CN106628096B - Shore power system and grid-connected control method thereof - Google Patents
Shore power system and grid-connected control method thereof Download PDFInfo
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- CN106628096B CN106628096B CN201610991259.6A CN201610991259A CN106628096B CN 106628096 B CN106628096 B CN 106628096B CN 201610991259 A CN201610991259 A CN 201610991259A CN 106628096 B CN106628096 B CN 106628096B
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- power
- power supply
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63J—AUXILIARIES ON VESSELS
- B63J3/00—Driving of auxiliaries
- B63J3/04—Driving of auxiliaries from power plant other than propulsion power plant
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63J—AUXILIARIES ON VESSELS
- B63J3/00—Driving of auxiliaries
- B63J3/04—Driving of auxiliaries from power plant other than propulsion power plant
- B63J2003/043—Driving of auxiliaries from power plant other than propulsion power plant using shore connectors for electric power supply from shore-borne mains, or other electric energy sources external to the vessel, e.g. for docked, or moored vessels
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/10—Flexible AC transmission systems [FACTS]
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
The invention relates to a shore power system, which comprises a shore power grid, a variable frequency power supply, a grid-connected switch, a generator switch and a ship power generation system, wherein the variable frequency power supply comprises a multi-winding transformer and at least one power module, the input side of the power module is connected with a low-voltage side winding of the multi-winding transformer, and the output sides of the power module are mutually cascaded; the shore power system based grid-connected control method can avoid the phenomenon of reverse power of a ship power generation system, greatly improve the success rate of grid connection, and is safe and reliable and low in cost.
Description
Technical Field
The invention relates to the field of power electronic power conversion, in particular to a shore power system applied to a port and wharf and a grid-connected control method thereof.
Background
The shore power system is applied to a shore power access technology, and means that a generator on a ship is stopped to be used and a land power supply is used for supplying power during the berthing of the ship. The variable frequency power supply is the core of a shore power access system, and is responsible for converting a 50HZ alternating current power supply on the shore into a 60HZ alternating current power supply required by a ship through an AC-DC-AC variable frequency link, when the ship power generation system is combined with the shore power system, namely, a grid-connected switch is turned on after the voltage of the ship power generation system detecting the shore power system meets the condition, the process of combining the ship power generation system into the shore power system is realized, great impact can be generated at the moment, impact current can cause grid-connected failure or cause reverse power generation, when the reverse power occurs, the power direction of a generator flows to a motor side from a system side, active power is absorbed from the system at the moment, and the occurrence of the reverse power can cause adverse effect on the motor.
disclosure of Invention
Aiming at the technical problems, the invention aims to provide a shore power system and a grid-connected control method thereof, which can reduce the impact current when a ship power generation system and the shore power system are combined, avoid the reverse power phenomenon and improve the grid-connected success rate.
The invention designs a shore power system, which comprises a shore power grid, a variable frequency power supply, a grid-connected switch, a generator switch and a ship power generation system, wherein the variable frequency power supply comprises a multi-winding transformer and at least one power module, the input side of the power module is connected with a low-voltage side winding of the multi-winding transformer, and the output sides of the power module are mutually cascaded; the power module comprises a rectifying unit and an inverting unit.
the power module further comprises a quick switch, an absorption resistor and a bypass switch, the quick switch is connected with the absorption resistor in series, the series connection is connected with the direct current output side of the rectifying unit in parallel, and the bypass switch is connected with the output side of the inverting unit in parallel.
the rectifying unit of the power supply module comprises a three-phase rectifying bridge, and the three-phase rectifying bridge is composed of an uncontrollable power semiconductor device.
The inversion unit of the power supply module can convert direct current voltage into alternating current voltage and is composed of controllable power semiconductor devices.
The fast switch is composed of a power semiconductor device, the power semiconductor device can be an active power semiconductor device, and the on and off of the active power semiconductor device need to control a trigger signal; or a passive power semiconductor device, which is automatically turned on when detecting that the direct current exceeds a certain value without controlling a trigger signal.
The invention also comprises a grid-connected control method of the shore power system, which comprises the following steps:
1) when the variable frequency power supply receives a grid-connected instruction, outputting alternating-current voltage with the same amplitude, the same frequency and the same phase as the ship-side voltage according to the ship-side voltage as a reference;
2) the ship side power generation system detects the amplitude, frequency and phase of ship side voltage and shore side voltage, and when the amplitude and frequency of the ship side voltage are slightly higher than the shore side voltage and the phase difference is smaller than a certain value, the grid-connected switch is switched on;
3) when the variable frequency power supply detects that the grid-connected switch is closed, switching a control target, enabling the variable frequency power supply to take output current or power as the control target, setting the control target of the output current or the output power of the variable frequency power supply to be 0, detecting the direct current voltage of the power supply module during the period, and closing the quick switch when the power supply module detects that the direct current voltage exceeds a first threshold value; when the direct-current voltage exceeds a second threshold value, all power semiconductor devices of the inversion unit are turned off, and then the bypass switch is closed;
4) After the output current of the variable frequency power supply is smaller than a first allowable value, gradually adjusting the output voltage of the variable frequency power supply to gradually increase the output power of the variable frequency power supply and gradually reduce the output power of the ship power generation system;
5) When the ship power generation system detects that the current flowing through the generator switch is smaller than a second allowable value, the generator switch is disconnected;
6) and when the variable frequency power supply detects that the generator switch is disconnected, switching the control strategy to enable the variable frequency power supply to take the output voltage as a control target.
And the output current or the output power of the variable frequency power supply is the current or the power flowing through the grid-connected switch.
wherein the first allowable value is not more than 10% of the output current rating of the variable frequency power supply, and the second allowable value is not more than 20% of the output current rating of the variable frequency power supply.
Wherein the first threshold is lower than a second threshold.
Compared with the prior art, the shore power system and the grid-connected control method have the following technical effects:
(1) according to the shore power system, the variable frequency power supply is provided with the fast switch, the absorption resistor and the bypass switch, impact power in the grid connection process can be absorbed in the grid connection process, when the impact power exists, energy can be accumulated on the direct current side of each power supply module, direct current voltage can rise, at the moment, surplus energy is led into the absorption resistor through the fast switch to absorb the surplus energy, when the direct current voltage continues to rise, the bypass switch can be closed, the power supply modules are bypassed, the modules are prevented from being damaged due to overvoltage, and the shore power system serves as backup protection. Through the cooperation of the fast switch, the absorption resistor and the bypass switch logic, the impact power in the grid connection process is absorbed to the greatest extent, and the safe work of the variable frequency power supply can be ensured through double protection.
(2) According to the shore power system and the grid-connected control method, the ship-side voltage amplitude and the frequency output by the ship-side power generation system are slightly higher than the shore-side voltage before grid connection, so that the impact power direction of grid connection is from the ship side to the shore side, and meanwhile, the shore power variable frequency power supply is provided with an energy absorption loop, so that the impact power can be absorbed, the phenomenon of inverse power of the ship power generation system is avoided, and the success rate of grid connection is greatly improved.
(3) According to the shore power system and the grid-connected control method, the variable frequency power supply switches the control strategy according to the state of the grid-connected switch and the state of the generator switch, the impact current can be effectively limited through the switching of the control strategy in the grid-connected process, the grid-connected success rate and the grid-connected safety are improved, the control strategy is switched through the judgment of the switch state, and compared with a communication mode, the shore power system is quicker and more accurate, the system complexity is lower, and the cost is lower.
drawings
FIG. 1 is a schematic diagram of the design of a shore power system;
FIG. 2 is a schematic diagram of a variable frequency power supply according to the present invention;
Fig. 3 is a schematic structural diagram of a power module in the present invention.
The system comprises a shore power grid 1, a variable frequency power supply 2, a grid-connected switch 3, a generator switch 4, a ship power generation system 5, a multi-winding phase-shifting transformer 6, a power supply module 7, a rectification unit 8, a quick switch 9, an absorption resistor 10, an inversion unit 11 and a bypass switch 12.
Detailed Description
the following description will explain embodiments of the present invention in further detail with reference to the accompanying drawings.
The shore power system comprises a shore power grid 1, a variable frequency power supply 2, a grid-connected switch 3, a generator switch 4 and a ship power generation system 5, and the connection mode is shown in figure 1.
the variable frequency power supply comprises a multi-winding phase-shifting transformer 6 and at least one power supply module 7, wherein the input side of the power supply module is connected with a low-voltage side winding of the multi-winding transformer, and the output sides of the power supply module are mutually cascaded; in the embodiment, the output sides of a plurality of power modules are cascaded with each other to form an a-phase converter chain, a B-phase converter chain and a C-phase converter chain, each phase contains the same number of power modules, and the topology is generally applied to a high-voltage frequency converter. The connection is shown in fig. 2.
As shown in fig. 3, the power supply module includes a rectifying unit 8 and an inverting unit 11. The power supply module further comprises a quick switch 9, an absorption resistor 10 and a bypass switch 12, wherein the quick switch is connected with the absorption resistor in series, the series connection is connected with the direct current output side of the rectifying unit in parallel, and the bypass switch is connected with the output side of the inverting unit in parallel. In this implementation, the ABC three-phase input in fig. 3 is connected to the ABC three-phase of the low-voltage side winding of the multi-winding phase-shifting transformer, the multi-winding phase-shifting transformer includes low-voltage windings having the same number as the power modules, and the phase between the windings is designed in a phase-shifting manner, so that it can be ensured that the input current harmonics meet the requirements.
In this embodiment, the rectifying unit of the power supply module is formed by a three-phase rectifying bridge, which is formed by an uncontrollable power semiconductor device: in the present embodiment, it is constituted by a diode; the inverter unit can convert the dc voltage into ac voltage, and is formed by a controllable power semiconductor device, in this embodiment, an IGBT, and the maximum voltage that the IGBT can withstand is 1700V.
In this embodiment, the fast switch and the absorption resistor form an energy absorption loop, where the fast switch may be a mechanical switch with a fast closing speed, or an electronic switch composed of power semiconductor devices, and the electronic switch may close the loop within 1ms, so as to quickly release the energy accumulated on the dc side, where the electronic switch may be an active power semiconductor device whose turn-on and turn-off needs to control a trigger signal, such as a thyristor or an IGBT; the device can also be a passive power semiconductor device, does not need to control a trigger signal, and automatically conducts when detecting that the direct current exceeds a certain value, such as a breakdown diode, which is usually used as an overvoltage protection device. The absorption resistor is usually a power resistor capable of bearing power impact for a short time, and in order to ensure the energy release speed, the resistance value is not too large, and is selected to be less than 5 ohms.
In this embodiment, the fast switch is composed of a breakdown diode, the breakdown diode has an operating voltage of 1300V, and the absorption resistor has a resistance value of 1 ohm.
The bypass switch in the invention adopts a mechanical switch capable of being quickly closed, and the whole power supply module can be bypassed. In this embodiment, each phase is configured with one redundant power module, for example, when the ac voltage of the marine power generation system is 11kV, the variable frequency power supply is configured with 10 power modules per phase, and in this embodiment, 11 power modules are configured, when one of the power modules fails or energy cannot be released due to abnormal breakdown of a diode in the grid connection process, and when the dc voltage is too high, the failed power module can be bypassed by a bypass switch to share the energy to the other power modules, so as to serve as system-level backup protection.
The invention also comprises a grid-connected control method of the shore power system, which comprises the following steps:
1) When the variable frequency power supply receives a grid-connected instruction, outputting alternating-current voltage with the same amplitude, the same frequency and the same phase as the ship-side voltage according to the ship-side voltage as a reference; in this example, the ship side voltage was 11kV,60 HZ.
2) The ship side power generation system detects the amplitude, frequency and phase of ship side voltage and shore side voltage, and when the amplitude and frequency of the ship side voltage are slightly higher than the shore side voltage and the phase difference is smaller than a certain value, the grid-connected switch is switched on; in the embodiment, after the shore power system voltage is established, the output voltage of the marine power generation system is controlled to be adjusted to 11.5kV and 60.3HZ, and when the phase difference is less than 10 degrees, the grid-connected switch is immediately switched on.
3) when the variable-frequency power supply detects that the grid-connected switch is closed, switching a control target, enabling the variable-frequency power supply to take output current or power as the control target, setting the control target of the output current or the output power of the variable-frequency power supply to be 0, detecting the direct-current voltage of the power supply module in the period, and conducting a breakdown diode when the power supply module detects that the direct-current voltage exceeds a first threshold value (1300V), so that energy is absorbed by an absorption resistor; if the energy is too large or the breakdown diode does not work normally, the direct-current voltage is still increased, when the direct-current voltage exceeds a second threshold value (1400V), all power semiconductor devices of the inversion unit are turned off, and then the bypass switch is closed; the module is bypassed, energy is absorbed by other power modules, and a direct current voltage of the power module is ensured not to exceed a safety value through a two-stage voltage threshold, wherein the maximum voltage which can be borne by the IGBT is 1700V in the embodiment, and a certain margin is reserved if the direct current voltage value is ensured not to exceed 1500V.
4) After the output current of the variable frequency power supply is smaller than the first allowable value, in this embodiment, smaller than 50A, the output voltage of the variable frequency power supply is gradually adjusted, so that the output power of the variable frequency power supply is gradually increased, and the output power of the ship power generation system is gradually decreased;
5) when the ship power generation system detects that the current flowing through the generator switch is smaller than a second allowable value, the second allowable value is 100A in the embodiment, and the generator switch is turned off; after step 5 is completed, the load of the marine power generation system has been completely transferred to the shore side power supply.
6) And when the variable frequency power supply detects that the generator switch is disconnected, switching the control strategy to enable the variable frequency power supply to take the output voltage as a control target. And the variable frequency power supply is switched back to a voltage control mode, and the output voltage is controlled to be 11kV and 60 HZ.
And finishing the whole grid connection process.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Claims (8)
1. A shore power system comprises a shore power grid, a variable frequency power supply, a grid-connected switch, a generator switch and a ship power generation system, wherein the variable frequency power supply comprises a multi-winding phase-shifting transformer and at least one power module, the input side of the power module is connected with a low-voltage side winding of the multi-winding transformer, and the output sides of the power module are mutually cascaded; the power module comprises a rectifying unit and an inverting unit, and is characterized in that: the power supply module further comprises a quick switch, an absorption resistor and a bypass switch, wherein the quick switch is connected with the absorption resistor in series, the series connection is connected with the direct current output side of the rectifying unit in parallel, and the bypass switch is connected with the output side of the inverting unit in parallel;
In the grid connection process, when the fact that the direct-current voltage of the power supply module rises and exceeds a first threshold value is detected, the fast switch is closed, the surplus energy is led into the absorption resistor through the fast switch to absorb the surplus energy, when the direct-current voltage continues to rise and exceeds a second threshold value, all power semiconductor devices of the inversion unit are turned off, and then the bypass switch is closed.
2. A shore power system according to claim 1, wherein: the rectifying unit of the power supply module comprises a three-phase rectifying bridge, and the three-phase rectifying bridge is composed of an uncontrollable power semiconductor device.
3. a shore power system according to claim 1, wherein: the inversion unit of the power supply module converts direct-current voltage into alternating-current voltage and is composed of a controllable power semiconductor device.
4. A shore power system according to claim 1, wherein: the fast switch is composed of a power semiconductor device, and when the power semiconductor device is an active power semiconductor device, the on and off of the active power semiconductor device need to control a trigger signal; when the power semiconductor device is a passive power semiconductor device, the power semiconductor device is automatically conducted when detecting that the direct current exceeds a certain value without controlling a trigger signal.
5. A grid-connected control method based on the shore power system of any one of claims 1 to 4, characterized in that: the control method comprises the following steps:
1) when the variable frequency power supply receives a grid-connected instruction, outputting alternating-current voltage with the same amplitude, the same frequency and the same phase as the ship-side voltage according to the ship-side voltage as a reference;
2) The ship side power generation system detects the amplitude, frequency and phase of ship side voltage and shore side voltage, and when the amplitude and frequency of the ship side voltage are slightly higher than the shore side voltage and the phase difference is smaller than a certain value, the grid-connected switch is switched on;
3) when the variable frequency power supply detects that the grid-connected switch is closed, switching a control target, enabling the variable frequency power supply to take output current or power as the control target, setting the control target of the output current or the output power of the variable frequency power supply to be 0, detecting the direct current voltage of the power supply module during the period, and closing the quick switch when the power supply module detects that the direct current voltage exceeds a first threshold value; when the direct-current voltage exceeds a second threshold value, all power semiconductor devices of the inversion unit are turned off, and then the bypass switch is closed;
4) After the output current of the variable frequency power supply is smaller than a first allowable value, gradually adjusting the output voltage of the variable frequency power supply to gradually increase the output power of the variable frequency power supply and gradually reduce the output power of the ship power generation system;
5) When the ship power generation system detects that the current flowing through the generator switch is smaller than a second allowable value, the generator switch is disconnected;
6) And when the variable frequency power supply detects that the generator switch is disconnected, switching the control strategy to enable the variable frequency power supply to take the output voltage as a control target.
6. the grid-connected control method of the shore power system according to claim 5, wherein: the output current or the output power of the variable frequency power supply is the current or the power flowing through the grid-connected switch.
7. The grid-connected control method of the shore power system according to claim 5, wherein: the first allowable value is not more than 10% of the rated output current of the variable-frequency power supply, and the second allowable value is not more than 20% of the rated output current of the variable-frequency power supply.
8. The grid-connected control method of the shore power system according to claim 5, wherein: the first threshold value is lower than a second threshold value.
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| CN201610991259.6A CN106628096B (en) | 2016-11-10 | 2016-11-10 | Shore power system and grid-connected control method thereof |
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| CN106628096B true CN106628096B (en) | 2019-12-06 |
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| CN107994612A (en) * | 2017-12-21 | 2018-05-04 | 国网上海市电力公司 | A kind of seamless combination method of ship shore electric |
| CN109039097B (en) * | 2018-09-14 | 2020-12-25 | 西门子电气传动有限公司 | Variable frequency control method and device, shore power system and storage medium |
| CN109560717A (en) * | 2018-12-12 | 2019-04-02 | 苏州汇川技术有限公司 | Control method, main control unit, storage medium and the system of variable-frequency power sources parallel system |
| CN111585302B (en) * | 2020-04-27 | 2021-09-14 | 武汉天富海科技发展有限公司 | Ship inverter grid-connected optimization method based on improved droop control |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6150731A (en) * | 1999-02-16 | 2000-11-21 | Electric Boat Corporation | Integrated high frequency marine power distribution arrangement with transformerless high voltage variable speed drive |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN201130909Y (en) * | 2007-11-13 | 2008-10-08 | 青岛经济技术开发区创统科技发展有限公司 | Removable shore power supply |
| CN101488720A (en) * | 2008-10-24 | 2009-07-22 | 青岛经济技术开发区创统科技发展有限公司 | Large power ship shore electric power |
| CN102255517A (en) * | 2011-06-11 | 2011-11-23 | 台州富凌电气有限公司 | Shore power supply for ship |
| CN202455277U (en) * | 2012-01-30 | 2012-09-26 | 荣信电力电子股份有限公司 | Shore power supply for medium-low voltage ship |
| CN103532138A (en) * | 2013-10-21 | 2014-01-22 | 安徽天沃电气技术有限公司 | Intelligent high-voltage shore power supply system for boat on dock |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6150731A (en) * | 1999-02-16 | 2000-11-21 | Electric Boat Corporation | Integrated high frequency marine power distribution arrangement with transformerless high voltage variable speed drive |
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