater than the low-voltage bus current IDC2N, the first low-side valve bank switch 23 is opened, the dc current of the dual dc poles is controlled to be zero, the first low-side valve bank second bypass switch 22 is opened again, the dc current of the dual dc poles is restored to a normal value, and then the first low-side valve bank bus switch 24 is opened.
Second, if the high-voltage bus current IDC2P on the dc side of the first low-side converter 2 is smaller than the low-voltage bus current IDC2N, the first low-side bank of bus switches 24 are opened, the dual dc current is controlled to be zero, the first low-side bank of second bypass switches 22 are opened again to recover the dual dc current, and then the first low-side bank of valve switches 23 are opened.
If the open current constant value of any one of the first low side valve group second bypass switch 22, the first low side valve group switch 23 and the first low side valve group bus switch 24 is larger than the larger value of the high voltage bus current IDC2P or the low voltage bus current IDC2N on the direct current side of the low side converter 2, the low side converter is isolated according to the following conditions.
If the breaking current constant value of the first low-side valve group second bypass switch 22 is the maximum and the high-voltage bus current IDC2P on the dc side of the first low-side converter 2 is greater than the low-voltage bus current IDC2N, the first low-side valve group switch 23 is first separated, then the first low-side valve group second bypass switch 22 is separated, and then the first low-side valve group bus switch 24 is separated.
If the breaking current constant value of the first low-side valve group second bypass switch 22 is the maximum and the high-voltage bus current IDC2P on the dc side of the first low-side converter 2 is smaller than the low-voltage bus current IDC2N, the first low-side valve group bus switch 24 is first separated, then the first low-side valve group second bypass switch 22 is separated, and then the first low-side valve group switch 23 is separated.
If the breaking current fixed value of the first low-end valve bank first valve bank switch 23 is the maximum, and the high-voltage bus current IDC2P on the direct current side of the first low-end converter 2 is greater than the low-voltage bus current IDC2N, the first low-end valve bank second bypass switch 22 is firstly separated, then the first low-end valve bank switch 23 is separated, and then the first low-end valve bank bus switch 24 is separated.
If the breaking current fixed value of the first low-side valve bank first valve bank switch 23 is the maximum and the high-voltage bus current IDC2P on the dc side of the first low-side converter 2 is smaller than the low-voltage bus current IDC2N, the first low-side valve bank bus switch 24 is firstly separated, then the first low-side valve bank switch 23 is separated, and then the first low-side valve bank second bypass switch 22 is separated.
If the breaking current fixed value of the first bus switch 24 of the first low-side valve bank is the largest, and the high-voltage bus current IDC2P on the dc side of the first low-side converter 2 is greater than the low-voltage bus current IDC2N, the first low-side valve bank switch 23 is first separated, then the first low-side valve bank bus switch 24 is separated, and then the first low-side valve bank second bypass switch 22 is separated.
If the breaking current fixed value of the first bus switch 24 of the first low-side valve bank is the largest, and the high-voltage bus current IDC2P on the dc side of the first low-side converter 2 is smaller than the low-voltage bus current IDC2N, the first low-side valve bank second bypass switch 22 is firstly separated, then the first low-side valve bank bus switch 24 is separated, and then the first low-side valve bank switch 23 is separated.
In S140, the converters other than the low-side converter continue to operate.
The remaining converters continue to operate as the first high-side converter 1 of the first dc pole I110, the second high-side converter 4 and the second low-side converter 3 of the second dc pole II120 of the rectifying station 100, and the inverting station 200 exits the third low-side converter 6 of the third dc pole I210, the third high-side converter 5 of the third dc pole I210, the fourth high-side converter 8 and the fourth low-side converter 7 of the fourth dc pole II220 to continue to operate.
In order to prevent other protection actions, under the condition, when the low-end converter detects that the valve area of the low-end converter has an earth fault, the fixed value of the range protection differential current of the direct current pole of the low-end converter is increased, or the range protection delay fixed value of the direct current pole of the low-end converter is increased or the range protection is shielded, the differential protection of the connecting lines of the shielding valve group is performed, and after the low-end converter is isolated, the range protection and the differential protection of the connecting lines of the valve group are opened.
The pole difference protection differential current is the difference between the sum of the pole neutral bus current, the direct current filter current, the pole neutral bus surge capacitor current and the pole neutral bus lightning arrester current and the pole bus current. The differential current of the valve group connecting wire is the difference between the low-voltage bus current at the DC side of the high-end converter and the high-voltage bus current at the DC side of the low-end converter.
If the rectifier station 100 operates in a bipolar ground return line, the ground pole line is grounded, that is, the metallic return line change-over switch 113 is in an on position, and the first low-end converter 2 fails, after the first low-end converter 2 is controlled to be locked, optionally, the metallic return line change-over switch 113 is pulled open to disconnect the normal connection between the converter station and the ground, and if the bipolar direct current poles operate in a balanced manner, no current flows through the fault point. If the inversion station 200 is configured with a metallic return transfer switch, the same method can be used to quickly isolate the fault current. After the first low-side inverter 2 is isolated, the metallic return line changeover switch 113 is turned on again.
The technical scheme that this embodiment provided, when the balanced operation of the two direct current poles of extra-high voltage direct current transmission system, the low end transverter place direct current is for full valve group operation and when detecting low end transverter valve zone earth fault, whole direct current pole does not block, but only the low end transverter of blocking the trouble, through bipolar balanced control, with the leading-in extremely utmost point busbar of trouble of electric current of normal operating, thereby avoid the extremely electric current of normal operating to flow into the fault point too much, guarantee more transverters operation simultaneously, avoid losing great direct current transmission power.
Fig. 3 is a schematic structural diagram of an extra-high voltage direct current low-side converter valve area ground fault control device 300 according to an embodiment of the present application, which includes a detection unit 310 and a control unit 320.
The detection unit 310 detects a high-voltage bus current IDC2P and a low-voltage bus current IDC2N of the low-side inverter, detects a bipolar pole-neutral bus current IDNC, detects a high-voltage bus current IDC1P, a low-voltage bus current IDC1N, or a pole bus current IDL of the high-side inverter, and detects a pole bus voltage UDL and a pole-neutral bus voltage UDN.
The control unit 320 determines that the extra-high voltage direct current transmission system operates in bipolar mode, the low-side converter operates in a full valve group, and when a ground fault is detected in a valve area of the low-side converter, the low-side converter is controlled to be locked, meanwhile, the bipolar direct current is controlled to be equal, the low-side converter is isolated, and the rest converters are controlled to continue to operate.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the description of the embodiments is only intended to facilitate the understanding of the methods and their core concepts of the present application. Meanwhile, a person skilled in the art should, according to the idea of the present application, change or modify the embodiments and applications of the present application based on the scope of the present application. In view of the above, the description should not be taken as limiting the application.
Claims (22)
1. An extra-high voltage direct current low-side converter valve area ground fault control method is applied to a low-side converter of a direct current pole of an extra-high voltage direct current transmission system, the extra-high voltage direct current transmission system comprises a double direct current pole, the direct current pole comprises at least two converters connected in series, the low-side converter is a converter close to a pole neutral bus, when the extra-high voltage direct current transmission system operates in the double direct current pole mode, the direct current pole where the low-side converter is located operates in a full valve group mode, and a ground fault of a valve area of the low-side converter is detected, the control method comprises the following steps:
controlling the low-side converter to be locked;
controlling the direct current of the double direct current poles of the extra-high voltage direct current transmission system to be equal;
isolating the low-side converter;
the converters other than the low side converter continue to operate.
2. The control method of claim 1, wherein the low side converter comprises at least one of a grid commutated converter or a voltage source converter.
3. The control method according to claim 2, wherein,
the dual DC pole operation comprises: each direct current pole is provided with at least one converter in operation;
the full valve bank operation comprises: and the direct current pole of the low-side converter is provided with at least one converter in operation besides the low-side converter.
4. The control method according to claim 1, wherein the occurrence of the ground fault in the valve area of the low-side converter includes:
and the low-side converter has at least one of a ground fault, a ground fault of a connecting line between the low-side converter and the converter transformer, and a ground fault of a valve side winding of the converter transformer.
5. The control method according to claim 1, wherein the detecting of the ground fault in the valve area of the low-side converter comprises:
and detecting that the absolute value of the difference between the high-voltage bus current and the low-voltage bus current on the direct current side of the low-side converter is greater than a set current difference value.
6. The control method of claim 1, wherein if the low side converter is a voltage source converter, said controlling the low side converter to latch comprises:
and controlling the low-side converter to stop triggering pulses, closing a second bypass switch of a low-side valve group where the low-side converter is located, and tripping off a converter transformer incoming line switch of the low-side converter, wherein the second bypass switch is connected with the anode and the cathode of the low-side converter.
7. The control method of claim 1, wherein if the low side converter is a grid commutated converter, said controlling the low side converter to latch comprises:
when the low-side converter operates in a rectifying mode, selecting a first locking mode of the rectifying side converter or a second locking mode of the rectifying side converter to control the low-side converter to be locked;
and when the low-side converter operates in an inverting mode, selecting a first locking mode of the inverting side converter or a second locking mode of the inverting side converter to control the low-side converter to be locked.
8. The control method according to claim 7, wherein the first blocking mode of the rectifier side converter comprises the following steps:
the low-end converter which controls the rectification operation stops sending trigger pulses, and the corresponding converter which controls the inversion operation has a trigger angle of 90 degrees;
and controlling to trip off a converter transformer incoming line switch of the low-side converter, closing a second bypass switch of the low-side converter, putting the corresponding inverter-operated converter into a bypass pair, and closing the bypass switch, wherein the second bypass switch is connected with the anode and the cathode of the low-side converter.
9. The control method according to claim 7, wherein the second blocking mode of the rectifier side converter comprises the following steps:
controlling the low-side converter to be put into a bypass pair, closing a second bypass switch, and simultaneously tripping on an incoming line switch of a converter transformer of the low-side converter, wherein a trigger angle of the corresponding inverter-operated converter is controlled to be 90 degrees, and the second bypass switch is connected with an anode and a cathode of the low-side converter;
and controlling the converter in the corresponding inversion operation to be put into the bypass pair, and closing the bypass switch.
10. The control method according to claim 7, wherein the first locking mode of the inverter-side converter comprises:
controlling a converter transformer incoming switch of the low-side converter in the tripping inversion operation to be put into a bypass pair, closing a second bypass switch, controlling a trigger angle of the corresponding converter in the rectification operation to be 90 degrees, and connecting the second bypass switch with the anode and the cathode of the low-side converter;
and controlling the converter which is in corresponding rectification operation to be put into a bypass pair, and closing a bypass switch.
11. The control method according to claim 7, wherein the second locking mode of the inverter-side converter comprises:
the low-side converter which controls the inversion operation is put into a bypass pair, a second bypass switch is closed, a converter transformer incoming line switch of the low-side converter is opened, a corresponding converter which rectifies the operation has a control trigger angle of 90 degrees, and the second bypass switch is connected with the anode and the cathode of the low-side converter;
and controlling the converter which is in corresponding rectification operation to be put into a bypass pair, and closing a bypass switch.
12. The control method according to claim 1, wherein the controlling the direct current of the double direct current poles of the extra-high voltage direct current transmission system to be equal comprises:
giving the same direct current reference value of the current converter with double direct current poles;
controlling high-voltage bus current or low-voltage bus current or pole bus current of converters other than the low-side converter to be the direct current reference value;
the direct current reference value is determined according to active power, reactive power, fault current limit or ground current limit requirements of the ultra-high voltage direct current transmission system;
if the faulted low-side converter operates in a rectifying mode, the converters on the rectifying side except the low-side converter adopt current control to control the direct current of the converters on the rectifying side except the low-side converter to be equal, and the converter on the inverting side operates in maximum trigger angle control or direct current voltage control;
if the low-side converter with the fault runs in an inverting mode, the converters on the inverting side except the low-side converter send fault information to the rectifying side, the rectifying side controls the direct currents of the converters with the double direct-current poles to be equal, or current control is adopted to control the direct currents of the converters on the inverting side except the low-side converter to be equal, and the converter on the rectifying side runs in direct-current voltage control.
13. The control method of claim 1, wherein said isolating said low side converter comprises:
the low-side switch is connected with the low-side converter in parallel, the second bypass switch is connected with two ends of the low-side converter, the valve group switch is connected with the low-side converter and the valve group connecting wire, and the bus switch is connected with the low-side converter and a polar neutral bus.
14. The control method according to claim 13, wherein if the divided current setting of the second bypass switch, the group switch and the bus switch is less than the larger of the high voltage bus current or the low voltage bus current on the dc side of the low side converter, the isolating the low side converter comprises:
if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the valve group switch is separated, the double-direct-current-pole direct current is controlled to be zero, the second bypass switch is separated again, the double-direct-current-pole direct current is recovered, and then the bus switch is separated;
and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the bus switch is separated, the double-direct-current-pole direct current is controlled to be zero, the second bypass switch is separated again, the double-direct-current-pole direct current is recovered, and then the valve group switch is separated.
15. The control method according to claim 13, wherein if the divided current constant value of any one of the second bypass switch, the group switch and the bus switch is larger than the larger value of the high voltage bus current or the low voltage bus current on the dc side of the low-side converter, and the divided current constant value of the second bypass switch is the largest, the dividing of the second bypass switch, the group switch and the bus switch of the low-side converter comprises:
if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the valve group switch is firstly separated, then the second bypass switch is separated, and then the bus switch is separated;
and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the bus switch is firstly separated, then the second bypass switch is separated, and then the valve group switch is separated.
16. The control method according to claim 13, wherein if the divided current constant value of any one of the second bypass switch, the group switch and the bus switch is larger than the larger value of the high voltage bus current or the low voltage bus current on the dc side of the low-side converter and the divided current constant value of the group switch is the largest, the dividing of the second bypass switch, the group switch and the bus switch of the low-side converter comprises:
if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the second bypass switch is firstly separated, then the valve group switch is separated, and then the bus switch is separated;
and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the bus switch is firstly separated, then the valve group switch is separated, and then the second bypass switch is separated.
17. The control method according to claim 13, wherein if the divided current constant value of any one of the second bypass switch, the group switch and the bus switch is larger than the larger value of the high voltage bus current or the low voltage bus current on the dc side of the low-side converter and the divided current constant value of the bus switch is the largest, the dividing of the second bypass switch, the group switch and the bus switch of the low-side converter comprises:
if the high-voltage bus current on the direct current side of the low-side converter is larger than the low-voltage bus current, the valve group switch is firstly separated, then the bus switch is separated, and then the second bypass switch is separated;
and if the high-voltage bus current on the direct current side of the low-side converter is smaller than the low-voltage bus current, the second bypass switch is firstly separated, then the bus switch is separated, and then the valve group switch is separated.
18. The control method of claim 1, wherein the converters other than the low side converter continue to operate, comprising:
and the current converters of the station where the low-end current converter is located except the low-end current converter continue to operate, other stations quit the current converters corresponding to the low-end current converter, and the rest current converters continue to operate.
19. The control method of claim 1, further comprising, prior to said isolating said low side converter:
and increasing the pole difference protection differential current constant value of the direct current pole of the low-end converter, or increasing the pole difference protection delay constant value of the direct current pole of the low-end converter or shielding the pole difference protection until the low-end converter is isolated.
20. The control method according to claim 1, wherein after said controlling said low side inverter to be locked, further comprising:
and pulling a metal return line change-over switch or a neutral bus grounding switch to disconnect the connection between the converter station and the ground, wherein the metal return line change-over switch is connected with the bipolar neutral bus and the grounding electrode circuit, and the neutral bus grounding switch is connected with the bipolar neutral bus and the grounding network in the station.
21. The control method of claim 20, wherein if the metallic return line transfer switch or neutral bus grounding switch within a station is pulled, the control method further comprises:
and after the low-side converter is isolated, closing the metal return wire change-over switch or the neutral bus grounding switch.
22. An extra-high voltage dc low side converter valve area ground fault control apparatus applying the extra-high voltage dc low side converter valve area ground fault control method according to any one of claims 1 to 21, the control apparatus comprising:
a detection unit for detecting a high-voltage bus current and a low-voltage bus current of the low-side converter, detecting a polar neutral bus current, detecting a high-voltage bus current, a low-voltage bus current or a polar bus current of a converter other than the low-side converter, which is located at a pole of the low-side converter, and detecting a polar bus voltage and a polar neutral bus voltage;
and the control unit is used for judging that the extra-high voltage direct current transmission system operates on double direct current poles, controlling the low-end converter to be locked when the direct current pole where the low-end converter is located operates on a full valve group and detecting that the valve area of the low-end converter has a ground fault, controlling the direct current of the double direct current poles to be equal, isolating the low-end converter and controlling the converters except the low-end converter to continue to operate.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911368626.7A CN110970879B (en) | 2019-12-26 | 2019-12-26 | Method and device for controlling valve area ground fault of extra-high voltage direct current low-side converter |
| PCT/CN2020/139576 WO2021129828A1 (en) | 2019-12-26 | 2020-12-25 | Earth fault control method for valve region of ultra-high-voltage direct current low-voltage-end converter, and control device |
| BR112022010341-7A BR112022010341B1 (en) | 2019-12-26 | 2020-12-25 | METHOD AND DEVICE FOR CONTROLING GROUND FAULT IN THE VALVE AREA OF THE UHVDC BOTTOM END CONVERTER |
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|---|---|---|---|
| CN201911368626.7A CN110970879B (en) | 2019-12-26 | 2019-12-26 | Method and device for controlling valve area ground fault of extra-high voltage direct current low-side converter |
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| CN110970879A true CN110970879A (en) | 2020-04-07 |
| CN110970879B CN110970879B (en) | 2021-10-01 |
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| CN201911368626.7A Active CN110970879B (en) | 2019-12-26 | 2019-12-26 | Method and device for controlling valve area ground fault of extra-high voltage direct current low-side converter |
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| Country | Link |
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| CN (1) | CN110970879B (en) |
| BR (1) | BR112022010341B1 (en) |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111541259A (en) * | 2020-04-23 | 2020-08-14 | 南方电网科学研究院有限责任公司 | Charging control method, device and medium for hybrid multi-terminal direct current transmission system |
| CN111697610A (en) * | 2020-05-19 | 2020-09-22 | 南方电网科学研究院有限责任公司 | Bipolar balance control method, device and medium for three-terminal direct-current power transmission system |
| WO2021129828A1 (en) * | 2019-12-26 | 2021-07-01 | 南京南瑞继保电气有限公司 | Earth fault control method for valve region of ultra-high-voltage direct current low-voltage-end converter, and control device |
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| WO2022078527A1 (en) * | 2020-10-15 | 2022-04-21 | 许继电气股份有限公司 | Transient voltage control method and apparatus for ultra-high-voltage hybrid direct-current power transmission system |
| CN113471918A (en) * | 2021-06-28 | 2021-10-01 | 南京南瑞继保电气有限公司 | Ice melting circuit of extra-high voltage direct current transmission system and control method and control device thereof |
| CN113471918B (en) * | 2021-06-28 | 2022-12-13 | 南京南瑞继保电气有限公司 | Ice melting circuit of extra-high voltage direct-current transmission system and control method and control device thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2021129828A1 (en) | 2021-07-01 |
| CN110970879B (en) | 2021-10-01 |
| BR112022010341B1 (en) | 2023-09-26 |
| BR112022010341A2 (en) | 2022-08-16 |
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