Distributed monitoring of embedded quasi-synchronous parallel operation low voltage ac power control system

Abstract

The application relates to a kind of distributed monitoring embedded quasi-synchronous parallel operation low-voltage alternating current power control systems, including power monitoring unit, display control unit and multiple unit controllers;Unit controller collects the operation and grid parameters of generator set, sends to power monitoring unit and other unit controllers, and controls the start-stop, speed regulation and main switch closing and opening of generator set;Power monitoring unit receives the operation and grid parameters of unit controller, generates cooperative control instruction and issues to unit controller;When parallel operation is needed, control the automatic voltage regulation and speed regulation of standby parallel operation generator set, and control the closing of main switch of standby parallel operation generator set;When multiple generator sets are operated in parallel, the active / reactive power of each unit is obtained, the unit with high power is controlled to slow down and step up and / or the unit with low power is controlled to speed up and step down, to realize the automatic equalization distribution of active / reactive power among parallel units.The application improves the control accuracy, automation level and stability when multiple generator sets are operated in parallel.

Description

Technical Field

[0001] This invention relates to the field of automated control technology for ship power plants, and in particular to a distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system. Background Technology

[0002] The ship's electrical system is the core guarantee for the safe and stable operation of a ship, and the performance of its control system is directly related to the reliability of the ship's power supply. In order to improve power supply capacity, reliability and redundancy, multiple generator sets are usually configured in the ship's electrical system, and the generator sets need to be put into operation, taken out of operation or operated in parallel according to load changes.

[0003] Currently, existing ship power control systems suffer from insufficient precision and automation in achieving parallel operation of multiple generator units. Traditional control methods rely heavily on independent dedicated synchronization devices (parallel operation devices) and distributed control units. The lack of efficient and reliable data exchange and collaborative decision-making mechanisms between these control units makes it difficult to quickly and accurately match and adjust parameters such as voltage, frequency, and phase of each generator unit during parallel operation, thus affecting the smoothness and success rate of the parallel operation. After parallel operation, the system struggles to achieve stable and balanced distribution of active power among the units when the load changes dynamically, easily leading to power oscillations or uneven distribution, affecting the stability of the power grid frequency and the lifespan of the generator units. Furthermore, existing systems have limited automation in key processes such as parallel operation and load distribution, often requiring frequent operator intervention. This not only increases operational complexity but also introduces the risk of system instability due to human error or operational delays. Summary of the Invention

[0004] Therefore, it is necessary to provide a distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system to address the problems of low paralleling accuracy, poor power distribution stability, and reliance on manual operation caused by poor coordination between control units, reliance on independent devices, and insufficient automation in traditional systems.

[0005] The present invention provides a distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system, the system comprising a power monitoring unit, at least two display and control units, and multiple generator controllers corresponding to multiple generator sets respectively. The power monitoring unit, the display and control unit, and the unit controller are connected via dual CAN bus communication. The dual CAN bus adopts physically isolated A / B redundant channels. The unit controller is embedded in the drawer-type functional compartment of the ship's main power distribution board. The display and control unit is embedded in the inside of the cabinet door of the main power distribution board. The display and control unit includes a ruggedized touch display and physical control buttons. The electromagnetic shielding layer of the ruggedized touch display and the metal cabinet of the main power distribution board form a continuous shield through conductive pads. The generator unit controller is used to collect the operating parameters and grid parameters of the corresponding generator unit in real time. The operating parameters include generator speed, active power, reactive power, power factor, and winding temperature. The grid parameters include grid voltage, current, frequency, and phase. The controller transmits the operating parameters and grid parameters to the power monitoring unit and other generator unit controllers through the A / B dual-channel redundancy of the dual CAN bus. The controller is also used to receive control commands from the power monitoring unit or display and control unit. The control commands include speed regulation pulse width modulation signals, voltage regulation duty cycle signals, and main switch opening and closing trigger signals. The controller then performs start-up, speed regulation, and main switch opening and closing control on the corresponding generator unit. The power monitoring unit is used to receive operating parameters and grid parameters from each unit controller via the dual CAN bus, centrally process the operating parameters based on a preset dynamic priority arbitration algorithm, generate collaborative control commands for unit parallel operation control, and send them to the corresponding unit controllers via the dual CAN bus. The dynamic priority arbitration algorithm includes: when a reload inquiry signal and a fault disconnection request signal are received concurrently, the load transfer of the faulty unit is executed first, and the reload start sequence is suspended. When a generator set to be connected to an existing power grid needs to be connected, the power monitoring unit and the corresponding generator controller work together. Based on the voltage difference, frequency difference, and phase difference between the power grid and the generator set to be connected, which are collected in real time by the generator controller, the generator controller controls the generator set to be connected to perform automatic voltage and speed regulation. The automatic voltage and speed regulation includes: automatically performing voltage regulation operation in response to the voltage difference not meeting the requirements; controlling the generator set to be connected to accelerate in response to the frequency difference being negative; controlling the generator set to be connected to decelerate in response to the frequency difference being positive and greater than a preset frequency value; and after both the voltage difference and frequency difference meet the requirements, performing phase condition judgment, and issuing a connection closing command when the phase condition is met and the connection condition detection time is less than a preset time, to achieve quasi-synchronous connection. During the parallel operation of multiple generator units, the power monitoring unit calculates the power distribution difference based on the active / reactive power of each unit acquired through the dual CAN bus, and generates load adjustment commands. The generation of these load adjustment commands follows a frequency-power dual closed-loop coupled control strategy: when the grid frequency is within the required range but the power distribution difference exceeds the required range, the higher-power generator unit is controlled to decelerate while the lower-power generator unit is controlled to accelerate; when the grid frequency is below a first frequency threshold, if the active / reactive power distribution difference is within the allowable range, all parallel generator units are controlled to accelerate simultaneously; if it exceeds the allowable range, the lower-power generator unit is controlled to accelerate first; when the grid frequency is above a second frequency threshold, if the active / reactive power distribution difference is within the allowable range, all parallel generator units are controlled to decelerate simultaneously; if it exceeds the allowable range, the higher-power generator unit is controlled to decelerate first. This achieves automatic balanced distribution of active / reactive power among the parallel generator units and maintains the grid frequency stable within the range of 50±0.25Hz during load adjustment.

[0006] In one embodiment, the system further includes a shore power controller and a jumper controller, which are connected to the power monitoring unit via A / B dual-channel redundant communication of the dual CAN bus. The shore power controller is configured to: send shore power parameters to the power monitoring unit through channel A when it receives a shore power input command; automatically switch to channel B when channel A fails; and issue a prohibition signal for parallel operation to the unit controller through hardwiring when both channels fail.

[0007] In one embodiment, the step of controlling the generator set to be paralleled to perform automatic voltage and speed regulation based on the voltage difference, frequency difference, and phase difference between the power grid and the generator set to be paralleled, which are collected in real time by the generator set controller, includes: In response to the absolute value of the voltage difference being greater than a preset voltage threshold, the unit controller outputs a voltage regulation duty cycle signal to the automatic voltage regulator to perform automatic voltage regulation. The preset voltage threshold is ±5% of the rated voltage. In response to a frequency difference that is negative and less than -0.1Hz, a speed regulation pulse width modulation signal is output to the electronic speed governor to control the acceleration of the generator set to be paralleled; In response to a frequency difference that is positive and greater than +0.3Hz, the generator set to be paralleled is controlled to decelerate; After both the voltage difference and frequency difference meet the requirements, the phase difference change rate is calculated based on the real-time measured frequency difference to predict the phase overlap time point within the next 3-5 seconds. A closing preparation command is issued 200ms before the phase overlap time point, and a parallel closing command is issued when the actual phase difference is detected to be less than 5° and the absolute value of the frequency difference is less than 0.1Hz.

[0008] In one embodiment, the system is used to perform automatic generator set disconnection and shutdown control, and works in conjunction with the dynamic priority arbitration algorithm, specifically including: If a general fault occurs in a unit during stand-alone operation, the power monitoring unit will pause responding to any heavy load inquiry signals, prioritize starting the standby unit, execute the automatic paralleling procedure, and after successful paralleling, control the faulty unit to decelerate and control the stationary unit to accelerate through the unit controller. When the active power of the faulty unit is less than the preset value for disconnection, it will issue a trip command and issue a shutdown command after a delay. When operating in parallel, if the active power of a certain unit is less than 20% of the rated power and the delay time is reached, the unit is determined to be a unit to be disconnected. The unit to be disconnected is controlled to decelerate, and the units remaining on the grid are controlled to accelerate. When the active power of the unit is less than 5% of the rated power, its tripping command is issued and a shutdown command is issued after a delay. When a serious malfunction occurs in the unit, a shutdown command is directly issued for the unit, and a fault code is broadcast through the dual CAN bus, triggering the LED indicator of the physical control button of the display and control unit to flash red as an alarm.

[0009] In one embodiment, the system is further configured to perform overload query control and to work in conjunction with the dynamic priority arbitration algorithm, specifically including: Receive heavy load inquiry signals from the ship's active power control system or integrated bridge and calculate the power grid's remaining active power. The calculation includes the sum of the rated power of the currently operating units minus the actual load power and then minus the power reserve margin. If the remaining active power meets the heavy load start-up conditions, a start-up permission signal is sent to the load controller via the dual CAN bus. If the remaining active power does not meet the heavy load start-up conditions and there are still standby units that are not in operation, an additional unit prompt will be issued and the automatic paralleling procedure and automatic frequency regulation and load adjustment procedure will be started in sequence. During the additional unit process, the execution of any unit disconnection and shutdown command will be suspended. If the remaining active power does not meet the heavy load start-up conditions and no backup unit is available, a heavy load start-up rejection signal will be sent through the dual CAN bus after a 30-second delay, and an audible and visual alarm will be issued. At the same time, the grid status will be fed back to the active power control system.

[0010] In one embodiment, the power monitoring unit runs on a ruggedized computer and provides a human-machine interface, the human-machine interface including: The single-line schematic interface displays the A / B channel communication status and redundancy switching count of the dual CAN bus in real time. The unit priority standby order setting interface allows operators to set the unit priority through the ruggedized touch display, and automatically adjusts the priority when a unit failure is detected. The unit status monitoring interface displays the installation location temperature, electromagnetic shielding status, and communication error rate of each unit controller. The power grid monitoring information interface displays the real-time adjustment amount of the frequency-power dual closed-loop coupling control strategy; The network status monitoring interface displays the status and heartbeat signals of the dual CAN bus nodes of the power monitoring unit, display and control unit, and unit controller.

[0011] In one embodiment, the power monitoring unit is further configured to communicate with the ship's main power control system and integrated bridge via Ethernet to receive heavy load inquiry signals and feedback the power grid status using the Modbus TCP / IP protocol. Simultaneously, it receives hard-wired emergency stop signals from the display and control unit via the dual CAN bus, wherein the hard-wired emergency stop signals have a higher priority than the Ethernet control commands.

[0012] In one embodiment, the system is also used to perform single-unit frequency regulation control. When the power grid is operating as a single unit, the power monitoring unit switches to single-unit frequency stabilization mode. If the power grid frequency is detected to be lower than a first frequency threshold, the online operating unit is controlled to accelerate. If the power grid frequency is detected to be higher than a second frequency threshold, the online operating unit is controlled to decelerate.

[0013] In one embodiment, the dual-CAN bus A / B dual-channel redundant communication includes: when the unit controller sends data, it simultaneously sends data frames with the same frame ID to both channel A and channel B; the power monitoring unit simultaneously receives data from both channel A and channel B and judges the data consistency through a bit-by-bit comparison algorithm; when a certain channel is detected to have CRC check errors or data inconsistency for three consecutive times, the channel is marked as a faulty channel and switched to another channel; at the same time, the display and control unit displays a channel fault alarm.

[0014] In one embodiment, the generation of the cooperative control command further includes: The power monitoring unit establishes a power-speed characteristic curve based on the historical operating data of each unit. Before generating the load adjustment command, it first queries the characteristic curve to determine the current efficiency range of each unit, prioritizes adjusting the units in the low efficiency range, and avoids the vibration speed restriction range of each unit. The vibration speed restriction range is 45%-55% and 85%-95% of the rated speed.

[0015] The aforementioned distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system collects real-time operating parameters of each generator set and the power grid through the unit controller. It utilizes a highly reliable dual CAN bus to achieve real-time sharing and interaction of system-wide operating data between control units, providing a data foundation for centralized collaborative decision-making. Based on this, the power monitoring unit performs unified calculations and generates collaborative control commands based on global data. During parallel operation, it compares the voltage, frequency, and phase difference between the power grid and the generator set to be paralleled in real time, and performs closed-loop control of the generator set to be paralleled for automatic voltage and speed regulation until the quasi-synchronous conditions are met before closing the circuit. This process eliminates the dependence on independent dedicated synchronization devices, achieving fast and accurate automatic quasi-synchronous parallel operation. During parallel operation, the power monitoring unit continuously calculates the distribution difference of active / reactive power among the generator sets and drives the unit controllers to decelerate and increase voltage for high-power generator sets and accelerate and decrease voltage for low-power generator sets through commands, forming a closed-loop control. This achieves automatic, stable, and balanced distribution of active / reactive power among the parallel generator sets when the load dynamically changes, effectively suppressing power oscillations and frequency fluctuations. The high degree of automation in the entire paralleling and power distribution process reduces reliance on manual operation and lowers the operational complexity and instability risks caused by human factors, thereby improving the overall control accuracy, automation level and system stability when multiple generator sets are running in parallel. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system of the present invention. Figure 2 This is a flowchart of the generator set self-starting control of the present invention; Figure 3 This is a flowchart of the automatic parallel control process of the present invention; Figure 4 This is a flowchart of the multi-unit frequency regulation and load control process of the present invention; Figure 5 This is a flowchart of the single-unit frequency regulation control of the present invention; Figure 6 This is a flowchart of the automatic disconnection and shutdown control process of the present invention; Figure 7 This is a flowchart of the overloaded interrogation control of the present invention.

[0018] Figure label: 110. Power monitoring unit; 120. Display and control unit; 130. Unit controller. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this specification are for illustrative purposes only and do not represent the only possible implementation.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0024] The following is combined Figures 1-7 This invention describes a distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system.

[0025] like Figure 1As shown, in one embodiment, a distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system includes a power monitoring unit 110, at least two display and control units 120, and multiple generator controllers 130 corresponding to multiple generator sets. The power monitoring unit 110, display and control units 120, and generator controllers 130 are connected via dual CAN buses to form a distributed control network. The power monitoring unit 110 is located in the central control room, and the multiple generator sets are located in the auxiliary engine room. The generator controllers 130 are used to collect the operating parameters of the corresponding generator sets and the grid parameters in real time, and send the data to the power monitoring unit 110 and other generator controllers via dual CAN buses. At the same time, they receive instructions from the power monitoring unit 110 or the display and control units 120 to execute the start-up, shutdown, speed regulation, and main switch (such as the main switches of generator sets 1#, 2#, 3#, and 4#) opening and closing control of the generator sets 130. The display and control unit 120 (such as display and control units #1 and #2) and the unit controller 130 (such as unit controllers #1, #2, #3, and #4) are integrated into the ship's main switchboard (such as main switchboards #1 and #2) using a recessed design. The display and control unit 120 is equipped with a ruggedized touch display and physical control buttons to realize semi-automatic operation of the power station, remote control of the generator sets, and display of important parameters. The dual CAN bus adopts a physically isolated A / B redundant channel design. When sending data, the unit controller 130 simultaneously sends data frames with the same frame ID (such as 0x400-0x4FF for unit status and 0x500-0x5FF for control commands) to both the A and B channels. The power monitoring unit 110 receives data from both the A and B channels simultaneously through two independent CAN interfaces and determines data consistency through a bit-wise comparison algorithm. When a channel is detected to have three consecutive CRC check errors or inconsistent data (e.g., channel A data is 0x01 while channel B data is 0x81), the power monitoring unit 110 marks the channel as faulty and automatically switches to another channel to continue communication. Simultaneously, the display unit 120 shows an alarm message "CAN channel X fault, switched to redundant channel" and records the fault timestamp for subsequent maintenance analysis. In one embodiment, the unit controller 130 is installed in a drawer-type functional compartment of the ship's main power distribution board using an embedded rail structure. The drawer-type functional compartment has corrugated heat dissipation fins on its side walls, which connect with the ventilation ducts of the main power distribution board to form a forced convection heat dissipation path. The display and control unit 120 is embedded in the cabinet door of the main distribution board 101 through a shock-absorbing bracket. The electromagnetic shielding layer of the rugged touch display of the display and control unit 120 is reliably connected to the metal cabinet of the main distribution board through an elastic conductive pad (such as a beryllium copper finger spring) to form a continuous electromagnetic shielding cavity, which effectively isolates the high-frequency electromagnetic interference generated by the opening and closing of the circuit breaker in the main distribution board.The circuit board of the generator set controller 130 is vertically mounted, with heat-generating components facing the heat sink fins. The circuit board surface is coated with a conformal coating (moisture-proof, salt spray-proof, and mildew-proof) to withstand the harsh environment of the ship's auxiliary engine room. The generator set controller 130 features thirty digital inputs, fourteen digital outputs, six 4-20mA analog inputs, four 4-20mA analog outputs, two sets of three-phase 0-100V voltage and current acquisition interfaces, and one 0-5A bus voltage acquisition interface. Its compact dimensions are 98mm (width) × 161mm (depth) × 308mm (height). It is used for comprehensive monitoring and control of generator sets (such as generator sets 1 to 4). This integrated layout lays the foundation for system deployment within the confined space of a ship. The system also integrates a shore power controller, a jumper controller, and a charging / discharging device. The shore power controller and jumper controller communicate with the core unit via redundant A / B channels on a dual CAN bus, forming a redundant network structure. The shore power controller is specifically designed to monitor and manage the shore power connection process. Upon receiving a shore power connection command, the controller sends shore power voltage, frequency, and phase sequence parameters to the power monitoring unit via channel A. If a communication interruption is detected on channel A (three consecutive no-response attempts), it automatically switches to channel B for data transmission. If both channels A and B fail (e.g., a short circuit in the bus physical layer), it immediately sends a prohibition signal to each generator controller 130 via hardwiring (e.g., a normally closed relay contact opening), forcibly blocking the main switch closing circuit to prevent asynchronous closing caused by parallel operation during communication failure. It monitors shore power voltage and frequency parameters in real time and exchanges data with the power monitoring unit 110 via dual CAN buses to achieve automatic opening and closing control of the shore power switch. When the ship docks, the shore power controller automatically switches to shore power supply mode according to the instructions of the power monitoring unit 110, disconnecting the ship's generator set, thereby reducing fuel consumption and emissions. The jumper controller controls the jumper switches to enable power connection during grid segmentation or faults. For example, when a busbar section fails, the jumper controller can quickly isolate the faulty area and transfer the load to a healthy busbar via the jumper switches, ensuring power continuity. The charging / discharging device typically includes a charging module, a discharging control circuit, and a battery status monitoring interface. It collects battery voltage, current, and charge parameters in real time and uploads the data to the power monitoring unit 110 via dual CAN buses for centralized monitoring and decision-making. For instance, during sudden increases in grid load or generator failures, the charging / discharging device can automatically switch to discharging mode to provide short-term backup power and prevent grid collapse; while during light grid loads, it switches to charging mode to optimize energy utilization.

[0026] like Figure 2 As shown, the system operation of the present invention begins with the automated start-up process of the generator set, including the following steps: Step S201: Check if the exhaust cover is open. If yes, proceed to step S202; if no, open the cover and check again.

[0027] Step S202: Determine whether the startup conditions are met. If yes, send a startup command and proceed to step 203; otherwise, proceed to step S209 to end the process.

[0028] Step S203: Determine if the unit has started successfully. If yes, proceed to step S204; if no, attempt a second start-up and determine success again. If the second start-up is successful, proceed to step S204; if still no, attempt a third start-up and determine success again. If the third start-up is successful, proceed to step S204; if still no, proceed to step S209 to end the process.

[0029] Step S204: Adjust the generator speed to ensure the generator set is running at an appropriate speed. After completion, proceed to step S205.

[0030] Step S205: Determine if the system has reached its rated power. If yes, proceed to step S206; otherwise, return to step 204 to continue speed adjustment.

[0031] Step S206: Determine if there is power in the grid. If yes, proceed to step S207 for parallel operation; otherwise, proceed to step S208 for power supply.

[0032] Step S207: The power grid is connected in parallel. The generator set is safely connected to the power grid. After completion, proceed to step S209.

[0033] Step S208: Power supply is initiated by closing the circuit breaker. In the absence of power in the grid, the circuit breaker is closed to start supplying power. After completion, proceed to step S209.

[0034] Step S209: The process ends. After all operations are completed, the automatic startup process ends.

[0035] The process includes checking the condition of the exhaust cover, determining the starting conditions, executing the starting command (if it fails, try up to three times), adjusting the unit speed to the rated power, and then deciding whether to close the circuit to supply power or switch to parallel operation based on whether there is an electrical signal from the power grid.

[0036] The power monitoring unit 110 receives operating parameters and grid parameters from each unit controller 130 via a dual CAN bus, performs centralized processing and display, and generates coordinated control commands for parallel operation control of the units based on the operating parameters and grid parameters. These commands are then sent to the corresponding unit controller 130 via the dual CAN bus. The core control functions of the system are quasi-synchronous paralleling and automatic power distribution. When a generator unit needs to be connected to the existing grid, the power monitoring unit 110 and the corresponding unit controller 130 work together. Based on the voltage difference, frequency difference, and phase difference between the grid and the generator unit being connected, which are collected in real time by the unit controller 130, the unit controller 130 controls the generator unit to automatically adjust its voltage and speed. When the voltage, frequency, and phase conditions meet the quasi-synchronous requirements, the main switch of the generator unit is closed to achieve quasi-synchronous paralleling. In response to a voltage difference that does not meet the requirements, the system automatically performs voltage regulation; in response to a negative frequency difference, it controls the generator set to be paralleled to accelerate; in response to a positive frequency difference that is greater than a preset frequency value (e.g., 0.3Hz), it controls the generator set to be paralleled to decelerate; after both the voltage and frequency differences meet the requirements, it performs phase condition judgment, and when the phase condition is met and the paralleling condition detection time is less than a preset time, it issues a paralleling closing command to achieve precise paralleling. During quasi-synchronous paralleling, the power monitoring unit 110 not only detects the real-time voltage difference, frequency difference, and phase difference, but also calculates the phase difference change rate dθ / dt based on the real-time measured frequency difference Δf, and predicts the phase overlap time point t0 within the next 3-5 seconds using a linear prediction algorithm. When the absolute value of the detected voltage difference is less than 5% of the rated voltage (i.e., ±18V for a 400V system) and the frequency difference is within the range of -0.1Hz to +0.3Hz, a closing preparation command is issued to the unit controller 130 200ms before the predicted phase reconciliation time t0. This ensures that the mechanical action delay of the main switch (approximately 100-150ms) matches the electrical preparation time, guaranteeing that closing is completed when the actual phase difference is less than 5° and the absolute value of the frequency difference is less than or equal to 0.1Hz, thus limiting the inrush current at the moment of paralleling to within 10% of the rated current. See also Figure 3 The automatic lane-keeping control process includes the following steps: Step S301: The process starts, the system is initialized, and preparations are made for parallel operation.

[0037] Step S302: Voltage difference detection, determining whether the voltage difference between the generator to be connected and the grid is within the allowable range. If yes, proceed to step S303; otherwise, automatically perform voltage regulation operation and return to step S302 for re-detection.

[0038] Step S303: Frequency difference detection, determine whether the frequency of the unit to be connected is less than the grid frequency (i.e., whether there is a negative frequency difference). If yes, proceed to step S304; if no, proceed to step S306.

[0039] Step S304: Accelerate the generator unit to be connected, adjust the frequency of the generator unit to be connected to be greater than the grid frequency, and then proceed to step S305.

[0040] Step S305: Frequency adjustment monitoring. Determine whether the frequency adjustment was completed within the specified time. If not, return to step S302 to continue monitoring; if yes, issue a frequency adjustment abnormality alarm and end the process.

[0041] Step S306: Positive frequency difference detection, determine if the frequency difference is less than 0.1Hz. If yes, proceed to step 304 for acceleration adjustment; if no, proceed to step S307.

[0042] Step S307: Large frequency difference detection, determine if the frequency difference is greater than 0.3Hz. If yes, proceed to step 308 for deceleration adjustment; if no, proceed to step S309.

[0043] Step S308: The generator to be connected slows down, the frequency of the generator to be connected is adjusted to be close to the grid frequency, and then the process returns to step S305 for monitoring.

[0044] Step S309: Close timing determination. Determine if the parallel operation condition detection time is less than 60 seconds. If yes, proceed to step S310; otherwise, send a parallel operation closing command and proceed to step S311.

[0045] Step S310, Parallelization failure handling: If parallelization fails after the parallelization closing command is issued, a parallelization failure alarm is issued.

[0046] Step S311: Determine the closing result. Determine whether the closing operation was successful. If yes, proceed to step S312; otherwise, return to step S310 to handle the paralleling failure.

[0047] Step S312, process ends, automatic vehicle paralleling process completed.

[0048] During parallel operation of multiple generator sets, the power monitoring unit 110 calculates the power distribution difference based on the active / reactive power of each unit acquired via dual CAN buses, and generates load adjustment commands. These commands are then used by the corresponding unit controllers to control the deceleration and voltage increase of high-power units and / or the acceleration and voltage decrease of low-power units, thereby achieving automatic balanced distribution of active / reactive power among the parallel units. This effectively solves the problems of low paralleling success rate and uneven power distribution caused by insufficient coordination control precision during multi-unit parallel operation, improving the system's automation level and operational stability. Before generating load adjustment commands, the power monitoring unit 110 establishes a power-speed characteristic curve P=f(n) based on historical operating data of each unit (such as the operating records of the previous 100 hours) and divides the system into efficiency ranges (high-efficiency range: 85%-100% rated power, low-efficiency range: 30%-50% rated power). When power distribution adjustment is required, units in the low-efficiency range are prioritized for power increase / decrease adjustments to improve overall fuel efficiency. Meanwhile, the system presets vibration speed restriction zones as 45%-55% (corresponding to the low-frequency vibration zone) and 85%-95% (corresponding to the high-frequency critical speed zone) of the rated speed. When generating speed regulation commands, it avoids these zones by querying the speed restriction zone table. If the calculated target speed falls into the restriction zone, it automatically adjusts to the restriction zone boundary value (such as 44% or 96% of the rated speed) and prompts "Vibration speed restriction zone has been avoided" through the display and control unit 120. When the grid frequency is within the required range but the power distribution difference between generating units exceeds the required range, the higher-power generating units are controlled to decelerate while the lower-power generating units are controlled to accelerate. When the grid frequency is below the first frequency threshold (e.g., 49.75Hz), if the reactive power distribution difference between generating units is within the allowable range, all parallel generating units are controlled to accelerate simultaneously; if it exceeds the allowable range, the lower-power generating units are controlled to accelerate. When the grid frequency is above the second frequency threshold (e.g., 50.25Hz), if the reactive power distribution difference between generating units is within the allowable range, all parallel generating units are controlled to decelerate simultaneously; if it exceeds the allowable range, the higher-power generating units are controlled to decelerate. This achieves the dual objectives of grid frequency stability and reasonable power distribution. See also Figure 4 The multi-unit frequency regulation control process includes the following steps: Step S401: The system checks whether it is running in standalone mode. If so, it executes the standalone frequency stabilization program; otherwise, it proceeds to step 402. Step S402: Determine whether the power grid frequency is within the range. If yes, proceed to step S403; otherwise, proceed to step S404. Step S403: Determine whether the power distribution difference of the unit is within the required range. If yes, return to step S402; otherwise, proceed to step S405. Step S404: Determine if the frequency is less than 49.75Hz. If yes, proceed to step S406; otherwise, proceed to step S407. In step S405, the high-power unit decelerates and the low-power unit accelerates, then returns to step S402; Step S406: Determine whether the difference in active power distribution between the units is within the allowable range. If so, the units accelerate simultaneously; otherwise, the unit with lower power accelerates, and then return to step S402. Step S407: Determine whether the difference in active power distribution between the units is within the allowable range. If so, the units decelerate simultaneously; otherwise, the units with higher power decelerate, and then return to step S402.

[0049] When operating as a single unit, the system performs single-unit frequency regulation control. If the grid frequency is detected to be lower than the first frequency threshold (e.g., 49.75Hz), the system controls the online operating unit to accelerate; if the grid frequency is detected to be higher than the second frequency threshold (e.g., 50.25Hz), the system controls the online operating unit to decelerate. See also... Figure 5 The single-unit frequency regulation control process includes the following steps: Step S501: Determine whether it is running on a standalone machine. If yes, proceed to step S502; otherwise, repeat step S501. Step S502: Determine whether the power grid frequency is within the required range. If yes, return to step S501; otherwise, proceed to step S503. Step S503: Determine if the frequency is less than 49.75Hz. If so, accelerate the on-grid unit and return to step S502; otherwise, proceed to step S504. Step S504: Determine if the frequency is greater than 50.25Hz. If so, decelerate the on-grid unit and return to step S502; otherwise, no action is taken.

[0050] The distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system of this embodiment collects the operating parameters of each generator set and the power grid in real time through the unit controller 130, and realizes real-time sharing and interaction of the entire system operation data between control units with the help of a highly reliable dual CAN bus, providing a data foundation for centralized collaborative decision-making. On this basis, the power monitoring unit 110 performs unified calculations based on global data and generates collaborative control commands. During the paralleling process, the voltage, frequency and phase difference between the power grid and the generator set to be paralleled are compared in real time, and the generator set to be paralleled is controlled in a closed loop to automatically adjust the voltage and speed until the quasi-synchronous conditions are met and then the circuit is closed. This process eliminates the dependence on independent dedicated synchronization devices and realizes fast and accurate automatic quasi-synchronous paralleling. During parallel operation, the power monitoring unit 110 continuously calculates the distribution difference of active and reactive power among the generating units. It then uses commands to drive the unit controllers to decelerate and boost voltage for high-power units and accelerate and depress voltage for low-power units, forming a closed-loop control. This achieves automatic, stable, and balanced distribution of active and reactive power among the parallel generating units under dynamic load changes, effectively suppressing power oscillations and frequency fluctuations. The high degree of automation in the entire parallel operation and power distribution process reduces reliance on manual operation, lowers the operational complexity and instability risks caused by human factors, and thus improves the overall control accuracy, automation level, and system stability during multi-generator parallel operation.

[0051] like Figure 6As shown, in one embodiment, the system of the present invention performs automatic generator set disconnection and shutdown control, specifically including: when a generator set is running alone and a general fault occurs, a standby generator set is started, an automatic paralleling procedure is executed, and the faulty generator set is disconnected after successful paralleling; when a generator set is running in parallel and its power is less than a preset value and a delay time is reached, the generator set to be disconnected is controlled to decelerate, and the generator set remaining on the grid is controlled to accelerate; when the power of the generator set is less than the disconnection preset value, a trip command is issued and a shutdown command is issued after a delay; when a generator set experiences a serious fault, a shutdown command for the generator set is issued directly, thus realizing the automatic and safe disconnection of the faulty generator set. When the power monitoring unit 110 detects a general fault (such as non-fatal faults like high cooling water temperature or low lubricating oil pressure) in a single-unit operating system, it immediately activates the dynamic priority arbitration algorithm: it suspends response to heavy load inquiry signals from the main power control system, prioritizes starting the standby unit, executes the automatic paralleling procedure, and after successful paralleling, controls the faulty unit to decelerate and the grid-connected unit to accelerate. When the active power of the faulty unit drops below 5% of its rated power, it issues a trip command, followed by a shutdown command after a 30-second delay. If a serious fault occurs (such as main switch tripping or reverse power protection activation), it immediately broadcasts a fault code (e.g., 0xFF01 indicating a serious fault) via the dual CAN bus, triggering the LED indicator of the physical control button 122 on the display and control unit 120 to flash red at a frequency of 1Hz, and the display and control unit buzzer to sound intermittently at the same frequency, prompting operators to pay immediate attention. The automatic disconnection and shutdown control process includes the following steps: Step S601: The system starts running; proceed to step S602. Step S602: Determine whether the units are operating in parallel. If yes, proceed to step S603; otherwise, proceed to step S604. Step S603: Determine whether the unit is operating normally. If yes, proceed to step S605; otherwise, proceed to step S606. Step S604: Determine whether the unit is operating normally (each individual unit is operating). If yes, return to step S602; otherwise, proceed to step S607. Step S605: Determine whether the unit power is less than the preset value. If yes, proceed to step S608; otherwise, return to step S602. Step S606: Determine if the unit is experiencing a general fault. If so, disconnect the faulty unit; otherwise, proceed to step S610. Step S607: Determine if the unit has a general fault. If yes, proceed to step S610; otherwise, proceed to step S614. Step S608: Determine whether the delay time has been reached. If yes, proceed to S611; otherwise, return to step S605. Step S609: Start the standby unit, automatically connect it to the main unit, disconnect the faulty unit, and then proceed to step S611; Step S610: Determine that the unit has a serious malfunction, proceed to step S614; Step S611: The generator set to be disconnected decelerates, the generator set remaining on the grid accelerates, and then proceeds to step S612; Step S612: Determine whether the unit power is less than the preset value for disconnection. If yes, proceed to step S613; otherwise, return to step S611. Step S613: Issue a disconnection command for the unit, delay for a period of time, and then proceed to step S614; Step S614: Issue a unit shutdown command.

[0052] like Figure 7 As shown, in one embodiment, the system of the present invention performs overload inquiry control, specifically including: receiving an overload inquiry signal and calculating the remaining active power of the power grid; if the remaining active power meets the overload start-up conditions, then overload start-up is allowed; if the remaining active power does not meet the overload start-up conditions and there are still standby units not in operation, then a generator addition prompt is issued and the automatic paralleling procedure and automatic frequency regulation and load adjustment procedure are started sequentially; if the remaining active power does not meet the overload start-up conditions and no standby units are available, then overload start-up is rejected after a delay and an alarm is issued. By calculating the remaining active power of the power grid to determine whether the overload start-up conditions are met, if they are met, start-up is allowed; if they are not met and there are standby units, a generator addition prompt is issued and the automatic paralleling and frequency regulation and load adjustment procedures are started; if there are no standby units, start-up is rejected and an alarm is issued, thus avoiding power grid instability caused by the sudden addition of high-power loads. In the overload inquiry control, the power monitoring unit 110 receives the overload inquiry signal from the active power control system or integrated control console via Ethernet using the Modbus TCP / IP protocol, and calculates the remaining active power of the power grid. ,in, The sum of the rated power of all online operating generator sets. This represents the current actual total active power of the power grid. The preset power reserve margin is typically set as follows: That is, 20% of the rated power of the largest single unit. If Meets the heavy-load start-up conditions ( ,in If the power requirement of the requested heavy-load equipment is not met, startup is allowed; if not, and a standby unit is available, a power increase prompt is issued and the automatic paralleling procedure is initiated. During this period, the execution of any unit's disconnection and shutdown command is suspended through a dynamic priority arbitration algorithm to prevent units from mistakenly joining the grid due to load fluctuations during the power increase process; if no standby unit is available, a rejection signal (frame ID 0x300, data byte 0x00) is sent via the dual CAN bus after a 30-second delay, and an audible and visual alarm is triggered. The heavy-load inquiry control process includes the following steps: Step S701: Reload the query signal, calculate the remaining power of the power grid, and then proceed to step S702; Step S702: Determine whether the overload start condition is met. If yes, proceed to step S703; otherwise, proceed to step S704. Step S703: Allow reload startup, then proceed to step S707; Step S704: Determine if the unit is used up. If yes, proceed to step S705; otherwise, proceed to step S706. Step S705: Delay, then refuse reload startup and alarm, then proceed to step S707; Step S706: Automatically start the program, start the automatic paralleling program and the automatic frequency regulation and load adjustment program, and then return to step S701; Step S707: End the process.

[0053] The power monitoring unit 110 runs on a computer and is equipped with a control panel. The computer is ruggedized and features a fanless cooling design. It is installed in an independent control compartment of the main power distribution board 101. Its human-machine interface includes: a single-line schematic diagram interface, which graphically displays the single-line diagram of the main distribution board and marks the communication status of the dual CAN bus A / B channels in real time (green indicates normal, red indicates fault) and the number of redundancy switching; a unit priority standby order setting interface, which allows operators to adjust the unit priority by dragging and dropping on the ruggedized touch display 121 (e.g., setting Unit #1 as the first standby and Unit #2 as the second standby), and automatically lowering the priority of the unit to the lowest when a unit fault is detected; a unit status monitoring interface, which displays the embedding position temperature of each unit controller 130 in real time (collected by the built-in temperature sensor), electromagnetic shielding status (determined by detecting the grounding resistance of the shielding layer), and communication error rate (statistical analysis of the CRC error rate of the most recent 1000 frames); and a power grid monitoring information interface, which displays the real-time adjustment of the frequency-power dual closed-loop coupling control strategy (e.g., the governor PWM duty cycle change curve) in the form of a trend graph. It communicates with external devices such as the main power control system and the integrated control console via Ethernet, and the dual CAN bus adopts a redundant design to ensure communication reliability. The power monitoring unit 110 is also configured to communicate with the ship's main power control system and integrated bridge via Ethernet to receive heavy load inquiry signals and provide feedback on the power grid status.

[0054] This invention has the following characteristics: Compact Integrated Design: Traditional marine electrical control systems typically use separate control cabinets, occupying a large space and unsuitable for small vessels. This invention employs an embedded design, directly integrating the electrical control system into the ship's switchboard, saving space and improving the overall integrity and compatibility of the equipment, making it particularly suitable for small vessels with limited space.

[0055] Intelligent paralleling technology: Most existing systems rely on independent synchronizers (parallelizing devices) to complete paralleling operations. This invention achieves precise paralleling through communication and coordination between controllers, combined with real-time acquisition and calculation of the phase voltage of the power grid and generator by the controller to be paralleled. This distributed paralleling strategy not only reduces the dependence on independent synchronizers but also improves paralleling efficiency and reliability, making it particularly suitable for the compact layout of switchboards on small ships.

[0056] Efficient Fault Handling and Redundancy Design: This invention features automatic fault detection and handling capabilities, enabling rapid switching to backup units and load transfer in the event of a fault. Simultaneously, the system employs a redundancy design, with critical equipment such as controllers and communication links equipped with redundant backups, ensuring normal operation even in the event of a single point of failure, significantly improving system reliability and fault tolerance.

[0057] Modular and lightweight design: The system hardware adopts a modular design, facilitating installation, maintenance, and upgrades. Addressing the stringent weight and volume requirements of ships, this invention incorporates a lightweight design, reducing the weight and size of the equipment and further enhancing the system's applicability and economy.

[0058] Advanced control algorithms and intelligent strategies: This invention employs advanced control algorithms, such as automatic paralleling, frequency regulation and load adjustment, and heavy load inquiry, to ensure stable operation even under complex conditions. Through real-time data interaction and intelligent control strategies, the system can optimize the power grid's operating status and improve the overall performance and reliability of the power system.

[0059] The aforementioned distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system, by embedding the unit controller in the drawer-type functional compartment of the ship's main switchboard and embedding the display and control unit inside the main switchboard cabinet door, and using conductive pads to form a continuous shield between the electromagnetic shielding layer of the ruggedized touch display and the metal cabinet of the main switchboard, constructs a highly electromagnetically compatible distributed monitoring architecture in the ship's strong electromagnetic interference environment. This significantly improves the system's anti-interference capability and reliability in the confined engine room space. Through the physical isolation A / B redundant channels of the dual CAN bus and the bit-by-bit comparison algorithm, redundant backup and automatic fault switching of data communication are realized. When three consecutive CRC check errors are detected, the channel is automatically switched and an alarm is triggered, ensuring the continuity and integrity of the transmission of critical control commands. At the control strategy level, through a preset dynamic priority arbitration algorithm, when the heavy load inquiry signal and the fault disconnection request signal occur concurrently, the load transfer of the faulty unit is prioritized and the heavy load start sequence is suspended. During the heavy load increase process, the disconnection shutdown command is suspended, realizing intelligent conflict arbitration of fault handling and load management, which significantly improves the fault response safety and power supply continuity of the ship power station. During the paralleling process, the phase difference change rate is calculated based on the real-time measured frequency difference, the phase overlap time point in the next 3-5 seconds is predicted, and the closing preparation command is issued 200ms in advance, realizing accurate phase prediction and advance compensation. Combined with the fine threshold control of voltage difference ±5% and frequency difference -0.1Hz / +0.3Hz, the paralleling closing phase difference is controlled within 5°, which greatly reduces the paralleling inrush current. During parallel operation, a frequency-power dual closed-loop coupling control strategy is adopted. When the grid frequency is lower than the first frequency threshold (49.75Hz), the low-power unit is prioritized to accelerate at 1.5 times the speed. When the frequency is higher than the second frequency threshold (50.25Hz), the high-power unit is prioritized to decelerate. Power balance is achieved while maintaining the grid frequency stable within the range of 50±0.25Hz. By establishing the power-speed characteristic curve based on the historical operating data of each unit, the unit in the inefficient range is prioritized to be adjusted and the vibration speed forbidden zones of 45%-55% and 85%-95% are avoided, thus achieving dual optimization of energy-saving operation and mechanical protection. Furthermore, a robust computer-interface interface displays real-time communication status of the dual CAN bus A / B channels, redundancy switching counts, mounting location temperature, electromagnetic shielding status, and communication error rate. A multi-layered safety assurance system is also constructed through hard-wiring emergency stop signals and Ethernet control commands with priority settings (hard-wiring priority is higher than Ethernet Modbus TCP / IP commands). Through coordinated optimization of structure, algorithm, and communication, the entire system significantly enhances the adaptive and fault-tolerant capabilities of the ship's power system under complex operating conditions, while improving the control accuracy, automation level, and stability of multi-generator parallel operation.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A distributed monitoring embedded quasi-synchronous parallel low-voltage AC power control system, characterized in that, The system includes a power monitoring unit, at least two display and control units, and multiple generator controllers corresponding to multiple generator sets respectively; The power monitoring unit, the display and control unit, and the generator set controller are connected via a dual CAN bus. The dual CAN bus uses physically isolated A / B redundant channels. The generator set controller is embedded in a drawer-type functional compartment of the ship's main power distribution board. The display and control unit is embedded inside the cabinet door of the main power distribution board. The display and control unit includes a ruggedized touch display and physical control buttons. The electromagnetic shielding layer of the ruggedized touch display and the metal cabinet of the main power distribution board form a continuous shield through conductive pads. The generator unit controller is used to collect the operating parameters and grid parameters of the corresponding generator unit in real time. The operating parameters include generator speed, active power, reactive power, power factor, and winding temperature. The grid parameters include grid voltage, current, frequency, and phase. The controller transmits the operating parameters and grid parameters to the power monitoring unit and other generator unit controllers through the A / B dual-channel redundancy of the dual CAN bus. The controller is also used to receive control commands from the power monitoring unit or display and control unit. The control commands include speed regulation pulse width modulation signals, voltage regulation duty cycle signals, and main switch opening and closing trigger signals. The controller then performs start-up, speed regulation, and main switch opening and closing control on the corresponding generator unit. The power monitoring unit is used to receive operating parameters and grid parameters from each unit controller via the dual CAN bus, centrally process the operating parameters based on a preset dynamic priority arbitration algorithm, generate collaborative control commands for unit parallel operation control, and send them to the corresponding unit controllers via the dual CAN bus. The dynamic priority arbitration algorithm includes: when a reload inquiry signal and a fault disconnection request signal are received concurrently, the load transfer of the faulty unit is executed first, and the reload start sequence is suspended. When a generator set to be connected to an existing power grid needs to be connected, the power monitoring unit and the corresponding generator controller work together. Based on the voltage difference, frequency difference, and phase difference between the power grid and the generator set to be connected, which are collected in real time by the generator controller, the generator controller controls the generator set to be connected to perform automatic voltage and speed regulation. The automatic voltage and speed regulation includes: automatically performing voltage regulation operation in response to the voltage difference not meeting the requirements; controlling the generator set to be connected to accelerate in response to the frequency difference being negative; controlling the generator set to be connected to decelerate in response to the frequency difference being positive and greater than a preset frequency value; and after both the voltage difference and frequency difference meet the requirements, performing phase condition judgment, and issuing a connection closing command when the phase condition is met and the connection condition detection time is less than a preset time, to achieve quasi-synchronous connection. During the parallel operation of multiple generator sets, the power monitoring unit calculates the power distribution difference based on the active / reactive power of each unit acquired through the dual CAN bus, and generates a load adjustment command. The generation of the load adjustment command follows a frequency-power dual closed-loop coupling control strategy: when the grid frequency is within the required range but the power distribution difference of the units exceeds the required range, the units with higher power are controlled to decelerate while the units with lower power are controlled to accelerate; when the grid frequency is lower than the first frequency threshold, if the active / reactive power distribution difference of the units is within the allowable range, all parallel units are controlled to accelerate simultaneously; if it exceeds the allowable range, the units with lower power are controlled to accelerate first; when the grid frequency is higher than the second frequency threshold, if the active / reactive power distribution difference of the units is within the allowable range, all parallel units are controlled to decelerate simultaneously; if it exceeds the allowable range, the units with higher power are controlled to decelerate first, so as to achieve automatic balanced distribution of active / reactive power among the parallel units and maintain the grid frequency stable within the range of 50±0.25Hz during the load adjustment process.

2. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The system also includes a shore power controller and a jumper controller. The shore power controller and the jumper controller are connected to the power monitoring unit via A / B dual-channel redundant communication of the dual CAN bus. The shore power controller is configured to: send shore power parameters to the power monitoring unit through channel A when it receives a shore power input command; automatically switch to channel B when channel A fails; and send a prohibition signal to the unit controller through hardwiring when both channels fail.

3. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The method of controlling the generator set to be paralleled for automatic voltage and speed regulation based on the voltage difference, frequency difference, and phase difference between the power grid and the generator set to be paralleled, which are collected in real time by the generator set controller, includes: In response to the absolute value of the voltage difference being greater than a preset voltage threshold, the unit controller outputs a voltage regulation duty cycle signal to the automatic voltage regulator to perform automatic voltage regulation. The preset voltage threshold is ±5% of the rated voltage. In response to a frequency difference that is negative and less than -0.1Hz, a speed regulation pulse width modulation signal is output to the electronic speed governor to control the acceleration of the generator set to be paralleled; In response to a frequency difference that is positive and greater than +0.3Hz, the generator set to be paralleled is controlled to decelerate; After both the voltage difference and frequency difference meet the requirements, the phase difference change rate is calculated based on the real-time measured frequency difference to predict the phase overlap time point within the next 3-5 seconds. A closing preparation command is issued 200ms before the phase overlap time point, and a parallel closing command is issued when the actual phase difference is detected to be less than 5° and the absolute value of the frequency difference is less than or equal to 0.1Hz.

4. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The system is used to perform automatic generator set disconnection and shutdown control, and works in conjunction with the dynamic priority arbitration algorithm, specifically including: If a general fault occurs in a unit during stand-alone operation, the power monitoring unit will pause responding to any heavy load inquiry signals, prioritize starting the standby unit, execute the automatic paralleling procedure, and after successful paralleling, control the faulty unit to decelerate and control the stationary unit to accelerate through the unit controller. When the active power of the faulty unit is less than the preset value for disconnection, it will issue a trip command and issue a shutdown command after a delay. When operating in parallel, if the active power of a certain unit is less than 20% of the rated power and the delay time is reached, the unit is determined to be a unit to be disconnected. The unit to be disconnected is controlled to decelerate, and the units remaining on the grid are controlled to accelerate. When the active power of the unit is less than 5% of the rated power, its tripping command is issued and a shutdown command is issued after a delay. When a serious malfunction occurs in the unit, a shutdown command is directly issued for the unit, and a fault code is broadcast through the dual CAN bus. This triggers the LED indicator of the physical control button of the display and control unit to flash red as an alarm, and also triggers the audible alarm of the display and control unit.

5. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The system is also used to perform overloaded query control and is linked with the dynamic priority arbitration algorithm, specifically including: Receive heavy load inquiry signals from the ship's active power control system or integrated bridge and calculate the power grid's remaining active power. The calculation includes the sum of the rated power of the currently operating units minus the actual load power and then minus the power reserve margin. If the remaining active power meets the heavy load start-up conditions, a start-up permission signal is sent to the load controller via the dual CAN bus. If the remaining active power does not meet the heavy load start-up conditions and there are still standby units that are not in operation, an additional unit prompt will be issued and the automatic paralleling procedure and automatic frequency regulation and load adjustment procedure will be started in sequence. During the additional unit process, the execution of any unit disconnection and shutdown command will be suspended. If the remaining active power does not meet the heavy load start-up conditions and no backup unit is available, a heavy load start-up rejection signal will be sent through the dual CAN bus after a 30-second delay, and an audible and visual alarm will be issued. At the same time, the grid status will be fed back to the active power control system.

6. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The power monitoring unit runs on a ruggedized computer and provides a human-machine interface, which includes: The single-line schematic interface displays the A / B channel communication status and redundancy switching count of the dual CAN bus in real time. The unit priority standby order setting interface allows operators to set the unit priority through the ruggedized touch display, and automatically adjusts the priority when a unit failure is detected. The unit status monitoring interface displays the installation location temperature, electromagnetic shielding status, and communication error rate of each unit controller. The power grid monitoring information interface displays the real-time adjustment amount of the frequency-power dual closed-loop coupling control strategy; The network status monitoring interface displays the status and heartbeat signals of the dual CAN bus nodes of the power monitoring unit, display and control unit, and unit controller.

7. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The power monitoring unit is also configured to communicate with the ship's main power control system and integrated bridge via Ethernet to receive heavy load inquiry signals and feedback the power grid status using the Modbus TCP / IP protocol. At the same time, it receives hard-wired emergency stop signals from the display and control unit via the dual CAN bus. The hard-wired emergency stop signals have a higher priority than the Ethernet control commands.

8. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The system is also used to perform single-unit frequency regulation control. When the power grid is running as a single unit, the power monitoring unit switches to single-unit frequency stabilization mode. If the power grid frequency is detected to be lower than the first frequency threshold, the online operating unit is controlled to accelerate. If the power grid frequency is detected to be higher than the second frequency threshold, the online operating unit is controlled to decelerate.

9. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The dual-CAN bus A / B dual-channel redundant communication includes: when the unit controller sends data, it simultaneously sends data frames with the same frame ID to both channel A and channel B; the power monitoring unit simultaneously receives data from both channel A and channel B and judges data consistency through a bit-by-bit comparison algorithm; when a certain channel is detected to have CRC check errors or data inconsistency for 3 consecutive times, the channel is marked as a faulty channel and switched to another channel; at the same time, the display and control unit displays a channel fault alarm.

10. The low-voltage AC power control system with distributed monitoring and embedded quasi-synchronous parallel operation according to claim 1, characterized in that, The generation of the coordinated control commands also includes: The power monitoring unit establishes a power-speed characteristic curve based on the historical operating data of each unit. Before generating the load adjustment command, it first queries the characteristic curve to determine the current efficiency range of each unit, prioritizes adjusting the units in the low efficiency range, and avoids the vibration speed restriction range of each unit. The vibration speed restriction range is 45%-55% and 85%-95% of the rated speed.

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