Anti-disturbance control method and system for dc networking of new energy ship shore power grid connection

Abstract

The present application relates to a kind of new energy ship shore power grid connection anti-disturbance control method and system of direct current networking, based on virtual synchronous generator model calculation angle frequency and phase angle, total disturbance is input into extended state observer real-time estimation angle frequency deviation;The original active instruction of virtual synchronous generator is fused with total disturbance observation value and fed forward compensation, generates active power reference instruction of anti-disturbance;According to direct current side signal and active instruction, SPWM modulation is operated, and modulation signal control power conversion is generated;Drive signal is amplified after filtering and is fed to grid;While gathering output current, compare with the reference current synthesized by phase angle, realize static error tracking using proportional resonant controller, generate compensation signal and modify modulation in real time;New generation power electronic switching device SiC-MOSFET is used in grid-connected power converter, and efficiency can be more than 98%.Compared with prior art, the present application has the advantages of high stability, high power quality and strong reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-grid, in particular to a new energy ship DC networking shore power grid connection anti-disturbance control method and system. BACKGROUND

[0002] When the DC networking new energy ship docks, the distributed power carried by the ship 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 main grid, but also brings a series of challenges to the stable operation of the ship's DC networking power supply system itself.

[0003] The distributed energy sources used by new energy ships, such as photovoltaic power generation, have the characteristics of instability, intermittency and low inertia. These characteristics make the ship prone to interfere with the safe operation of the shore power main grid during grid connection, and also affect the stability of the ship's DC networking power supply system itself. Therefore, the control strategy research for the ship's DC networking power supply system is particularly important. In the prior art, the virtual synchronous generator control strategy is widely used, which can improve the system inertia to a certain extent and reduce the impact on the main grid.

[0004] However, in actual application, the existing control method still has the problem of insufficient adaptability of active power control, especially in the grid connection moment, which is greatly impacted, resulting in a long time required for the system to reach stable operation. In addition, in the DC networking system, the establishment of stable DC bus voltage also faces difficulties, and the control strategy needs to be further optimized. When the ship's operating condition changes suddenly, the system with fixed control parameters is prone to oscillation, affecting the power supply quality and system reliability.

[0005] At present, the research on DC networking new energy ships connecting to shore power mainly focuses on energy management during docking. In contrast, the research on the impact of ship connection to the main grid and the stability of the ship's DC networking system is still in urgent need of application. The existing related technical solutions mainly focus on efficient energy distribution and improving the operation efficiency of the ship's power grid, but there are still deficiencies in dealing with grid connection impact, improving system stability and dynamic response performance. Therefore, how to effectively improve the inertia support capability of the new energy ship's DC networking power supply system and reduce the impact of the grid connection process on the ship's DC networking system and the shore power main grid is a technical problem to be solved. SUMMARY

[0006] The purpose of the present application is to overcome the defects of the prior art, and provide a new energy ship shore power grid connection anti-disturbance control method and system, which introduces active disturbance rejection control into the power outer ring of the virtual synchronous generator, constructs an extended state observer that can estimate and compensate the total disturbance of the system in real time, effectively deals with the power grid impact at the moment of ship shore power grid connection, and improves the inertia support capability and anti-disturbance performance of the system.

[0007] The purpose of the present application can be realized by the following technical solutions:

[0008] According to one aspect of the present application, a ship shore power grid connection anti-disturbance control method is provided, and the specific steps include:

[0009] S1, real-time acquisition of input voltage and current signals of the DC side, and voltage and current signals of the grid side is realized through a sampling module, and the signals are converted into electrical signals that can be processed by a control module;

[0010] S2, based on the virtual synchronous generator model 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 of the angular frequency from the rated angular frequency is input into the extended state observer constructed based on the linear active disturbance rejection control technology, and the total disturbance observation value is estimated and output in real time;

[0011] S3, the original active power instruction of the virtual synchronous generator model is calculated, and the total disturbance observation value is fed forward and compensated to generate an active power reference instruction after disturbance rejection;

[0012] S4, according to the converted DC side signal in S1 and the active power reference instruction in S3, an SPWM modulation algorithm is run to generate a modulation signal, and the modulation signal is used to control the action of the switch tube in the power conversion module;

[0013] S5, the modulation signal is amplified through a driving module to drive the power conversion module to generate alternating current, and the high-frequency harmonics are filtered out through a filtering module to feed the grid;

[0014] S6, the sampling module real-time acquires the filtered inverter output current in S5, and compares it with the reference current signal composed of the phase angle and rated voltage generated by S2, and uses a proportional resonant controller to track the error signal without static error to generate a current compensation signal for real-time correction of the modulation signal.

[0015] Further, the adaptive step of the gain coefficient of the extended state observer in S2 includes:

[0016] Based on the input and output data of the control module, the maximum Lyapunov index representing system stability is estimated in real time by using recursive least square method;

[0017] When the maximum Lyapunov index is greater than a preset instability threshold, a parameter adjustment mechanism is triggered;

[0018] The adjustment amount of the extended state observer gain coefficient is calculated by gradient descent method, and the gain coefficient is updated according to the adjustment amount.

[0019] Further, the virtual synchronous generator model in S2 includes calculating the angular frequency and phase angle of the virtual synchronous generator, and the expression is:

[0020] ,

[0021] wherein, J is the moment of inertia, ω is the angular frequency of the virtual synchronous generator, ω 0 is the rated angular frequency, is the reference active power, P 0 is the input active power, is the damping coefficient, is the output phase angle of the virtual synchronous generator.

[0022] Further, the virtual synchronous generator model further includes adjusting the value of the virtual input active power according to the difference between the angular frequency of the virtual synchronous generator and the rated angular frequency; adjusting the amplitude of the alternating voltage of the inverter expected output of the virtual synchronous generator according to the difference between the reference reactive power of the virtual synchronous generator and the input reactive power.

[0023] Further, the extended state observer based on linear active disturbance rejection control technology in S2 calculates the offset amount observation value according to the deviation of the angular frequency and the rated angular frequency, and the offset amount observation value includes a first offset amount observation value, a second offset amount observation value and a third offset amount observation value, wherein the third offset amount observation value is a total disturbance observation value, and the expression is:

[0024] ,

[0025] ,

[0026] ,

[0027] wherein, , and are the first offset amount observation value, the second offset amount observation value and the third offset amount observation value, respectively; h is the simulation step length; , and is an observer gain coefficient; is a known dynamic of the controlled object; and are both nonlinear functions of the deviation of the angular frequency from the rated angular frequency; k is a time index; is the deviation of the angular frequency from the rated angular frequency; is a gain coefficient of the control quantity; is the first k control cycle.

[0028] Further, in the S3, the specific process of the feedforward compensation fusion is: subtracting the total disturbance observation value scaled by the compensation factor from the original active power instruction to generate the anti-disturbance active power reference instruction.

[0029] Further, in the S6, the specific steps of obtaining the input value of the quasi-proportional-resonant controller include:

[0030] Based on the system output voltage amplitude instruction 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 a current tracking error signal; the current tracking error signal is input to the quasi-proportional-resonant controller.

[0031] Further, the transfer function of the quasi-proportional-resonant controller is: on the basis of proportional control, a resonant control with a specified width at the grid fundamental frequency is superimposed, and the expression is:

[0032] ,

[0033] wherein, K p is a proportional coefficient, K i is an integral coefficient, ω s is a cutoff frequency of a low-pass filter, ω 1 is the grid fundamental angular frequency.

[0034] Further, the method further includes a direct current bus voltage stabilization step:

[0035] Through the bidirectional DC / DC converter, a double-loop control structure of voltage outer loop and battery current inner loop is adopted, the DC bus voltage is taken as the control object, the current inner loop reference value is generated through the PI regulator, and then the battery current is taken as the control object, the duty control signal is generated through the PI regulator, so that the stability of the DC bus voltage is maintained.

[0036] According to another aspect of the present application, a ship shore power grid-connected anti-disturbance control system is provided, the system comprising: a sampling module, a control module, a driving module, a power conversion module and a filtering module;

[0037] The sampling module is used to collect voltage and current signals of the DC side and the grid side in real time, and to perform signal conversion and processing.

[0038] The control module is connected with the sampling module, and is used to calculate the angular frequency and the phase angle based on a virtual synchronous generator model, to run an extended state observer to estimate the total disturbance of the system in real time, to perform feedforward compensation fusion to generate an active power reference instruction after anti-disturbance, to run an SPWM modulation algorithm to generate a modulation signal, and to perform a current tracking algorithm based on a quasi-proportional resonant control to generate a current compensation signal.

[0039] The driving module is connected with the control module, and is used to receive the modulation signal and generate a driving weak electric signal.

[0040] The power conversion module is connected with the driving module, and is used to perform power conversion according to the driving weak electric signal to generate alternating current.

[0041] The filtering module is connected with the power conversion module, and is used to filter out high-frequency harmonics in the alternating current and feed the electric energy into the grid.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] (1) Improve the system inertia support and anti-disturbance ability: 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 the total disturbance in real time, effectively enhance the inertia support ability of the ship DC grid power supply system, improve the anti-disturbance performance of the system in the grid impact moment, and overcome the defects of poor adaptability of the traditional virtual synchronous generator active control.

[0044] (2) Realize fast and stable and dynamic performance optimization: the active disturbance rejection control technology and the virtual synchronous generator control are deeply fused, the influence of internal and external disturbances is actively offset through the feedforward compensation mechanism, so that the system can quickly recover to stable state when subjected to grid impact or load mutation, the time required for the system to reach stable operation state is shortened, and the dynamic response performance under strong coupling and multi-source disturbance is improved.

[0045] (3) Ensure the sustained stability of the control system: adopt the anti-disturbance parameter self-tuning method based on Lyapunov index, estimate the maximum Lyapunov index of the system in real time and dynamically adjust the observer gain coefficient, to ensure that the control system always remains stable under different working conditions, solve the problem of system oscillation caused by fixed control parameters when the working condition of the ship changes, and improve the adaptability and reliability of the system.

[0046] (4) Improve the power quality and harmonic suppression effect: adopt the quasi-proportional resonant control technology in the double closed-loop control, superimpose the resonant control at the fundamental frequency of the power grid on the basis of proportional control, realize the zero-error tracking of the alternating current signal, avoid the power coupling defect in the traditional dq coordinate system, and still maintain good control effect under nonlinear load conditions, to ensure that the harmonic distortion rate is maintained within the standard range.

[0047] (5) Enhance the overall operation reliability of the system: through the voltage support function of the energy storage unit in the DC networking structure, combined with the double-loop control of the voltage outer ring and the current inner ring of the bidirectional DC / DC converter, realize the precise and stable control of the DC bus voltage, effectively reduce the intermittent influence of photovoltaic power generation modules, and protect the stability of the DC bus voltage, thereby improving the operation reliability of the entire ship DC networking power supply system. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Flow chart of anti-disturbance control method for DC networking new energy ship shore power grid connection;

[0049] Figure 2 DC networking structure diagram of new energy ship;

[0050] Figure 3 SiC-MOSFET converter topology for DC networking new energy ship shore power grid connection;

[0051] Figure 4 Control block diagram of DC networking ship based on active disturbance rejection virtual synchronous generator;

[0052] Figure 5 Principle diagram of active disturbance rejection control;

[0053] Figure 6 Control block diagram of quasi-PR control;

[0054] Figure 7 Phase tracking result of DC ship power supply system based on virtual synchronous generator control;

[0055] Figure 8 Phase tracking result of DC networking ship based on active disturbance rejection virtual synchronous generator control;

[0056] Figure 9 The grid-side voltage results are for a DC ship power supply system based on virtual synchronous generator control.

[0057] 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

[0058] 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.

[0059] 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:

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] A ship shore power grid connection anti-disturbance control system using the method, as shown in Figure 2 includes: a sampling module, a control module, a driving module, a power conversion module and a filtering module.

[0067] The sampling module is used to collect the voltage and current signals of the DC side and the grid side in real time, and to perform signal conversion and processing.

[0068] The control module is connected with the sampling module, and is used to calculate the angular frequency and phase angle based on the virtual synchronous generator model; to run the extended state observer to estimate the total disturbance of the system in real time; to perform feedforward compensation fusion to generate the active power reference instruction after disturbance; to run the SPWM modulation algorithm to generate the modulation signal; and to perform the current tracking algorithm based on the quasi-proportional resonant control to generate the current compensation signal.

[0069] The driving module is connected with the control module, and is used to receive the modulation signal and generate the driving weak electric signal.

[0070] The power conversion module is connected with the driving module, and is used to perform power conversion according to the driving weak electric signal to generate alternating current.

[0071] The filtering module is connected with the power conversion module, and is used to filter out the high-frequency harmonics in the alternating current and feed the electric energy into the grid.

[0072] The photovoltaic power generation device and the battery energy storage provide direct current voltage for the grid-connected inverter (the main topology is a new generation of power electronic switching device SiC-MOSFET as shown in Figure 3 The efficiency can exceed 98%. The sampling module (the sampling chip is AD7656) is used to monitor the input voltage and current of the DC side in real time, and the collected signals are converted into electric signals processed by the module, and are sent to the DC grid inverter control module (the main control chip is TMS28347) after filtering, amplification and other processing. The sampling module is used to detect the voltage and current of the grid, and feedback to the control module based on the improved active disturbance rejection virtual generator, to calculate the active power and reactive power, and to use the output frequency and phase of the active disturbance rejection virtual synchronous generator control to synchronize control. The control module runs the SPWM modulation algorithm according to the sampling information and synchronization control information to generate the modulation signal for controlling the conduction and cutoff of the switching tube. The driving circuit receives the modulation signal and generates the weak electric signal. The filtering module further filters out the high-frequency harmonics. The sampling module is used to sample the output voltage, current and grid state of the inverter in real time, and feeds back these information to the control module. The control module of the grid-connected inverter controls according to the feedback signal, uses the voltage and current double closed loop control algorithm to ensure that the inverter output is synchronized with the grid, and maintains the power quality within the specified range.

[0073] The control block diagram of the DC grid ship based on the active disturbance rejection virtual synchronous generator is as followsFigure 4 Part of the system is modeled, as shown in the figure. Specifically, the part of the system is modeled:

[0074] The DC bus voltage is established, and the control results of the voltage outer loop and the current inner loop are controlled by the bidirectional DC / DC converter. The expression of the space state equation of the bidirectional DC / DC converter is:

[0075] ,

[0076] Where, is the inductor current, is the voltage of the energy storage element, is the converter output current, is the converter output voltage, is the inductor parasitic resistance. is the duty cycle of the switch tube is the duty cycle of

[0077] The voltage outer loop takes the DC bus voltage as the control object, and generates the current inner loop reference value through the PI regulator, and the expression is:

[0078] ,

[0079] Where, is the bus voltage reference value, K pv , K iv are the proportional coefficient and integral coefficient of the voltage outer loop PI regulator respectively, is the actual value of the bus voltage.

[0080] The current inner loop takes the battery current as the control object, and generates the duty cycle control signal through the regulator, and the expression is:

[0081] ,

[0082] Where, is the actual value of the battery current, is the current reference value output by the voltage outer loop, K pi , K ii are the proportional coefficient and integral coefficient of the current inner loop PI regulator respectively.

[0083] The adaptive step of the gain coefficient of the extended state observer in S2 includes:

[0084] ​​Based on the input and output data of the control module, the state equation is:

[0085] ,

[0086] wherein, is a linear active disturbance rejection control parameter to be adjusted vector, x k is a measured input linear active disturbance rejection control signal, x k+1 is an output signal;

[0087] The maximum Lyapunov index representing the stability of the system is estimated in real time by using the recursive least square method, and the expression is:

[0088] ,

[0089] wherein, represents the matrix norm of the Jacobian matrix of the input signal and the closed-loop state equation, v k represents a small perturbation at the input signal;

[0090] When the maximum Lyapunov index is greater than the preset instability threshold, the parameter adjustment mechanism is triggered;

[0091] The adjustment amount of the extended state observer gain coefficient is calculated by the gradient descent method, and the gain coefficient is updated according to the adjustment amount, and the expression of the gradient calculation is:

[0092] ,

[0093] According to the gradient descent method, the adjustment value of the parameter to be adjusted is solved from the gradient:

[0094] ,

[0095] wherein, is a learning rate used to control the step size of each iteration update;

[0096] In addition, the adjustment value needs to satisfy the parameter update rate:

[0097] ,

[0098] wherein, β is the gain coefficient of the extended state observer in the active disturbance rejection controller, and sat is a saturation function to prevent parameter mutation.

[0099] The virtual synchronous generator model in S2 includes calculating the angular frequency and phase angle of the virtual synchronous generator, and the expression is:

[0100] ,

[0101] wherein, J J is the moment of inertia, ω ω is the angular frequency of the virtual synchronous generator, ω 0 is the rated angular frequency, P is the reference active power, p 0 P is the input active power calculated from the grid-side voltage and current signals, K is the damping coefficient, θ is the phase angle of the virtual synchronous generator output.

[0102] Based on the angular frequency of the virtual synchronous generator ω and the difference between the rated angular frequency ω 0, the value of the input active power is adjusted to obtain the original active power instruction , the expression is:

[0103] ,

[0104] Based on the reference reactive power of the virtual synchronous generator and the difference between the input reactive power , the amplitude of the alternating voltage of the inverter expected output of the virtual synchronous generator is adjusted , the expression is:

[0105] ,

[0106] wherein, and are adjustment parameters.

[0107] The expression of the input active power is: , the expression of the input reactive power is: wherein, , and are three-phase voltages on the alternating side, , and are three-phase currents on the alternating side.

[0108] The linear active disturbance rejection control technology (LADRC) is introduced into the active-droop control link of the virtual synchronous control, which is used as the outer ring frequency controller of the active control to adjust the energy storage output. The active disturbance rejection control principle diagram is shown in Figure 5 , and the angular velocity deviation of the synchronous machine is used as the input signal of the LADRC damping controller. The active disturbance rejection control model is established as:

[0109] ,

[0110] wherein, is a filter factor; is a simulation step; is a speed factor, only used to suppress severe overshoot in the initial stage of the system; is an error signal; is an optimal control synthesis function. In the active disturbance rejection control model, the target value achieves a fast and overshoot-free transition process , and obtains the differential signal .

[0111] wherein the control synthesis function is to arrange a transition process from the current state to the target state in a fast and overshoot-free manner, and its expression is:

[0112] ,

[0113] wherein, is the linearity of the control synthesis function, is the internal variable of the control synthesis function; is a sign function; is a state variable

[0114] The offset observation value of the extended state observer based on the linear active disturbance rejection control technology in S2 includes a first offset observation value, a second offset observation value and a third offset observation value, wherein the third offset observation value is a total disturbance observation value, and its expression is:

[0115] ,

[0116] ,

[0117] ,

[0118] wherein, , and are the first offset observation value, the second offset observation value and the third offset observation value, respectively; h is a simulation step; , and are observer gain coefficients; is a known dynamic of the controlled object; and are both nonlinear functions of the deviation of the angular frequency from the rated angular frequency; k is a time index; is 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.

[0119] 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:

[0120] ,

[0121] in, Active power reference command, For the total disturbance observations, This is a compensation factor.

[0122] In S6, the specific steps for obtaining the input value of the quasi-proportional resonant controller include:

[0123] 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.

[0124] 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:

[0125] ,

[0126] wherein, , and is the three-phase voltage on the AC side.

[0127] The sampling module collects the three-phase voltage signals actually output by the inverter in real time through the AD7656 chip, compares the reference three-phase voltage signals generated in the control module, and generates a voltage deviation signal 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, and the sampling module simultaneously collects the actual output current signals of the inverter. The control module performs current tracking error calculation and inputs the current tracking error signal to the quasi-proportional-resonant controller.

[0128] The transfer function of the quasi-proportional-resonant controller is, on the basis of proportional control, superimposed with a specified width of resonant control at the grid fundamental frequency, and the expression is:

[0129] ,

[0130] wherein, K p is the proportional coefficient, K i is the integral coefficient, ω s is the cutoff frequency of the low-pass filter, ω 1 is the grid fundamental angular frequency. The quasi-proportional-resonant controller is realized by discretization, and its resonant frequency is set to the grid fundamental frequency, which can provide high gain at the fundamental frequency and realize zero-error tracking of the fundamental sinusoidal current signal. The control block diagram of the quasi-PR control is shown in Figure 6 .

[0131] Based on the ship DC networking system, the closed-loop transfer function of the current inner loop is:

[0132] ,

[0133] wherein, is the current loop proportional coefficient, is the converter gain, L is the filter inductance, C is the filter capacitance.

[0134] The damping coefficient of the current inner loop is:

[0135] ,

[0136] By setting the damping coefficient = 0.707, the optimal value of the current loop proportional coefficient is calculated, which ensures that the system has fast response and good stability.​

[0137] 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:

[0138] ,

[0139] intermediate variables in the formula , , , , and They are respectively:

[0140] ,

[0141] ,

[0142] 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.

[0143] Thus, the closed-loop transfer function of the outer voltage loop is obtained, and its expression is:

[0144] .

[0145] 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:

[0146] .

[0147] The anti-disturbance control method for ship shore power grid connection further comprises a direct-current bus voltage stabilizing step:

[0148] Through the bidirectional DC / DC converter, a double-loop control structure of voltage outer loop and battery current inner loop is adopted, taking the direct-current bus voltage as the control object, generating the current inner loop reference value through the PI regulator, and then taking the battery current as the control object, generating the duty ratio control signal through the PI regulator, so as to maintain the stability of the direct-current bus voltage.

[0149] The method and system of the embodiment are simulated, and the ship direct-current networking power supply system under the control of only the virtual synchronous generator is simulated. The working condition is set as 0.2s connecting 5000W load, 0.5s grid connection, and running for 0.5s. The simulation results of the two are compared. As shown in Figure 7 、 Figure 8 、 Figure 9 and Figure 10 , it can be seen from the figure that the phase tracking of the improved direct-current ship power supply system based on active disturbance rejection control, the system phase tracking, and the oscillation of the grid-side voltage of grid connection voltage, are all stable at 0.05s. Figure 7 The phase tracking result of the direct-current ship power supply system based on the virtual synchronous generator control in the figure, wherein the red line is the phase of the power grid, and the blue line is the tracking phase output based on the virtual synchronous generator control; Figure 8 The control phase tracking result of the direct-current networking ship based on the active disturbance rejection virtual synchronous generator, wherein the red line is the phase of the power grid, and the blue line is the tracking phase output based on the active disturbance rejection virtual synchronous generator. It can be observed that Figure 7 The phase of the power grid and the phase diagram of the traditional virtual synchronous generator control output do not match over time in the figure, while Figure 8 The phase of the power grid and the phase of the output of the improved virtual synchronous generator control based on active disturbance rejection gradually match over time. Figure 8 The grid voltage is the grid voltage waveform output under the two control strategies. It can be observed that Figure 9 The voltage of the power grid and the voltage output by the traditional virtual synchronous generator control do not match over time in the figure, wherein the red line is the grid voltage, and the blue line is the voltage waveform output by the direct-current ship power supply system based on the virtual synchronous generator control; while Figure 10 The voltage of the power grid and the voltage output by the improved virtual synchronous generator control based on active disturbance rejection gradually match over time, wherein the red line is the grid voltage, and the blue line is the voltage waveform output by the direct-current networking ship control based on the active disturbance rejection virtual synchronous generator. Through Figure 7 ,Figure 8 、 Figure 9 and Figure 10 The control of the DC network ship based on the active disturbance rejection virtual synchronous generator can be compared to the control of the DC network ship power supply system only using the virtual synchronous generator.

[0150] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working process of the described modules can refer to the corresponding process in the foregoing method embodiments, and will not be described here.

[0151] The electronic device of the present application includes a central processing unit (CPU) that can perform various appropriate actions and processes in accordance with computer program instructions stored in a read-only memory (ROM) or computer program instructions loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for device operation can also be stored. The CPU, ROM, and RAM are connected to each other through a bus. An input / output (I / O) interface is also connected to the bus.

[0152] A plurality of components in the device are connected to the I / O interface, including: an input unit such as a keyboard, mouse, etc.; an output unit such as various types of displays, speakers, etc.; a storage unit such as a magnetic disk, optical disk, etc.; and a communication unit such as a network card, modem, wireless communication transceiver, etc. The communication unit allows the device to exchange information / data with other devices through a computer network 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 application. For example, in some embodiments, the method of the present application can be implemented as a computer software program that is tangibly embodied in a machine-readable medium such as the storage unit. In some embodiments, part or all of the computer program can be loaded and / or installed on the device via the ROM and / or the communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of the method of the present application described above can be performed. Alternatively, in other embodiments, the CPU can be configured to perform the method of the present application by any other appropriate means (e.g., by means of firmware).

[0153] The functions described above herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, exemplary types of hardware logic components that can be used include field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system on a chip (SOCs), complex programmable logic devices (CPLDs), etc.

[0154] ​Program code for carrying out methods of the present application 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 apparatus to produce a machine, such that the program code, when executed by the processor or controller, produces a means for implementing the functions / operations specified in the flowchart diagrams and / or block diagrams. The program code can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, or entirely on a remote machine or server.

[0155] In the context of the present application, a machine-readable medium can be a tangible medium that can contain or store program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable storage medium can include, but are not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include one or more lines of electrical connections, portable computer disks, hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fibers, portable compact disc read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the foregoing.

[0156] The above descriptions are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for anti-disturbance control of a direct current (DC) network new energy ship shore power grid connection, characterized in that, The specific steps include: S1, collecting input voltage and current signals of the DC side and voltage and current signals of the grid side in real time through a sampling module, and converting them into electrical signals processable by a control module; S2, based on a virtual synchronous generator model constructed based on a rotor motion equation of the synchronous generator, calculating an angular frequency and a phase angle of the virtual synchronous generator according to the voltage and current signals of the grid side; inputting a deviation of the angular frequency from a rated angular frequency into an extended state observer constructed based on a linear active disturbance rejection control technology, and estimating and outputting a total disturbance observation value in real time; S3, calculating an original active power instruction of the virtual synchronous generator model, and fusing the total disturbance observation value with the original active power instruction to generate an active power reference instruction after disturbance rejection; S4, running an SPWM modulation algorithm according to the converted DC side signals in S1 and the active power reference instruction in S3, generating a modulation signal, and using the modulation signal to control the action of a switch tube in a power conversion module; S5, amplifying the modulation signal through a driving module to drive the power conversion module to generate alternating current, and filtering high-frequency harmonics through a filtering module to feed the grid with the alternating current; S6, the sampling module collects the filtered inverter output current in S5 in real time, compares it with a reference current signal composed of the phase angle and the rated voltage generated by S2, and uses a proportional-resonant controller to track the error signal without static error to generate a current compensation signal for real-time correction of the modulation signal.

2. The anti-disturbance control method for DC networking new energy ship shore power grid connection according to claim 1, characterized in that, The adaptive step of 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 index representing the stability of the system is estimated in real time using the recursive least squares method; When the maximum Lyapunov index is greater than a preset instability threshold, a parameter adjustment mechanism is triggered; The adjustment amount of the gain coefficient of the extended state observer is calculated by the gradient descent method, and the gain coefficient is updated according to the adjustment amount.

3. The anti-disturbance control method for DC networking 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 the phase angle of the virtual synchronous generator, and the expression is: ， wherein J is the moment of inertia, ω is the angular frequency of the virtual synchronous generator, ω 0 is the rated angular frequency, is the reference active power, p 0 is the input active power calculated from the grid-side voltage and current signals, is the damping coefficient, is the virtual synchronous generator output phase angle.

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

5. The anti-disturbance control method for DC networking new energy ship shore power grid connection according to claim 1, characterized in that, The extended state observer constructed based on the linear active disturbance rejection control technology in S2 calculates the offset observation value according to the deviation of the angular frequency from the rated angular frequency, and 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, and the expression is: ， ， ， wherein , and are a first, second and third offset observation, respectively; h is a simulation step; , and are observer gain coefficients; is a known dynamics of the controlled object; and are both non-linear functions of the deviation of the angular frequency from the rated angular frequency; k is a time index; is the deviation of the angular frequency from the rated angular frequency; is a gain coefficient of the control quantity; is the n k th control period.

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

7. The anti-disturbance control method for DC networking new energy ship shore power grid connection according to claim 1, characterized in that, In S6, the specific steps for obtaining the input value of the proportional-resonant controller include: Based on the system output voltage amplitude instruction 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 a 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 networking new energy ship shore power grid connection according to claim 7, characterized in that, The transfer function of the quasi-proportional-resonant controller is, on the basis of proportional control, superimposed with resonant control with a specified width at the grid fundamental frequency, and the expression is: ， wherein K p is a proportional coefficient, K i is an integral coefficient, ω s is a cut-off frequency of a low-pass filter, ω 1is the grid fundamental angular frequency.

9. The anti-disturbance control method for DC networking new energy ship shore power grid connection according to claim 1, characterized in that, The method further comprises a direct current bus voltage stabilizing step: Through the bidirectional DC / DC converter, a double-loop control structure of voltage outer loop and battery current inner loop is adopted to take the direct current bus voltage as the control object, generate the current inner loop reference value through the PI regulator, and then take the battery current as the control object, generate the duty cycle control signal through the PI regulator, so as to maintain the stability of the direct current bus voltage.

10. A disturbance-resistant control system for DC networking of shore power of a new energy ship, used for the disturbance-resistant control method for DC networking of shore power of a new energy ship according to any one of claims 1-9, characterized in that, The system comprises a sampling module, a control module, a driving module, a power conversion module and a filtering module; The sampling module is used for real-time acquisition of voltage and current signals of the direct current side and the grid side, and signal conversion and processing; The control module is connected with the sampling module and is used for calculating the angular frequency and the phase angle based on the virtual synchronous generator model; running the extended state observer to estimate the total disturbance in real time; performing feedforward compensation fusion to generate the active power reference instruction after disturbance rejection; running the SPWM modulation algorithm to generate the modulation signal; and executing the current tracking algorithm based on the quasi-proportional-resonant control to generate the current compensation signal; The driving module is connected with the control module and is used for receiving the modulation signal and generating a driving weak current signal; The power conversion module is connected with the driving module and is used for power conversion according to the driving weak current signal to generate alternating current; The filtering module is connected with the power conversion module and is used for filtering high-frequency harmonics in the alternating current and feeding the electrical energy into the grid.

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