Direct current networking new energy ship shore power grid connection anti-disturbance control method and system

Abstract

The invention relates to a DC networking new energy ship shore power grid-connected anti-disturbance control method and system, and the method comprises the steps: calculating an angular frequency and a phase angle based on a virtual synchronous generator model, inputting the angular frequency deviation into an extended state observer, and estimating the total disturbance in real time; performing feedforward compensation fusion on the original active instruction of the virtual synchronous generator and the total disturbance observation value to generate an anti-disturbance active power reference instruction; running SPWM modulation according to the direct current side signal and the active instruction, and generating a modulation signal to control power conversion; the driving signal is fed to a power grid after being amplified and filtered; meanwhile, output current is collected and compared with reference current synthesized by phase angles, zero static error tracking is achieved through a quasi-proportional resonance controller, and compensation signals are generated for real-time correction modulation; the grid-connected power converter adopts a new-generation power electronic switching device SiC-MOSFET, and the efficiency can exceed 98%. Compared with the prior art, the system has the advantages of high stability, high electric energy quality, high reliability and the like.

Description

Technical Field

[0001] This invention relates to the field of microgrid technology, and in particular to an anti-disturbance control method and system for DC grid-connected new energy ships' shore power grid connection. Background Technology

[0002] When a DC-connected new energy vessel docks, its distributed power supply needs to be connected to the grid according to the shore power parameters. This grid connection process not only poses a potential impact on the stable operation of the shore power grid, but also brings a series of challenges to the stable operation of the vessel's DC grid power supply system itself.

[0003] Distributed energy sources used in new energy ships, such as photovoltaic power generation, are characterized by instability, intermittency, and low inertia. These characteristics make it easy for ships to interfere with the safe operation of the shore power grid during grid connection, and also affect the stability of the ship's DC grid power supply system itself. Therefore, research on control strategies for ship DC grid power supply systems is particularly important. In existing technologies, virtual synchronous generator control strategies are widely used, which can improve the system's inertia to a certain extent and reduce the impact on the main power grid.

[0004] However, in practical applications, existing control methods still suffer from insufficient adaptability in active power control, especially during the moment of grid connection when the system experiences significant shocks, resulting in a longer time required for the system to reach stable operation. Furthermore, establishing a stable DC bus voltage in DC grid systems also presents challenges, necessitating further optimization of control strategies. When sudden changes occur in ship operating conditions, systems using fixed control parameters are prone to oscillations, affecting power supply quality and system reliability.

[0005] Currently, research on DC grid connection for new energy ships connecting to shore power mainly focuses on energy management during berthing. In contrast, research on the impact of ship connection to the main shore power grid and ensuring the stable operation of ship DC grid systems remains urgently needed. Existing related technical solutions largely focus on achieving efficient energy distribution and improving the operational efficiency of the ship's power grid, but there are still shortcomings in dealing with grid connection impacts, improving system stability, and dynamic response performance. Therefore, how to effectively improve the inertial support capability of the DC grid power supply system for new energy ships and reduce the impact of the grid connection process on the ship's DC grid system and the main shore power grid is a technical problem that needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art by providing a disturbance rejection control method and system for DC grid-connected new energy ship shore power grid connection. By introducing active disturbance rejection control into the power outer loop of the virtual synchronous generator, an extended state observer that can estimate and compensate for the total disturbance of the system in real time is constructed, thereby effectively responding to the grid impact at the moment of ship shore power grid connection and improving the system's inertial support capability and disturbance rejection performance.

[0007] The objective of this invention can be achieved through the following technical solutions: According to one aspect of the present invention, a disturbance rejection control method for ship-to-shore power grid connection is provided, the specific steps of which include: S1. The sampling module collects the input voltage and current signals from the DC side and the voltage and current signals from the grid side in real time, and converts them into electrical signals that can be processed by the control module. S2. A virtual synchronous generator model is constructed based on the rotor motion equation of the synchronous generator. The angular frequency and phase angle of the virtual synchronous generator are calculated according to the voltage and current signals of the grid side. The deviation between the angular frequency and the rated angular frequency is input to the extended state observer constructed based on linear active disturbance rejection control technology to estimate and output the total disturbance observation value in real time. S3. Calculate the original active power command of the virtual synchronous generator model and perform feedforward compensation fusion with the total disturbance observation to generate the disturbance-resistant active power reference command. S4. Based on the converted DC-side signal in S1 and the active power reference command in S3, run the SPWM modulation algorithm to generate a modulation signal, and use the modulation signal to control the operation of the switching transistor in the power conversion module. S5. The modulation signal is amplified by the driving module, which drives the power conversion module to generate AC power, and the high-frequency harmonics are filtered out by the filtering module before being fed to the power grid. S6. The sampling module collects the inverter output current filtered in S5 in real time and compares it with the reference current signal synthesized from the phase angle and rated voltage generated by S2. The quasi-proportional resonant controller is used to perform zero steady-state error tracking of the error signal to generate a current compensation signal for real-time correction of the modulation signal.

[0008] Furthermore, the adaptive step for the gain coefficient of the extended state observer in S2 includes: Based on the input and output data of the control module, the maximum Lyapunov exponent, which characterizes the stability of the system, is estimated in real time using the recursive least squares method. When the maximum Lyapunov exponent is greater than the preset instability threshold, the parameter adjustment mechanism is triggered; The adjustment amount of the gain coefficient of the extended state observer is calculated using the gradient descent method, and the gain coefficient is updated based on the adjustment amount.

[0009] Furthermore, the virtual synchronous generator model in S2 includes calculating the angular frequency and phase angle of the virtual synchronous generator, expressed as: , in, J For rotational inertia, ω The angular frequency of the virtual synchronous generator. ω 0 is the rated angular frequency. For reference active power, P 0 For input active power, The damping coefficient is... The output phase angle of the virtual synchronous generator.

[0010] Furthermore, the virtual synchronous generator model also includes adjusting the value of the virtual input active power based on the difference between the angular frequency of the virtual synchronous generator and the rated angular frequency; and adjusting the amplitude of the AC voltage expected to be output by the inverter of the virtual synchronous generator based on the difference between the reference reactive power and the input reactive power of the virtual synchronous generator.

[0011] Furthermore, the extended state observer in S2, constructed based on linear active disturbance rejection control technology, calculates the offset observation value according to the deviation between the angular frequency and the rated angular frequency. The offset observation value includes a first offset observation value, a second offset observation value, and a third offset observation value, wherein the third offset observation value is the total disturbance observation value, expressed as: , , , in, , and These are the first offset observation, the second offset observation, and the third offset observation, respectively. h This is for simulating step size; , and The observer gain coefficient; The dynamics of the controlled object are known; and Both are nonlinear functions relating to the deviation of the angular frequency from the rated angular frequency; k For time indexing; This represents the deviation of the angular frequency from the rated angular frequency. The gain coefficient of the control quantity; For the first k One control cycle.

[0012] Furthermore, in S3, the specific process of feedforward compensation fusion is as follows: subtract the total disturbance observation value scaled by the compensation factor from the original active power command to generate the disturbance-resistant active power reference command.

[0013] Furthermore, in step S6, the specific steps for obtaining the input value of the quasi-proportional resonant controller include: Based on the system output voltage amplitude command and phase angle generated by the virtual synchronous generator control, a three-phase symmetrical reference voltage signal is synthesized. The three-phase reference voltage signal is compared with the sampled actual output three-phase voltage signal of the inverter, and the deviation signal is used as the input of the voltage outer loop. The output of the voltage outer loop is used as the reference signal of the current inner loop. The current inner loop reference signal is compared with the sampled actual output current signal of the inverter to obtain the current tracking error signal. The current tracking error signal is input to the quasi-proportional resonant controller.

[0014] Furthermore, the transfer function of the quasi-proportional resonant controller is, based on proportional control, a resonant control with a specified width at the fundamental frequency of the power grid is superimposed, and its expression is: , in, K p This is the proportionality coefficient. K i The integral coefficient is... ω s This is the cutoff frequency of the low-pass filter. ω 1 represents the fundamental angular frequency of the power grid.

[0015] Furthermore, the method also includes a DC bus voltage stabilization step: The bidirectional DC / DC converter employs a dual-loop control structure consisting of an outer voltage loop and an inner battery current loop. The DC bus voltage is the controlled object, and a reference value for the inner current loop is generated by a PI regulator. The battery current is then the controlled object, and a duty cycle control signal is generated by a PI regulator to maintain the stability of the DC bus voltage.

[0016] According to another aspect of the present invention, an anti-disturbance control system for ship-to-shore power grid connection is provided, the system comprising: a sampling module, a control module, a drive module, a power conversion module, and a filtering module; The sampling module is used to acquire voltage and current signals from the DC side and the grid side in real time, and to perform signal conversion and processing. The control module is connected to the sampling module and is used to calculate the angular frequency and phase angle based on the virtual synchronous generator model; run the extended state observer to estimate the total system disturbance in real time; perform feedforward compensation fusion to generate the disturbance-resistant active power reference command; run the SPWM modulation algorithm to generate the modulation signal; and execute the current tracking algorithm based on quasi-proportional resonance control to generate the current compensation signal. The drive module is connected to the control module and is used to receive the modulation signal and generate a weak drive signal; A power conversion module, connected to the drive module, is used to perform power conversion based on the drive weak current signal to generate alternating current. The filtering module, connected to the power conversion module, is used to filter out high-frequency harmonics in the AC power and feed electrical energy into the power grid.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) Enhance the system’s inertial support and anti-disturbance capability: By adopting the improved virtual synchronous generator technology based on active disturbance rejection control, an extended state observer is introduced into the active-frequency control loop of the virtual synchronous generator, which can estimate and compensate for the total disturbance of the system in real time, effectively enhancing the inertial support capability of the ship’s DC grid power supply system, improving the system’s anti-disturbance performance in the moment of grid connection, and overcoming the defect of poor adaptability of traditional virtual synchronous generator active power control.

[0018] (2) Achieve rapid stability and dynamic performance optimization: Deeply integrate active disturbance rejection control technology with virtual synchronous generator control, and actively offset the influence of internal and external disturbances through feedforward compensation mechanism, so that the system can quickly recover stability when subjected to grid connection impact or load change, shorten the time required for the system to reach a stable operating state, and improve the dynamic response performance under strong coupling and multi-source disturbance conditions.

[0019] (3) Ensure the continuous stability of the control system: The self-tuning method of active disturbance rejection parameters based on Lyapunov exponent is adopted. By estimating the maximum Lyapunov exponent of the system in real time and dynamically adjusting the observer gain coefficient, the control system is ensured to remain stable under different operating conditions. This solves the problem of system oscillation caused by fixed control parameters when the ship's operating conditions change abruptly, and improves the adaptability and reliability of the system.

[0020] (4) Improve power quality and harmonic suppression effect: Quasi-proportional resonant control technology is adopted in the dual closed-loop control. By superimposing resonant control at the fundamental frequency of the power grid on the basis of proportional control, the AC signal is tracked without steady-state error, avoiding the power coupling defect under the traditional dq coordinate system. It can still maintain good control effect under nonlinear load conditions and ensure that the harmonic distortion rate is maintained within the standard range.

[0021] (5) Enhance the overall reliability of the system: By leveraging the voltage support function of the energy storage unit in the DC grid structure, and combining the dual-loop control of the voltage outer loop and current inner loop of the bidirectional DC / DC converter, precise and stable control of the DC bus voltage is achieved, effectively reducing the intermittent impact of the photovoltaic power generation module, ensuring the stability of the DC bus voltage, and thus improving the operational reliability of the entire ship DC grid power supply system. Attached Figure Description

[0022] Figure 1 A flowchart of an anti-disturbance control method for DC grid-connected new energy ship shore power grid connection; Figure 2 A diagram showing the DC network structure for new energy ships; Figure 3 For DC grid-connected new energy ship shore power grid-connected SiC-MOSFET converter topology; Figure 4 This is a block diagram of a DC-networked ship control system based on a self-disturbance rejection virtual synchronous generator. Figure 5 This is a schematic diagram of the active disturbance rejection control principle. Figure 6 Control block diagram for quasi-PR control; Figure 7 The phase tracking results are for a DC ship power supply system based on virtual synchronous generator control. Figure 8 The results of phase tracking for DC grid-connected ship control based on active disturbance rejection virtual synchronous generators; Figure 9 The grid-side voltage results are for a DC ship power supply system based on virtual synchronous generator control. Figure 10 The voltage results for the DC-connected ship control network side are based on a self-disturbance rejection virtual synchronous generator. Detailed Implementation

[0023] 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, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] like Figure 1 The diagram illustrates an anti-disturbance control method for DC grid-connected new energy ship shore power grid integration. The specific steps include: S1. The sampling module collects the input voltage and current signals from the DC side and the voltage and current signals from the grid side in real time, and converts them into electrical signals that can be processed by the control module. S2. A virtual synchronous generator model is constructed based on the rotor motion equation of the synchronous generator. The angular frequency and phase angle of the virtual synchronous generator are calculated based on the voltage and current signals on the grid side. The deviation between the angular frequency and the rated angular frequency is input to the extended state observer constructed based on linear active disturbance rejection control technology to estimate and output the total disturbance observation value in real time. S3. Calculate the original active power command of the virtual synchronous generator model and perform feedforward compensation fusion with the total disturbance observation to generate the disturbance-resistant active power reference command. S4. Based on the converted DC-side signal in S1 and the active power reference command in S3, run the SPWM modulation algorithm to generate a modulation signal, and use the modulation signal to control the operation of the switching transistor in the power conversion module. S5. The modulated signal is amplified by the driving module, which drives the power conversion module to generate AC power. After the high-frequency harmonics are filtered out by the filtering module, the power is fed to the grid. S6. The sampling module collects the inverter output current filtered in S5 in real time and compares it with the reference current signal synthesized from the phase angle and rated voltage generated by S2. The quasi-proportional resonant controller is used to perform zero steady-state error tracking of the error signal to generate a current compensation signal for real-time correction of the modulation signal.

[0025] An anti-disturbance control system for ship-to-shore power grid connection using this method, such as Figure 2 As shown, it includes: a sampling module, a control module, a drive module, a power conversion module, and a filtering module; The sampling module is used to acquire voltage and current signals from the DC side and the grid side in real time, and to perform signal conversion and processing. The control module is connected to the sampling module and is used to calculate the angular frequency and phase angle based on the virtual synchronous generator model; run the extended state observer to estimate the total system disturbance in real time; perform feedforward compensation fusion to generate the disturbance-resistant active power reference command; run the SPWM modulation algorithm to generate the modulation signal; and execute the current tracking algorithm based on quasi-proportional resonance control to generate the current compensation signal. The drive module is connected to the control module and is used to receive the modulation signal and generate the drive weak electrical signal; The power conversion module, connected to the drive module, is used to convert power according to the weak drive signal to generate alternating current. The filtering module, connected to the power conversion module, is used to filter out high-frequency harmonics in AC power and feed electrical energy into the power grid.

[0026] Photovoltaic power generation devices and battery energy storage are connected to grid-connected inverters (main topology as follows) Figure 3The new generation of power electronic switching devices (SiC-MOSFETs) shown provide DC voltage with an efficiency exceeding 98%. A sampling module (using the AD7656 sampling chip) monitors the DC input voltage and current in real time, converting the collected signals into electrical signals for processing. After filtering and amplification, these signals are sent to the DC grid inverter control module (main control chip is TMS28347). The sampling module detects the grid voltage and current, feeding this information back to the control module, which uses an improved virtual synchronous generator based on active disturbance rejection (ADD). The module calculates active and reactive power and uses this ADD-based virtual synchronous generator to control the frequency and phase of the output grid for synchronization control. Based on the sampling and synchronization control information, the control module runs an SPWM modulation algorithm to generate a modulation signal for controlling the switching transistors' on / off states. The drive circuit receives the modulation signal and generates a weak electrical signal. The filtering module further filters out high-frequency harmonics. The sampling module samples the inverter's output voltage, current, and grid status in real time and feeds this information back to the control module. The control module of the grid-connected inverter controls the inverter based on feedback signals, using a dual closed-loop control algorithm of voltage and current to ensure that the inverter output is synchronized with the grid, while maintaining power quality within the specified range.

[0027] The DC network ship control block diagram based on the self-disturbance rejection virtual synchronous generator is as follows: Figure 4 As shown. Specifically, a portion of the system is modeled: The DC bus voltage is established and controlled by a bidirectional DC / DC converter, outputting the control results of the outer voltage loop and inner current loop. The space state equation of the bidirectional DC / DC converter is expressed as follows: , in, For inductor current, The voltage of the energy storage element. For the converter output current, This is the output voltage of the converter. This is the parasitic resistance of the inductor. For switching transistors duty cycle, for Duty cycle.

[0028] The outer voltage loop uses the DC bus voltage as the control object, and generates the inner current loop reference value through a PI regulator. The expression is: , in, This is the reference value for bus voltage. K pv , K ivThese are the proportional and integral coefficients of the voltage outer loop PI regulator, respectively. This is the actual value of the bus voltage.

[0029] The inner current loop controls the battery current and generates a duty cycle control signal through a regulator. The expression is: , in, This is the actual value of the battery current. This is the reference value for the current output from the outer voltage loop. K pi , K ii These are the proportional and integral coefficients of the current inner loop PI regulator, respectively.

[0030] The adaptive steps for the gain coefficients of the extended state observer in S2 include: Based on the input and output data of the control module, the state equation is: , in, This is the vector of parameters to be tuned for linear active disturbance rejection control. x k To measure the input signal for linear active disturbance rejection control, x k+1 For output signal; The maximum Lyapunov exponent, which characterizes the stability of the system, is estimated in real time using the recursive least squares method. The expression is as follows: , in, This represents the matrix norm of the Jacobian determinant of the input signal and the closed-loop state equation. v k This indicates a small perturbation at the input signal; When the maximum Lyapunov exponent exceeds the preset instability threshold, the parameter adjustment mechanism is triggered; The adjustment amount of the gain coefficient of the extended state observer is calculated using the gradient descent method, and the gain coefficient is updated based on this adjustment amount. The expression for the gradient calculation is as follows: , According to the gradient descent method, the adjustment value of the parameter to be adjusted is obtained from the gradient pairs: , in, The learning rate is used to control the step size of each iteration update; In addition, the adjustment value must meet the parameter update rate: , in, β is the gain coefficient of the extended state observer in the active disturbance rejection controller, and sat is the saturation function to prevent parameter abrupt changes.

[0031] The virtual synchronous generator model in S2 includes calculating the angular frequency and phase angle of the virtual synchronous generator, expressed as follows: , in, J For rotational inertia, ω The angular frequency of the virtual synchronous generator. ω 0 is the rated angular frequency. For reference active power, p 0 The input active power is calculated based on the voltage and current signals from the grid side. The damping coefficient is... The output phase angle of the virtual synchronous generator.

[0032] Angular frequency based on virtual synchronous generator ω With the rated angular frequency ω The difference of 0 is used to adjust the input active power value to obtain the original active power command. The expression is: , Reference reactive power based on virtual synchronous generator With input reactive power The difference is used to adjust the amplitude of the AC voltage output of the inverter of the virtual synchronous generator. The expression is: , in, and To adjust the parameters.

[0033] The expression for input active power is: The expression for input reactive power is: ,in, , and For the three-phase voltage on the AC side, , and This refers to the three-phase current on the AC side.

[0034] Linear Active Disturbance Rejection Control (LADRC) is introduced into the active power-droop control loop of the virtual co-operation control system as an outer-loop frequency controller to regulate the energy storage output. The LADRC schematic diagram is shown below. Figure 5 As shown, the angular velocity deviation of the synchronizer is used as the input signal for the LADRC damping controller. The active disturbance rejection control model is established as follows: , in, The filter factor; This is for simulating step size; It is a velocity factor, used only to suppress severe overshoot in the early stages of the system; This is an error signal; This is the optimal control synthesis function. In the active disturbance rejection control model, it is obtained through the target value. Achieve a fast, overshoot-free transition process And obtain its differential signal. .

[0035] The control synthesis function The goal is to arrange a transition process from the current state to the target state in a fast, overshoot-free manner, expressed as: , in, To control the linearity of the synthesis function, To control the internal variables of the synthesis function; It is a symbolic function; State variables The offset observations of the extended state observer constructed based on linear active disturbance rejection control technology in S2 include a first offset observation, a second offset observation, and a third offset observation, where the third offset observation is the total disturbance observation, expressed as: , , , in, , and These are the first offset observation, the second offset observation, and the third offset observation, respectively. h This is for simulating step size; , and The observer gain coefficient; The dynamics of the controlled object are known; and Both are nonlinear functions relating to the deviation of the angular frequency from the rated angular frequency; k For time indexing; This represents the deviation of the angular frequency from the rated angular frequency. The gain coefficient of the control quantity; For the first k One control cycle.

[0036] The expression for the nonlinear function of the deviation is: ,in, For output signal Compared with the first offset observation value The difference, For exponential parameters, The length is the linear interval. This is determined by the input signal to the controlled object. and output signal Estimate the first and second offset observations, record the errors between the inter-regional synchronous generator power angle deviation reference value and the first offset observation value, and the errors between the inter-regional synchronous generator speed deviation reference value and the second offset observation value, to obtain the initial control quantity of the linear active disturbance rejection frequency controller. Based on the initial control quantity and the total disturbance observation value, obtain the control quantity, i.e., feedforward compensation fusion. The specific process is as follows: Subtract the total disturbance observation value scaled by the compensation factor from the original active power command to generate the disturbance-resistant active power reference command, expressed as: , in, Active power reference command, For the total disturbance observations, This is a compensation factor.

[0037] In S6, the specific steps for obtaining the input value of the quasi-proportional resonant controller include: Based on the system output voltage amplitude command and phase angle generated by the virtual synchronous generator control, a three-phase symmetrical reference voltage signal is synthesized. The three-phase reference voltage signal is compared with the sampled actual output three-phase voltage signal of the inverter, and the deviation signal is used as the input of the voltage outer loop. The output of the voltage outer loop is used as the reference signal of the current inner loop. The current inner loop reference signal is compared with the sampled actual output current signal of the inverter to obtain the current tracking error signal. The current tracking error signal is input to the quasi-proportional resonant controller.

[0038] Specifically, the control module calls the three-phase voltage synthesis algorithm stored in the memory, based on the system output voltage amplitude command calculated in real time by the virtual synchronous generator control loop. With phase angle θ The expression for synthesizing a three-phase symmetrical reference voltage signal is: , in, , and This refers to the three-phase voltage on the AC side.

[0039] The sampling module acquires the actual three-phase voltage signal output by the inverter in real time using the AD7656 chip, compares it with the reference three-phase voltage signal generated in the control module, and uses the resulting voltage deviation signal as the input to the outer voltage loop. The output of the outer voltage loop is used as the reference signal for the inner current loop. Simultaneously, the sampling module acquires the actual output current signal of the inverter, and the control module performs current tracking error calculation, inputting the current tracking error signal to the quasi-proportional resonant controller.

[0040] The transfer function of the quasi-proportional resonant controller is, based on proportional control, superimposed with resonant control of a specified width at the fundamental frequency of the power grid, and its expression is: , in, K p This is the proportionality coefficient. K i The integral coefficient is... ω s This is the cutoff frequency of the low-pass filter. ω 1 represents the fundamental angular frequency of the power grid. The quasi-proportional resonant controller is implemented through discretization, and its resonant frequency is set to the fundamental frequency of the power grid. It can provide high gain at the fundamental frequency and achieve zero steady-state error tracking of the fundamental sinusoidal current signal. The control block diagram of the quasi-PR control is shown below. Figure 6 As shown.

[0041] Based on the ship's DC grid system, the closed-loop transfer function of the inner current loop. for: , in, This is the proportionality coefficient of the current loop. For converter gain, L For filtering inductors, C This is a filter capacitor.

[0042] The damping coefficient of the inner current loop is obtained as follows: , By setting the damping coefficient =0.707, calculate the current loop proportionality coefficient. The optimal value is found to ensure that the system has both fast response and good stability.

[0043] Based on the system's main circuit topology, a transfer function model for the voltage control outer loop is established. The output of the voltage outer loop controller... With reference input and load current disturbance The relationship between them is described by the following formula: , intermediate variables in the formula , , , , and They are respectively: , , in, C is the filter inductor, C is the filter capacitor, and R is the equivalent parasitic resistance. For converter gain, , and System angular frequency related quantities This refers to the proportional gain of the outer voltage loop, which is the proportional gain of the voltage loop controller itself. This is a reference instruction used to convert the output of other controllers into the current inner loop. To provide the differential coefficients for phase lead, The proportional gain factor of the inner loop controller. This is the total proportional gain of the forward path from the voltage controller output to the inverter bridge output. The composite gain in the controller related to derivative or lead compensation. This refers to the main composite gain related to proportional control in the controller. , and The coefficient function of the characteristic polynomial.

[0044] Thus, the closed-loop transfer function of the outer voltage loop is obtained, and its expression is: .

[0045] The Routh stability criterion is used to determine the stability of the system. The necessary and sufficient condition for system stability is that all elements in the first column of the Routh table are stable. Since it is positive, we can establish the following system of inequalities: .

[0046] The disturbance rejection control method for ship-to-shore power grid connection also includes a DC bus voltage stabilization step: The bidirectional DC / DC converter employs a dual-loop control structure consisting of an outer voltage loop and an inner battery current loop. The DC bus voltage is the controlled object, and a reference value for the inner current loop is generated by a PI regulator. The battery current is then the controlled object, and a duty cycle control signal is generated by a PI regulator to maintain the stability of the DC bus voltage.

[0047] The method and system of this embodiment were simulated, and a shipboard DC grid power supply system using only virtual synchronous generator control was also simulated. The operating conditions were set as follows: 5000W load connected in 0.2s, grid connection in 0.5s, and operation for 0.5s. The simulation results of the two scenarios were compared. Figure 7 , Figure 8 , Figure 9 and Figure 10 As shown in the figure, the phase tracking of the improved DC ship power supply system based on active disturbance rejection control and the oscillation of the grid-side voltage result both reach stability at 0.05s. Figure 7 The phase tracking results of the DC ship power supply system based on virtual synchronous generator control are shown in the figure. The red line represents the phase of the power grid, and the blue line represents the tracking phase of the output based on the virtual synchronous generator control. Figure 8 The image shows the phase tracking results for DC grid-connected ship control based on an active disturbance rejection virtual synchronous generator (ADRG). The red line represents the grid phase, and the blue line represents the tracking phase output from the ADRG. It can be observed that... Figure 7 The phase diagram of the central power grid and the phase diagram of the traditional virtual synchronous generator control output become mismatched over time. Figure 8 The phase of the power grid and the phase of the virtual pedestal generator control output based on active disturbance rejection gradually match over time. Figure 8 The grid voltage waveforms are the output voltages under two control strategies. It can be observed that... Figure 9 The voltage of the power grid and the output voltage of the traditional virtual synchronous generator control system exhibit a voltage mismatch over time. The red line represents the grid voltage, and the blue line represents the voltage waveform output from the grid side of the DC ship power supply system based on virtual synchronous generator control. Figure 10 The voltage of the power grid and the voltage output of the virtual synchronizing generator based on active disturbance rejection gradually match over time. The red line represents the grid voltage, and the blue line represents the voltage waveform output from the DC-connected ship control network based on the virtual synchronous generator. Figure 7 , Figure 8 , Figure 9 and Figure 10 The comparison shows that the DC grid-connected ship control system based on the self-disturbance rejection virtual synchronous generator is superior to the ship DC grid-connected power supply system that only uses virtual synchronous generator control.

[0048] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the described module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0049] The electronic device of this invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) or loaded from a storage unit into random access memory (RAM). The RAM may also store various programs and data required for device operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0050] Multiple components in the device are connected to an I / O interface, including: input units such as a keyboard, mouse, etc.; output units such as various types of displays, speakers, etc.; storage units such as disks, optical disks, etc.; and communication units such as network interface cards, modems, wireless transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks. The processing unit performs the various methods and processes described above, such as the method of the present invention. For example, in some embodiments, the method of the present invention may be implemented as a computer software program tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via ROM and / or the communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of the method of the present invention described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute the method of the present invention by any other suitable means (e.g., by means of firmware).

[0051] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SoCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0052] The program code used to implement the methods of the present invention can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0053] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A disturbance-resistant control method for DC grid-connected new energy ship shore power grid connection, characterized in that, The specific steps include: S1. The sampling module collects the input voltage and current signals from the DC side and the voltage and current signals from the grid side in real time, and converts them into electrical signals that can be processed by the control module. S2. A virtual synchronous generator model is constructed based on the rotor motion equation of the synchronous generator. The angular frequency and phase angle of the virtual synchronous generator are calculated according to the voltage and current signals of the grid side. The deviation between the angular frequency and the rated angular frequency is input to the extended state observer constructed based on linear active disturbance rejection control technology to estimate and output the total disturbance observation value in real time. S3. Calculate the original active power command of the virtual synchronous generator model and perform feedforward compensation fusion with the total disturbance observation to generate the disturbance-resistant active power reference command. S4. Based on the converted DC-side signal in S1 and the active power reference command in S3, run the SPWM modulation algorithm to generate a modulation signal, and use the modulation signal to control the operation of the switching transistor in the power conversion module. S5. The modulation signal is amplified by the driving module, which drives the power conversion module to generate AC power, and the high-frequency harmonics are filtered out by the filtering module before being fed to the power grid. S6. The sampling module collects the inverter output current filtered in S5 in real time and compares it with the reference current signal synthesized from the phase angle and rated voltage generated by S2. The quasi-proportional resonant controller is used to perform zero steady-state error tracking of the error signal to generate a current compensation signal for real-time correction of the modulation signal.

2. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 1, characterized in that, The adaptive step for the gain coefficient of the extended state observer in S2 includes: Based on the input and output data of the control module, the maximum Lyapunov exponent, which characterizes the stability of the system, is estimated in real time using the recursive least squares method. When the maximum Lyapunov exponent is greater than the preset instability threshold, the parameter adjustment mechanism is triggered; The adjustment amount of the gain coefficient of the extended state observer is calculated using the gradient descent method, and the gain coefficient is updated based on the adjustment amount.

3. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 1, characterized in that, The virtual synchronous generator model in S2 includes calculating the angular frequency and phase angle of the virtual synchronous generator, expressed as follows: ， in, J For rotational inertia, ω The angular frequency of the virtual synchronous generator. ω 0 is the rated angular frequency. For reference active power, p 0 The input active power is calculated based on the voltage and current signals from the power grid side. The damping coefficient is... The output phase angle of the virtual synchronous generator.

4. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 3, characterized in that, The virtual synchronous generator model also includes adjusting the value of the virtual input active power based on the difference between the angular frequency of the virtual synchronous generator and the rated angular frequency; and adjusting the amplitude of the AC voltage expected to be output by the inverter of the virtual synchronous generator based on the difference between the reference reactive power and the input reactive power of the virtual synchronous generator.

5. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 1, characterized in that, The extended state observer in S2, constructed based on linear active disturbance rejection control (ADR) technology, calculates the offset observation value based on the deviation between the angular frequency and the rated angular frequency. The offset observation value includes a first offset observation value, a second offset observation value, and a third offset observation value, where the third offset observation value is the total disturbance observation value, expressed as: ， ， ， in, , and These are the first offset observation, the second offset observation, and the third offset observation, respectively. h This is for simulating step size; , and The observer gain coefficient; The dynamics of the controlled object are known; and Both are nonlinear functions relating to the deviation of the angular frequency from the rated angular frequency; k For time indexing; This represents the deviation of the angular frequency from the rated angular frequency. The gain coefficient of the control quantity; For the first k One control cycle.

6. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 1, characterized in that, In S3, the specific process of feedforward compensation fusion is as follows: subtract the total disturbance observation value scaled by the compensation factor from the original active power command to generate the disturbance-resistant active power reference command.

7. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 1, characterized in that, In step S6, the specific steps for obtaining the input value of the quasi-proportional resonant controller include: Based on the system output voltage amplitude command and phase angle generated by the virtual synchronous generator control, a three-phase symmetrical reference voltage signal is synthesized. The three-phase reference voltage signal is compared with the sampled actual output three-phase voltage signal of the inverter, and the deviation signal is used as the input of the voltage outer loop. The output of the voltage outer loop is used as the reference signal of the current inner loop. The current inner loop reference signal is compared with the sampled actual output current signal of the inverter to obtain the current tracking error signal. The current tracking error signal is input to the quasi-proportional resonant controller.

8. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 7, characterized in that, The transfer function of the quasi-proportional resonant controller is, based on proportional control, a resonant control with a specified width at the fundamental frequency of the power grid is superimposed, and its expression is: ， in, K p This is the proportionality coefficient. K i The integral coefficient is... ω s This is the cutoff frequency of the low-pass filter. ω 1 represents the fundamental angular frequency of the power grid.

9. The anti-disturbance control method for DC grid-connected new energy ship shore power grid connection according to claim 1, characterized in that, The method further includes a DC bus voltage stabilization step: The bidirectional DC / DC converter employs a dual-loop control structure consisting of an outer voltage loop and an inner battery current loop. The DC bus voltage is the controlled object, and a reference value for the inner current loop is generated by a PI regulator. The battery current is then the controlled object, and a duty cycle control signal is generated by a PI regulator to maintain the stability of the DC bus voltage.

10. A disturbance rejection control system for DC grid-connected new energy ship shore power grid connection, used in the disturbance rejection control method for DC grid-connected new energy ship shore power grid connection as described in any one of claims 1 to 9, characterized in that, The system includes: a sampling module, a control module, a drive module, a power conversion module, and a filtering module; The sampling module is used to acquire voltage and current signals from the DC side and the grid side in real time, and to perform signal conversion and processing. The control module is connected to the sampling module and is used to calculate the angular frequency and phase angle based on the virtual synchronous generator model; run the extended state observer to estimate the total system disturbance in real time; perform feedforward compensation fusion to generate the disturbance-resistant active power reference command; run the SPWM modulation algorithm to generate the modulation signal; and execute the current tracking algorithm based on quasi-proportional resonance control to generate the current compensation signal. The drive module is connected to the control module and is used to receive the modulation signal and generate a weak drive signal; A power conversion module, connected to the drive module, is used to perform power conversion based on the drive weak current signal to generate alternating current. The filtering module, connected to the power conversion module, is used to filter out high-frequency harmonics in the AC power and feed electrical energy into the power grid.

Images