CN107732900B

CN107732900B - Ship shore power connection method and system

Info

Publication number: CN107732900B
Application number: CN201710890705.9A
Authority: CN
Inventors: 肖乐明; 韩佳
Original assignee: Guangzhou Maritime University
Current assignee: Guangzhou Maritime University
Priority date: 2017-09-27
Filing date: 2017-09-27
Publication date: 2023-07-18
Anticipated expiration: 2037-09-27
Also published as: CN107732900A

Abstract

A method for receiving shore power from a ship comprises the following steps: inquiring whether the ship information requiring to connect shore power is input, if yes, executing the following steps: judging whether the ship is provided with a ship transformer for high-voltage boarding according to the ship transformer information, if so, selecting to connect high-voltage shore power, and if not, selecting to connect low-voltage shore power; if the low-voltage shore power is selected to be connected, judging whether the ship power distribution standard is consistent with the shore power system standard according to the ship power distribution information, if so, selecting the same-voltage same-frequency power supply, and if not, selecting the variable-voltage variable-frequency power supply; and judging whether the ship has a seamless shore power interface according to the seamless shore power interface information of the ship, if so, selecting the seamless shore power, and if not, selecting the power-off shore power. According to the invention, according to whether the ship is provided with the on-board transformer, the seamless shore power connection interface and the ship information of the ship power distribution standard, the mode of the ship to be connected with the shore power can be accurately judged, and the efficiency of the ship to be connected with the shore power is greatly improved.

Description

Ship shore power connection method and system

Technical Field

The invention relates to the technical field of ship electricity utilization, in particular to a method and a system for connecting shore power to a ship.

Background

Marine shore power technology refers to the access of a ship to a dockside power grid during a harbor, obtaining the power required for its water pumps, communications, ventilation, lighting and other facilities from an onshore power source, thereby shutting down its own diesel generator. The emission of waste gas can be effectively reduced after the ship is connected with the shore power, the energy-saving and environment-friendly system has the remarkable advantages of energy conservation and environment friendliness, and noise pollution generated by the operation of the generator set can be reduced, and the cost is reduced, so that the government and traffic departments, shipping enterprises and port enterprises can greatly push the use of the shore power.

However, most of the onshore power supplies are 400V/50Hz, and the existing ship power systems have various standards, such as 460V/60Hz power system, 400V/50Hz power system, or a fixed transformer is installed on the ship, so that the onshore 6.6kV high voltage power can be connected to the ship, and the fixed transformer on the ship is used for converting the onshore high voltage power into 460V high voltage power for supplying power, which is commonly called as high voltage on-board, and the ship is required to be provided with the transformer. In addition, the interfaces of the ship power are different, some ships are provided with seamless shore power interfaces, so that the seamless switching can be performed between the ship power and the shore power, namely, under the condition of continuously supplying the ship power, the power is directly supplied by a ship generator and is switched to the shore power supply, and other ships are not provided with the seamless shore power interfaces, so that the ship power is required to be stopped first and then connected. The different conditions of the ship often lead to selecting among a plurality of different power supply modes when the ship is connected with the shore power, the operation is chaotic, unified allocation is not possible, and the efficiency of the ship for connecting the shore power is greatly reduced.

Disclosure of Invention

Based on the above, the invention aims to provide a ship shore power connection method and a system with high efficiency.

The technical scheme adopted by the invention is as follows:

a method for receiving shore power from a ship comprises the following steps:

inquiring whether ship information input requesting to connect with shore power exists, wherein the ship information comprises ship seamless connection shore power interface information, ship transformer information, ship power distribution information and ship host information, if not, continuously inquiring whether the ship information input exists, and if so, executing the following steps:

judging whether the ship is provided with a ship transformer for carrying out 6.6kV high-voltage boarding according to the ship transformer information, if so, selecting to connect 6.6kV high-voltage shore power, and if not, selecting to connect 400V or 460V low-voltage shore power;

if the low-voltage shore power of 400V or 460V is selected to be connected, judging whether the ship power distribution standard is consistent with the shore power system standard according to the ship power distribution information, if so, selecting the same-voltage same-frequency power supply, and if not, selecting the variable-voltage variable-frequency power supply;

judging whether the ship has a seamless shore power interface or not according to the seamless shore power interface information of the ship, if so, selecting the seamless shore power, and if not, selecting the power-off shore power;

if the same-voltage same-frequency power supply and the seamless shore power connection are selected at the same time, judging whether the ship belongs to a large ship with the rated power of 3000 kilowatts or more of a host according to the information of the host of the ship, if so, selecting a state to follow a smooth switching method to connect the shore power, and if not, selecting a method based on a voltage difference envelope curve to connect the shore power;

If the variable-voltage variable-frequency power supply and the seamless shore power connection are selected at the same time, the shore power is connected by the smooth switching method in the selected state. The ship shore power connection method can accurately judge the mode of the ship for connecting the shore power according to whether the ship is provided with the transformer on the ship, whether the ship is provided with the seamless shore power connection interface and the ship information of the ship power distribution standard, and greatly improves the efficiency of ship shore power connection.

The state following smooth switching method and the voltage difference envelope curve-based method can realize seamless switching between ship electricity and shore electricity, power-off and restarting of ship equipment are not needed, power supply operation is simplified, and power supply safety is improved.

Further, if the shore power connection based on the voltage difference envelope curve method is selected, after the ship is landed, the following steps are executed:

measuring the voltage frequency of the ship through an accurate frequency meter arranged on the ship power distribution device, and manually or automatically adjusting an engine throttle to adjust the voltage frequency of the ship, so that the voltage frequency of the ship is lower than the shore power frequency by 0.1-0.5 Hz;

after the voltage difference envelope signals of the ship electricity and the shore electricity are obtained, converting the voltage difference envelope signals into periodic forward pulsation signals;

Taking the lowest point of the periodic forward pulse signal as a datum point, taking T time before and after the datum point, and setting 2T time as a butting time period, wherein T is more than or equal to 0 and less than or equal to 0.01s;

and judging whether the current moment is in the docking time period, and docking the ship electricity with the shore power if the current moment is in the docking time period.

Compared with the prior art, the method and the device have the advantages that the voltage difference envelope signals of the shore power and the shore power are measured, the lowest point of the voltage difference envelope signals is obtained, the docking time period is set according to the lowest point, the closing signal is sent in the docking time period, the shore power and the shore power are seamlessly docked under the condition that the shore power is not disconnected, damage to the shore power transformation equipment, the ship generator and the ship equipment caused by circulation when the shore power and the shore power are connected is effectively prevented, and normal operation of the shore power, the ship generator and the ship equipment is ensured.

Further, if the selected state is followed by the smooth switching method to connect shore power, after the ship is on shore, the following steps are executed:

the shore power transformer and the rectifying inverter are respectively and electrically connected with a shore power supply and a ship power supply, and a 50Hz or 60Hz line is selected according to ship power distribution information;

an inner ring control method and an outer ring control method are adopted for the rectifying inverter, wherein the outer ring control method adopts a V/f control method, and the target frequency of the ship generator is converted into the target frequency output by the shore power transformer; meanwhile, a phase-locked loop control method is used for controlling the frequency and the voltage output by the rectifying inverter;

The outer ring control method of the rectifier inverter is converted into a P/Q control method from a V/f control method, the frequency and the voltage of the ship generator are controlled, the ship electricity real-time load power is taken as target power, and power transfer is carried out, so that the output power of the rectifier inverter is increased, and the output power of the ship generator is reduced; meanwhile, a phase-locked loop control method is used for controlling the frequency and the voltage output by the rectifying inverter;

and when the output power of the ship generator is reduced to the preset power, the ship generator is turned off.

According to the state following smooth switching method, when the power supply of the shore power and the ship power is switched, the equipment on the ship does not need to be powered off, the following frequency f is controlled through V/f, and then the load power is transferred from the ship generator to the shore power through P/Q control, so that seamless switching is completed; in addition, the shore power 50Hz power supply can be realized, the power supply is carried out on ships with 60Hz or 50Hz different power grid standards, the requirements of different ships are met, when the shore power is seamlessly connected to the 50Hz ships, the traditional synchronous meter or current limiting control is not needed, the 60Hz rectifier inverter is adopted as a 50Hz seamless smooth shore power connection transition device, after the switching is completed, the rectifier inverter is turned off, the 50Hz inverter power supply is converted to the shore power transformer direct power supply, and the smooth connection without impact current is realized.

A ship shore power connection system comprises a shore communication module and a judging module;

the shore communication module is used for inquiring whether the ship information requiring shore power connection is input, if yes, the ship information is transmitted to the judging module, and if not, whether the ship information is input is continuously inquired; the ship information comprises ship seamless shore power interface information, ship transformer information, ship power distribution information and ship host information;

the judging module is used for:

if the power supply is judged to be connected with 400V or 460V low-voltage shore power, judging whether the ship power distribution standard is consistent with the shore power system standard according to the ship power distribution information, if so, selecting the same-voltage same-frequency power supply, and if not, selecting the variable-voltage variable-frequency power supply;

when the same-voltage same-frequency power supply and the seamless shore power connection are selected at the same time, judging whether the ship belongs to a large ship with the rated power of 3000 kilowatts or more of a host according to the information of the host of the ship, if so, selecting a state to follow a smooth switching method to connect the shore power, and if not, selecting a method based on a voltage difference envelope curve to connect the shore power; when the variable-voltage variable-frequency power supply and the seamless shore power connection are selected at the same time, the shore power is connected by the smooth switching method in the selected state.

The ship shore power connection system can accurately judge the mode of the ship for connecting the shore power according to whether the ship is provided with the transformer on the ship, whether the ship is provided with the seamless shore power connection interface and the ship information of the ship power distribution standard, and greatly improves the efficiency of ship shore power connection.

Further, the system also comprises a central processing module and a first power supply module; the central processing module receives the selection result of the judging module, and if the shore power is connected based on the voltage difference envelope curve method, the central processing module informs the first power supply module;

the first power supply module comprises a shore power transformer, a first switch, a voltage difference envelope detection device, a control component and a second switch;

the shore power transformer is connected to ship power through the first switch; the voltage difference envelope detection device is connected with the first switch in parallel, converts the acquired voltage difference envelope signal between shore power and ship power into a periodic forward pulse signal, and transmits the periodic forward pulse signal to the control assembly; the control component is respectively connected with the voltage difference envelope detection device and the first switch; the control component takes the lowest point of the periodic forward pulse signal as a datum point, takes T time before and after the datum point, sets 2T time as a butt-joint time period, and sends a closing signal to the first switch in the butt-joint time period to control the first switch to be closed; wherein T is more than or equal to 0 and less than or equal to 0.01s;

The second switch is used for controlling whether the voltage difference envelope detection device is connected or not; the first switch is provided with a first set of contact points for electrically connecting with the ship and a second set of contact points for connecting with a shore power transformer; a first set of input terminals of the voltage difference envelope detection device are connected with the first set of contact points; the second set of input terminals of the voltage difference envelope detection apparatus are connected to the second set of contact points through the second switch.

Compared with the prior art, the method and the device have the advantages that the voltage difference envelope signals of the shore power and the shore power are measured, the lowest point of the voltage difference envelope signals is obtained, the docking time period is set according to the lowest point, the closing signal is sent in the docking time period, the shore power and the shore power are seamlessly docked under the condition that the shore power is not disconnected, damage to the shore power voltage transformation equipment, the ship generator and the ship equipment caused by circulating current when the shore power and the shore power are connected is effectively prevented, and normal operation of the shore power, the ship generator and the ship equipment is ensured. When the voltage difference envelope signals of the ship electricity and the shore electricity are required to be detected, the second switch (K3) is switched on, the voltage difference envelope detection device is connected to the ship electricity and the shore electricity for detection, when the voltage difference envelope signals of the ship electricity and the shore electricity are not required to be detected, the second switch (K3) is switched on, the voltage difference envelope detection device is disconnected from the ship electricity and the shore electricity, and damage to the voltage difference envelope detection device caused by unstable voltage of the ship electricity and the shore electricity can be prevented.

Further, the first power supply module further comprises a first phase sequence switch and a second phase sequence switch which are connected in parallel; the A phase, the B phase and the C phase of the ship electricity are respectively connected with the U phase, the V phase and the W phase of the output end of the shore power transformer through a first phase sequence switch and a first switch; the control assembly further comprises a phase sequence detection device; one end of the phase sequence detection device is connected with the A phase, the B phase and the C phase of the ship electricity respectively, and the other end of the phase sequence detection device is connected with the U phase, the V phase and the W phase of the output end of the shore power transformer respectively so as to detect whether the phase sequences of the ship electricity and the shore power are consistent or not: if the phase sequences are consistent, closing the first phase sequence switch; if the phase sequences are inconsistent, closing a second phase sequence switch;

the voltage difference envelope detection device comprises a voltage difference acquisition circuit, an absolute value conversion circuit and a shaping detection circuit; the two input ends of the voltage difference acquisition circuit are respectively connected in parallel with the two ends of the first switch, and voltage difference envelope signals of ship electricity and shore electricity are acquired; the output end of the voltage difference acquisition circuit is connected with the input end of the absolute value conversion circuit, and the voltage difference envelope signal is transmitted to the absolute value conversion circuit; the output end of the absolute value conversion circuit is connected with the input end of the shaping detection circuit, and the voltage difference envelope signal is converted into a forward voltage difference envelope signal and then transmitted to the shaping detection circuit; the shaping detection circuit carries out detection processing on the voltage difference envelope signal, converts the voltage difference envelope signal into a periodic forward pulsation signal and then transmits the periodic forward pulsation signal to the control component;

The control assembly comprises a singlechip and an industrial control computer; the input end of the singlechip is connected with the output end of the voltage difference envelope detection device, samples and filters the periodic forward pulse signal, sets a docking time period by taking the lowest point of the periodic forward pulse signal as a datum point, and sends a docking signal to the industrial control computer in the docking time period; the industrial control computer sends a closing control signal to the first switch according to the butt joint signal, and the first switch receives the closing control signal and closes;

the voltage difference acquisition circuit comprises a group of Hall voltage sensor assemblies; the Hall voltage sensor assembly comprises a first voltage dividing resistor, a second voltage dividing resistor, a first Hall voltage sensor and a first measuring resistor; the first input end of the first Hall voltage sensor is connected with a first contact point of the first switch through the first voltage dividing resistor; the second input end of the first Hall voltage sensor is connected with a second contact point of the second switch through the second voltage dividing resistor, and the first Hall voltage sensor respectively acquires a phase voltage of ship electricity and a phase voltage of shore power corresponding to the phase voltage of the ship electricity through the first input end and the second input end, so as to acquire voltage difference envelope signals of the ship electricity and the shore power of one phase; the output end of the first Hall voltage sensor is connected with the input end of the absolute value conversion circuit and is grounded through the first measuring resistor;

The first power supply module further comprises an accurate frequency meter arranged on the ship power distribution device, the accurate frequency meter is used for measuring ship electricity frequency, and according to the ship electricity frequency measured by the accurate frequency meter, an engine throttle is manually or automatically adjusted to adjust the ship electricity frequency, so that the ship electricity frequency is lower than the shore electricity frequency by 0.1Hz-0.5Hz, and then the ship electricity and the shore electricity are in butt joint.

The voltage difference envelope detection device can be quickly connected with ship electricity and shore electricity with consistent phase sequences through simple switching of the first phase sequence switch (K1) and the second phase sequence switch (K4); the method comprises the steps of obtaining voltage difference envelope signals of ship electricity and shore electricity, and converting and shaping the voltage difference envelope signals to obtain stable periodic signals; receiving a stable ground voltage difference envelope signal transmitted by a voltage difference envelope detection device through a singlechip to quickly and accurately acquire a docking time period; then, an opening signal is sent to the first switch (K2) through the industrial control computer so as to improve the response speed of the whole system; according to the invention, the first Hall voltage sensor generates an electromagnetic field under the action of lorentz force through two different voltage signals of ship electricity and shore power input by two input ends, so that a voltage difference envelope signal of the ship electricity and the shore power is rapidly obtained; by setting the accurate frequency table, the highest load power born by the generator reaches 100%, the lowest load power reaches-30%, and the ideal state is about 50%. The situation that the power of the shore power is too high and the generator shakes is prevented, so that the generator is tripped; the power of the generator is too high, so that the generator can automatically trip, load impact can be caused to shore power in the process, and the shore power passing gate trip can occur in severe cases.

Further, the system also comprises a central processing module and a first power supply module; the central processing module receives the selection result of the judging module, and if the selection state is connected with shore power by following the smooth switching method, the central processing module informs the second power supply module;

the second power supply module comprises a shore power transformer, a rectifying inverter, a 50Hz line, a 60Hz line, a public line, an inner loop controller and an outer loop controller, wherein the outer loop controller comprises a V/f controller, a P/Q controller and a phase-locked loop controller;

the shore power transformer, the rectifying inverter, the 50Hz line and the public line are sequentially connected, the shore power transformer, the rectifying inverter, the 60Hz line and the public line are sequentially connected, and the 50Hz line or the 60Hz line is selected according to the ship power distribution information; the other end of the shore power transformer is used for being connected with a shore power supply, and the other end of the public line is used for being electrically connected with a ship;

the V/f controller is used for converting the target frequency of the ship generator into the target frequency output by the shore power transformer;

the P/Q controller is used for controlling the frequency and the voltage of the ship generator after the V/f controller finishes processing, taking the ship electric real-time load power as target power, performing power transfer, increasing the output power of the rectifying inverter, reducing the output power of the ship generator, and closing the ship generator when the output power of the ship generator is reduced to or below the preset power;

The phase-locked loop controller is used for controlling the frequency and the voltage output by the rectifying inverter.

According to the invention, the second power supply module adopts a state following smooth switching method, so that when the power supply of the shore power and the power supply of the ship power are switched, the equipment on the ship does not need to be powered off, the following frequency f is controlled through V/f, and then the load power is transferred from the ship generator to the shore power through P/Q control, so that the seamless switching is completed; in addition, the shore power 50Hz power supply can be realized, the power supply is carried out on ships with 60Hz or 50Hz different power grid standards, the requirements of different ships are met, when the shore power is seamlessly connected to the 50Hz ships, the traditional synchronous meter or current limiting control is not needed, the 60Hz rectifier inverter is adopted as a 50Hz seamless smooth shore power connection transition device, after the switching is completed, the rectifier inverter is turned off, the 50Hz inverter power supply is converted to the shore power transformer direct power supply, and the smooth connection without impact current is realized.

Further, the 50Hz line comprises a sixth switch, a seventh switch, a first inductor, a second inductor, a fourth inductor and a first capacitor; the 60Hz line comprises an eighth switch, a third inductor, a fifth inductor and a second capacitor; the public line comprises a fourth resistor, a sixth inductor and a ninth switch;

One end of the shore power transformer is used for being connected with a shore power supply, the other end of the shore power transformer is connected with one end of the rectifying inverter and the sixth switch, and the other end of the rectifying inverter is respectively connected with one ends of the seventh switch and the eighth switch; the other end of the sixth switch is connected with the other end of the seventh switch after being connected with the first inductor in series, the other end of the seventh switch is connected with the first connecting end of the second inductor, the second connecting end of the second inductor is sequentially connected with one ends of the fourth inductor, the fourth resistor, the sixth inductor and the ninth switch in series, one end of the first capacitor is connected between the second inductor and the fourth inductor, and the other end of the first capacitor is grounded; the other end of the eighth switch is connected with the first connecting end of the third inductor, the second connecting end of the third inductor is sequentially connected with one ends of the fifth inductor, the fourth resistor, the sixth inductor and the ninth switch in series, one end of the second capacitor is connected between the third inductor and the fifth inductor, and the other end of the second capacitor is grounded; the other end of the ninth switch is used for being electrically connected with the ship;

and the preset power is 5% of rated power of the ship generator.

For a better understanding and implementation, the present invention is described in detail below with reference to the drawings.

Drawings

FIG. 1 is a schematic view of a marine shore power system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a voltage difference envelope-based method according to a first embodiment of the present invention;

FIG. 3 is a schematic signal diagram of a voltage difference envelope method according to a first embodiment of the present invention;

FIG. 4 is a schematic diagram of voltage difference envelope signals of ship electricity and shore power according to a first embodiment of the present invention;

FIG. 5 is a circuit diagram of a Hall voltage sensor assembly according to a first embodiment of the present invention;

FIG. 6 is a graph of three sets of output waveforms measured when the Hall voltage sensor of the first embodiment of the present invention is idle;

FIG. 7 is a waveform diagram showing the output of a Hall voltage sensor connected to ship electricity and shore power according to the first embodiment of the present invention;

fig. 8 is a circuit diagram of an absolute value conversion circuit according to a first embodiment of the present invention;

fig. 9 is a waveform diagram of an output of the absolute value conversion circuit according to the first embodiment of the present invention;

fig. 10 is a circuit diagram of a shaping detection circuit according to the first embodiment of the present invention;

FIG. 11 is a diagram showing the comparison of the output waveform and the voltage difference envelope curve of the shaping detection circuit according to the first embodiment of the present invention;

FIG. 12 is a waveform diagram of a single chip microcomputer output according to a first embodiment of the present invention;

fig. 13 is a schematic diagram of a state-following smooth switching method according to the first embodiment of the present invention;

fig. 14 is a circuit diagram of a voltage difference envelope detection apparatus according to a second embodiment of the invention.

Detailed Description

Example 1

Fig. 1 is a schematic diagram of a shore power connection system of a ship according to a first embodiment of the present invention. The ship shore power connection system comprises a shore communication module, a judging module, a central processing module, a first power supply module, a second power supply module, a third power supply module, a fourth power supply module, a detecting module and a charging module. The detection module comprises a frequency detection module, a voltage detection module, a current detection module and a phase detection module. In this embodiment, the shore power supply can provide the following two power supply standards, 400V/50Hz and 6.6kV/60Hz.

The invention relates to a shore power connection method for a ship, which comprises the following steps of:

step 1: the shore communication module inquires whether the ship information requiring the shore power connection is input, wherein the ship information comprises ship seamless shore power interface information, ship transformer information, ship power distribution information, ship host information, ship related information such as ship name, ship model, ship type, shore time and the like, if not, whether the ship information is input is continuously inquired, and if so, the step 12 is executed.

The ship information is transmitted to the shore communication module by the ship, and can be transmitted in a wired or wireless mode, the wired mode needs to be electrically connected with the shore communication module after the ship is on shore, and the wireless mode can be used for wireless information transmission before or after the ship is on shore, and the wireless mode is preferred in the embodiment. Specifically, a ship is provided with a ship wireless communication module, and the ship wireless communication module sequentially transmits ship information to the shore communication module through a maritime satellite and a ground base station.

The ship seamless shore power interface information refers to information whether a ship has a ship seamless shore power interface or not; the on-board transformer information refers to information whether the on-board transformer is provided or not, and can also further comprise related information of the transformer; the ship power distribution information is information such as power distribution voltage and power distribution frequency required for the ship, for example, 460V/60Hz, 400V/50Hz, 6.6kV/60Hz, or the like, and in this embodiment, three ship power distribution standards are described as an example. The ship host information refers to rated power information of a ship host, and the ship host refers to a diesel generator with the largest rated power on a ship.

Step 12: the judging module selects corresponding berths suitable for the size and the type of the ship according to the ship model and the ship type information.

Step 2: the judging module judges whether the ship is provided with a ship transformer for carrying out high-voltage boarding according to the ship transformer information, if so, the high-voltage shore power is selected to be connected, and if not, the low-voltage shore power is selected to be connected.

In particular, if the ship is equipped with a transformer, the high-voltage shore power is selected to be connected, i.e. the power is supplied by adopting a high-voltage boarding mode, for example, a ship with a power distribution standard of 6.6kV/60 Hz. If the ship is not equipped with a transformer, a low voltage shore power supply is selected, for example, a ship with a power distribution standard of 460V/60Hz or 400V/50 Hz.

Step 3: if the power is selected to be connected with the low-voltage shore power, the judging module judges whether the ship power distribution standard is consistent with the shore power system standard according to the ship power distribution information, if so, the same-voltage same-frequency power supply is selected, and if not, the variable-voltage variable-frequency power supply is selected; if the high-voltage shore power is judged to be connected, the step is not performed.

In the embodiment, the step adopts a shore power supply of 400V/50Hz, if the ship power distribution standard is 400V/50Hz, the same-voltage and same-frequency power supply is adopted, and if the ship power distribution standard is 460V/60Hz, the variable-voltage and variable-frequency power supply is adopted.

Step 4: the judging module judges whether the ship has a seamless shore power interface according to the seamless shore power interface information of the ship, if so, the seamless shore power is selected, and if not, the power-off shore power is selected.

Step 5: if the same-voltage same-frequency power supply and the seamless shore power connection are selected at the same time, the judging module judges whether the ship belongs to a large ship with the rated power of 3000 kilowatts or more according to the information of the ship host, if so, the state is selected to follow the smooth switching method to connect the shore power, and if not, the shore power is selected to be connected based on the voltage difference envelope curve method; if the variable-voltage variable-frequency power supply and the seamless shore power connection are selected at the same time, the shore power is connected by the smooth switching method in the selected state. If the high-voltage shore power connection or the power failure shore power connection is judged, the step is not carried out.

Step 6: the judgment module sends the selection result to the central processing module and the shore communication module, and the shore communication module sends the selection result to the ship wireless communication module. The central processing module displays ship information and corresponding selection results through the display and informs on-shore workers of preparing to connect with shore power.

For example, if the power distribution standard is 400V/50Hz and the small-sized ship has a seamless shore power interface (the rated power of a main engine of the small-sized ship is less than 3000 kw), the information of "low-voltage shore power connection-same-voltage same-frequency power supply-seamless shore power connection-shore power connection based on a voltage difference envelope method" is transmitted. And if the power distribution standard is 400V/50Hz and the large ship is provided with a seamless shore power interface, sending the information of 'connecting low-voltage shore power-same-voltage and same-frequency power supply-seamless shore power-state following smooth switching method to connect shore power'. And if the power distribution standard is 460V/60Hz and the ship is provided with a seamless shore power interface, sending the information of 'connecting low-voltage shore power-variable-voltage variable-frequency power supply-seamless shore power-state following smooth switching method to connect shore power'. And if the power distribution standard is 6.6kV/60Hz and the ship is provided with a seamless shore power interface, sending the information of 'connecting high-voltage shore power-seamless shore power'. And if the power distribution standard is 460V/60Hz and the ship does not have a seamless shore power connection interface, sending the information of 'connecting low-voltage shore power-transforming variable-frequency power supply-disconnecting electricity-connecting shore power'.

Step 7: the ship is berthed at the corresponding berth of the wharf according to the selection result. On the wharf, different berths are correspondingly used for berthing ships with different sizes and types, the shore connection equipment of each berth is also different, and according to the selection result, the judging module selects the berths corresponding to the sizes, the types and the shore connection modes for the ships. For example, a small ship with a power distribution standard of 400V/50Hz and a seamless shore power interface, selecting a berth matched with the size of the ship and provided with related equipment for shore power connection based on a voltage difference envelope method; if the power distribution standard is 6.6kV/60Hz, and the ship is provided with a seamless shore power interface, selecting a berth matched with the size of the ship and provided with related equipment on the high-voltage ship; if the ship does not have a seamless shore power interface, a berth matched with the size of the ship and provided with power-off shore power equipment is selected for the ship.

And the central processing module receives the selection result of the judging module and informs the corresponding module to operate by using a corresponding shore power connection method. If the shore power connection based on the voltage difference envelope method is selected, the first power supply module is notified, and step 71 is performed. If the selected state follows the smooth switching method to connect to shore power, the second power module is notified and step 72 is performed. If a high voltage boarding is selected (i.e. high voltage shore power is connected), the third power module is notified and step 73 is performed. If power is selected to be off, the fourth power module is notified and step 74 is performed.

(1) Shore power connection method based on voltage difference envelope curve

The first power supply module is used for realizing a voltage difference envelope curve-based method, and comprises a shore power transformer T1, a first switch K2, a second switch K3, a voltage difference envelope curve detection device 11 and a control component 12.

Referring to fig. 2 and fig. 3, fig. 2 is a schematic diagram of a voltage difference envelope-based method according to a first embodiment of the invention; fig. 3 is a schematic signal diagram of a voltage difference envelope method according to a first embodiment of the invention.

The shore power transformer T1 and the first switch K2 are sequentially connected and connected into ship power. The first switch K2 is provided with a first set of contact points for electrical connection with the ship and a second set of contact points for connection with the shore power transformer T1. A first set of input terminals of said voltage difference envelope detection means 11 is connected to said first set of contact points; the second set of input terminals of the voltage difference envelope detection means 11 is connected via the second switch K3 to the second set of contact points for parallel connection with the first switch K2. The control unit 12 is connected to the voltage difference envelope detection device 11 and the first switch K2, respectively.

The voltage difference envelope detection device 11 acquires a voltage difference envelope signal between a shore power supply and ship power, converts the voltage difference envelope signal into a periodic forward pulse signal and then transmits the periodic forward pulse signal to the control component 12; the control component 12 takes the lowest point of the periodic forward pulse signal as a reference point, takes T time before and after the reference point, sets the 2T time as a docking time period, sends a closing signal to the first switch K2 in the docking time period, controls the first switch K2 to close, and accesses a shore power supply through a shore power transformer T1, thereby realizing seamless docking of shore power and ship power. Wherein T is more than or equal to 0 and less than or equal to 0.01s, the period of alternating current is 0.02s, and the closing time point is extracted in a half period.

Specifically, let u ₁ 、u ₂ Respectively expressed as ship electricity and shore electricity, and the voltage values of the two voltages can be expressed by sine functions, wherein U ₁ 、U ₂ Amplitude voltages of ship electricity and shore power voltage respectively; omega ₁ ＝2uf ₁ 、ω ₂ ＝2uf ₂ And omega ₁ And omega ₂ Angular frequency, f, expressed as ship and shore power, respectively ₁ And f ₂ Frequencies respectively denoted ship electricity and shore power;and->And respectively representing the phases of the ship electricity and the shore power voltage, wherein the voltage difference u between the ship electricity and the shore power meets the following formula:

u＝u ₁ -u ₂ ＝U ₁ sin(ω _l t+ψ ₁ )-U ₂ sin(ω ₂ t+ψ ₂ )

set U ₁ ＝U ₂ ＝U

It is known that the voltage difference between the ship electricity and the shore electricity is composed of a high-frequency sine part and a low-frequency cosine part.

Please refer to fig. 4, which is a schematic diagram of voltage difference envelope signals of the ship power and the shore power according to the first embodiment of the present invention, specifically, fig. (a) is an envelope diagram of the ship power and the shore power with the same voltage amplitude and different frequencies; the graph (b) is an envelope diagram when the voltage amplitudes and frequencies of the ship electricity and the shore electricity are different; fig. (c) is an envelope of phases of ship electricity and shore electricity; the graph (d) is an envelope graph when the voltage amplitudes of the ship electricity and the shore electricity are the same and the frequencies and phases are different, wherein the abscissa of the four graphs represents time and the ordinate represents the voltage difference amplitude.

Assuming that the standard of shore power and shore power is 400V/50Hz, and under the condition that fluctuation exists, the voltage difference amplitude delta U=10% U of the shore power and the shore power, and the shore power Frequency difference Δf=0.5 Hz, phase difference between ship electricity and shore electricity(wherein, ψ ₁ ＝π/2，Ψ ₂ = -pi/2), transient voltage difference envelope range: 0 to 1200V (i.e. equivalent to 0 to 1.5X2U) ₁ ) The envelope period is about 4s. The graph (a) shows that when the voltage amplitudes of the ship electricity and the shore power are the same and the frequencies are different, the envelope line has zero crossing points, namely the circulation between the ship electricity and the shore power is 0, and at the moment, the influence generated when the uninterruptible power is connected to the shore power is the smallest, so that the method can be used as the best time when the ship electricity and the shore power are in seamless butt joint.

In the invention, if the phase sequences of the ship electricity and the shore electricity are consistent, such as the phase sequences of the A phase, the B phase and the C phase of the shore electricity and the U phase, the V phase and the w phase of the ship electricity are consistent, according to the symmetry of the three-phase voltage, only the relative voltage of one phase, such as the voltage difference of the A phase and the U phase of the ship electricity of the shore electricity, is needed to be measured, and the optimal time for the seamless docking of the ship electricity and the shore electricity can be determined according to the relative voltage of the relative phase. Therefore, in this embodiment, when the phase sequences of the ship electricity and the shore electricity are consistent, the relative voltage of one phase is measured to describe how to select the best time when the ship electricity and the shore electricity are in seamless connection.

The voltage difference envelope detection apparatus 11 includes a voltage difference acquisition circuit 111, an absolute value conversion circuit 112, and a shaping detection circuit 113. The two input ends of the voltage difference acquisition circuit 111 are respectively connected in parallel to the two ends of the first switch K2, and acquire voltage difference envelope signals of any one-phase power supply of ship electricity and shore electricity; an output terminal of the voltage difference acquisition circuit 111 is connected to an input terminal of the absolute value conversion circuit 112, and transmits the voltage difference envelope signal to the absolute value conversion circuit 112; an output end of the absolute value conversion circuit 112 is connected with an input end of the shaping detection circuit 113, and converts the voltage difference envelope signal into a forward voltage difference envelope signal and then transmits the forward voltage difference envelope signal to the shaping detection circuit 113; the shaping detection circuit 113 performs detection processing on the voltage difference envelope signal, converts the voltage difference envelope signal into a periodic forward ripple signal, and transmits the periodic forward ripple signal to the control unit 12.

Referring to fig. 5 to 7, fig. 5 is a circuit diagram of a hall voltage sensor assembly according to a first embodiment of the invention; FIG. 6 is a graph of three sets of output waveforms measured when the Hall voltage sensor is empty in the first embodiment; fig. 7 is a waveform diagram of output of the hall voltage sensor connected to the ship power and the shore power in the first embodiment. Wherein the abscissa of fig. 6 represents time in ms; the ordinate represents the voltage difference amplitude, in V; the abscissa of fig. 7 represents time in ms; the ordinate indicates the voltage difference amplitude in mV.

The voltage difference acquisition circuit 111 includes a set of hall voltage sensor assemblies. The Hall voltage sensor assembly comprises a first wiring seat X1, a first voltage dividing resistor R1, a second voltage dividing resistor R2, a first Hall voltage sensor A1 and a first measuring resistor R3. The first phase voltage of the ship electricity is connected with the first wiring terminal of the first wiring seat X1 through the first group of contact points of the first switch K2; and a phase voltage of the shore power is connected with a second wiring terminal of the first wiring seat X1 through a second group of contact points of the first switch K2, wherein the phase voltage of the shore power and the phase voltage of the shore power are consistent in phase sequence. A first input end of the first hall voltage sensor A1 is connected with a first wiring terminal of the first wiring seat X1 through the first voltage dividing resistor R1; the second input end of the first hall voltage sensor A1 is connected with the second wiring terminal of the first wiring seat X1 through the second voltage dividing resistor R2, and the first hall voltage sensor A1 respectively obtains a phase voltage of the ship electricity and a shore power phase voltage corresponding to the phase voltage of the ship electricity through the first input end and the second input end, so as to obtain a voltage difference envelope signal of the ship electricity and the shore power of one phase; the output end of the first hall voltage sensor A1 is connected to the input end of the absolute value conversion circuit 112, and is grounded through the first measuring resistor R3.

Because the current ship electricity frequency meter may have errors, the accurate frequency meter is further arranged on the ship power distribution device before the ship electricity and the shore power are in butt joint, the ship electricity frequency is measured through the accurate frequency meter, and an engine throttle is manually or automatically adjusted to adjust the ship electricity frequency, so that the ship electricity frequency is 0.1Hz-0.5Hz lower than the shore electricity frequency, and then the ship electricity and the shore power are in butt joint, so that the highest load power borne by the generator is 100%, the lowest load power is 30%, and the ideal state is about 50%. The situation that the power of the shore power is too high and the generator shakes is prevented, so that the generator is tripped; the power of the generator is too high, so that the generator can automatically trip, load impact can be caused to shore power in the process, and the shore power passing gate trip can occur in severe cases.

The principle of the hall voltage sensor is specifically described below:

the connected ship electricity and shore power apply voltage to the primary side of the Hall voltage sensor, so that current is generated on the primary side, and a magnetic field is generated at the Hall element end in the Hall voltage sensor due to the action of Lorentz force, so that potential difference is generated at the Hall element end. When the voltage of the primary side end changes, the magnetic field of the Hall element end also changes correspondingly, and when the voltage is reversed, the magnetic field is reversed, and the Hall element end generates opposite potential difference. The current signal is amplified through an operational amplifier in the Hall voltage sensor and is output to an external first measuring resistor, and the voltage on the first measuring resistor is equal-proportion voltage value of the primary side end.

Referring to fig. 8 and fig. 9, fig. 8 is a circuit diagram of an absolute value conversion circuit in a first embodiment; fig. 9 is a waveform diagram of an output of the absolute value conversion circuit in the first embodiment, wherein the abscissa of fig. 8 represents time in ms; the ordinate indicates the voltage difference amplitude in mV.

The absolute value conversion circuit 112 includes a first bipolar input transistor amplifier D6 and a second bipolar input transistor amplifier D7, a first switching diode V45, and a second switching diode V36. The 4 pins of the first bipolar input transistor amplifier D6 are connected with-5V 1 voltage, the 7 pins of the first bipolar input transistor amplifier D6 are connected with 5V1 voltage, the 3 pins of the first bipolar input transistor amplifier D6 are grounded, and the 2 pins of the first bipolar input transistor amplifier D6 are connected with the output end of the first Hall voltage sensor through a resistor R94. A resistor R95 and a resistor R97 are further connected between the 2 pin of the first bipolar input transistor amplifier D6 and the 2 pin of the second bipolar input transistor amplifier D7, a resistor R96 is further connected between the 2 pin of the first bipolar input transistor amplifier D6 and the 3 pin of the second bipolar input transistor amplifier D7, the 6 pin of the first bipolar input transistor amplifier D6 is connected between the 3 pin of the first bipolar input transistor amplifier D6 and the resistor R96 through a forward first switching diode V45, and the pin is connected between the resistor R95 and the resistor R97 through a reverse second switching diode V36 so as to select a voltage output range; the 4 pin of the second bipolar input transistor amplifier D7 is connected with-5V 1 voltage, the 7 pin of the second bipolar input transistor amplifier D7 is connected with +5V1 voltage, the 6 pin of the second bipolar input transistor amplifier D7 outputs absolute value voltage, and the absolute value voltage is connected to the 2 pin of the second bipolar input transistor amplifier D7 through a resistor R98 so as to be fed back to a circuit.

Referring to fig. 10 and fig. 11, fig. 10 is a circuit diagram of a shaping detection circuit in the first embodiment; FIG. 11 is a graph showing the comparison of the waveform of the output of the shaping detection circuit and the envelope curve of the voltage difference in the first embodiment, wherein the abscissa in FIG. 11 represents time in s; the ordinate indicates the voltage difference amplitude in mV, and the image of the upper half of fig. 11 indicates the output waveform of the shaping detection circuit 113, and the lower half indicates the voltage difference envelope waveform.

The shaping detection circuit 113 includes a dual operational amplifier D8. The 8 pins of the double operational amplifier D8 are connected with +5V1 voltage, the 4 pins are grounded, and the 2 pins are connected between the resistor R99 and the resistor R100; the 3 pin is connected with the resistor R101 and then is connected with the 6 pin of the absolute value conversion circuit 112; the 1 pin is connected with the resistor R100 and the resistor R99 and then grounded, and the 1 pin outputs a shaping voltage after passing through the resistor R10 and the charging capacitor C40 and the charging capacitor C41 which are connected in parallel.

Please refer to fig. 12, which is a waveform diagram of the output of the single chip microcomputer in the first embodiment, wherein the abscissa in the diagram represents time, and the unit is s; the ordinate represents the voltage difference amplitude, unit mV, and the graph is the waveform of the output of the shaping detection circuit 113, the waveform of the voltage difference envelope, and the waveform of the output of the single chip in order from top to bottom.

The control assembly 12 includes a single-chip microcomputer 121 and an industrial control computer 122. The input end of the singlechip 121 is connected with the output end of the shaping detection circuit 113, samples and filters the periodic forward pulse signal, sets a docking time period by taking the lowest point of the periodic forward pulse signal as a reference point, and sends a docking signal to the industrial control computer 122 in the docking time period. The industrial control computer 122 sends a closing control signal to the first switch K2 according to the docking signal, and the first switch K2 closes, so that seamless docking between shore power and ship power is realized.

In order to prevent the motor and the ship electric components from being burnt out due to inconsistent phase sequences of the shore power and the ship power when the shore power is accessed, the port ship access shore power system based on the voltage difference envelope line further comprises a first phase sequence switch (K1) and a second phase sequence switch (K4). The control assembly 12 further comprises a phase sequence detection device 123 connected to the industrial computer. The connection relationship between the first phase sequence switch (K1), the second phase sequence switch (K4) and the phase sequence detecting means 123 will be described in detail.

Because the A phase, the B phase and the C phase of the ship electricity are consistent with the A2 phase, the B2 phase and the C2 phase of the motor G2, whether the U phase, the V phase and the W phase of the output end of the transformer are consistent with the A phase, the B phase and the C phase of the ship electricity can be determined by only detecting whether the U phase, the V phase and the W phase of the output end of the transformer are consistent with the A2 phase, the B2 phase and the C2 phase of the motor G2. Specifically, the A phase, the B phase and the C phase of the ship electricity are respectively connected with the U phase, the V phase and the W phase of the output end of the transformer through a first phase sequence switch (K1) and a first switch (K2); the phase A, the phase B and the phase C of the ship electricity are respectively connected with the phase V, the phase U and the phase W of the shore electricity correspondingly through a second phase sequence switch (K4) and a first switch (K2). One end of the phase sequence detection device is respectively connected with the A phase, the B phase and the C phase of the ship electricity, and the other end of the phase sequence detection device is respectively connected with the U phase, the V phase and the W phase of the output end of the transformer so as to detect whether the phase sequences of the ship electricity and the shore power are consistent or not: if the phase sequences are consistent, closing the first phase sequence switch (K1) and closing the second switch K3, and starting to detect a voltage difference envelope curve; if the phase sequences are not consistent, a second phase sequence switch (K4) is closed, and then detection of the voltage difference envelope curve is started.

In the invention, the frequency fluctuation of the ship electric engine is 0.5Hz, and the shore power frequency is standard 50Hz, so the frequency difference is within 1 percent. In order to facilitate the detection of the system, the first switch K2 can be switched on only when the frequency difference between shore power and ship power is set to be within 1%.

For this purpose, in the present embodiment, the control assembly 12 further includes a phase sequence detecting device 123, a phase detecting device 124, a voltage detecting device 125, a frequency detecting device 126, a current detecting device 127, and a display unit 128, which are connected to the industrial computer. The phase detecting device 124, the voltage detecting device 125, the frequency detecting device 126, and the current detecting device 127 are respectively connected between the detecting switch assembly K and the first contact point of the first switch K2, so as to detect the phase sequence, the phase, the voltage, the frequency, the current, and other power information of the ship electricity, and display the power information through the display unit 128. And the frequency of the shore power are compared to ensure that the switching-on is carried out only when the frequency of the shore power and the shore power is within 1 percent. Further, the control component 12 is further configured to detect and display information such as voltage, current, power factor, and frequency before and after switching off and switching on both the ship power and the shore power.

The working principle of the whole system is specifically described below:

1. Marine power uninterruptible power supply for shore power integration

And (5) connecting the cable, and closing a switch K5 of the ship generator. Sampling the ship electricity phase sequence, the phase, the voltage and the frequency through the industrial control computer 122, comparing the ship electricity phase sequence, the phase, the voltage and the frequency with the shore power, judging whether the A, B, C phase of the ship electricity corresponds to the U, V, W phase sequence of the shore power, if the phase sequences are consistent, closing the first phase sequence switch K1, and if the phase sequences are inconsistent, closing the second phase sequence switch K4; and then judging that the frequency of the ship electricity is 0.1Hz-0.5Hz lower than the frequency of the shore electricity, if the frequency of the ship electricity is 0.1Hz-0.5Hz lower than the frequency of the shore electricity, acquiring a voltage difference envelope signal of the ship electricity and the shore electricity, otherwise, not performing the butt joint work of the ship electricity and the shore electricity.

When the voltage difference envelope signals of the ship power and the shore power are detected, the industrial computer 122 is used for controlling the second switch K3 to be switched on, and the first Hall voltage sensor is used for acquiring the voltage difference envelope signals of any one-phase power supply of the ship power and the shore power and transmitting the voltage difference envelope signals to the absolute value conversion circuit 112; the absolute value conversion circuit 112 processes the voltage difference envelope signal, outputs a forward voltage difference envelope signal within a set range, and transmits the forward voltage difference envelope signal to the shaping detection circuit 113; the shaping detection circuit 113 shapes the forward voltage difference envelope signal to obtain a periodic forward pulse signal, and then the periodic forward pulse signal is transmitted to the singlechip 121; after the single chip microcomputer 121 samples and filters the forward pulse signal, a docking time period is set by taking the lowest point of the periodic forward pulse signal as a reference point, so that a periodic square wave signal is formed, a docking signal is sent to the industrial control computer 122 in the docking time period, the industrial control computer 122 sends a closing signal to the first switch K2, so that the first switch K2 is controlled to close, seamless docking of ship electricity and shore electricity is realized, and further transfer of ship electricity to shore electricity is realized.

2. Union of shore power into ship power

The switch K5 of the ship generator is switched on and voltage is established, at the moment, voltage difference and impact circulation are formed between the ship generator and the shore power transformer T1, the speed regulation switch of the ship generator is regulated, the industrial control computer 122 controls the first switch K2 to switch on, and then the shore power transformer T1 of shore power is cut off for voltage supply, so that the shore power is integrated into the ship power without power interruption.

The step 71 of the present invention specifically comprises the following steps:

step 711: and acquiring a voltage difference envelope signal of the ship electricity and the shore electricity, and converting the voltage difference envelope signal into a periodic forward pulsation signal.

The two input ends of the voltage difference acquisition circuit are respectively connected in parallel with the two ends of the first switch, and voltage difference envelope signals of any one-phase power supply of ship power and shore power are acquired; the output end of the voltage difference acquisition circuit is connected with the input end of the absolute value conversion circuit, and the voltage difference envelope signal is transmitted to the absolute value conversion circuit; the output end of the absolute value conversion circuit is connected with the input end of the shaping detection circuit, and the voltage difference envelope signal is converted into a forward voltage difference envelope signal and then transmitted to the shaping detection circuit; the shaping detection circuit carries out detection processing on the voltage difference envelope signal, converts the voltage difference envelope signal into a periodic forward pulsation signal and then transmits the periodic forward pulsation signal to the control component.

The specific structure and principle of the absolute value conversion circuit and the shaping detection circuit are identical to those of embodiment 1, and are not described here again. The structure of the voltage difference acquisition circuit is the structure disclosed in embodiment 1, and is used for directly acquiring voltage difference envelope signals of one-phase ship electricity and shore power. Or the structure of the voltage difference acquisition circuit is the structure disclosed in embodiment 2, and is used for acquiring voltage difference envelope signals of the ship electricity and the shore electricity of one phase through the gating of the voltage multiplexer.

In one embodiment, before acquiring the voltage difference envelope signals of the ship electricity and the shore electricity, it is further determined whether the phase sequence connection of the ship electricity and the shore electricity is consistent, if so, the voltage difference envelope signals of the ship electricity and the shore electricity are acquired, otherwise, the phase sequence connection of the ship electricity and the shore electricity is consistent by switching the phase sequence switch. Specifically, the phase A, the phase B and the phase C of the ship electricity are correspondingly connected with the phase U, the phase V and the phase W of the shore power through a first phase sequence switch K1 and a first switch K2; the phase A, the phase B and the phase C of the ship electricity are respectively corresponding to the phase V, the phase U and the phase W of the shore power through a second phase sequence switch K4 and a first switch K2; and comparing whether the phase sequences of the ship electricity and the shore electricity are consistent or not so as to switch on the first phase sequence switch K2 or the second phase sequence switch K4.

In one embodiment, because the current ship electricity frequency table may have errors, before the ship electricity and the shore power are in butt joint, an accurate frequency table is further arranged on the ship power distribution device, the ship electricity frequency is measured through the accurate frequency table, and the ship electricity frequency is adjusted manually or automatically by adjusting an engine throttle, so that the ship electricity frequency is 0.1Hz-0.5Hz lower than the shore electricity frequency, and then the ship electricity and the shore power are in butt joint, so that the load power borne by the generator is ensured to be 100% at the highest, 30% at the lowest, and the ideal state is about 50%. The situation that the power of the shore power is too high and the generator shakes is prevented, so that the generator is tripped; the power of the generator is too high, so that the generator can automatically trip, load impact can be caused to shore power in the process, and the shore power passing gate trip can occur in severe cases.

Step 712: taking the lowest point of the periodic forward pulse signal as a datum point, taking T time before and after the datum point, and setting the 2T time as a butting time period, wherein T is more than or equal to 0 and less than or equal to 0.01s.

Step 713: judging whether the current moment is in the butt joint time period, if so, butting the ship electricity with the shore power.

The periodic forward pulse signal is sampled and filtered through the singlechip, a docking time period is set by taking the lowest point of the periodic forward pulse signal as a datum point, the docking time period is used for transmitting a docking signal to the industrial control computer, the industrial control computer transmits a closing control signal to the first switch according to the docking signal, and the first switch is closed, so that the seamless docking of shore power and ship power is realized.

When the port ship is required to be offshore, the shore power is required to be executed to be uninterruptedly connected with the ship power, the switch of the ship power generator can be switched on and voltage is established, at the moment, voltage difference and impact circulation are formed between the ship power generator and a shore power transformer, a speed regulation switch of the ship power generator is regulated, the shore power transformer transfers load, when the load power of the shore power transformer is reduced to 5% PN, the industrial computer controls the switch-on, and then the power supply of the shore power transformer of the shore power is cut off, so that the shore power is uninterruptedly connected with the ship power.

Compared with the prior art, the method and the device have the advantages that the voltage difference envelope signals of the shore power and the shore power are measured, the lowest point of the voltage difference envelope signals is obtained, the docking time period is set according to the lowest point, the closing signal is sent in the docking time period, the shore power and the shore power are seamlessly docked under the condition that the shore power is not disconnected, damage to the shore power voltage transformation equipment, the ship generator and the ship equipment caused by circulating current when the shore power and the shore power are connected is effectively prevented, and normal operation of the shore power, the ship generator and the ship equipment is ensured.

(2) State following smooth switching method for connecting shore power

The second power supply module is used for realizing a state following smooth switching method.

Fig. 13 is a schematic diagram of a state-following smooth handoff method according to a first embodiment of the present invention. The second power supply module comprises a shore power transformer, a rectifying inverter, a 50Hz line, a 60Hz line, a public line and a control line, wherein the control line comprises an inner loop controller and an outer loop controller, and the outer loop controller comprises a V/f controller, a P/Q controller and a phase-locked loop controller. The shore power transformer of the second power supply module and the shore power transformer of the first power supply module can adopt the same shore power transformer, and are respectively connected with different circuits when adopting different shore power connection methods, and can also be two special shore power transformers which are respectively used for corresponding circuits of different shore power connection methods, and other devices are similar. In the embodiment, the shore power is made of 400V/50Hz, and can be seamlessly connected with a 400V/50Hz ship and a 460V/60Hz ship. 50Hz-60Hz means that 50Hz shore power is in butt joint with 60Hz ship electricity, a 60Hz line is adopted, 400V/50Hz shore power is in butt joint with 460V/60Hz ship electricity, 50Hz-50Hz means that 50Hz shore power is in butt joint with 50Hz ship electricity, and a 50Hz line is adopted, and 400V/50Hz shore power is in butt joint with 400V/50Hz ship electricity.

The shore power transformer T1, the rectifying inverter UI1, the 50Hz line and the public line are sequentially connected, and the shore power transformer T1, the rectifying inverter UI1, the 60Hz line and the public line are sequentially connected, and the 50Hz line or the 60Hz line is selected according to ship power distribution information; the other end of the shore power transformer is used for being connected with shore power, and the other end of the public line is used for being electrically connected with a ship.

Specifically, the 50Hz line includes a sixth switch K6, a seventh switch K7, a first inductor L1, a second inductor L2, a fourth inductor L4, and a first capacitor C1, the 60Hz line includes an eighth switch K8, a third inductor L3, a fifth inductor L5, and a second capacitor C2, and the common line includes a fourth resistor R4, a sixth inductor L6, and a ninth switch K9; one end of the shore power transformer T1 is used for being connected with shore power, the other end of the shore power transformer T1 is respectively connected with one end of the rectifying inverter UI1 and one end of the sixth switch K6, and the other end of the rectifying inverter UI1 is respectively connected with one end of the seventh switch K7 and one end of the eighth switch K8; the other end of the sixth switch K6 is connected with the other end of the seventh switch K7 after being connected with the first inductor L1 in series, the other end of the seventh switch K7 is connected with the first connecting end of the second inductor L2, the second connecting end of the second inductor L2 is sequentially connected with one ends of the fourth inductor L4, the fourth resistor R4, the sixth inductor L6 and the ninth switch K9 in series, one end of the first capacitor C1 is connected between the second inductor L2 and the fourth inductor L4, and the other end of the first capacitor C1 is grounded; the other end of the eighth switch K8 is connected with the first connecting end of the third inductor L3, the second connecting end of the third inductor L3 is sequentially connected with one ends of the fifth inductor L5, the fourth resistor R4, the sixth inductor L6 and the ninth switch K9 in series, one end of the second capacitor C2 is connected between the third inductor L3 and the fifth inductor L5, and the other end of the second capacitor C2 is grounded; the other end of the ninth switch K9 is for electrical connection with the boat. The fourth resistor R4 and the sixth inductor L6 are used for current limiting, and may be omitted in other embodiments.

Step 72 of the present invention specifically comprises the steps of:

step 721: the second power supply module is electrically connected with a shore power source and a ship power respectively, in particular to a shore power transformer and the shore power, and the other end of the public line is electrically connected with the ship; selecting a 50Hz or 60Hz line according to ship power distribution information; if the ship electricity standard is 50Hz, selecting a 50Hz line, and closing the seventh switch and the ninth switch; if the ship electricity standard is 60Hz, a 60Hz line is selected, and the eighth switch and the ninth switch are closed.

Step 722: the rectifying inverter adopts an inner ring control method and an outer ring control method, in the step, the outer ring control method adopts a V/f control method, and the target frequency of the ship generator is converted into the target frequency output by the shore power transformer; meanwhile, the frequency and the voltage are stabilized by matching with a phase-locked loop control method.

According to the theoretical basis of the V/f control of the rectifier inverter, the V/f control consists of a current inner ring and a voltage outer ring, and the main coefficients are as follows: current loop scaling factor K _pi And integral coefficient K _ii Ratio coefficient K of voltage ring _pv And integral coefficient K _iv A load equivalent resistance R, an equivalent reactance X and a filter inductance L are arranged _s Rectifying inverter output current non-capacitance filtering I ₁ ≈I ₂ ≈I、I _d 、I _q Respectively the dq axis component.

Setting a reference value U of a voltage ring _ref Is of the dq-axis component U of (2) _dref And U _qref For input, rectifying the dq-axis component V of the inverter output voltage _d And V _q For output, the system equation is the following:

specifically, in the present invention, step 722 includes the steps of:

step 7221: setting a point A at the second connection end of the second inductor and the second connection end of the third inductor to obtain a rectifying inverter output current value i at the point A ₁ And calculates the dq-axis component i thereof _1d 、i _1q The method comprises the steps of carrying out a first treatment on the surface of the B point is arranged between the fourth inductor and the fourth resistor and between the fifth inductor and the fourth resistor, and the output voltage value v and the current value i of the rectifying inverter at the B point are obtained ₂ Wherein the voltage v includes its abc axis component v _a 、v _b 、v _c Then calculate the current value i ₂ Is of the dq-axis component i of (2) _2d 、i _2q And the dq-axis component v of the voltage _d 、v _q ；

Step 7222: input ω, u _ref 、v _d 、v _q Obtaining a current loop reference value i according to a V/f control method _dref 、i _qref The specific formula is as follows:

θ＝∫(2πf-ω)dt,U _dref ＝u _ref cosθ,U _qref ＝u _ref sinθ,

i _dref ＝K _pv (u _dref -v _d )+K _iv ∫(u _dref -v _d )dt,i _qref ＝K _pv (u _dref -v _d )+K _iv ∫(u _qref -v _q )dt

wherein u is _ref As the reference value of the voltage loop, omega is the output angular frequency of the rectifying inverter according to the voltage setting of the ship electricity, namely the voltage frequency of the ship electricity is 60Hz, theta is the output voltage phase angle of the rectifying inverter, K _pv Is the ratio coefficient of the voltage ring, K _iv Is the integral coefficient of the voltage loop;

step 7223:input i _1d 、i _1q 、i _2d 、i _2q 、i _dref 、i _qref 、v _d 、v _q Obtaining v according to an inner loop control method _sd 、v _sq The specific formula is as follows:

v _sd ＝v _d -ωL _s i _lq +K _pi (i _dref -i _2d )+K _ii ∫(i _dref -i _2d )dt

v _sq ＝v _q -ωL _s i _lq +K _pi (i _qref -i _2q )+K _ii ∫(i _qref -i _2q )dt；

wherein K is _pi Is the current loop ratio coefficient, K _ii Is the integral coefficient of the current loop, L _s Is a filter inductance;

step 7224: input v _sd 、v _sq And calculating the abc axis component, converting the abc axis component into PWM, and outputting the PWM to a rectifying inverter.

In one embodiment, phase-locked loop control is performed to stabilize frequency and voltage while step 2 is performed.

According to the phase-locked loop control theory, when the frequency of the input quantity changes, the output of the three-phase-locked loop is still the same frequency and phase output signal as the input, and under the conditions that the input has direct current offset, three-phase asymmetry, harmonic distortion and the like, the three-phase-locked loop has better anti-interference capability. Referring to the following formula, wherein theta is the output voltage phase angle of the rectifier inverter, theta _pll Omega for phase-locked loop output _ff 、θ _ff The target values are respectively:

v _q ＝Vsin(θ-θ _pll )

θ＝ω ₀ t+θ ₀

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i.e. step 722 of the present invention, the following step 726 is performed simultaneously:

step 7261: second connection to second inductorThe point A is arranged at the second connecting end of the connecting end and the third inductor, and the output current value i of the rectifying inverter at the point A is obtained ₁ And calculates the dq-axis component i thereof _1d 、i _1q The method comprises the steps of carrying out a first treatment on the surface of the B point is arranged between the fourth inductor and the fourth resistor and between the fifth inductor and the fourth resistor, and the output voltage value v and the current value i of the rectifying inverter at the B point are obtained ₂ Wherein the voltage v includes its abc axis component v _a 、v _b 、v _c Then calculate the current value i ₂ Is of the dq-axis component i of (2) _2d 、i _2q And the dq-axis component v of the voltage _d 、v _q ；

Step 7262: input v _a 、v _b 、v _c 、ω _ff Obtaining phase-locked loop output theta according to phase-locked loop control method _pll The specific formula is as follows:

ω _pll ＝ω _ff +K _p.pll v _q +K _i.pll ∫v _q dt

wherein K is _p.pll Is the phase-locked loop ratio coefficient, K _i.pll Is the integral coefficient of phase-locked loop, omega _ff For theoretical angular frequency omega _ff ＝2*π*60Hz；ω _pll Angular frequency of the output voltage of the rectifying inverter;

step 7263: inputting theta _pll And outputting the processed signals to a rectifying inverter.

The phase-locked loop control method of step 726 can stabilize the output frequency and voltage of the rectifier inverter.

Step 723: the outer ring control method of the rectifier inverter is converted from a V/f control method to a P/Q control method, the frequency and the voltage of the ship generator are controlled, the ship electricity real-time load power is taken as target power, power transfer is carried out, the output power of the rectifier inverter is gradually increased, and the output power of the ship generator is gradually reduced; meanwhile, the frequency and the voltage are stabilized by matching with a phase-locked loop control method. In the process, the ship generator can reduce the load by controlling sagging, automatically modulating frequency and load or manually adjusting the speed regulator.

According to the rectification inverter P/Q control theory, the P/Q control realizes the maximum utilization rate of the intermittent power supply in the micro-grid, and outputs active and reactive power as reference values P thereof respectively _ref And Q _ref . The control principle is as follows: the power set value is subtracted from the measured value, and a current reference signal i is obtained after the power set value is passed through a proportional-integral controller _dref 、i _qref Thereby controlling the output power of the rectifying inverter, and the proportionality coefficient K of P/Q control _pP And integral coefficient K _iP Reference is made to the following formula:

P _ref ＝K _P/f (f _ref -f)

Q _ref ＝K _Q/f (U _ref -U)

specifically, in the present invention, step 723 includes the steps of:

step 7231: setting a point A at the second connection end of the second inductor and the second connection end of the third inductor to obtain a rectifying inverter output current value i at the point A ₁ And calculates the dq-axis component i thereof _1d 、i _1q The method comprises the steps of carrying out a first treatment on the surface of the B point is arranged between the fourth inductor and the fourth resistor and between the fifth inductor and the fourth resistor, and the output voltage value v and the current value i of the rectifying inverter at the B point are obtained ₂ Wherein the voltage v includes its abc axis component v _a 、v _b 、v _c Then calculate the current value i ₂ Is of the dq-axis component i of (2) _2d 、i _2q And the dq-axis component v of the voltage _d 、v _q ；

Step 7232: input v _d 、v _q 、i _2d 、i _2q 、P _ref 、Q _ref Obtaining a current loop reference value i according to a P/Q control method _dref 、i _qref The specific formula is as follows:

P＝v _d i _2d +v _q i _2q ,Q＝v _q i _2d +v _d i _2q

i _dref ＝K _pP (P _ref -P)+K _iP ∫(P _ref -P)dt

i _qref ＝K _pQ (Q _ref -Q)+K _iQ ∫(Q _ref -Q)dt

wherein P is _ref For the active power reference value, Q _ref For reactive power reference value, K _pP For the scaling factor of the active control, K _pQ For the proportionality coefficient of reactive control, K _iP For the integral coefficient of active control, K _iQ An integral coefficient for reactive power control;

Step 7233: input i _1d 、i _1q 、i _2d 、i _2q 、i _dref 、i _qref 、v _d 、v _q Obtaining v according to an inner loop control method _sd 、v _sq The specific formula is as follows:

step 7234: input v _sd 、v _sq And calculating the abc axis component, converting the abc axis component into PWM, and outputting the PWM to a rectifying inverter.

While the step 3 is performed, the phase-locked loop control is performed to stabilize the frequency and the voltage, that is, the step 6 is performed simultaneously, and the step 6 is already described above, which is not repeated.

Step 724: and when the output power of the ship generator is reduced to the preset power, the ship generator is closed, and the seamless power supply switching is completed. Specifically, the rated power of the ship generator with the preset power of 5% can be set to be other sizes according to the situation.

Step 725: if the ship electricity standard is 50Hz, namely the ship electricity and the shore power are both 400V/50Hz, the rectification inverter is not needed to carry out transformation and frequency modulation, and the rectification inverter can be bypassed at the moment, and the shore power transformer is used for directly supplying power so as to save electric energy, in particular to close a sixth switch; if the ship electrical standard is 60Hz, this step is not performed, i.e., step 724 has completed the operation.

When the ship needs to be offshore, the reverse operation of the steps is adopted: firstly, starting a ship generator, connecting the generator with a second power supply module, transferring load power of the shore rectifying inverter to the ship generator, and matching the ship with accelerator and accelerator operation, wherein when the load power of the shore rectifying inverter is reduced to 5% rated power or below (the current is very small at the moment), the second power supply module is disconnected from ship electricity, so that seamless power supply switching is completed.

(3) High-pressure boarding

Step 73: and electrically connecting the shore power of 6.6kV/60Hz with the ship, controlling the load of the ship to transfer to the shore power by a third power supply module, and closing the ship generator after the transfer is completed. The step may specifically be a high-pressure boarding method in the prior art, which is not described herein.

(4) Power-off shore power connection

Step 74: and closing the equipment on the ship, closing the ship generator, connecting a corresponding shore power source with the ship according to ship power distribution information by a fourth power supply module, wherein the shore power source is connected with the shore power of 6.6kV/60Hz when the ship power is 6.6kV/60Hz, the shore power source is connected with the shore power source of 400V/50Hz when the ship power is 400V/50Hz, and the shore power source is connected with the ship after the shore power source is transformed and converted through a shore power transformer and a rectifying inverter when the ship power is 460V/60 Hz. After the shore power source is connected with the ship, equipment on the ship is started.

Step 8: the detection module detects frequency, voltage, current and phase information when the shore power supplies power to the ship and transmits the information to the charging module. The charging module calculates the current total electricity consumption and the current electricity consumption, and sends the current total electricity consumption and the current electricity consumption to the central processing module and the shore communication module, and the shore communication module sends the current total electricity consumption and the current electricity consumption to the ship wireless communication module. The method specifically comprises the following steps:

step 81: the frequency detection module, the voltage detection module, the current detection module and the phase detection module respectively detect frequency, voltage, current and phase information when the shore power supplies power to the ship.

Step 82: the charging module receives the information and according to the formulaCalculating in real time to obtain the output electric quantity of the shore power in the power supply process, wherein W is the current total power consumption, t is the current duration of the shore power for supplying power to the ship, U is the instant line voltage of the shore power supply, I is the instant line current of the shore power supply>For the phase difference of the present phase voltage and the present phase current, < >>Is the instantaneous power factor of the shore power supply. The charging module also calculates corresponding electricity charge according to the current total electricity consumption.

Step 83: the charging module sends the current total electricity charge and the current electricity charge to the central processing module and the shore communication module, and the shore communication module sends the current total electricity charge and the current electricity charge to the ship wireless communication module.

In addition, if the vessel type is a tanker or a liquefied gas tanker or other special vessel type with restrictions, shore power cannot be accessed without passing through the safe handling of shore power.

The ship shore power connection method and the system can accurately judge the mode of ship shore power connection according to whether the ship is provided with a ship transformer, a seamless shore power connection interface and the ship information of the ship power distribution standard, and greatly improve the efficiency of ship shore power connection; furthermore, various power supply modes are provided for ships with different power distribution standards, the provided state following smooth switching method and the voltage difference envelope curve-based method can realize seamless switching between ship power and shore power, equipment on the ship does not need power failure and restarting, power supply operation is simplified, and power supply safety is improved.

Example two

The ship shore power connection method and system of the present embodiment are basically the same as the first embodiment, the principle of the voltage difference envelope method, and the structure of the first power supply module are basically the same as the first embodiment, and the main difference is that the voltage difference envelope detection device 11 has a different structure, and is used for acquiring the voltage difference envelope signals of the ship power and the shore power of one phase through the gating of the voltage multiplexer.

Please refer to fig. 14, which is a circuit diagram of a voltage difference envelope detection apparatus in the second embodiment.

Specifically, the voltage difference envelope detection apparatus includes a voltage difference acquisition circuit 0111, an absolute value conversion circuit 0112, and a shaping detection circuit 0113. Two input ends of the voltage difference acquisition circuit 0111 are respectively connected in parallel with two ends of the first switch K2, and voltage difference envelope signals of three-phase power supplies of ship electricity and shore electricity are acquired; the output end of the voltage difference acquisition circuit 0111 is connected with the input end of the absolute value conversion circuit 0112, and the voltage difference envelope signal is transmitted to the absolute value conversion circuit 0112; the output end of the absolute value conversion circuit 0112 is connected with the input end of the shaping detection circuit 0113, and the voltage difference envelope signal is converted into a forward voltage difference envelope signal and then transmitted to the shaping detection circuit 0113; the shaping detection circuit 0113 performs detection processing on the voltage difference envelope signal, converts the voltage difference envelope signal into a periodic forward pulse signal and transmits the periodic forward pulse signal to the control component.

The voltage difference acquisition circuit 0111 comprises six groups of Hall voltage sensor assemblies A1-A6 and a voltage multiplexer D9, wherein one group of Hall voltage sensors acquire ship electricity and shore electricity AU or BV or CW voltage difference signals and transmit the signals to the voltage multiplexer D9; the output end of the voltage multiplexer D9 is connected with the input end of the absolute value conversion circuit 0112, and a voltage difference envelope signal of the corresponding ship electricity and shore electricity is selected through the voltage multiplexer D9 and transmitted to the absolute conversion circuit; the other five groups of Hall voltage sensor groups are used as standby.

And two input ends of the Hall voltage sensor assembly A1 are respectively connected to the U-phase voltage of the A phase and the U-phase voltage of the shore power of the ship power, or respectively connected to the B phase voltage and the V-phase voltage of the shore power of the ship power, or respectively connected to the C phase voltage and the W phase voltage of the shore power of the ship power.

The Hall voltage sensor assembly A1 comprises a wiring seat, 4 third voltage dividing resistors connected in series, two fourth voltage dividing resistors connected in series, a second Hall voltage sensor and a second measuring resistor. The first wiring terminal of the wiring seat is connected to the A-phase voltage of the ship electricity, and the second wiring terminal of the wiring seat is connected to the B-phase voltage of the ship electricity. The first input end of the second Hall voltage sensor is connected with the first wiring terminal of the wiring seat through the 4 series-connection third voltage dividing resistors, and the second input end of the second Hall voltage sensor is connected with the second wiring terminal of the wiring seat through the two series-connection fourth voltage dividing resistors. The output end of the second Hall voltage sensor is connected to the 13 pin of the voltage multiplexer D9 and is grounded through the second measuring resistor.

In addition, the five groups of hall voltage sensor assemblies are identical to the hall voltage sensor assembly A1 in structure and principle, and only differ in the components connected with the input end and the output end, and are not described in detail herein.

And the 16 pins and the 7 pins of the voltage multiplexer are respectively connected with +5V1 voltage and-5V 1 voltage, and the 6 pins and the 8 pins of the voltage multiplexer are grounded. The 11 pin, the 10 pin and the 9 pin of the voltage multiplexer are address ends connected with the singlechip 121, and the input of the three pins is controlled through the singlechip 121, so that the input condition of other pins is controlled, and a corresponding voltage difference envelope signal of ship electricity and shore electricity is output at the 3 pin of the voltage multiplexer.

Specifically, the 11 pin of the voltage multiplexer D9 is connected to +5v1 voltage through the resistor R107, the collector of the triode V37 is connected between the 11 pin of the voltage multiplexer and the resistor R107, the emitter of the triode V37 is grounded, and the base of the triode V37 is connected to the singlechip 121. The 10 pin of the voltage multiplexer D9 is connected to +5v1 voltage through a resistor R109, and is connected to the collector of the triode V37 between the 10 pin of the voltage multiplexer D9 and the resistor R109, the emitter of the triode V37 is grounded, and the base of the triode V37 is connected to the singlechip 121. The 9 pin of the voltage multiplexer D9 is connected to +5v1 voltage through a resistor R111, and is connected to the collector of the triode V37 between the 9 pin of the voltage multiplexer D9 and the resistor R111, the emitter of the triode V37 is grounded, and the base of the triode V37 is connected to the singlechip 121.

The absolute value conversion circuit 0112 and the shaping detection circuit 0113 have the same structure as that of embodiment 1, and a detailed description thereof is omitted.

In this embodiment, the voltage difference envelope detecting device 11' further includes a current obtaining circuit 114', and the current obtaining circuit 114' obtains the current of the ship electricity or the shore power to detect the current state of the ship electricity or the shore power in real time when the ship electricity or the shore power works.

Compared with the prior art, the invention has the advantages that the voltage difference envelope signals of the shore power and the ship power of one phase are gated through the voltage multiplexer, the lowest point of the voltage difference envelope signals is obtained, the docking time period is set according to the lowest point, the closing signal is sent in the docking time period, the seamless docking of the ship power and the ship power is realized under the condition that the ship power is not disconnected, the damage of the circulating current to the variable voltage equipment of the shore power, the generator of the ship and the ship equipment when the ship power is connected with the shore power is effectively prevented, and the normal operation of the shore power, the generator of the ship and the ship equipment is ensured.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.

Claims

1. A shore power connection method for a ship is characterized in that: the method comprises the following steps:

If the variable-voltage variable-frequency power supply and the seamless shore power connection are selected at the same time, the shore power is connected by the smooth switching method in the selected state.

2. The marine shore power hookup method of claim 1, wherein: if the shore power connection based on the voltage difference envelope curve method is selected, after the ship approaches shore, the following steps are executed:

3. The marine shore power hookup method of claim 1, wherein: if the selected state is connected with shore power by following the smooth switching method, after the ship approaches shore, the following steps are executed:

4. A ship connects shore power system which characterized in that: the system comprises an onshore communication module and a judging module;

The judging module is used for:

5. The marine shore power hookup system of claim 4, wherein: the system also comprises a central processing module and a first power supply module; the central processing module receives the selection result of the judging module, and if the shore power is connected based on the voltage difference envelope curve method, the central processing module informs the first power supply module;

6. The marine shore power hookup system of claim 5, wherein: the first power supply module further comprises a first phase sequence switch and a second phase sequence switch which are connected in parallel; the A phase, the B phase and the C phase of the ship electricity are respectively connected with the U phase, the V phase and the W phase of the output end of the shore power transformer through a first phase sequence switch and a first switch; the control assembly further comprises a phase sequence detection device; one end of the phase sequence detection device is connected with the A phase, the B phase and the C phase of the ship electricity respectively, and the other end of the phase sequence detection device is connected with the U phase, the V phase and the W phase of the output end of the shore power transformer respectively so as to detect whether the phase sequences of the ship electricity and the shore power are consistent or not: if the phase sequences are consistent, closing the first phase sequence switch; if the phase sequences are inconsistent, closing a second phase sequence switch;

7. The marine shore power hookup system of claim 4, wherein: the system also comprises a central processing module and a first power supply module; the central processing module receives the selection result of the judging module, and if the selection state is connected with shore power by following the smooth switching method, the central processing module informs the second power supply module;

8. The marine shore power hookup system of claim 7, wherein: the 50Hz line comprises a sixth switch, a seventh switch, a first inductor, a second inductor, a fourth inductor and a first capacitor; the 60Hz line comprises an eighth switch, a third inductor, a fifth inductor and a second capacitor; the public line comprises a fourth resistor, a sixth inductor and a ninth switch;

And the preset power is 5% of rated power of the ship generator.