A ship heavy load starting assistance system

Abstract

The embodiment of the application discloses a ship heavy-load starting auxiliary system, which comprises a PWM inverter, which is used for exciting the excitation winding of a synchronous motor or starting a dynamic fast response program according to a heavy-load power parameter of a heavy-load starting signal within a set time based on a starting command or the heavy-load starting signal, and increasing the excitation of the excitation winding of the synchronous motor to a budget value; an exciter stator, which is used for receiving a frequency-modulated voltage output by the PWM inverter, forming a rotating magnetic field inside the winding, and making the magnetic field vector speed of the exciter stator greater than the motor shaft speed; an exciter rotor on the motor shaft cuts the magnetic field at a set relative speed, and provides excitation current for the excitation winding of the synchronous motor; and a rotating rectifier, which is used for receiving the excitation current, converting the excitation current into direct current through a rectifier bridge, and sending the direct current to the excitation winding of the synchronous motor, so that the excitation winding of the synchronous motor forms a stable N-S two-pole magnetic field around the excitation winding after receiving the direct current, and is pulled into synchronous operation in the alternating rotating magnetic field formed by the synchronous motor stator.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship control, in particular to a ship heavy load starting auxiliary system. BACKGROUND

[0002] Since the ship power supply and distribution system is an independent closed system, the total load is relatively low, and for economic considerations, the total capacity of the power station of ordinary ships is generally only megawatt level, or even lower, while some large motor loads corresponding to ship equipment can reach hundreds of kilowatts. These loads are heavy loads for the ship generator. Since the motor belongs to inductive load, its instantaneous starting (magnetic charging) current has a strong demagnetizing effect on the power generation equipment, which can instantly cause the output voltage of the generator to decrease. Macroscopically, the inductive load with phase angle lag absorbs a large amount of reactive power from the power grid, resulting in a decrease in the voltage of the power grid. When the voltage decreases too much, other loads on the grid may not work normally or even appear under-voltage tripping, and in severe cases, the equipment and system may be damaged.

[0003] In order to solve this problem, at present, star-delta starting, self-coupling transformer starting and soft starting are commonly used in ship power systems. However, there is a certain probability of superimposed large current in the star-delta starting switching process, which causes the instantaneous tripping setting of the circuit breaker to be enlarged to avoid false tripping, and the corresponding thermal protection setting is also passively enlarged. Finally, the size of the power supply cable selected is far beyond the actual working current required, resulting in waste of cost, and sometimes it is difficult to coordinate the protection of the upper and lower circuit breakers; the self-coupling transformer starting has the disadvantage of large size and high heat dissipation requirement, which is not suitable for places with high space utilization rate; the procurement cost of soft starting equipment is very high, and it is not suitable for widespread use.

[0004] At present, for the traditional three heavy load starting methods, there is no essential solution to their respective problems, and they usually adopt a passive adaptation method to meet the requirements. SUMMARY

[0005] In view of the above problems existing in the prior art, the embodiments of the present application provide a ship heavy load starting auxiliary system, which adopts a synchronous motor with dynamically adjustable excitation to access the busbar of the main power distribution cabinet of the ship in no-load state. The synchronous motor dynamically adjusts the rotor excitation in real time according to the heavy load starting signal and the power factor deviation of the power grid, and timely supplements different amounts of reactive power to the ship power grid through different over-excitation states, so as to relieve the voltage drop change caused by the large amount of reactive power absorbed by the large motor load during the starting moment, and the applicability and universality are stronger, and the economy is better.

[0006] The embodiments of the present application provide a ship heavy load starting auxiliary system, which comprises:

[0007] PWM inverter, which is used to increase the excitation of the synchronous motor excitation winding to a budget value based on the ship power grid build-up and the system obtains the start command or at least one heavy load start signal, and start the dynamic fast response program according to the heavy load power parameter corresponding to the at least one heavy load start signal, so that the increased reactive power consumption corresponding to the at least one heavy load start signal is offset by the opposite amount of the synchronous motor instantaneous over-excitation output reactive power increment;

[0008] Exciter stator, which is used to receive the frequency-modulated voltage output by the PWM inverter and form a rotating magnetic field inside the winding, wherein the exciter stator magnetic field vector rotation speed is greater than the motor shaft rotation speed, and the exciter rotor on the motor shaft cuts the formed magnetic field at a set relative speed to provide excitation current for the synchronous motor excitation winding;

[0009] Rotating rectifier, which is used to receive the excitation current generated by the exciter rotor and convert the excitation current into direct current through a rectifier bridge to the synchronous motor excitation winding, so that the synchronous motor excitation winding forms a stable N-S two-pole magnetic field around it after receiving the direct current, and is drawn into synchronous operation in the alternating rotating magnetic field formed by the synchronous motor stator.

[0010] In some embodiments of the present application, the ship heavy load start auxiliary system further comprises:

[0011] Motor start box, which is used to power the PWM inverter and synchronous motor stator after the ship power grid build-up and the system obtains the start command;

[0012] The PWM inverter is particularly used for:

[0013] The control exciter circuit establishes a preliminary start excitation for the synchronous motor excitation winding in the first time length, so that the synchronous motor stator can draw the preliminarily excited rotor into a rotating state after being powered on;

[0014] The PWM inverter combines the power factor feedback signal of the power factor detection circuit to continuously adjust the frequency of the output voltage according to the program setting, and excites the synchronous motor excitation winding through the exciter, so that the synchronous motor can maintain a working state with a power factor of 1.0 after the motor reaches synchronization detected by the rotation speed sensor.

[0015] In some embodiments of the present application, the ship heavy load start auxiliary system further comprises:

[0016] The heavy load starting signal forwarding unit is used to receive the heavy load starting command on the main distribution cabinet of the ship in real time, and sends the heavy load starting command to the PWM inverter through the first line, wherein the heavy load starting signal corresponding to the heavy load starting command is sent to the corresponding starter after the second time length of delay processing in the heavy load starting signal forwarding unit.

[0017] The PWM inverter is also specifically used for:

[0018] The PWM inverter is also specifically used for:

[0019] After the second time length, the heavy load starting signal corresponding to the heavy load starting signal is started, and the reactive power increment of the synchronous motor transient over-excitation output and the reactive power consumption of the heavy load motor suddenly added are superimposed and offset in the opposite direction.

[0020] After that, the PWM inverter gradually reduces the frequency to restore the power factor of the synchronous motor to 1.0, in order to prepare for the next heavy load starting event.

[0021] In some embodiments of the present application, after the PWM inverter receives at least one heavy load starting signal, the power factor deviation value of the power grid is also received through the second line, and the speed signal of the motor shaft is obtained through the third line. The current power factor of the synchronous motor is obtained through the power factor detection line, and after logical judgment and operation of the control module, the inverter circuit provides an alternating voltage with a suitable frequency for the exciter stator, so that a rotating magnetic potential with a speed greater than the speed of the motor shaft is formed in the exciter stator winding, so that the stator magnetic field of the coaxial exciter and the rotor winding of the exciter can actively produce the required relative cutting motion, and a specific current is obtained in the exciter rotor winding.

[0022] In some embodiments of the present application, the motor starting box comprises a motor start-stop control module and a rectifier; wherein,

[0023] The motor start-stop control module realizes the start-stop control of the synchronous motor through the first power line and the remote start-stop line, supplies power to the synchronous motor stator, and provides AC power input for the rectifier, and makes the synchronous motor stator power on after the rectifier is powered on for the first time length

[0024] The motor start-stop control module is provided with a power factor table, which is used to transmit the current power factor and power value of the synchronous motor to the drive control module of the PWM inverter through the power factor detection line, so as to perform corresponding logical control.

[0025] The rectifier is used to provide a DC operating power supply for the inverter.

[0026] In some embodiments of the present application, the ship heavy load starting auxiliary system further comprises:

[0027] A power grid power factor deviation detection unit is used to periodically collect the power grid power factor and operate with a preset standard value to obtain a deviation value which is sent to the PWM inverter through a second line to trigger a static response procedure of reactive power regulation.

[0028] A speed sensor is used to collect the rotating speed of the motor rotating shaft and send it to the PWM inverter through a third line as a reference quantity for logical operation of the output frequency of the PWM inverter.

[0029] In some embodiments of the present application, after the exciter rotor cuts the magnetic field formed by the synchronous motor stator at a set relative speed ΔV, the corresponding size of alternating voltage is determined according to the formula E=B*L*ΔV.

[0030] In some embodiments of the present application, the synchronous motor stator obtains voltage U from the power grid through a second power line, and after entering the synchronous running state, the vector diagram formed by the excitation magnetic potential E0 of the synchronous motor rotor excitation winding and the U phase angle leading E0 forms a positive power angle δ.

[0031] In the case of over-excitation, the excitation magnetic potential E0 of the synchronous motor rotor excitation winding is greater than the grid voltage U, which promotes the current I in the synchronous motor stator to lead the grid voltage U by an angle φ.

[0032] In some embodiments of the present application, the ship heavy load starting auxiliary system further comprises:

[0033] An intermediate isolation cavity is used to physically insulate and isolate the synchronous motor stator and the synchronous motor rotor excitation winding from the coaxial exciter stator and the exciter rotor.

[0034] Compared with the prior art, the ship heavy load starting auxiliary system provided by the embodiment of the application has the beneficial effects that: in view of the characteristics of the ship power load sequential starting, different heavy loads will be started in batches, the single moderate-capacity heavy load starting auxiliary system can meet the demand of starting of all heavy loads of the ship in time periods after being started first, Y-Δ starting, self-coupling transformer starting, soft starting and other starting modes will not be needed, the cost of purchasing the equipment is greatly reduced, and the layout space of the electrical equipment is also saved, and the power distribution equipment is more flexible to combine and arrange; meanwhile, the synchronous motor reactive power output is adjusted in the PWM frequency conversion mode, the dynamic response is rapid, and the short board of poor instantaneous voltage regulation capacity of the power grid can be well made up; further, through the function design of static adjustment and optimization of the power grid reactive power, the power grid transmission efficiency can be improved, and the burden of the generator equipment can be appropriately reduced, and the economic benefit of the equipment is prolonged; in addition, the rectifier equipment and the inverter equipment in the above technical solution are installed separately, and the heat dissipation problem of the electronic equipment is well solved. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A ship heavy load starting auxiliary system provided by the embodiment of the application and a principle diagram of a ship power grid;

[0036] Figure 2 A principle diagram of the ship heavy load starting auxiliary system provided by the embodiment of the application;

[0037] Figure 3 A working principle of a PWM inverter in the ship heavy load starting auxiliary system provided by the embodiment of the application;

[0038] Figure 4 An electrical parameter vector diagram of a synchronous motor in the ship heavy load starting auxiliary system provided by the embodiment of the application;

[0039] Figure 5 A running program flowchart of the ship heavy load starting auxiliary system provided by the embodiment of the application.

[0040] REFERENCE NUMERALS

[0041] 1, synchronous motor stator; 2, synchronous motor excitation winding; 3, PWM inverter;

[0042] 31, first line; 32, second line; 33, third line; 34, power factor detection line;

[0043] 4, exciter stator; 5, exciter rotor; 6, rotary rectifier; 7, speed sensor;

[0044] 8, intermediate isolation cavity; 9, motor starting box; 91, motor start-stop control module; 92, rectifier;

[0045] 93 first power line; 94 second power line; 95 remote start / stop line

[0046] 10 heavy load start signal forwarding unit; 11 power factor deviation detection unit. DETAILED DESCRIPTION

[0047] For those skilled in the art to better understand the technical solutions of the present application, the present application will be described in detail below in combination with the drawings and specific embodiments.

[0048] The various aspects and features of the present application are described herein with reference to the accompanying drawings.

[0049] These and other characteristics of the present application will become apparent from the following description of the preferred forms given, by way of non-limiting example, with reference to the attached drawings.

[0050] It should also be understood that, although the present application has been described herein with reference to certain specific examples, various modifications thereof will be readily apparent to those skilled in the art with the sole proviso that a claim determined as such has characteristics as claimed and is therefore within the scope of protection defined thereby.

[0051] The above and other aspects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

[0052] Specific embodiments of the present application are described hereinafter with reference to the accompanying drawings; however, it is to be understood that the embodiments described are merely examples of the present application, which can be embodied in various forms. Well-known and / or redundant functions and structures are not described in detail in order to avoid obscuring the present application in unnecessary or redundant details. Therefore, specific structural and functional details disclosed herein are not intended to limit the present application but only serve as a representative basis for teaching one of ordinary skill in the art to variously employ the present application in virtually any appropriate detailed structure.

[0053] The specification can use phrases such as "in one embodiment", "in another embodiment", "in yet another embodiment", or "in other embodiments", which can refer to one or more of the same or different embodiments of the application.

[0054] The present embodiment provides a ship heavy load start auxiliary system, as shown in the accompanying drawings, the system comprises: Figures 1 to 5

[0055] ​PWM inverter 3, which is used to excite the synchronous motor field winding 2 to a preset value based on the ship power grid voltage and system start command, or at least one heavy load start signal, and to start the dynamic fast response program according to the heavy load power parameter corresponding to the at least one heavy load start signal, so that the increased reactive power consumption corresponding to the at least one heavy load start signal is offset by the reactive power increment output by the synchronous motor over-excitation.

[0056] Exciter stator 4, which is used to receive the frequency-modulated voltage output by the PWM inverter 3 and form a rotating magnetic field inside the winding, wherein the exciter stator 4 magnetic field vector rotates at a speed greater than the motor shaft speed, and the exciter rotor 5 on the motor shaft cuts the formed magnetic field at a set relative speed, providing excitation current for the synchronous motor field winding 2; that is, the exciter rotor 5 coil cuts the magnetic induction lines under the action of the speed difference, forming an alternating voltage, which provides the source of excitation current for the synchronous motor field winding 2; after the exciter rotor 5 specifically cuts the magnetic field formed by the synchronous motor stator 1 at a set relative speed ΔV, the corresponding size of the alternating voltage is determined according to the formula E=B*L*ΔV, that is, the higher the frequency of the voltage output by the PWM inverter 3 to the exciter stator 4, the greater the ΔV, and the higher the potential formed in the exciter rotor 5.

[0057] Rotating rectifier 6, which is used to receive the excitation current generated by the exciter rotor 5 and convert the excitation current into direct current through a rectifier bridge and send it to the synchronous motor field winding 2, so that the synchronous motor field winding 2 forms a stable N-S two-pole magnetic field around it after receiving the direct current, and is pulled into synchronous operation in the alternating rotating magnetic field formed by the synchronous motor stator 1.

[0058] In the above embodiment, the synchronous motor stator 1 obtains voltage U from the power grid through the second power line 94, and after entering the synchronous operation state, in the vector diagram formed by the excitation magnetic potential E0 of the synchronous motor rotor field winding, specifically referring to Figure 4 , the U phase angle leads E0 to form a positive power angle δ, that is, the motor absorbs a certain active power to overcome the friction resistance and copper loss of the synchronous motor no-load to maintain the synchronous speed; in the case of over-excitation of the synchronous motor rotor field winding, the excitation magnetic potential E0 is greater than the grid voltage U, which causes the current I in the synchronous motor stator 1 to lead the grid voltage U (similar to a capacitive load) by one phase angle φ, that is, the synchronous motor sends U*I*sinφ=Q reactive power to the grid. In the rated value range, the greater the excitation magnetic potential E0, the greater the reactive power Q delivered by the synchronous motor to the grid.

[0059] In this embodiment, the ship heavy load start auxiliary system further comprises:

[0060] a motor starting box 9 for supplying power to the PWM inverter 3 and the synchronous motor stator 1 after the ship power grid is built up and a system starting command is received;

[0061] The PWM inverter 3 is specifically configured to: control the exciter motor circuit to establish a preliminary starting excitation for the synchronous motor excitation winding 2 within a first time length, so that the synchronous motor stator 1 can pull the preliminarily excited rotor into a rotating state after being powered; and in combination with a power factor feedback signal of the power factor detection circuit 34, the PWM inverter 3 adjusts the frequency of the output voltage according to a program setting, and excites the synchronous motor excitation winding 2 through the exciter motor, so that the synchronous motor is maintained in a working state with a power factor of 1.0 after the motor reaches synchronization detected by the speed sensor 7.

[0062] In the embodiment, the ship heavy-load starting auxiliary system further comprises:

[0063] A heavy-load starting signal forwarding unit 10 is configured to receive a heavy-load (automatic / manual) starting command on a ship main power distribution cabinet in real time, and send the heavy-load starting command to the PWM inverter 3 through a first circuit 31 to trigger a quick dynamic response program of reactive power regulation, wherein the heavy-load starting signal corresponding to the heavy-load starting command is sent to a corresponding starter after being processed by the heavy-load starting signal forwarding unit 10 for a second time length. The second time length provides a logical control response time for the PWM inverter 3, so that the synchronous motor reactive power supply response and the sudden reactive power demand of the heavy-load are synchronized, and the regulation oscillation period is reduced.

[0064] The PWM inverter 3 is further specifically configured to:

[0065] The PWM inverter 3 is further specifically configured to:

[0066] In the embodiment, after the PWM inverter 3 receives at least one heavy load starting signal, it also receives the power factor deviation value of the power grid through the second line 32, and obtains the rotating speed signal of the motor shaft through the third line 33, obtains the current power factor of the synchronous motor through the power factor detection line 34, and after logical judgment and operation of the control module, provides the exciter stator 4 with alternating voltage of appropriate frequency through the inverter circuit, so that the rotating magnetic potential in the exciter stator 4 winding is formed, which has a rotating speed greater than that of the motor shaft, so that the stator magnetic field of the coaxial exciter and the rotor winding of the exciter can actively produce the required relative cutting motion, and a specific current is obtained in the exciter rotor 5 winding.

[0067] Further, in the embodiment, the motor starting box 9 comprises a motor start-stop control module 91 and a rectifier 92; wherein,

[0068] The motor start-stop control module 91 synchronously controls the start and stop of the motor through the first power line 93 and the remote start-stop line 95, supplies power to the synchronous motor stator 1, provides AC power input for the rectifier 92, and through delay control, makes the synchronous motor stator 1 be powered after the rectifier 92 is powered and the first time length; so that the synchronous motor has enough time to establish preliminary excitation for the synchronous motor excitation winding 2 at the initial start;

[0069] The motor start-stop control module 91 is provided with a power factor table, which is used to transmit the current power factor and power value of the synchronous motor to the drive control module of the PWM inverter 3 through the power factor detection line 34, for the corresponding logical control of the PWM inverter 3;

[0070] The rectifier 92 is used to provide DC working power for the inverter, and the electronic device rectifier 92 and the PWM inverter 3 are respectively installed at two different positions to better dissipate heat.

[0071] In the embodiment, the ship heavy load starting auxiliary system further comprises:

[0072] The power grid power factor deviation detection unit 11 is used to periodically collect the power factor of the power grid and operate with the preset standard value to obtain the deviation value, which is sent to the PWM inverter 3 through the second line 32 to trigger the static response program of reactive power regulation;

[0073] The rotating speed sensor 7 is used to collect the rotating speed of the motor shaft and send it to the PWM inverter 3 through the third line 33 as a reference quantity for the logical operation of the output frequency of the PWM inverter 3.

[0074] In the embodiment, the ship heavy load starting auxiliary system further comprises an intermediate isolation chamber 8 for physically insulating and isolating the synchronous motor stator 1 and the synchronous motor rotor excitation winding from the coaxial exciter stator 4 and the exciter rotor 5, so that they work independently and are not disturbed.

[0075] In order to facilitate the understanding of the above technical solutions, the basic operation principle of the above embodiment is described as follows. Figure 5 As shown in the following figure, the specific process is as follows:

[0076] After the ship power grid is built and the system receives a starting command, the motor starting box 9 supplies power to the PWM inverter 3 and the synchronous motor stator 1 in sequence. The exciter motor electric circuit controlled by the PWM inverter 3 establishes a preliminary starting excitation for the synchronous motor excitation winding 2 within a first time length. Then, the synchronous motor stator 1 is powered and the initially excited rotor is pulled into a rotating state. In combination with the power factor feedback signal of the power factor detection circuit 34, the PWM inverter 3 continuously adjusts the frequency of the output voltage according to the program setting, and the exciter motor excites the synchronous motor excitation winding 2. Finally, when the motor reaches synchronization detected by the speed sensor 7, the synchronous motor will maintain a working state with a power factor of 1.0, that is, it does not absorb or output reactive power. At this time, the system will enter a standby listening mode to listen to the heavy load starting signal of the ship power grid and the fluctuation (static deviation) of the power grid power factor.

[0077] When the heavy load starting signal forwarding unit 10 detects the n number (or multiple) heavy load starting signals in the ship power grid (main power distribution cabinet), it is temporarily forwarded to the PWM inverter 3 through the first circuit 31. The inverter will start the dynamic fast response program according to the n number (or multiple) heavy load power parameters preset in the program within a second time length, and start to increase the synchronous motor excitation to a suitable preset value. At the same time, after a delay of the second time length, the heavy load n is directly started. At this time, the reactive power increment of the synchronous motor instantaneous over-excitation output and the reactive power consumption of the sudden increase of the heavy load motor n are just opposite vector superposition, which will ensure that only a small voltage fluctuation will occur in the main bus of the ship power grid, making up for the short board that the power generation equipment cannot respond instantly to the sudden load, and ensuring the continuous and normal operation of the ship power grid. After that, the heavy load starting auxiliary system will continuously and slowly reduce the reactive power output (i.e. the PWM inverter 3 gradually reduces the frequency), until the power factor of the synchronous motor is restored to 1.0, in order to prepare for the next heavy load starting event. During this period, the automatic speed regulation and voltage regulation equipment of the ship power generation equipment will continuously adjust the active and reactive power output until the frequency and voltage of the power grid are stabilized within a specified range.

[0078] After the grid-connected starting of the certain heavy load n is processed, the system will enter the static response procedure, which will collect the ship power grid power factor deviation value through the second line 32, when judging that the steady-state deviation value is too large, the PWM inverter 3 of the system will adjust the frequency output again to change the excitation of the synchronous motor excitation winding 2, and then change the reactive power output to the power grid, until the power factor of the ship power grid returns to the ideal preset range, the adjustment process can be used as a supplement to the generator AVR function, which can optimize the power factor of the power grid, thereby improving the transmission efficiency of the power grid, and in the extreme case (when the overall power factor of the ship motor load is low), it can avoid the overheat working condition of the winding caused by the long-term magnetic saturation of the generator equipment as a reactive power supplement device.

[0079] After the above dynamic and static adjustment process is completed, the system will enter the listening state again.

[0080] Through the above technical scheme, it can be known that the ship heavy load starting auxiliary system provided by the above embodiment of the application combines the characteristics of the sequential starting of the ship power load, different heavy loads will be started in batches, and the single heavy load starting auxiliary system with moderate capacity can meet the demand of starting all heavy loads of the ship in time periods after being started, Y-Δ starting, autotransformer starting, soft starting and other starting modes will no longer be needed, which greatly reduces the purchase cost of the equipment and is also beneficial to saving the layout space of the electrical equipment, facilitating the flexible combination and arrangement of the power distribution equipment; at the same time, the synchronous motor reactive power output is adjusted by using the PWM frequency conversion mode, the dynamic response is rapid, and the short board of poor instantaneous voltage regulation capacity of the power grid can be well made up; further, through the function design of static adjustment and optimization of the power grid reactive power, not only the transmission efficiency of the power grid can be improved, but also the burden of the generator equipment can be appropriately reduced, and the economic benefit of the equipment can be prolonged; in addition, the rectifier equipment and the inverter equipment involved in the above technical scheme are installed separately, which well solves the heat dissipation problem of the electronic equipment.

[0081] The above embodiments are only exemplary embodiments of the application and are not used to limit the application, and the protection scope of the application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the application within the spirit and protection scope of the application, and such modifications or equivalent replacements are also regarded as falling within the protection scope of the application.

Claims

1. A ship heavy-load start-up assistance system, characterized in that, include: A PWM inverter is used to excite the synchronous motor excitation winding within a corresponding set time based on the voltage establishment of the ship's power grid and the system receiving a start command, or at least one heavy-load start signal, or to start a dynamic fast response program according to the heavy-load power parameters corresponding to the at least one heavy-load start signal, so as to increase the excitation of the synchronous motor excitation winding to a budget value, so that the reactive power consumption increased by the heavy-load start corresponding to the at least one heavy-load start signal is offset by the reactive power increment of the instantaneous overexcitation output of the synchronous motor. The exciter stator is used to receive the frequency-modulated voltage output by the PWM inverter and form a rotating magnetic field inside the winding. The magnetic field vector speed of the exciter stator is greater than the motor shaft speed. The exciter rotor on the motor shaft cuts the formed magnetic field at a set relative speed to provide excitation current to the excitation winding of the synchronous motor. A rotating rectifier receives the excitation current generated by the exciter rotor and converts it into direct current through a rectifier bridge, which is then sent to the excitation winding of the synchronous motor. This allows the excitation winding to form a stable N-S polarity magnetic field around itself after receiving the direct current, thus inducing synchronous operation within the alternating rotating magnetic field formed by the stator of the synchronous motor. The heavy load start signal forwarding unit is used to receive the heavy load start command from the ship's main power distribution cabinet in real time and send it to the PWM inverter through the first line. The heavy load start signal corresponding to the heavy load start command is sent to its respective starter after being delayed for a second time in the heavy load start signal forwarding unit. The PWM inverter is also specifically used for: The system receives at least one heavy-load start signal through the first line, and within the second time period, it initiates a dynamic fast response program based on the heavy-load power parameters corresponding to the at least one heavy-load start signal to increase the excitation of the synchronous motor excitation winding to the budget value. After the second duration, the heavy load corresponding to the at least one heavy load start signal starts, and the reactive power increment of the synchronous motor instantaneous overexcitation output and the reactive power consumption of the heavy load motor corresponding to the at least one heavy load start signal are superimposed and offset by the reverse vector superposition. Subsequently, the PWM inverter gradually reduces its frequency until the power factor of the synchronous motor is restored to 1.0, in preparation for the next heavy-load start-up event.

2. The ship heavy-load start-up assistance system according to claim 1, characterized in that, Also includes: The motor starter box is used to supply power to the PWM inverter and the synchronous motor stator after the ship's power grid is powered up and the system receives a start command; The PWM inverter is specifically used for: The control exciter electrical circuit establishes initial starting excitation for the synchronous motor excitation winding within the first time period, so that the synchronous motor stator can pull the initially excited rotor into a rotating state after being energized. The PWM inverter, combined with the power factor feedback signal from the power factor detection circuit, continuously adjusts the frequency of the output voltage according to the program settings. It excites the excitation winding of the synchronous motor through the exciter, so that after the speed sensor detects that the motor has reached synchronization, the synchronous motor is kept in a working state with a power factor of 1.

0.

3. The ship heavy-load start-up assistance system according to claim 2, characterized in that, After the PWM inverter receives at least one heavy-load start signal, it also receives the power factor deviation value of the power grid through the second line and obtains the speed signal of the motor shaft through the third line. It obtains the current power factor of the synchronous motor through the power factor detection line. After the control module makes logical judgments and calculations, it provides an alternating voltage of appropriate frequency to the exciter stator through the inverter circuit, so that a rotating magnetomotive force with a speed greater than the motor shaft speed is formed in the exciter stator winding. This allows the stator magnetic field of the coaxial exciter to actively generate the required relative cutting motion with the rotor winding of the exciter, and obtains a specific current in the exciter rotor winding.

4. The ship heavy-load start-up assistance system according to claim 3, characterized in that, The motor starter box includes a motor start / stop control module and a rectifier; wherein... The motor start-stop control module realizes the start-stop control of the synchronous motor through the first power line and the remote start-stop line, supplies power to the stator of the synchronous motor, provides AC power input to the rectifier, and through delay control, ensures that the stator of the synchronous motor is energized after the rectifier is energized and then after the first time period. The motor start / stop control module is equipped with a power factor meter, which is used to transmit the current power factor and power value of the synchronous motor to the drive control module of the PWM inverter through the power factor detection line for corresponding logic control. The rectifier is used to provide DC operating power to the inverter.

5. The ship heavy-load start-up assistance system according to claim 4, characterized in that, Also includes: The power factor deviation detection unit is used to periodically collect the power factor of the power grid and calculate it with a preset standard value. The resulting deviation value is sent to the PWM inverter via the second line to trigger the reactive power regulation static response program. A speed sensor is used to collect the rotational speed of the motor shaft and send it to the PWM inverter via a third line as a reference for the logical operation of the output frequency of the PWM inverter.

6. The ship heavy-load start-up assistance system according to claim 5, characterized in that, The exciter rotor cuts the magnetic field formed by the synchronous motor stator at a set relative speed ΔV, and then determines the corresponding AC voltage according to the formula E=B*L*ΔV.

7. The ship heavy-load start-up assistance system according to claim 6, characterized in that, The stator of the synchronous motor obtains voltage U from the power grid through the second power line. After entering the synchronous operation state, the vector diagram formed by the excitation magnetomotive force E0 of the excitation winding of the synchronous motor rotor shows that the phase angle U leads E0 to form a positive power angle δ. When the rotor excitation winding of the synchronous motor is overexcited, the excitation magnetomotive force E0 is greater than the grid voltage U, causing the current I in the stator of the synchronous motor to lead the grid voltage U by a phase angle φ.

8. The ship heavy-load start-up assistance system according to claim 7, characterized in that, Also includes: The intermediate isolation cavity is used to physically insulate and isolate the excitation windings of the synchronous motor stator and the synchronous motor rotor from the coaxial exciter stator and the exciter rotor.

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