A power supply and distribution system for an ROV

Abstract

The application discloses a power supply and distribution system for an ROV, and relates to the technical field of underwater equipment power systems.The system comprises a medium-voltage medium-frequency power supply, an umbilical cable, a medium-frequency transformer, a rectifier module and a control panel.The medium-voltage medium-frequency power supply converts low-voltage power-frequency alternating current into medium-voltage medium-frequency alternating current, which is transmitted to the medium-frequency transformer through the umbilical cable.The medium-frequency transformer is rectified into DC bus voltage by the rectifier module after voltage reduction.The control panel collects the bus voltage and load current at the ROV end and feeds back the bus voltage and load current to the surface medium-voltage medium-frequency power supply.The medium-voltage medium-frequency power supply performs online identification on equivalent parameters of a power supply link, calculates multiple compensation components, and adaptively adjusts the weight according to the operating state, and combines PID control to adjust the output voltage.The system can reduce long-distance transmission loss, and is beneficial to improving the voltage stability and power supply reliability at the end of the ROV.

Description

Technical Field

[0001] This invention relates to the field of underwater equipment power system technology, and in particular to a power supply and distribution system for ROVs. Background Technology

[0002] ROVs (Remotely Operated Vehicles) are key examples of underwater unmanned equipment, capable of performing underwater exploration and surveillance tasks in various environments, even high-risk sea areas. The power supply system is the core of the ROV, directly determining its endurance, operating depth, and equipment safety. Without a stable power supply, the propulsion, exploration, and operational modules will all fail.

[0003] The ROV power supply and distribution system first needs to transmit electrical energy from the surface mother ship over long distances with high power and low loss in complex underwater environments to the ROV. Then, the ROV's own power supply unit converts the received electrical energy into the required electrical power and distributes it to various loads. As ROVs develop towards lightweight and fully electric designs, they are sensitive to equipment size and weight, requiring the underwater power supply to be minimized in size and weight while ensuring power supply reliability.

[0004] The existing power supply methods have the following shortcomings: If low-voltage DC is used to supply power from the surface to the underwater, the umbilical cable must use a very thick conductor to reduce cable loss, which is costly and has high cable resistance, thus reducing the maneuverability of the ROV; if low-voltage AC transmission is used and converted to DC underwater, the cable loss is relatively high; if high-voltage DC is used, it is difficult to reduce the DC voltage over a wide range underwater; if high-voltage low-frequency AC transmission is used, the transformer is large, which is not conducive to lightweight design.

[0005] Furthermore, during long-distance power supply to ROVs, changes in umbilical cable length, temperature, and laying conditions, as well as load disturbances, cause dynamic changes in the equivalent impedance of the power supply link, leading to voltage fluctuations at the end and reducing power supply stability and power quality. Existing solutions typically employ DC-DC converters for passive voltage regulation underwater, which is difficult to adapt to rapid changes in link parameters and increases the size and complexity of underwater equipment. Summary of the Invention

[0006] To address the aforementioned problems and technical requirements, the inventors have proposed a power supply and distribution system for ROVs. This system reduces cable losses, increases the local power density of ROVs, and features a simple and reliable structure. The technical solution of this invention is as follows: A power supply and distribution system for ROVs includes a medium-voltage intermediate-frequency power supply, an umbilical cable, and an intermediate-frequency transformer, a rectifier module, and a control board located at the ROV end. The intermediate-frequency transformer and rectifier module are housed in a power supply wet compartment, while the control board is located in a power supply control compartment. Power and signal transmission are achieved between the power supply wet compartment and the power supply control compartment via a watertight connector. The input of the medium-voltage intermediate-frequency power supply is connected to the ship's electrical system, and its output is connected to the primary side of the intermediate-frequency transformer via the umbilical cable. The secondary side of the intermediate-frequency transformer is connected to the input of the rectifier module, and the output of the rectifier module forms a DC bus for use by the ROV load. The control board is used to collect the DC bus voltage and load current and feed them back to the medium-voltage intermediate-frequency power supply.

[0007] The medium-voltage intermediate frequency power supply is equipped with a closed-loop voltage regulator. The closed-loop voltage regulator is configured to: predict the ROV terminal voltage and load current change trend in the next cycle based on the current feedback data; combine the effective value of the three-phase output line voltage collected locally; calculate the feedback error compensation component, voltage trend compensation component, link change compensation component, and load disturbance compensation component respectively; adaptively adjust the weight of each compensation component and sum them to generate a corrected voltage reference value for the ROV terminal DC bus; and adjust the output voltage of the medium-voltage intermediate frequency power supply through PID control based on the deviation between the corrected voltage reference value and the measured bus voltage.

[0008] A further technical solution is that the system may also include a hydraulic compensator. The power supply wet chamber is filled with transformer oil. The hydraulic compensator is connected to the power supply wet chamber through an oil pipe and is used to regulate the internal pressure of the power supply wet chamber to balance the pressure inside and outside the chamber, thereby reducing the thickness of the power supply casing and reducing its volume and weight.

[0009] A further technical solution involves the system further including a DC / DC module and an AC / DC circuit board, both housed within the power control compartment. The input of the DC / DC module is connected to the DC bus via a watertight connector, and the output provides low-voltage DC power to supply power to the low-voltage load at the ROV end.

[0010] The input terminal of the AC / DC circuit board is connected to the intermediate frequency AC power output from the intermediate frequency transformer via a watertight connector, and the output terminal is electrically connected to the control board to rectify and convert the intermediate frequency AC power into low-voltage DC power to power the control board.

[0011] The further technical solution is that, based on the current feedback data, the method for predicting the ROV terminal voltage and load current change trends in the next cycle is the same. The method for predicting the ROV terminal voltage trend in the next cycle includes: The first-order voltage change in the current period is calculated sequentially based on the DC bus voltage measured in adjacent sampling periods. and second-order voltage change ; The predicted value of the ROV terminal voltage trend for the next cycle is obtained by using discrete trend extrapolation. Represented as:

[0012] in, This is the DC bus voltage at the ROV terminal measured during the current sampling period.

[0013] A further technical solution involves calculating the feedback error compensation component and the voltage trend compensation component, including: The difference between the reference voltage value and the measured voltage value of the DC bus at the ROV end is calculated to obtain the feedback error compensation component. ; The difference between the DC bus voltage at the ROV terminal measured in the current sampling period and the predicted value of the ROV terminal voltage trend in the next period is calculated to obtain the voltage trend compensation component. .

[0014] Its further technical solution is to calculate the link change compensation component, including: Constructing a discrete parameter model of the system power supply link And perform online identification to obtain the updated model parameters for the next cycle. ; Updated values ​​based on identified parameters And the predicted value of the ROV terminal load current in the next cycle Calculate the predicted comprehensive voltage drop of the power supply link for the next cycle. , is represented as:

[0015] Calculate the difference between the predicted comprehensive voltage drop of the power supply link in the next cycle and the current cycle to obtain the link variation compensation component. ; in, This is the equivalent resistance of the umbilical cable conductor resistance and the circuit contact resistance. The equivalent inductance is formed by the distributed inductance of the umbilical cable, the leakage inductance of the intermediate frequency transformer, and the inductance of the filter circuit. This is the inherent voltage drop bias of the intermediate frequency transformer and rectifier module; This refers to the ROV terminal load current measured during the current sampling period. This is the duration of the sampling period.

[0016] A further technical solution involves online identification of the discrete parameter model to obtain the updated model parameters for the next period. ,include: RMS value of three-phase output line voltage based on synchronous sampling and ROV terminal DC bus voltage Calculate the observed values ​​of the overall voltage drop of the power supply link. And use discrete parameter models to predict the overall pressure drop. ,in Represented as:

[0017] Calculate the overall pressure drop observation value Compared with the predicted value The identification error between The model parameters are iteratively updated using an online update method with normalization terms and physical boundary projections, as shown below:

[0018] in, For AC-DC equivalent conversion factors; Update the gain matrix for pre-defined diagonal positive definite parameters; , The change in load current measured in adjacent sampling periods; To prevent positive numbers with a denominator of zero; This is the physical boundary projection operator.

[0019] A further technical solution involves calculating the load disturbance compensation component, including: The first-order current change in the current period is calculated sequentially based on the load current measured in adjacent sampling periods. and second-order current change ; Estimate the voltage compensation component corresponding to the load disturbance based on the first and second order changes of the load current. , is represented as:

[0020] in, and This is the current-voltage disturbance conversion factor.

[0021] A further technical solution involves adaptively adjusting the weights of each compensation component, including: Calculate the moving root mean square of each compensation component. The state significance is obtained based on the ratio of the absolute value of the compensation component to the corresponding moving average root. , is represented as:

[0022] Combine the benchmark weights of each compensation component and state sensitivity coefficient Calculate unnormalized weights , is represented as:

[0023] For unnormalized weights Perform normalization so that the sum of all weights is 1; in, These correspond to the feedback error compensation component, voltage trend compensation component, link change compensation component, and load disturbance compensation component, respectively. To prevent positive numbers with a denominator of zero.

[0024] Its further technical solution is to normalize the weights. With corresponding compensation components Weighted summation is used to generate the corrected voltage reference value for the DC bus at the ROV end. , is represented as:

[0025] in, The initial voltage reference value for the DC bus at the ROV end; and To correct the upper and lower limits of the voltage reference value; This represents the amplitude limiting function.

[0026] The beneficial technical effects of this invention are: First, this application uses a medium-voltage intermediate frequency power supply to convert low-voltage power frequency into medium-voltage intermediate frequency power for long-distance transmission. Increasing the transmission voltage helps reduce cable transmission loss, and increasing the transmission frequency helps reduce the size of the underwater intermediate frequency transformer, thereby increasing the power density of the underwater power supply.

[0027] Secondly, this application collects the ROV end bus voltage, load current, etc., through the control board and feeds them back to the medium-voltage intermediate frequency power supply on the water surface. The closed-loop voltage regulator identifies the equivalent parameters of the power supply link online, which can track the changes in link impedance caused by changes in umbilical cable length, temperature and laying status in real time, which is beneficial to improving the stability of the voltage at the end of the long-distance power supply system.

[0028] Third, this application calculates four compensation components—feedback error, voltage trend, link change, and load disturbance—and adaptively adjusts the weight of each component, enabling the system to reasonably allocate the effects of each control factor under different operating conditions, which is beneficial to improving power quality and operational reliability in complex underwater environments.

[0029] Fourth, this application adopts a hydraulically compensated power supply wet tank structure. By adjusting the pressure balance inside and outside the wet tank through the hydraulic compensator, the thickness of the power supply shell can be reduced, which is beneficial to reducing the volume and weight of the underwater power supply and increasing the power density. Attached Figure Description

[0030] Figure 1This is a schematic diagram of the overall structure of the power supply and distribution system for ROV provided in this application; Figure 2 This is a schematic diagram of the closed-loop voltage regulation method based on dynamic link identification and adaptive weight update provided in this application.

[0031] Labeling Explanation: 1-Ship Electrical System, 2-Medium Voltage Intermediate Frequency Power Supply, 3-Wind, 4-Umbilical Cable, 5-High Voltage Watertight Connector, 6-Intermediate Frequency Transformer, 7-Rectifier Module, 8-Contaminator, 9-600VDC Watertight Connector, 10-Power Supply Wet Chamber, 11-Oil Pipe, 12-Hydraulic Pressure Compensator, 13-First Watertight Connector, 14-Second Watertight Connector, 15-Third Watertight Connector, 16-Fourth Watertight Connector, 17-DC / DC Module, 18-AC / DC Circuit Board, 19-Control Board, 20-Low Voltage Load Watertight Connector, 21-Power Supply Control Chamber. Detailed Implementation

[0032] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0033] like Figure 1 As shown, this embodiment provides a power supply and distribution system for ROV, mainly including a ship power supply 1, a medium-voltage intermediate frequency power supply 2, a winch 3, an umbilical cable 4, a high-voltage watertight connector 5, an intermediate frequency transformer 6, a rectifier module 7, a contactor 8, a 600VDC watertight connector 9, a power supply wet compartment 10, an oil pipe 11, an oil pressure compensator 12, a first watertight connector 13, a second watertight connector 14, a third watertight connector 15, a fourth watertight connector 16, a DC / DC module 17, an AC / DC circuit board 18, a control board 19, a low-voltage load watertight connector 20, and a power control compartment 21.

[0034] Shipboard electrical system 1 is the power output of the surface vessel, typically a three-phase industrial frequency power supply. It serves as the input to this power distribution system, supplying power to the medium-voltage intermediate frequency power supply 2 via cables. In this embodiment, shipboard electrical system 1 is a low-voltage three-phase 380VAC / 50Hz AC power supply.

[0035] The medium-voltage intermediate-frequency power supply 2 is a power conversion device that converts the three-phase industrial frequency power supplied by the surface vessel into medium-voltage intermediate-frequency power. One end of the medium-voltage intermediate-frequency power supply 2 is connected to the ship's power supply 1, and the other end is connected to the umbilical cable 4 on the winch 3. In this embodiment, the medium-voltage intermediate-frequency power supply 2 converts the ship's power supply into medium-voltage 4160VAC / 400Hz AC power. The medium-voltage intermediate-frequency power supply 2 is equipped with a closed-loop voltage regulator and a power conversion module. The closed-loop voltage regulator executes a closed-loop voltage regulation algorithm based on feedback data from the ROV end and outputs a PWM duty cycle command to control the output voltage of the power conversion module.

[0036] The winch 3 is an umbilical cable deployment and retrieval device used for laying and recovering the umbilical cable 4. The umbilical cable 4 is an ROV power transmission cable, with one end connected to the medium-voltage intermediate frequency power supply 2 via the winch 3, and the other end connected to the high-voltage watertight connector 5 at the underwater end of the ROV. The umbilical cable 4 also contains signal core wires or fiber optic communication channels for transmitting feedback data collected by the ROV. The high-voltage watertight connector 5 is a sealed power transmission component operating in an underwater environment, connected at one end to the umbilical cable 4 and at the other end to the intermediate frequency transformer 6.

[0037] The intermediate frequency transformer 6 is a device that converts high-voltage electricity into low-voltage alternating current. One end is connected to the high-voltage watertight connector 5, and the other end is connected to the rectifier module 7. The intermediate frequency transformer 6 operates at an intermediate frequency and is smaller in size than a power frequency transformer, which is beneficial for the lightweight design of underwater equipment.

[0038] The rectifier module 7 rectifies the low-voltage intermediate-frequency AC power output from the intermediate-frequency transformer 6 into 600VDC DC power (i.e., DC bus) for the load. In this embodiment, a 12-pulse uncontrolled rectifier module is preferably used. This module consists of two three-phase full-wave bridge rectifier circuits with a total of 12 diodes. Each bridge includes three common-cathode diodes (output positive terminal) and three common-anode diodes (output negative terminal). 12-pulse rectification helps reduce output voltage ripple and improves power supply quality.

[0039] Contactor 8 is used to control the on / off state of the power output link. The 600VDC watertight connector 9 is a sealed power transmission component that operates in an underwater environment, used to connect the inside and outside of the power supply chamber 10 to supply power to the load.

[0040] The power supply wet tank 10 is a sealed power supply compartment with hydraulic compensation, housing the intermediate frequency transformer 6 and the rectifier module 7. The power supply wet tank 10 is filled with transformer oil and connected to the hydraulic compensator 12 via an oil pipe 11. The oil pipe 11 connects the power supply wet tank 10 to the hydraulic compensator 12. The hydraulic compensator 12 is a device for regulating system pressure. Connected to the power supply wet tank 10 via the oil pipe 11, it adjusts the oil pressure according to the different depths of the ROV, ensuring that the internal pressure of the power supply wet tank 10 remains consistent with the external seawater pressure. This reduces the thickness of the power supply wet tank 10's outer shell, thereby reducing the volume and weight of the underwater power supply.

[0041] The first watertight connector 13, the second watertight connector 14, the third watertight connector 15, and the fourth watertight connector 16 are all sealed power and signal transmission components operating in an underwater environment. They are located between the power supply wet compartment 10 and the power control compartment 21 to enable power transmission and signal interaction between the two compartments. Specifically, the third watertight connector 15 is used to transmit 600VDC DC bus power from the power supply wet compartment 10 to the control compartment 21, while the first watertight connector 13, the second watertight connector 14, and the fourth watertight connector 16 are used for the transmission of control signals and status signals.

[0042] DC / DC module 17 is a DC power converter located in the power control compartment 21. It converts 600VDC to 48VDC for use by low-voltage loads such as cameras and lights. The low-voltage load watertight connector 20 is a sealed power and signal transmission component designed for underwater operation. The input of DC / DC module 17 is connected to the 600VDC bus via the third watertight connector 15, and the output supplies power to low-voltage loads via the low-voltage load watertight connector 20. AC / DC circuit board 18 is a rectifier power module located in the power control compartment 21. It rectifies the low-voltage intermediate-frequency AC power output from the intermediate-frequency transformer 6 into DC power required by the control board 19, thus powering the control board 19.

[0043] Control board 19 is a power control board located inside power control compartment 21, used for power control and signal acquisition. Control board 19 acquires the 600VDC DC bus voltage, load current, and load branch status of the ROV end in real time, and uploads the acquired data to the surface medium-voltage intermediate frequency power supply 2 via the signal core wire or fiber optic communication channel in umbilical cable 4.

[0044] The power control compartment 21 is an underwater pressure-resistant chamber that provides installation space for high-precision components related to power control. The control board 19, DC / DC module 17, and AC / DC circuit board 18 are all housed within the control compartment 21.

[0045] The workflow of this system is as follows: 1) The medium-voltage intermediate-frequency power supply 2 converts the low-voltage power frequency electrical energy provided by the surface mother ship into medium-voltage intermediate-frequency electrical energy, which is then transmitted to the intermediate-frequency transformer 6 via the umbilical cable 4 and the high-voltage watertight connector 5. Increasing the transmission voltage helps reduce cable loss, and increasing the transmission frequency helps reduce the size of the intermediate-frequency transformer 6.

[0046] 2) The intermediate frequency transformer 6 steps down the intermediate voltage and transmits it to the 12-pulse uncontrolled rectifier module 7. The rectifier module rectifies the AC output of the transformer into 600V DC. After the control board 19 controls the contactor 8 to conduct, it supplies power to high-power loads such as the thruster and hydraulic power source. At the same time, the 600V DC is transmitted to the power control compartment 21 through the first watertight connector 13 and the third watertight connector 15. It is then converted into 48V DC by the DC / DC module 17 to supply low-voltage loads such as cameras and lights.

[0047] 3) Control board 19 collects real-time data such as the DC bus voltage and load current at the ROV end and feeds the collected data back to the medium-voltage intermediate frequency power supply 2 on the water surface. The closed-loop voltage regulator of the medium-voltage intermediate frequency power supply 2 executes a closed-loop voltage regulation method based on dynamic link identification and adaptive weight update according to the feedback information. By comprehensively analyzing the voltage change trend at the ROV end, the impedance change of the power supply link, and the load disturbance, it realizes the active adjustment of the medium-voltage intermediate frequency output voltage.

[0048] 4) The hydraulic compensator 12 adjusts the oil pressure according to different diving depths to ensure that the pressure inside the power wet tank 10 is always consistent with the external seawater pressure.

[0049] The following details the closed-loop voltage regulation method based on dynamic link identification and adaptive weight update, such as... Figure 2 As shown, the method includes the following steps: Step S1: Acquire ROV terminal operating status and model power supply voltage status.

[0050] In the kth sampling period, control board 19 acquires the 600VDC DC bus voltage at the ROV terminal. Load current The signal is transmitted via the signal core wire or fiber optic communication channel within the umbilical cable 4. The medium-voltage intermediate-frequency power supply 2 locally acquires the effective value of its three-phase output line voltage at the water surface end. The surface controller aligns the data from both ends according to the timestamps and constructs a state vector. :

[0051] in, The changes in bus voltage and load current (first-order changes) measured in adjacent sampling periods can be expressed as:

[0052]

[0053] To avoid conflicts in direct calculation of AC and DC voltages, an AC-DC equivalent conversion factor is introduced to convert the AC voltage output from the medium-voltage intermediate frequency power supply at the water surface to the DC bus side at the ROV end, establishing the following remote voltage relationship:

[0054] in, The AC-DC equivalent conversion factor is determined by the turns ratio, rectification parameters and calibration efficiency of the intermediate frequency transformer. In specific applications, it can be calibrated by no-load or known load tests. The overall voltage drop of the umbilical cable, intermediate frequency transformer, and rectifier module converted to the 600VDC side is identified online in step S3.

[0055] Step S2: Based on the current feedback state vector Predict the trends of ROV terminal voltage and load current changes in the next cycle.

[0056] The first-order voltage change in the current period is calculated sequentially based on the DC bus voltage measured in adjacent sampling periods. and second-order voltage change And based on the load current measured in adjacent sampling periods, the first-order current change in the current period is calculated sequentially. and second-order current change The second-order changes of the two are expressed as follows:

[0057]

[0058] The predicted value of the ROV terminal voltage trend for the next cycle is obtained by using discrete trend extrapolation. and predicted load current , respectively represented as:

[0059]

[0060] In this embodiment, to suppress measurement noise, for , , and After applying amplitude limiting or low-pass filtering, it is used in the prediction.

[0061] Step S3: Identify dynamic parameters of the system power supply link.

[0062] Constructing a discrete parameter model of the system power supply link And perform online identification to obtain the updated model parameters for the next cycle. .in, This is the equivalent resistance of the umbilical cable conductor resistance and the circuit contact resistance. The equivalent inductance is formed by the distributed inductance of the umbilical cable, the leakage inductance of the intermediate frequency transformer, and the inductance of the filter circuit. Due to the inherent voltage drop bias of the intermediate frequency transformer and rectifier module, the three parameters need to be converted to the DC bus side of the ROV terminal when participating in the calculation. and The initial value can be calculated based on the unit length parameter, the actual cable length, and the transformer ratio. The initial value can be calibrated by no-load or known load tests.

[0063] In one possible implementation, for Online identification Specifically, this includes: the effective value of the three-phase output line voltage based on the synchronous sampling in step S1. and ROV terminal DC bus voltage Calculate the observed values ​​of the overall voltage drop of the power supply link. , is represented as:

[0064] definition And use discrete parameter models to predict the overall pressure drop. , is represented as:

[0065] exist In the expansion, Indicates resistive voltage drop. This represents the dynamic voltage drop caused by changes in current. This is the duration of the sampling period.

[0066] Calculate the overall pressure drop observation value Compared with the predicted value The identification error between The model parameters are iteratively updated using an online update method with normalization terms and physical boundary projections, as shown below:

[0067] in, Update the gain matrix for pre-defined diagonal positive definite parameters, in the form of: , The update rates of equivalent resistance, equivalent inductance, and fixed voltage drop bias are controlled separately. Each parameter is tuned experimentally based on the sampling period, parameter dimensions, measurement noise, and convergence speed. To prevent positive numbers with a denominator of zero; The physical boundary projection operator is used to project the physical boundary. , and Limited to the physically feasible range determined by cable parameters and equipment testing. Inside.

[0068] In other implementations, the rate of parameter change can be further calculated. It is used to determine whether the power supply link is undergoing rapid changes.

[0069] Step S4: Calculate the feedback error compensation component, voltage trend compensation component, link change compensation component, and load disturbance compensation component respectively.

[0070] (1) Calculate the reference voltage value of the DC bus at the ROV end. and measured values The difference between them yields the current feedback error compensation component. .

[0071] (2) Calculate the DC bus voltage at the ROV terminal measured in the current sampling period. The predicted value of the ROV terminal voltage trend for the next cycle calculated in step S2. The difference between them yields the voltage trend compensation component. .

[0072] When the predicted value When the voltage is below the target voltage lower limit (trend judgment threshold), This increases the demand for subsequent boost voltage regulation. In this embodiment, the lower limit of the target voltage is set to... This is used to determine whether the predicted voltage has entered the undervoltage regulation region. This is the voltage regulation dead zone. This value is a preset control parameter, and its value is determined based on the allowable voltage fluctuation range of the bus, voltage sampling error, rectifier ripple, and the suppression requirements for frequent system adjustments.

[0073] (3) Update the parameter values ​​based on the identification And the predicted value of the ROV terminal load current for the next cycle calculated in step S2. Calculate the predicted comprehensive voltage drop of the power supply link for the next cycle. , is represented as:

[0074] Calculate the difference between the predicted comprehensive voltage drop of the power supply link in the next cycle and the current cycle to obtain the link variation compensation component. .

[0075] (4) Estimate the voltage compensation component corresponding to the load disturbance based on the first and second order changes of the load current calculated in steps S1 and S2. , is represented as:

[0076] in, and This is the current-voltage disturbance conversion factor calibrated through a load step test.

[0077] The four compensation components respectively represent the current feedback error, voltage change trend, link parameter change, and load disturbance, and are all unified as voltage values ​​referred to the 600VDC side:

[0078] Step S5: Adaptively adjust and normalize the weights of each compensation component.

[0079] Calculate the moving root mean square (RMS) of each compensation component, and obtain the state significance based on the ratio of the absolute value of the compensation component to the corresponding moving RMS. Used for Dimensionless representation, expressed as:

[0080] in, Represents the absolute value of a scalar; To prevent positive numbers with a denominator of zero; The moving root mean square of the i-th type of compensation component is expressed as:

[0081] in, It is the square of the moving mean square value of the i-th type of compensation component in the previous period. Let be the squared value of the i-th type of compensation component in the current period. This is the smoothing coefficient.

[0082] The unnormalized weights are calculated by combining the baseline weights of each compensation component and the state sensitivity coefficient. , is represented as:

[0083] in, The non-negative reference weights for the i-th type of compensation components are used to determine the basic control emphasis of the system in steady state or weak disturbance state; The state sensitivity coefficient of the i-th type of compensation component determines the rate at which the weight of the corresponding compensation component increases as it increases.

[0084] For unnormalized weights Normalization is performed to obtain the weights actually used. :

[0085] After normalization, it satisfies And the sum of all weights is 1.

[0086] Step S6: Constrained PID closed-loop voltage regulation control based on adaptive compensation.

[0087] Based on the weights obtained in step S5 and the four compensation components obtained in step S4 The corrected voltage reference value for the DC bus at the ROV end is generated by weighted summation. This value simultaneously includes four factors: feedback error, voltage trend, link variation, and load disturbance.

[0088] in, The corrected target value for the 600VDC bus at the ROV end; and The upper and lower limits are set based on the allowable voltage range of the ROV load, i.e., the hard limit boundary of the corrected target voltage, to ensure that the reference value after dynamic compensation does not exceed the safe voltage range allowed by the ROV load. This represents the amplitude limiting function.

[0089] Based on the corrected voltage reference value Compared with the measured bus voltage Calculate PID error:

[0090] This error is addressed by adjusting the output voltage of the medium-voltage intermediate-frequency power supply via PID control, specifically by establishing a PID control output with integral limiting:

[0091] in, The output control quantity is the PID controller; , , The first The proportional, integral, and differential gain of the period.

[0092] The PID gain is slowly adjusted within a preset safety range based on the error amplitude and error variation.

[0093]

[0094]

[0095] in, , , For gain scheduling rate; The nominal error scale is a preset nominal scale used to make the PID error dimensionless, which can be determined by rated load and load step test. Indicates upper and lower limit constraints; The PWM value is 1 when it is not saturated and 0 when it is saturated. Therefore, sudden load changes cause... or When it increases, the next cycle and Increase within the limit; Update slowly only when the system is not saturated.

[0096] The PID output is converted into a PWM duty cycle command for medium-voltage intermediate-frequency power supply 2 after proportional conversion and limiting:

[0097] in, This is the reference duty cycle corresponding to the rated operating point. For control quantity conversion coefficient, and These are the upper and lower limits of the allowable duty cycle for the power conversion module.

[0098] The aforementioned closed-loop voltage regulation method achieves stable control of the DC bus voltage at the ROV end by actively adjusting the output voltage of the medium-voltage intermediate frequency power supply at the water surface end. This eliminates the need for an additional active voltage regulation and conversion stage underwater, which helps to simplify the structure of underwater equipment and reduce its size and weight.

[0099] It should be noted that, in order to avoid conflicts in the direct calculation of AC-side and DC-side electrical quantities, this method introduces an AC-DC equivalent conversion factor. The AC voltage output from the medium-voltage intermediate-frequency power supply on the water surface, the equivalent resistance and equivalent inductance of the power supply link, the fixed voltage drop bias of the intermediate-frequency transformer and rectifier module, and the comprehensive voltage drop of the power supply link are all converted to the 600VDC DC bus side at the ROV end. Simultaneously, the feedback error compensation component, voltage trend compensation component, link change compensation component, and load disturbance compensation component are unified into voltage dimensions converted to the 600VDC DC bus side, enabling parameter identification and control quantity calculation of the AC transmission link and the DC load side under the same DC side model; the DC bus voltage directly sampled at the ROV end... Load current These are native physical quantities on the DC side and no conversion operation is performed.

[0100] The above descriptions are merely preferred embodiments of this application, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A power supply and distribution system for ROVs, characterized in that, It includes a medium-voltage intermediate frequency power supply, an umbilical cable, and an intermediate frequency transformer, a rectifier module, and a control board located at the ROV end. The intermediate frequency transformer and the rectifier module are placed in the power supply wet chamber, and the control board is placed in the power supply control chamber. The power supply wet chamber and the power supply control chamber are connected by a watertight connector to realize the transmission of electrical energy and signals. The input terminal of the medium-voltage intermediate frequency power supply is connected to the ship's power supply, and the output terminal is connected to the primary side of the intermediate frequency transformer via the umbilical cable. The secondary side of the intermediate frequency transformer is connected to the input terminal of the rectifier module, and the output terminal of the rectifier module forms a DC bus for use by the ROV end load. The control board is used to collect DC bus voltage and load current, and feed them back to the medium-voltage intermediate frequency power supply; The medium-voltage intermediate frequency power supply is equipped with a closed-loop voltage regulator. The closed-loop voltage regulator is configured to: predict the ROV terminal voltage and load current change trend in the next cycle based on the current feedback data, and calculate the feedback error compensation component, voltage trend compensation component, link change compensation component and load disturbance compensation component respectively by combining the effective value of the three-phase output line voltage collected by the local terminal. The weights of each compensation component are adaptively adjusted and weighted summation is performed to generate a corrected voltage reference value for the DC bus at the ROV end. The output voltage of the medium-voltage intermediate frequency power supply is adjusted by PID control based on the deviation between the corrected voltage reference value and the measured bus voltage.

2. The power supply and distribution system for ROV according to claim 1, characterized in that, It also includes a hydraulic compensator. The power supply wet chamber is filled with transformer oil. The hydraulic compensator is connected to the power supply wet chamber through an oil pipe and is used to adjust the internal pressure of the power supply wet chamber to balance the pressure inside and outside the chamber.

3. The power supply and distribution system for ROV according to claim 1, characterized in that, It also includes a DC / DC module and an AC / DC circuit board, both of which are housed within the power control compartment. The input terminal of the DC / DC module is connected to the DC bus via the watertight connector, and the output terminal outputs low-voltage DC power to supply power to the low-voltage load at the ROV end. The input terminal of the AC / DC circuit board is connected to the intermediate frequency AC power output by the intermediate frequency transformer through the watertight connector, and the output terminal is electrically connected to the control board to rectify and convert the intermediate frequency AC power into low-voltage DC power to supply power to the control board.

4. The power supply and distribution system for ROV according to claim 1, characterized in that, The method for predicting the ROV terminal voltage and load current change trends in the next cycle based on current feedback data is the same. The method for predicting the ROV terminal voltage trend in the next cycle includes: The first-order voltage change in the current period is calculated sequentially based on the DC bus voltage measured in adjacent sampling periods. and second-order voltage change ; The predicted value of the ROV terminal voltage trend for the next cycle is obtained by using discrete trend extrapolation. Represented as: in, This is the DC bus voltage at the ROV terminal measured during the current sampling period.

5. The power supply and distribution system for ROV according to claim 1, characterized in that, Calculating the feedback error compensation component and the voltage trend compensation component includes: The difference between the reference voltage value and the measured voltage value of the DC bus at the ROV end is calculated to obtain the feedback error compensation component. ; The difference between the DC bus voltage at the ROV terminal measured in the current sampling period and the predicted value of the ROV terminal voltage trend in the next period is calculated to obtain the voltage trend compensation component. .

6. The power supply and distribution system for ROV according to claim 1, characterized in that, Calculating the link change compensation component includes: Constructing a discrete parameter model of the system power supply link And perform online identification to obtain the updated model parameters for the next cycle. ; Updated values ​​based on identified parameters And the predicted value of the ROV terminal load current in the next cycle Calculate the predicted comprehensive voltage drop of the power supply link for the next cycle. , is represented as: Calculate the difference between the predicted comprehensive voltage drop of the power supply link in the next cycle and the current cycle to obtain the link variation compensation component. ; in, This is the equivalent resistance of the umbilical cable conductor resistance and the circuit contact resistance. The equivalent inductance is formed by the distributed inductance of the umbilical cable, the leakage inductance of the intermediate frequency transformer, and the inductance of the filter circuit. This is the inherent voltage drop bias of the intermediate frequency transformer and rectifier module; This refers to the ROV terminal load current measured during the current sampling period. This is the duration of the sampling period.

7. The power supply and distribution system for ROV according to claim 6, characterized in that, The discrete parameter model is identified online to obtain the updated model parameters for the next period. ,include: RMS value of three-phase output line voltage based on synchronous sampling and ROV terminal DC bus voltage Calculate the observed values ​​of the overall voltage drop of the power supply link. The discrete parameter model is used to predict the overall pressure drop. ,in Represented as: Calculate the overall pressure drop observation value Compared with the predicted value The identification error between The model parameters are iteratively updated using an online update method with normalization terms and physical boundary projections, as shown below: in, For AC-DC equivalent conversion factors; Update the gain matrix for pre-defined diagonal positive definite parameters; , The change in load current measured in adjacent sampling periods; To prevent positive numbers with a denominator of zero; This is the physical boundary projection operator.

8. The power supply and distribution system for ROV according to claim 1, characterized in that, Calculating the load disturbance compensation component includes: The first-order current change in the current period is calculated sequentially based on the load current measured in adjacent sampling periods. and second-order current change ; Estimate the voltage compensation component corresponding to the load disturbance based on the first and second order changes of the load current. , is represented as: in, and This is the current-voltage disturbance conversion factor.

9. The power supply and distribution system for ROV according to claim 1, characterized in that, Adaptively adjust the weights of each compensation component, including: Calculate the moving root mean square of each compensation component. The state significance is obtained based on the ratio of the absolute value of the compensation component to the corresponding moving average root. , is represented as: Combine the benchmark weights of each compensation component and state sensitivity coefficient Calculate unnormalized weights , is represented as: For the unnormalized weights Perform normalization so that the sum of all weights is 1; in, These correspond to the feedback error compensation component, voltage trend compensation component, link change compensation component, and load disturbance compensation component, respectively. To prevent positive numbers with a denominator of zero.

10. The power supply and distribution system for ROV according to claim 9, characterized in that, Normalized weights With corresponding compensation components Weighted summation is used to generate the corrected voltage reference value for the DC bus at the ROV end. , is represented as: in, The initial voltage reference value for the DC bus at the ROV end; and To correct the upper and lower limits of the voltage reference value; This represents the amplitude limiting function.

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