CN113572147B - DC power supply and distribution system - Google Patents
DC power supply and distribution system Download PDFInfo
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- CN113572147B CN113572147B CN202110833066.9A CN202110833066A CN113572147B CN 113572147 B CN113572147 B CN 113572147B CN 202110833066 A CN202110833066 A CN 202110833066A CN 113572147 B CN113572147 B CN 113572147B
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- 238000004804 winding Methods 0.000 claims abstract description 113
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- 230000009977 dual effect Effects 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 7
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- 230000007935 neutral effect Effects 0.000 description 4
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- 238000011160 research Methods 0.000 description 2
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
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- 239000008358 core component Substances 0.000 description 1
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- 238000004146 energy storage Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/08—Three-wire systems; Systems having more than three wires
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
- H02J1/12—Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/14—Balancing the load in a network
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
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Abstract
The invention discloses a direct current power supply and distribution system. The direct current power supply and distribution system adopts a generator set to provide alternating current, forms bipolar direct current of a three-wire system through a rectifier, and selects a corresponding propulsion inverter according to a load to be connected to direct current buses with different polarities, so that electric loads with different voltage levels are realized. In addition, through connecting the two windings of the double-winding propulsion motor to the bipolar direct current bus through the corresponding propulsion inverter, voltage signals on the bipolar direct current bus are monitored in real time, and on the premise that the output power of the double-winding propulsion motor is met, the output power of the propulsion inverter is regulated, so that the power consumption load of the bipolar direct current bus tends to be balanced.
Description
Technical Field
The invention relates to the technical field of direct current power supply and distribution, in particular to a direct current power supply and distribution system.
Background
In recent years, direct current power supply and distribution systems have been rapidly developed and applied, wherein the systems can be classified into a unipolar system and a bipolar system according to polarities of the power supply and distribution systems. Compared with a unipolar direct current power supply system, the bipolar direct current power supply system can provide richer voltage levels, larger power levels and has redundant power supply capability.
For example, patent CN109755934a proposes a bipolar dc power supply device applied to a dc power distribution system, to implement high-voltage dc power distribution transmission and low-voltage dc power distribution power supply. For another example, patent CN109755955a proposes an ac-DC converter control strategy suitable for a bipolar DC micro-grid, so as to maintain the DC power supply voltage and adjust the droop characteristic of the bipolar DC micro-grid according to the droop characteristics of the two polarity DC power supplies and the neutral point unbalance of the DC bus side of the rectifier and the DC/DC (direct current/direct current) converter.
However, it is found through researches that, like the bipolar dc power supply device provided in CN109755934a, the power conversion unit in the device needs to distribute the power consumption on the bipolar bus according to the power characteristics during design, otherwise, the problem of unbalanced power of the bipolar dc bus will occur, and the efficiency of the power conversion unit is reduced. Also, the control strategy for ac-DC and DC-DC converters, as provided in patent CN109755955a, requires that both sides of the DC bus must be provided with a fully controlled rectifier and DC/DC converter, which is costly.
In view of this, how to realize the high-efficiency power supply requirement of satisfying a plurality of direct-current voltage levels of the direct-current power grid and solve the problem of the load balance control of the direct-current bus under the condition of unbalanced load becomes an important research project of related researchers.
Disclosure of Invention
The embodiment of the invention provides a direct current power supply and distribution system, which adopts a generator set to provide alternating current, forms three-wire bipolar direct current through a rectifier, and selects a corresponding propulsion inverter according to a load to be connected to direct current buses with different polarities, so that the electric loads with different voltage levels are realized. In addition, through connecting the two windings of the double-winding propulsion motor to the direct current buses with different polarities through the corresponding propulsion inverters, voltage signals on the bipolar direct current buses are monitored in real time, and on the premise that the output power of the double-winding propulsion motor is met, the output power of the propulsion inverters is regulated, so that the power consumption load of the bipolar direct current buses tends to be balanced.
The embodiment of the invention provides a direct current power supply and distribution system, which comprises: the power generation unit, the rectifier and the direct current bus; the generator set is a double-winding generator, each winding is connected to a corresponding rectifier, and the generator set is used for providing alternating current; the rectifier is connected to direct current buses with different polarities and is used for converting alternating current into direct current; the direct current bus is a bus with more than three wires, and is used for forming direct current power supplies with different voltage grades according to direct currents with different polarities so as to supply power to a load.
Optionally, when the direct current bus is a three-wire system, a first path of rectification output voltage is arranged between the first stage and the second stage, a second path of rectification output voltage is arranged between the second stage and the third stage, and two paths of rectification output voltages are arranged between the first stage and the third stage.
Optionally, the direct current power supply and distribution system further comprises a propulsion inverter and a propulsion motor, wherein two windings of the propulsion motor are connected to direct current buses with different polarities through the corresponding propulsion inverter; the propulsion inverter is used for collecting voltage signals of the direct current buses in real time, and when the sum of the output power of two propulsion inverters connected with the propulsion motor is larger than or equal to the output power of the propulsion motor, the output power of the propulsion inverter is regulated so that the power loads of the direct current buses with different polarities tend to be balanced.
Optionally, the boost inverter is configured to obtain the adjustment variable quantity of the output power according to the voltage signal of the dc bus and through a voltage-power droop characteristic curve.
Optionally, the propulsion inverter includes a propulsion inverter controller disposed inside the propulsion inverter for adjusting output power of the propulsion inverter so that power loads of the dc buses with different polarities tend to be balanced.
Optionally, the operation modes of the propulsion motor include a motor mode and a generator mode; when the working mode of the propulsion motor is a motor mode, the propulsion motor is used as a load of a direct current power supply and distribution system; when the working mode of the propulsion motor is a generator mode, the propulsion motor is used as a power supply to supply power to the direct current bus.
Optionally, when the operation mode of the propulsion motor is a generator mode, the two windings of the propulsion motor are each supplied with power to a dc bus of different polarity through a respective propulsion inverter.
Optionally, the rectifier is full-control rectification or uncontrolled rectification.
Optionally, the generator sets are multiple and are used for redundant power supply.
Optionally, the dc power supply and distribution system further includes a bus switch, where when the bus switch is in a closed state, dc buses located at two sides of the bus switch are working together; when the bus switch is in an off state, the direct current buses positioned at the two sides of the bus switch work independently.
The direct current power supply and distribution system provided by the embodiment of the invention can realize simultaneous power supply of bipolar direct current power supplies with different voltage classes, thereby meeting the load power supply requirements of different voltage classes and different power classes. In addition, the electric load of the bipolar direct current bus tends to be balanced on the premise of not additionally adding the power conversion device. Further, the propulsion inverter controller configured by the dual winding motor can independently implement the power load balancing function to avoid reliance on a centralized control system. In addition, the respective windings of the double-winding propulsion motor are supplied with power to direct current buses with different polarities, so that redundant power supply is formed with bipolar power supply of the double-winding generator. Besides, the double-winding propulsion motor can be used as a ship shaft motor, can also be used in a generator mode besides a motor mode, so that bipolar power supply is realized as a generator, the redundancy of power supply is improved, and different double-winding propulsion motors and two windings of the double-winding propulsion motor can be independently controlled.
Drawings
The technical solution and other advantageous effects of the present invention will be made apparent by the following detailed description of the specific embodiments of the present invention with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a dc power supply and distribution system according to an embodiment of the invention.
Fig. 2 is a schematic block diagram of control of load uniformity of a bipolar dc bus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically connected, electrically connected or can be communicated with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Fig. 1 is a schematic diagram of a dc power supply and distribution system according to an embodiment of the invention. Fig. 2 is a schematic block diagram of control of load uniformity of a bipolar dc bus according to an embodiment of the present invention.
Referring to fig. 1-2, a dc power supply and distribution system 1000 is provided according to an embodiment of the present invention. The dc power supply and distribution system 1000 includes: genset 110, rectifier 120, and dc bus 130. The generator set 110 is a double-winding generator 110 (note that, the reference numerals of the double-winding generator are used as the reference numerals of the generator set), each winding (not labeled in the figure) is connected to a corresponding rectifier 120, and the generator set 110 is used for providing alternating current; the rectifier 120 is connected to the dc buses 130 with different polarities, and the rectifier 120 is used for converting ac power into dc power; and the dc bus 130 is a bus with three or more wires, and the dc bus 130 is used for forming dc power sources with different voltage levels according to dc power with different polarities to supply power to a load. In addition, the dc power supply and distribution system 1000 further includes a propulsion inverter 140 and a propulsion motor 150, and two windings of the propulsion motor 150 are connected to dc buses 130 of different polarities through the respective propulsion inverters 140; the propulsion inverter 140 is configured to collect the voltage signal of the dc bus 130 in real time, and adjust the output power of the propulsion inverter 140 when the sum of the output powers of the two propulsion inverters 140 connected to the propulsion motor 150 is greater than or equal to the output power of the propulsion motor 150, so that the power loads of the dc buses 130 with different polarities tend to be balanced.
The direct current power supply and distribution system provided by the embodiment of the invention can realize simultaneous power supply of bipolar direct current power supplies with different voltage classes, thereby meeting the load power supply requirements of different voltage classes and different power classes. In addition, the electric load of the bipolar direct current bus tends to be balanced on the premise of not additionally adding the power conversion device. Further, the propulsion inverter controller configured by the dual winding motor can independently implement the power load balancing function to avoid reliance on a centralized control system. In addition, the respective windings of the double-winding propulsion motor are supplied with power to direct current buses with different polarities, so that redundant power supply is formed with bipolar power supply of the double-winding generator. Besides, the double-winding propulsion motor can be used as a ship shaft motor, can also be used in a generator mode besides a motor mode, so as to be used as a generator to realize bipolar power supply, thereby improving the redundancy of the whole power grid power supply, and different double-winding propulsion motors and two windings thereof can be independently controlled.
The various components of the dc power supply and distribution system 1000 are described in further detail below in conjunction with the figures.
As shown in fig. 1, in this embodiment, the dc power supply and distribution system 1000 includes: genset 110, rectifier 120, dc bus 130, bus switch 180, propulsion inverter 140, propulsion motor 150, and daily inverter 170. It should be noted that, the power grid described below refers to the dc bus 130 and/or the propulsion inverter 140 for power distribution. The power supply means refers to a double winding generator 110 and a rectifier 120 for supplying power. Both the propulsion inverter 140 and the rectifier 120 (limited to fully controlled) have droop characteristic control functions. The grid load level can thus be reflected from the grid voltage according to the droop characteristic.
Specifically, genset 110 is a dual-winding generator 110, and genset 110 is driven to operate by prime mover 160. The two windings of the generator set 110 are connected to rectifiers 120, respectively. Genset 110 is two or more for redundant power supply. In this embodiment, the two power generating units 110 may be in a primary-standby operation mode or a load sharing operation mode.
The rectifier 120 is connected to the dc buses 130 of different polarities, and is used to convert the ac power provided by the generator set 110 into dc power and transmit the dc power to the dc buses 130 of different polarities. The rectifier 120 may be one of a diode, a thyristor, and an insulated gate bipolar transistor. Different rectifying modes are selected correspondingly according to the voltage requirement of the load. For example, by means of diode rectification, costs can be saved. For another example, the voltage class of the dc bus can be made wider by means of thyristor (or thyristor) or Insulated Gate Bipolar Transistor (IGBT) rectification. If diode rectification is adopted, only the anode and the cathode are provided. If an insulated gate bipolar transistor rectifying mode is adopted, positive, negative and neutral can be provided to realize bipolar three-wire system. Further, the rectifier 120 may be full or uncontrolled rectification. The full-control rectification has wide adjustable voltage range and high cost; the voltage value of uncontrolled rectification is constant and the cost is low. In this embodiment, the rectifier 120 adopts a fully controlled rectification mode.
The output of each double-winding generator 110 is connected to two rectifiers 120. That is, the two windings of each two-winding generator 110 are each connected to one rectifier 120. In this embodiment, two dual-winding generators 110 are connected to four rectifiers 120. Each rectifier 120 converts alternating current flowing through a corresponding winding of the two-winding generator 110 into direct current and transmits the direct current to the direct current bus 130 of different polarity.
In this embodiment, the dc bus 130 is a three-wire system, which includes a first stage, a second stage, and a third stage. The first stage, namely the P stage, is a positive electrode, the second stage, namely the O stage, is a neutral electrode (or called a common ground), and the third stage, namely the N stage, is a negative electrode. Thus, bipolar as described herein refers to both polarities P-O, O-N. As shown in fig. 1, two windings of the double-winding generator 110 are respectively connected to one rectifier 120, the positive output end of the first rectifier 120 is connected to the positive electrode of the dc bus 130, the negative output end of the second rectifier 120 is connected to the negative electrode of the dc bus 130, and the negative output end of the first rectifier 120 and the positive output end of the second rectifier 120 are connected to the neutral electrode of the dc bus 130, i.e., the two rectifiers 120 are connected in series to form a bipolar dc bus in three wires.
The first path of rectification output voltage is arranged between the first stage and the second stage of the bipolar direct current bus of the three-wire system, the second path of rectification output voltage is arranged between the second stage and the third stage, and the two paths of rectification output voltage are arranged between the first stage and the third stage. Namely, a first path of rectification output voltage is arranged between the P-O stages, a second path of rectification output voltage is arranged between the O-N stages, and two paths of rectification output voltage are arranged between the P-N stages. Different voltage levels can be formed by a combination between different stages (between two by two). For example, a bipolar high-low voltage or a bipolar equivalent voltage may be combined.
The dc bus 130 is used for forming dc power sources with different voltage levels according to dc power with different polarities to supply power to a load. The load may be the propulsion motor 150 shown in fig. 1, or other fans, pumps, or daily loads.
The different windings of the double-winding generator 110 are connected to the rectifier 120 to be connected to three-wire DC buses with different polarities, so that the bipolar DC power supplies with different voltage levels can supply power simultaneously, and the load power supply requirements of different voltage levels and different power levels can be met. It should be noted that, if conventional power is provided, the dc power supply and distribution system 1000 of the present invention may be used to supply power to a load through the combination of the generator set 110, the rectifier 120 and the dc bus 130, without having to provide a propulsion inverter 140 and a propulsion motor 150 as described below. Of course, the dc power supply and distribution system 1000 may also be powered by the genset 110, the rectifier 120, the dc bus 130, the propulsion inverter 140, and the propulsion motor 150, as described in detail below.
In this embodiment, the dc power supply and distribution system 1000 further includes a propulsion inverter 140 and a propulsion motor 150. Propulsion inverter 140 and propulsion motor 150 may be considered an integral unit and serve as the core components of a dc power supply and distribution system in an electric propulsion marine propulsion system. Wherein the propulsion inverter 140 is selected accordingly based on the supply voltage and power of the load. For example, taking a bipolar direct current bus with high and low voltage as an example, if the load is a propulsion motor with rated voltage of 690V, a high-power inverter is selected to be connected to the P-O stage of the direct current bus; if the load is a daily load (e.g., lighting, heating, etc.) rated at 380V, then a low power inverter is selected to connect to the O-N stage of the dc bus.
The propulsion motor 150 is a dual-winding propulsion motor 150 (note that, the numbers of dual-winding propulsion motors are used herein to refer to the numbers of propulsion motors). The two windings of the two-winding propulsion motor 150 are connected to dc bus 130 of different polarity through respective propulsion inverters 140. Specifically, the two stator windings of the dual winding propulsion motor 150 are connected to the ac terminals of the propulsion inverter 140, and the dc terminals of the propulsion inverter 140 are connected to dc bus bars 130 of different polarities. In the present embodiment, the number of the two-winding propulsion motors 150 is two, and each two-winding propulsion motor 150 is connected to two propulsion inverters 140, respectively.
The modes of operation of the dual winding propulsion motor 150 include a motor mode and a generator mode. Depending on the requirements of the dc power distribution system 1000, a plurality of dual winding propulsion motors 150 are provided, each dual winding propulsion motor 150 being selectively operable in either a motor mode or a generator mode depending on the particular operating requirements.
When the operation mode of the dual-winding propulsion motor 150 is the motor mode, the dual-winding propulsion motor 150 acts as a load for the dc power supply and distribution system 1000. When the operation mode of the dual-winding propulsion motor 150 is the generator mode, the dual-winding propulsion motor 150 serves as a power source to supply power to the dc bus 130 of different polarities. That is, when the two-winding propulsion motor 150 is used as a motor, the propulsion inverter 140 has an inverter function and outputs in the forward direction. When the ship brakes and the double-winding propulsion motor 150 is used as a generator, the propulsion inverter 140 is operated in a rectifying state in a reverse direction and outputs in a reverse direction. Further, when the operation mode of the dual-winding propulsion motor 150 is the generator mode, the two windings of the dual-winding propulsion motor 150 are each supplied to the dc bus 130 of different polarity through the corresponding propulsion inverter 140.
In some embodiments, when the dual-winding propulsion motor 150 is operating in a motor mode, two propulsion inverters 140 connected to the dual-winding propulsion motor 150 collect the voltage signal of the dc bus 130 in real time, and when the sum of the output powers of the two propulsion inverters 140 is greater than or equal to the output power of the dual-winding propulsion motor 150, the two propulsion inverters 140 may each adjust their own output power so that the electrical loads of the dc buses 130 of different polarities tend to equalize. That is, when the dual-winding propulsion motor 150 is operating in the motor mode, the power of the dual-winding propulsion motor 150 is equal to the sum of the two paths of electrical energy obtained through the two stator windings of the dual-winding propulsion motor 150. While maintaining the output power of the dual winding propulsion motor 150 unchanged, when one of the two powers generated by the two stator windings is increased, the other power is correspondingly decreased, so as to adjust the load balance of the corresponding dc bus 130.
Further, the boost inverter 140 is configured to obtain an adjustment variable quantity of the output power according to the voltage signal of the dc bus 130 and through a voltage-power droop characteristic curve and a corresponding preset algorithm, so as to adjust the output power of the boost inverter accordingly, so that the power loads of the dc buses 130 with different polarities tend to be balanced. The voltage-power droop characteristic refers to the characteristic of the propulsion inverter, the output power and the output voltage of the propulsion inverter show a droop trend, the propulsion inverter detects the output voltage of the propulsion inverter, the output power can be obtained through the droop characteristic, and then the load electric quantity on different polarities of the three-wire system direct current bus is obtained.
The droop characteristics of the output voltage frequency and amplitude of the boost inverter are:
ω- ω 0 = -k p (P-P 0 )
U- U 0 = -k q (Q-Q 0 )
wherein omega 0 ，U 0 The rated angular frequency and the rated voltage of the output of the propulsion inverter are respectively. k (k) p ，k q Is an inverter droop coefficient. And P and Q are respectively the active power and the reactive power which are actually output by the propulsion inverter. P (P) 0 ，Q 0 The propulsion inverter is rated for active and reactive power, respectively.
Therefore, the dc power supply and distribution system 1000 of the present invention is connected to the dc buses 130 with different polarities through the two windings of the dual-winding propulsion motor 150 via the corresponding propulsion inverter 140, so as to monitor the voltage signals of the bipolar dc buses in real time, and adjust the output power of the propulsion inverter 140 on the premise of meeting the output power of the dual-winding propulsion motor 150, thereby realizing that the power load of the bipolar dc buses tends to be balanced without adding an additional power conversion device.
The load balancing control of the bipolar dc bus will be further described below with reference to fig. 2.
Referring to fig. 2, two propulsion inverters 140 collect voltage signals of a bipolar dc bus to obtain a first voltage Vdc1 and a second voltage Vdc2, respectively; then, respectively obtaining a first power P1 and a second power P2 through a voltage-power droop curve and a corresponding preset algorithm; then, through difference calculation (S/2 shown in fig. 2), a first adjustment variation Δp1 and a second adjustment variation Δp2 can be obtained, where the first adjustment variation Δp1 and the second adjustment variation Δp2 are target output power values of the two propulsion inverters 140 respectively; the first adjustment variable Δp1 and the second adjustment variable Δp2 are used as input parameters of current loop control together with the rotation speed feedback of the double-winding propulsion motor 150, so as to adjust the output power values of the two propulsion inverters 140 until the power loads of the bipolar direct current buses tend to be balanced.
With continued reference to fig. 1, in this embodiment, the dc power supply and distribution system 1000 includes two dual winding propulsion motors 150, each dual winding propulsion motor 150 having two windings. The two windings of the same two-winding propulsion motor 150 are independently adjustable, as are the two-winding propulsion motors 150. If the dc bus 130 of the power grid is unbalanced, all propulsion inverters 140 (here, four propulsion inverters) connected to the two-winding propulsion motors 150 automatically adjust the output power to balance the load of the dc bus 130.
Further, the load balancing function may be implemented by an inverter controller (not shown) disposed inside the propulsion inverter 140. The inverter controller can be a PCB control circuit board, and can independently realize the function of balancing the power load so as to avoid depending on a centralized control system.
Of course, in other embodiments, the power may be trimmed for each path at the beginning of the grid design, or a power change device (such as bidirectional DC) and an energy storage unit may be used to transfer the electric energy of each polarity. Compared with the methods, by using the propulsion inverter 140 and the propulsion motor 150, the polarity loads can be dynamically balanced in real time, and an additional power conversion device is not needed, so that the equipment cost is saved.
In some embodiments, when the dual winding propulsion motor 150 is operating in a generator mode, the dual winding propulsion motor 150 may act as a primary power source to power the dc bus 130. Further, the two windings of the two-winding propulsion motor 150 are each powered to a dc bus 130 of different polarity by a respective propulsion inverter 140 to effect reverse power to the dc bus by the two-winding propulsion motor. The two propulsion inverters 140 connected to the dual winding propulsion motor 150 achieve grid-connected power to the dc bus 130 by monitoring the voltage signal of the dc bus 130 in real time. By the design, bipolar power supply of the double-winding propulsion motor in a generator mode can be realized, and therefore the redundancy of power supply of the whole power grid is improved. Further, under normal conditions, the double-winding generator continuously generates power, and when the double-winding propulsion motor is used as a generator, only the power is additionally supplied to the direct current bus part; when the double-winding generator fails and the ship brakes in a decelerating way, the double-winding propulsion motor can independently provide power for the whole power grid in a short time when the double-winding propulsion motor is used as a generator.
In addition, the two propulsion inverters 140 may each adjust their own reverse output power according to a preset power-voltage sag characteristic. Further, the boost inverter 140 detects its own output power according to the power-voltage sag characteristic curve and a preset algorithm to obtain an output voltage amplitude and frequency, and then fine-adjusts its output voltage amplitude and frequency in an inverted phase to achieve reasonable distribution of output active and reactive power.
With continued reference to fig. 1, in this embodiment, the dc power supply and distribution system 1000 further includes a bus switch 180, where the dc buses 130 located at two sides of the bus switch 180 are used to work together when the bus switch 180 is in a closed state; when the bus switch 180 is in an off state, the dc buses 130 located at both sides of the bus switch 180 operate independently. That is, the two-winding generator 110 located at one side of the bus switch 180 drives the corresponding two-winding propulsion motor 150, and the two-winding generator 110 located at the other side of the bus switch 180 drives the corresponding two-winding propulsion motor 150 to operate independently.
When the dc bus 130 corresponding to one of the two sides of the bus switch 180 or the power distribution device or power supply device corresponding to the dc bus 130 fails, the bus switch 180 may be set to be turned off, so that the fault circuit is isolated from the power grid, and maintenance and overhaul are facilitated.
As shown in fig. 1, in the present embodiment, the dc power supply and distribution system 1000 further includes a daily inverter 170, an LCL filter 191, and an isolation transformer 192. The daily inverter 170 supplies ac power to a load for a marine power grid application (for short, marine) and is connected to the dc bus 130 of a corresponding polarity according to a supply voltage level of the load. LCL filter 191 is an inductor-capacitor-inductor filter. The isolation transformer 192 is a transformer with electrical isolation between the input winding and the output winding for isolating dangerous voltages.
According to the direct current power supply and distribution system, the generator set is adopted to provide alternating current, the three-wire bipolar direct current is formed through the rectifier, and the corresponding propulsion inverter is selected according to the load to be connected to buses with different polarities, so that the bipolar direct current power supplies with different voltage levels can supply power simultaneously, and further the load power supply requirements of different voltage levels and different power levels can be met. In addition, the two windings of the double-winding propulsion motor are respectively connected to the direct current buses with different polarities through the corresponding propulsion inverters so as to monitor voltage signals of the bipolar direct current buses in real time, and on the premise of meeting the output power of the double-winding propulsion motor, the output power of the propulsion inverters is regulated, so that the power consumption load trend of the bipolar direct current buses is balanced on the premise of not additionally increasing a power conversion device. Further, the propulsion inverter controller configured by the dual winding motor can independently implement the power load balancing function to avoid reliance on a centralized control system. In addition, the respective windings of the double-winding propulsion motor are supplied with power to direct current buses with different polarities, so that redundant power supply is formed with bipolar power supply of the double-winding generator. Besides, the double-winding propulsion motor can be used as a ship shaft motor, can also be used in a generator mode besides a motor mode, so as to be used as a generator to realize bipolar power supply, thereby improving the redundancy of the whole power grid power supply, and different double-winding propulsion motors and two windings thereof can be independently controlled.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.
The above describes in detail a dc power supply and distribution system provided by the embodiment of the present invention, and specific examples are applied to illustrate the principle and implementation of the present invention, where the above description of the embodiment is only used to help understand the technical solution and core idea of the present invention; those of ordinary skill in the art will appreciate that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (7)
1. A direct current power supply and distribution system, comprising: the power generation unit, the rectifier and the direct current bus; the generator set is a double-winding generator, each winding is connected to a corresponding rectifier, and the generator set is used for providing alternating current; the rectifier is connected to direct current buses with different polarities and is used for converting alternating current into direct current; the direct current bus is a bus with more than three wires, and is used for forming direct current power supplies with different voltage classes according to direct currents with different polarities so as to supply power to a load;
the motor also comprises a propulsion inverter and a propulsion motor, wherein two windings of the propulsion motor are connected to direct current buses with different polarities through the corresponding propulsion inverter; the propulsion inverter is used for collecting voltage signals of the direct current bus in real time; when the sum of the output power of the two propulsion inverters connected with the propulsion motor is larger than or equal to the output power of the propulsion motor, the two propulsion inverters obtain corresponding power through a voltage-power sagging characteristic curve according to a voltage signal acquired in real time, and then the adjustment variable quantity of the corresponding output power is obtained through difference calculation, and the adjustment variable quantity and the rotating speed feedback of the propulsion motor are used as input parameters of current loop control, so that the output power of the propulsion inverters is correspondingly adjusted, and the power loads of direct current buses with different polarities tend to be balanced.
2. The direct current power supply and distribution system according to claim 1, wherein when the direct current bus is a three-wire system, a first path of rectified output voltage is arranged between the first stage and the second stage, a second path of rectified output voltage is arranged between the second stage and the third stage, and two paths of rectified output voltage are arranged between the first stage and the third stage.
3. The dc power supply and distribution system according to claim 1, wherein the propulsion inverter includes a propulsion inverter controller disposed inside the propulsion inverter for adjusting the output power of the propulsion inverter so that the power loads of the dc buses of different polarities tend to be balanced.
4. The direct current power supply and distribution system of claim 1, wherein the operating modes of the propulsion motor include a motor mode and a generator mode; when the working mode of the propulsion motor is a motor mode, the propulsion motor is used as a load of a direct current power supply and distribution system; when the working mode of the propulsion motor is a generator mode, the propulsion motor is used as a power supply to supply power to the direct current bus.
5. The direct current power supply and distribution system according to claim 1, wherein the rectifier is full or uncontrolled rectification.
6. The direct current power supply and distribution system according to claim 1, wherein the number of the generator sets is plural for redundant power supply.
7. The direct current power supply and distribution system according to claim 1, further comprising a bus switch for co-operating with the direct current buses on both sides of the bus switch when the bus switch is in a closed state; when the bus switch is in an off state, the direct current buses positioned at the two sides of the bus switch work independently.
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