CN111030065A - Fault protection area setting method for multi-terminal offshore direct current wind power plant system - Google Patents
Fault protection area setting method for multi-terminal offshore direct current wind power plant system Download PDFInfo
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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
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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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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention provides a method for setting fault protection areas of a multi-end offshore direct current wind power station system, and provides protection objects and protection measures of each protection area, wherein the method comprises the following steps: according to the framework of the multi-terminal offshore direct current wind power plant system, the multi-terminal offshore direct current wind power plant system is set to six protection areas: the protection area comprises a wind power plant protection area, a first boosting protection area, a second boosting protection area, a direct current protection area, a converter station protection area and an alternating current system protection area. According to the method for setting the fault protection area of the multi-terminal offshore direct current wind power plant system, the multi-terminal offshore direct current wind power plant system with a large coverage area is set to be different protection areas for protection, so that the fault protection effect of the multi-terminal offshore direct current wind power plant system is improved, and the fault protection scheme configuration of the multi-terminal offshore direct current wind power plant system is facilitated.
Description
Technical Field
The invention belongs to the technical field of electric power, and particularly relates to a method for setting a fault protection area of a multi-terminal offshore direct current wind power plant system.
Background
With the proposal of policies such as energy internet and clean energy, China focuses on the research and development work of efficient and clean electric energy, wherein the wind power generation technology is mature, but the research objects mainly focus on onshore wind power. With the continuous increase of wind power capacity, onshore wind power is limited, and offshore wind power is developed and researched. Compared with onshore wind power, offshore wind power has the advantages of richer wind power resources, more stable wind speed and wind direction, high power generation utilization time, no occupation of land resources and suitability for large-scale development.
The scheme for accessing the offshore wind farm to the large power grid mainly comprises an alternating current access scheme and a direct current access scheme. The alternating current access scheme is influenced by charging current, and is commonly used in wind power plant grid-connected occasions with short offshore distance and small transmission power, and the direct current grid-connected scheme is more suitable for occasions with offshore wind power plant distance of more than 80 km. In the existing direct current grid-connected scheme, a Voltage Source Converter (VSC) -based high-voltage direct current transmission technology has the advantages of long transmission distance, no need of additionally arranging a filter device and the like, and becomes a preferred scheme for grid connection of an offshore far-distance offshore wind power plant.
With the increase of installed capacity and transmission distance of an offshore wind farm, the application of a high-voltage direct-current transmission technology in offshore wind power grid connection is more and more extensive, a full-direct-current offshore wind farm system adopting direct current for wind farm energy collection and transmission represents the long-term development trend of offshore wind power, but due to the fact that the offshore climate environment is quite severe, different types of electrical operation faults can easily occur in the operation process of the offshore direct-current wind farm system, so that the normal operation of the offshore direct-current wind farm system is seriously affected, the normal power consumption of a user is further affected, and greater economic loss is caused.
Disclosure of Invention
The invention provides a method for setting a fault protection area of a multi-terminal offshore direct current wind power plant system, which is used for reliably protecting the multi-terminal offshore direct current wind power plant system, reducing the fault loss of the multi-terminal offshore direct current wind power plant system and ensuring the safe operation of the multi-terminal offshore direct current wind power plant system.
In the method for setting the fault protection zone of the multi-terminal offshore direct current wind power plant system, the multi-terminal offshore direct current wind power plant system comprises a wind power generation unit, an alternating current-direct current converter, a direct current transformer or/and a direct current transformer combination consisting of the direct current transformer, an offshore converter station, a onshore converter station, an onshore transformer and an alternating current power grid,
wherein the content of the first and second substances,
the wind power generation unit, the alternating current-direct current converter, the direct current transformer or/and a direct current transformer combination formed by the direct current transformer and the offshore converter station are sequentially connected;
the land converter station, the land transformer and the alternating current power grid are connected in sequence;
the offshore converter stations are one or more stations, when the offshore converter stations are multiple stations, the offshore converter stations from a first station to a last station are sequentially connected in series, two adjacent offshore converter stations are connected through two direct current circuit breakers through direct current cables, and the offshore converter stations of the first station and the last station are connected to the onshore converter station through the two direct current circuit breakers through the direct current cables; when the offshore converter station is a station, the offshore converter station is connected to the onshore converter station through a direct current cable and two direct current breakers,
the fault protection area setting method comprises the following steps:
according to the architecture of the multi-terminal offshore direct current wind power plant system, the multi-terminal offshore direct current wind power plant system is set into a wind power plant protection area, a first boost protection area, a second boost protection area, a direct current protection area, a converter station protection area and an alternating current system protection area,
wherein the content of the first and second substances,
the wind power plant protection area comprises the wind power generation units and corresponding alternating current-direct current converters which are connected with each other;
the first boost protection area comprises the direct current transformer or/and a direct current transformer combination formed by the direct current transformer;
the second boost protection zone comprises the offshore converter station;
when the offshore converter station is a single station, the direct current protection zone comprises direct current cables and direct current circuit breakers between the offshore converter station and the onshore converter station, and when the offshore converter station is a multi-station, the direct current protection zone comprises direct current cables and direct current circuit breakers between adjacent offshore converter stations, and also comprises direct current cables and two direct current circuit breakers between the first station and the last offshore converter station and the onshore converter station;
the converter station protection zone comprises the onshore converter station;
the ac system protection area includes the land transformer and an ac power grid.
Further, the method for setting the fault protection area of the multi-terminal offshore direct current wind power plant system further comprises the following steps:
dividing the faults of the multi-end offshore direct current wind power plant system into the following parts according to the protection area structure and equipment composition of the multi-end offshore direct current wind power plant system: a fault of a protection area of a wind power plant, a fault of a first boosting protection area, a fault of a second boosting protection area, a fault of a direct current protection area, a fault of a protection area of a converter station and a fault of a protection area of an alternating current system;
and respectively determining objects to be protected according to the failure of the wind power plant protection area, the failure of the first boost protection area, the failure of the second boost protection area, the failure of the direct-current protection area, the failure of the converter station protection area and the failure of the alternating-current system protection area, and taking corresponding protection measures.
Furthermore, in the wind power plant protection area, the wind power generation unit is composed of one or more wind power generators connected in series or in parallel, the wind power generators and the AC/DC converter are connected with a second DC cable, a circuit breaker is arranged in the second DC cable,
the failure of the wind power plant protection area is a failure of a wind driven generator and a failure of a second direct current cable,
the protection measures taken for the faults of the wind power plant protection area are wind driven generator protection, namely fan protection and second direct current cable protection,
wherein the content of the first and second substances,
the fan protection is to adopt over-current protection, over-voltage protection and short-circuit protection to the fan;
the main protection of the second direct current cable protection is to adopt differential protection for the second direct current cable and equip the second direct current cable with undervoltage protection, overcurrent protection, overvoltage protection, distance protection and breaker failure protection.
Further, the first boost protection zone fault is a direct current transformer fault,
the protection measures taken for the fault of the direct current transformer are to configure the direct current transformer with: overcurrent protection; overvoltage protection; short-circuit protection; current differential protection; monitoring the state of each submodule in the direct current transformer; the valve cooling system of the DC transformer protects.
Further, the offshore converter station comprises a high voltage direct current transformer,
the second boosting protection area fault is a high-voltage direct-current transformer fault,
the protection measures taken for the fault of the high-voltage direct-current transformer are that the high-voltage direct-current transformer is configured with: overcurrent protection; overvoltage protection; short-circuit protection; current differential protection; monitoring the state of each submodule in the high-voltage direct-current transformer; and the valve cooling system of the high-voltage direct-current transformer is protected.
Further, in the direct current protection zone, the offshore converter station comprises a high voltage direct current transformer, the high voltage direct current transformer is provided with a direct current bus, a breaker is arranged in the direct current bus,
the direct current protection zone faults comprise direct current bus faults and direct current cable faults, namely direct current line faults,
the protection measures taken for the fault of the direct current protection area are direct current bus protection and direct current line protection,
wherein the content of the first and second substances,
the direct current bus protection is to adopt differential protection for the direct current bus and configure overcurrent protection, overvoltage protection, undervoltage protection and breaker failure protection for the direct current bus;
the direct current line protection adopts differential protection as main protection for the direct current line, and the direct current line is provided with undervoltage protection, overcurrent protection, overvoltage protection, distance protection and breaker failure protection.
Further, the onshore converter station comprises a converter,
the converter station protection zone fault is a converter fault,
the protection measures taken for the converter fault are to configure the converter with: overcurrent protection of the converter; overvoltage protection of the current converter; valve short circuit protection in the converter; valve current differential protection in the converter; monitoring the state of each submodule in the converter; valve cooling system protection in the converter.
Further, in the alternating current system protection area, the land transformer is provided with an alternating current bus, and the land transformer is connected with a bridge arm reactor,
the alternating current system protection zone faults comprise onshore transformer faults, alternating current bus faults and bridge arm reactor faults,
the protection measures adopted for the faults of the protection area of the alternating current system are the protection of a land transformer, the protection of an alternating current bus and the protection of a bridge arm reactor,
wherein the content of the first and second substances,
the onshore transformer protection is to configure non-electric quantity protection and electric quantity protection for the onshore transformer;
the alternating current bus protection is that differential protection is adopted for the alternating current bus as main protection, and overcurrent protection with time limit is configured for the alternating current bus as backup protection;
the bridge arm reactor protection is to configure differential protection and overcurrent protection for the bridge arm reactor.
Further, the protection of the onshore transformer is the over-current protection, the zero-sequence voltage protection and the zero-sequence current protection of the onshore transformer configuration transformer.
The method for setting the fault protection area of the multi-terminal offshore direct current wind power plant system can provide effective protection for the multi-terminal offshore direct current wind power plant system, thereby ensuring the safe operation of the multi-terminal offshore direct current wind power plant system and the normal power consumption of users and avoiding economic loss. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 shows a configuration diagram of a fault protection zone of a multi-terminal offshore direct current wind farm system according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be 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 some, but not all, embodiments of the present invention. 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 invention.
In the present application, the plurality refers to more than one, and similarly, the plurality and the plurality refer to more than one and more than one, respectively.
The invention provides a method for setting a fault protection area of a multi-terminal offshore direct current wind power plant system, and fig. 1 shows a structure diagram for setting the fault protection area of the multi-terminal offshore direct current wind power plant system. In fig. 1, 1 is a wind power generation unit, 2 is an ac/dc converter, 3 is a medium voltage dc transformer, 4 is a high voltage dc transformer, and 5 is a modular multilevel converter.
As can be seen from fig. 1, the multi-terminal offshore dc wind farm system includes a wind power generation unit, an ac/dc converter, a dc transformer or/and a dc transformer combination comprising the dc transformer, an offshore converter station, an onshore transformer, and an ac grid.
Each wind power generation unit 1 is composed of one or more wind power generation sets connected in series or in parallel, each wind power generation unit 1 is connected to a corresponding alternating current-direct current converter 2, and the alternating current-direct current converters 2 are connected with corresponding medium-voltage direct current transformers 3 through direct current cables. The number of the wind power generation units 1 may be one or more, and thus, one or more medium voltage dc transformers 3 are correspondingly connected to the wind power generation units 1. When there are multiple medium voltage dc transformers 3, some or all of the medium voltage dc transformers 3 in the multiple medium voltage dc transformers 3 constitute one or more medium voltage dc transformer combinations IPOS with input connected in parallel and output connected in series. In the medium-voltage direct-current transformer combination IPOS, a first medium-voltage direct-current transformer 3 to a last medium-voltage direct-current transformer 3 are sequentially connected in series through direct-current cables, and the head and the tail of the two medium-voltage direct-current transformers 3 are connected to an offshore converter station through a medium-voltage direct-current cable MVDC and a direct-current breaker DCCB.
The number of the medium-voltage direct-current transformer combinations IPOS or/and the medium-voltage direct-current transformers 3 which are connected to the same offshore converter station through the medium-voltage direct-current cables MVDC can be multiple or one, wherein when the number of the medium-voltage direct-current transformer combinations IPOS is one, the medium-voltage direct-current transformer combinations IPOS is directly connected to the offshore converter station through the medium-voltage direct-current cables MVDC through the direct-current circuit breakers DCCB; when a plurality of medium voltage direct current transformer combinations IPOS are provided, all medium voltage direct current cables MVDC connected with all the medium voltage direct current transformer combinations IPOS are converged to one medium voltage direct current cable MVDC through a direct current breaker DCCB and then are connected to the offshore converter station through one direct current breaker DCCB.
When one wind power generation unit 1 is provided, one corresponding medium-voltage direct-current transformer 3 is provided, and the medium-voltage direct-current transformer 3 is directly connected to the offshore converter station through a medium-voltage direct-current cable MVDC via a direct-current breaker DCCB. When the number of the medium-voltage direct-current transformers 3 is multiple but not all of the medium-voltage direct-current transformer combinations IPOS and the number of the medium-voltage direct-current transformers 3 which do not form the medium-voltage direct-current transformer combinations IPOS is one, the direct-current cable connected with the medium-voltage direct-current transformers 3 is connected to the offshore converter station through a direct-current breaker; when the number of the medium-voltage direct-current transformers 3 is multiple but not all of the medium-voltage direct-current transformer combinations IPOS, and when the number of the medium-voltage direct-current transformers 3 not forming the medium-voltage direct-current transformer combinations IPOS is multiple, the medium-voltage direct-current transformers 3 are respectively connected to the offshore converter station through a direct-current breaker by respective connected direct-current cables.
The offshore converter station is composed of one or more high-voltage direct-current transformers connected in series or in parallel. The offshore converter station can be one place or a plurality of places. When the number of the medium voltage direct current transformers 3 or/and the medium voltage direct current transformer combinations IPOS is multiple, the medium voltage direct current transformers 3 or/and the medium voltage direct current transformer combinations IPOS are respectively connected to the same or different offshore converter stations, as can be seen from fig. 1, the different medium voltage direct current transformer combinations IPOS are respectively connected to the offshore converter station 1 and the offshore converter station 2.
When the offshore converter stations are multiple stations, the first offshore converter station and the last offshore converter station are sequentially connected in series, two adjacent offshore converter stations are connected through direct current cables and two direct current circuit breakers DCCB, the first offshore converter station and the last offshore converter station are connected to the onshore converter station through high voltage direct current cables HVDC and two direct current circuit breakers DCCB, and the multiple offshore converter stations and the onshore converter station form an annular direct current power grid. When the offshore converter station is a station, the offshore converter station is connected to the onshore converter station through the high-voltage direct current cable HVDC through the two direct current circuit breakers DCCB. The offshore converter station is composed of one or more high-voltage direct-current transformers 4 connected in series or in parallel.
The onshore converter station is connected to the ac power grid via an onshore transformer.
The direct current circuit breakers DCCB are used for providing fault isolation and fault protection for the offshore direct current wind power plant system; the direct current transformer of the offshore direct current wind power plant system needs to meet the following technical requirements: high voltage, high capacity, high voltage gain, high reliability, fault isolation, redundant operation, etc., wherein the medium voltage dc transformer 3 is preferably a dual active full bridge (DAB) type dc transformer, and the high voltage dc transformer 4 is preferably an isolated Modular Multilevel Converter (MMC) type dc transformer. The medium-voltage direct-current transformer combined IPOS is preferably of a multiple modular structure which takes a DAB type direct-current transformer as a basic unit for input and output series-parallel connection.
As shown in fig. 1, in the method for setting the fault protection area of the multi-terminal offshore direct current wind farm system according to the present invention, the multi-terminal offshore direct current wind farm system is set as the following areas: the system comprises a wind power plant protection area, a first boosting protection area, a second boosting protection area, a direct current protection area, a converter station protection area and an alternating current system protection area.
Wherein the content of the first and second substances,
the wind power plant protection area comprises a wind power generation unit 1 and an alternating current-direct current converter 2;
the first boost protection area comprises a medium-voltage direct-current transformer 3, when the medium-voltage direct-current transformer 3 forms a medium-voltage direct-current transformer combination IPOS, the first boost protection area further comprises the medium-voltage direct-current transformer combination IPOS, and when the medium-voltage direct-current transformer combination IPOS is multiple, the first boost protection area further comprises medium-voltage direct-current cables MVDC connected with the medium-voltage direct-current transformer combinations IPOS and direct-current circuit breakers DCCB respectively connected with the medium-voltage direct-current cables MVDC;
the second boost protection zone comprises an offshore converter station and a direct current breaker DCCB between the offshore converter station and the first boost protection zone;
when the offshore converter station is a single station, the direct current protection zone comprises a high-voltage direct current cable HVDC and a direct current breaker DCCB between the offshore converter station and a land converter station, when the offshore converter station is a multi-station, the direct current protection zone comprises a direct current cable and a direct current breaker DCCB between adjacent offshore converter stations, and further comprises a high-voltage direct current cable HVDC and two direct current breakers DCCB between the first station and the last station offshore converter station and the land converter station;
the converter station protection zone comprises a land converter station;
the AC system protection area includes an onshore transformer and an AC power grid.
Dividing the faults of the multi-end offshore direct current wind power plant system into the following parts according to the structure and equipment composition of the multi-end offshore direct current wind power plant system: a fault of a protection area of a wind power plant, a fault of a first boosting protection area, a fault of a second boosting protection area, a fault of a direct current protection area, a fault of a protection area of a converter station and a fault of a protection area of an alternating current system;
determining objects to be protected respectively aiming at the wind power plant protection area fault, the first boosting protection area fault, the second boosting protection area fault, the direct current protection area fault, the converter station protection area fault and the alternating current system protection area fault, and taking corresponding protection measures as follows:
(1) wind farm protection zone
In the wind power plant protection area, the wind driven generator and the alternating current-direct current converter are connected with a second direct current cable, and a circuit breaker is arranged in the second direct current cable.
The wind power plant protection area faults are wind driven generator faults and second direct current cable faults, and therefore protection measures adopted for the wind power plant protection area faults mainly comprise wind driven generator protection and second direct current cable protection. The protection of the wind driven generator mainly adopts overcurrent protection, overvoltage protection, short circuit protection and the like for the wind driven generator; in the second direct-current cable protection, differential protection is adopted as main protection for the second direct-current cable, and undervoltage protection, overcurrent protection, overvoltage protection, distance protection and breaker failure protection are provided for the second direct-current cable.
(2) First boost protection zone
The main protection object of the first boost protection area is a medium-voltage direct-current transformer, and therefore the fault of the first boost protection area is a fault of the medium-voltage direct-current transformer.
The protection measures taken for the faults of the medium-voltage direct-current transformer are to configure the medium-voltage direct-current transformer with: overcurrent protection of the medium-voltage direct-current transformer; overvoltage protection of the medium-voltage direct-current transformer; short-circuit protection of the medium-voltage direct-current transformer; current differential protection of a medium-voltage direct-current transformer; monitoring the state of each submodule in the medium-voltage direct-current transformer; protection of a valve cooling system in the medium-voltage direct-current transformer, and the like.
(3) Second boost protection zone
The main protection object of the second boost protection area is a high-voltage direct-current transformer in the offshore converter station, so that the fault of the second boost protection area is the fault of the high-voltage direct-current transformer.
The protection measures taken for the fault of the high-voltage direct-current transformer are that the high-voltage direct-current transformer is configured with: overcurrent protection of the high-voltage direct-current transformer; overvoltage protection of the high-voltage direct-current transformer; short-circuit protection of the high-voltage direct-current transformer; current differential protection of the high-voltage direct-current transformer; monitoring the state of each submodule in the high-voltage direct-current transformer; protection of a valve cooling system in the high-voltage direct-current transformer and the like.
(4) DC protection zone
The direct current protection zone comprises a direct current bus (namely, a direct current bus of a high voltage direct current transformer) and a direct current line (namely, a direct current cable between the offshore converter station and a high voltage direct current cable between the offshore converter station and the onshore converter station) related to the offshore converter station. And the direct current bus and the direct current line are provided with circuit breakers.
The direct current protection area faults comprise direct current bus faults and direct current line faults, and therefore the protection measures adopted for the direct current protection area faults are direct current bus protection and direct current line protection. The direct current bus protection is to adopt differential protection for the direct current bus and configure overcurrent protection, overvoltage protection, undervoltage protection and breaker failure protection for the direct current bus; the direct current line protection is to adopt differential protection as main protection for the direct current line and equip the direct current line with undervoltage protection, overcurrent protection, overvoltage protection, distance protection and breaker failure protection.
(5) Converter station protection zone
The main protection object of the converter station protection zone is a converter, such as a modular multilevel converter, and therefore the converter station protection zone fault is a converter fault.
The protection measures taken for the converter faults are the configuration of the converter: overcurrent protection of the converter; overvoltage protection of the current converter; valve short circuit protection in the converter; valve current differential protection in the converter; monitoring the state of each submodule in the converter; valve cooling system protection in the converter.
(6) Protection area of AC system
In the ac system protection area, the land transformer (preferably, a coupling transformer) is provided with an ac bus, and the land transformer is connected with a bridge arm reactor. The alternating current system protection area faults mainly comprise onshore transformer faults, alternating current bus faults and bridge arm reactor faults. Therefore, the main protection objects in the ac system protection area are the land transformer, the ac bus, and the bridge arm reactor.
The protection measures adopted for the faults of the protection area of the alternating current system are protection of a land transformer, protection of an alternating current bus and protection of a bridge arm reactor. The specific protection configuration is as follows:
the protection of the onshore transformer is to configure two categories of non-electric quantity protection and electric quantity protection for the onshore transformer, and mainly configure overcurrent protection, zero-sequence voltage protection and zero-sequence current protection of the transformer.
The alternating current bus protection is that differential protection is adopted for the alternating current bus as main protection, and overcurrent protection with time limit is configured for the alternating current bus as backup protection;
the bridge arm reactor protection is to configure differential protection and overcurrent protection for the bridge arm reactor.
In engineering applications, when configuring protection in different protection zones, the configuration of the protection function must determine that the protection function can reflect all faults in all operating modes. And when the measurement system is configured, the measurement points selected by the protection of different protection zones should be mutually overlapped to ensure that the protected system has no dead zone.
According to the method for setting the fault protection area of the multi-terminal offshore direct current wind power plant system, the multi-terminal offshore direct current wind power plant system with a large coverage area is set to be different protection areas, the objects to be protected are respectively determined and corresponding protection measures are taken, so that the fault protection effect of the multi-terminal offshore direct current wind power plant system is improved, the multi-terminal offshore direct current wind power plant system is conveniently managed, and the multi-terminal offshore direct current wind power plant system can be flexibly adapted to the multi-terminal offshore direct current wind power plants with different topological structures.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (9)
1. A method for setting a fault protection area of a multi-terminal offshore direct current wind power plant system is characterized in that the multi-terminal offshore direct current wind power plant system comprises a wind power generation unit, an alternating current-direct current converter, a direct current transformer or/and a direct current transformer combination formed by the direct current transformer, an offshore converter station, a land transformer and an alternating current power grid,
wherein the content of the first and second substances,
the wind power generation unit, the alternating current-direct current converter, the direct current transformer or/and a direct current transformer combination formed by the direct current transformer and the offshore converter station are sequentially connected;
the land converter station, the land transformer and the alternating current power grid are connected in sequence;
the offshore converter stations are one or more stations, when the offshore converter stations are multiple stations, the offshore converter stations from a first station to a last station are sequentially connected in series, two adjacent offshore converter stations are connected through two direct current circuit breakers through direct current cables, and the offshore converter stations of the first station and the last station are connected to the onshore converter station through the two direct current circuit breakers through the direct current cables; when the offshore converter station is a station, the offshore converter station is connected to the onshore converter station through a direct current cable and two direct current breakers,
the fault protection area setting method comprises the following steps:
according to the architecture of the multi-terminal offshore direct current wind power plant system, the multi-terminal offshore direct current wind power plant system is set into a wind power plant protection area, a first boost protection area, a second boost protection area, a direct current protection area, a converter station protection area and an alternating current system protection area,
wherein the content of the first and second substances,
the wind power plant protection area comprises the wind power generation units and corresponding alternating current-direct current converters which are connected with each other;
the first boost protection area comprises the direct current transformer or/and a direct current transformer combination formed by the direct current transformer;
the second boost protection zone comprises the offshore converter station;
when the offshore converter station is a single station, the direct current protection zone comprises direct current cables and direct current circuit breakers between the offshore converter station and the onshore converter station, and when the offshore converter station is a multi-station, the direct current protection zone comprises direct current cables and direct current circuit breakers between adjacent offshore converter stations, and also comprises direct current cables and two direct current circuit breakers between the first station and the last offshore converter station and the onshore converter station;
the converter station protection zone comprises the onshore converter station;
the ac system protection area includes the land transformer and an ac power grid.
2. The method for setting the fault protection zone of the multi-terminal offshore direct current wind farm system according to claim 1,
further comprising:
dividing the faults of the multi-end offshore direct current wind power plant system into the following parts according to the protection area structure and equipment composition of the multi-end offshore direct current wind power plant system: a fault of a protection area of a wind power plant, a fault of a first boosting protection area, a fault of a second boosting protection area, a fault of a direct current protection area, a fault of a protection area of a converter station and a fault of a protection area of an alternating current system;
and respectively determining objects to be protected according to the failure of the wind power plant protection area, the failure of the first boost protection area, the failure of the second boost protection area, the failure of the direct-current protection area, the failure of the converter station protection area and the failure of the alternating-current system protection area, and taking corresponding protection measures.
3. The method for setting the fault protection zone of the multi-terminal offshore direct current wind farm system according to claim 2,
in the wind power plant protection area, the wind power generation unit is composed of one or more wind power generators connected in series or in parallel, the wind power generators and the AC-DC converter are connected with a second DC cable, a circuit breaker is arranged in the second DC cable,
the failure of the wind power plant protection area is a failure of a wind driven generator and a failure of a second direct current cable,
the protection measures taken for the faults of the wind power plant protection area are wind driven generator protection, namely fan protection and second direct current cable protection,
wherein the content of the first and second substances,
the fan protection is to adopt over-current protection, over-voltage protection and short-circuit protection to the fan;
the main protection of the second direct current cable protection is to adopt differential protection for the second direct current cable and equip the second direct current cable with undervoltage protection, overcurrent protection, overvoltage protection, distance protection and breaker failure protection.
4. The method for setting the fault protection zone of the multi-terminal offshore direct current wind farm system according to claim 2,
the first boost protection zone fault is a direct current transformer fault,
the protection measures taken for the fault of the direct current transformer are to configure the direct current transformer with: overcurrent protection; overvoltage protection; short-circuit protection; current differential protection; monitoring the state of each submodule in the direct current transformer; the valve cooling system of the DC transformer protects.
5. The method for setting the fault protection zone of the multi-terminal offshore direct current wind farm system according to claim 2,
the offshore converter station comprises a high voltage direct current transformer,
the second boosting protection area fault is a high-voltage direct-current transformer fault,
the protection measures taken for the fault of the high-voltage direct-current transformer are that the high-voltage direct-current transformer is configured with: overcurrent protection; overvoltage protection; short-circuit protection; current differential protection; monitoring the state of each submodule in the high-voltage direct-current transformer; and the valve cooling system of the high-voltage direct-current transformer is protected.
6. The method for setting the fault protection zone of the multi-terminal offshore direct current wind farm system according to claim 2,
in the direct current protection area, the offshore converter station comprises a high-voltage direct current transformer, the high-voltage direct current transformer is provided with a direct current bus, a breaker is arranged in the direct current bus,
the direct current protection zone faults comprise direct current bus faults and direct current cable faults, namely direct current line faults,
the protection measures taken for the fault of the direct current protection area are direct current bus protection and direct current line protection,
wherein the content of the first and second substances,
the direct current bus protection is to adopt differential protection for the direct current bus and configure overcurrent protection, overvoltage protection, undervoltage protection and breaker failure protection for the direct current bus;
the direct current line protection adopts differential protection as main protection for the direct current line, and the direct current line is provided with undervoltage protection, overcurrent protection, overvoltage protection, distance protection and breaker failure protection.
7. Method for setting a fault protection zone of a multi-terminal offshore direct current wind farm system according to any of the claims 2 to 6,
the onshore converter station comprises a converter,
the converter station protection zone fault is a converter fault,
the protection measures taken for the converter fault are to configure the converter with: overcurrent protection of the converter; overvoltage protection of the current converter; valve short circuit protection in the converter; valve current differential protection in the converter; monitoring the state of each submodule in the converter; valve cooling system protection in the converter.
8. Method for setting a fault protection zone of a multi-terminal offshore direct current wind farm system according to any of the claims 2 to 6,
in the alternating current system protection area, the land transformer is provided with an alternating current bus and is connected with a bridge arm reactor,
the alternating current system protection zone faults comprise onshore transformer faults, alternating current bus faults and bridge arm reactor faults,
the protection measures adopted for the faults of the protection area of the alternating current system are the protection of a land transformer, the protection of an alternating current bus and the protection of a bridge arm reactor,
wherein the content of the first and second substances,
the onshore transformer protection is to configure non-electric quantity protection and electric quantity protection for the onshore transformer;
the alternating current bus protection is that differential protection is adopted for the alternating current bus as main protection, and overcurrent protection with time limit is configured for the alternating current bus as backup protection;
the bridge arm reactor protection is to configure differential protection and overcurrent protection for the bridge arm reactor.
9. The method for setting the fault protection zone of the multi-terminal offshore direct current wind farm system according to claim 8,
the protection of the onshore transformer is to configure the overcurrent protection, the zero-sequence voltage protection and the zero-sequence current protection of the transformer for the onshore transformer.
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