CN112787313A - Ship direct-current power grid short-circuit protection device - Google Patents
Ship direct-current power grid short-circuit protection device Download PDFInfo
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- CN112787313A CN112787313A CN201911088716.0A CN201911088716A CN112787313A CN 112787313 A CN112787313 A CN 112787313A CN 201911088716 A CN201911088716 A CN 201911088716A CN 112787313 A CN112787313 A CN 112787313A
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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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Abstract
The utility model provides a boats and ships direct current electric wire netting short-circuit protection device, its includes the first short-circuit protection module and the second short-circuit protection module that the structure is the same and symmetry sets up, and first short-circuit protection module is including parallelly connected first electrically conductive passageway and second electrically conductive passageway, and wherein, the impedance value when first electrically conductive passageway switches on is greater than the impedance value when the second electrically conductive passageway switches on. If one side of the device is electrified and the other side of the device is electroless, the short-circuit protection module on the electrified side can skip the first conduction channel and directly transmit electric energy through the second conduction channel after receiving a closing instruction, and the short-circuit protection module on the electroless side can control the first conduction channel to transmit electric energy after receiving the closing instruction, and switches to transmit electric energy through the first conduction channel when the voltage on the right side rises to a set value, so that the impact on the whole system in the closing process due to the short-circuit fault can be avoided.
Description
Technical Field
The invention relates to the technical field of ship electric propulsion, in particular to a ship direct-current power grid short-circuit protection device.
Background
The good maneuverability of electric propulsion makes it applied in the field of ship power, and with the development of power electronic technology, the alternating current variable frequency electric propulsion device is widely applied to ships. In recent years, with the development of power electronic technology and the expansion of direct current application concepts, the electric propulsion system of the direct current power grid is beginning to be applied in the market, so as to meet the comprehensive requirements of shipowners and society on water path traffic energy conservation and environmental protection.
Compared with an alternating current power grid electric propulsion system, the direct current networking electric propulsion system has outstanding technical advantages in the aspects of distributed power supply access, energy storage release, load disturbance suppression, energy conservation, emission reduction and noise reduction, and the direct current hybrid power propulsion formed by variable-speed power generation, large-capacity energy storage and variable-frequency driving technology can effectively solve the technical problems of insufficient stability, reliability and economy of the alternating current networking electric propulsion system.
Therefore, the electric propulsion of small and medium-sized ships is developed in the aspect of direct-current networking at present based on the advantages of economical driving and space saving. Fig. 1 shows a topology diagram of an existing ac networking and dc networking electric propulsion system. The difference between the direct current networking and the alternating current networking is that a single diesel engine is directly rectified and merged into a direct current power grid, the direct current networking does not involve the problems of parallel operation of a generator and an alternating current distribution board, and meanwhile, the distribution board and a transformer at the front end are omitted in electric propulsion. The direct-current power grid has no phase requirement, so that the diesel engine set can realize variable-speed power generation according to the current load change so as to improve the efficiency of the whole electric propulsion system and improve the fuel economy of the propulsion system.
Disclosure of Invention
In order to solve the above problems, the present invention provides a ship dc power grid short-circuit protection device, which includes a first short-circuit protection module and a second short-circuit protection module that are identical in structure and symmetrically disposed, where the first short-circuit protection module includes a first conductive channel and a second conductive channel connected in parallel, and an impedance value of the first conductive channel when conducting is greater than an impedance value of the second conductive channel when conducting.
According to an embodiment of the invention, the first conductive path comprises a first controllable switch and a first protection resistor connected in series, and a circuit formed by the first controllable switch and the first protection resistor connected in series is connected between the first positive port and the second positive port of the first short-circuit protection module.
According to an embodiment of the invention, the first conductive path further includes a second controllable switch and a second protection resistor connected in series, wherein a circuit formed by the second controllable switch and the second protection resistor connected in series is connected between the first negative port and the second negative port of the first short-circuit protection module.
According to one embodiment of the invention, the second conductive path comprises:
a first direct current capacitor for connecting between a first positive electrode port and a first negative electrode port of the first short-circuit protection module;
a first port of the first switch tube forms a first positive port of the first short-circuit protection module so as to be connected with a positive electrode of a corresponding direct-current network electric pushing device, and a second port forms a second positive port of the first short-circuit protection module so as to be connected with a second positive port of the second short-circuit protection module;
a first port of the second switch tube forms a first negative port of the first short-circuit protection module for being connected with a negative electrode of a corresponding direct-current network electric pushing device, and a second port of the second switch tube forms a second negative port of the first short-circuit protection module for being connected with a second negative port of the second short-circuit protection module;
and the anode of the first diode is connected with the second port of the second switch tube, and the cathode of the first diode is connected with the second port of the first switch tube.
According to an embodiment of the invention, the first short-circuit protection module further comprises:
and one end of the first inductor is connected with the second port of the first switching tube, and the other end of the first inductor forms a second positive electrode port of the first short-circuit protection module.
According to an embodiment of the invention, the first short-circuit protection module further comprises:
and one end of the second inductor is connected with the second port of the second switching tube, and the other end of the second inductor forms a second negative electrode port of the first short-circuit protection module.
According to one embodiment of the invention, the inductance values of the first and second inductors are in the microhenry range.
According to an embodiment of the invention, the first short-circuit protection module further comprises:
a chopper circuit connected between the first positive port and the first negative port of the first short-circuit protection module.
According to an embodiment of the present invention, the chopper circuit includes:
a third switching tube, a first port of which is connected with the first positive electrode port of the first short-circuit protection module;
and one end of the chopper resistor is connected with the second port of the third switching tube, and the other end of the chopper resistor is connected with the first negative electrode port of the first short-circuit protection module.
According to an embodiment of the present invention, the chopper circuit further includes:
and a first port of the fourth switching tube is connected with a second port of the third switching tube, and a second port of the fourth switching tube is connected with a first negative port of the first short-circuit protection module.
According to an embodiment of the present invention, the chopper circuit further includes:
and the anode of the clamping diode is connected with the first cathode port of the first short-circuit protection module, and the cathode of the clamping diode is connected with the second port of the third switching tube.
According to one embodiment of the invention, the first direct current capacitor is integrated in the chopper circuit.
According to one embodiment of the present invention, each switching tube includes a switching section and a freewheeling diode connected in anti-parallel with the switching section.
The ship direct-current power grid short-circuit protection device provided by the invention has the redundant turn-off protection capability, and simultaneously has the functions of energy allocation, voltage control, current/power limitation and the like among direct-current buses, and can realize active control of a direct-current power grid.
The short-circuit protection device adopts a back-to-back DC/DC optimized structure, so that a sectional topology can be formed, each side of the sectional topology is formed into a cabinet, the cabinet bodies are completely in mirror symmetry, and the two parts are connected together to form a group of short-circuit protection devices. The structure can evenly distribute each group of short-circuit protection devices at two ends of the converter cabinet which needs to be electrically connected, thereby ensuring the symmetry of the cabinet bodies at two sides after the short-circuit protection devices are arranged in the cabinet bodies. Meanwhile, after half protection devices (namely, one short-circuit protection module) are arranged at two ends of each converter cabinet, a plurality of groups of converter cabinets can conveniently form a main stream bus or a direct current ring network, and therefore engineering application adaptability of the device is greatly improved.
And each short-circuit protection switch can be independently controlled, so that chopping and single-side protection module actions in the half cabinet can be independently controlled, real-time cooperativity of turn-off and chopping is ensured, and high-precision time sequence control ensures the reliability of transient overvoltage suppression of turn-off of the solid-state switch.
Meanwhile, the short-circuit protection device adopts a positive and negative electrode redundancy shutoff topological structure, so that the whole device can still normally pass current and can be normally shut off when a certain switching tube fails, and the reliability of the whole device is improved.
In addition, the short-circuit protection device adopts the symmetrical follow current mode of the switching tube to raise the voltage between the switching bridges at the moment of switching off the solid-state circuit breaker, and the voltage is removed from the two sides of the solid-state switch at the moment of switching off the solid-state switch instead of a bypass RLC circuit and an MOV circuit, so that the RLC circuit and the MOV circuit are omitted, the number of devices is reduced, and the cost of the whole device is reduced, and the size of the whole device is reduced.
If one side of the device is electrified and the other side of the device is electroless, the short-circuit protection module on the electrified side can skip the first conduction channel and directly transmit electric energy through the second conduction channel after receiving a closing instruction, and the short-circuit protection module on the electroless side can control the first conduction channel to transmit electric energy after receiving the closing instruction, and switches to transmit electric energy through the first conduction channel when the voltage on the right side rises to a set value, so that the impact on the whole system in the closing process due to the short-circuit fault can be avoided.
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 following briefly introduces the drawings required in the description of the embodiments or the prior art:
FIG. 1 is a schematic topology of an existing AC and DC networked electric propulsion system;
fig. 2 is a schematic structural view of a conventional hybrid circuit breaker;
FIG. 3 is a schematic diagram of a prior art solid state crowbar;
fig. 4 is a schematic structural diagram of a short-circuit protection device for a direct-current power grid of a ship according to an embodiment of the invention;
fig. 5 is a schematic structural diagram of a short-circuit protection device for a direct-current power grid of a ship according to an embodiment of the invention;
fig. 6 is a schematic structural diagram of a short-circuit protection device for a direct-current power grid of a ship according to another embodiment of the invention;
fig. 7 is a schematic structural diagram of a pure solid-state short-circuit protection device for a ship direct-current power grid according to another embodiment of the invention;
fig. 8 is a schematic structural diagram of a pure solid-state short-circuit protection device for a ship direct-current power grid according to still another embodiment of the invention.
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.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details or with other methods described herein.
The ship electric propulsion system adopting the direct-current networking mode reduces large-scale equipment such as an alternating-current distribution board, a transformer and the like, saves a large amount of space and lightens the weight of the whole system. However, since the grid is changed from an ac bus to a dc bus, this also raises technical problems in terms of grid protection.
The traditional alternating current power grid bus-bar switch is provided with a mature circuit breaker as short-circuit breaking protection, and the alternating current circuit breaker realizes breaking of power grid faults by using the alternating current zero crossing point characteristic. The direct-current power grid has no alternating-current characteristics, and the current rises rapidly at the moment of short circuit, so that the breaking of the direct-current power grid during fault has extremely high technical difficulty.
With the rise of the terrestrial direct current power grid in recent years, direct current circuit breakers emerge to be researched and applied with hot tide. The main characteristics of the land DC power grid protection device (DC breaker) are the form of a hybrid breaker, no space limitation, single-stage turn-off, high-voltage low-current turn-off within a few milliseconds.
At present, ship direct current power grid circuit breakers at home and abroad mainly have two types. One type is realized by a converter (DC/DC), and is characterized by realizing active allocation of power grid energy and microsecond-level turn-off, but the power loss is large and the cost is high.
Another class is circuit breakers derived from terrestrial dc network circuit breakers (including hybrid circuit breakers and solid state circuit breakers without mechanical parts, as shown in fig. 2 and 3). The hybrid circuit breaker has the advantages of low normal working loss and the disadvantages of large volume, switching-off time of only millisecond level, complex switching-off control and high cost. The solid-state circuit breaker has advantages in the aspects of size, cost and the like, and is suitable for application conditions of ships with low full-power continuous through-current probability. Because the load and the power supply on the ship direct-current power grid are uniformly distributed on the bus, the pure solid-state circuit breaker does not cause a large amount of energy loss under the normal working condition of the ship, and the pure solid-state circuit breaker (comprising a DC/DC converter type and a common solid-state type) is suitable for the ship direct-current power grid.
The two types of direct current power grid protection devices are used for ships, and have the following main problems: the current transformer (DC/DC) type protection device has no redundant function, large power loss, relatively large occupied volume of the reactor and high cost; the solid-state circuit breaker transient turn-off can excite high voltage pulse at two ends of the circuit breaker, so that the circuit breaker must be provided with energy absorption circuits such as RLC, MOV and the like which respond to ensure that the solid-state switch is not damaged at the turn-off moment, and the overvoltage at the turn-off moment is required to be restrained, so that the solid-state circuit breaker has no advantages in volume, cost and circuit complexity, and does not have the energy allocation, current limiting/power functions of a current transformer (DC/DC) type protection device.
At present, domestic and foreign civil direct current ship electric propulsion systems basically adopt solid-state protection devices. Because the transient switching-off of the solid-state circuit breaker can excite high-voltage pulses at two ends of the circuit breaker when a direct-current power grid fails, the circuit breaker must be provided with a responsive energy absorption circuit to ensure that the solid-state switch is not damaged at the moment of switching-off, and for the reasons, the common solid-state circuit breaker commonly used in the field of ships also has the problems of large volume and relatively complex circuit structure.
Aiming at the problems in the prior art, the invention provides a novel ship direct-current power grid short-circuit protection device. Fig. 4 shows a schematic structural diagram of the ship dc grid short-circuit protection device in this embodiment.
In consideration of the requirement on the layout of the electric propulsion system in practical application of the ship, the direct-current networking electric propulsion device may be connected by two or more bus bars through a bus-bar switch, and meanwhile, the cabinet body may be placed in a centralized or distributed manner according to the condition of the ship cabin. In order to ensure the symmetry of each section of cabinet body, satisfy different layout mode requirements, and can adapt to the bus arrangement requirement of single line and annular direct current network, the ship direct current power grid short-circuit protection device that this embodiment provided has adopted back-to-back structure.
Specifically, as shown in fig. 4, the short-circuit protection device for a ship dc power grid provided in this embodiment preferably includes at least two short-circuit protection modules (e.g., a first short-circuit protection module 401 and a second short-circuit protection module 402) that have the same structure and are symmetrically disposed, and the short-circuit protection modules are connected through a dc bus and are respectively connected to corresponding dc networking power pushing devices.
In this embodiment, the dc short-circuit protection device is designed as two symmetrically distributed electrical cabinets, and the two cabinets are respectively arranged at two ends of a bus of the two dc networking electric pushing devices. Two short-circuit protection module cabinet bodies between the direct current network deployment electric pushing device form a set of direct current short-circuit protection device (bus connection switch) through female arranging or cable junction, and the bus connection switch is all arranged at the both ends of every cabinet body, just so can make the cabinet body not only guarantee the symmetry but also be convenient for constitute direct current looped netowrk.
However, if the dc protection devices are arranged in a centralized manner (i.e. one device is arranged in one cabinet), the arrangement of the short-circuit protection devices on one side of the cabinet may cause a great difference between the busbars/connecting wires (stray inductances) on two ends of the short-circuit protection devices, which is inconvenient for the symmetric distribution of the dc propulsion system devices and affects the protection control.
Fig. 5 shows a specific structural schematic diagram of the short-circuit protection device for the ship dc power grid in the embodiment. Since the short-circuit protection modules have the same structure, for convenience of description, only one of the short-circuit protection modules is taken as an example for emphasis.
As shown in fig. 5, in this embodiment, the first short-circuit protection module 401 includes: a first conductive path 401a and a second conductive path 401 b. The first conductive channel 401a is connected in parallel with the second conductive channel 401b, and the impedance value of the first conductive channel 401a when conducting is larger than the impedance value of the second conductive channel 401b when conducting.
Specifically, as shown in fig. 5, in the present embodiment, the second conductive path 401b preferably includes: a first switch tube 501, a first diode 502, a second switch tube 503, a first inductor 504 and a second inductor 505. A first port of the first switch tube 501 forms a first positive port of the first short-circuit protection module for connecting with a positive electrode of a corresponding dc networking power push device, and a second port of the first switch tube is connected with a first port of the first inductor 504. The second port of the first inductor 504 then forms a second positive port of the first short-circuit protection module for connection with a corresponding port (e.g. a second positive port) of another short-circuit protection module (e.g. a second short-circuit protection module) via a dc bus.
Similarly, a first port of the second switch tube 503 forms a first negative port of the first short-circuit protection module for connecting with a negative electrode of the corresponding dc networking power pusher, and a second port thereof is connected with a first port of the second inductor 505. The second port of the second inductor 505 then forms a second negative port of the first short-circuit protection module for connection with a corresponding port (e.g. a second negative port) of another short-circuit protection module (e.g. a second short-circuit protection module) via the dc bus.
The anode of the first diode 502 is connected to the second port of the second switch tube 503, and the cathode thereof is connected to the second port of the first switch tube 501.
Specifically, the switching tube employed in the present embodiment preferably includes a switching section and a freewheeling diode connected in anti-parallel with the switching section. For example, when the switch tube is implemented by an IGBT module, the first port of the first switch tube 501 may be a collector of the IGBT module, and the second port may be an emitter of the IGBT module.
Of course, in other embodiments of the present invention, the switch tube may be implemented by other reasonable devices (e.g., IGCT), and the present invention is not limited thereto.
For the existing ship direct-current power grid short-circuit protection device, when a certain switching device on a DC + bus is damaged, the device cannot realize fault disconnection operation. To solve this problem, in this embodiment, the first short-circuit protection module includes the second switch tube 503. The second switch tube 503 can preferably be turned off or turned on simultaneously with the first switch tube 501, so that a protection mode with high redundancy, in which positive and negative buses of the ship power grid are turned off simultaneously, can be realized. Meanwhile, when one of the switch tubes corresponding to the positive and negative buses is closed, the loop can be cut off, so that external power supply is stopped.
Therefore, the ship direct-current power grid protection method is combined with the characteristics of the ship direct-current power grid, and researches show that the ship direct-current power grid is suitable for a protection mode with high redundancy, namely, the positive bus and the negative bus are turned off simultaneously. Therefore, the ship direct-current power grid short-circuit protection device provided by the embodiment introduces the second switching tube arranged at the negative electrode of the direct-current bus, and the redundancy of fault turn-off can be enhanced under the condition that energy allocation and current limiting/power control are not influenced.
It should be noted that in other embodiments of the present invention, when the second switch 503 is not configured, the anode of the first diode also forms the second cathode port of the short-circuit protection module, and the second inductor 505 forms the first cathode port of the first short-circuit protection module without the end connected to the first diode.
Meanwhile, considering the energy scheduling and bidirectional voltage regulating functions of removing the DC/DC, the short-circuit protection device provided by the embodiment only keeps the transient turn-off and normal through-current functions. The change that brings like this is that, reactor, the condenser in the topology can be saved to first short-circuit protection module in this embodiment, just also practiced thrift a large amount of spaces through saving the reactor, and can reduce the duration that flows through diode current on the positive negative busbar after the switch is closed through saving the condenser.
In this embodiment, since the boost function is not required to be considered after the DC/DC function is removed, the first short-circuit protection module in this embodiment may also omit the switching device between the positive and negative buses. Considering that the left side and the right side of a short-circuit protection device (in detail, a group of switching tubes playing a turn-off role) are connected by a longer busbar/cable, and the stray inductance of the short-circuit protection device can cause overvoltage exceeding at two sides of the switching tubes at the moment of fault turn-off, a diode is further arranged between a first switching tube and a second switching tube of a first short-circuit protection module to enable the switching tubes to continue current at the turn-off moment, so that the voltage value at the turn-off rear end is improved, the voltage difference between the switching tubes is reduced, and the switching devices are prevented from being damaged.
It should be noted that, in this embodiment, the first inductor 504 and the second inductor 505 may also represent stray inductors connected to the bus bar or the conducting wire, and the inductance value thereof is usually micro henry.
In this embodiment, the first conductive path 401a preferably includes a first controllable switch 510 and a first protection resistor 511 connected in series. The circuit formed by the first controllable switch 510 and the first protection resistor 511 connected in series is connected between the first positive terminal and the second positive terminal of the first short-circuit protection module 401.
In addition, in this embodiment, preferably, the first conductive path 401a further includes a second controllable switch 512 and a second protection resistor 513 according to actual requirements. A circuit formed by connecting the second controllable switch 512 and the second protection resistor 513 in series is connected between the first negative terminal and the second negative terminal of the first short-circuit protection module 401.
In this embodiment, when the voltage of the first end of the first short-circuit protection module 401 (i.e., the dc voltage on the left side in fig. 4) is not equal to the voltage of the first end of the second short-circuit protection module (i.e., the dc voltage on the right side in fig. 4), a voltage difference is formed between the first short-circuit protection module and the second short-circuit protection module. At this moment, the ship direct-current power grid short-circuit protection device firstly utilizes the first conductive channel in the first short-circuit protection module and the second short-circuit protection module to transmit electric energy. Because the impedance value when the first conducting channel is conducted is larger than the impedance value when the second conducting channel is conducted, the current abrupt change in the conducting channels is reduced.
Meanwhile, in this embodiment, the first short-circuit protection module and the second short-circuit protection module are respectively connected to different dc networking electric pushing devices, when the dc networking electric pushing device on one side is in an electric state and the dc networking electric pushing device on the other side is in an electric-free state, the short-circuit module corresponding to the dc networking electric pushing device in the electric state preferably uses the second conductive channel thereof for electric energy transmission, and the short-circuit module corresponding to the dc networking electric pushing device in the electric-free state preferably uses the first conductive channel thereof for electric energy transmission, and after the dc networking electric pushing device in the electric-free state is powered on, the short-circuit protection module is converted into the second conductive channel thereof for electric energy transmission.
It should be noted that, in other embodiments of the present invention, the first conductive path and/or the second conductive path may also be implemented in other reasonable circuit forms, and the present invention is not limited thereto.
Considering that the protection device has a longer dc bus bar at both ends, the stray inductance thereof can cause instantaneous induction high voltage to be generated at the outer side (C pole) of the switching tube at the moment of switching off under the fault condition. Therefore, in this embodiment, the first short-circuit protection module preferably further includes a chopper circuit 401c in order to reduce the instantaneous voltage outside the switch at the moment of turning off. The chopper circuit 401c is connected between the first positive terminal and the first negative terminal of the first short-circuit protection module.
Specifically, in the present embodiment, the chopper circuit 401c preferably includes: a third switch tube 506, a chopper resistor 507 and a fourth switch tube 508. A first port of the third switching tube 506 is connected to a first positive port of the first short-circuit protection module, a second port of the third switching tube is connected to a first port of the fourth switching tube 508, and a second port of the fourth switching tube 508 is connected to a first negative port of the first short-circuit protection module. One end of the chopper resistor 507 is connected to the second port of the third switching tube 506, and the other end is connected to the first negative port of the first short-circuit protection module.
In this embodiment, as shown in fig. 5, the short-circuit protection module further includes a first dc capacitor 509. One end of the first dc capacitor 509 is connected to the first port of the third switching tube 506, and the other end is connected to the second port of the fourth switching tube 508. Thus, the first dc capacitor 509 is equivalently connected between the first positive terminal and the first negative terminal of the short-circuit protection module.
It should be noted that, in other embodiments of the present invention, the fourth switching tube 508 may also be replaced by a satisfactory clamping diode. At this time, the anode of the clamping diode needs to be connected with the first cathode port of the first short-circuit protection module, and the cathode needs to be connected with the second port of the fourth switching tube.
Of course, in other embodiments of the present invention, the chopper circuit 401c may not be provided with the fourth switching tube 508 according to actual needs, and the present invention is not limited to this.
Meanwhile, it should be noted that, in other embodiments of the present invention, when the short-circuit protection module does not include the chopper circuit and the disconnector, the first short-circuit protection module may still include the first dc capacitor 509, and at this time, the first dc capacitor 509 may be directly connected between the first positive terminal and the first negative terminal of the short-circuit protection module, that is, the circuit structure shown in fig. 6 is correspondingly formed.
In this embodiment, four switching tubes on the positive and negative bus bars are in a conducting state in a normal working state, and current can flow in any two directions. When the control system monitors that a short circuit occurs on one side of two ends of the short-circuit protection device, the control system can control the four switching tubes on the positive and negative buses to be switched off, and simultaneously, the chopper circuit is started to reduce the instantaneous voltage at the two ends of the short-circuit protection device. It should be noted that, in order to optimize the voltage difference between the switching tubes at the moment when the short-circuit protection device is turned off, in this embodiment, when the four valley-opening tubes on the positive and negative dc buses are controlled to be turned off, the chopper circuit is preferably configured to be in an on state, so that chopping is realized through the switching tubes on the chopper circuit, and an RL loop with a smaller resistance value is formed.
For the topology shown in fig. 5, the protective turn-off is characterized in that a pair of switching tubes at the far end side from the short-circuit area have an actual turn-off function, and two diodes on the positive and negative bus switching tubes at the near end side of the short-circuit area, diodes at the positive and negative ends, and stray inductances on two test busbars of the switching tubes at the side jointly form a transient follow current loop to raise the voltage at the turn-off rear end of the switching tube at the far end side.
In this embodiment, it is considered that different short-circuit protection modules generally have a longer dc bus bar therebetween, and stray inductance thereof may cause instantaneous induced high voltage to be generated outside the switching tube at the moment of switching off under a fault condition. Therefore, in the present embodiment, the short-circuit protection module incorporates the chopper circuit into the DC/DC type protection device with redundancy and is disposed just outside the switching tube, in order to reduce the instantaneous voltage outside the switch at the moment of turning off.
The DC/DC type short-circuit protection device with redundancy and chopping adopts a structure that chopping and circuit breakers are designed in the same cabinet, so that the original chopping function is ensured, and the chopping can be controlled to be started to reduce the overvoltage outside a switching tube through a chopping circuit (equivalent RL circuit) while the fault is disconnected.
It is noted that when the short-circuit protection arrangement is in an integrated arrangement, the different short-circuit protection modules preferably share a diode. For example, for the circuit shown in fig. 5, when the short-circuit protection device is integrally arranged, the circuit structure will be changed to the structure shown in fig. 7; this is for the circuit shown in fig. 6, and when the short-circuit protection device is integrally arranged, the circuit structure will be changed to the structure shown in fig. 8.
In this embodiment, the dc grid short-circuit protection device with redundancy and chopping adopts a mode of chopping and circuit breaker in the same cabinet, so that not only is the original chopping function ensured, but also the chopping function can be controlled to be started to reduce the overvoltage at the outer side of the switching tube through a chopping circuit (equivalent RL circuit) while the fault disconnection action is performed. Therefore, the ship direct-current power grid bus protection device provided by the embodiment can raise the voltage inside the switching tube at the turn-off moment through diode freewheeling under the condition of no traditional absorption circuit. Meanwhile, by adopting the chopping function integrated design, the ship direct-current power grid bus protection device provided by the embodiment can ensure the surge energy at the outer side of the switch tube at the moment of turning off the absorption device, so that the purpose of inhibiting the voltage lifting at the outer side of the switch tube is achieved, and the overvoltage on a switch device at the moment of turning off is ensured not to exceed the standard from the two aspects of the inner side and the outer side of the switch tube. Therefore, on the premise of ensuring the fault cutoff function of the direct-current micro-grid of the ship, the device and the cost are greatly reduced, the integration of the device is improved, and the short-circuit protection device is suitable for the direct-current micro-grid of the ship.
In this embodiment, when there is electricity on one side of boats and ships direct current electric wire netting short-circuit protection device and one side does not have electricity, can carry out the combined floodgate through two independent control's female gang switch. For example, if the left-side bus has electricity and the right-side bus has no electricity, the first short-circuit protection module on the left side can skip the first conduction channel and directly transmit the electric energy through the second conduction channel after receiving a closing instruction, and the second short-circuit protection module on the right side can control the first short-circuit protection module to transmit the electric energy through the second conduction channel after receiving the closing instruction, and switch to transmit the electric energy through the first conduction channel when the right-side voltage rises to a set value. For the second short-circuit protection module, if the voltage still cannot be raised or still is zero after the set time length is exceeded, the first short-circuit protection device reports a fault, at the moment, the conductive channel is kept in an open circuit state, and therefore electric energy cannot be transmitted, and the fact that the whole system is impacted in the switching-on process due to the fact that a short-circuit fault exists on the right side is avoided.
In this embodiment, as shown in fig. 5 again, in this embodiment, according to actual needs, the second conductive path preferably further includes a first isolation switch 514 and/or a second isolation switch 515. The first isolation switch 514 is connected in series between the first switch 501 and the first inductor 504, and the second isolation switch 505 is connected in series between the second switch 503 and the second inductor 505. In this embodiment, the isolating switch can ensure that the microgrid on one side of the ship direct-current power grid short-circuit protection device can still normally operate when the microgrid on the other side stops operating due to maintenance or failure.
As can be seen from the above description, the ship direct-current power grid short-circuit protection device provided by the present invention has the redundant turn-off protection capability, and at the same time, has the functions of energy allocation between direct-current buses, voltage control, current/power limitation, etc., and can realize active control of the direct-current power grid.
The short-circuit protection device adopts a back-to-back DC/DC optimized structure, so that a sectional topology can be formed, each side of the sectional topology is formed into a cabinet, the cabinet bodies are completely in mirror symmetry, and the two parts are connected together to form a group of short-circuit protection devices. The structure can evenly distribute each group of short-circuit protection devices at two ends of the converter cabinet which needs to be electrically connected, thereby ensuring the symmetry of the cabinet bodies at two sides after the short-circuit protection devices are arranged in the cabinet bodies. Meanwhile, after half protection devices (namely, one short-circuit protection module) are arranged at two ends of each converter cabinet, a plurality of groups of converter cabinets can conveniently form a main stream bus or a direct current ring network, and therefore engineering application adaptability of the device is greatly improved.
And each short-circuit protection switch can be independently controlled, so that chopping and single-side protection module actions in the half cabinet can be independently controlled, real-time cooperativity of turn-off and chopping is ensured, and high-precision time sequence control ensures the reliability of transient overvoltage suppression of turn-off of the solid-state switch.
Meanwhile, the short-circuit protection device adopts a positive and negative electrode redundancy shutoff topological structure, so that the whole device can still normally pass current and can be normally shut off when a certain switching tube fails, and the reliability of the whole device is improved.
In addition, the short-circuit protection device adopts the symmetrical follow current mode of the switching tube to raise the voltage between the switching bridges at the moment of switching off the solid-state circuit breaker, and the voltage is removed from the two sides of the solid-state switch at the moment of switching off the solid-state switch instead of a bypass RLC circuit and an MOV circuit, so that the RLC circuit and the MOV circuit are omitted, the number of devices is reduced, and the cost of the whole device is reduced, and the size of the whole device is reduced.
Meanwhile, a chopping circuit is introduced between the positive and negative electrode ports of the short-circuit protection device, so that the chopping circuit has the function of cooperatively inhibiting the overvoltage outside the switch bridge at the moment of switching off the solid-state switch due to fault besides the function of inhibiting the overvoltage of the direct-current bus. When the controller controls the device to break, chopping is started, and the chopping circuit can form an RL circuit to inhibit high voltage generated at the moment of turn-off, so that the two purposes of one device are realized, overvoltage at the moment of turn-off of the solid-state switch at the moment of short-circuit fault is further reduced, and the comprehensive performance of the protection device is improved.
It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures or process steps disclosed herein, but extend to equivalents thereof as would be understood by those skilled in the relevant art. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.
Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.
While the above examples are illustrative of the principles of the present invention in one or more applications, it will be apparent to those of ordinary skill in the art that various changes in form, usage and details of implementation can be made without departing from the principles and concepts of the invention. Accordingly, the invention is defined by the appended claims.
Claims (13)
1. The utility model provides a boats and ships direct current electric wire netting short-circuit protection device, its characterized in that, the device is including the first short-circuit protection module and the second short-circuit protection module that the structure is the same and symmetry sets up, first short-circuit protection module is including parallelly connected first electrically conductive passageway and the electrically conductive passageway of second, wherein, the impedance value when first electrically conductive passageway switches on is greater than the impedance value when the electrically conductive passageway of second switches on.
2. The apparatus of claim 1, the first conductive path comprising a first controllable switch and a first protection resistor in series, a circuit formed by the first controllable switch in series with the first protection resistor connected between a first positive port and a second positive port of the first short-circuit protection module.
3. The apparatus of claim 2, the first conductive path further comprising a second controllable switch and a second protection resistor connected in series, wherein a circuit formed by the second controllable switch in series with the second protection resistor is connected between the first negative port and the second negative port of the first short-circuit protection module.
4. The apparatus of any of claims 1-3, wherein the second conductive path comprises:
a first direct current capacitor for connecting between a first positive electrode port and a first negative electrode port of the first short-circuit protection module;
a first port of the first switch tube forms a first positive port of the first short-circuit protection module so as to be connected with a positive electrode of a corresponding direct-current network electric pushing device, and a second port forms a second positive port of the first short-circuit protection module so as to be connected with a second positive port of the second short-circuit protection module;
a first port of the second switch tube forms a first negative port of the first short-circuit protection module for being connected with a negative electrode of a corresponding direct-current network electric pushing device, and a second port of the second switch tube forms a second negative port of the first short-circuit protection module for being connected with a second negative port of the second short-circuit protection module;
and the anode of the first diode is connected with the second port of the second switch tube, and the cathode of the first diode is connected with the second port of the first switch tube.
5. The apparatus of claim 4, wherein the first short-circuit protection module further comprises:
and one end of the first inductor is connected with the second port of the first switching tube, and the other end of the first inductor forms a second positive electrode port of the first short-circuit protection module.
6. The apparatus of claim 5, wherein the first short-circuit protection module further comprises:
and one end of the second inductor is connected with the second port of the second switching tube, and the other end of the second inductor forms a second negative electrode port of the first short-circuit protection module.
7. The apparatus of claim 6, wherein the inductance values of the first and second inductors are in the microhenry range.
8. The apparatus of any of claims 4-7, wherein the first short-circuit protection module further comprises:
a chopper circuit connected between the first positive port and the first negative port of the first short-circuit protection module.
9. The apparatus of claim 8, the chopper circuit comprising:
a third switching tube, a first port of which is connected with the first positive electrode port of the first short-circuit protection module;
and one end of the chopper resistor is connected with the second port of the third switching tube, and the other end of the chopper resistor is connected with the first negative electrode port of the first short-circuit protection module.
10. The apparatus of claim 9, the chopper circuit further comprising:
and a first port of the fourth switching tube is connected with a second port of the third switching tube, and a second port of the fourth switching tube is connected with a first negative port of the first short-circuit protection module.
11. The apparatus of claim 8 or 9, wherein the chopper circuit further comprises:
and the anode of the clamping diode is connected with the first cathode port of the first short-circuit protection module, and the cathode of the clamping diode is connected with the second port of the third switching tube.
12. The apparatus of any of claims 8-10, wherein the first direct current capacitor is integrated in the chopper circuit.
13. The device according to any one of claims 4-12, wherein each switching tube comprises a switching section and a freewheeling diode connected in anti-parallel with the switching section.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911088716.0A CN112787313B (en) | 2019-11-08 | 2019-11-08 | Ship direct-current power grid short-circuit protection device |
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| CN201911088716.0A CN112787313B (en) | 2019-11-08 | 2019-11-08 | Ship direct-current power grid short-circuit protection device |
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| CN112787313B CN112787313B (en) | 2022-03-29 |
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