A direct current bus voltage control method and system

Abstract

The present application relates to the technical field of direct current bus voltage control, and particularly relates to a direct current bus voltage control method and system, the method comprising the following steps: obtaining real-time internal state parameters of an energy storage unit and a bus current; identifying a load event requiring predictive power scheduling according to a change trend of the bus current; predicting an end voltage of the energy storage unit under the load event based on the real-time internal state parameters; correcting a power instruction for the energy storage unit according to a comparison result of the predicted end voltage of the energy storage unit and a preset safety threshold; and effectively avoiding the energy storage unit from unexpectedly disconnecting from a power grid due to overload or voltage drop by predictively evaluating the performance of the energy storage unit under the load event and correcting the power instruction accordingly, while scheduling a replacement power source in advance to make up for a power gap, thereby significantly improving the stability of the direct current bus voltage and the operation safety of a ship power system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of direct current bus voltage control, and particularly relates to a direct current bus voltage control method and system. BACKGROUND

[0002] In modern ship power systems, the direct current bus as the core of energy convergence and distribution, its voltage stability is crucial for the safe and efficient operation of the ship. The traditional direct current bus voltage control method usually coordinates the power output of the generator set and the energy storage unit to maintain voltage stability. However, in actual operation, especially when the ship faces sudden high-power load demand, such as lateral propeller starting, the existing method exposes significant deficiencies. Specifically, the diesel generator set as the main power source, its inherent mechanical inertia causes its power output response to have unavoidable delay. In the short time of load impact, the generator set cannot timely increase power to meet the demand, at this time the system will immediately call the energy storage unit for instantaneous power support. However, the discharge capacity of the energy storage unit is not infinite and constant. When the remaining capacity of the energy storage unit is low, its internal impedance will increase significantly, causing the terminal voltage to drop sharply during high-current discharge. The traditional control strategy often fails to fully consider the real-time internal state of the energy storage unit, and may still issue power instructions to the energy storage unit that exceed its current capacity range.

[0003] This forced high-current discharge without considering the real-time state of the energy storage unit will further exacerbate the drop of the terminal voltage of the energy storage unit, and even may cause the power electronic converter connected to the energy storage unit to trigger the protection mechanism due to the excessively low input voltage or excessively large current, thereby causing the energy storage unit to unexpectedly disconnect from the power grid. Once the energy storage unit as the key support suddenly exits, and the power of the generator set has not been fully increased, the direct current bus voltage will face the risk of severe fluctuation or even collapse, seriously threatening the safety of ship operation and the stability of the power system. The existing technology needs to be improved in view of the above problems. SUMMARY

[0004] The purpose of the present application is to solve the problems existing in the prior art, and to provide a direct current bus voltage control method and system.

[0005] In a first aspect, the present application provides a direct current bus voltage control method, the method comprising the following steps:

[0006] Obtaining real-time internal state parameters of the energy storage unit and bus current;

[0007] According to the change trend of the bus current, identifying a load event that needs to be scheduled in advance;

[0008] Based on the real-time internal state parameters, predicting the terminal voltage of the energy storage unit under the load event;

[0009] correct the power instruction of the energy storage unit according to a comparison result of the predicted energy storage unit terminal voltage and a preset safety threshold;

[0010] identify a power gap according to the corrected energy storage unit power instruction, and dispatch a substitute power source to make up for the power gap.

[0011] By the technical scheme, the application can predictively evaluate the performance of the energy storage unit under a load event, and correct the power instruction thereof accordingly, effectively avoiding the energy storage unit from unexpectedly disengaging from the power grid due to overload or voltage drop, while dispatching a substitute power source in advance to make up for a power gap, thereby significantly improving the stability of the DC bus voltage and the operation safety of the ship power system.

[0012] The core innovation of the application lies in introducing the acquisition and prediction mechanism of real-time internal state parameters of the energy storage unit, realizing predictive power dispatching of the load event. Specifically, the application acquires real-time internal state parameters of the energy storage unit and bus current, and identifies a load event in advance according to the change trend of the bus current. More importantly, the application can predict the terminal voltage of the energy storage unit under the load event based on the real-time internal state parameters. This prediction capability enables the system to predict the bearing limit of the energy storage unit before the actual voltage drop occurs.

[0013] In a second aspect, a DC bus voltage control system is provided, which comprises:

[0014] an acquisition module configured to acquire real-time internal state parameters of an energy storage unit and bus current;

[0015] an identification module configured to identify a load event requiring predictive power dispatching according to a change trend of the bus current;

[0016] a prediction module configured to predict a terminal voltage of the energy storage unit under the load event based on the real-time internal state parameters;

[0017] a correction module configured to correct a power instruction of the energy storage unit according to a comparison result of the predicted energy storage unit terminal voltage and a preset safety threshold;

[0018] a dispatching module configured to identify a power gap according to the corrected energy storage unit power instruction, and dispatch a substitute power source to make up for the power gap.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] The method realizes its beneficial effects by the following principles: firstly, it acquires the internal state parameters (such as open-circuit voltage, instantaneous equivalent resistance) of the energy storage unit and the bus current in real time, and according to the trend of the bus current, it identifies in advance the load event that may cause voltage fluctuation. Secondly, before the load event occurs, the method accurately predicts the terminal voltage of the energy storage unit under the load event based on the real-time internal state parameters of the energy storage unit. This prediction is crucial because it can assess the actual carrying capacity of the energy storage unit in advance. Thirdly, according to the comparison result of the predicted terminal voltage of the energy storage unit and the preset safety threshold, the method can intelligently correct the power instruction to the energy storage unit, avoiding issuing instructions that exceed its current safe operating range, thereby effectively preventing the energy storage unit from accidentally leaving the grid due to over-discharge or excessively low terminal voltage. Finally, according to the corrected power instruction of the energy storage unit, the method identifies the possible power gap and can foreseeably dispatch alternative power sources (such as generator sets) to timely make up for the power gap, overcoming the inherent response delay of the generator set.

[0021] Through the above technical solution, the present application realizes the transformation of the control strategy from passive response to active foresight. Compared with the prior art, the present application can effectively avoid the accidental disconnection of the energy storage unit due to the deterioration of the internal state under load impact, significantly reduce the risk of sharp fluctuations in the DC bus voltage, and thus greatly improve the stability and reliability of the ship power system, ensuring the safe operation and efficient operation of the ship. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The method flowchart of the present application.

[0023] Figure 2 The system structure schematic diagram of the present application.

[0024] In the figure: 201, acquisition module; 202, identification module; 203, prediction module; 204, correction module; 205, scheduling module. DETAILED DESCRIPTION

[0025] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] like Figure 1 The method for controlling DC bus voltage includes the following steps:

[0028] S101. Obtain the real-time internal state parameters and bus current of the energy storage unit. As one implementation, real-time voltage and current data of the energy storage unit can be periodically collected using sensors. These data are then used to estimate the open-circuit voltage and instantaneous equivalent resistance of the energy storage unit, and these estimated values ​​are used as the real-time internal state parameters. Simultaneously, the current on the DC bus is monitored in real-time using a current sensor to obtain the bus current. For example, voltage and current data can be collected every 100 milliseconds, and the open-circuit voltage and instantaneous equivalent resistance can be calculated every second. As another implementation, multiple temperature sensors can be pre-positioned inside the energy storage unit to acquire real-time temperature data at multiple locations within the unit. Combined with the voltage and current data, the real-time internal state parameters of the energy storage unit are determined using a lookup table method or a preset model. The bus current can be measured in real-time using a Hall effect sensor.

[0029] S102. Identify load events requiring predictive power scheduling based on the changing trend of bus current. As a preferred implementation method, a method based on historical data and machine learning models can be used. For example, by training a neural network model, inputting historical bus current data and ship operating status data (such as speed, rudder angle, etc.), the model outputs a prediction of bus current changes in the near future. When the prediction result shows that a large current fluctuation is about to occur, it is identified as a load event.

[0030] S103. Based on real-time internal state parameters, predict the terminal voltage of the energy storage unit under load events. Alternatively, a simplified energy storage unit model can be established that can predict the terminal voltage of the energy storage unit at a specific time point based on real-time internal state parameters (such as state of charge, temperature, internal resistance, etc.) and the expected discharge current. For example, a first-order RC equivalent circuit model can be used, and by inputting the current open-circuit voltage, ohmic resistance, polarization resistance, and the target power command of the load event, the instantaneous terminal voltage of the energy storage unit when the load event occurs can be calculated.

[0031] S104、According to the comparison result of the predicted energy storage unit terminal voltage and the preset safety threshold, the power instruction to the energy storage unit is corrected; specifically, if the predicted energy storage unit terminal voltage is lower than the preset minimum safety voltage threshold, the power instruction to the energy storage unit needs to be adjusted downward to avoid its terminal voltage being too low. For example, the original power instruction can be multiplied by a correction coefficient less than 1. As a preferred embodiment, the correction coefficient can be dynamically adjusted according to the deviation of the predicted terminal voltage from the safety threshold. For example, the smaller the correction coefficient is when the predicted terminal voltage is closer to or lower than the safety threshold, the more the power instruction is reduced. At the same time, the instantaneous discharge current limit and temperature limit of the energy storage unit also need to be considered to ensure that the corrected power instruction will not cause the energy storage unit to overheat or overheat.

[0032] S105、According to the corrected energy storage unit power instruction, identify the power gap and dispatch the alternative power source to make up for the power gap. For example, after the power instruction of the energy storage unit is corrected, if the corrected energy storage unit power output plus the current power output of the generator set is still insufficient to meet the total power demand of the load event, the amount of this insufficient power is calculated as the power gap. As an embodiment, a power boost instruction can be sent to the generator set to increase the power output to make up for the power gap. For example, if the power gap is 500 kW, an instruction is sent to the generator set controller to require it to boost the power by 500 kW within the allowed ramping rate.

[0033] The DC bus is the core of energy gathering and distribution in the ship power system, and the stability of its voltage is crucial for the safe and efficient operation of the ship. In this system, there are usually energy storage units, generator sets (as an alternative power source) and various loads. Among them, the energy storage unit refers to a device that can store and release electrical energy when needed, such as a battery pack or super capacitor pack, which is mainly used to provide transient power support and voltage stability in the ship power system. Bus current refers to the total current flowing through the DC bus, and its trend can reflect the changes in system load. Load event refers to the load change in the ship power system that requires large power or fast power response, such as the start of a lateral thruster, the operation of a large pump, etc. Predictive power scheduling refers to the strategy of adjusting power output in advance before or at the beginning of the load event to cope with the upcoming power demand. Real-time internal state parameters of the energy storage unit refer to key parameters that reflect the current health status and performance of the energy storage unit, such as its open-circuit voltage, internal resistance, temperature, etc. Terminal voltage refers to the voltage across the energy storage unit in working condition. Power command refers to the command issued to the energy storage unit or alternative power source to require it to output or absorb a specific power. Pre-set safety threshold refers to the voltage or current limit value set to ensure the safe and stable operation of the energy storage unit. Power gap refers to the power difference generated when the power output of the energy storage unit after correction still cannot meet the total power demand of the system. Alternative power source refers to other power sources that can provide power to the DC bus in addition to the energy storage unit, such as diesel generator sets, fuel cells, etc.

[0034] Specifically, first, by continuously acquiring real-time internal state parameters of the energy storage unit and bus current, basic data is provided for subsequent predictive judgment and decision-making. The trend of the bus current can serve as an early warning signal for the impending or ongoing load event, enabling the system to identify in advance the load event that requires predictive power scheduling. This predictive identification is the key starting point of the entire control strategy, which enables the system to change from passive response to active intervention. Once the load event is identified, the system predicts the terminal voltage of the energy storage unit under the load event based on the real-time internal state parameters of the energy storage unit. This prediction step is crucial, as it enables the system to predict the bearing capacity of the energy storage unit before the actual voltage drop occurs. By comparing the predicted terminal voltage of the energy storage unit with the preset safety threshold, the system can determine whether the energy storage unit can safely provide the required power. If the prediction result shows that the terminal voltage of the energy storage unit may be lower than the safety threshold, the system will immediately revise the power instruction to the energy storage unit. This revision avoids issuing a power instruction to the energy storage unit that exceeds its current capacity range, effectively preventing the terminal voltage of the energy storage unit from falling excessively, overcurrent, or overheating due to overloading, thereby avoiding unexpected disconnection of the energy storage unit. Thus, the energy storage unit as a key instantaneous power support source can be continuously and stably operated. After revising the power instruction to the energy storage unit, the system identifies the resulting power gap. Since the power output of the energy storage unit is limited within a safe range, it may not be able to fully meet the load demand, resulting in a power gap. To make up for this gap, the system intelligently schedules alternative power sources, such as diesel generators, to increase their power output. This coordinated scheduling ensures that the power supply and demand of the entire DC bus system is balanced while the energy storage unit is safely operated, effectively suppressing fluctuations in the DC bus voltage and ensuring the stability and reliability of the ship power system. In summary, the method of the present application realizes fine and predictive management of the DC bus voltage through the closed-loop control process of "real-time monitoring-predictive identification-state prediction-instruction revision-coordinated scheduling", significantly improving the stability and safety of the ship power system under complex load conditions.

[0035] As an embodiment of the present application, the step of predicting the terminal voltage of the energy storage unit under the load event based on the real-time internal state parameters comprises:

[0036] obtaining a target power instruction of the load event;

[0037] applying a detection current pulse to the energy storage unit before predicting the terminal voltage of the energy storage unit under the target power instruction;

[0038] measuring the change in terminal voltage of the energy storage unit before and after applying the detection current pulse;

[0039] Based on the terminal voltage change and the detection current pulse, the instantaneous equivalent resistance of the energy storage unit is calculated;

[0040] Based on the instantaneous equivalent resistance and the open-circuit voltage in the real-time internal state parameters, the terminal voltage of the energy storage unit under the target power instruction is predicted.

[0041] Specifically, before predicting the terminal voltage of the energy storage unit under the target power instruction, the target power instruction of the load event needs to be obtained first. The target power instruction refers to the expected power value that the energy storage unit needs to provide or absorb when a specific load event occurs, which can be determined according to system load demand, operation strategy or preset power distribution scheme. Subsequently, in order to obtain the real-time dynamic characteristics of the energy storage unit, a detection current pulse is applied to the energy storage unit. The detection current pulse is usually a short-time, small-amplitude current disturbance, and its purpose is to stimulate the transient response of the energy storage unit without significantly affecting the normal operation of the system. The amplitude and duration of the detection current pulse can be optimized according to the type of the energy storage unit and system requirements to ensure that the instantaneous response can be effectively measured.

[0042] After applying the detection current pulse, the terminal voltage change of the energy storage unit before and after the application of the detection current pulse needs to be measured. The voltage change reflects the internal impedance characteristics of the energy storage unit when it is subjected to a transient current disturbance. Based on the measured terminal voltage change and the known detection current pulse, the instantaneous equivalent resistance of the energy storage unit can be calculated. The instantaneous equivalent resistance is the impedance performance of the energy storage unit under the current operating state to the transient current change, and its calculation method is usually the ratio of the terminal voltage change to the amplitude of the detection current pulse. Finally, based on the calculated instantaneous equivalent resistance and the open-circuit voltage in the real-time internal state parameters, the terminal voltage of the energy storage unit under the target power instruction is predicted. The open-circuit voltage is the terminal voltage of the energy storage unit when no current flows, which is usually related to the state of charge (SOC). By combining the instantaneous equivalent resistance and the open-circuit voltage, the actual terminal voltage of the energy storage unit under a specific power instruction can be more accurately predicted, because the instantaneous equivalent resistance reflects the true internal resistance characteristics of the energy storage unit under dynamic operating conditions.

[0043] The scheme of the present application actively applies a detection current pulse and measures its transient response before predicting the terminal voltage of the energy storage unit, thereby obtaining the instantaneous equivalent resistance of the energy storage unit in real time. This method can dynamically capture the changes in the internal impedance of the energy storage unit, overcoming the prediction errors caused by changes in internal parameters in traditional methods. By combining the real-time instantaneous equivalent resistance with the open-circuit voltage, the voltage response of the energy storage unit under a specific load event can be more accurately simulated, thereby providing a more reliable basis for subsequent power instruction correction.

[0044] In some preferred embodiments, the following is illustrated by a specific example. Assume that a DC bus in a ship power system is connected with an energy storage unit and a large propulsion motor. When the propulsion motor is suddenly started, a significant load event occurs, resulting in a sharp increase in bus current and requiring the energy storage unit to provide a large instantaneous power. To accurately predict the terminal voltage of the energy storage unit under this load event, the system first obtains the target power command required for the propulsion motor to start. Subsequently, before predicting the terminal voltage of the energy storage unit, the system applies a detection current pulse with a duration of 10 milliseconds and an amplitude of 5 amperes to the energy storage unit. At the same time, a high-precision sensor measures the change in the terminal voltage of the energy storage unit before and after the application of the detection current pulse, for example, from 500 volts to 498 volts. Based on this 2-volt voltage change and the 5-ampere detection current pulse, the system calculates that the instantaneous equivalent resistance of the energy storage unit is 0.4 ohms. Combined with the open-circuit voltage corresponding to the current state of charge of the energy storage unit (for example, 510 volts), the system uses Ohm's law to predict that under the target power command of the propulsion motor to start, the terminal voltage of the energy storage unit will drop to 480 volts. This prediction based on the real-time instantaneous equivalent resistance can more accurately reflect the actual voltage drop of the energy storage unit when discharging a large instantaneous current, compared to a prediction that only relies on pre-set or static parameters, thereby making the subsequent correction of the power command to the energy storage unit more accurate and effectively avoiding sharp fluctuations in the bus voltage.

[0045] As an embodiment of the present application, the step of correcting the power command to the energy storage unit according to the comparison result of the predicted terminal voltage of the energy storage unit and the pre-set safety threshold value comprises:

[0046] determining a preliminary power command to the energy storage unit according to the comparison result of the predicted terminal voltage of the energy storage unit and the pre-set safety threshold value;

[0047] obtaining an instantaneous discharge current limit of the energy storage unit;

[0048] determining a current-limited power of the energy storage unit according to the instantaneous discharge current limit;

[0049] obtaining an internal temperature and a temperature change rate of the energy storage unit;

[0050] determining a temperature-limited power of the energy storage unit according to the internal temperature, the temperature change rate and a pre-set temperature threshold value;

[0051] generating a final corrected power command based on the minimum value among the preliminary power command, the current-limited power and the temperature-limited power.

[0052] wherein determining the preliminary power instruction refers to initially calculating the power that the energy storage unit should output, based on considering the safety of the terminal voltage of the energy storage unit. The preliminary power instruction aims to respond to the control requirements of the bus voltage and ensure that the terminal voltage of the energy storage unit does not exceed the preset safety threshold.

[0053] Further, obtaining the instantaneous discharge current limit of the energy storage unit refers to obtaining the maximum instantaneous current that the energy storage unit can safely output in the current state (e.g., based on its state of charge, state of health, and current temperature, etc.). This limit is determined by the inherent physical characteristics of the energy storage unit and the current operating conditions. According to the instantaneous discharge current limit, the current-limiting power of the energy storage unit can be calculated. For example, the current-limiting power can be determined as the product of the instantaneous discharge current limit and the current terminal voltage of the energy storage unit, with the aim of ensuring that the actual output current of the energy storage unit does not exceed its safe carrying capacity.

[0054] In addition, obtaining the internal temperature and temperature change rate of the energy storage unit are key parameters for evaluating the thermal state of the energy storage unit. The internal temperature reflects the overall thermal load of the energy storage unit, while the temperature change rate indicates the dynamic change trend of its thermal load. These parameters are crucial for determining whether the energy storage unit is at risk of overheating or is about to enter a dangerous temperature range. Based on the internal temperature, temperature change rate, and preset temperature threshold, the temperature-limiting power of the energy storage unit can be determined. For example, when the internal temperature or temperature change rate exceeds the preset threshold, the temperature-limiting power will be correspondingly reduced to prevent the energy storage unit from being damaged due to overheating, with the aim of protecting the energy storage unit from thermal stress. Finally, by comparing the preliminary power instruction, the current-limiting power, and the temperature-limiting power, and selecting the minimum value among them as the final revised power instruction. This selection mechanism ensures that the generated power instruction meets the voltage, current, and temperature triple safety constraints, thereby providing comprehensive protection for the energy storage unit.

[0055] The scheme of the present application effectively solves the problems of energy storage unit overload, overheating, or accelerated aging that may be caused by only revising the power instruction based on the terminal voltage by introducing the consideration of the instantaneous discharge current limit and internal temperature of the energy storage unit. Specifically, after determining the preliminary power instruction, the system further obtains the instantaneous discharge current limit of the energy storage unit in the current state and calculates the current-limiting power accordingly. At the same time, the system also monitors the internal temperature and temperature change rate of the energy storage unit and determines the temperature-limiting power in combination with the preset temperature threshold. By comparing the preliminary power instruction with the two limiting powers and selecting the minimum value among them as the final revised power instruction, the scheme ensures that the actual output power of the energy storage unit does not exceed its safety boundaries in terms of current and temperature. This multi-dimensional constraint mechanism makes the revision of the power instruction more comprehensive and precise, thereby avoiding potential risks caused by insufficient consideration of a single dimension.

[0056] As an embodiment of the present application, the step of scheduling the alternative power source to compensate for the power gap comprises:

[0057] obtaining a change rate of the power gap;

[0058] obtaining a power ramping capability of the alternative power source;

[0059] calculating a power output adjustment amount of the alternative power source according to the change rate of the power gap and the power ramping capability;

[0060] adjusting the power output of the alternative power source according to the power output adjustment amount to compensate for the power gap.

[0061] Specifically, the change rate of the power gap refers to the speed at which the power gap changes over time, which can be obtained by difference or derivative operation on real-time power gap data, aiming to reflect the dynamic trend of the power gap. The power ramping capability of the alternative power source refers to the maximum rate at which the power output of the alternative power source can be changed per unit time, which is usually determined by the physical characteristics and control strategy of the alternative power source. For example, for a generator set, the ramping capability is limited by the response speed of the engine and the regulation ability of the generator excitation system; for a battery energy storage system, the ramping capability is limited by the charge-discharge rate of the battery and the response speed of the power converter. Wherein, the calculation of the power output adjustment amount of the alternative power source can be understood as determining the power increment or decrement that the alternative power source should output in the next control period according to the current value of the power gap, the change rate and the power ramping capability of the alternative power source, through a specific control algorithm or model predictive control method. For example, PID (Proportion-Integral-Derivative) control, fuzzy control or model predictive control algorithm can be used to consider the size of the power gap, the change trend and the dynamic response limit of the alternative power source to generate the optimal power adjustment instruction.

[0062] The scheme of the present application introduces the change rate of the power gap and the power ramping capability of the alternative power source, so that the scheduling of the alternative power source is no longer a static compensation based on the current power gap, but can predict the future trend of the power gap and make dynamic adjustments combined with the actual dynamic response capability of the alternative power source. It is precisely because of the comprehensive consideration of the dynamic characteristics of the power gap and the response capability of the alternative power source that the power output adjustment of the alternative power source can be more accurate and timely, thereby effectively avoiding the bus voltage fluctuation caused by scheduling lag or overshoot.

[0063] As an embodiment of the present application, the step of obtaining the real-time internal state parameters of the energy storage unit comprises:

[0064] Real-time voltage data and real-time current data of the energy storage unit are acquired, and the acquisition frequency of the real-time voltage data and the real-time current data is increased when it is identified that the ship power system faces a load impact or an increase in environmental temperature; wherein the real-time voltage data and the real-time current data can be continuously acquired by setting voltage sensors and current sensors at the output end or internal key points of the energy storage unit. In order to ensure that sufficient fine data can be acquired at the critical moment, when the system identifies that the ship power system may face a sudden load impact, such as the start or stop of a large equipment, or a significant change in the environmental temperature, the acquisition frequency of the real-time voltage data and the real-time current data can be dynamically increased. This dynamic adjustment mechanism helps to capture the transient response of the energy storage unit under rapidly changing working conditions, and provides more accurate original data for subsequent parameter calculation.

[0065] A detection current is applied to the energy storage unit, the change in the terminal voltage of the energy storage unit before and after the application of the detection current is measured, and the instantaneous equivalent resistance of the energy storage unit is calculated according to the change in the terminal voltage and the detection current; specifically, a preset small-amplitude detection current pulse can be applied to the energy storage unit during normal operation or in a specific maintenance window. The detection current pulse can be a constant current or a current signal with a specific waveform. Before and after the application of the detection current pulse, the terminal voltage of the energy storage unit is accurately measured. By comparing the change in the terminal voltage before and after the application of the detection current with the applied detection current, the equivalent resistance of the energy storage unit under the instantaneous working condition can be calculated according to Ohm's law or its variants. The instantaneous equivalent resistance reflects the internal resistance characteristics of the energy storage unit at a specific moment, and is crucial for evaluating its power output capability and health status.

[0066] The open-circuit voltage of the energy storage unit is estimated according to the real-time voltage data and the real-time current data; wherein the open-circuit voltage (OCV) of the energy storage unit is a direct reflection of its internal chemical state, and is usually closely related to the state of charge (SOC). The estimation of the open-circuit voltage can be based on the real-time voltage data and the real-time current data, combined with the equivalent circuit model of the energy storage unit or data-driven algorithms. For example, the open-circuit voltage can be approximated by directly measuring the terminal voltage at a stable state with zero or near-zero current, or in a dynamic working condition, the internal voltage drop can be stripped from the real-time voltage and current data by using state estimation algorithms such as Kalman filtering, extended Kalman filtering, unscented Kalman filtering, combined with the voltage response model of the energy storage unit, so as to estimate the open-circuit voltage.

[0067] The instantaneous equivalent resistance and the open-circuit voltage are taken as real-time internal state parameters of the energy storage unit.

[0068] The scheme of the present application ensures the acquisition of high-precision data under critical working conditions by dynamically adjusting the data acquisition frequency, thereby more accurately capturing the transient behavior of the energy storage unit. By applying a detection current and measuring the change in terminal voltage to directly calculate the instantaneous equivalent resistance, errors that may be caused by relying solely on model estimation are avoided, making the evaluation of the internal resistance of the energy storage unit more real-time and accurate. At the same time, the open-circuit voltage is estimated in combination with real-time voltage and current data, which can accurately reflect the state of charge and energy reserve of the energy storage unit. These real-time and accurate internal state parameters provide a solid data foundation for subsequent predictive power scheduling, enabling the system to more accurately predict the terminal voltage of the energy storage unit under load events and make corrections to the power command accordingly, thereby effectively maintaining the stability of the DC bus voltage.

[0069] As an embodiment of the present application, the step of estimating the open-circuit voltage of the energy storage unit according to real-time voltage data and real-time current data comprises:

[0070] Obtaining temperature data of multiple positions inside the energy storage unit;

[0071] Determining a representative temperature of the energy storage unit according to the temperature data of the multiple positions;

[0072] Temperature correcting the real-time voltage data according to the representative temperature;

[0073] Obtaining the instantaneous change rate of the real-time current data, and adjusting the estimation period of the open-circuit voltage according to the instantaneous change rate of the real-time current data;

[0074] Estimating the open-circuit voltage of the energy storage unit according to the temperature-corrected real-time voltage data, the real-time current data, and the estimation period.

[0075] Specifically, acquiring temperature data of multiple positions inside the energy storage unit refers to arranging temperature sensors at different key points inside the energy storage unit (such as the surface of the battery cell, the inside of the module, the inlet / outlet of the cooling system, etc.) to collect temperature information of these positions in real time. These temperature data can reflect the temperature distribution and change inside the energy storage unit. Among them, determining the representative temperature of the energy storage unit according to the temperature data of multiple positions can be understood as obtaining a temperature value that can represent the current overall thermal state of the entire energy storage unit by weighted average, maximum value selection, or calculation based on a thermal model, etc. on the collected temperature data of multiple positions. The representative temperature aims to comprehensively reflect the actual working temperature of the energy storage unit. In actual application, temperature correction of real-time voltage data according to the representative temperature is specifically that, since the open-circuit voltage of the energy storage unit has a certain functional relationship with the temperature (usually negative correlation), it is necessary to use the pre-calibrated open-circuit voltage-temperature characteristic curve or lookup table to compensate or correct the real-time collected terminal voltage data of the energy storage unit according to the determined representative temperature, so as to eliminate the influence of temperature on voltage measurement, so as to make it closer to the true voltage value at standard temperature. In addition, acquiring the instantaneous change rate of real-time current data refers to monitoring the instantaneous change speed of the charging and discharging current of the energy storage unit, such as by calculating the difference of adjacent sampling points or using a sliding window average method. The change rate reflects the mutation degree of the load event. Further, adjusting the estimation period of the open-circuit voltage according to the instantaneous change rate of the real-time current data refers to that when the instantaneous change rate of the real-time current data is large (for example, identifying that the ship power system is facing a large load shock), it indicates that the system is in a state of rapid dynamic change, at this time, in order to more accurately capture the transient response of the energy storage unit, the estimation period of the open-circuit voltage can be shortened, and the estimation frequency can be increased; on the contrary, when the current changes smoothly, the estimation period can be appropriately prolonged to reduce the amount of calculation and improve the stability of the estimation. Thus, estimating the open-circuit voltage of the energy storage unit according to the real-time voltage data corrected by temperature, real-time current data and estimation period, that is, using the voltage data corrected by temperature, real-time current data and dynamically adjusting the estimation period according to the current change rate, through a suitable estimation algorithm (such as Kalman filter, least squares method, equivalent circuit model, etc.) to accurately estimate the open-circuit voltage of the energy storage unit. This step comprehensively considers the influence of temperature and dynamic current on the estimation accuracy.

[0076] The scheme of the present application effectively eliminates the influence of temperature on the open-circuit voltage estimation of the energy storage unit by introducing temperature data at multiple positions inside the energy storage unit and determining a representative temperature, and then performing temperature correction on real-time voltage data, ensuring the accuracy of the estimation results under different ambient temperatures. At the same time, by obtaining the instantaneous change rate of real-time current data and dynamically adjusting the estimation period of the open-circuit voltage accordingly, the estimation process can better adapt to the rapid changes in the load of the ship power system, and can more timely and accurately capture the true state of the energy storage unit during severe current fluctuations, avoiding the lag or errors caused by fixed estimation period. It is precisely because of the compensation of the temperature influence and the adaptive adjustment of the dynamic changes that the estimation of the open-circuit voltage is more robust and accurate.

[0077] Through the above technical scheme, the present application can significantly improve the estimation accuracy and reliability of the open-circuit voltage of the energy storage unit. Specifically, the temperature correction mechanism ensures that the estimation of the open-circuit voltage is not affected by temperature drift within a wide temperature range, making the judgment of the state of charge (SOC) and the state of health (SOH) of the energy storage unit more accurate. In addition, the strategy of dynamically adjusting the estimation period based on the current change rate enables the system to respond quickly and provide more real-time open-circuit voltage data when facing sudden high-power load events, thereby providing more accurate and timely decision-making basis for predictive power scheduling, effectively avoiding the risk of bus voltage fluctuations or energy storage unit overload caused by estimation errors, and improving the stability and safety of the entire DC bus voltage control system.

[0078] As an embodiment of the present application, the step of estimating the open-circuit voltage of the energy storage unit comprises:

[0079] According to the dynamically updated equivalent circuit model of the energy storage unit, the real-time voltage data and real-time current data corrected by temperature are processed to obtain the internal voltage drop information of the energy storage unit;

[0080] In combination with the estimation period, the open-circuit voltage of the energy storage unit is estimated according to the internal voltage drop information and the real-time voltage data corrected by temperature.

[0081] Specifically, the "dynamically updated equivalent circuit model of the energy storage unit" refers to a mathematical model that can reflect the internal electrochemical characteristics and state changes of the energy storage unit in real time. This model can be a simplified equivalent circuit, for example, a structure of an ohmic resistance in series with one or more parallel resistance-capacitance (RC) networks can be used to simulate the ohmic internal resistance, polarization effect and diffusion effect of the energy storage unit. Among them, the parameters of the model, such as ohmic resistance, polarization resistance and diffusion capacitance, will be dynamically adjusted and updated according to the actual operating state, aging degree and ambient temperature of the energy storage unit and other factors, to ensure that the model can accurately represent the current characteristics of the energy storage unit.

[0082] The "processing of the temperature-corrected real-time voltage data and real-time current data" refers to using the above-mentioned dynamically updated equivalent circuit model, combining the temperature-corrected real-time voltage data and real-time current data collected in real time, and calculating and analyzing through model algorithms (such as state observer, Kalman filter, least squares method, etc.). Through this processing, the internal voltage drop of the energy storage unit under the current can be accurately separated.

[0083] In practical applications, "obtaining internal voltage drop information of the energy storage unit" refers to extracting the internal voltage drop of the energy storage unit from the above-mentioned processing process, which usually includes ohmic voltage drop (caused by ohmic resistance) and polarization voltage drop (caused by electrochemical polarization and concentration polarization). These voltage drop information is a key component of the difference between the terminal voltage and the open-circuit voltage of the energy storage unit when current flows through it.

[0084] Therefore, "estimating the open-circuit voltage of the energy storage unit according to the internal voltage drop information and the temperature-corrected real-time voltage data in combination with the estimation period" refers to combining the internal voltage drop information with the temperature-corrected real-time terminal voltage data after obtaining accurate internal voltage drop information, and then calculating the open-circuit voltage of the energy storage unit. The open-circuit voltage can be understood as the ideal voltage of the energy storage unit when no current flows through it. In actual estimation, the open-circuit voltage can be obtained by adding or subtracting (depending on the charging or discharging direction) the internal voltage drop to the real-time terminal voltage. The estimation period, which is mentioned above and adjusted according to the instantaneous change rate of the real-time current data, ensures that the estimation of the open-circuit voltage is carried out within a suitable time window that reflects the instantaneous state of the energy storage unit.

[0085] The reason why the scheme of the present application can improve the estimation accuracy of the open-circuit voltage is that it introduces a dynamically updated equivalent circuit model. Traditional open-circuit voltage estimation methods may only rely on voltage and current data and simple lookup tables, making it difficult to accurately capture the complex nonlinear characteristics and aging effects of the energy storage unit over time. By using a dynamically updated equivalent circuit model, the model can adjust its internal parameters in real time according to the actual operating data of the energy storage unit (such as voltage, current, temperature, etc.), thus more accurately simulating key electrochemical characteristics such as ohmic internal resistance, polarization resistance, and diffusion capacitance of the energy storage unit. It is precisely because this model can dynamically reflect the current state of the energy storage unit that it can more accurately calculate the internal voltage drop information of the energy storage unit when processing the temperature-corrected real-time voltage data and real-time current data. By combining this accurate internal voltage drop information with the real-time terminal voltage and considering the estimation period, a highly accurate open-circuit voltage estimation value can be obtained. This method effectively makes up for the shortcomings of traditional estimation methods in the face of changes in the internal state of the energy storage unit, ensuring the robustness and reliability of open-circuit voltage estimation.

[0086] As an embodiment of the present application, the dynamic updating process of the equivalent circuit model includes:

[0087] When it is identified that the operating time of the energy storage unit reaches a preset period, or the number of charge and discharge cycles reaches a preset threshold, or the internal temperature change rate exceeds a preset threshold, or the deviation between the predicted terminal voltage and the actual terminal voltage continuously exceeds a preset threshold, the dynamic updating of the equivalent circuit model parameters of the energy storage unit is triggered;

[0088] When the dynamic updating of the equivalent circuit model parameters is triggered, a preset current pulse or voltage disturbance signal is applied to the energy storage unit;

[0089] The transient voltage and transient current response data of the energy storage unit to the current pulse or voltage disturbance signal are collected in real time;

[0090] According to the transient voltage and transient current response data and the structure of the equivalent circuit model of the energy storage unit, the instantaneous parameter values of the ohmic resistance, polarization resistance and diffusion capacitance in the equivalent circuit model of the energy storage unit are calculated;

[0091] The instantaneous parameter values are updated to the equivalent circuit model of the energy storage unit.

[0092] Specifically, the equivalent circuit model generally refers to a simplified circuit model used to describe the electrochemical behavior of the energy storage unit (such as a battery), which includes parameters such as ohmic resistance, polarization resistance and diffusion capacitance, which can reflect the internal resistance, polarization effect and diffusion process of the energy storage unit. Dynamic updating refers to adjusting these model parameters in real time or periodically according to the actual operating state and aging degree of the energy storage unit, to ensure that the model can accurately reflect the current characteristics of the energy storage unit.

[0093] Among them, the preset period can be understood as the cumulative operating time of the energy storage unit reaching a certain length of time, for example, every 1000 hours of operation; the preset threshold can refer to the number of charge and discharge cycles reaching a certain number, for example, 500 cycles, or the internal temperature change rate exceeding 2 degrees Celsius per minute, or the deviation between the predicted terminal voltage and the actual terminal voltage continuously exceeding 50 mV for 10 seconds. These trigger conditions aim to ensure that the updating of the model parameters is started in time at the critical moment when the characteristics of the energy storage unit may change significantly, so as to avoid model misalignment.

[0094] In practical applications, the current pulse or voltage disturbance signal is a specific signal used to stimulate the transient response of the energy storage unit, such as a discharge current pulse with a duration of 1 second and an amplitude of 1C (C is the rated capacity of the energy storage unit), or a step voltage signal with an amplitude of 5% of the rated voltage of the energy storage unit. By applying these known signals, the transient response of the energy storage unit can be observed, and the internal parameters can be inferred. The transient voltage and transient current response data refer to detailed data of the time-varying voltage at the terminals of the energy storage unit and the current flowing through the energy storage unit during the application of the disturbance signal. These data contain rich information about the internal impedance and dynamic characteristics of the energy storage unit.

[0095] Further, the ohmic resistance, polarization resistance, and diffusion capacitance are core parameters in the equivalent circuit model. The ohmic resistance reflects the pure resistance loss of the energy storage unit; the polarization resistance and diffusion capacitance describe the charge transfer polarization and concentration polarization effects in the electrochemical reaction process, respectively. By fitting or algorithm processing (such as least squares method, Kalman filtering, etc.) on the transient response data, the instantaneous values of these parameters can be accurately calculated. Finally, these calculated instantaneous parameter values are replaced with the old parameters in the equivalent circuit model, thereby completing the dynamic updating of the model and making it more accurately reflect the current internal state of the energy storage unit.

[0096] The scheme of the present application solves the problem of precision decline of the above-mentioned equivalent circuit model in long-term operation and complex working conditions by introducing a multi-dimensional triggering mechanism and a parameter identification method based on transient response. Specifically, when the running time, the number of charge and discharge cycles, the internal temperature change rate, or the deviation between the predicted terminal voltage and the actual terminal voltage of the energy storage unit reaches the preset condition, it indicates that the internal characteristics of the energy storage unit may have changed significantly, at which time the system can timely trigger the dynamic updating of the model parameters. By applying a preset current pulse or voltage disturbance signal to the energy storage unit and collecting its transient response data in real time, the internal dynamic characteristics of the energy storage unit can be effectively stimulated, thereby obtaining rich information containing the current ohmic resistance, polarization resistance, and diffusion capacitance of the energy storage unit. Based on these transient response data and the structure of the equivalent circuit model, the instantaneous values of these parameters can be accurately calculated and updated to the equivalent circuit model. It is this active, timely, and actual response-based parameter updating mechanism that enables the equivalent circuit model to always maintain high consistency with the actual state of the energy storage unit, thereby providing a more accurate basis for subsequent open-circuit voltage estimation.

[0097] As an embodiment of the present application, according to the transient voltage and transient current response data and the structure of the equivalent circuit model of the energy storage unit, the step of calculating the instantaneous parameter values of the ohmic resistance, polarization resistance, and diffusion capacitance in the equivalent circuit model of the energy storage unit includes:

[0098] Monitoring the electromagnetic environment characteristics in the ship power system; specifically, real-time or periodic detection and analysis of electromagnetic noise, harmonic interference, transient pulses, etc. inside the ship. This can be achieved by deploying electromagnetic sensors, spectrum analyzers, or using existing voltage and current sensor data in the power system to extract features. The purpose is to fully understand the current electromagnetic interference conditions of the environment, providing a basis for subsequent data collection and processing.

[0099] According to the electromagnetic environment characteristics, adjust the collection parameters of the transient voltage and transient current response data, including the sampling window or the number of repeated measurements; specifically, when strong electromagnetic interference is detected, the sampling window can be appropriately extended to capture more complete signal periods, or the number of repeated measurements can be increased to reduce the influence of random noise by averaging multiple measurements. Conversely, when the electromagnetic environment is relatively pure, the sampling window can be shortened or the number of repeated measurements can be reduced to improve the efficiency of data collection. This aims to dynamically optimize the data collection strategy according to the actual environment, ensuring the quality of the collected data.

[0100] According to the collection parameters, collect transient voltage and transient current response data, and perform interference signal separation processing on the transient voltage and transient current response data to obtain transient voltage and transient current response data without electromagnetic interference; interference signal separation processing can use various signal processing techniques, such as digital filtering (e.g. low-pass filtering, band-stop filtering), wavelet transform, independent component analysis (ICA), or noise suppression algorithms based on machine learning. The purpose is to effectively strip the electromagnetic interference component from the original collected data and retain the true transient response information of the energy storage unit, thereby obtaining more pure and accurate transient voltage and transient current response data.

[0101] According to the transient voltage and transient current response data without electromagnetic interference and the structure of the equivalent circuit model of the energy storage unit, calculate the instantaneous parameter values of the ohmic resistance, polarization resistance and diffusion capacitance in the equivalent circuit model of the energy storage unit. This step is based on the known equivalent circuit model (e.g. first-order RC model or second-order RC model) and the purified transient response data, and the model parameters are fitted by least squares method, Kalman filter or other optimization algorithms.

[0102] The scheme of the present application optimizes the data quality at the source by real-time monitoring of the electromagnetic environment characteristics of the ship power system and adaptively adjusting the collection parameters of the transient voltage and transient current response data based on the monitoring results. At the same time, the interference signal separation processing step is introduced to further purify the collected data, effectively removing the influence of electromagnetic interference on the transient response data. It is precisely because of the high-precision, interference-free transient voltage and transient current response data that the subsequent process of calculating the equivalent circuit model parameters of the energy storage unit based on these data is more accurate and reliable.

[0103] The above technical solution significantly improves the accuracy and robustness of the calculation of equivalent circuit model parameters for energy storage units, especially in complex electromagnetic environments. This helps obtain more accurate internal state parameters of the energy storage unit (such as open-circuit voltage and instantaneous equivalent resistance), thereby improving the accuracy of energy storage unit terminal voltage prediction and ultimately optimizing the control effect of the DC bus voltage. This solution effectively solves the impact of electromagnetic interference on the accuracy of energy storage unit model parameter estimation, enhancing the adaptability and reliability of the entire DC bus voltage control system.

[0104] like Figure 2 The DC bus voltage control system shown includes:

[0105] The acquisition module 201 is used to acquire the real-time internal status parameters and bus current of the energy storage unit;

[0106] The identification module 202 is used to identify load events that require predictive power dispatch based on the changing trend of the bus current.

[0107] Prediction module 203 is used to predict the terminal voltage of the energy storage unit under load events based on real-time internal state parameters;

[0108] The correction module 204 is used to correct the power command to the energy storage unit based on the comparison result between the predicted terminal voltage of the energy storage unit and the preset safety threshold.

[0109] The scheduling module 205 is used to identify power gaps based on the corrected power command of the energy storage unit and to schedule alternative power sources to make up for the power gaps.

[0110] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A direct current bus voltage control method, characterized by, The method comprises the following steps: obtaining real-time internal state parameters of the energy storage unit and bus current; identifying a load event requiring predictive power scheduling according to the trend of the bus current; predicting the terminal voltage of the energy storage unit under the load event based on the real-time internal state parameters; correcting the power instruction of the energy storage unit according to the comparison result of the predicted terminal voltage of the energy storage unit and the preset safety threshold; identifying a power gap according to the corrected power instruction of the energy storage unit, and scheduling a replacement power source to make up for the power gap; The step of predicting the terminal voltage of the energy storage unit under the load event based on the real-time internal state parameters comprises: obtaining a target power instruction of the load event; applying a detection current pulse to the energy storage unit before predicting the terminal voltage of the energy storage unit under the target power instruction; measuring the change of the terminal voltage of the energy storage unit before and after the application of the detection current pulse; calculating the instantaneous equivalent resistance of the energy storage unit based on the change of the terminal voltage and the detection current pulse; predicting the terminal voltage of the energy storage unit under the target power instruction based on the instantaneous equivalent resistance and the open-circuit voltage in the real-time internal state parameters; The step of correcting the power instruction of the energy storage unit according to the comparison result of the predicted terminal voltage of the energy storage unit and the preset safety threshold comprises: determining a preliminary power instruction of the energy storage unit according to the comparison result of the predicted terminal voltage of the energy storage unit and the preset safety threshold; obtaining the instantaneous discharge current limit of the energy storage unit; determining the current-limited power of the energy storage unit according to the instantaneous discharge current limit; obtaining the internal temperature and temperature change rate of the energy storage unit; determining the temperature-limited power of the energy storage unit according to the internal temperature, the temperature change rate and the preset temperature threshold; generating a final corrected power instruction based on the minimum value among the preliminary power instruction, the current-limited power and the temperature-limited power.

2. A DC bus voltage control method according to claim 1, characterized in that, The step of scheduling a replacement power source to make up for the power gap comprises: obtaining the change rate of the power gap; obtaining the power ramping capability of the replacement power source; calculating the power output adjustment amount of the replacement power source according to the change rate of the power gap and the power ramping capability; adjusting the power output of the replacement power source according to the power output adjustment amount to make up for the power gap.

3. The DC bus voltage control method of claim 1, wherein The step of obtaining the real-time internal state parameters of the energy storage unit comprises: obtaining real-time voltage data and real-time current data of the energy storage unit, and increasing the collection frequency of the real-time voltage data and real-time current data when identifying that the ship power system is facing a load impact or an increased environmental temperature change; applying a detection current to the energy storage unit, measuring the change of the terminal voltage of the energy storage unit before and after the application of the detection current, and calculating the instantaneous equivalent resistance of the energy storage unit according to the change of the terminal voltage and the detection current; estimating the open-circuit voltage of the energy storage unit according to the real-time voltage data and the real-time current data; taking the instantaneous equivalent resistance and the open-circuit voltage as the real-time internal state parameters of the energy storage unit.

4. A DC bus voltage control method according to claim 3, characterized in that, The step of estimating the open-circuit voltage of the energy storage unit according to the real-time voltage data and the real-time current data comprises: acquiring temperature data of multiple positions inside the energy storage unit; determining a representative temperature of the energy storage unit according to the temperature data of the multiple positions; temperature correcting the real-time voltage data according to the representative temperature; acquiring an instantaneous change rate of the real-time current data, and adjusting an estimation period of the open-circuit voltage according to the instantaneous change rate of the real-time current data; estimating the open-circuit voltage of the energy storage unit according to the temperature corrected real-time voltage data, the real-time current data and the estimation period.

5. A DC bus voltage control method according to claim 4, characterized in that, The step of estimating the open-circuit voltage of the energy storage unit comprises: processing the temperature corrected real-time voltage data and the real-time current data according to the dynamically updated equivalent circuit model of the energy storage unit, to acquire internal voltage drop information of the energy storage unit; combining the estimation period, estimating the open-circuit voltage of the energy storage unit according to the internal voltage drop information and the temperature corrected real-time voltage data.

6. A DC bus voltage control method according to claim 5, characterized in that, The dynamic updating process of the equivalent circuit model comprises: triggering dynamic updating of the equivalent circuit model parameters of the energy storage unit when it is identified that the running time of the energy storage unit reaches a preset period, or the number of charge and discharge cycles reaches a preset threshold, or the internal temperature change rate exceeds a preset threshold, or the deviation between the predicted terminal voltage and the actual terminal voltage continuously exceeds a preset threshold; applying a preset current pulse or voltage disturbance signal to the energy storage unit when the dynamic updating of the equivalent circuit model parameters is triggered; real-time collecting transient voltage and transient current response data of the energy storage unit to the current pulse or voltage disturbance signal; calculating instantaneous parameter values of the ohmic resistance, the polarization resistance and the diffusion capacitance in the equivalent circuit model of the energy storage unit according to the transient voltage and transient current response data and the structure of the equivalent circuit model of the energy storage unit; updating the instantaneous parameter values to the equivalent circuit model of the energy storage unit.

7. A DC bus voltage control method according to claim 6, characterized in that, The step of calculating the instantaneous parameter values of the ohmic resistance, the polarization resistance and the diffusion capacitance in the equivalent circuit model of the energy storage unit according to the transient voltage and transient current response data and the structure of the equivalent circuit model of the energy storage unit comprises: monitoring electromagnetic environment characteristics in the ship power system; adjusting the collection parameters of the transient voltage and transient current response data according to the electromagnetic environment characteristics, the collection parameters including a sampling window or a number of repeated measurements; collecting the transient voltage and transient current response data according to the collection parameters, and performing interference signal separation processing on the transient voltage and transient current response data to acquire transient voltage and transient current response data removed of electromagnetic interference; calculating the instantaneous parameter values of the ohmic resistance, the polarization resistance and the diffusion capacitance in the equivalent circuit model of the energy storage unit according to the transient voltage and transient current response data removed of electromagnetic interference and the structure of the equivalent circuit model of the energy storage unit.

8. A DC bus voltage control system for implementing a DC bus voltage control method according to any one of claims 1 to 7, characterized by The system comprises: an acquisition module configured to acquire real-time internal state parameters of an energy storage unit and a bus current; an identification module configured to identify a load event requiring predictive power scheduling according to a change trend of the bus current; a prediction module configured to predict an end voltage of the energy storage unit under a load event based on the real-time internal state parameter; a correction module configured to correct the power instruction for the energy storage unit according to a comparison result of the predicted end voltage of the energy storage unit and a preset safety threshold; a scheduling module configured to identify a power gap and schedule a replacement power source to make up for the power gap according to the corrected power instruction for the energy storage unit.

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