CN111864703B - Device and method for realizing direct-current networking of ship electric propulsion system - Google Patents
Device and method for realizing direct-current networking of ship electric propulsion system Download PDFInfo
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- CN111864703B CN111864703B CN201910359967.1A CN201910359967A CN111864703B CN 111864703 B CN111864703 B CN 111864703B CN 201910359967 A CN201910359967 A CN 201910359967A CN 111864703 B CN111864703 B CN 111864703B
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H21/00—Use of propulsion power plant or units on vessels
- B63H21/12—Use of propulsion power plant or units on vessels the vessels being motor-driven
- B63H21/17—Use of propulsion power plant or units on vessels the vessels being motor-driven by electric motor
Abstract
The invention discloses a device and a method for realizing direct-current networking of a ship electric propulsion system, wherein a differential protection principle is applied to a direct-current networking as main protection of direct-current busbar short circuit, and an alternating-current circuit breaker at the front end of a rectifier is used as instantaneous protection in the main protection of busbar short circuit, so that the whole ship direct-current networking is only provided with the direct-current circuit breaker at a busbar switch and is switched off when the corresponding busbar is short-circuited. In addition, a direct current fuse at the front end of the inverter is used as short-time delay protection in the direct current busbar short circuit main protection. The invention can accurately and selectively disconnect the fault busbar, control the short-circuit fault influence area in the minimum range and reduce the use of the direct current breaker.
Description
Technical Field
The invention relates to the field of ship electric propulsion, in particular to a device and a method for realizing direct-current networking of a ship electric propulsion system.
Background
Compared with the traditional alternating current networking technology of ships, the direct current networking technology of the ships has the technical advantages that the parallel operation is not needed, the voltage frequency and/or the phase position are matched before the system runs, and the rotating speed of the diesel generator can be adjusted according to the actual load, so that the fuel oil rate of the diesel engine is improved, the diesel generator set is always kept at the most economical rotating speed, the working efficiency of the system is improved, and meanwhile, the size and the weight of the whole ship electric propulsion system can be reduced. Therefore, many ship automation enterprises consider the dc networking technology as a development direction in the field of future ship electric propulsion systems. However, the current ship direct-current networking technology also has a series of restriction factors limiting the development thereof, including how a relay protection strategy in the direct-current networking technology breaks a fault line or equipment in a minimum range when a fault occurs, so as to ensure the selectivity of protection, and reduce the usage amount of a direct-current circuit breaker as much as possible to reduce the cost and improve the market competitiveness, which are problems to be solved by ship direct-current networking.
Disclosure of Invention
The invention needs to provide a device which can not only accurately judge the short circuit occurrence position of the ship electric propulsion system and quickly disconnect and protect the protection device in the region by using a differential protection signal, but also play a role in isolating a fault line from other normally working circuits in the ship electric propulsion system direct-current networking device so as to control the fault influence in a minimum range, and simultaneously can provide a device for realizing the ship electric propulsion system direct-current networking with the effect of reducing the usage amount of a direct-current circuit breaker, thereby effectively controlling the manufacturing cost of the ship direct-current networking scheme and improving the competitiveness of the ship electric propulsion system.
In order to solve the above technical problem, the present invention provides a device for implementing dc networking of a ship electric propulsion system, including a plurality of dc busbars, a busbar switch connecting the dc busbars, and a power generation path and a load path connected to each dc busbar, wherein the device further includes a busbar short circuit protection circuit, wherein the protection circuit includes: the first protection module is arranged at an alternating current section in each power generation path and used for being disconnected after a protection signal is obtained; the current acquisition module is arranged at the access points of the direct-current busbar, the power generation passage, the load passage and the bus coupler switch respectively and is used for acquiring the current at each access point; and the monitoring control module is used for calculating the differential monitoring current of each section of direct-current busbar according to the current at each access point, determining the position of a short-circuit fault busbar in the current device by using a preset differential signal threshold value, generating corresponding protection signals, and sending the protection signals to the first protection module connected with the fault busbar and the busbar switch so as to isolate the fault busbar from a power generation passage of the device and other busbars.
Preferably, the protection circuit further includes: the second protection module is arranged at the direct current section in each load path and is used for acquiring the input current of the current load path, disconnecting the current load path when the input current reaches or is higher than a preset load protection current threshold value and isolating the current load path from the direct current bus section connected with the current load path so as to protect the current load path; or the second protection module is configured to obtain an input current for a current load path, determine, based on the input current, heat accumulated by the current load path, disconnect the current load path from a dc bus segment connected to the current load path when the heat reaches or is higher than a preset load protection heat threshold, and protect the current load path.
Preferably, the monitoring control module is configured to receive the magnitude and direction of the current of each access point, and perform vector superposition processing on the current of the access point related to the same dc bus bar to obtain the differential monitoring current for each dc bus bar, where the access point related to the current dc bus bar includes: the system comprises an output end of each power generation path connected to the current direct current bus bar section, an input end of each load path connected to the current direct current bus bar section, and an access point of the bus coupler switch connected to the current direct current bus bar section.
Preferably, the differential signal threshold is greater than 100A.
Preferably, the first protection module adopts an alternating current circuit breaker, the second protection module adopts a fuse, and the bus tie switch adopts a direct current circuit breaker.
Preferably, the fusing time of the second protection module is longer than the action time of the bus tie switch and the alternating-current segment protection equipment of the current load path.
Preferably, when the load device in the load path is a daily electrical device, the apparatus further includes a secondary bus, where the secondary bus is located between the output terminal of the transformer in the load path and the input terminal of the daily electrical device, and further, the busbar short-circuit protection circuit further includes: the secondary protection module is arranged at the input end of a connection point of a current load path and the secondary bus and used for being disconnected after the protection signal aiming at the load path is obtained; the monitoring control module is connected with the secondary protection module and is further used for sending the protection signal to the secondary protection module in the load path connected with the fault busbar after the protection signal aiming at the short-circuit fault busbar is generated so as to isolate the fault busbar from the secondary busbar.
In another aspect, a method for implementing direct current networking of a ship electric propulsion system is provided, where the method implements functions of locating and protecting a faulty busbar section in the direct current networking by using the apparatus as described above, and the method includes the following steps: the current collection module collects currents at each access point, wherein the current collection module is arranged at the access points of the direct-current busbar, the power generation path, the load path and the bus coupler switch respectively; the monitoring control module calculates differential monitoring current of each section of direct current busbar according to the current at each access point, determines the position of a short-circuit fault busbar in the current direct current networking by using a preset differential signal threshold value, generates a corresponding protection signal and sends the protection signal to a first protection module connected with the fault busbar and the busbar switch; and the first protection module is disconnected after acquiring the protection signal so as to isolate the fault busbar from a power generation passage of the device and other busbars, wherein the first protection module is arranged at an alternating current section in each power generation passage.
Preferably, the method further comprises: the second protection module acquires input current aiming at a current load path, and is disconnected when the input current reaches or is higher than a preset load protection current threshold value, so that the current load path is isolated from a direct-current bus bar section connected with the current load path to protect the current load path; or the second protection module obtains an input current for a current load path, determines heat accumulated by the current load path based on the input current, and disconnects the current load path from a direct-current bus bar section connected with the current load path when the heat reaches or is higher than a preset load protection heat threshold value so as to protect the current load path, wherein the second protection module is arranged in the direct-current section of each load path.
Preferably, the monitoring control module receives the magnitude and direction of the current of each access point, and performs vector superposition processing on the current of the access point related to the same dc bus bar to obtain the differential monitoring current for each dc bus bar, where the access point related to the current dc bus bar includes: the system comprises an output end of each power generation passage connected with the current direct-current busbar section, an input end of each load passage connected with the current direct-current busbar section, and an access point of the bus-coupled switch connected with the current direct-current busbar section.
Compared with the prior art, one or more embodiments in the above scheme can have the following advantages or beneficial effects:
the invention applies the differential protection principle to the direct current network as the main protection of the direct current bus short circuit, and then uses the alternating current circuit breaker at the front end of the rectifier as the instantaneous protection in the main protection of the direct current bus short circuit, so that the whole ship direct current network only uses the direct current circuit breaker at the bus-coupled switch and is switched off when the corresponding bus is short-circuited. In addition, a direct current fuse at the front end of the inverter is used as short-time delay protection in direct current busbar short circuit main protection, and is used as short-circuit backup protection and overload protection of a load path. Therefore, when a short-circuit fault occurs in the ship direct-current busbar, the fault line can be accurately and selectively disconnected, the short-circuit fault influence area is controlled in a minimum range, and meanwhile, when the short-circuit fault occurs in a line except the direct-current busbar or other segmented busbars, the protection electric appliance in the normal busbar line does not generate misoperation. In addition, the invention reduces the use of the direct current breaker and ensures that when the section of busbar has short-circuit fault, the lines corresponding to other normal busbars of the device can be quickly and selectively protected.
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
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a first example of an overall structural schematic diagram of an apparatus for implementing direct-current networking of a marine electric propulsion system according to an embodiment of the present application.
Fig. 2 is a specific structural schematic diagram of an apparatus for implementing direct-current networking of a marine electric propulsion system according to an embodiment of the present application.
Fig. 3 is a second example of the overall structural schematic diagram of the apparatus for implementing dc networking of the marine electric propulsion system according to the embodiment of the present application.
Fig. 4 is a schematic diagram of a differential monitoring current signal of a current dc bus segment of the apparatus for implementing dc networking of a marine electric propulsion system when no short-circuit fault occurs according to the embodiment of the present application.
Fig. 5 is a schematic diagram of a differential monitoring current signal of a current dc bus segment of the apparatus for implementing dc networking of a marine electric propulsion system according to the embodiment of the present application when a short-circuit fault occurs.
Fig. 6 is a step diagram of a method for implementing dc networking of a marine electric propulsion system according to an embodiment of the present application.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.
Compared with the traditional alternating current networking technology of ships, the direct current networking technology of the ships has the technical advantages that the parallel operation is not needed, the voltage frequency and/or the phase position are matched before the system runs, and the rotating speed of the diesel generator can be adjusted according to the actual load, so that the fuel oil rate of the diesel engine is improved, the diesel generator set is always kept at the most economical rotating speed, the working efficiency of the system is improved, and meanwhile, the size and the weight of the whole ship electric propulsion system can be reduced. Therefore, many ship automation enterprises consider the dc networking technology as a development direction in the field of future ship electric propulsion systems. However, the current ship direct-current networking technology also has a series of restriction factors limiting the development thereof, including how a relay protection strategy in the direct-current networking technology breaks a fault line or equipment in a minimum range when a fault occurs, so as to ensure the selectivity of protection, and reduce the usage amount of a direct-current circuit breaker as much as possible to reduce the cost and improve the market competitiveness, which are problems to be solved by ship direct-current networking.
In order to overcome the defects in the prior art, the embodiment provides a device and a method for realizing direct-current networking of a ship electric propulsion system. The device and the method form a protected area by an area corresponding to each section of direct-current busbar, an alternating-current circuit breaker is arranged at the front end of a rectifier in each path of power generation passage, a differential monitoring current signal of each protected area is monitored in real time by using a differential protection principle, when a certain area (a certain section of direct-current busbar) is judged to be in fault, a differential protection signal is immediately generated and sent to devices such as the alternating-current circuit breaker and a direct-current busbar switch in the area, the direct-current busbar of the corresponding protected area is driven to be isolated from the power generation passage and other busbars in a system, and a main protection strategy for the direct-current busbar short-circuit fault is formed. Furthermore, a fuse is arranged at the front end of the inverter in each load path, fusing protection control is actively carried out by detecting an input current signal of the load path, short delay protection in a direct-current busbar short circuit main protection strategy is formed, meanwhile, backup delay protection can be provided for short circuit protection of the direct-current busbar load side under the condition that short circuit protection action is not timely carried out on the alternating-current side of the load path, and corresponding overload protection is provided when the running load of the load side is overlarge.
Referring to fig. 2, a conventional dc networking device for a ship power system includes: the direct current bus-bar combination power supply system comprises a plurality of direct current bus- bars 5 and 6, a direct current bus-bar switch 7 for connecting the direct current bus-bars in series, a plurality of power generation paths 201 for providing direct current power connected to each direct current bus-bar and a plurality of load paths 202 for obtaining direct current power energy from the direct current bus-bar. Wherein, each power generation path comprises a generator (for example, a diesel generator) 1 and a rectifier 3 which are connected in sequence. Each load path 202 includes at least one first type load path and/or at least one second type load path. The first-type load path includes an inverter 9 and a motor load 10 (load device) connected in this order; the second type load path includes an inverter 9, a transformer 11, and other load devices (e.g., household electrical appliances) 12 connected in this order. Further, the direct-current networking device of the ship power system in the embodiment of the invention is divided into a plurality of protected areas, and the protected areas are a current-section direct-current busbar, a multi-path power generation path 201 connected with the current-section direct-current busbar and a multi-path load path 202. The connection point of the power generation path 201 and the dc busbars 5 and 6 is the power input point of the dc busbar, and the connection point of the load path 202 and the dc busbars 5 and 6 is the power output point of the dc busbar.
Example one
Fig. 1 is a first example of an overall structural schematic diagram of an apparatus for implementing direct-current networking of a marine electric propulsion system according to an embodiment of the present application. Fig. 2 is a specific structural schematic diagram of an apparatus for implementing direct-current networking of a marine electric propulsion system according to an embodiment of the present application. As shown in fig. 1 and 2, the device of the present invention includes the same structural components as those of the conventional dc networking device for the ship power system: a plurality of sections of direct current buses 5, 6; a (direct current) bus-bar switch 7 for connecting each section of direct current bus bar; a power generation path 201 connected to each section of direct current bus (direct current bus in each protected area); and a load path 202 connected to each dc bus (dc bus in each protected area). Each power generation path 201 comprises a generator 1 and a rectifier 3 which are connected in sequence, and the output end of the rectifier 3 is connected to the power input point of the direct-current busbar. The load path 202 comprises two types, the first type of load path comprises an inverter 9 and a motor 10 which are connected in sequence, and the input end of the inverter 9 is connected to a power output point of a direct current bus; the second type of load path comprises an inverter 9, a transformer 11 and other daily loads (daily electrical equipment) 12 which are connected in sequence, wherein the input end of the inverter 9 is connected to a power output point of a direct current bus. Because the invention provides a direct-current networking device of a ship electric propulsion system with busbar short circuit monitoring and protecting functions, the device in the embodiment of the invention also comprises the following components: busbar short-circuit protection circuit.
Wherein, female short-circuit protection circuit that arranges includes: at least one first protection module 2, at least one current collection module 4 and a monitoring control module 13. Specifically, the first protection module 2 is disposed on an ac line portion in each power generation path, and is configured to be disconnected after receiving a protection signal, so that an input end and an output end of the first protection module are in a disconnected state. In one embodiment, one first protection module 2 is disposed in each power generation path 201, and is specifically disposed between the output end of the generator 1 and the input end of the rectifier 3 in the power generation path 201.
The current collection module 4 is disposed at the access points of the dc bus bar, the power generation path 201, the load path 202, and the (dc) bus tie switch 7, and is configured to collect the current at each access point. In one embodiment, each access point connected to the same dc bus bar is provided with one current collection module 4, where the access points connected to the same dc bus bar include: at least one power input point connected to the power generation path 201, at least one power output point connected to the load path 202, and a busbar connection point connected to the dc busbar switch 7 at the busbar connection point.
The monitoring control module 13 is connected with each current collection module 4, the bus coupler switch 7 and each first protection module 2. The module 13 is configured to calculate a differential monitoring current of each segment of the dc bus according to the received current at each access point, determine whether a short-circuit fault bus exists in the current device by using a preset differential signal threshold, if so, determine a position of the short-circuit fault bus and generate a corresponding protection signal (for the fault bus), and further send the current protection signal to a control end of the bus tie switch 7 connected to the fault bus and a control end of the first protection module 2 in the power generation path 201 connected to the fault bus, so as to isolate the fault bus from the power generation path of the device and other bus portions.
Referring to fig. 2, a short-circuit state monitoring and protecting process for the segment of dc bus corresponding to each protected area is described in detail. In particular, the current collection module 4 within each protected area is used to collect the magnitude and direction of the current at the corresponding access point. In the embodiment of the present invention, the current collection module 4 in the embodiment of the present invention employs a direct current sensor, and the direct current sensor is configured to detect the amplitude and direction of a direct current at a corresponding access point by using the monitoring control module 13, and superimpose the amplitude and direction to form a differential monitoring current signal for the direct current bus bar. Furthermore, each collected direct current signal is positive when the current flows to the busbar in the current direction, and the current flows out of the busbar in the current direction and is negative.
Then, the monitoring control module 13 is configured to receive the magnitude and direction of the current of all the access points in each protected area, and perform vector superposition processing on the current of the access point related to the same dc bus bar to obtain a differential monitoring current corresponding to each dc bus bar segment. Wherein the associated access points within each protected area comprise: the output end of each power generation path 201 (i.e. at least one power input point connected to the power generation path 201) connected to the current dc bus bar segment, the input end of each load path 202 (i.e. at least one power output point connected to the load path 202) connected to the current dc bus bar segment, and the buscouple switch connection point of the buscouple switch 7 connected to the current dc bus bar segment.
Then, the monitoring control module 13 is configured to compare the differential monitoring current for each dc bus with a preset differential signal threshold, determine whether a differential monitoring current corresponding to a protected area reaches or exceeds the differential signal threshold, and if so, determine that the section of the dc bus in the protected area corresponding to the differential monitoring current reaching or exceeding the differential signal threshold is a short-circuit fault bus section, which indicates that a fault phenomenon of a two-pole short circuit or a two-pole ground short circuit occurs in the section of the fault bus, thereby determining a position of the short-circuit fault bus. If not, the fault phenomenon that two poles of the direct current bus bar sections are short-circuited or two poles of the direct current bus bar sections are short-circuited in real time is avoided, and real-time comparison is needed to be carried out continuously. It should be noted that, in order to ensure the accuracy of fault detection, the differential signal threshold should not be set too low, mainly because the dc bus may have interference due to influence factors such as distributed capacitance effect or leakage current in the practical application process, but the current amplitude of these interference factors is only milliampere, and the short-circuit current often has tens of thousands of amperes, so the differential signal threshold may be set to be greater than 100A.
Finally, after the position of the short-circuit fault busbar is determined, the monitoring control module 13 is configured to immediately generate a protection signal for the fault busbar, and send the current protection signal to the control end of the dc busbar switch 7 connected to the fault busbar and the control end of the first protection module 2 in each of the power generation paths 201 connected to the fault busbar, so as to drive the corresponding dc busbar switch 7 and the first protection module 2 to be in a disconnected state, so that the current section of the fault busbar is isolated from other sections of the dc busbars, and the current section of the fault busbar is isolated from a line or an electrical device (e.g., a generator) on the input side connected to the current section of the fault busbar. Further, in the embodiment of the present invention, the first protection module 2 employs an ac circuit breaker, and the (dc) bus-bar switch 7 employs a dc circuit breaker. Therefore, the invention uses the direct current circuit breakers as few as possible and utilizes the differential protection principle to realize the short-circuit protection control process aiming at the direct current bus.
In addition, in the embodiment of the present invention, the busbar short-circuit protection circuit further includes at least one second protection module 8. Specifically, the second protection module 8 is disposed in the dc line portion of each load path 202, and is connected to each current collection module 4 located at the load path and dc bus access point (power output point). In the first embodiment, the second protection module 8 is configured to obtain an input current for a current load path, disconnect the input current when the input current reaches or is higher than a preset load protection current threshold, and isolate a line or an electrical device (e.g., a motor, a transformer, etc.) between an input end and an output end of the current load path 202 from a dc bus segment connected to the load path 202, so as to perform isolation protection on the current load path 202. In the second embodiment, the second protection module 8 is configured to obtain an input current for the current load path, determine an accumulated heat of the current load path based on the input current, open when the accumulated heat reaches or is higher than a preset load protection heat threshold, and isolate a line or an electrical device (e.g., a motor, a transformer, etc.) between an input end and an output end of the current load path 202 from a dc bus segment connected to the load path 202 to perform isolation protection on the current load path 202.
Further, in the embodiment of the present invention, the second protection module 8 employs a fuse. Specifically, a fuse is arranged at a power outlet of each section of the direct-current busbar and is used as main protection for short circuit of the section of the direct-current busbar and short delay protection and overload protection for backup of load equipment connected with the power outlet. Preferably, the fuse model needs to be selected according to the power loss in the case of overload in the load path 202, so as to be used as a short-delay protection device for short circuit of the dc bus bar. In addition, it is necessary to ensure that the fuse (the second protection module 8) is blown for a time longer than the off time of the buscouple switch 7 and/or longer than the operation time of the ac section protection device in the load path in which the fuse is currently located. The fuse blowing time may be longer than the pulse blocking operation time of the inverter 9 itself in the load path in which the fuse is currently located. The action time of the ac segment protection device in the load path may be the on-off time of the ac side ac circuit breaker of the first type of load branch circuit or the on-off time of the secondary protection module 15 of the second type of load branch circuit, which is described below.
According to the embodiment of the invention, the differential protection principle is firstly applied to the direct-current networking as the main protection of the direct-current busbar short circuit, and then the alternating-current circuit breaker at the front end of the rectifier is used as the instantaneous protection in the main protection of the direct-current busbar short circuit, so that the direct-current networking of the whole ship only uses the direct-current circuit breaker at the busbar switch and is switched off when the corresponding busbar is short-circuited. In addition, a direct current fuse at the front end of the inverter is used as short-time delay protection in direct current busbar short circuit main protection, and is used as short-circuit backup protection and overload protection of a load path.
Example two
Based on the structure of the device and the busbar short-circuit protection principle of the first embodiment, in the practical application process, each section of direct-current busbar is at least connected with one second-class load path. The load device of the second type of load path is the daily electrical device 12, so in the direct current networking device of the ship electric propulsion system, the secondary bus 14 needs to be connected to the daily electrical device.
Fig. 3 is a second example of the overall structural schematic diagram of the apparatus for implementing dc networking of the marine electric propulsion system according to the embodiment of the present application. As shown in fig. 3, when the load device in the load path 202 is the daily electrical device 12, the apparatus of the present invention further includes a secondary bus 14. Wherein, the secondary bus 14 is positioned between the output end of the transformer 9 in the current load path 202 and the input end of the daily electrical equipment 12. At this time, the input end of the connection point of the current load path 202 and the secondary bus 14 is a secondary power input point, and the connection point of the secondary bus 14 and the daily electrical equipment 12 is a secondary power output point.
Under the structure of the current device, the busbar short-circuit protection circuit further comprises a secondary protection module 15. Each load path 202 with the daily electrical equipment 12 is provided with a secondary protection module 15, which is specifically arranged at a secondary power input point corresponding to the current load path and is used for disconnecting after receiving a protection signal for the current load path, so that the input end and the output end of the secondary protection module 15 are in a disconnected state, and after the direct- current busbar 5 or 6 in the protected area where the current secondary protection module 15 is located has a short-circuit fault, power cannot flow to the secondary busbar through the non-fault section direct-current busbar and then flow to the fault section direct-current busbar. The secondary protection module 15 is an ac circuit breaker.
Further, the monitoring control module 13 is connected to the secondary protection module 15, and configured to send a protection signal to the secondary protection module 15 in the (second-class) load path 202 of the daily electrical equipment 12 connected to the faulty busbar after generating the protection signal for the short-circuit faulty busbar, so as to isolate the faulty busbar from the secondary busbar, thereby performing a short-circuit protection operation on the ac side of the load path.
In addition, in the ac line portion of the first type having the load path 202 of the electric motor 10, an ac breaker is further provided, which may be specifically provided between the inverter 9 and the electric motor 10 (not shown), and may serve as the above-mentioned current load path ac section protection device for providing corresponding open circuit protection when a short circuit occurs on the ac side of the electric motor 10. It should be noted that the ac circuit breaker herein is not related to the dc bus bar protection of the dc portion of the current load path.
EXAMPLE III
In order to facilitate understanding of the present invention, the following examples are given in more detail based on the first and second examples, but the scope of the present invention is not limited to the following specific examples. The invention provides a device with a busbar short-circuit protection function for realizing direct-current networking of a ship electric propulsion system, an electric single-wire schematic diagram of the device is shown in figure 2, and a direct-current busbar of the ship direct-current networking device is connected by two single busbars 5 and 6 through a busbar switch 7. Two single direct current buses 5 and 6 are respectively supplied with power by four 2.77MVA/690V/60Hz diesel generator sets 1 on the input side (network side), three-phase alternating current output by each generator 1 is rectified by a rectifier 3 and then is connected to the direct current buses, and an alternating current breaker 2 is arranged at the front end of each rectifier 3 for protection. Furthermore, the two single buses 5 and 6 are respectively connected with a main push motor 10 with 2.7MVA/660V/60Hz, a side push motor 10 with 1.2MVA/660V/60Hz and other load equipment 12 with 1.3MW on the load side, and each power output point on the direct-current bus bar is provided with a fuse 8 for protection. The two single buses 5 and 6 are connected with other load devices 12, and further, the direct-current buses of the two single buses 5 and 6 are correspondingly connected with the corresponding direct-current buses, and each direct-current bus is connected with the corresponding other load devices 12 through an inverter 9 and a transformer 11 in sequence. Corresponding direct current sensors 4 are arranged at the power input point and the power output point on each section of direct current bus positive electrode line and near the two sides of the bus-bar switch so as to detect the amplitude and the direction of direct current at the position.
The main protection strategy of the device with the busbar short-circuit protection function for realizing the direct-current networking of the ship electric propulsion system comprises the following contents:
(1) the ship direct-current network is composed of a bipolar suspension potential direct-current bus bar, and the bus-bar switch adopts a direct-current breaker;
(2) and the load side fuse connected with the direct current busbar is used as main protection for short circuit of the direct current busbar and short circuit backup protection and overload protection for the load side. The fuse parameters are selected according to the magnitude of the short-circuit current of the direct-current busbar and the overload condition, and the fusing time is longer than the action time of the bus-bar switch and the load path alternating-current section protection equipment. The action time of the load path alternating current section protection equipment can be the on-off time of an alternating current breaker at the front end of the motor or the rear end of the transformer, and can also be the action time of pulse sealing of the inverter;
(3) if other loads connected to the two sections of single buses pass through the inverter and the transformer, other load power supply equipment is connected to the same secondary bus together, an alternating current circuit breaker is arranged at an inlet of the secondary bus, and each alternating current circuit breaker receives a differential protection signal aiming at the section of direct current bus so as to ensure that power cannot flow to the secondary bus through the non-fault side direct current bus and then flows to the fault side direct current bus after the section of direct current bus is subjected to short circuit fault;
(4) the direct current sensor is used for detecting the amplitude and the direction of direct current at the position, and the direct current sensor is superposed to form a differential detection current signal aiming at the section of direct current busbar (bus), wherein each collected current signal is positive when the current direction flows to the busbar, and the current direction flows out of the busbar and is negative.
(5) Setting a differential signal threshold value as 100A, and when the differential detection current value aiming at the current direct current bus bar is less than 100A, judging that no short circuit phenomenon of two-pole short circuit or two-pole grounding short circuit occurs on the direct current bus bar. When the differential detection current value aiming at the current section of the direct current busbar is more than 100A, the short-circuit fault phenomenon that two poles are short-circuited or two poles are grounded on the section of the direct current busbar is judged, and a disconnection command (namely a protection signal) is sent to an alternating current circuit breaker (namely a first protection module) at the front end of a rectifier connected with the section of the direct current busbar and a direct current busbar switch, if necessary, the direct current busbar switch also comprises alternating current circuit breakers (namely second protection modules) between other loads and the section of the direct current busbar so as to quickly, accurately and selectively fully isolate the fault direct current busbar, control the fault influence range in a minimum range and ensure the operation of normal branches.
The simulation verification result in the embodiment of the invention is as follows:
fig. 4 is a schematic diagram of a differential monitoring current signal of a current dc bus segment of the apparatus for implementing dc networking of a marine electric propulsion system when no short-circuit fault occurs according to the embodiment of the present application. Fig. 4 shows a waveform diagram of a differential monitoring current signal on a current dc bus when a short-circuit fault occurs outside a dc bus (including a short circuit occurring on the input side of the bus and/or the load side of the bus), that is, when a short-circuit fault does not occur on the current dc bus. Fig. 5 is a schematic diagram of a differential monitoring current signal of a current dc bus segment of the apparatus for implementing dc networking of a marine electric propulsion system according to the embodiment of the present application when a short-circuit fault occurs. Fig. 5 shows a waveform diagram of a differential monitoring current signal on a current dc bus when a short-circuit fault occurs within a certain dc bus (including a two-pole short circuit and/or a two-pole ground short circuit), that is, when a short-circuit fault occurs on a current dc bus, the current dc bus is currently in a state of a differential monitoring current signal.
As can be seen from fig. 4 and 5, when the short-circuit fault occurs outside the range of the dc bus, the dc bus does not generate the differential monitoring current signal, i.e., does not send the open command (i.e., the protection signal) to the related circuit breaker. When a short-circuit fault occurs in the range of the current direct-current busbar, the fault direct-current busbar can generate a differential monitoring current signal of ten thousand amperes, and at the moment, the differential monitoring signal exceeds a set differential signal threshold value, and then a switching-off command (namely a protection signal) can be sent to an alternating-current circuit breaker and a busbar switch which are related to the fault direct-current busbar, so that the selectivity and the accuracy of short-circuit protection of the fault busbar are ensured. In addition, when a short-circuit fault occurs outside the range of the dc bus, the related circuit breaker needs to be controlled to be opened or closed by a protection signal aiming at the inside of other lines (such as an ac line) or equipment (such as a generator, a motor, a transformer, etc.).
Example four
Based on the devices described in the first to third embodiments, the invention further provides a method for implementing direct-current networking of a ship electric propulsion system, and the method uses the devices described in the first to third embodiments to complete the functions of positioning a fault busbar section in the direct-current networking and protecting the devices. Fig. 6 is a step diagram of a method for implementing dc networking of a marine electric propulsion system according to an embodiment of the present application. As shown in fig. 6, in step S610, the current collection module 4 collects the current at each access point. The current collection module 4 is arranged at the access point of the direct-current busbar, the power generation path, the load path and the bus coupler switch. Further, each current collection module 4 collects and measures the magnitude and direction of the current at the corresponding access point.
Step S620, the monitoring control module 13 calculates a differential monitoring current of each segment of the dc bus according to the received current at each access point, determines the position of the short-circuit fault bus in the current dc networking by using a preset differential signal threshold, generates a corresponding protection signal, and further sends the current protection signal to the first protection module 2 and the bus tie switch 7 connected to the fault bus.
Specifically, first, the monitoring control module 13 receives the magnitude and direction of the current of each access point, and performs vector superposition processing on the current of the relevant access point of the same segment of the dc bus bar to obtain a differential monitoring current for each segment of the dc bus bar, where the relevant access point of the current dc bus bar segment includes: the system comprises an output end of each power generation passage connected with the current section of direct current busbar, an input end of each load passage connected with the current section of direct current busbar and an access point of a bus-coupled switch connected with the current section of direct current busbar.
Then, the monitoring control module 13 compares the differential monitoring current for each dc bus with a preset differential signal threshold, determines whether there is a differential monitoring current corresponding to the protected area that reaches or exceeds the differential signal threshold, and if so, determines the section of the dc bus in the protected area corresponding to the differential monitoring current that reaches or exceeds the differential signal threshold as a short-circuit fault bus section, which indicates that the fault phenomenon of two-pole short circuit or two-pole ground short circuit occurs in the section of the fault bus, thereby determining the position of the short-circuit fault bus. If not, the fault phenomenon that two poles of the direct current bus bar sections are short-circuited or two poles of the direct current bus bar sections are short-circuited in real time is avoided, and real-time comparison is needed to be carried out continuously.
Finally, after the position of the short-circuit fault busbar is determined, the monitoring control module 13 immediately generates a protection signal for the fault busbar, and sends the current protection signal to the control end of the direct-current bus-bar switch 7 connected with the fault busbar and the control end of the first protection module 2 in each path of power generation path 201 connected with the fault busbar so as to drive the corresponding direct-current bus-bar switch 7 and the first protection module 2 to be in a disconnected state, so that the current section of fault busbar is isolated from other sections of direct-current busbars and power generation paths.
In step S630, the first protection module 2 is turned off after obtaining the protection signal sent from the monitoring control module 13, so as to isolate the faulty busbar from the power generation path of the device and other busbars. Wherein the first protection module 2 is arranged at the ac line part in each power generation path.
In addition, the method further includes step S640 (not shown) that the second protection module 8 obtains an input current for the current load path, and disconnects the current load path from the dc bus bar segment connected to the current load path when the input current reaches or is higher than a preset load protection current threshold, so as to protect the current load path. Or, in step S640 (not shown), the second protection module obtains an input current for the current load path, determines the amount of heat accumulated by the current load path based on the input current, disconnects the current load path when the amount of heat reaches or is higher than a preset load protection heat threshold, and isolates the current load path from the dc bus segment connected to the current load path to protect the current load path. The second protection module 8 is disposed at the dc segment of each load path, and is connected to each current collection module 4 located at the load path and the dc bus access point (power output point).
The embodiment of the invention provides a device and a method for realizing direct-current networking of a ship electric propulsion system. The method and the device are characterized in that an alternating current breaker is arranged at the front end of each rectifier, a fuse is arranged at a power outlet of each direct current busbar, a direct current sensor is arranged at a power inlet and a power outlet of a positive line of each section of direct current busbar and near a direct current bus-coupled switch, collected direct current signals are superposed to generate a differential monitoring signal, when the differential signal is greater than a set differential signal threshold value, the section of direct current busbar is determined to generate two-pole short circuit or two-pole grounding short circuit, a protection signal is generated and sent to the alternating current breaker at the front end of the rectifier connected with the section of direct current busbar and the direct current bus-coupled switch connected with the section of direct current busbar, and if necessary, the alternating current breaker at the front end of a secondary busbar is further included to successfully isolate the direct current busbar generating faults. In addition, a fuse protector is adopted at the power outlet of the direct-current busbar for protection. Therefore, short-delay main short-circuit protection of the direct-current busbar is realized through fusing of the load side, and the short-delay main short-circuit protection can be used as backup protection and overload protection of the alternating-current side short circuit of the load path.
In the ship direct-current networking power-driven system, through the protection strategy, when a ship direct-current bus bar has a short-circuit fault, a fault line can be accurately and selectively disconnected, the short-circuit fault influence area is controlled in a minimum range, and meanwhile, when the short-circuit fault occurs in a line except the direct-current bus bar or other segmented bus bars, the protection electric appliance in a normal bus bar line does not generate misoperation.
Furthermore, the invention considers the characteristics of high technical difficulty and high manufacturing cost of the current direct current breaker, reduces the use of the direct current breaker, and ensures that the lines corresponding to other normal busbars of the device can be quickly and selectively protected when the busbar of the section has short-circuit fault.
Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. The utility model provides a device for realizing boats and ships electric propulsion system direct current network deployment, includes that the multistage direct current is female arranges, connects each female generating path and the load path who allies oneself with the female switch of arranging and insert every section direct current female row of direct current, its characterized in that, the device is still including female short-circuit protection circuit of arranging, and wherein, this protection circuit possesses:
the first protection module is arranged at an alternating current section in each power generation path and used for being disconnected after a protection signal is obtained;
the current acquisition module is arranged at the access points of the direct-current busbar, the power generation passage, the load passage and the bus coupler switch respectively and is used for acquiring the current at each access point;
the monitoring control module is used for calculating differential monitoring current of each section of direct-current busbar according to the current at each access point, determining the position of a short-circuit fault busbar in the current device by using a preset differential signal threshold value, generating corresponding protection signals, and sending the protection signals to the first protection module and the busbar switch connected with the fault busbar so as to isolate the fault busbar from a power generation path of the device and other busbars;
the second protection module is arranged at the direct current section in each load path and is used for acquiring the input current of the current load path, disconnecting the current load path when the input current reaches or is higher than a preset load protection current threshold value and isolating the current load path from the direct current bus section connected with the current load path so as to protect the current load path; or
The second protection module is used for obtaining the input current aiming at the current load path, determining the heat accumulated by the current load path based on the input current, disconnecting the current load path when the heat reaches or is higher than a preset load protection heat threshold value, and isolating the current load path from the direct current busbar section connected with the current load path so as to protect the current load path.
2. The apparatus of claim 1, further,
the monitoring control module is used for receiving the magnitude and direction of the current of each access point, and performing vector superposition processing on the current of the related access points of the same section of direct-current bus bar to obtain the differential monitoring current for each section of direct-current bus bar, wherein,
the access point related to the current direct current busbar section comprises: the system comprises an output end of each power generation passage connected with the current direct-current busbar section, an input end of each load passage connected with the current direct-current busbar section, and an access point of the bus-coupled switch connected with the current direct-current busbar section.
3. The apparatus of claim 1, wherein the differential signal threshold is greater than 100A.
4. The device of claim 1, wherein the first protection module is an alternating current circuit breaker, the second protection module is a fuse, and the bus tie switch is a direct current circuit breaker.
5. The apparatus of claim 4,
and the fusing time of the second protection module is longer than the action time of the bus tie switch and the AC section protection equipment of the current load path.
6. The device according to any one of claims 1 to 5, wherein when the load device in the load path is a daily electrical device, the device further comprises a secondary bus, wherein the secondary bus is located between the output end of the transformer in the load path and the input end of the daily electrical device, and further, the busbar short-circuit protection circuit further comprises:
the secondary protection module is arranged at the input end of a connection point of a current load path and the secondary bus and used for being disconnected after the protection signal aiming at the load path is obtained;
the monitoring control module is connected with the secondary protection module and is further used for sending the protection signal to the secondary protection module in the load path connected with the fault busbar after the protection signal aiming at the short-circuit fault busbar is generated so as to isolate the fault busbar from the secondary busbar.
7. A method for realizing direct current networking of a ship electric propulsion system, which is characterized in that the method utilizes the device as claimed in any one of claims 1-6 to realize the functions of positioning and protecting a fault busbar section in the direct current networking, and the method comprises the following steps:
the current collection module collects currents at each access point, wherein the current collection module is arranged at the access points of the direct-current busbar, the power generation path, the load path and the bus coupler switch respectively;
the monitoring control module calculates differential monitoring current of each section of direct current busbar according to the current at each access point, determines the position of a short-circuit fault busbar in the current direct current networking by using a preset differential signal threshold value, generates a corresponding protection signal and sends the protection signal to a first protection module connected with the fault busbar and the busbar switch;
the first protection module is disconnected after acquiring the protection signal so as to isolate the fault busbar from a power generation path of the device and other busbars, wherein the first protection module is arranged at an alternating current section in each power generation path, and the method further comprises the following steps:
the second protection module acquires input current aiming at a current load path, and is disconnected when the input current reaches or is higher than a preset load protection current threshold value, so that the current load path is isolated from a direct-current bus bar section connected with the current load path to protect the current load path; alternatively, the first and second electrodes may be,
the second protection module obtains the input current aiming at the current load path, determines the heat accumulated by the current load path based on the input current, disconnects the current load path from the direct current bus bar section connected with the current load path when the heat reaches or is higher than a preset load protection heat threshold value, and protects the current load path,
the second protection module is arranged at a direct current section in each load path.
8. The method of claim 7, further comprising,
the monitoring control module receives the magnitude and direction of the current of each access point, and carries out vector superposition processing on the current of the relevant access points of the same section of direct-current bus bar to obtain the differential monitoring current for each section of direct-current bus bar, wherein,
the access point related to the current direct current busbar section comprises: the system comprises an output end of each power generation passage connected with the current direct-current busbar section, an input end of each load passage connected with the current direct-current busbar section, and an access point of the bus-coupled switch connected with the current direct-current busbar section.
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| WO2013121077A1 (en) * | 2012-02-15 | 2013-08-22 | Wärtsilä Finland Oy | Protection system of an electric network of a vessel |
| CN105406450A (en) * | 2015-12-03 | 2016-03-16 | 武汉华海通用电气有限公司 | Intelligent protection device for busbar short-circuit fault of marine power distribution panel |
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| CN104009452B (en) * | 2014-05-29 | 2016-10-12 | 天津大学 | A kind of protection scheme for direct-flow distribution system short trouble |
| US9745038B2 (en) * | 2014-07-11 | 2017-08-29 | General Electric Company | DC power system for marine applications |
| CN106099879B (en) * | 2016-08-09 | 2018-10-09 | 深圳供电局有限公司 | A kind of flexible direct current distribution network line differential protection system and differential protection implementation method |
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| WO2013121077A1 (en) * | 2012-02-15 | 2013-08-22 | Wärtsilä Finland Oy | Protection system of an electric network of a vessel |
| CN105406450A (en) * | 2015-12-03 | 2016-03-16 | 武汉华海通用电气有限公司 | Intelligent protection device for busbar short-circuit fault of marine power distribution panel |
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