A three-phase light storage hybrid system power optimization distribution method and system

Abstract

The application relates to the technical field of electric power, and discloses a three-phase light storage hybrid system power optimization distribution method and system. The method comprises the following steps: collecting the total output power of each photovoltaic unit in each phase circuit of a three-phase circuit, the output power of an H-bridge module in each photovoltaic unit in each single-phase cascade link, the residual power of a battery module in each energy storage unit, the grid-connected current of each phase circuit, and the H-bridge module modulation ratio of each photovoltaic unit and each energy storage unit; calculating the phase-to-phase total power imbalance difference of the three-phase circuit and the output power imbalance difference of the H-bridge module in each photovoltaic unit in the single-phase cascade link; according to the imbalance difference amplitude, determining whether to enable parallel or series energy storage units and entering a corresponding mode interval; and checking the H-bridge module modulation ratio of each photovoltaic unit and each energy storage unit in real time, avoiding over-modulation conditions throughout the process, and outputting balanced modulation waves for grid connection. The application compensates for the photovoltaic power difference through energy storage charging and discharging, realizes three-phase and intra-phase power balance, and avoids over-modulation and power generation loss.

Description

Technical Field

[0001] This invention relates to the field of power technology, specifically to a method and system for optimizing power allocation in a three-phase photovoltaic-storage hybrid system. Background Technology

[0002] When cascaded H-bridge converters are used in grid-connected photovoltaic power generation, their series modular structure supports distributed maximum power point tracking and modular expansion, and can achieve excellent output waveform quality at lower switching frequencies. However, when the output power of the photovoltaic strings connected to the DC side of each H-bridge unit is unbalanced due to uneven illumination, module degradation, or partial shading, the difference in output voltage amplitude of each unit will be directly reflected in the grid-connected current waveform, affecting power quality. In severe cases, in order to maintain the waveform quality of the grid-connected current, the modulation ratio of the higher-power unit may exceed the linear adjustment range, causing overmodulation, resulting in grid-connected current distortion and threatening the stable operation of the system.

[0003] To address the aforementioned power imbalance problem, traditional solutions primarily employ zero-sequence voltage injection to achieve three-phase power balance and adjust the modulation waves of each H-bridge module to achieve intra-phase power balance. However, this method has a clear limitation on its adjustment range—when the power difference between photovoltaic strings exceeds this range, the system cannot maintain power balance solely through modulation wave adjustment. In this situation, to maintain grid-connected power quality, higher-power photovoltaic modules are forced to exit maximum power point tracking mode, actively reducing their output power to meet system balance requirements. This results in a direct loss of power generation, reducing the overall power generation efficiency and economic benefits of the photovoltaic system. Summary of the Invention

[0004] To address existing problems, this invention provides a power optimization allocation method and system for a three-phase photovoltaic-storage hybrid system. By adjusting the charging and discharging power of the energy storage system to actively compensate for the power difference between photovoltaic strings, it solves the problem that traditional zero-sequence voltage injection methods must sacrifice photovoltaic power generation when the power imbalance exceeds the adjustment range. This achieves power balance between the three phases and within each H-bridge unit, while avoiding overmodulation and ensuring grid-connected power quality. Through autonomous management of the state of charge of the energy storage system, it ensures that the energy storage units have sufficient power compensation capability when needed, improving the operational safety and stability of the system under different lighting conditions.

[0005] To achieve the above objectives, the present invention provides the following technical solution.

[0006] This invention provides a method for optimizing power allocation in a three-phase photovoltaic-storage hybrid system, comprising the following steps: S1. Real-time acquisition of the total output power P of each photovoltaic unit in each phase of the three-phase circuit. pviThe output power P of the H-bridge module in each photovoltaic unit within each cascaded link pvij The remaining state of charge (SOC) of the battery modules in each energy storage unit. ij The grid-connected current of each phase circuit and the modulation ratio of the H-bridge module of each photovoltaic unit and each energy storage unit; S2. Calculate the total power imbalance difference P between phases in a three-phase circuit. DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi ; S3. Based on the magnitude of the imbalance difference, determine whether to activate the parallel or series energy storage unit and enter the corresponding mode range: if it is determined that parallel energy storage compensation or parallel energy storage self-recovery is adopted, then execute the control logic of one of modes 1-8; if it is determined that series energy storage compensation or series energy storage self-recovery is adopted, then execute the control logic of one of modes 9-16. S4. Real-time verification of the modulation ratio of the H-bridge module of each photovoltaic unit and each energy storage unit, avoiding over-modulation conditions throughout the process, and outputting a balanced modulated wave for grid connection.

[0007] As a further improvement of the present invention, when the total power imbalance difference between phases of the three-phase circuit is P DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi When the threshold is exceeded, the output active power of each energy storage unit is adjusted when switching to parallel or series energy storage compensation mode to ensure that the total output power P of each phase of the three-phase circuit is equal to that of the parallel or series energy storage compensation mode. pvi The output power P of the H-bridge module in each photovoltaic unit within the equal, single-phase cascaded link pvij equal.

[0008] As a further improvement of the present invention, the parallel energy storage compensation mode is one of modes 1-5, wherein mode 1 is the output power imbalance difference P of the H-bridge module in each photovoltaic unit in the i-th phase cascaded link. DPi The value equals 0, at which point the parallel energy storage unit B is controlled. ij Exit system operation; Mode 2 refers to the output power imbalance difference P of the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi >0, and the remaining SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is ij The SOC of the energy storage unit is greater than the lower threshold. min At this time, control the parallel energy storage unit B ij Entering discharge mode, the discharge power is P DPi Mode 3 refers to the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is greater than 0. ijLess than or equal to the lower threshold SOC of the energy storage unit min At this time, each parallel energy storage unit in phase i is controlled to exit system operation; the mode 4 is the output power imbalance difference P of the H-bridge module in each photovoltaic unit in the cascaded link of phase i. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is less than 0. ij less than the upper limit threshold SOC of the energy storage unit max At this time, control the parallel energy storage unit B ij Entering charging mode, charging power is P DPi Mode 5 refers to the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is less than 0. ij The SOC (State of Charge) of the energy storage unit is greater than or equal to the upper limit threshold. max At this point, each parallel energy storage unit in phase i is controlled to exit system operation.

[0009] As a further improvement of the present invention, one of the series energy storage compensation modes 9-13, wherein mode 9 is the inter-phase total power imbalance difference P of the three-phase circuit. DSi When the value equals 0, all series-connected energy storage units in phase i are shut down from system operation; mode 10 refers to the total power imbalance difference P between phases of the three-phase circuit. DSi The SOC of each energy storage unit in phase i is greater than 0 and is the average remaining energy value. Siavg less than the upper limit threshold SOC of the energy storage unit max At this time, all series-connected energy storage units in phase i are controlled to enter charging mode, and the total charging power is P. DSi Mode 11 refers to the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is greater than 0 and is the average remaining energy value. Siavg The SOC (State of Charge) of the energy storage unit is greater than or equal to the upper limit threshold. max At this time, all energy storage units in phase i are controlled to exit system operation; the mode 12 is the total power imbalance difference P between phases of the three-phase circuit. DSi The SOC of each energy storage unit in phase i is less than 0 and is the average remaining energy value. Siavg The SOC of the energy storage unit is greater than the lower threshold. min At this time, all series-connected energy storage units in phase i are controlled to enter discharge mode, and the total charging power is P. DSi Mode 13 refers to the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is less than 0 and is the average remaining energy value. Siavg Less than or equal to the lower threshold SOC of the energy storage unit minAt this point, all energy storage units in phase i are controlled to exit system operation.

[0010] As a further improvement of the present invention, when the total power imbalance difference between phases of the three-phase circuit is P DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi When all are within a controllable range and the remaining SOC of the battery modules in the energy storage unit is lower than the lower threshold, the system switches to the energy storage self-recovery mode, controlling the surplus power of each photovoltaic unit in each phase circuit to charge the energy storage units connected in parallel or series, and simultaneously performing SOC equalization adjustment of the energy storage units on the single-phase cascaded link.

[0011] As a further improvement of the present invention, the parallel energy storage self-recovery mode is one of modes 6-8, wherein mode 6 is the total remaining energy SOC of each energy storage unit in the i-th phase. i Equal to the total remaining power setting value (SOC) set At this point, all parallel energy storage units in phase i are controlled to exit system operation; mode 7 is the total remaining power SOC of all energy storage units in phase i. i Greater than the total remaining power setting (SOC) set At this time, control the parallel energy storage unit B ij Entering discharge mode; mode 8 is the total remaining charge (SOC) of each energy storage unit in phase i. i Less than or equal to the total remaining battery power setting (SOC) set At this time, control the parallel energy storage unit B ij Enter charging mode.

[0012] As a further improvement of the present invention, the series energy storage self-recovery mode is one of modes 14-16, wherein mode 14 is the average remaining charge (SOC) of each energy storage unit in the i-th phase. Siavg Equal to the total remaining power setting value (SOC) set At this point, all series-connected energy storage units in phase i are shut down from system operation; mode 15 is the average remaining charge (SOC) of each energy storage unit in phase i. Siavg Greater than the total remaining power setting (SOC) set At this time, all series-connected energy storage units in phase i are controlled to enter the discharge mode; the mode 16 is the average remaining charge (SOC) of each energy storage unit in phase i. Siavg Less than the total remaining battery power setting (SOC) set At this time, all series-connected energy storage units in phase i are controlled to enter charging mode.

[0013] This invention also discloses a power optimization allocation system for a three-phase photovoltaic-storage hybrid system, used to implement the power optimization allocation method for the aforementioned three-phase photovoltaic-storage hybrid system. The system includes three-phase lines, each phase line comprising a photovoltaic unit, a series energy storage unit connected in series with the photovoltaic unit, and a parallel energy storage unit connected in parallel with the photovoltaic unit. Each photovoltaic unit, series energy storage unit, and parallel energy storage unit includes an H-bridge module and a voltage regulator capacitor. The H-bridge module is connected in parallel with the voltage regulator capacitor. The H-bridge module includes at least four IGBT transistors, each IGBT transistor equipped with a freewheeling diode.

[0014] As a further improvement of the present invention, the series energy storage unit further includes a single battery cell connected in parallel with the voltage stabilizing capacitor or a battery pack composed of multiple batteries connected in series.

[0015] As a further improvement of the present invention, the parallel energy storage unit further includes a bidirectional DC-DC converter or a bidirectional energy storage branch connected in parallel with the voltage stabilizing capacitor.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This method collects the output power, energy storage SOC, and modulation ratio of each photovoltaic unit in real time, calculates the power imbalance difference between phases and within phases, and adaptively switches between parallel and series energy storage compensation modes according to the degree of imbalance. This solves the problems of power quality degradation and over-modulation of grid-connected current caused by power imbalance of photovoltaic strings in cascaded H-bridge photovoltaic systems, and realizes balanced power distribution between the three phases and within each H-bridge unit, maintaining maximum power point tracking mode as much as possible.

[0017] Preferably, the photovoltaic power gap is actively compensated by the charging and discharging of the energy storage unit, so that the total output power of each phase and the power of each H-bridge unit in the phase tend to be consistent, avoiding the power generation loss caused by the traditional zero-sequence voltage injection method being forced to exit the maximum power point tracking mode after exceeding the adjustment range.

[0018] Preferably, based on the direction of power imbalance (positive / negative) and the energy storage SOC state (whether it is below the lower limit or above the upper limit), the parallel energy storage units are controlled to be in three states: discharge compensation, charge recovery, or shutdown, respectively, to ensure that the energy storage battery is prevented from being overcharged or over-discharged while compensating for the power gap, thus taking into account both system power balance and energy storage safety.

[0019] Preferably, based on the direction of the interphase power imbalance and the average SOC of the energy storage in that phase, the series-connected energy storage units are controlled to be in a charging, discharging, or de-energized state, which achieves rapid compensation for the interphase power imbalance. At the same time, the average SOC is used to avoid the problem that individual energy storage units in a single phase cannot work properly due to excessively low SOC.

[0020] Preferably, when the power imbalance is within a controllable range and the energy storage SOC is below the lower limit, the system automatically switches to the energy storage self-recovery mode, uses the surplus photovoltaic power to charge the energy storage unit, and simultaneously performs SOC equalization adjustment of each energy storage unit in the same phase to ensure that the energy storage unit has sufficient discharge capacity before the next power compensation demand arrives.

[0021] Preferably, based on the deviation direction of the total SOC of energy storage from the set value, the parallel energy storage units are controlled to be in the discharge, charging or de-energized state respectively. When the energy storage SOC is too high, it actively discharges to make room for subsequent charging. When the SOC is too low, it uses the surplus power of photovoltaic to charge and restore, thus realizing active health management of energy storage power.

[0022] Preferably, based on the deviation direction of the average SOC of each phase energy storage unit from the set value, the series energy storage units are controlled to be in the discharging, charging, or de-energizing state respectively, which ensures the balance of the energy of each phase energy storage unit and avoids the risk that a phase cannot work normally when the subsequent power compensation demand arrives due to the low SOC of a certain phase energy storage unit.

[0023] Preferably, by combining photovoltaic units with series and parallel energy storage units in a topology, and using the circuit structure of H-bridge modules and voltage regulator capacitors, a hardware execution basis is provided for the above-mentioned power optimization allocation method, enabling rapid response and accurate execution of energy storage power compensation commands.

[0024] Preferably, the battery pack is connected in parallel with the H-bridge module through a voltage stabilizing capacitor, providing an independent energy storage compensation channel for each H-bridge unit, enabling each H-bridge unit within the phase to independently regulate energy storage charging and discharging according to its own photovoltaic power deviation.

[0025] Preferably, the bidirectional DC-DC converter or bidirectional energy storage branch realizes bidirectional power flow control between the energy storage unit and the DC bus, enabling the parallel energy storage unit to flexibly switch charging / discharging modes according to the direction of power imbalance between the three phases, and providing a power conversion channel for power balance between the three phases. Attached Figure Description

[0026] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and are not intended to specifically limit the shapes and proportions of the components. In the drawings: Figure 1 This is a flowchart illustrating a power optimization allocation method for a three-phase photovoltaic-storage hybrid system in Example 1. Figure 2 This is a detailed flowchart of a power optimization allocation method for a three-phase photovoltaic-storage hybrid system in Example 1; Figure 3This is a schematic diagram of the configuration of a power optimization allocation system for a three-phase photovoltaic-storage hybrid system in Example 1; Figure 4 This is a diagram of the photovoltaic unit circuit topology in Example 1; Figure 5 This is a circuit topology diagram of the series energy storage unit in Example 1; Figure 6 This is a circuit topology diagram of the parallel energy storage unit in Example 1; Figure 7 This is a topology diagram of the bidirectional energy storage branch of the parallel energy storage unit in Example 2. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0028] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] Example 1 like Figure 1 As shown, this embodiment provides a power optimization allocation method for a three-phase photovoltaic-storage hybrid system, including the following steps: S1. Real-time acquisition of the total output power P of each photovoltaic unit in each phase of the three-phase circuit. pvi The output power P of the H-bridge module in each photovoltaic unit within each cascaded link pvij The remaining state of charge (SOC) of the battery modules in each energy storage unit. ijThe grid-connected current of each phase circuit and the modulation ratio of the H-bridge module of each photovoltaic unit and each energy storage unit; S2. Calculate the total power imbalance difference P between phases in a three-phase circuit. DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi ; S3. Based on the magnitude of the imbalance difference, determine whether to activate the parallel or series energy storage unit and enter the corresponding mode range: if it is determined that parallel energy storage compensation or parallel energy storage self-recovery is adopted, then execute the control logic of one of modes 1-8; if it is determined that series energy storage compensation or series energy storage self-recovery is adopted, then execute the control logic of one of modes 9-16. S4. Real-time verification of the modulation ratio of the H-bridge module of each photovoltaic unit and each energy storage unit, avoiding over-modulation conditions throughout the process, and outputting a balanced modulated wave for grid connection.

[0031] like Figure 2 As shown, when the total power imbalance difference P between phases of a three-phase circuit... DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi When the threshold is exceeded, the output active power of each energy storage unit is adjusted when switching to parallel or series energy storage compensation mode to ensure that the total output power P of each phase of the three-phase circuit is equal to that of the parallel or series energy storage compensation mode. pvi The output power P of the H-bridge module in each photovoltaic unit within the equal, single-phase cascaded link pvij equal.

[0032] like Figure 2 As shown, when the total power imbalance difference P between phases of a three-phase circuit... DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi When all are within a controllable range and the remaining SOC of the battery modules in the energy storage unit is lower than the lower threshold, the system switches to the energy storage self-recovery mode, controlling the surplus power of each photovoltaic unit in each phase circuit to charge the energy storage units connected in parallel or series, and simultaneously performing SOC equalization adjustment of the energy storage units on the single-phase cascaded link.

[0033] like Figure 2 As shown, the parallel energy storage compensation mode is one of modes 1-5, where mode 1 is the output power imbalance difference P of the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The value equals 0, at which point the parallel energy storage unit B is controlled. ij Exit system operation.

[0034] Mode 2 is the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi >0, and the remaining SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is ijThe SOC of the energy storage unit is greater than the lower threshold. min At this time, control the parallel energy storage unit B ij Entering discharge mode, the discharge power is P DPi .

[0035] Mode 3 is the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is greater than 0. ij Less than or equal to the lower threshold SOC of the energy storage unit min At this point, each parallel energy storage unit in phase i is controlled to exit system operation.

[0036] Mode 4 represents the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is less than 0. ij less than the upper limit threshold SOC of the energy storage unit max At this time, control the parallel energy storage unit B ij Entering charging mode, charging power is P DPi .

[0037] Mode 5 represents the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is less than 0. ij The SOC (State of Charge) of the energy storage unit is greater than or equal to the upper limit threshold. max At this point, each parallel energy storage unit in phase i is controlled to exit system operation.

[0038] like Figure 2 As shown, one of the series energy storage compensation modes 9-13 is shown, where mode 9 represents the total power imbalance difference P between phases of the three-phase circuit. DSi When the value equals 0, all series-connected energy storage units in phase i are shut down from system operation.

[0039] Mode 10 represents the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is greater than 0 and is the average remaining energy value. Siavg less than the upper limit threshold SOC of the energy storage unit max At this time, all series-connected energy storage units in phase i are controlled to enter charging mode, and the total charging power is P. DSi .

[0040] Mode 11 represents the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is greater than 0 and is the average remaining energy value. SiavgThe SOC (State of Charge) of the energy storage unit is greater than or equal to the upper limit threshold. max At this point, all energy storage units in phase i are controlled to exit system operation.

[0041] Mode 12 represents the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is less than 0 and is the average remaining energy value. Siavg The SOC of the energy storage unit is greater than the lower threshold. min At this time, all series-connected energy storage units in phase i are controlled to enter discharge mode, and the total charging power is P. DSi .

[0042] Mode 13 represents the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is less than 0 and is the average remaining energy value. Siavg Less than or equal to the lower threshold SOC of the energy storage unit min At this point, all energy storage units in phase i are controlled to exit system operation.

[0043] like Figure 2 As shown, the parallel energy storage self-recovery mode is one of modes 6-8, where mode 6 is the total remaining energy SOC of all energy storage units in phase i. i Equal to the total remaining power setting value (SOC) set At this point, all parallel energy storage units in phase i are controlled to exit system operation.

[0044] Mode 7 represents the total remaining energy (SOC) of all energy storage units in phase i. i Greater than the total remaining battery power setting (SOC) set At this time, control the parallel energy storage unit B ij Enter discharge mode.

[0045] Mode 8 represents the total remaining energy (SOC) of all energy storage units in phase i. i Less than or equal to the total remaining battery power setting (SOC) set At this time, control the parallel energy storage unit B ij Enter charging mode.

[0046] like Figure 2 As shown, the self-recovery mode of series energy storage is one of modes 14-16, where mode 14 is the average remaining charge (SOC) of each energy storage unit in the i-th phase. Siavg Equal to the total remaining power setpoint SOC set At this point, all series-connected energy storage units in phase i are shut down from system operation.

[0047] Mode 15 represents the average remaining charge (SOC) of each energy storage unit in phase i. Siavg Greater than the total remaining battery power setting (SOC) setAt this time, all series-connected energy storage units in phase i are controlled to enter the discharge mode.

[0048] Mode 16 represents the average remaining charge (SOC) of each energy storage unit in phase i. Siavg Less than the total remaining battery power setting (SOC) set At this time, all series-connected energy storage units in phase i are controlled to enter charging mode.

[0049] This embodiment also discloses a power optimization allocation system for a three-phase photovoltaic-storage hybrid system, used to implement a power optimization allocation method for a three-phase photovoltaic-storage hybrid system. The system includes three-phase lines, each phase line including a photovoltaic unit, a series energy storage unit connected in series with the photovoltaic unit, and a parallel energy storage unit connected in parallel with the photovoltaic unit. Each photovoltaic unit, series energy storage unit, and parallel energy storage unit includes an H-bridge module and a voltage regulator capacitor. The H-bridge module is connected in parallel with the voltage regulator capacitor. The H-bridge module includes at least four IGBTs, each IGBT equipped with a freewheeling diode. Figure 3 As shown, taking the c-th phase line as an example, photovoltaic units c1-1, c2-1...cn-1 are connected in series on the c-th phase line, and corresponding photovoltaic units c1-2, c2-2...cn-2 are connected in parallel. Energy storage units c1, c2...ck are also connected in series on the c-th phase line to suppress the total power imbalance difference P between phases. DSi .

[0050] Figure 4 This is a diagram of a photovoltaic unit circuit topology in this embodiment. iPj As a bypass switch, a controllable relay or mechanical switching switch can be used. Its function is to bypass and disconnect the photovoltaic unit from the single-phase circuit, thereby achieving fault isolation of the H-bridge module. iPj1 S iPj2 S iPj3 S iPj4 Each inverter uses four IGBT power switches, forming a standard single-phase full-bridge (H-bridge) inverter topology; each power device is connected in parallel with a reverse freewheeling diode. iPj This is a DC-side voltage regulator capacitor for the H-bridge, used to stabilize and buffer the DC bus voltage, and suppress voltage ripple on the photovoltaic side. V PVij Photovoltaic output voltage; I PVij The arrow indicates the direction of current flow for the photovoltaic output. V iPj is the voltage at the bypass switch port on the left side of the H-bridge, and is the voltage across the bypass switch.

[0051] Figure 5 This is a circuit topology diagram of a series energy storage unit in this embodiment. K iBj As a bypass switch, a controllable relay or mechanical switching switch can be used. Its function is to bypass and disconnect the energy storage unit from the single-phase circuit, thereby achieving fault isolation of the H-bridge module.iBj1 S iBj2 S iBj3 S iBj4 Each inverter uses four IGBT power switches, forming a standard single-phase full-bridge (H-bridge) inverter topology; each power device is connected in parallel with a reverse freewheeling diode. iBj This is the DC-side voltage regulator capacitor for the H-bridge, used to regulate and buffer the DC bus voltage, and suppress voltage ripple on the energy storage side. V Bij I is the terminal voltage of the energy storage battery. Bij This represents the operating current of the energy storage battery; the arrow indicates the current reference direction. V iBj is the voltage at the bypass switch port on the left side of the H-bridge, and is the voltage across the bypass switch.

[0052] Figure 6 This is a circuit topology diagram of a parallel energy storage unit according to this embodiment. The parallel energy storage unit also includes a bidirectional DC-DC converter connected in parallel with the voltage regulator capacitor. iPj As a bypass switch, a controllable relay or mechanical switching switch can be used. Its function is to bypass and disconnect the energy storage unit from the single-phase circuit, thereby achieving fault isolation of the H-bridge module. iPj1 S iPj2 S iPj3 S iPj4 Each inverter uses four IGBT power switches, forming a standard single-phase full-bridge (H-bridge) inverter topology; each power device is connected in parallel with a reverse freewheeling diode. iPj This is the DC-side voltage regulator capacitor for the H-bridge, used to regulate and buffer the DC bus voltage, and suppress voltage ripple on the energy storage side. V PVij I is the DC bus voltage of the bidirectional DC-DC converter. PVij This represents the operating current on the DC bus side; the arrow indicates the current reference direction. V PVBij I is the battery-side voltage of the bidirectional DC-DC converter. PVBij This represents the battery-side operating current; the arrow indicates the current reference direction. V iPj is the voltage at the bypass switch port on the left side of the H-bridge, and is the voltage across the bypass switch.

[0053] Furthermore, the series energy storage unit also includes a single battery cell connected in parallel with the voltage regulator capacitor or a battery pack composed of multiple batteries connected in series.

[0054] Example 2 The difference between this embodiment and Embodiment 1 is that: The parallel energy storage unit also includes a bidirectional energy storage branch connected in parallel with the voltage stabilizing capacitor.

[0055] like Figure 7 As shown, in the bidirectional energy storage branch, S iBj5 S iBj6The IGBT switching transistors with freewheeling diodes form the bridge switching device of the bidirectional DC-DC converter. Bij This is the filter inductor for the energy storage side. LBij C is the inductor operating current. PVBij This is the voltage regulator capacitor for the energy storage battery. (V) PVBij I is the terminal voltage of the energy storage battery pack. PVBij The charging and discharging current of the energy storage battery.

[0056] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for optimizing power allocation in a three-phase photovoltaic-storage hybrid system, characterized in that, Includes the following steps: S1. Real-time acquisition of the total output power P of each photovoltaic unit in each phase of the three-phase circuit. pvi The output power P of the H-bridge module in each photovoltaic unit within each cascaded link pvij The remaining state of charge (SOC) of the battery modules in each energy storage unit. ij The grid-connected current of each phase circuit and the modulation ratio of the H-bridge module of each photovoltaic unit and each energy storage unit; S2. Calculate the total power imbalance difference P between phases in a three-phase circuit. DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi ; S3. Based on the magnitude of the imbalance difference, determine whether to activate the parallel or series energy storage unit and enter the corresponding mode range: if it is determined that parallel energy storage compensation or parallel energy storage self-recovery is adopted, then execute the control logic of one of modes 1-8; if it is determined that series energy storage compensation or series energy storage self-recovery is adopted, then execute the control logic of one of modes 9-16. S4. Real-time verification of the modulation ratio of the H-bridge module of each photovoltaic unit and each energy storage unit, avoiding over-modulation conditions throughout the process, and outputting a balanced modulated wave for grid connection.

2. The power optimization allocation method for a three-phase photovoltaic-storage hybrid system according to claim 1, characterized in that, When the total power imbalance difference between phases in a three-phase circuit is P DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi When the threshold is exceeded, the output active power of each energy storage unit is adjusted when switching to parallel or series energy storage compensation mode to ensure that the total output power P of each phase of the three-phase circuit is equal to that of the parallel or series energy storage compensation mode. pvi The output power P of the H-bridge module in each photovoltaic unit within the equal, single-phase cascaded link pvij equal.

3. The power optimization allocation method for a three-phase photovoltaic-storage hybrid system according to claim 2, characterized in that, The parallel energy storage compensation mode is one of modes 1-5, wherein mode 1 is the output power imbalance difference P of the H-bridge module in each photovoltaic unit within the i-th phase cascaded link. DPi The value equals 0, at which point the parallel energy storage unit B is controlled. ij Exit system operation; Mode 2 refers to the output power imbalance difference P of the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi >0, and the remaining SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is ij The SOC of the energy storage unit is greater than the lower threshold. min At this time, control the parallel energy storage unit B ij Entering discharge mode, the discharge power is P DPi Mode 3 refers to the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is greater than 0. ij Less than or equal to the lower threshold SOC of the energy storage unit min At this time, each parallel energy storage unit in phase i is controlled to exit system operation; the mode 4 is the output power imbalance difference P of the H-bridge module in each photovoltaic unit in the cascaded link of phase i. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is less than 0. ij less than the upper limit threshold SOC of the energy storage unit max At this time, control the parallel energy storage unit B ij Entering charging mode, charging power is P DPi Mode 5 refers to the output power imbalance difference P between the H-bridge modules in each photovoltaic unit within the i-th phase cascaded link. DPi The SOC of the energy storage unit corresponding to the i-th phase and the j-th H-bridge unit is less than 0. ij The SOC (State of Charge) of the energy storage unit is greater than or equal to the upper limit threshold. max At this point, each parallel energy storage unit in phase i is controlled to exit system operation.

4. The power optimization allocation method for a three-phase photovoltaic-storage hybrid system according to claim 2, characterized in that, One of the series energy storage compensation modes 9-13, wherein mode 9 is the phase-to-phase total power imbalance difference P of the three-phase circuit. DSi When the value equals 0, all series-connected energy storage units in phase i are shut down from system operation; mode 10 refers to the total power imbalance difference P between phases of the three-phase circuit. DSi The SOC of each energy storage unit in phase i is greater than 0 and is the average remaining energy value. Siavg less than the upper limit threshold SOC of the energy storage unit max At this time, all series-connected energy storage units in phase i are controlled to enter charging mode, and the total charging power is P. DSi Mode 11 refers to the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is greater than 0 and is the average remaining energy value. Siavg The SOC (State of Charge) of the energy storage unit is greater than or equal to the upper limit threshold. max At this time, all energy storage units in phase i are controlled to exit system operation; the mode 12 is the total power imbalance difference P between phases of the three-phase circuit. DSi The SOC of each energy storage unit in phase i is less than 0 and is the average remaining energy value. Siavg The SOC of the energy storage unit is greater than the lower threshold. min At this time, all series-connected energy storage units in phase i are controlled to enter discharge mode, and the total charging power is P. DSi Mode 13 refers to the phase-to-phase total power imbalance difference P in a three-phase circuit. DSi The SOC of each energy storage unit in phase i is less than 0 and is the average remaining energy value. Siavg Less than or equal to the lower threshold SOC of the energy storage unit min At this point, all energy storage units in phase i are controlled to exit system operation.

5. The power optimization allocation method for a three-phase photovoltaic-storage hybrid system according to claim 1, characterized in that, When the total power imbalance difference between phases in a three-phase circuit is P DSi The output power imbalance difference P of the H-bridge modules in each photovoltaic unit within a single-phase cascaded link. DPi When all are within a controllable range and the remaining SOC of the battery modules in the energy storage unit is lower than the lower threshold, the system switches to the energy storage self-recovery mode, controlling the surplus power of each photovoltaic unit in each phase circuit to charge the energy storage units connected in parallel or series, and simultaneously performing SOC equalization adjustment of the energy storage units on the single-phase cascaded link.

6. The power optimization allocation method for a three-phase photovoltaic-storage hybrid system according to claim 5, characterized in that, The parallel energy storage self-recovery mode is one of modes 6-8, where mode 6 is the total remaining energy (SOC) of all energy storage units in the i-th phase. i Equal to the total remaining power setting value (SOC) set At this point, all parallel energy storage units in phase i are controlled to exit system operation; mode 7 is the total remaining power SOC of all energy storage units in phase i. i Greater than the total remaining power setting (SOC) set At this time, control the parallel energy storage unit B ij Entering discharge mode; mode 8 is the total remaining charge (SOC) of each energy storage unit in phase i. i Less than or equal to the total remaining battery power setting (SOC) set At this time, control the parallel energy storage unit B ij Enter charging mode.

7. The power optimization allocation method for a three-phase photovoltaic-storage hybrid system according to claim 5, characterized in that, The series energy storage self-recovery mode is one of modes 14-16, where mode 14 is the average remaining charge (SOC) of each energy storage unit in the i-th phase. Siavg Equal to the total remaining power setting value (SOC) set At this point, all series-connected energy storage units in phase i are shut down from system operation; mode 15 is the average remaining charge (SOC) of each energy storage unit in phase i. Siavg Greater than the total remaining power setting (SOC) set At this time, all series-connected energy storage units in phase i are controlled to enter the discharge mode; the mode 16 is the average remaining charge (SOC) of each energy storage unit in phase i. Siavg Less than the total remaining battery power setting (SOC) set At this time, all series-connected energy storage units in phase i are controlled to enter charging mode.

8. A power optimization allocation system for a three-phase photovoltaic-storage hybrid system, used to implement the power optimization allocation method for a three-phase photovoltaic-storage hybrid system according to any one of claims 1-7, characterized in that, The system includes a three-phase circuit, each phase of which includes a photovoltaic unit, a series energy storage unit connected in series with the photovoltaic unit, and a parallel energy storage unit connected in parallel with the photovoltaic unit. Each photovoltaic unit, series energy storage unit, and parallel energy storage unit includes an H-bridge module and a voltage regulator capacitor. The H-bridge module is connected in parallel with the voltage regulator capacitor. The H-bridge module includes at least four IGBTs, each IGBT equipped with a freewheeling diode.

9. A power optimization allocation system for a three-phase photovoltaic-storage hybrid system according to claim 8, characterized in that, The series energy storage unit also includes a single battery cell connected in parallel with the voltage stabilizing capacitor or a battery pack composed of multiple batteries connected in series.

10. A power optimization allocation system for a three-phase photovoltaic-storage hybrid system according to claim 8, characterized in that, The parallel energy storage unit also includes a bidirectional DC-DC converter or a bidirectional energy storage branch connected in parallel with the voltage stabilizing capacitor.

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