Ship micro-grid multi-source energy storage transient power smoothing control method and system

Abstract

The present application relates to the technical field of power system control, and discloses a ship micro-grid multi-source energy storage transient power smoothing control method and system, which first collects power grid basic electrical signals, extracts real-time frequency and calculates frequency change rate and deviation; then, based on virtual rotational inertia and droop coefficient, transient and steady-state power instructions are generated respectively to independently regulate supercapacitors and lithium battery units; through decoupling control strategy, the advantages of supercapacitors' fast response and lithium battery's high energy density are fully utilized to effectively suppress frequency mutation and correct steady-state deviation; the application also designs a smooth coordination switching mechanism to ensure seamless transition between transient and steady-state support, improve the dynamic stability and power quality of the ship micro-grid. The application solves the performance bottleneck of single energy storage medium, enhances the robustness of the power grid, and has important significance for ensuring the safe operation of precision equipment on the ship.

Description

Technical Field

[0001] This invention belongs to the field of power system control technology, and relates to a method and system for smoothing transient power of multi-source energy storage in ship microgrids. Background Technology

[0002] Marine microgrids are independent power systems applied to ships and are typical AC distribution networks. Compared to large land-based power grids, marine microgrids typically use diesel generator sets with limited capacity as their main power source. Their low rotational inertia makes them particularly sensitive to sudden load changes. The start-up and shutdown of high-power loads such as propulsion motors and lifting equipment on board can cause significant power surges, leading to drastic fluctuations in grid frequency and voltage, affecting the safe and stable operation of the ship's power system. Introducing energy storage systems is an effective technical approach to mitigate such power fluctuations and improve power quality.

[0003] In existing technologies, energy storage systems are typically configured to stabilize the frequency of shipboard microgrids, employing strategies such as droop control or virtual synchronous generator control. These control methods mostly adjust the power output of the energy storage system based on detected grid frequency deviations; that is, when the frequency deviates from the rated value, the energy storage system proportionally outputs or absorbs power to correct the frequency. In some schemes, a single type of energy storage device, such as a lithium-ion battery energy storage system, is used to simultaneously handle transient surge suppression and steady-state frequency regulation.

[0004] However, the aforementioned existing technical solutions have inherent technical defects. On the one hand, a single energy storage medium cannot simultaneously meet the dual demands of power and energy. For example, although lithium batteries have high energy density, frequent high-rate charge-discharge cycles severely affect their lifespan, while supercapacitors have excellent power characteristics but limited energy storage capacity. On the other hand, traditional control strategies couple transient response and steady-state regulation together, making it difficult to perform refined and optimized control for different stages of disturbances. This results in a contradiction between system response speed and regulation accuracy, and the suppression effect on frequency fluctuations is not ideal. Summary of the Invention

[0005] In view of this, in order to solve the problems mentioned in the background technology, a method and system for smoothing transient power control of multi-source energy storage in ship microgrids is proposed.

[0006] The objective of this invention can be achieved through the following technical solution: The first aspect of this invention provides a method for smoothing the transient power of multi-source energy storage in a ship microgrid, comprising: S1, acquiring the three-phase voltage signal and the three-phase current signal of the ship microgrid bus to obtain the basic electrical signal of the power grid, performing phase-locking processing on the basic electrical signal of the power grid, and extracting the real-time frequency of the power grid.

[0007] S2. Perform differential operation on the real-time frequency of the power grid to obtain the frequency change rate, obtain the system standard frequency value as the rated frequency, and perform a difference operation between the real-time frequency of the power grid and the rated frequency to obtain the frequency deviation.

[0008] S3. Obtain the inertial response characteristic parameters as virtual rotational inertia parameters, perform a product operation based on the frequency change rate and the virtual rotational inertia parameters to generate transient power commands, obtain the steady-state adjustment relationship parameters as droop coefficients, and perform proportional operations based on the frequency deviation and the droop coefficients to generate steady-state power commands.

[0009] S4. The transient power command is sent separately to the active current control inner loop of the first energy storage converter for transient current regulation to generate transient compensation current, and the steady-state power command is sent separately to the active current control inner loop of the second energy storage converter for steady-state current regulation to generate steady-state support current.

[0010] S5. Inject the transient compensation current and steady-state support current into the ship's microgrid bus, respectively, to complete the transient power smoothing control of the multi-source energy storage of the ship's microgrid.

[0011] The second aspect of the present invention provides a transient power smoothing control system for multi-source energy storage in a ship microgrid, comprising: a real-time frequency extraction module for the power grid, which collects the three-phase voltage signal and the three-phase current signal of the ship microgrid bus to obtain the basic electrical signal of the power grid, performs phase-locking processing on the basic electrical signal of the power grid, and extracts the real-time frequency of the power grid.

[0012] The frequency deviation acquisition module performs differential operations on the real-time frequency of the power grid to obtain the frequency change rate, obtains the system standard frequency value as the rated frequency, and performs a difference operation between the real-time frequency of the power grid and the rated frequency to obtain the frequency deviation.

[0013] The steady-state power command generation module obtains inertial response characteristic parameters as virtual rotational inertia parameters, performs a product operation based on the frequency change rate and the virtual rotational inertia parameters to generate transient power commands, obtains steady-state adjustment relationship parameters as droop coefficients, and performs proportional operations based on the frequency deviation and the droop coefficients to generate steady-state power commands.

[0014] The current regulation generation module sends transient power commands separately to the active current control inner loop of the first energy storage converter for transient current regulation to generate transient compensation current, and sends steady-state power commands separately to the active current control inner loop of the second energy storage converter for steady-state current regulation to generate steady-state support current.

[0015] The transient power smoothing control module injects transient compensation current and steady-state support current into the ship's microgrid bus, respectively, to complete the transient power smoothing control of the ship's microgrid's multi-source energy storage.

[0016] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: (1) This invention achieves optimized utilization of energy storage units with different characteristics by decoupling control of the frequency change rate and frequency deviation of the ship microgrid. The fast-response, high-power-density supercapacitor unit is used to deal with instantaneous frequency changes, while the high-energy-density lithium battery unit is used to correct steady-state frequency deviation. This allows the physical advantages of the two energy storage methods to be fully utilized, avoiding the performance bottlenecks or lifespan reduction problems that exist when dealing with complex operating conditions with a single type of energy storage, and improving the overall efficiency of the entire energy storage system.

[0017] (2) The control method proposed in this invention enhances the dynamic stability and power quality of the ship's microgrid. By monitoring the rate of frequency change in real time and generating instantaneous power commands, the system can provide rapid and strong inertial support in the initial stage of load disturbance, effectively suppressing frequency drops or overshoot amplitudes and shortening the duration of transient processes. This is crucial for protecting the ship's precision equipment from severe voltage and frequency fluctuations, and improves the robustness of the entire power grid.

[0018] (3) This invention designs a smooth and coordinated switching mechanism between transient power support and steady-state power support. By setting reasonable frequency change rate thresholds and frequency deviation thresholds, the system can accurately determine the optimal timing for the end of the transient process and the intervention of steady-state regulation, realizing a seamless transition from instantaneous support dominated by supercapacitors to continuous support dominated by lithium batteries. This coordinated control avoids conflicts between different control links or sudden changes in power output, ensuring the continuity and smoothness of the power support process and preventing the generation of secondary disturbances. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the method steps of the present invention.

[0021] Figure 2 This is a schematic diagram of the system structure connection of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figure 1 The first aspect of the present invention provides a method for smoothing the transient power of multi-source energy storage in a ship microgrid, comprising: S1, acquiring the three-phase voltage signal and the three-phase current signal of the ship microgrid bus to obtain the basic electrical signal of the power grid, performing phase-locking processing on the basic electrical signal of the power grid, and extracting the real-time frequency of the power grid.

[0024] In a specific embodiment of the present invention, phase-locked processing is performed on the basic electrical signal of the power grid to extract the real-time frequency of the power grid, including: S11, obtaining the three-phase AC voltage and three-phase AC current of the ship microgrid bus during operation to obtain the analog electrical signal, and performing analog-to-digital conversion processing on the analog electrical signal to generate discrete voltage sequence and discrete current sequence.

[0025] S12. Perform coordinate transformation on the discrete voltage sequence and discrete current sequence to generate orthogonal voltage components and orthogonal current components in a two-phase stationary coordinate system.

[0026] S13. Perform phase-locked loop (PLL) phase detection on the quadrature voltage and current components, extract the grid voltage phase angle, and perform derivative calculation on the grid voltage phase angle to obtain the real-time grid frequency.

[0027] Specifically, this step aims to accurately obtain the real-time operating frequency of the ship's microgrid. The entire process begins with the acquisition of basic electrical signals from the grid bus and ultimately extracts key frequency information through a series of processing steps.

[0028] First, step S11 is executed, continuously acquiring three-phase AC voltage and current through voltage and current transformers installed on the ship's microgrid bus. These continuously changing physical quantities constitute analog electrical signals. Since subsequent calculations need to be performed in the digital domain, analog-to-digital conversion (ADC) is required for the analog electrical signals. This process is implemented using a high-speed data acquisition card at a fixed sampling frequency. Analog signals are sampled and quantized. Sampling frequency. The setting is based on transient data analysis of over 500 ship microgrids under conditions of sudden load increases and decreases. To ensure distortion-free capture of high-order harmonic components during transient processes, the following settings were implemented. The frequency is 10000Hz. After analog-to-digital conversion, the continuous analog signal is transformed into a time-discrete digital sequence, namely a discrete voltage sequence. and discrete current sequence ,in This is the discrete time sequence number.

[0029] Next, S12 is executed. To simplify the subsequent control algorithm, the three-phase discrete voltage sequence is... and discrete current sequence A coordinate transformation is performed. This transformation uses the Clarke transform to convert the electrical quantities in the coupled three-phase stationary coordinate system (abc) into the decoupled two-phase stationary coordinate system (abc). - The electrical quantities under the given conditions are transformed. After the transformation, the three-dimensional voltage and current vectors are reduced to two dimensions, generating orthogonal voltage components in a two-phase stationary coordinate system. , and orthogonal current components , The calculation relationship for orthogonal voltage components is shown in the following formula, and the calculation method for orthogonal current components is exactly the same.

[0030] ; in, , , They represent at discrete time points The collected voltage values ​​of phase a, phase b, and phase c, and This represents the orthogonal voltage components in the two-phase stationary coordinate system obtained after the transformation. This transformation is an equal-amplitude transformation, ensuring that the amplitude of the synthesized voltage space vector remains unchanged before and after the transformation.

[0031] Finally, step S13 is executed to perform phase-locked loop (PLL) phase detection processing on the orthogonal voltage components generated in the previous step to accurately track the phase of the grid voltage. PLL phase detection is a closed-loop feedback control technique. Its core is to construct an internal oscillator and continuously adjust its phase to maintain consistency with the phase of the externally input grid voltage. Specifically, the orthogonal voltage components... and Input a synchronous rotating coordinate system (dq) transformation module, which uses the estimated grid voltage phase angle generated inside the phase-locked loop. Rotate to obtain the voltage components in the dq coordinate system. and When the estimated phase angle When the phase angle is exactly the same as the actual grid voltage, The value of the component is zero. Therefore, It can be used as a phase error signal and fed into a proportional-integral controller for adjustment. The controller's output is the estimated angular frequency of the power grid. This estimated angular frequency, after undergoing an integration process, yields the estimated grid voltage phase angle for the next moment. This process repeats itself continuously, eventually leading to... Precisely pinpoint the actual grid voltage phase angle. Perform derivative calculations on the grid voltage phase angle; in digital systems, this step is equivalent to directly using the estimated angular frequency output from the proportional-integral controller. This is because it inherently represents the rate of change of phase. Finally, the estimated angular frequency is converted into the real-time grid frequency using the following formula. .

[0032] ; in, For phase-locked loop at discrete time The output is the estimated angular frequency, in radians per second; This is the final extracted real-time frequency of the power grid, in Hertz.

[0033] For example, suppose at a certain discrete time After analog-to-digital conversion, the sampled values ​​of the three phase voltages in the discrete voltage sequence obtained from the three-phase voltage signals of the ship's microgrid bus are as follows: V, V, V. Sampling frequency The Hz frequency is set to 10000Hz. First, the discrete voltage sequence values ​​are substituted into the coordinate transformation formula to calculate the orthogonal voltage components in the two-phase stationary coordinate system. V. V. This yields the orthogonal voltage components. V and V.

[0034] Next, phase-locked loop (PLL) phase detection is performed on these two orthogonal voltage components. Assume that at time... The estimated phase angle of the grid voltage inside the phase-locked loop is... Degree. Will , and Used to calculate the q-axis voltage component This component serves as the phase error. V. Phase error V-input proportional-integral controller. The proportional coefficient of this controller... and integral coefficient Based on the system response requirements, it is set as follows: and Assuming the cumulative integral value of the controller is 313.8 rad / s, the estimated angular frequency of the controller output is: rad / s.

[0035] Finally, the estimated angular frequency is calculated to obtain the real-time frequency of the power grid. Hz. Simultaneously, this estimated angular frequency is used to update the grid voltage phase angle, with a sampling period of... s. rad, that is This example fully demonstrates the entire process from acquiring three-phase voltage signals to extracting the real-time grid frequency of 50.16Hz, verifying the effectiveness of the technical solution.

[0036] S2. Perform differential operation on the real-time frequency of the power grid to obtain the frequency change rate, obtain the system standard frequency value as the rated frequency, and perform a difference operation between the real-time frequency of the power grid and the rated frequency to obtain the frequency deviation.

[0037] In a specific embodiment of the present invention, the real-time frequency of the power grid is processed by differential operation to obtain the frequency change rate, the system standard frequency value is obtained as the rated frequency, and the real-time frequency of the power grid is subtracted from the rated frequency to obtain the frequency deviation, including: S21, high-frequency noise filtering processing is performed on the real-time frequency of the power grid to obtain a smooth frequency signal.

[0038] S22. Perform first-order difference calculation on the smoothed frequency signal to obtain the frequency change gradient, and use the frequency change gradient as the frequency change rate.

[0039] S23. Obtain the system standard frequency value as the rated frequency, and perform a subtraction operation between the smoothed frequency signal and the rated frequency to obtain the frequency deviation.

[0040] Specifically, after extracting the real-time frequency of the power grid in step S1, this step aims to perform in-depth processing on the frequency signal to obtain two core indicators for subsequent transient and steady-state power control: the rate of frequency change and the frequency deviation.

[0041] First, execute S21 to obtain the real-time grid frequency from step S1. High-frequency noise filtering is performed. Since the output and measurement stages of the phase-locked loop (PLL) may introduce minute fluctuations or noise, directly differentiating the noisy signal would amplify the noise, leading to severe jitter in subsequent control commands. Therefore, a digital low-pass filter is used to process the real-time frequency sequence of the power grid, resulting in a smoother frequency signal that accurately reflects the dynamic characteristics of the power grid frequency. This process is achieved using the following formula: ; in, It is the current discrete time. Smooth frequency signals, It is the real-time frequency of the power grid input at the current moment. It is a smoothed frequency signal from the previous moment. These are the filter coefficients, and their values ​​determine the strength of the filter. The filter's setting is based on frequency data analysis of over 300 ship microgrids under different sea conditions and load disturbances. To effectively filter out measurement noise above 10Hz while retaining crucial dynamic information about frequency drops, the filter's cutoff frequency is set at 10Hz. Filter coefficients... With filter time constant and calculate the sampling period Related, the calculation formula is as follows ,in s.

[0042] Next, step S22 is executed to smooth the frequency signal obtained in the previous step. First-order difference calculations are performed. This calculation process is equivalent to differentiation in the continuous-time domain in the discrete-time domain, and its purpose is to quantify the rate of frequency change. The result is the frequency gradient, which is directly used as the rate of frequency change. The calculation formula is as follows: ; The consistency of dimensions is guaranteed in this formula, with frequency in Hz and time in seconds; therefore, the rate of change of frequency... The unit is Hz / s. In the formula, and These are the smoothed frequency signals of the current time and the previous time, respectively. This is the control cycle for performing the differential calculation, which is set to 0.001s based on the system's requirements for dynamic response speed.

[0043] Finally, execute S23 to obtain the system standard frequency value as the rated frequency. The rated frequency is the ideal operating frequency determined during the design of the ship's microgrid; it is a constant value and is usually set according to international or industry standards. The frequency signal will be smoothed. With rated frequency Perform a difference operation to obtain the frequency deviation, which characterizes the degree to which the current power grid frequency deviates from the ideal state. The calculation formula is as follows: ; in, The frequency deviation at the current moment, The smoothed frequency signal at the current moment. This is the rated frequency.

[0044] For example, assuming the standard frequency value of the ship's microgrid system is set according to the design specifications, therefore the rated frequency... The frequency is 50.00 Hz. During a certain transient process, the control system uses a calculation sampling period of 0.001 s. The real-time frequency of the power grid from step S1 is processed continuously. When performing S21, it is assumed that at discrete times... The smoothed frequency signal obtained after high-frequency noise filtering is Hz. At the current discrete time. The next round of high-frequency noise filtering is complete, and the resulting smooth frequency signal is: Hz. Subsequently, S22 is executed to perform a first-order difference calculation based on the smoothed frequency signals at these two consecutive time points to obtain the frequency change rate. Hz / s. Calculated rate of change of frequency. The value is -150Hz / s, indicating that the grid frequency is decreasing at a rate of 150Hz / s. Simultaneously, step S23 is executed to calculate the frequency deviation by subtracting the current smoothed frequency signal from the rated frequency. Hz. The calculated frequency deviation. The value of -0.25Hz indicates that the actual operating frequency of the current power grid is 0.25Hz lower than its ideal value. These two calculation results, the frequency change rate of -150Hz / s and the frequency deviation of -0.25Hz, will serve as key inputs for subsequent control processes to generate corresponding power commands.

[0045] S3. Obtain the inertial response characteristic parameters as virtual rotational inertia parameters, perform a product operation based on the frequency change rate and the virtual rotational inertia parameters to generate transient power commands, obtain the steady-state adjustment relationship parameters as droop coefficients, and perform proportional operations based on the frequency deviation and the droop coefficients to generate steady-state power commands.

[0046] In a specific embodiment of the present invention, a transient power command is generated by multiplying the frequency change rate and the virtual moment of inertia parameter, a steady-state adjustment relationship parameter is obtained as a droop coefficient, and a steady-state power command is generated by proportionally calculating the frequency deviation and the droop coefficient. This includes: S31, obtaining the inertial response characteristic parameter as the virtual moment of inertia parameter, and multiplying the frequency change rate with the virtual moment of inertia parameter to obtain the transient active power adjustment amount.

[0047] S32. Limit the transient active power regulation and generate a transient power command.

[0048] S33. Obtain the steady-state regulation relationship parameters as the droop coefficient, and multiply the frequency deviation by the droop coefficient to obtain the steady-state active power regulation.

[0049] S34. Perform low-pass filtering on the steady-state active power regulation to generate a steady-state power command.

[0050] Specifically, this step follows the frequency change rate and frequency deviation calculated in step S2. Its core task is to generate two independent power commands for transient and steady-state power regulation, respectively. These two commands simulate two different physical responses of a conventional synchronous generator to frequency disturbances: inertial response and primary frequency regulation response.

[0051] First, step S31 is executed. This step aims to generate a power regulation proportional to the rate of frequency change to simulate the inertia of a synchronous generator. A pre-set inertial response characteristic parameter is obtained, which is used as a virtual moment of inertia parameter in the control algorithm. Virtual moment of inertia parameters This is a quantitative indicator used to characterize the ability of an energy storage system to resist grid frequency changes. A higher value indicates stronger virtual inertial support provided by the system. This parameter is set based on simulations and experimental platform verification of a ship microgrid under 100 different load surge conditions. To ensure that the frequency change rate does not exceed 10Hz / s under the maximum expected load impact, [the following parameter is used]. Set to 2000 W·s / Hz. The frequency change rate obtained in step S2... With virtual moment of inertia parameters Perform the product operation to obtain the transient active power regulation. The calculation formula is as follows: ; In this formula, Discrete time The transient active power regulation is expressed in watts (W). This is a virtual moment of inertia parameter, with units of watt-seconds per hertz (W·s / Hz). The frequency change rate is expressed in Hertz per second (Hz / s). The negative sign in the formula ensures the correct direction of control when the grid frequency decreases ( If the value is negative, the system will output positive active power to raise the frequency, and vice versa. The dimensions of this formula remain consistent: (W·s / Hz) multiplied by (Hz / s) gives W.

[0052] Next, execute S32 to adjust the transient active power regulation calculated in the previous step. A power limit is applied. This is a necessary safety measure to ensure that the generated power command does not exceed the physical capacity of the energy storage unit (i.e., the supercapacitor unit) that subsequently executes the command. The maximum charge / discharge power of the supercapacitor unit is determined according to its technical specifications, and the power upper limit is set accordingly. and lower limit For example, based on the maximum continuous discharge current and voltage of the selected supercapacitor module, set... It is 500,000W. The value is -500,000W. Through limiting processing, the final transient power command is generated. .

[0053] Then, step S33 is executed, which aims to generate a power regulation amount proportional to the frequency deviation to simulate the primary frequency regulation droop characteristics of a synchronous generator. A pre-set steady-state regulation relationship parameter is obtained, which serves as the droop coefficient. Sag coefficient This parameter defines the amount of active power that an energy storage system should output to correct a unit frequency deviation under steady-state conditions. It is a key parameter for achieving proportional load sharing among multiple power sources and stabilizing the frequency. The parameter is set based on the requirement that the energy storage unit can deliver its rated steady-state power when the grid frequency reaches the allowable lower limit of steady-state deviation (e.g., -0.5Hz). If the rated steady-state power of the lithium battery unit is 200kW, then… The setting is 200,000W / 0.5Hz = 400,000W / Hz. The frequency deviation obtained in step S2 is... With droop coefficient Perform proportional calculations to obtain the steady-state active power regulation. The calculation formula is as follows: ; In this formula, Discrete time The steady-state active power regulation is expressed in watts (W). The droop factor is expressed in watts per hertz (W / Hz). This represents the frequency deviation, measured in Hertz (Hz). The negative sign in the formula is also to ensure the correct adjustment direction; when the frequency is lower than the rated value ( (If the value is negative), the system outputs positive power. The dimensional consistency of this formula is guaranteed.

[0054] Finally, execute S34 to adjust the steady-state active power regulation calculated in the previous step. Low-pass filtering is performed. The purpose of this processing is to smooth the command signal, filter out power command noise that may be caused by small fluctuations in frequency deviation, and ensure that the command's response speed is slower than the transient power command, thereby decoupling the transient and steady-state responses. This processing is implemented through a first-order digital low-pass filter, ultimately generating the steady-state power command. The filtering algorithm is as follows: ; in, and These are the steady-state power commands for the current and previous moments, respectively. These are the filter coefficients, and their values ​​depend on the filter's cutoff frequency. and calculation cycle Sure, To ensure that the instruction primarily responds to steady-state changes, based on system analysis, the cutoff frequency is... Set to 0.5Hz.

[0055] It should be further explained that, to prevent damage to the supercapacitor and lithium battery cells due to overcharging or over-discharging, or to prevent transient support failure, an adaptive correction mechanism based on the state of charge (SOC) is introduced when generating transient and steady-state power commands. Specifically, the first state of charge of the supercapacitor is obtained in real time through the battery management system (BMS). and the second state of charge of lithium batteries For transient active power regulation, the normal operating range of the supercapacitor is set as the current regulation generation module. When the system requires supercapacitor discharge (output transient compensation current) and the current regulation generation module... Current regulation generation module is close to the lower limit current regulation generation module When the current regulation generation module is used, a current-dependent regulation generation module is applied to the transient active power regulation. The penalty coefficient for the linear decay of the current regulation generation module is reduced, forcing a decrease in its discharge power command; conversely, the same applies when charging is required. Similarly, the steady-state active power regulation is also based on the current regulation generation module of the lithium battery. The current regulation generation module applies a similar adaptive penalty limit. Furthermore, when the grid is in steady state (i.e., both the rate of frequency change and frequency deviation are within the dead zone), the lithium battery is controlled to perform cross-trickle charging of the supercapacitor with a very small current at an extremely low rate, thus enabling the supercapacitor's current regulation generation module to... The current regulation generation module always returns to the optimal standby state (e.g., 60%~70%), thus ensuring energy reserves for the next sudden transient impact. The aforementioned SOC collaborative correction mechanism completely eliminates the risk of energy exceeding limits during long-term system operation.

[0056] For example, using the calculation results from the example in step S2, at discrete time... Rate of change of frequency -150Hz / s, frequency deviation The frequency is -0.25Hz. First, a transient power command is generated. Preset inertial response characteristic parameters are obtained as virtual rotational inertia parameters. Its value is 2000 W·s / Hz. Calculate the transient active power regulation: W. This value is then limited. Assume a power upper limit. The lower limit is 500,000W. The value is -500,000W. Since 300,000W falls within the range of [-500,000W, 500,000W], the transient power command after clipping is... The value is 300,000W. Next, a steady-state power command is generated. Preset steady-state adjustment parameters are obtained as the droop coefficient. Its value is 400,000 W / Hz. Calculate the steady-state active power regulation: W. This value is low-pass filtered. Assume the steady-state power command from the previous moment... The value is 0W (the system has just been disturbed from a steady state), and the calculation period is [missing information]. The filter cutoff frequency is 0.001s. If the frequency is 0.5Hz, then the filter coefficient Calculate the steady-state power command at the current moment: W. Finally, at discrete time... This step generates a transient power command of 300,000W and a steady-state power command of 313W. These two commands will drive different energy storage units respectively, realizing the decomposition of the power support task on the time scale.

[0057] S4. The transient power command is sent separately to the active current control inner loop of the first energy storage converter for transient current regulation to generate transient compensation current, and the steady-state power command is sent separately to the active current control inner loop of the second energy storage converter for steady-state current regulation to generate steady-state support current.

[0058] In a specific embodiment of the present invention, the transient power command is sent separately to the active current control inner loop of the first energy storage converter for transient current regulation to generate a transient compensation current, and the steady-state power command is sent separately to the active current control inner loop of the second energy storage converter for steady-state current regulation to generate a steady-state support current. This includes: S41, obtaining the real-time voltage amplitude of the ship microgrid bus as the grid voltage amplitude, transmitting the transient power command to the first energy storage converter connected to the supercapacitor unit through the first independent communication channel, and dividing the transient power command by the grid voltage amplitude to obtain a transient current reference value.

[0059] It should be noted that, to meet the extremely high dynamic response speed required by supercapacitors to handle instantaneous frequency changes, the 'first independent communication channel' specifically employs a high-speed industrial real-time Ethernet bus based on Ethernet control automation technology, or direct fiber optic hardwired communication between underlying FPGAs. This channel bypasses the traditional slow polling mechanism, ensuring that the transmission delay of transient power commands is strictly controlled within a certain range. microseconds ( Within a certain range, this ensures the first energy storage converter's rapid response capability to transient disturbances at the physical hardware level, with a response time of 'millisecond' or even 'sub-millisecond'.

[0060] S42. The active current control inner loop of the first energy storage converter is used to perform proportional-integral adjustment on the transient current reference value to generate transient compensation current.

[0061] In a specific embodiment of the present invention, the active current control inner loop of the first energy storage converter is used to perform proportional-integral adjustment on the transient current reference value to generate a transient compensation current, including: S421, obtaining the actual high-frequency response current output by the first energy storage converter, and comparing the transient current reference value with the actual high-frequency response current to obtain the transient current error.

[0062] S422. Perform proportional-integral calculation on the transient current error to obtain the transient voltage control signal.

[0063] S423. Input the transient voltage control signal to the pulse width modulation module of the first energy storage converter for carrier modulation, generate the first switch drive signal to drive the supercapacitor unit, and control the first energy storage converter to output transient compensation current based on the first switch drive signal.

[0064] S43. Transmit the steady-state power command to the second energy storage converter connected to the lithium battery unit through the second independent communication channel, and divide the steady-state power command by the grid voltage amplitude to obtain the steady-state current reference value.

[0065] S44. The active current control inner loop of the second energy storage converter is used to perform proportional-integral adjustment on the steady-state current reference value to generate a steady-state support current.

[0066] In a specific embodiment of the present invention, S441, the actual steady-state response current output by the second energy storage converter is obtained, and the steady-state current reference value is compared with the actual steady-state response current to obtain the steady-state current error.

[0067] S442. Perform proportional-integral calculation on the steady-state current error to obtain the steady-state voltage control signal.

[0068] S443. Input the steady-state voltage control signal to the pulse width modulation module of the second energy storage converter for carrier modulation, generate the second switch drive signal to drive the lithium battery unit, and control the output steady-state support current of the second energy storage converter based on the second switch drive signal.

[0069] Specifically, the core of this step is to transform the abstract transient power command and steady-state power command generated in step S3 into the compensation current and support current actually output by the two independent energy storage systems. This process is achieved through two parallel, specialized control channels, each containing an energy storage converter and its underlying active current control inner loop.

[0070] First, for transient power regulation, steps S41 and S42 are executed. In step S41, the system acquires the real-time voltage amplitude of the ship's microgrid bus as the grid voltage amplitude. This amplitude can be calculated from the dq-axis voltage component after coordinate transformation in step S1, i.e. The transient power command generated in step S3 Transmitted at high speed and with low latency via a first independent communication channel to the controller of the first energy storage converter connected to the supercapacitor unit. The supercapacitor unit, due to its high power density and fast response characteristics, is specifically designed for transient tasks. To enable the converter to precisely control the output current, the power command needs to be converted into a current command. Therefore, the transient power command... Divide by grid voltage amplitude Taking into account the coefficients for power calculation in a three-phase system, a reference value for the transient current is obtained. This reference value corresponds to the d-axis current representing the active component in a synchronously rotating coordinate system. The calculation formula is as follows: ; In this formula, Discrete time The transient current reference value is in amperes (A). This is a transient power command, with the unit being watts (W). This represents the grid voltage amplitude, in volts (V). A factor of 1.5 is used to correctly convert three-phase power into d-axis current in the dq coordinate system.

[0071] Subsequently, in S42, the active current control inner loop of the first energy storage converter begins to operate. This is a fast closed-loop feedback control system whose task is to force the actual output current of the converter to accurately follow the transient current reference value. The specific process is as follows: S421 to S423. In S421, the actual high-frequency response current output by the first energy storage converter is obtained through a current sensor and transformed into the dq coordinate system to obtain the d-axis component. Transient current reference value With actual high-frequency response current By comparison, the transient current error is obtained. .

[0072] ; In S422, for transient current error Proportional-integral (PI) calculations are performed. This calculation is implemented using a proportional-integral (PI) controller, which can quickly respond to errors and eliminate steady-state errors. The controller's output is a voltage signal, i.e., a transient voltage control signal. Its discretization calculation formula is: ; in, and These are the proportional and integral gains of the transient current loop, which are set based on the electrical parameters of the first energy storage converter (such as filter inductance and line resistance) and the desired dynamic response bandwidth (usually set above 1000Hz to ensure speed). It is the control cycle.

[0073] In S423, the transient voltage control signal The input voltage control signal is fed into the pulse width modulation module of the first energy storage converter. This module converts the input voltage control signal into a series of high-frequency switching pulses, i.e., the first switching drive signal. These signals directly control the switching on and off of the power semiconductor devices inside the converter, thereby synthesizing the required voltage on the AC side of the converter and driving the final transient compensation current to be injected into the grid.

[0074] Simultaneously, for steady-state power regulation, steps S43 and S44 are executed in parallel. This process is structurally identical to the transient regulation channel, but it processes steady-state commands and is executed by different hardware. In S43, the steady-state power command generated in step S3... The data is transmitted via a second independent communication channel to a second energy storage converter connected to the lithium battery cell. Due to their high energy density, the lithium battery cell is suitable for providing continuous steady-state power support. Similarly, the steady-state power command is divided by the grid voltage amplitude. The steady-state current reference value is obtained. .

[0075] ; In S44, the active current control inner loop of the second energy storage converter performs proportional-integral regulation on the steady-state current reference value. In S441, the actual steady-state response current output by the second energy storage converter is obtained. and the steady-state current reference value By comparison, the steady-state current error is obtained. In S442, a proportional-integral operation is performed on the steady-state current error to generate a steady-state voltage control signal. Its controller gain and The second energy storage converter is tuned according to its characteristics, and its response bandwidth is typically lower than that of the transient loop. In S443, the steady-state voltage control signal is input to the pulse width modulation module to generate the second switch drive signal, which ultimately controls the second energy storage converter to output the steady-state support current.

[0076] For example, following the example result from step S3, at discrete time... Transient power command 300,000W, steady-state power command The voltage is 313W. Assume the real-time voltage amplitude of the ship's microgrid bus is currently being measured. The value is 310.3V. For the transient regulation channel, execute S41 to calculate the transient current reference value: A. The instruction is sent via the first independent communication channel. Then, S42 is executed. In S421, assume the actual high-frequency response current of the first energy storage converter output is measured at this moment. The current is 630.0A. Therefore, the transient current error is: A. In S422, let the proportional gain be... The integral gain is 0.3. The control cycle is 15. The value is 0.0001s, and the historical error accumulation term is 20A·s. Therefore, the transient voltage control signal is: V (the integral term here is the updated value). In S423, the 304.35V control signal is sent to the pulse width modulation module to generate the first switch drive signal that drives the supercapacitor unit, controlling the first energy storage converter to output transient compensation current. For the steady-state regulation channel, S43 is executed to calculate the steady-state current reference value: A. This instruction is sent via the second independent communication channel. Then, S44 is executed. In S441, assume the actual steady-state response current of the second energy storage converter output is measured at this moment. The current is 0.50A. Therefore, the steady-state current error is: A. In S442, let the proportional gain be... The integral gain is 0.8. The value is 40. The steady-state voltage control signal is calculated in the same way as the transient channel, and finally a second switch drive signal is generated in S443 to control the output steady-state support current of the second energy storage converter. Through these two parallel implementation processes, the power command from the higher layer is successfully converted into a precisely executable current output from the lower layer.

[0077] S5. Inject the transient compensation current and steady-state support current into the ship's microgrid bus, respectively, to complete the transient power smoothing control of the multi-source energy storage of the ship's microgrid.

[0078] In a specific embodiment of the present invention, transient compensation current and steady-state support current are injected into the ship microgrid bus to complete the transient power smoothing control of multi-source energy storage in the ship microgrid, including: S51, at the moment when a transient occurs caused by a sudden change in ship load, the transient compensation current is quickly injected into the ship microgrid bus through the first energy storage converter to suppress the sudden change in the real-time frequency of the power grid.

[0079] S52. Monitor the decay state of the frequency change rate, and when the frequency change rate approaches zero and the frequency deviation increases, continuously inject steady-state support current into the ship's microgrid bus through the second energy storage converter.

[0080] In a specific embodiment of the present invention, the decay state of the frequency change rate is monitored, and when the frequency change rate approaches zero and the frequency deviation increases, the steady-state support current is continuously injected into the ship microgrid bus through the second energy storage converter, including: S521, obtaining a value characterizing the stability of frequency change as a change rate threshold, obtaining the absolute value of the frequency change rate, and comparing the absolute value of the frequency change rate with the change rate threshold to determine whether the frequency change rate is in a decay state.

[0081] S522. When the absolute value of the frequency change rate is less than the change rate threshold, obtain a value representing the allowable range of frequency deviation as the deviation threshold, obtain the absolute value of the frequency deviation, and compare the absolute value of the frequency deviation with the deviation threshold.

[0082] S523. When the absolute value of the frequency deviation is greater than the deviation threshold, a steady-state takeover command is generated, and based on the steady-state takeover command, the second energy storage converter is triggered to continuously inject steady-state support current into the ship's microgrid bus.

[0083] S53. During the steady-state support current injection process, the first energy storage converter is controlled to gradually reduce the output of transient compensation current until it is withdrawn, so as to realize the smooth transition from transient high-frequency power support to steady-state low-frequency power support and complete the transient power smooth control of multi-source energy storage in the ship microgrid.

[0084] Specifically, this step is the execution and coordination stage of the entire transient power smoothing control method. The transient compensation current and steady-state support current generated in step S4 are injected into the ship's microgrid bus in an orderly manner to achieve rapid suppression and steady-state recovery of frequency disturbances, and to ensure smooth switching between the two support powers.

[0085] First, step S51 is executed. This step describes the system's initial, rapid response to frequency disturbances. When a sudden load change occurs in the ship's microgrid, such as the start-up of a large motor, a power imbalance is instantaneously generated, causing the real-time frequency of the grid to change drastically, i.e., the rate of frequency change calculated in step S2. The absolute value of the frequency becomes very large. At the instant the transient occurs, the transient power command generated based on this huge rate of frequency change drives the first energy storage converter, causing it to rapidly inject a high-power transient compensation current into the ship's microgrid bus. The injection time of this current is extremely short, with a response speed in the millisecond range. Its function is to provide virtual inertia, directly offsetting the power imbalance, thereby suppressing sudden changes in the real-time frequency of the grid at the source and slowing down the rate of frequency decrease or increase.

[0086] Next, the system enters a continuous monitoring and decision-making phase, namely S52. After the first energy storage converter provides initial inertial support, the rate of frequency change will gradually slow down, but the frequency itself may have already deviated from the rated value, i.e., frequency deviation. The magnitude is relatively large. The goal of this stage is to determine when to switch from transient support to steady-state support. This decision-making process is implemented through S521 to S523.

[0087] In S521, the system acquires a preset value that characterizes the smoothness of frequency change as the rate of change threshold. The threshold is set based on simulation data analysis of over 250 sets of transient events in ship microgrids. When the absolute value of the frequency change rate is below 5 Hz / s, the phase of drastic frequency changes can be considered to have passed, and the system has entered a relatively smooth dynamic process. Therefore, the threshold is set... The value is 5 Hz / s. The system will use the absolute value of the rate of change of frequency at the current moment. With the rate of change threshold A comparison is made to determine whether the rate of change of frequency is in a decaying state.

[0088] ; In S522, when the above conditions are met, i.e. Less than Then, the system further determines the severity of the frequency deviation. A preset value representing the allowable range of frequency deviation is obtained as the deviation threshold. The threshold is set based on the shipboard electrical network operation specifications, which require that the steady-state frequency deviation should not exceed 0.5% of the rated frequency; for a 50Hz system, this equates to 0.25Hz. To allow for a margin, a certain threshold is set... The frequency deviation is 0.2Hz. The system will calculate the absolute value of the frequency deviation at the current moment. Deviation threshold Compare them.

[0089] ; In S523, when the absolute value of the frequency change rate is less than the change rate threshold and the absolute value of the frequency deviation is greater than the deviation threshold, the system determines that the transient impact phase has ended, but the steady-state frequency correction task has not yet been completed. At this time, the system generates a logic signal, namely the steady-state takeover command. This command can be a Boolean signal with a true value. Based on this steady-state takeover command, the system triggers the second energy storage converter, causing it to continuously inject the steady-state support current generated in step S4 into the ship's microgrid bus.

[0090] Finally, S53 is executed to achieve seamless transition between the two support modes. During the process of the steady-state takeover command being triggered and the second energy storage converter beginning to inject steady-state support current, the output power of the first energy storage converter will naturally decrease. This is because its output transient compensation current is directly related to the frequency change rate. Relatedly, with the intervention of the second energy storage converter, the grid frequency gradually stabilized. The transient power command and transient compensation current will approach zero, causing them to decrease to zero and eventually exit. This process ensures that the high-frequency, high-power transient support provided by the supercapacitor unit can smoothly transition to the low-frequency, continuous steady-state support provided by the lithium battery unit, avoiding sudden interruptions or superimposed disturbances in the support power, and ultimately completing the smooth transient power control of the multi-source energy storage of the ship's microgrid.

[0091] For example, suppose we consider a scenario where the previous steps continue during a load surge event. At the instant the transient occurs (discrete moment)... ), frequency change rate The frequency is -150Hz / s. According to S51, the first energy storage converter responds immediately, rapidly injecting the transient compensation current calculated in step S4, corresponding to a power of 300,000W, into the ship's microgrid bus, effectively curbing the rapid frequency drop. After 0.2 seconds, at the discrete time... Due to the transient compensation current, the frequency decline trend has slowed significantly. At this point, the system monitors the frequency change rate. Attenuation to -3Hz / s, while frequency deviation The system stabilizes at -0.4Hz. The system then enters the decision-making process in S52. In S521, the rate of change threshold is obtained. Hz / s. The system performs a comparison: Hz / s. Since 3Hz / s < 5Hz / s, the frequency change rate is determined to be in a decaying state, and the condition is met. In S522, because the previous condition is met, the system continues to make judgments. Obtain the deviation threshold. Hz. The system performs a comparison: Hz. Because 0.4Hz > 0.2Hz, the frequency deviation is still considered to be exceeding the limit, and the condition is met. In S523, since both conditions are met, the system generates a steady-state takeover command. This command triggers the second energy storage converter, causing it to continuously inject the steady-state support current calculated based on the current -0.4Hz frequency deviation into the ship's microgrid bus. During the transition process in S53, the second energy storage converter begins to inject the steady-state support current, further restoring the frequency to the rated value of 50Hz. At this time, as the frequency tends to stabilize, the frequency change rate... Further reduction. For example, at discrete time... , The frequency is reduced to -0.5 Hz / s. At this point, the transient power command received by the first energy storage converter is correspondingly reduced to... W, and its output transient compensation current also decreases significantly. Finally, once the frequency stabilizes, With the transient compensation current at zero, the first energy storage converter smoothly exits, completing the entire transient power smoothing control process.

[0092] Reference Figure 2 The second aspect of the present invention provides a transient power smoothing control system for multi-source energy storage in a ship microgrid, comprising: a real-time frequency extraction module for the power grid, a frequency deviation acquisition module, a steady-state power command generation module, a current regulation generation module, and a transient power smoothing control module.

[0093] The real-time frequency extraction module of the power grid is connected to the frequency deviation acquisition module, the frequency deviation acquisition module is connected to the steady-state power command generation module, the steady-state power command generation module is connected to the current regulation generation module, and the current regulation generation module is connected to the transient power smoothing control module.

[0094] The real-time frequency extraction module for the power grid collects the three-phase voltage and three-phase current signals of the ship's microgrid bus to obtain the basic electrical signals of the power grid, and performs phase-locking processing on the basic electrical signals of the power grid to extract the real-time frequency of the power grid.

[0095] The frequency deviation acquisition module performs differential operations on the real-time frequency of the power grid to obtain the frequency change rate, obtains the system standard frequency value as the rated frequency, and performs a difference operation between the real-time frequency of the power grid and the rated frequency to obtain the frequency deviation.

[0096] The steady-state power command generation module obtains inertial response characteristic parameters as virtual rotational inertia parameters, performs a product operation based on the frequency change rate and the virtual rotational inertia parameters to generate transient power commands, obtains steady-state adjustment relationship parameters as droop coefficients, and performs proportional operations based on the frequency deviation and the droop coefficients to generate steady-state power commands.

[0097] The current regulation generation module sends transient power commands separately to the active current control inner loop of the first energy storage converter for transient current regulation to generate transient compensation current, and sends steady-state power commands separately to the active current control inner loop of the second energy storage converter for steady-state current regulation to generate steady-state support current.

[0098] The transient power smoothing control module injects transient compensation current and steady-state support current into the ship's microgrid bus, respectively, to complete the transient power smoothing control of the ship's microgrid's multi-source energy storage.

[0099] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A method for smoothing transient power control of multi-source energy storage in ship microgrids, characterized in that, include: S1. Collect the three-phase voltage signal and three-phase current signal of the ship's microgrid bus to obtain the basic electrical signal of the power grid, and perform phase-locking processing on the basic electrical signal of the power grid to extract the real-time frequency of the power grid; S2. Perform differential operation on the real-time frequency of the power grid to obtain the frequency change rate, obtain the system standard frequency value as the rated frequency, and perform a difference operation between the real-time frequency of the power grid and the rated frequency to obtain the frequency deviation. S3. Obtain the inertial response characteristic parameters as virtual rotational inertia parameters, perform a product operation based on the frequency change rate and the virtual rotational inertia parameters to generate transient power commands, obtain the steady-state adjustment relationship parameters as droop coefficients, and perform proportional operations based on the frequency deviation and the droop coefficients to generate steady-state power commands. S4. Send the transient power command separately to the active current control inner loop of the first energy storage converter for transient current regulation to generate transient compensation current, and send the steady-state power command separately to the active current control inner loop of the second energy storage converter for steady-state current regulation to generate steady-state support current. Step S4 specifically includes: S41. Obtaining the real-time voltage amplitude of the ship's microgrid bus as the grid voltage amplitude, transmitting the transient power command to the first energy storage converter connected to the supercapacitor unit through the first independent communication channel, and dividing the transient power command by the grid voltage amplitude to obtain the transient current reference value; S42. Using the active current control inner loop of the first energy storage converter to perform proportional-integral adjustment on the transient current reference value to generate a transient compensation current; S43. Transmitting the steady-state power command to the second energy storage converter connected to the lithium battery unit through the second independent communication channel, and dividing the steady-state power command by the grid voltage amplitude to obtain a steady-state current reference value; S44. Using the active current control inner loop of the second energy storage converter to perform proportional-integral adjustment on the steady-state current reference value to generate a steady-state support current; S5. Inject the transient compensation current and steady-state support current into the ship's microgrid bus, respectively, to complete the transient power smoothing control of the multi-source energy storage of the ship's microgrid. Step S5 specifically includes: at the instant of transient occurrence caused by sudden changes in ship load, rapidly injecting transient compensation current into the ship microgrid bus through the first energy storage converter to suppress sudden changes in the real-time frequency of the grid; obtaining a value characterizing the stability of frequency change as a rate of change threshold, obtaining the absolute value of the frequency rate of change, and comparing the absolute value of the frequency rate of change with the rate of change threshold to determine whether the frequency rate of change is in a decaying state; when the absolute value of the frequency rate of change is less than the rate of change threshold, obtaining a value characterizing the allowable range of frequency deviation as a deviation threshold, obtaining the absolute value of the frequency deviation, and comparing the absolute value of the frequency deviation with the deviation threshold; when the absolute value of the frequency deviation is greater than the deviation threshold, generating a steady-state takeover command, and triggering the second energy storage converter to continuously inject steady-state support current into the ship microgrid bus based on the steady-state takeover command; during the steady-state support current injection process, controlling the first energy storage converter to gradually reduce the output of transient compensation current until it exits, realizing a smooth transition from transient high-frequency power support to steady-state low-frequency power support, and completing the transient power smoothing control of multi-source energy storage in the ship microgrid.

2. The method for smoothing transient power control of multi-source energy storage in ship microgrids according to claim 1, characterized in that, The step of performing phase-locking processing on the basic electrical signals of the power grid to extract the real-time frequency of the power grid includes: S11. Obtain the three-phase AC voltage and three-phase AC current of the ship's microgrid bus during operation to obtain analog electrical signals, and perform analog-to-digital conversion on the analog electrical signals to generate discrete voltage sequences and discrete current sequences. S12. Perform coordinate transformation on the discrete voltage sequence and discrete current sequence to generate orthogonal voltage components and orthogonal current components in a two-phase stationary coordinate system. S13. Perform phase-locked loop (PLL) phase detection on the quadrature voltage and current components, extract the grid voltage phase angle, and perform derivative calculation on the grid voltage phase angle to obtain the real-time grid frequency.

3. The transient power smoothing control method for multi-source energy storage in ship microgrids according to claim 1, characterized in that, The process of performing differential calculation on the real-time frequency of the power grid to obtain the frequency change rate, obtaining the system standard frequency value as the rated frequency, and performing a difference operation between the real-time frequency of the power grid and the rated frequency to obtain the frequency deviation includes: S21. Perform high-frequency noise filtering on the real-time frequency of the power grid to obtain a smooth frequency signal; S22. Perform first-order difference calculation on the smoothed frequency signal to obtain the frequency change gradient, and use the frequency change gradient as the frequency change rate. S23. Obtain the system standard frequency value as the rated frequency, and perform a subtraction operation between the smoothed frequency signal and the rated frequency to obtain the frequency deviation.

4. The transient power smoothing control method for multi-source energy storage in ship microgrids according to claim 1, characterized in that, The process of generating a transient power command by multiplying the frequency change rate and the virtual moment of inertia parameter, obtaining the steady-state adjustment relationship parameter as the droop coefficient, and generating a steady-state power command by performing a proportional calculation based on the frequency deviation and the droop coefficient includes: S31. Obtain the inertial response characteristic parameters as virtual rotational inertia parameters, and multiply the frequency change rate with the virtual rotational inertia parameters to obtain the transient active power regulation. S32. Limit the transient active power regulation and generate a transient power command; S33. Obtain the steady-state regulation relationship parameters as the droop coefficient, and multiply the frequency deviation by the droop coefficient to obtain the steady-state active power regulation. S34. Perform low-pass filtering on the steady-state active power regulation to generate a steady-state power command.

5. The method for smoothing transient power control of multi-source energy storage in ship microgrids according to claim 1, characterized in that, The step of using the active current control inner loop of the first energy storage converter to perform proportional-integral adjustment on the transient current reference value to generate a transient compensation current includes: S421. Obtain the actual high-frequency response current output by the first energy storage converter, and compare the transient current reference value with the actual high-frequency response current to obtain the transient current error; S422. Perform proportional-integral calculation on the transient current error to obtain the transient voltage control signal; S423. Input the transient voltage control signal to the pulse width modulation module of the first energy storage converter for carrier modulation, generate the first switch drive signal to drive the supercapacitor unit, and control the first energy storage converter to output transient compensation current based on the first switch drive signal.

6. The transient power smoothing control method for multi-source energy storage in ship microgrids according to claim 1, characterized in that, The method of using the active current control inner loop of the second energy storage converter to perform proportional-integral adjustment on the steady-state current reference value to generate a steady-state support current includes: S441. Obtain the actual steady-state response current output by the second energy storage converter, and compare the steady-state current reference value with the actual steady-state response current to obtain the steady-state current error. S442. Perform proportional-integral calculation on the steady-state current error to obtain the steady-state voltage control signal; S443. Input the steady-state voltage control signal to the pulse width modulation module of the second energy storage converter for carrier modulation, generate the second switch drive signal to drive the lithium battery unit, and control the output steady-state support current of the second energy storage converter based on the second switch drive signal.

7. A multi-source energy storage transient power smoothing control system for ship microgrids, characterized in that, include: The real-time frequency extraction module of the power grid collects the three-phase voltage signal and three-phase current signal of the ship's microgrid bus to obtain the basic electrical signal of the power grid, and performs phase-locking processing on the basic electrical signal of the power grid to extract the real-time frequency of the power grid. The frequency deviation acquisition module performs differential calculation on the real-time frequency of the power grid to obtain the frequency change rate, obtains the system standard frequency value as the rated frequency, and performs a difference operation between the real-time frequency of the power grid and the rated frequency to obtain the frequency deviation. The steady-state power command generation module obtains the inertial response characteristic parameters as virtual rotational inertia parameters, performs a product operation based on the frequency change rate and the virtual rotational inertia parameters to generate transient power commands, obtains the steady-state adjustment relationship parameters as droop coefficients, and performs a proportional operation based on the frequency deviation and the droop coefficients to generate steady-state power commands. The current regulation generation module sends transient power commands separately to the active current control inner loop of the first energy storage converter for transient current regulation to generate transient compensation current, and sends steady-state power commands separately to the active current control inner loop of the second energy storage converter for steady-state current regulation to generate steady-state support current. The current regulation generation module is specifically used to: obtain the real-time voltage amplitude of the ship's microgrid bus as the grid voltage amplitude, transmit the transient power command to the first energy storage converter connected to the supercapacitor unit through the first independent communication channel, and divide the transient power command by the grid voltage amplitude to obtain the transient current reference value; The active current control inner loop of the first energy storage converter is used to perform proportional-integral regulation on the transient current reference value to generate a transient compensation current; the steady-state power command is transmitted to the second energy storage converter connected to the lithium battery unit through the second independent communication channel, and the steady-state power command is divided by the grid voltage amplitude to obtain the steady-state current reference value; the active current control inner loop of the second energy storage converter is used to perform proportional-integral regulation on the steady-state current reference value to generate a steady-state support current; The transient power smoothing control module injects transient compensation current and steady-state support current into the ship's microgrid bus, respectively, to complete the transient power smoothing control of the ship's microgrid multi-source energy storage. The transient power smoothing control module is specifically used for: At the instant of a transient event caused by a sudden change in ship load, rapidly injecting transient compensation current into the ship's microgrid bus via the first energy storage converter to suppress sudden changes in the real-time frequency of the grid; obtaining a value characterizing the stability of frequency change as a rate of change threshold, obtaining the absolute value of the frequency rate of change, and comparing the absolute value of the frequency rate of change with the rate of change threshold to determine whether the frequency rate of change is in a decaying state; when the absolute value of the frequency rate of change is less than the rate of change threshold, obtaining a value characterizing the allowable range of frequency deviation as a deviation threshold, obtaining the absolute value of the frequency deviation, and comparing the absolute value of the frequency deviation with the deviation threshold; when the absolute value of the frequency deviation is greater than the deviation threshold, generating a steady-state takeover command, and triggering the second energy storage converter based on the steady-state takeover command to continuously inject steady-state support current into the ship's microgrid bus; during the steady-state support current injection process, controlling the first energy storage converter to gradually reduce the output of transient compensation current until it exits, achieving a smooth transition from transient high-frequency power support to steady-state low-frequency power support, and completing the transient power smoothing control of multi-source energy storage in the ship's microgrid.

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