A multi-port solid-state transformer coordinated control method and device, a terminal and a medium

Abstract

The application discloses a kind of multi-port solid state transformer coordination control method, device, terminal and medium, it is related to power distribution network technical field, the scheme provided in the present application is matched with bus voltage hierarchical threshold by equipment type division, the coordination control logic of different equipment is dynamically matched, the collaborative optimization of photovoltaic power generation maximum power tracking, energy storage charge-discharge power regulation and load hierarchical switching is realized, ensure that photovoltaic, energy storage and load equipment form optimal cooperation under different working conditions, with the advantages of improving the reliability of multi-energy system power supply and power quality, avoiding direct current bus voltage overrun and equipment overload risk.

Description

Technical Field

[0001] This application relates to the field of power distribution network technology, and in particular to a multi-port solid-state transformer coordinated control method, device, terminal and medium. Background Technology

[0002] As the proportion of renewable energy connected to the power system increases, the power system is shifting from a traditional "one-to-many" to a "many-to-many" model, making energy flow more complex. Solid-state transformers have become key equipment for coordinating source, storage, and load resources. Existing multi-port solid-state transformer coordination control strategies are divided into centralized and distributed approaches. Centralized strategies rely on interconnection communication, which suffers from a single decision-making center, heavy communication burden, and high failure risk. While distributed strategies do not require communication, they assign power balance control objectives to different controllers, resulting in limited coordination in complex scenarios.

[0003] When the AC grid is disconnected from the solid-state transformer due to a fault, the solid-state transformer enters an islanded operation state. At this time, the solid-state transformer should effectively regulate the power flow within the islanded area to ensure a stable and reliable power supply in the area and prevent power imbalance within the island. However, in actual scenarios, since the coordination control strategy of multi-port solid-state transformers is still in its infancy, it is difficult to effectively balance the coupling and coordinated operation between the source, storage and load, resulting in poor reliability of the multi-port solid-state transformer coordination control technology. Summary of the Invention

[0004] This application provides a multi-port solid-state transformer coordinated control method, device, terminal, and medium to solve the technical problem of low reliability in existing multi-port solid-state transformer coordinated control.

[0005] To address the aforementioned technical problems, the first aspect of this application provides a coordinated control method for multi-port solid-state transformers, comprising:

[0006] Based on the topology information of the multi-port solid-state transformer, determine the connection device corresponding to each port in the multi-port solid-state transformer;

[0007] The DC bus voltage of the multi-port solid-state transformer is collected, and the bus voltage level is determined based on the DC bus voltage and a preset bus voltage classification threshold.

[0008] Based on the type of the connected device and in conjunction with the preset device control strategy correspondence, the coordination control logic corresponding to each connected device is determined. The device control strategy correspondence includes the coordination control logic corresponding to different device types under different voltage levels.

[0009] Preferably, the connection device includes: photovoltaic equipment, energy storage equipment, and adjustable load equipment.

[0010] Preferably, the bus voltage grading thresholds include: four different voltage grading thresholds set based on the rated DC bus voltage, wherein two voltage grading thresholds are greater than the rated DC bus voltage, and the other two voltage grading thresholds are less than the rated DC bus voltage.

[0011] Preferably, the coordination control logic for each connected device is determined based on its type and a pre-defined device control strategy correspondence, including:

[0012] When the DC bus voltage is greater than or equal to the first voltage level threshold, the photovoltaic equipment reduces power according to the droop control mode in the preset MPP-droop control logic, the energy storage equipment charges according to the maximum current threshold, and the adjustable load equipment operates in full load mode, wherein the values ​​of the first voltage level threshold to the fourth voltage level threshold decrease sequentially.

[0013] When the DC bus voltage is between the first voltage grading threshold and the second voltage grading threshold, the photovoltaic equipment reduces power according to the droop control mode in the MPP-droop control logic, the energy storage equipment is charged according to the preset hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0014] When the DC bus voltage is between the second voltage level threshold and the third voltage level threshold, the photovoltaic equipment operates according to the MPPT control mode in the preset MPP-droop control logic, the energy storage equipment switches to standby mode, and the adjustable load equipment operates in full load mode.

[0015] When the DC bus voltage is between the third voltage level threshold and the fourth voltage level threshold, the photovoltaic equipment operates at the maximum power point, the energy storage equipment discharges according to the hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0016] When the DC bus voltage is less than or equal to the fourth voltage grading threshold, the photovoltaic equipment operates in the MPPT control mode of the MPP-droop control logic, the energy storage equipment discharges according to the maximum current threshold, and the adjustable load equipment is disconnected in layers.

[0017] Preferably, the MPP-droop control logic specifically comprises:

[0018]

[0019] In the formula, The reference value representing the output power and voltage derivative of a photovoltaic unit. This is the upper limit of the reference value; Indicates the droop coefficient. The DC bus voltage is... This is the rated value of the DC bus voltage.

[0020] Preferably, the layered droop control logic specifically comprises:

[0021]

[0022] In the formula, k bdp k bdi The PI parameters are for the tiered droop control of the energy storage unit. The DC bus voltage is... The rated value of the DC bus voltage. This is a reference value for the current of the energy storage device when it is operating within its normal range. The threshold values ​​are sequentially from the first voltage level threshold to the fourth voltage level threshold. This is the sag coefficient of the energy storage device. This is the maximum discharge current of the energy storage device. Let be the maximum charging current of the energy storage device, and s be the complex variable parameter of the transfer function.

[0023] Meanwhile, a second aspect of this application provides a multi-port solid-state transformer coordination control device, comprising:

[0024] The port device determination unit is used to determine the connection device corresponding to each port in the multi-port solid-state transformer based on the topology information of the multi-port solid-state transformer.

[0025] The bus voltage determination unit is used to collect the DC bus voltage of the multi-port solid-state transformer and determine the bus voltage level based on the DC bus voltage and a preset bus voltage classification threshold.

[0026] A multi-port control logic matching unit is used to determine the coordination control logic corresponding to each connected device based on the type of the connected device and in conjunction with a preset device control strategy correspondence. The device control strategy correspondence includes the coordination control logic corresponding to different device types under different voltage levels.

[0027] Preferably, the connection device includes: photovoltaic equipment, energy storage equipment, and adjustable load equipment;

[0028] The bus voltage grading thresholds include four different voltage grading thresholds set based on the rated DC bus voltage, wherein two of the voltage grading thresholds are greater than the rated DC bus voltage, and the other two voltage grading thresholds are less than the rated DC bus voltage.

[0029] A third aspect of this application provides a multi-port solid-state transformer coordination control terminal, including: a memory and a processor;

[0030] The memory is used to store program code, which corresponds to the multi-port solid-state transformer coordinated control method provided in the first aspect of this application.

[0031] The processor is used to read and execute the program code to implement the multi-port solid-state transformer coordinated control method corresponding to the program code.

[0032] The fourth aspect of this application provides a computer-readable storage medium storing program code, which is read and executed by a processor to implement the multi-port solid-state transformer coordinated control method provided in the first aspect of this application.

[0033] As can be seen from the above technical solutions, this application has the following advantages:

[0034] The solution provided in this application dynamically matches the coordinated control logic of different devices by classifying equipment types and combining them with bus voltage grading thresholds. This achieves synergistic optimization of photovoltaic power generation maximum power tracking, energy storage charging and discharging power regulation, and load grading switching, ensuring that photovoltaic, energy storage, and load equipment form optimal coordination under different operating conditions. It has the advantages of improving the power supply reliability and power quality of multi-energy systems and avoiding the risks of DC bus voltage exceeding limits and equipment overload. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart illustrating an embodiment of a multi-port solid-state transformer coordinated control method provided in this application.

[0037] Figure 2 This is a schematic diagram illustrating the operating characteristics of the multi-port solid-state transformer coordinated control method provided in this application.

[0038] Figure 3 The block diagram of adjustable load hierarchical switching control in a multi-port solid-state transformer coordinated control method provided in this application is shown.

[0039] Figure 4This document describes the changes in power of important and adjustable loads based on the multi-port solid-state transformer coordinated control method provided in this application.

[0040] Figure 5 This is a schematic diagram of the DC bus voltage waveform measured based on the multi-port solid-state transformer coordinated control method provided in this application.

[0041] Figure 6 This is a schematic diagram of an embodiment of a multi-port solid-state transformer coordination control device provided in this application.

[0042] Figure 7 This is a schematic diagram of the structure of an embodiment of a multi-port solid-state transformer coordination control terminal provided in this application. Detailed Implementation

[0043] In existing technologies, as the proportion of new energy sources connected to the power system continues to increase, the energy interaction mode of the power system is gradually changing from the traditional one-to-many unidirectional power supply mode to a many-to-many mode of multi-directional interaction between power sources, grids, loads, and storage. This makes energy flow paths and power distribution relationships increasingly complex. Multi-port solid-state transformers, as core power electronic equipment for achieving coordinated management and control of distributed new energy sources, energy storage devices, and load resources, directly determine the operational stability and energy utilization efficiency of the distribution network based on the rationality of their coordinated control strategies. Currently, the coordination control strategies for existing multi-port solid-state transformers are mainly divided into two categories: centralized and distributed. The centralized control strategy relies on real-time interconnection and communication between the central controller and each port device. The central node makes unified decisions and issues control commands. This mode not only suffers from complex communication links, large communication delays, and heavy communication burdens, but is also prone to failure of the entire control system due to a single point of failure in the decision center, resulting in a high risk of failure. Although the distributed control strategy abandons the reliance on centralized communication and adopts an independent decision-making method for each port local controller, it does not establish a unified coordination mechanism between the port devices. The control objective of system power balance is distributed to different controllers. Under complex operating conditions such as islanded operation and power surges, the adjustment actions of each device lack coordination, which can easily lead to problems such as misaligned adjustment timing and power compensation.

[0044] Particularly crucial is that when the AC power grid is disconnected from the multi-port solid-state transformer due to faults, maintenance, or other reasons, the multi-port solid-state transformer will enter the island operation state. At this time, it needs to independently undertake the power dispatching and power balance tasks within the island area, effectively regulate the power flow between photovoltaic, energy storage, and load, ensure the stable and reliable power supply within the island area, and prevent problems such as DC bus voltage instability, equipment overload, and load power supply interruption caused by power imbalance. However, in actual engineering scenarios, the coordinated control technology of multi-port solid-state transformers is still in its infancy. Existing strategies are difficult to effectively decouple and balance the coupling relationship among the source, storage, and load, and cannot achieve the precise coordinated operation of the three. Ultimately, there are technical problems such as poor reliability, low power quality, and easy voltage over-limit in the coordinated control of multi-port solid-state transformers, severely restricting its engineering application in new energy distribution networks.

[0045] To solve the problems existing in the above-mentioned prior art, the R & D personnel of this application found through a large amount of theoretical analysis, simulation verification, and engineering tests that the change in the DC bus voltage of the multi-port solid-state transformer can directly and accurately reflect the power balance state inside the island system: too high DC bus voltage usually corresponds to a system power surplus caused by excessive photovoltaic output and insufficient load power demand; too low DC bus voltage usually corresponds to a system power deficit caused by insufficient photovoltaic output and sudden increase in load power demand. Based on this core technical discovery, the R & D personnel proposed to hierarchically divide the DC bus voltage, match a corresponding source-storage-load device control combination strategy for each voltage level, and trigger the preset coordinated control logic using the local detection signal of the DC bus voltage to achieve the autonomous and coordinated adjustment of each port device. This design idea fundamentally avoids the dependence on complex interconnection communication and can complete the linkage control of multiple devices through local voltage detection. It not only retains the high reliability of distributed control but also achieves the global coordination effect similar to centralized control, effectively solving the technical problem of low reliability in the existing coordinated control of multi-port solid-state transformers.

[0046] To make the invention purpose, features, and advantages of this application more obvious and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the embodiments described below are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0047] First, a detailed description of an embodiment of a coordinated control method for a multi-port solid-state transformer provided by this application is as follows:

[0048] Please refer to Figure 1This application provides a multi-port solid-state transformer coordinated control method, comprising:

[0049] Step 101: Based on the topology information of the multi-port solid-state transformer, determine the connection devices corresponding to each port in the multi-port solid-state transformer;

[0050] Step 102: Collect the DC bus voltage of the multi-port solid-state transformer, and determine the bus voltage level based on the DC bus voltage and the preset bus voltage classification threshold.

[0051] Step 103: Based on the type of connected device and the pre-defined device control strategy correspondence, determine the coordination control logic corresponding to each connected device;

[0052] The equipment control strategy correspondence includes the coordination control logic corresponding to different equipment types under different voltage levels.

[0053] The topology information mentioned in this step refers to the connection relationships of each electrical port of the multi-port solid-state transformer, the types of connected devices, the core electrical parameters of the devices, and the electrical connection methods between the devices and the transformer. This information can be obtained through the equipment configuration database of the distribution network, configuration system information, or by identifying the real-time electrical parameter detection results of each port. Its core function is to accurately identify the connection locations of different types of devices such as photovoltaics, energy storage, and adjustable loads, providing a basis for subsequent differentiated regulation. The DC bus voltage grading threshold is a set of multiple critical values ​​based on the rated DC bus voltage of the multi-port solid-state transformer, combined with the device withstand voltage characteristics, the voltage fluctuation standards of the power grid operation, and the regulation response characteristics of the source-load storage devices. These critical values ​​divide the DC bus voltage into multiple voltage level ranges, each corresponding to different power imbalance states and power regulation requirements of the system. The equipment control strategy correspondence is a pre-established multi-dimensional logical mapping table that encodes and matches different equipment types such as photovoltaic, energy storage, and adjustable loads with the control modes and adjustment parameters under each DC bus voltage range. For example, it configures the power reduction mode in the high voltage range and the maximum power point tracking mode in the normal voltage range for photovoltaic equipment, ensuring that each device can perform matching adjustment actions under different voltage conditions.

[0054] Specifically, in practical engineering applications, the first step is to accurately identify the types of connected devices at each electrical port using the local configuration identification module of the multi-port solid-state transformer or the equipment configuration information in the distribution network backend. For example, this identifies a photovoltaic inverter and photovoltaic array connected to an AC port, an energy storage converter and energy storage battery pack connected to a DC port, and an adjustable load intelligent controller and various electrical loads connected to a load port. Then, a high-precision voltage sensor installed on the DC bus performs real-time acquisition and filtering of the DC bus voltage to eliminate the influence of detection noise on voltage judgment. The processed real-time voltage value is compared with multiple preset bus voltage classification thresholds to determine the current DC bus voltage level range, classifying the system as having severe power surplus, slight power surplus, power balance, slight power deficit, or severe power deficit. Finally, based on the determined voltage level, the corresponding coordination control logic and adjustment parameters for each device type are retrieved from the local controller's preset database, driving each device to perform corresponding adjustment actions: when the voltage exceeds the first threshold, the photovoltaic device immediately switches to droop control mode to actively reduce output power, the energy storage device charges at the maximum allowable current to absorb excess energy, and the adjustable load maintains full-load operation to maximize the consumption of the system's surplus power; when the voltage is in the middle range of slight overvoltage, the energy storage device switches from constant current charging to layered droop control mode to achieve adaptive and smooth adjustment of the charging rate, avoiding a sudden drop in DC bus voltage due to sudden changes in charging current. The entire control process does not rely on commands from the central controller, nor does it require interconnection communication between devices. It can trigger the preset coordinated control strategy solely through the local detection signal of the DC bus voltage, achieving autonomous coordination of multi-port devices.

[0055] This solution establishes an implicit collaborative regulation mechanism for source-load storage devices through a voltage tiering mechanism. It retains the high reliability of distributed control—no communication dependency and resistance to single-point failures—while achieving global power balance and device coordination effects similar to centralized control. For example, in islanded operation, when photovoltaic output increases sharply due to sudden changes in sunlight, causing a rapid rise in DC bus voltage, the system can automatically initiate multi-device joint regulation actions—photovoltaic power reduction and energy storage charging enhancement—based on voltage tier changes. This avoids equipment damage and system instability caused by overload regulation of a single device. Through this technical solution, precise autonomous coordination of multi-port devices can be achieved without interconnection communication, effectively solving the power imbalance problem during islanded operation. Simultaneously, by triggering differentiated control strategies through voltage tiering, it ensures optimal coordination between photovoltaic, energy storage, and load devices under different operating conditions. For instance, in the event of severe overvoltage, photovoltaic power reduction and full energy storage charging are initiated simultaneously, quickly absorbing excess system power, restoring voltage stability, and improving the power supply reliability and power quality of the multi-energy system.

[0056] More specifically, the connection equipment mentioned in this application includes photovoltaic equipment, energy storage equipment, and adjustable load equipment. These three types of equipment serve as distributed generation units, energy storage and compensation units, and load regulation units in the islanded system, respectively, forming the core carrier for coordinated regulation of source, storage, and load.

[0057] Photovoltaic equipment refers to power generation units that convert solar energy into electrical energy. Specifically, it can be implemented using a combination of photovoltaic arrays and inverters, used to inject renewable energy power into the DC bus. Energy storage equipment refers to electrical energy storage units with charging and discharging capabilities. Specifically, it can be implemented using a combination of lithium-ion battery packs and bidirectional converters, used to absorb or release electrical energy based on the bus voltage status. Adjustable load equipment refers to power consumption units with adjustable power. Specifically, it can be implemented using intelligent load controllers, used to adjust the operating status or perform tiered load shedding operations based on the bus voltage level.

[0058] Specifically, when determining the connection equipment corresponding to each port of the multi-port solid-state transformer, this application precisely classifies the equipment types into three categories: photovoltaic equipment, energy storage equipment, and adjustable load equipment. The core design intention is to establish differentiated control strategies and adjustment sequences based on the technical characteristics and functional positioning of these three types of equipment, avoiding overlapping or conflicting adjustment actions of different equipment and improving the overall control coordination of the system. When the voltage sensor detects fluctuations in the DC bus voltage, the three types of equipment will execute matching adjustment actions according to their own technical characteristics: photovoltaic equipment will flexibly switch between maximum power point tracking (MPPT) mode and power reduction droop control mode based on irradiance conditions and voltage levels, ensuring the utilization rate of renewable energy while avoiding voltage over-limit caused by excessive photovoltaic output; energy storage equipment will switch between standby, constant current charging / discharging, and tiered droop charging / discharging modes based on voltage levels to achieve rapid energy storage and compensation, serving as the core adjustment unit for system power balance; adjustable load equipment will adjust power demand from the power consumption side by adjusting operating power or cutting off loads in stages according to priority, serving as the last line of defense for system power balance. The three types of equipment form a complementary, tiered control mechanism. For example, when the bus voltage is too high, the photovoltaic equipment actively reduces its output, the energy storage equipment absorbs excess power, and the adjustable load maintains full-load operation, simultaneously absorbing the system's surplus power from the generation side, energy storage side, and load side. When the voltage is too low, the energy storage equipment releases its stored power, and the adjustable load cuts off secondary loads in stages, quickly compensating for the power deficit from the energy storage side and the load side, raising the bus voltage, and ultimately achieving stable control of the DC bus voltage.

[0059] This solution, through precise classification and differentiated control of equipment types, enables photovoltaic, energy storage, and load to execute control actions matched to their respective technical characteristics, avoiding overlapping control commands and equipment adjustment conflicts, and significantly improving the system's control coordination. At the same time, the tiered response mechanism formed by the three types of equipment can achieve comprehensive regulation of system power from the three dimensions of power generation, energy storage, and load, effectively maintaining the stability of DC bus voltage, avoiding voltage overruns and equipment overload risks, and significantly improving the reliability of power distribution and system operation stability of multi-port solid-state transformers in islanded operation.

[0060] Furthermore, this application proposes a bus voltage grading threshold system comprising four different voltage grading thresholds based on the rated DC bus voltage, wherein two of the voltage grading thresholds are greater than the rated DC bus voltage, and the other two are less than the rated DC bus voltage. The first to fourth voltage grading thresholds can be listed sequentially as follows: Their values ​​can be set to 1.04 respectively. 1.015 0.985 0.96 , where u dlN The rated value of the DC bus voltage is used to divide the voltage into five ranges using these four threshold values.

[0061] Based on the above four bus voltage grading thresholds, this application further proposes to determine the corresponding coordinated control logic for each connected device according to the type of connected device and the preset device control strategy correspondence. Specifically, when the DC bus voltage is greater than or equal to the first voltage grading threshold, the photovoltaic device reduces power according to the droop control mode in the preset MPP-droop control logic, the energy storage device charges according to the maximum current threshold, and the adjustable load device operates in full-load mode. Here, the first voltage grading threshold is the voltage grading threshold with the largest value. When the DC bus voltage is between the first voltage grading threshold and the second voltage grading threshold, the photovoltaic device reduces power according to the droop control mode in the MPP-droop control logic, the energy storage device charges according to the preset tiered droop control logic, and the adjustable load device operates in full-load mode. The system operates in a specific mode, where the second voltage grading threshold is second only to the first voltage grading threshold. When the DC bus voltage is between the second and third voltage grading thresholds, the photovoltaic equipment operates according to the MPPT control mode in the preset MPP-droop control logic, the energy storage equipment switches to standby mode, and the adjustable load equipment operates in full-load mode. When the DC bus voltage is between the third and fourth voltage grading thresholds, the photovoltaic equipment operates at its maximum power point, the energy storage equipment discharges according to the tiered droop control logic, and the adjustable load equipment operates in full-load mode. When the DC bus voltage is less than or equal to the fourth voltage grading threshold, the photovoltaic equipment operates according to the MPPT control mode in the MPP-droop control logic, the energy storage equipment discharges according to the maximum current threshold, and the adjustable load equipment is tiered disconnected.

[0062] Among them, MPP-droop control logic refers to a control method that dynamically adjusts the output power of photovoltaic equipment through a droop coefficient. Specifically, it is achieved by switching between droop control mode and MPPT control mode. When the bus voltage exceeds a threshold, it switches to droop control mode to actively reduce power and prevent the bus voltage from rising continuously. Layered droop control logic refers to a control method that adjusts the charging and discharging current of energy storage equipment in stages based on the bus voltage deviation range. Specifically, it can be implemented using a combination of PI parameters and droop coefficients. Layered control avoids frequent switching of operating states of energy storage equipment during voltage fluctuations. Layered shelving refers to gradually cutting off the operation of adjustable load equipment according to the degree of voltage drop. Specifically, it can be implemented using priority sorting or load grouping, prioritizing the shelving of non-critical loads to maintain bus voltage stability.

[0063] Specifically, in actual operation, the coordinated adjustment process of equipment in each voltage range is as follows:

[0064] When the DC bus voltage is higher than the first voltage level threshold, the photovoltaic output of the system is significantly excessive and the power surplus is significant. At this time, the photovoltaic equipment actively reduces the output power through the droop control algorithm. The reduction range is determined by the droop coefficient. The energy storage equipment absorbs the excess power of the system with the maximum charging current allowed by the equipment. The adjustable load keeps the full load operation to maximize the consumption of surplus power. The three work together to quickly absorb the system surplus from the generation side, energy storage side and load side, and suppress the continuous rise of voltage.

[0065] When the DC bus voltage drops back to between the first and second thresholds, the system power has a slight surplus. At this time, the photovoltaic equipment is still in the power reduction droop control state to continuously suppress the voltage rise. The energy storage equipment switches from constant current charging to layered droop charging mode, and adaptively adjusts the charging current according to the degree of voltage deviation to slow down the charging speed and avoid the DC bus voltage from dropping suddenly due to the sudden change in charging current. The adjustable load still maintains full load operation.

[0066] When the DC bus voltage is within the normal range and the system power is basically balanced, the photovoltaic equipment resumes the maximum power point tracking (MPPT) mode to maximize the use of solar energy resources. The energy storage equipment enters standby mode, shuts down the charging and discharging circuit to reduce energy loss, and the adjustable load maintains full-load operation to meet normal power demand.

[0067] When the DC bus voltage is lower than the third threshold but higher than the fourth threshold, the system power is slightly short. At this time, the photovoltaic equipment maintains the maximum power point operation to maximize the output of electrical energy. The energy storage equipment starts the tiered droop discharge mode and adaptively adjusts the discharge current according to the degree of voltage deviation to achieve smooth power compensation and avoid voltage oscillation caused by sudden changes in discharge current. The adjustable load maintains full-load operation to meet the power demand.

[0068] When the DC bus voltage is lower than the fourth voltage level threshold, the system power is significantly insufficient, and even full photovoltaic power generation cannot meet the load demand. At this time, the energy storage device injects electrical energy into the bus at the maximum discharge current allowed by the device to maximize the compensation for the system power shortage. At the same time, the adjustable load device performs tiered disconnection operation according to the power consumption priority, gradually disconnecting secondary loads, quickly reducing the system power demand, preventing the DC bus voltage from continuously dropping, and ensuring the continuous power supply to important loads.

[0069] This solution establishes a pre-defined voltage grading threshold and a corresponding equipment control strategy, configuring targeted source-load storage device collaborative control combinations for each voltage range. This enables photovoltaic, energy storage, and load devices to perform differentiated collaborative actions within different voltage ranges. For example, when the voltage is too high, photovoltaic output is simultaneously reduced while the energy storage charging rate is increased; when the voltage is too low, energy storage discharge is prioritized to compensate for the power deficit; and load is only disconnected in cases of severe undervoltage. This forms a closed-loop control mechanism involving multiple devices, achieving precise, rapid, and stable control of the DC bus voltage. Through this technical solution, refined collaborative control of source-load storage devices by multi-port solid-state transformers can be achieved in islanded operation scenarios, effectively solving the voltage instability problem caused by uncoordinated equipment actions in existing technologies. For example, when the bus voltage drops below the fourth threshold due to a sudden increase in load, the energy storage device supports the voltage with its maximum discharge current, while simultaneously cascading adjustable loads to compensate for the power deficit from both the energy storage and load sides, preventing overload of a single device or voltage collapse. When photovoltaic output exceeds the first threshold due to a sudden change in sunlight, the photovoltaic and energy storage devices synchronously adjust their operating modes, with the photovoltaic system actively reducing power and the energy storage system fully charging and absorbing the load. This effectively suppresses voltage rise and prevents the energy storage charging current from exceeding the safe range, ultimately achieving stable control of the DC bus voltage in the islanded system and improving the operational reliability of the islanded system. Furthermore, the MPP-droop control logic provided in this application is specifically expressed as follows:

[0070]

[0071] In the formula, The reference value representing the output power and voltage derivative of a photovoltaic unit. This is the upper limit of the reference value; Indicates the droop coefficient. This is the DC bus voltage. This is the rated value of the DC bus voltage.

[0072] The reference values ​​for the output power and voltage derivative of the photovoltaic unit refer to the power reference values ​​output by the photovoltaic equipment in MPPT control mode or droop control mode. Specifically, these values ​​can be calculated by real-time measurement of the DC bus voltage and combined with preset rated values, and are used to dynamically adjust the power output of the photovoltaic equipment. The droop coefficient is a parameter used to adjust the slope of the photovoltaic equipment's power change with the DC bus voltage. Specifically, it can be set using empirical values ​​based on system stability requirements or simulation optimization results. This coefficient balances the power adjustment speed and system stability. The rated value of the DC bus voltage refers to the reference value of the bus voltage of the multi-port solid-state transformer under normal operating conditions. Specifically, it can be set according to equipment specifications or grid operation standards, serving as a key benchmark for determining the voltage level.

[0073] Specifically, when the DC bus voltage is below the rated value, the photovoltaic (PV) equipment operates in maximum power point tracking (MPPT) mode, where the output power reference value remains at the upper limit to ensure maximum PV power generation efficiency. When the DC bus voltage reaches or exceeds the rated value, the PV equipment switches to droop control mode, where the output power reference value decreases linearly with the voltage increase, and the reduction magnitude is determined by the droop coefficient. Through this logic, the PV equipment can dynamically adjust its power output according to real-time changes in the bus voltage, avoiding system instability due to excessive voltage. Simultaneously, it coordinates with the control strategies of other connected devices to maintain power balance in islanded operation.

[0074] More specifically, the construction method of the above MPP-droop control logic can be seen in the following example:

[0075] First, based on traditional MPPT control, an MPPT constant power point control strategy is set:

[0076] The photovoltaic array module is composed of photovoltaic cells connected in series and parallel. It uses the photovoltaic effect to directly convert solar energy into DC power. The MPPT module tracks the output voltage and current of the photovoltaic array and calculates the voltage value at maximum power output by combining temperature parameters and other factors. Based on this, it calculates the duty cycle of the gate control signal of the Boost module, thereby controlling the output voltage of the Boost module to achieve maximum power output.

[0077]

[0078] Among them: I sc U is the short-circuit current of the photovoltaic panel. oc Open-circuit voltage of photovoltaic panel; I m U m These are the maximum power point current and maximum power point voltage of the photovoltaic panel, respectively; S ref For reference light intensity. sc U oc I m and U m These four parameters are provided by the photovoltaic panel manufacturer, and the short-circuit current I of the photovoltaic cell can be calculated using the formula. sc ′、Maximum power current I m ′、Open circuit voltage U oc ′ and maximum power voltage U m ′

[0079] Then, the traditional MPPT control is combined with droop control to set up an MPP-droop control strategy based on DC bus voltage stratification:

[0080] like Figure 2 As shown in part (a), when the DC bus voltage Less than its rated value At this time, the photovoltaic unit uses MPPT control to output maximum power to compensate for the power demand of the load. When the DC bus voltage is greater than the threshold u dlu When this happens, the photovoltaic unit switches to droop control, reducing its output power to prevent further increase in bus voltage.

[0081] In MPP-droop control, the power-voltage characteristic equation of the photovoltaic unit is:

[0082]

[0083] In the formula: This represents a reference value indicating the output power of a photovoltaic unit and its voltage derivative. Its upper limit is set to 0. When its value is 0, MPPT operation mode can be achieved. This represents the droop coefficient, which takes a value greater than 0.

[0084] In order to obtain The value of is calculated using the incremental conductance method shown in the following formula:

[0085]

[0086] In the formula: For the slight increase in the conductance of the photovoltaic cell, when A value close to 0 will lead to incorrect calculation results, therefore, when calculating... The result is to limit the amplitude in order to obtain a reasonable and reliable result. Calculation results.

[0087] Therefore, when When the value is 0, the characteristic equation for MPP-droop can be further simplified to:

[0088] .

[0089] Furthermore, the layered droop control logic mentioned in the above embodiments is specifically expressed as follows:

[0090]

[0091] In the formula, k bdp k bdi The PI parameters are for the tiered droop control of the energy storage unit. This is the DC bus voltage. This is the rated value of the DC bus voltage. This is a reference value for the current of the energy storage device when it is operating within its normal range. The threshold values ​​are sequentially from the first voltage level threshold to the fourth voltage level threshold. This is the sag coefficient of the energy storage device. This is the maximum discharge current of the energy storage device. Let be the maximum charging current of the energy storage device, and s be the complex variable parameter of the transfer function.

[0092] It should be noted that droop control uses the low-voltage DC bus voltage as the controlled object, allowing the energy storage unit to switch between charging and discharging modes as needed, thus achieving stable control of the DC bus voltage. However, when there is a significant DC bus power deficit or surplus, the energy storage unit operating according to the traditional droop characteristic curve cannot adjust its charging and discharging power in a timely manner, which may lead to a sharp deterioration of the DC bus voltage. Therefore, a layered droop control strategy for the energy storage unit is implemented.

[0093] As can be seen from the above expression, such as Figure 2 As shown in part (b), the energy storage unit employs layered droop control when the DC bus voltage is at [u dll , u dlu When the DC bus voltage is within the specified range, the energy storage unit is in standby mode. dlu At this time, the energy storage unit switches to charging mode, in [u dlu , u dlm Within the voltage range of [u], the DC bus voltage increases relatively little, and the energy storage unit operates in a droop charging state. The charging current increases with the rise of the DC bus voltage, while when the DC bus voltage exceeds [u]... dlm At this time, there is a severe energy surplus at the DC bus, and the energy storage unit absorbs the unbalanced power with its maximum charging current. To avoid repeated switching of the energy storage unit's operating state, it only operates when the DC bus voltage drops to u. dlN Only then does the energy storage unit switch back to standby mode. Similarly, when a power deficit occurs at the DC bus, the DC bus voltage drops to [u dln , u dll When the voltage is within the specified range, the energy storage unit switches to droop discharge mode, and its discharge current increases continuously as the DC bus voltage decreases. When the DC bus voltage drops to u... dln When the voltage drops below a certain level, the energy storage unit compensates for the power deficit with the maximum discharge current. When the DC bus voltage rises back to u... dlN At this time, the operating point of the energy storage unit switches back to standby. Furthermore, the operating state of the battery energy storage is related to its SOC (State of Charge). b Closely related, SOC b The system must be shut down if the voltage is too high or too low. This applies when the battery is in charging mode and the SOC (State of Charge) is... b When the voltage exceeds the upper limit, the energy storage unit will enter standby mode and can only be put back into operation when a power deficit occurs at the DC bus. In this situation, to avoid repeated switching between discharge and standby modes, it is stipulated that the unit can only operate when the DC bus voltage is below u. dln At that time, the energy storage unit switches to constant current discharge mode. Similarly, when the battery's state of charge (SOC) is reached... bWhen the voltage is below the lower limit, the battery enters standby mode. It will only resume operation when the bus voltage is above u. dlm Only then does the energy storage unit begin constant current charging.

[0094] More specifically, for details regarding the tiered switching control of adjustable load equipment, please refer to the following example:

[0095] like Figure 2 Part (c) and Figure 3 As shown, under normal operating conditions of a multi-port solid-state transformer, all loads should be fully loaded to meet the electricity demand of users; this is the basic principle of load regulation. However, since the output power of photovoltaic units is limited by natural conditions such as sunlight and temperature, and the discharge power of energy storage units is limited by battery capacity and rated power of equipment, both have an upper limit on their output power. When the maximum output power P of the photovoltaic unit... phm With the energy storage battery's maximum discharge power P bdm The sum is still less than the total power required by the system's load, that is , where P il For the power of a non-adjustable load, P ml When the power of the adjustable load is at a certain level, the power at the DC bus cannot be balanced, and the DC capacitor will continue to discharge, resulting in a continuous decrease in the DC bus voltage. If measures are not taken in time, it will cause serious problems such as voltage collapse and load outage.

[0096] To ensure the stability of the bus voltage while prioritizing the power demand of critical loads, this application proposes an adjustable load tiered switching control strategy. This strategy uses the DC bus voltage as the core judgment criterion. When the DC bus voltage drops significantly and the power compensation of photovoltaic and energy storage cannot meet the load demand, the system power demand is quickly reduced by tiered switching of adjustable loads to maintain power balance.

[0097] When the DC bus voltage is lower than u dln At that time, adjustable loads are disconnected one by one through the control of the circuit breaker, wherein P mlN The rated power of the adjustable load is set to simplify the analysis. The power is The time interval for each load shearing is Until the DC bus voltage is greater than u after the adjustable load i is removed. dln Until then. To avoid repeated switching of adjustable loads, the low-voltage DC bus voltage should be greater than u after the load is removed. dll At that time, the circuit breakers that have been disconnected from the adjustable load are closed one by one to put them back into operation until all disconnected loads are put back into operation.

[0098] To more clearly demonstrate the technical effects of the present application's technical solution, this embodiment also provides a test example based on the coordination and control strategy provided in the present application, as follows:

[0099] First, it should be noted that the coordinated control parameter configuration for multi-port solid-state transformers under islanded conditions is shown in Table 1 below:

[0100]

[0101] The photovoltaic units are set to operate at optimal irradiance and operating temperature, with an output power of 400 kW. The initial operating power of the critical load is 250 kW, and the initial power of the adjustable load is 150 kW. At t=0.8 s, the operating power of the critical load is reduced to 150 kW, while the adjustable load is completely cut off. At t=1.2 s, the critical load and the adjustable load of 250 kW are put into operation.

[0102] When the energy storage unit is in standby mode, the DC bus voltage rises to 1085.5 V after the operating power of critical and adjustable loads decreases, but drops to 959.6 V after the load is reconnected, exceeding the maximum fluctuation range of the bus voltage. When the energy storage unit is operational and the multi-port solid-state transformer uses only the basic control strategy, the DC bus voltage rises to 1061.1 V and drops to 976.8 V after load disconnection and reconnection, respectively. The maximum DC bus voltage still does not meet the stability requirements of the multi-port solid-state transformer. However, when the multi-port solid-state transformer adopts a coordinated control strategy, the DC bus voltage is stably limited to 1009.5 V after load disconnection and rises to 998.4 V after load reconnection, with minimal fluctuation. Compared with the basic control strategy, the voltage suppression rate and rise rate are 4.9% and 2.2%, respectively, meeting the stable operation requirements of the multi-port solid-state transformer.

[0103] like Figure 4 and Figure 5 As shown, where, Figure 4Part (a) represents the change in the critical load, and part (b) represents the change in the adjustable load power. When the load is cut off at t=0.8 s, the energy storage unit starts charging to absorb the power redundancy at the DC bus. Under the basic control strategy, the battery SOC is charged from the initial value of 70% to 70.006%, and the charging power is 68.96 kW. The photovoltaic unit always works at the maximum power point, outputting 400 kW of power. However, when the coordinated control strategy is adopted, the energy storage unit charges faster, and the battery SOC is charged from the initial value of 70% to 70.01%. The maximum charging current is used to absorb the energy redundancy, and the charging power is 108 kW, which is 56.6% higher than the basic control strategy. The output of the photovoltaic unit is reduced from 400 kW to 360.4 kW to avoid the power redundancy at the DC bus. After the load is applied at t=1.2 s, the DC bus voltage decreases, and the energy storage unit begins to discharge. Under the basic control strategy, the SOC of the energy storage battery discharges from 70.006% to 70.004%, with a discharge power of 40.5 kW. Since u dln ≤u dl dll The energy storage unit under coordinated control operates in droop discharge mode, with its SOC discharging from 70.01% to 70.003%, and the maximum discharge power is 117.3 kW, which is 2.9 times that under the basic control strategy. The photovoltaic units under both the basic control strategy and the coordinated control strategy operate in MPPT mode, providing energy with a power of 400 kW.

[0104] It can be seen that under continuous load switching, the multi-port solid-state transformer under the basic control strategy cannot effectively guarantee the stability of the DC bus voltage. However, the coordinated control strategy proposed in this paper can efficiently guarantee the power balance at the DC bus and maintain the bus voltage stable within the range of 0.998 pu to 1.009 pu. Under the basic control strategy, power redundancy occurs at the DC bus when the load power decreases. The photovoltaic units operating in MPPT mode exacerbate the power redundancy at the bus. The energy storage unit under constant voltage control charges slowly. Although the bus voltage is lower than that when the energy storage is in standby mode, it is still higher than its maximum threshold. After the load is applied, the energy storage unit discharges slowly. Although it raises the DC bus voltage to some extent, it still deviates significantly from its rated value. Under the coordinated control strategy, after the load power decreases, the photovoltaic unit switches to droop mode to reduce output by 9.9%, while the energy storage unit quickly switches to maximum current charging, which increases the compensation rate for power imbalance by up to 56.6%, causing the bus voltage to rise slightly. When the load power demand increases, the energy storage unit switches its operating point in a timely manner according to the droop control curve, and the maximum discharge power reaches 115 kW, effectively raising the bus voltage.

[0105] ​The above is a detailed description of an embodiment of a multi-port solid-state transformer coordinated control method provided in this application. The following is a detailed description of an embodiment of a multi-port solid-state transformer coordinated control device provided in this application.

[0106] Please see Figure 6 This application provides a multi-port solid-state transformer coordination control device, comprising:

[0107] The port device determination unit 201 is used to determine the connection device corresponding to each port in the multi-port solid-state transformer based on the topology information of the multi-port solid-state transformer.

[0108] The bus voltage determination unit 202 is used to collect the DC bus voltage of the multi-port solid-state transformer and determine the bus voltage level based on the DC bus voltage and a preset bus voltage classification threshold.

[0109] The multi-port control logic matching unit 203 is used to determine the coordination control logic corresponding to each connected device based on the type of connected device and the preset device control strategy correspondence. The device control strategy correspondence includes the coordination control logic corresponding to different device types under different voltage levels.

[0110] Furthermore, the connecting devices include: photovoltaic equipment, energy storage equipment, and adjustable load equipment;

[0111] The bus voltage grading thresholds include four different voltage grading thresholds set based on the rated DC bus voltage, where two voltage grading thresholds are greater than the rated DC bus voltage and the other two voltage grading thresholds are less than the rated DC bus voltage.

[0112] In some embodiments, determining the coordination control logic corresponding to each connected device based on the type of the connected device and a preset device control strategy correspondence includes:

[0113] When the DC bus voltage is greater than or equal to the first voltage level threshold, the photovoltaic equipment reduces power according to the droop control mode in the preset MPP-droop control logic, the energy storage equipment charges according to the maximum current threshold, and the adjustable load equipment operates in full load mode, wherein the values ​​of the first voltage level threshold to the fourth voltage level threshold decrease sequentially.

[0114] When the DC bus voltage is between the first voltage grading threshold and the second voltage grading threshold, the photovoltaic equipment reduces power according to the droop control mode in the MPP-droop control logic, the energy storage equipment is charged according to the preset hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0115] When the DC bus voltage is between the second voltage level threshold and the third voltage level threshold, the photovoltaic equipment operates according to the MPPT control mode in the preset MPP-droop control logic, the energy storage equipment switches to standby mode, and the adjustable load equipment operates in full load mode.

[0116] When the DC bus voltage is between the third voltage level threshold and the fourth voltage level threshold, the photovoltaic equipment operates at the maximum power point, the energy storage equipment discharges according to the hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0117] When the DC bus voltage is less than or equal to the fourth voltage grading threshold, the photovoltaic equipment operates in the MPPT control mode of the MPP-droop control logic, the energy storage equipment discharges according to the maximum current threshold, and the adjustable load equipment is disconnected in layers.

[0118] In some embodiments, the MPP-droop control logic specifically includes:

[0119]

[0120] In the formula, The reference value representing the output power and voltage derivative of a photovoltaic unit. This is the upper limit of the reference value; Indicates the droop coefficient. The DC bus voltage is... This is the rated value of the DC bus voltage.

[0121] In some embodiments, the layered droop control logic specifically includes:

[0122]

[0123] In the formula, k bdp k bdi The PI parameters are for the tiered droop control of the energy storage unit. The DC bus voltage is... The rated value of the DC bus voltage. This is a reference value for the current of the energy storage device when it is operating within its normal range. The threshold values ​​are sequentially from the first voltage level threshold to the fourth voltage level threshold. This is the sag coefficient of the energy storage device. This is the maximum discharge current of the energy storage device. Let be the maximum charging current of the energy storage device, and s be the complex variable parameter of the transfer function.

[0124] Furthermore, this application provides detailed descriptions of embodiments of a multi-port solid-state transformer coordination control terminal and a computer-readable storage medium, as follows:

[0125] like Figure 7 As shown, a third aspect of this application provides a multi-port solid-state transformer coordination control terminal, including a memory 33 and a processor 31, wherein the memory 33 and the processor 31 can be connected via a communication bus 34;

[0126] The memory 33 is used to store program code, which corresponds to the multi-port solid-state transformer coordinated control method provided in the first aspect of this application.

[0127] The processor 31 is used to read and execute program code to implement the multi-port solid-state transformer coordinated control method corresponding to the program code.

[0128] The implementation carriers of the terminal include, but are not limited to: personal computers, industrial computers, servers, and embedded electronic devices.

[0129] More specifically, the multi-port solid-state transformer coordinated control method corresponding to the program code mentioned in this embodiment is detailed as follows:

[0130] Based on the topology information of the multi-port solid-state transformer, determine the connection device corresponding to each port in the multi-port solid-state transformer;

[0131] The DC bus voltage of the multi-port solid-state transformer is collected, and the bus voltage level is determined based on the DC bus voltage and a preset bus voltage classification threshold.

[0132] Based on the type of the connected device and in conjunction with the preset device control strategy correspondence, the coordination control logic corresponding to each connected device is determined. The device control strategy correspondence includes the coordination control logic corresponding to different device types under different voltage levels.

[0133] In some embodiments, the connection device includes: a photovoltaic device, an energy storage device, and an adjustable load device.

[0134] In some embodiments, the bus voltage grading thresholds include: four different voltage grading thresholds set based on the DC bus voltage rating, wherein two voltage grading thresholds are greater than the DC bus voltage rating, and the other two voltage grading thresholds are less than the DC bus voltage rating.

[0135] In some embodiments, determining the coordination control logic corresponding to each connected device based on the type of the connected device and a preset device control strategy correspondence includes:

[0136] When the DC bus voltage is greater than or equal to the first voltage level threshold, the photovoltaic equipment reduces power according to the droop control mode in the preset MPP-droop control logic, the energy storage equipment charges according to the maximum current threshold, and the adjustable load equipment operates in full load mode, wherein the values ​​of the first voltage level threshold to the fourth voltage level threshold decrease sequentially.

[0137] When the DC bus voltage is between the first voltage grading threshold and the second voltage grading threshold, the photovoltaic equipment reduces power according to the droop control mode in the MPP-droop control logic, the energy storage equipment is charged according to the preset hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0138] When the DC bus voltage is between the second voltage level threshold and the third voltage level threshold, the photovoltaic equipment operates according to the MPPT control mode in the preset MPP-droop control logic, the energy storage equipment switches to standby mode, and the adjustable load equipment operates in full load mode.

[0139] When the DC bus voltage is between the third voltage level threshold and the fourth voltage level threshold, the photovoltaic equipment operates at the maximum power point, the energy storage equipment discharges according to the hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0140] When the DC bus voltage is less than or equal to the fourth voltage grading threshold, the photovoltaic equipment operates in the MPPT control mode of the MPP-droop control logic, the energy storage equipment discharges according to the maximum current threshold, and the adjustable load equipment is disconnected in layers.

[0141] In some embodiments, the MPP-droop control logic specifically includes:

[0142]

[0143] In the formula, The reference value representing the output power and voltage derivative of a photovoltaic unit. This is the upper limit of the reference value; Indicates the droop coefficient. The DC bus voltage is... This is the rated value of the DC bus voltage.

[0144] In some embodiments, the layered droop control logic specifically includes:

[0145]

[0146] In the formula, kbdp k bdi The PI parameters are for the tiered droop control of the energy storage unit. The DC bus voltage is... The rated value of the DC bus voltage. This is a reference value for the current of the energy storage device when it is operating within its normal range. The threshold values ​​are sequentially from the first voltage level threshold to the fourth voltage level threshold. This is the sag coefficient of the energy storage device. This is the maximum discharge current of the energy storage device. Let be the maximum charging current of the energy storage device, and s be the complex variable parameter of the transfer function.

[0147] This application provides a computer-readable storage medium, corresponding to the memory mentioned in the above terminal embodiment. The computer-readable storage medium stores program code, which is used to be read and executed by a processor to implement the multi-port solid-state transformer coordinated control method provided in the above embodiment.

[0148] More specifically, the multi-port solid-state transformer coordinated control method corresponding to the program code mentioned in this embodiment is detailed as follows:

[0149] Based on the topology information of the multi-port solid-state transformer, determine the connection device corresponding to each port in the multi-port solid-state transformer;

[0150] The DC bus voltage of the multi-port solid-state transformer is collected, and the bus voltage level is determined based on the DC bus voltage and a preset bus voltage classification threshold.

[0151] Based on the type of the connected device and in conjunction with the preset device control strategy correspondence, the coordination control logic corresponding to each connected device is determined. The device control strategy correspondence includes the coordination control logic corresponding to different device types under different voltage levels.

[0152] In some embodiments, the connection device includes: a photovoltaic device, an energy storage device, and an adjustable load device.

[0153] In some embodiments, the bus voltage grading thresholds include: four different voltage grading thresholds set based on the DC bus voltage rating, wherein two voltage grading thresholds are greater than the DC bus voltage rating, and the other two voltage grading thresholds are less than the DC bus voltage rating.

[0154] In some embodiments, determining the coordination control logic corresponding to each connected device based on the type of the connected device and a preset device control strategy correspondence includes:

[0155] When the DC bus voltage is greater than or equal to the first voltage level threshold, the photovoltaic equipment reduces power according to the droop control mode in the preset MPP-droop control logic, the energy storage equipment charges according to the maximum current threshold, and the adjustable load equipment operates in full load mode, wherein the values ​​of the first voltage level threshold to the fourth voltage level threshold decrease sequentially.

[0156] When the DC bus voltage is between the first voltage grading threshold and the second voltage grading threshold, the photovoltaic equipment reduces power according to the droop control mode in the MPP-droop control logic, the energy storage equipment is charged according to the preset hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0157] When the DC bus voltage is between the second voltage level threshold and the third voltage level threshold, the photovoltaic equipment operates according to the MPPT control mode in the preset MPP-droop control logic, the energy storage equipment switches to standby mode, and the adjustable load equipment operates in full load mode.

[0158] When the DC bus voltage is between the third voltage level threshold and the fourth voltage level threshold, the photovoltaic equipment operates at the maximum power point, the energy storage equipment discharges according to the hierarchical droop control logic, and the adjustable load equipment operates in full load mode.

[0159] When the DC bus voltage is less than or equal to the fourth voltage grading threshold, the photovoltaic equipment operates in the MPPT control mode of the MPP-droop control logic, the energy storage equipment discharges according to the maximum current threshold, and the adjustable load equipment is disconnected in layers.

[0160] In some embodiments, the MPP-droop control logic specifically includes:

[0161]

[0162] In the formula, The reference value representing the output power and voltage derivative of a photovoltaic unit. This is the upper limit of the reference value; Indicates the droop coefficient. The DC bus voltage is... This is the rated value of the DC bus voltage.

[0163] In some embodiments, the layered droop control logic specifically includes:

[0164]

[0165] In the formula, kbdp k bdi The PI parameters are for the tiered droop control of the energy storage unit. The DC bus voltage is... The rated value of the DC bus voltage. This is a reference value for the current of the energy storage device when it is operating within its normal range. The threshold values ​​are sequentially from the first voltage level threshold to the fourth voltage level threshold. This is the sag coefficient of the energy storage device. This is the maximum discharge current of the energy storage device. Let be the maximum charging current of the energy storage device, and s be the complex variable parameter of the transfer function.

[0166] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the terminals, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0167] In the several embodiments provided in this application, it should be understood that the disclosed terminals, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0168] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0169] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0170] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0171] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0172] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0173] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A coordinated control method for a multi-port solid-state transformer, characterized in that, include: Based on the topology information of the multi-port solid-state transformer, determine the connection device corresponding to each port in the multi-port solid-state transformer; The DC bus voltage of the multi-port solid-state transformer is collected, and the bus voltage level is determined based on the DC bus voltage and a preset bus voltage classification threshold. Based on the type of the connected device and in conjunction with the preset device control strategy correspondence, the coordination control logic corresponding to each connected device is determined. The device control strategy correspondence includes the coordination control logic corresponding to different device types under different voltage levels.

2. The multi-port solid-state transformer coordinated control method according to claim 1, characterized in that, The connection devices include: photovoltaic equipment, energy storage equipment, and adjustable load equipment.

3. The multi-port solid-state transformer coordinated control method according to claim 2, characterized in that, The bus voltage grading thresholds include four different voltage grading thresholds set based on the rated DC bus voltage, wherein two of the voltage grading thresholds are greater than the rated DC bus voltage, and the other two voltage grading thresholds are less than the rated DC bus voltage.

4. The multi-port solid-state transformer coordinated control method according to claim 2, characterized in that, Based on the type of the connected device and in conjunction with the preset device control strategy correspondence, the coordination control logic corresponding to each connected device is determined as follows: When the DC bus voltage is greater than or equal to the first voltage level threshold, the photovoltaic equipment reduces power according to the droop control mode in the preset MPP-droop control logic, the energy storage equipment charges according to the maximum current threshold, and the adjustable load equipment operates in full load mode, wherein the values ​​of the first voltage level threshold to the fourth voltage level threshold decrease sequentially. When the DC bus voltage is between the first voltage grading threshold and the second voltage grading threshold, the photovoltaic equipment reduces power according to the droop control mode in the MPP-droop control logic, the energy storage equipment is charged according to the preset hierarchical droop control logic, and the adjustable load equipment operates in full load mode. When the DC bus voltage is between the second voltage level threshold and the third voltage level threshold, the photovoltaic equipment operates according to the MPPT control mode in the preset MPP-droop control logic, the energy storage equipment switches to standby mode, and the adjustable load equipment operates in full load mode. When the DC bus voltage is between the third voltage level threshold and the fourth voltage level threshold, the photovoltaic equipment operates at the maximum power point, the energy storage equipment discharges according to the hierarchical droop control logic, and the adjustable load equipment operates in full load mode. When the DC bus voltage is less than or equal to the fourth voltage grading threshold, the photovoltaic equipment operates in the MPPT control mode of the MPP-droop control logic, the energy storage equipment discharges according to the maximum current threshold, and the adjustable load equipment is disconnected in layers.

5. The multi-port solid-state transformer coordinated control method according to claim 4, characterized in that, The MPP-droop control logic is specifically as follows: In the formula, The reference value representing the output power and voltage derivative of a photovoltaic unit. This is the upper limit of the reference value; Indicates the droop coefficient. The DC bus voltage is... This is the rated value of the DC bus voltage.

6. The multi-port solid-state transformer coordinated control method according to claim 4, characterized in that, The layered droop control logic is specifically as follows: In the formula, k bdp k bdi The PI parameters are for the tiered droop control of the energy storage unit. The DC bus voltage is... The rated value of the DC bus voltage. This is a reference value for the current of the energy storage device when it is operating within its normal range. The threshold values ​​are sequentially from the first voltage level threshold to the fourth voltage level threshold. This is the sag coefficient of the energy storage device. This is the maximum discharge current of the energy storage device. Let be the maximum charging current of the energy storage device, and s be the complex variable parameter of the transfer function.

7. A multi-port solid-state transformer coordinated control device, characterized in that, include: The port device determination unit is used to determine the connection device corresponding to each port in the multi-port solid-state transformer based on the topology information of the multi-port solid-state transformer. The bus voltage determination unit is used to collect the DC bus voltage of the multi-port solid-state transformer and determine the bus voltage level based on the DC bus voltage and a preset bus voltage classification threshold. A multi-port control logic matching unit is used to determine the coordination control logic corresponding to each connected device based on the type of the connected device and in conjunction with a preset device control strategy correspondence. The device control strategy correspondence includes the coordination control logic corresponding to different device types under different voltage levels.

8. A multi-port solid-state transformer coordinated control device according to claim 7, characterized in that, The connection equipment includes: photovoltaic equipment, energy storage equipment, and adjustable load equipment; The bus voltage grading thresholds include four different voltage grading thresholds set based on the rated DC bus voltage, wherein two of the voltage grading thresholds are greater than the rated DC bus voltage, and the other two voltage grading thresholds are less than the rated DC bus voltage.

9. A multi-port solid-state transformer coordination control terminal, characterized in that, include: Memory and processor; The memory is used to store program code, which corresponds to the multi-port solid-state transformer coordinated control method as described in any one of claims 1 to 6; The processor is used to read and execute the program code to implement the multi-port solid-state transformer coordinated control method corresponding to the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains program code that is read and executed by a processor to implement the multi-port solid-state transformer coordinated control method as described in any one of claims 1 to 6.

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