An energy management method and system of a DBS-based communication-free optical storage system

Abstract

This invention provides an energy management method and system for a communication-free photovoltaic-storage system based on DBS, relating to the field of photovoltaic energy storage technology. The method includes: setting several common DC bus threshold voltages; switching the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter based on the several common DC bus threshold voltages and the common DC bus voltage; and switching the operating mode of the DC / AC converter according to off-grid or grid-connected conditions. This invention establishes a unified multi-level common DC bus threshold voltage framework, driving the photovoltaic-side DC / DC converter to autonomously switch between maximum power point tracking (MPPT) mode and constant voltage mode based on real-time changes in the common DC bus voltage, and driving the battery-side bidirectional DC / DC converter to dynamically adjust its charging and discharging state. Simultaneously, it drives the DC / AC converter to switch between a three-loop off-grid control structure and a two-loop grid-connected control structure based on operating conditions. This achieves systematic coordinated management of the three converters under both grid-connected and off-grid conditions, solving the problem of difficulty in coordinating converter operating states during condition switching caused by the lack of a unified threshold framework in existing DBS methods, and improving the energy management reliability and operational stability of the photovoltaic-storage system under dual operating conditions.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic energy storage technology, and in particular to a communication-free photovoltaic energy storage management system and method based on DBS. Background Technology

[0002] Photovoltaic energy storage systems are an important form of distributed renewable energy local consumption and flexible power supply. A typical system consists of a photovoltaic array, energy storage batteries, a photovoltaic-side DC / DC converter, a battery-side bidirectional DC / DC converter, and a DC / AC converter. Each unit collects and distributes energy through a common DC bus. The coordinated operation of these converters requires sensing the global power state to determine their respective operating modes and output levels. To avoid the cost and reliability issues associated with communication links, a communication-free coordination control method based on DC bus signaling (DBS) has been proposed. This method utilizes the natural offset of the DC bus voltage caused by input-output power imbalance to reflect the system power state. Each converter achieves autonomous response by locally detecting the bus voltage, completing coordinated control without inter-unit communication links.

[0003] Existing research on DBS-based coordinated control of photovoltaics and energy storage has proposed several control strategies for single operating conditions, including grid-connected and off-grid scenarios. In grid-connected operation, the inverter typically maintains a stable bus voltage, with the photovoltaic side prioritizing maximum power point tracking (MPPT) and the battery side regulating charging and discharging based on power margins. In off-grid operation, the inverter handles output voltage regulation, and the photovoltaic and battery systems work together to maintain power balance. These single-condition strategies can achieve good control performance in specific scenarios.

[0004] However, existing DBS-based photovoltaic energy storage management methods still have shortcomings when dealing with the coordination of grid-connected and off-grid dual operating conditions and balancing multiple constraints. On the one hand, most existing methods are designed independently for a single operating condition, lacking a unified threshold setting framework and converter coordination rules for both grid-connected and off-grid operating conditions. This makes it difficult to ensure a smooth transition of the three converters' operating states during operating condition switching. Therefore, there is an urgent need for a photovoltaic energy storage management method that can systematically coordinate and manage the three converters based on a unified multi-level threshold under both grid-connected and off-grid dual operating conditions. Summary of the Invention

[0005] To overcome the shortcomings of existing DBS photovoltaic energy management methods in terms of lack of a systematic management framework for dual-condition collaborative control and multi-constraint coordination, this invention provides an energy management method and system for a communication-free photovoltaic energy storage system based on DBS.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: This invention provides an energy management method for a communication-free optical energy storage system based on DBS, comprising: Set several common DC bus threshold voltages; Based on the aforementioned threshold voltages of several common DC buses and Switch the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter; Switch the operating mode of the DC / AC converter according to whether it is an off-grid or grid-connected operating condition.

[0007] Preferably, the plurality of common DC bus threshold voltages include a first common DC bus threshold voltage, a second common DC bus threshold voltage, and a third common DC bus threshold voltage; With the preset nominal voltage Based on the preset bus voltage step size, As a step, the threshold voltage of the first common DC bus is The threshold voltage of the second common DC bus is The threshold voltage of the third common DC bus is .

[0008] Preferably, based on the threshold voltages of the plurality of common DC buses and Switching the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter includes: The photovoltaic-side DC / DC converter is based on and Adaptively switches between maximum power point tracking mode and constant voltage mode; The battery-side bidirectional DC / DC converter is based on , and Adjust the battery charging and discharging status.

[0009] Preferably, the operating mode of the DC / AC converter is switched according to off-grid or grid-connected operating conditions, including: The DC / AC converter uses a three-closed-loop control structure to supply power to the AC load under off-grid conditions; The DC / AC converter employs a dual closed-loop control structure with an outer loop for bus voltage and an inner loop for grid current under grid-connected operating conditions, in order to... Maintain at To control the target, the direction of grid-connected power flow is adjusted.

[0010] Preferably, the photovoltaic-side DC / DC converter is based on and Adaptive switching between maximum power point tracking mode and constant voltage mode, including: when < At that time, the photovoltaic-side DC / DC converter operates in maximum power point tracking mode; when ≥ At that time, the photovoltaic-side DC / DC converter operates in constant voltage mode.

[0011] Preferably, the battery-side bidirectional DC / DC converter is based on , and Adjusting the battery charge / discharge state includes: Calculate battery current reference value :

[0012] in, The preset battery current setting value, For based on and The bus overvoltage regulation amount obtained by PI regulation of the deviation, the The range of values ​​for is [-2× ,0], Based on and The undervoltage regulation amount of the bus obtained by PI regulation of the deviation, the The range of values ​​for is [0, 2×]. ], This refers to the maximum charge / discharge current amplitude of the battery. Adjust the battery charging and discharging state according to the battery current reference value: when < hour, Continue to increase As the battery continues to decrease, it transitions from charging to discharging. when ≤ ≤ hour, and All were limited to 0. Keep as Battery The corresponding power is used for continuous charging or discharging; when > hour, Continuously decreasing As the battery continues to grow, it transitions from discharging to charging.

[0013] Preferably, the DC / AC converter employs a three-closed-loop control structure to supply power to the AC load under off-grid conditions, including: The three-closed-loop control structure is composed of an output voltage RMS value loop, an output voltage loop, and an inductor current loop connected in series. The output voltage RMS loop outputs a voltage reference value based on a preset load rated voltage RMS value. The output voltage loop outputs the current reference value of the inductor current loop based on the voltage reference value; The inductor current loop outputs the duty cycle of the DC / AC converter after PI adjustment based on the current reference value of the inductor current loop, thereby driving the DC / AC converter to supply power to the AC load.

[0014] Preferably, the DC / AC converter employs a dual closed-loop control structure with an outer loop for bus voltage and an inner loop for grid-connected current under grid-connected operating conditions, in order to... Maintain at To control the target, the direction of grid-connected power flow is adjusted, including: The outer loop of the bus voltage is based on ,Will and The deviation is adjusted by a PI controller to output the grid-connected current; The inner loop of the grid-connected current performs closed-loop tracking control on the grid-connected current. After PI adjustment, it outputs the duty cycle of the DC / AC converter to drive the DC / AC converter to adjust the direction of grid-connected power flow.

[0015] Preferably, the battery current reference value Battery charging limit and battery discharge limit Apply safety constraints and limit the amplitude; The based on and The deviation is obtained through PI adjustment, the The range of values ​​for is [0, ...]. ]; The based on and The deviation is obtained through PI adjustment, the The range of values ​​is [- ,0]; Position the battery current clamp at and Between these points, a reference value for the battery current, limited by safety constraints, is obtained. ; in, This is a sampled value of the battery voltage. This is the open-circuit voltage corresponding to a fully charged battery. This is the open-circuit voltage corresponding to the lower discharge limit of the battery.

[0016] This invention also provides an energy management system based on a DBS-based non-communication photovoltaic energy storage system, comprising: The threshold setting module is used to set several common DC bus threshold voltages; The DC / DC converter operating mode switching module is used to switch operating modes based on the threshold voltages of the several common DC buses and Switch the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter; The DC / AC converter operating mode switching module is used to switch the operating mode of the DC / AC converter according to off-grid or grid-connected operating conditions.

[0017] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention provides an energy management method for a communication-free optical energy storage system based on DBS, comprising: setting several common DC bus threshold voltages; and based on the several common DC bus threshold voltages and... The operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter are switched; the operating mode of the DC / AC converter is switched according to off-grid or grid-connected conditions. This invention establishes a unified multi-level common DC bus threshold voltage framework, by... The real-time changes drive the photovoltaic-side DC / DC converter to autonomously switch between maximum power point tracking mode and constant voltage mode, and drive the battery-side bidirectional DC / DC converter to dynamically adjust the charging and discharging state. At the same time, based on the operating conditions, the DC / AC converter switches between a three-closed-loop off-grid control structure and a dual-closed-loop grid-connected control structure. This realizes the systematic coordinated management of the three converters under both grid-connected and off-grid operating conditions, and solves the problem that the existing DBS method is difficult to coordinate the operating state of the converter when switching operating conditions due to the lack of a unified threshold framework. This improves the energy management reliability and operational stability of the photovoltaic-storage system under dual operating conditions. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating an energy management method for a communication-free optical energy storage system based on DBS in Example 1. Figure 2 This is a schematic diagram of a communication-free optical storage system based on DBS in Example 2; Figure 3 This is a control block diagram of the battery-side bidirectional DC / DC converter in Example 2; Figure 4 This is a control block diagram of the photovoltaic-side DC / DC converter in Example 2; Figure 5 This is the off-grid control block diagram of the DC / AC converter in Example 2; Figure 6 This is a block diagram of the grid-connected control of the DC / AC converter in Example 2; Figure 7 This is an energy flow diagram of the photovoltaic energy storage system in Example 2 under off-grid conditions and battery charging status; Figure 8 This is an energy flow diagram of the photovoltaic energy storage system in Example 2 under off-grid conditions and battery discharge. Figure 9 This is an energy flow diagram of the photovoltaic energy storage system in Example 2, when the system is connected to the grid and transmitting power to the grid. Figure 10 This is an energy flow diagram for the photovoltaic energy storage system in Example 2, under grid-connected operation and with battery discharge and grid replenishment. Figure 11 This is an energy flow diagram for the photovoltaic energy storage system in Example 2, under grid-connected operation and with battery charging and grid supplementation. Figure 12 This is an energy flow diagram for the photovoltaic energy storage system in Example 2, under grid-connected operation and with battery charging and grid power transmission. Figure 13 This is a schematic diagram of the structure of an energy management system for a communication-free optical energy storage system based on DBS in Example 3.

[0019] Explanation of reference numerals in the attached figures 10: Photovoltaic modules; 20: Battery; 30: Common DC bus; 40: Photovoltaic-side DC / DC converter; 50: Battery-side bidirectional DC / DC converter; 60: DC / AC converter; 70: Power grid; 80: Load. Detailed Implementation

[0020] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Example 1 This embodiment provides an energy management method for a communication-free optical energy storage system based on DBS, such as... Figure 1 As shown, it includes: Set several common DC bus threshold voltages; Based on the threshold voltage of the several common DC bus and the bus voltage of the common DC bus, the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter are switched. Switch the operating mode of the DC / AC converter according to whether it is an off-grid or grid-connected operating condition.

[0023] In its specific implementation, this invention first sets several common DC bus threshold voltages; then, based on these common DC bus threshold voltages and the bus voltage of the common DC bus, it switches the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter; subsequently, it switches the operating mode of the DC / AC converter according to off-grid or grid-connected operating conditions. This invention establishes a unified multi-level common DC bus threshold voltage framework, by... The real-time changes drive the photovoltaic-side DC / DC converter to autonomously switch between maximum power point tracking mode and constant voltage mode, and drive the battery-side bidirectional DC / DC converter to dynamically adjust the charging and discharging state. At the same time, based on the operating conditions, the DC / AC converter switches between a three-closed-loop off-grid control structure and a dual-closed-loop grid-connected control structure. This realizes the systematic coordinated management of the three converters under both grid-connected and off-grid operating conditions, and solves the problem that the existing DBS method is difficult to coordinate the operating state of the converter when switching operating conditions due to the lack of a unified threshold framework. This improves the energy management reliability and operational stability of the photovoltaic-storage system under dual operating conditions.

[0024] Example 2 This embodiment provides an energy management method for a communication-free optical energy storage system based on DBS, including: The DBS-based communication-free optical storage system, such as Figure 2 As shown; Set several common DC bus threshold voltages; Based on the aforementioned threshold voltages of several common DC buses and Switch the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter; Switch the operating mode of the DC / AC converter according to whether it is an off-grid or grid-connected operating condition.

[0025] It should be noted that, in this embodiment, the plurality of common DC bus threshold voltages include a first common DC bus threshold voltage, a second common DC bus threshold voltage, and a third common DC bus threshold voltage. With the preset nominal voltage Based on the preset bus voltage step size, As a step, the threshold voltage of the first common DC bus is , the second common DC bus threshold voltage is , the third common DC bus threshold voltage is .

[0026] It should be noted that in this embodiment, is 800V, is 15V.

[0027] It should be noted that in this embodiment, based on the plurality of common DC bus threshold voltages and , the operation modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter are switched, and the control block diagram of the battery-side bidirectional DC / DC converter is shown in Figure 3 , which comprises: the photovoltaic-side DC / DC converter and , adaptively switches between a maximum power point tracking mode and a constant voltage mode; the battery-side bidirectional DC / DC converter according to , and , adjusts the charging and discharging states of the battery.

[0028] It should be noted that in this embodiment, the operation mode of the DC / AC converter is switched according to an off-grid working condition or a grid-connected working condition, comprising: the DC / AC converter adopts a three-closed-loop control structure to supply power to an AC load under the off-grid working condition; the DC / AC converter adopts a double-closed-loop control structure of a bus voltage outer loop and a grid-connected current inner loop under the grid-connected working condition, so as to maintain as a control target to adjust the flow direction of grid-connected power.

[0029] It should be noted that in this embodiment, the photovoltaic-side DC / DC converter adaptively switches between the maximum power point tracking mode and the constant voltage mode according to and , and a control block diagram of the photovoltaic-side DC / DC converter is shown in Figure 4 , comprising: when < , the photovoltaic-side DC / DC converter operates in the maximum power point tracking mode; when ≥ , the photovoltaic-side DC / DC converter operates in the constant voltage mode.

[0030] It should be noted that in this embodiment, with as the mode switching threshold of the photovoltaic side, when When the voltage rises to 830V, the photovoltaic side automatically exits MPPT mode and enters constant voltage mode to limit the photovoltaic injection power and prevent the DC bus voltage from continuing to rise; when When the voltage drops below 830V, the photovoltaic side resumes MPPT mode, making full use of the photovoltaic power generation capacity and realizing adaptive adjustment of photovoltaic output. It can maintain the bus voltage within a safe range under both power surplus and power shortage conditions.

[0031] It should be noted that, in this embodiment, the battery-side bidirectional DC / DC converter is based on... , and Adjusting the battery charge / discharge state includes: Calculate battery current reference value :

[0032] in, The preset battery current setting value, Based on and The bus overvoltage regulation amount obtained by PI regulation of the deviation, the The range of values ​​for is [-2× ,0], Based on and The undervoltage regulation amount of the bus obtained by PI regulation of the deviation, the The range of values ​​for is [0, 2×]. ], This refers to the maximum charge / discharge current amplitude of the battery. Adjust the battery charging and discharging state according to the battery current reference value: when < hour, Continue to increase As the battery continues to decrease, it transitions from charging to discharging. when ≤ ≤ hour, and All were limited to 0. Keep as Battery The corresponding power is used for continuous charging or discharging; when > hour, Continuously decreasing As the battery continues to grow, it transitions from discharging to charging.

[0033] It should be noted that, in this embodiment, and All use PI regulation, battery current reference value Capable of continuous and smooth response This deviation avoids abrupt switching between charging and discharging modes, reduces the impact of large currents on the battery, and helps extend the cycle life of the energy storage battery while maintaining system power balance.

[0034] It should be noted that, in this embodiment, the preset battery current setting value... There are three initial operating modes.

[0035] The first type is the load priority mode. =- The battery initially operates in a discharging state, prioritizing continuous power supply to the load, and can operate in both off-grid and grid-connected conditions. The second type is the grid-priority grid connection mode. ∈(- ,0), the battery initially operates in a discharge state, transmitting the excess power of the photovoltaic and battery to the grid, and only operates in grid-connected conditions; The third type is the battery priority mode. = The battery initially operates in a charging state, prioritizing battery charging, and can operate in both off-grid and grid-connected conditions. The above three modes are only used to determine the initial operating tendency of the system. During operation, the system will dynamically adjust Ibatref through IBus1 and IBus2 according to the real-time changes of VBus, and will not maintain the initial state.

[0036] It should be noted that in this embodiment, the DC / AC converter uses a three-closed-loop control structure to supply power to the AC load under off-grid conditions. The off-grid control block diagram of the DC / AC converter is shown below. Figure 5 As shown, it includes: The three-closed-loop control structure is composed of an output voltage RMS value loop, an output voltage loop, and an inductor current loop connected in series. The output voltage RMS loop outputs a voltage reference value based on a preset load rated voltage RMS value. The output voltage loop outputs the current reference value of the inductor current loop based on the voltage reference value; The inductor current loop outputs the duty cycle of the DC / AC converter after PI adjustment based on the current reference value of the inductor current loop, thereby driving the DC / AC converter to supply power to the AC load.

[0037] It should be noted that, in this embodiment, the output voltage loop preferably incorporates a repetitive controller. The repetitive controller, by accumulating and compensating for periodic voltage errors, can effectively suppress output voltage harmonics caused by nonlinear loads, reduce total harmonic distortion of the output voltage, and improve off-grid power supply quality. In the three-loop cascade structure, the output voltage RMS loop has a slower response speed but can accurately track the voltage amplitude; the response speeds of the output voltage loop and the inductor current loop increase sequentially. The synergistic effect of the three loops enables the DC / AC converter to maintain output voltage stability even under sudden load changes.

[0038] It should be noted that, in this embodiment, the DC / AC converter adopts a dual closed-loop control structure with an outer loop for bus voltage and an inner loop for grid-connected current under grid-connected operating conditions, in order to... Maintain at To control the grid-connected power flow direction, the grid-connected control block diagram of the DC / AC converter is as follows: Figure 6 The following are included: The outer loop of the bus voltage is based on ,Will and The deviation is adjusted by a PI controller to output the grid-connected current; The inner loop of the grid-connected current performs closed-loop tracking control on the grid-connected current. After PI adjustment, it outputs the duty cycle of the DC / AC converter to drive the DC / AC converter to adjust the direction of grid-connected power flow.

[0039] It should be noted that, in this embodiment, a repetitive controller is preferably introduced into the inner loop of the grid-connected current. The repetitive controller, by compensating for the periodic tracking error of the grid-connected current, can effectively suppress grid-connected current harmonics, improve the waveform quality of the grid-connected current, reduce total harmonic distortion of the grid-connected current, and meet the grid-connected power quality requirements. The outer loop of the bus voltage is stable. At It provides a stable operating reference for the threshold control logic of the photovoltaic and battery-side DC / DC converters, and realizes power coordination between the DC / AC converter and the two DC / DC converters.

[0040] It should be noted that, in this embodiment, the battery current reference value... Battery charging limit and battery discharge limit Apply safety constraints and limit the amplitude; The based on and The deviation is obtained through PI adjustment, the The range of values ​​for is [0, ...]. ]; The based on and The deviation is obtained through PI adjustment, the The range of values ​​is [- ,0]; Position the battery current clamp at and Between these points, a reference value for the battery current, limited by safety constraints, is obtained. ; in, This is a sampled value of the battery voltage. This is the open-circuit voltage corresponding to a fully charged battery. This is the open-circuit voltage corresponding to the lower discharge limit of the battery.

[0041] It should be noted that the energy flow direction of the photovoltaic energy storage system under off-grid conditions and when the battery is charging is as follows: Figure 7 As shown, the energy flow direction of the photovoltaic energy storage system under off-grid conditions and battery discharge is as follows: Figure 8 As shown; The energy flow direction when the photovoltaic energy storage system is connected to the grid and transmitting power to the grid is as follows: Figure 9 As shown, the energy flow of the photovoltaic energy storage system under grid-connected conditions and with both battery discharge and grid replenishment is as follows: Figure 10 As shown, the energy flow direction of the photovoltaic energy storage system under grid-connected operation and with battery charging and grid supplementation is as follows: Figure 11 As shown, the energy flow direction of the photovoltaic energy storage system under grid-connected operation and with battery charging and grid transmission is as follows: Figure 12 As shown; It should be noted that, in this embodiment, This is the open-circuit voltage of the energy storage battery when its state of charge is close to 100%. This is the open-circuit voltage of the energy storage battery when its state of charge is close to 20%. Within the normal operating range... In and between, near , near- Safety constraint limit does not intervene The calculation; when near hour, Automatically decreases and approaches 0. The battery is limited downwards to prevent further charging and overcharging. near hour, Automatically increases and approaches 0. The discharge limit is set to prevent the battery from continuing to discharge, thus preventing over-discharge and extending the lifespan of the energy storage battery.

[0042] The first type is a power deficiency state, corresponding to Below 785V. In this state, the battery-side bidirectional DC / DC converter... Continue to increase As the power output of the battery continues to decrease, its discharge capacity to the common DC bus increases; the photovoltaic-side DC / DC converter operates in maximum power point tracking mode to fully utilize the photovoltaic power generation capacity; the DC / AC converter continuously supplies power to the load or delivers power to the grid. The synergistic effect of these three factors enables… It rebounded and stabilized around 785V.

[0043] The second type is the power balance state, corresponding to 785V≤ ≤815V. Under this condition, and All were limited to 0, batteries were charged. The corresponding power is charged or discharged smoothly; the photovoltaic-side DC / DC converter continues to operate in maximum power point tracking mode; the DC / AC converter maintains normal operation, and the overall system power is in balance.

[0044] The third type is the state of excess power, corresponding to Above 815V. In this state, Continuously decreasing Increase, and the battery charging output increases; when When the voltage is further increased to 830V, the photovoltaic-side DC / DC converter switches from maximum power point tracking mode to constant voltage mode to actively limit the photovoltaic injected power and prevent the bus voltage from continuing to rise.

[0045] All three control states mentioned above are controlled by The real-time changes are automatically triggered, and each converter can autonomously switch to the corresponding mode to maintain the dynamic balance of system power without the need for a communication link.

[0046] Example 3 This embodiment provides an energy management system for a communication-free optical energy storage system based on DBS, used to implement the energy management method for a communication-free optical energy storage system based on DBS described in Embodiment 1 or 2, such as... Figure 13 As shown, it includes: The threshold setting module is used to set several common DC bus threshold voltages; The DC / DC converter operating mode switching module is used to switch operating modes based on the threshold voltages of the several common DC buses and Switch the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter; The DC / AC converter operating mode switching module is used to switch the operating mode of the DC / AC converter according to off-grid or grid-connected operating conditions.

[0047] The same or similar labels correspond to the same or similar parts; The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An energy management method for a communication-free optical energy storage system based on DBS, characterized in that, The communication-free photovoltaic-storage system includes a photovoltaic-side DC / DC converter, a battery-side bidirectional DC / DC converter, a DC / AC converter, and a common DC bus. The photovoltaic-side DC / DC converter, the battery-side bidirectional DC / DC converter, and the DC / AC converter are respectively connected to the common DC bus, and the bus voltage of the common DC bus is... ; Set several common DC bus threshold voltages; Based on the aforementioned threshold voltages of several common DC buses and Switch the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter; Switch the operating mode of the DC / AC converter according to whether it is an off-grid or grid-connected operating condition.

2. The energy management method for a communication-free optical energy storage system based on DBS according to claim 1, characterized in that, The plurality of common DC bus threshold voltages include a first common DC bus threshold voltage, a second common DC bus threshold voltage, and a third common DC bus threshold voltage; With the preset nominal voltage Based on the preset bus voltage step size, As a step, the threshold voltage of the first common DC bus is The threshold voltage of the second common DC bus is The threshold voltage of the third common DC bus is .

3. The energy management method for a communication-free optical energy storage system based on DBS according to claim 2, characterized in that, Based on the aforementioned threshold voltages of several common DC buses and Switching the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter includes: The photovoltaic-side DC / DC converter is based on and Adaptively switches between maximum power point tracking mode and constant voltage mode; The battery-side bidirectional DC / DC converter is based on , and Adjust the battery charging and discharging status.

4. The energy management method for a communication-free optical energy storage system based on DBS according to claim 1, characterized in that, Depending on whether the operation is off-grid or grid-connected, the operating mode of the DC / AC converter is switched, including: The DC / AC converter uses a three-closed-loop control structure to supply power to the AC load under off-grid conditions; The DC / AC converter employs a dual closed-loop control structure with an outer loop for bus voltage and an inner loop for grid current under grid-connected operating conditions, in order to... Maintain at To control the target, the direction of grid-connected power flow is adjusted.

5. The energy management method for a communication-free optical energy storage system based on DBS according to claim 3, characterized in that, Photovoltaic-side DC / DC converter according to and Adaptive switching between maximum power point tracking mode and constant voltage mode, including: when < At that time, the photovoltaic-side DC / DC converter operates in maximum power point tracking mode; when ≥ At that time, the photovoltaic-side DC / DC converter operates in constant voltage mode.

6. The energy management method for a communication-free optical energy storage system based on DBS according to claim 3, characterized in that, The battery-side bidirectional DC / DC converter is based on , and Adjusting the battery charge / discharge state includes: Calculate battery current reference value : in, The preset battery current setting value, Based on and The bus overvoltage regulation amount obtained by PI regulation of the deviation, the The range of values ​​for is [-2× ,0], Based on and The undervoltage regulation amount of the bus obtained by PI regulation of the deviation, the The range of values ​​for is [0, 2×]. ], This refers to the maximum charge / discharge current amplitude of the battery. Adjust the battery charging and discharging state according to the battery current reference value: when < hour, Continue to increase As the battery continues to decrease, it transitions from charging to discharging. when ≤ ≤ hour, and All were limited to 0. Keep as Battery The corresponding power is used for continuous charging or discharging; when > hour, Continuously decreasing As the battery continues to grow, it transitions from discharging to charging.

7. The energy management method for a communication-free optical energy storage system based on DBS according to claim 4, characterized in that, The DC / AC converter employs a three-closed-loop control structure to supply power to the AC load under off-grid conditions, including: The three-closed-loop control structure is composed of an output voltage RMS value loop, an output voltage loop, and an inductor current loop connected in series. The output voltage RMS loop outputs a voltage reference value based on a preset load rated voltage RMS value. The output voltage loop outputs the current reference value of the inductor current loop based on the voltage reference value; The inductor current loop outputs the duty cycle of the DC / AC converter after PI adjustment based on the current reference value of the inductor current loop, thereby driving the DC / AC converter to supply power to the AC load.

8. The energy management method for a communication-free optical energy storage system based on DBS according to claim 4, characterized in that, The DC / AC converter employs a dual closed-loop control structure with an outer loop for bus voltage and an inner loop for grid-connected current under grid-connected conditions, in order to... Maintain at To control the target, the direction of grid-connected power flow is adjusted, including: The outer loop of the bus voltage is based on ,Will and The deviation is adjusted by a PI controller to output the grid-connected current; The inner loop of the grid-connected current performs closed-loop tracking control on the grid-connected current. After PI adjustment, it outputs the duty cycle of the DC / AC converter to drive the DC / AC converter to adjust the direction of grid-connected power flow.

9. The energy management method for a communication-free optical energy storage system based on DBS according to claim 6, characterized in that, The battery current reference value Battery charging limit and battery discharge limit Apply safety constraints and limit the amplitude; The based on and The deviation is obtained through PI adjustment, the The range of values ​​for is [0, ...]. ]; The based on and The deviation is obtained through PI adjustment, the The range of values ​​is [- ,0]; Position the battery current clamp at and Between these points, a reference value for the battery current, limited by safety constraints, is obtained. ; in, This is a sampled value of the battery voltage. This is the open-circuit voltage corresponding to a fully charged battery. This is the open-circuit voltage corresponding to the lower discharge limit of the battery.

10. An energy management system for a DBS-based non-communication optical energy storage system, used to implement the energy management method for a DBS-based non-communication optical energy storage system as described in any one of claims 1 to 9, characterized in that, include: The threshold setting module is used to set several common DC bus threshold voltages; The DC / DC converter operating mode switching module is used to switch operating modes based on the threshold voltages of the several common DC buses and Switch the operating modes of the photovoltaic-side DC / DC converter and the battery-side bidirectional DC / DC converter; The DC / AC converter operating mode switching module is used to switch the operating mode of the DC / AC converter according to off-grid or grid-connected operating conditions.

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