Power coordination control method and device for single-phase cascaded optical storage hybrid system
By setting dual criteria of modulation factor and state of charge in a single-phase cascaded photovoltaic system, the operating modes of photovoltaic modules and battery cells are dynamically adjusted, thus solving the overmodulation risk caused by unbalanced photovoltaic power and achieving system performance stability and simplification.
Patent Information
- Application Number
- CN202511628524.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-07
- Publication Date
- 2026-02-10
AI Technical Summary
In existing single-phase cascaded photovoltaic systems, the power imbalance caused by the inconsistency between the light intensity received by the photovoltaic modules and the ambient temperature leads to a high risk of overmodulation and a complex system structure, which is difficult to manage economically and effectively with existing technologies.
By determining the modulation factor and the state of charge of the battery cells, four power coordination control strategies are set, including the operating modes of photovoltaic modules and battery cells, to dynamically adjust the charging and discharging power of the battery to stabilize the modulation factor and avoid overmodulation.
It simplifies the system hardware architecture, reduces the risk of overmodulation, maintains system performance, and effectively manages photovoltaic power imbalance without increasing complexity and cost.
Smart Images
Figure CN121507928A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photovoltaic system power control technology, and more specifically, to a method and apparatus for coordinated power control of a single-phase cascaded photovoltaic-storage hybrid system. Background Technology
[0002] Existing single-phase cascaded photovoltaic (PV) systems typically employ cascaded H-bridge multilevel converters (H-bridges) as their core power conversion architecture. This involves independently connecting PV modules to the DC side of each H-bridge module and then connecting them in series on the AC side to form a multilevel voltage output. This output is then filtered by a grid-connected filter inductor before being connected to the power grid. This structure effectively improves system efficiency and power density, thus demonstrating promising application prospects.
[0003] However, in actual operation, the aforementioned topology suffers from power imbalances due to the difficulty in maintaining consistent light intensity and ambient temperature across photovoltaic modules. To address issues such as overmodulation of the H-bridge modules, existing technologies have proposed solutions such as improved modulation strategies or the addition of energy storage modules. However, improved modulation strategies have inherent limitations in their ability to suppress overmodulation; while adding energy storage modules presents challenges such as complex system structure, high cost, and difficulty in control. Therefore, how to manage power imbalance economically and effectively while ensuring system performance has become a pressing technical challenge in this field. Summary of the Invention
[0004] The purpose of this invention is to provide a power coordination control method and device for a single-phase cascaded photovoltaic-storage hybrid system, which solves the technical problems of complex system structure and high overmodulation risk in the prior art. By simplifying the hardware architecture and maintaining system performance, the overmodulation risk caused by photovoltaic power imbalance is reduced.
[0005] In a first aspect, embodiments of the present invention provide a power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system. This method is applied to a single-phase cascaded photovoltaic-storage hybrid system, which includes, in sequence, a cascaded converter, a photovoltaic module unit, an isolated multi-port DC-DC converter unit, and a battery unit. The method includes: Based on the reference power and DC-side voltage of the photovoltaic module unit, and the reference amplitude of the output voltage of the cascade converter, determine the modulation factor of the cascade converter when the power of the battery unit is zero. Determine the magnitude of the modulation factor and the target threshold, and determine the magnitude of the state of charge of the battery cell and the range of the state of charge threshold to determine the comparison result; Based on the comparison results, a corresponding power coordination control strategy is determined to control the operating mode of the single-phase cascaded photovoltaic-storage hybrid system. The power coordination control strategy includes the operating mode of the photovoltaic module unit and the operating mode of the battery unit.
[0006] In some optional implementations, the photovoltaic module unit includes N photovoltaic modules; the cascaded converter includes N first bidirectional DC-AC converters and a grid-connected filter inductor; the isolated multi-port DC-AC converter includes N second bidirectional DC-AC converters, a third bidirectional DC-AC converter and a multi-winding transformer; The AC sides of N first bidirectional DC-AC converters are connected in series and then connected to the power grid through a grid-connected filter inductor; the DC sides of the N first bidirectional DC-AC converters are respectively connected to N photovoltaic modules. The DC ports of the N second bidirectional DC-AC converters are respectively connected to the N photovoltaic modules; the AC ports of the N second bidirectional DC-AC converters are connected through a multi-winding transformer; the DC port of the third bidirectional DC-AC converter is connected to the battery cell; the AC port of the third bidirectional DC-AC converter is connected to the multi-winding transformer.
[0007] In some optional implementations, the modulation factor is calculated using the following formula: ; in, Z 1i The modulation factor is represented by 1 ≤ i ≤ n; P * PVi This represents the reference power of the i-th photovoltaic module; P * PV This represents the sum of the reference power of N photovoltaic modules; V * C This indicates the reference amplitude of the output voltage of the cascaded converter; V PVi This represents the DC-side voltage of the i-th photovoltaic module.
[0008] In some optional implementations, a corresponding power coordination control strategy is determined based on the comparison results, including: When the comparison result is that the modulation factor is not greater than the target threshold and the state of charge of the battery cell is less than the upper limit of the state of charge threshold range, the power coordination control strategy is: the photovoltaic module cell operates in maximum power point tracking mode and the battery cell operates in charging mode. When the comparison result is that the modulation factor is not greater than the target threshold and the state of charge of the battery cell is not less than the upper limit of the state of charge threshold range, the power coordination control strategy is: the photovoltaic module cell operates in maximum power point tracking mode and the battery cell operates in exit system operation mode. When the comparison result shows that the modulation factor is greater than the target threshold and the state of charge of the battery cell is greater than the lower limit of the state of charge threshold range, the power coordination control strategy is as follows: the photovoltaic module cell operates in maximum power point tracking mode and the battery cell operates in discharge mode. When the comparison result shows that the modulation factor is greater than the target threshold and the state of charge of the battery cell is not greater than the lower limit of the state of charge threshold range, the power coordination control strategy is as follows: the photovoltaic module cell operates in the mode of exiting the maximum power point tracking mode, and the battery cell operates in the mode of exiting the system operation mode.
[0009] In some optional implementations, when the battery cell operates in the exit system operation mode, the reference power of the battery cell is... P * B =0; When the battery cell is operating in charging mode, the reference power of the battery cell P * B The calculation formula is: ; When the battery cell is operating in discharge mode, the reference power of the battery cell P * B The calculation formula is: ; in, P * PV This represents the sum of the reference power of N photovoltaic modules; P * PVmax Z represents the reference power of the photovoltaic module with the highest power generation. 1max This represents the modulation factor of the bidirectional DC-AC converter with the highest power generation in the cascaded converter when the power of the battery cell is zero.
[0010] In some optional implementations, the photovoltaic module unit operates in a mode such that when it exits maximum power point tracking mode, the reference power of the i-th photovoltaic module is... P * PVi The calculation formula is: ; in, P * PV V represents the sum of the reference power of N photovoltaic modules; pvi V represents the DC-side voltage of the i-th photovoltaic module; * CThis indicates the reference amplitude of the output voltage of the cascaded converter.
[0011] In some optional implementations, cascaded converters are used to control the operating mode of photovoltaic module units, and isolated multi-port DC-DC converter units are used to control the operating mode of battery units. In an isolated multi-port DC-DC converter, the reference power of the N second bidirectional DC-AC converters connected to N photovoltaic modules is equal.
[0012] In a second aspect, embodiments of the present invention provide a power coordination control device for a single-phase cascaded photovoltaic-storage hybrid system, used to execute the method described in any of the first aspects above. The device includes: a modulation factor determination module, used to determine the modulation factor of the cascaded converter when the power of the battery cell is zero, based on the reference power and DC side voltage of the photovoltaic module unit and the reference amplitude of the output voltage of the cascaded converter. The judgment module is used to judge the magnitude of the modulation factor and the target threshold, and to judge the magnitude of the state of charge of the battery cell and the range of the state of charge threshold, and to determine the comparison result. The control strategy determination module is used to determine the corresponding power coordination control strategy based on the comparison results, so as to control the operating mode of the single-phase cascaded photovoltaic-storage hybrid system. The power coordination control strategy includes the operating mode of the photovoltaic module unit and the operating mode of the battery unit.
[0013] Thirdly, embodiments of the present invention provide an electronic device, including a memory and a processor, wherein the memory stores a computer program that can run on the processor, and the processor executes the computer program to implement the steps of the method described in any of the first aspects above.
[0014] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer-executable instructions, which, when invoked and executed by a processor, cause the processor to perform the method described in any of the first aspects above.
[0015] This invention provides a power coordination control method and apparatus for a single-phase cascaded photovoltaic-storage hybrid system. The method includes: determining the modulation factor of the cascaded converter when the battery cell power is zero, based on the reference power and DC-side voltage of the photovoltaic module unit and the reference amplitude of the output voltage of the cascaded converter; comparing the modulation factor with a target threshold and the state of charge (SOC) of the battery cell with the SOC threshold range, and determining the comparison result; and based on the comparison result, determining a corresponding power coordination control strategy to control the operating mode of the single-phase cascaded photovoltaic-storage hybrid system. This method solves the technical problems of complex system structure and high overmodulation risk in existing technologies, achieving the technical effects of simplifying the hardware architecture while maintaining system performance and reducing overmodulation risk. Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 A topology diagram of a single-phase cascaded photovoltaic-storage hybrid system provided in an embodiment of the present invention; Figure 2 This is a topology diagram of a single-phase cascaded photovoltaic-storage hybrid system provided in a preferred embodiment of the present invention. Figure 3 A flowchart of a power control method for a single-phase cascaded photovoltaic-storage hybrid system provided in an embodiment of the present invention; Figure 4 An equivalent circuit diagram of a battery cell operating in charging mode in a single-phase cascaded photovoltaic-storage hybrid system provided for an embodiment of the present invention; Figure 5 An equivalent circuit diagram of a battery cell exiting system operation in a single-phase cascaded photovoltaic-storage hybrid system is provided for an embodiment of the present invention. Figure 6 An equivalent circuit diagram of a battery cell operating in discharge mode in a single-phase cascaded photovoltaic-storage hybrid system provided for an embodiment of the present invention; Figure 7 This is a flowchart of a power control method for a single-phase cascaded photovoltaic-storage hybrid system in a preferred embodiment of the present invention. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] In actual operation, the power generation of existing single-phase cascaded photovoltaic (PV) systems is inconsistent among PV modules connected to the DC side of the H-bridge module due to factors such as ambient temperature, solar radiation intensity, PV module shading area, and module consistency. When the power generation of each PV module differs significantly, the AC output voltage amplitude of the H-bridge module connected to the PV module with higher power generation is larger due to the series topology, posing a risk of over-modulation. Over-modulation will prevent the H-bridge module from fully transmitting the power generated by the PV modules to the grid, causing grid-connected current distortion, and in severe cases, even causing the PV grid-connected inverter to shut down.
[0020] Based on this, the present invention provides a power coordination control method and device for a single-phase cascaded photovoltaic-storage hybrid system, which can simplify the hardware architecture and maintain system performance, thereby solving the problems of complex system structure and high overmodulation risk, and thus reducing the overmodulation risk caused by photovoltaic power imbalance.
[0021] To facilitate understanding of this embodiment, a single-phase cascaded photovoltaic-storage hybrid system disclosed in this invention will first be described in detail. (See [link to relevant documentation]). Figure 1 The diagram shows a topology of a single-phase cascaded photovoltaic-storage hybrid system, which may include, in sequence, a cascaded converter, a photovoltaic module unit, an isolated multi-port DC-DC converter unit, and a battery unit.
[0022] The photovoltaic module unit includes N photovoltaic modules; the cascaded converter includes N first bidirectional DC-AC converters and a grid-connected filter inductor; the isolated multi-port DC-AC converter includes N second bidirectional DC-AC converters, a third bidirectional DC-AC converter and a multi-winding transformer.
[0023] The AC sides of N first bidirectional DC-AC converters are connected in series and then connected to the power grid via a grid-connected filter inductor; the DC sides of the N first bidirectional DC-AC converters are respectively connected to N photovoltaic modules; the DC ports of the N second bidirectional DC-AC converters are respectively connected to the N photovoltaic modules; the AC ports of the N second bidirectional DC-AC converters are connected via a multi-winding transformer; the DC port of the third bidirectional DC-AC converter is connected to a battery cell; the AC port of the third bidirectional DC-AC converter is connected to a multi-winding transformer.
[0024] See Figure 1 As shown, the cascaded converter consists of N first bidirectional DC-AC converters connected in series. After their AC sides are connected in series, they are filtered by a grid-connected filter inductor L. g Voltage source V connected to the power grid g Each first bidirectional DC-AC converter is connected to its corresponding photovoltaic module via a capacitor (C). 11 C 21 ...) connection. The DC side of the photovoltaic module is connected one-to-one with the DC side of each of the N first bidirectional DC-AC converters in the cascaded converter. Isolated multi-port DC-DC converter ( Figure 1 The multi-port isolated DC-DC converter in the middle) uses a capacitor (C) 12 C 22 ...) connected to photovoltaic modules; the isolated multi-port DC-DC converter also includes: N second bidirectional DC-AC converters and corresponding L1, L2...Ln connected thereto, as well as a multi-winding transformer L... B The AC ports of each of the N second bidirectional DC-AC converters are connected to the multi-winding transformer LB, and the DC ports are connected one-to-one with the aforementioned N photovoltaic modules. The voltage of the battery cell is indicated by V. B The battery cell is connected to capacitor C. B It is connected to the DC port of the third bidirectional DC-AC converter in the isolated multi-port DC-DC converter unit.
[0025] Furthermore, as a concrete example, Figure 2 A topology diagram of a single-phase cascaded photovoltaic-storage hybrid system in a preferred embodiment is shown. Each first bidirectional DC-AC converter in the cascaded converter can include four switching transistors (such as S...). 11 S 12 S 13 S 14 The H-bridge circuit unit consists of four switching transistors (such as S). Each second bidirectional DC-AC converter in an isolated multi-port DC-DC converter can include a second switching transistor consisting of four switching transistors (such as S). 15 S 16 S 17 S 18 The H-bridge circuit unit consists of N second bidirectional DC-AC converters, which are not directly connected in series but are each connected to L1, L2...Lr via Lr. n The third bidirectional DC-AC converter in the battery cell consists of T1, T2, T3, and T4.
[0026] The following section provides a detailed description of a power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system disclosed in an embodiment of the present invention. (See also...) Figure 3The diagram shows a power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system. This method is applied to the single-phase cascaded photovoltaic-storage hybrid system in the above embodiment. The method can be executed by electronic equipment and mainly includes the following steps S302 to S306: Step S302: Determine the modulation factor of the cascade converter when the power of the battery cell is zero, based on the reference power and DC side voltage of the photovoltaic module unit and the reference amplitude of the output voltage of the cascade converter.
[0027] The modulation factor essentially reflects the power distribution ratio and voltage modulation relationship of each converter unit, and its value directly affects whether the system needs battery intervention to balance the power.
[0028] In one embodiment, the modulation factor is calculated using the following formula: ;(Formula 1) in, Z 1i The modulation factor is represented by 1 ≤ i ≤ n; P * PVi This represents the reference power of the i-th photovoltaic module; P * PV This represents the sum of the reference power of N photovoltaic modules; V * C This indicates the reference amplitude of the output voltage of the cascaded converter; V PVi This represents the DC-side voltage of the i-th photovoltaic module.
[0029] Step S304: Determine the magnitude of the modulation factor and the target threshold, and determine the magnitude of the state of charge of the battery cell and the state of charge threshold range, and determine the comparison result.
[0030] In some implementations, the output power of the H-bridge module under power imbalance conditions can be increased by modifying its modulation strategy. However, its limitation is that the modulation factor of the H-bridge module can only be increased to a maximum value of 4 / π. When the modulation factor exceeds 4 / π, the H-bridge module will again face the overmodulation problem. Therefore, the aforementioned target threshold can be a predetermined fixed threshold, such as 4 / π.
[0031] In another implementation, the target threshold can be a dynamic threshold, which can be optimized and adjusted in real time by a threshold prediction model to adapt to dynamic environmental conditions. The threshold prediction model can be trained and adjusted based on historical operating data or real-time environmental parameters to generate a dynamic target threshold, thereby improving the accuracy of mode switching and system efficiency.
[0032] Threshold prediction models (such as machine learning models, deep learning models, or reinforcement learning models) can automatically adjust mode switching thresholds by learning from historical operational data or real-time environmental parameters, making the system more adaptable to dynamic environments. As a concrete example, the specific implementation of obtaining dynamic thresholds may include the following steps: (S301) Data Acquisition and Input: Acquire multi-source data as input to the threshold prediction model. This multi-source data may include historical photovoltaic power generation (e.g., P*PVi), DC side voltage (VPVi), battery state of charge (SOC) value, environmental parameters (e.g., irradiance, temperature), and historical records of operating modes. This data can be acquired in real time from system sensors or monitoring platforms to generate a time-series dataset.
[0033] (S302) Algorithm selection and training; Supervised learning processes can use regression models (such as support vector machines or neural networks) to train threshold prediction models. Inputs can include current environmental data and system states, with the output being the optimized threshold. Training data can come from historical best-case scenarios, where "best" is defined by metrics such as system efficiency and battery life. Furthermore, reinforcement learning processes more suitable for dynamic environments can be included, specifically implemented through trial-and-error learning optimization strategies. After training, the model can be deployed in electronic devices or the controller of a single-phase cascaded photovoltaic-storage hybrid system to achieve real-time threshold updates.
[0034] In addition, the state of charge threshold range can be dynamically optimized by combining external parameters. For example, in high-temperature environments, the upper limit of the state of charge threshold, SOCmax, can be lowered to prevent the battery from overheating, or in cloudy weather, the lower limit of the state of charge threshold, SOCmin, can be increased to ensure backup power.
[0035] Step S306: Based on the comparison results, determine the corresponding power coordination control strategy to control the operating mode of the single-phase cascaded photovoltaic-storage hybrid system; the power coordination control strategy includes: the operating mode of the photovoltaic module unit and the operating mode of the battery unit.
[0036] In this embodiment, the relationship between the modulation factor and the target threshold, and the relationship between the battery cell's state of charge (SOC) and the upper limit of the battery cell's SOC can be determined. max The relationship between the magnitudes, and the determination of the State of Charge (SOC) of the battery cell and the lower limit of the SOC of the battery cell. min Based on the magnitude relationship and the above judgment results, the single-phase cascaded photovoltaic-storage hybrid system is operated according to mode I, mode II, mode III and mode IV respectively.
[0037] (Mode I) When the comparison result is that the modulation factor is not greater than the target threshold and the state of charge of the battery cell is less than the upper limit of the state of charge threshold range, the power coordination control strategy is: the photovoltaic module cell operates in maximum power point tracking mode and the battery cell operates in charging mode.
[0038] When the photovoltaic module unit operates in the mode of exiting maximum power point tracking mode, the reference power of the i-th photovoltaic module is... P * PVi The calculation formula is: ;(Formula 2) in, P * PV V represents the sum of the reference power of N photovoltaic modules; pvi V represents the DC-side voltage of the i-th photovoltaic module; * C This indicates the reference amplitude of the output voltage of the cascaded converter.
[0039] Figure 4 This embodiment provides an equivalent circuit diagram of a battery cell operating in charging mode within a single-phase cascaded photovoltaic-storage hybrid system. When the battery cell operates in charging mode, the reference power of the battery cell is... P * B The calculation formula is: ;(Formula 3) in, P * PV This represents the sum of the reference power of N photovoltaic modules; P * PVmax Z represents the reference power of the photovoltaic module with the highest power generation. 1max This represents the modulation factor of the bidirectional DC-AC converter with the highest power generation in the cascaded converter when the power of the battery cell is zero.
[0040] (Mode II) When the comparison result is that the modulation factor is not greater than the target threshold and the state of charge of the battery cell is not less than the upper limit of the state of charge threshold range, the power coordination control strategy is: the photovoltaic module cell operates in maximum power point tracking mode and the battery cell operates in exit system operation mode.
[0041] Figure 5 This embodiment provides an equivalent circuit diagram of a battery cell in a single-phase cascaded photovoltaic-storage hybrid system when it exits system operation. Correspondingly, when the battery cell operates in the exit system operation mode, the reference power of the battery cell is... P* B =0.
[0042] (Mode III) When the comparison result is that the modulation factor is greater than the target threshold and the state of charge of the battery cell is greater than the lower limit of the state of charge threshold range, the power coordination control strategy is: the photovoltaic module cell operates in maximum power point tracking mode and the battery cell operates in discharge mode.
[0043] Figure 6 This embodiment provides an equivalent circuit diagram of a battery cell operating in discharge mode within a single-phase cascaded photovoltaic-storage hybrid system. When the battery cell operates in discharge mode, the reference power of the battery cell is... P * B The calculation formula is: ;(Formula 4) in, P * PV This represents the sum of the reference power of N photovoltaic modules; P * PVmax Z represents the reference power of the photovoltaic module with the highest power generation. 1max This represents the modulation factor of the bidirectional DC-AC converter with the highest power generation in the cascaded converter when the power of the battery cell is zero.
[0044] (Mode IV) When the comparison result is that the modulation factor is greater than the target threshold and the state of charge of the battery cell is not greater than the lower limit of the state of charge threshold range, the power coordination control strategy is: the working mode of the photovoltaic module cell is to exit the maximum power point tracking mode, and the working mode of the battery cell is to exit the system operation mode.
[0045] In the above embodiments, controlling the photovoltaic module to operate in maximum power point tracking mode and controlling the photovoltaic module to exit maximum power point tracking mode are achieved by a cascaded converter; controlling the battery cell to operate in charging mode, controlling the battery cell to exit system operation, and controlling the battery cell to operate in discharging mode are achieved by an isolated multi-port DC-DC converter.
[0046] In an isolated multi-port DC-DC converter, the N second bidirectional DC-AC converters connected to N photovoltaic modules have equal reference power. That is, the reference power of each second bidirectional DC-AC converter is equal.
[0047] As a concrete example, see Figure 7 The flowchart shown represents a power control method for a single-phase cascaded photovoltaic-storage hybrid system in a preferred embodiment. This method may include the following steps: Step X1: Calculate the power output of the cascaded converter when the battery cell power is zero. N Modulation factor of a bidirectional DC-AC converter Z 1i (1≤ i ≤ n The calculation formula is: (Formula 1) in, P * PVi Indicates the first i Reference power of each photovoltaic module P * PV Indicates all n The sum of the reference power of each photovoltaic module, V * C This indicates the reference amplitude of the output voltage of the cascaded converter. V PVi Indicates the first i DC-side voltage of each photovoltaic module; Step X2: Determine the modulation factor Z 1i The relationship between the value of 4 / π and the value of π is used to determine the state of charge (SOC) of the battery cell and the upper limit of the SOC for battery cell operation. max The relationship between the magnitudes of the states of charge (SOC) and the lower limit of the battery cell's state of charge (SOC) is used to determine the relative values of the SOC and the battery cell's state of charge. min Based on the above judgment results and considering the magnitude relationship, the single-phase cascaded photovoltaic-storage hybrid system operates according to Mode I, Mode II, Mode III, and Mode IV, respectively: Step X2.1: If the modulation factor Z 1i ≤4 / π, SOC <SOC max The single-phase cascaded photovoltaic-storage hybrid system operates in mode I, controlling the photovoltaic modules to operate in maximum power point tracking mode and controlling the battery cells to operate in charging mode.
[0048] Step X2.2: If Z 1i ≤4 / π, SOC≥SOC max The single-phase cascaded photovoltaic-storage hybrid system operates in Mode II, controlling the photovoltaic modules to operate in maximum power point tracking mode and controlling the battery cells to exit system operation.
[0049] Step X2.3: If Z 1i >4 / π, SOC>SOC minThe single-phase cascaded photovoltaic-storage hybrid system operates in mode III, controlling the photovoltaic modules to operate in maximum power point tracking mode and controlling the battery cells to operate in discharge mode.
[0050] Step X2.4: If Z 1i >4 / π, SOC≤SOC min The single-phase cascaded photovoltaic-storage hybrid system operates in mode IV, controlling the photovoltaic modules to exit maximum power point tracking mode and controlling the battery cells to exit system operation.
[0051] In summary, this invention provides a power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system. At the control strategy level, this method establishes four operating modes based on dual criteria of modulation factor and battery state of charge (SOC). This strategy can dynamically adjust the charging and discharging power of the battery or the output power of the photovoltaic system, thereby intelligently stabilizing the modulation factor of each H-bridge within a safe range, thus avoiding overmodulation and ensuring the autonomous safety management of the battery. Furthermore, without excessively increasing system complexity and manufacturing costs, it can reliably and effectively solve the problem of unbalanced photovoltaic power.
[0052] Based on the same inventive concept, this invention also provides a power coordination control device for a single-phase cascaded photovoltaic-storage hybrid system, used to execute the method described in any of the above embodiments. This device mainly includes the following components: The modulation factor determination module is used to determine the modulation factor of the cascaded converter when the power of the battery cell is zero, based on the reference power and DC side voltage of the photovoltaic module unit and the reference amplitude of the output voltage of the cascaded converter. The judgment module is used to judge the magnitude of the modulation factor and the target threshold, and to judge the magnitude of the state of charge of the battery cell and the range of the state of charge threshold, and to determine the comparison result. The control strategy determination module is used to determine the corresponding power coordination control strategy based on the comparison results, so as to control the operating mode of the single-phase cascaded photovoltaic-storage hybrid system. The power coordination control strategy includes the operating mode of the photovoltaic module unit and the operating mode of the battery unit.
[0053] The device provided in this embodiment of the invention has the same implementation principle and technical effect as the aforementioned method embodiment. For the sake of brevity, any parts not mentioned in the device embodiment can be referred to the corresponding content in the aforementioned method embodiment.
[0054] Based on the same inventive concept, embodiments of the present invention also provide an electronic device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus, and the processor executes the machine-readable instructions to perform the steps of the method described above.
[0055] Specifically, the aforementioned memory and processor can be general-purpose memory and processor, without any specific limitations. When the processor runs a computer program stored in the memory, it can execute the above method.
[0056] The processor may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above methods can be completed by integrated logic circuits in the processor's hardware or by software instructions. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method.
[0057] Corresponding to the above method, this embodiment of the invention also provides a computer-readable storage medium storing machine-executable instructions. When the computer-executable instructions are called and run by a processor, the computer-executable instructions cause the processor to perform the steps of the above method.
[0058] The apparatus provided in this embodiment of the invention can be specific hardware on a device or software or firmware installed on the device. The implementation principle and technical effects of the apparatus provided in this embodiment of the invention are the same as those in the foregoing method embodiments. For the sake of brevity, any parts not mentioned in the apparatus embodiments can be referred to the corresponding content in the foregoing method embodiments. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, apparatuses, and units described above can all be referred to the corresponding processes in the above method embodiments, and will not be repeated here.
[0059] In the embodiments provided by this invention, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and there may be other division methods in actual implementation. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the coupling or direct coupling or communication connection shown or discussed may be through some communication interface; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.
[0060] For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.
[0061] 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.
[0062] In addition, the functional units in the embodiments provided by 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.
[0063] If a function 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 this invention, or the part that contributes to the prior art, or a 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 an electronic device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of this 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.
[0064] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0065] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0066] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0067] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, 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 the present invention. All should be covered within the scope of protection of the present invention.
Claims
1. A power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system, characterized in that, A method is applied to a single-phase cascaded photovoltaic-storage hybrid system, the system comprising, in sequence: a cascaded converter, a photovoltaic module unit, an isolated multi-port DC-DC converter unit, and a battery unit; the method includes: Based on the reference power and DC-side voltage of the photovoltaic module unit, and the reference amplitude of the output voltage of the cascade converter, determine the modulation factor of the cascade converter when the power of the battery unit is zero; The magnitude of the modulation factor and the target threshold are determined, and the magnitude of the state of charge of the battery cell and the state of charge threshold range are determined, and the comparison result is determined. Based on the comparison results, a corresponding power coordination control strategy is determined to control the operating mode of the single-phase cascaded photovoltaic-storage hybrid system; the power coordination control strategy includes: the operating mode of the photovoltaic module unit and the operating mode of the battery unit.
2. The power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system according to claim 1, characterized in that, The photovoltaic module unit includes N photovoltaic modules; the cascaded converter includes N first bidirectional DC-AC converters and a grid-connected filter inductor; the isolated multi-port DC-AC converter includes N second bidirectional DC-AC converters, a third bidirectional DC-AC converter, and a multi-winding transformer; The AC sides of the N first bidirectional DC-AC converters are connected in series and then connected to the power grid through the grid-connected filter inductor; the DC sides of the N first bidirectional DC-AC converters are respectively connected to the N photovoltaic modules. The DC ports of the N second bidirectional DC-AC converters are respectively connected to the N photovoltaic modules; the AC ports of the N second bidirectional DC-AC converters are connected through the multi-winding transformer; the DC port of the third bidirectional DC-AC converter is connected to the battery cell; the AC port of the third bidirectional DC-AC converter is connected to the multi-winding transformer.
3. The power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system according to claim 2, characterized in that, The formula for calculating the modulation factor is: ； in, Z 1i The modulation factor is represented by 1 ≤ i ≤ n; P * PVi This represents the reference power of the i-th photovoltaic module; P * PV This represents the sum of the reference power of the N photovoltaic modules; V * C This represents the reference amplitude of the output voltage of the cascaded converter; V PVi This represents the DC-side voltage of the i-th photovoltaic module.
4. The power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system according to claim 2, characterized in that, Based on the comparison results, the corresponding power coordination control strategy is determined, including: When the comparison result indicates that the modulation factor is not greater than the target threshold and the state of charge of the battery cell is less than the upper limit of the state of charge threshold range, the power coordination control strategy is as follows: the photovoltaic module unit operates in maximum power point tracking mode and the battery cell operates in charging mode. When the comparison result is that the modulation factor is not greater than the target threshold and the state of charge of the battery cell is not less than the upper limit of the state of charge threshold range, the power coordination control strategy is: the working mode of the photovoltaic module is maximum power point tracking mode, and the working mode of the battery cell is exit system operation mode. When the comparison result is that the modulation factor is greater than the target threshold and the state of charge of the battery cell is greater than the lower limit of the state of charge threshold range, the power coordination control strategy is: the photovoltaic module unit operates in maximum power point tracking mode and the battery cell operates in discharge mode. When the comparison result is that the modulation factor is greater than the target threshold and the state of charge of the battery cell is not greater than the lower limit of the state of charge threshold range, the power coordination control strategy is: the working mode of the photovoltaic module is to exit the maximum power point tracking mode, and the working mode of the battery cell is to exit the system operation mode.
5. The power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system according to claim 4, characterized in that, When the battery cell operates in the system exit mode, the reference power of the battery cell is... P * B =0; When the battery cell is in charging mode, the reference power of the battery cell is... P * B The calculation formula is: ； When the battery cell operates in discharge mode, the reference power of the battery cell is... P * B The calculation formula is: ； in, P * PV This represents the sum of the reference power of N photovoltaic modules; P * PVmax Z represents the reference power of the photovoltaic module with the highest power generation. 1max This indicates the modulation factor of the bidirectional DC-AC converter with the highest power generation in the cascaded converter when the power of the battery cell is zero.
6. The power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system according to claim 4, characterized in that, When the photovoltaic module unit operates in the mode of exiting maximum power point tracking mode, the reference power of the i-th photovoltaic module is... P * PVi The calculation formula is: ； in, P * PV V represents the sum of the reference power of N photovoltaic modules; pvi V represents the DC-side voltage of the i-th photovoltaic module; * C This represents the reference amplitude of the output voltage of the cascaded converter.
7. The power coordination control method for a single-phase cascaded photovoltaic-storage hybrid system according to claim 6, characterized in that, The cascaded converter is used to control the operating mode of the photovoltaic module unit, and the isolated multi-port DC-DC converter unit is used to control the operating mode of the battery unit. The reference power of the N second bidirectional DC-AC converters connected to the N photovoltaic modules in the isolated multi-port DC-DC converter is equal.
8. A power coordination control device for a single-phase cascaded photovoltaic-storage hybrid system, characterized in that, The apparatus for performing the method according to any one of claims 1 to 7, the apparatus comprising: The modulation factor determination module is used to determine the modulation factor of the cascade converter when the power of the battery cell is zero, based on the reference power and DC side voltage of the photovoltaic module unit and the reference amplitude of the output voltage of the cascade converter. The judgment module is used to judge the magnitude of the modulation factor and the target threshold, and to judge the magnitude of the state of charge of the battery cell and the state of charge threshold range, and to determine the comparison result; The control strategy determination module is used to determine the corresponding power coordination control strategy based on the comparison results, so as to control the operating mode of the single-phase cascaded photovoltaic-storage hybrid system; the power coordination control strategy includes: the operating mode of the photovoltaic module unit and the operating mode of the battery unit.
9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method described in any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions that, when invoked and executed by a processor, cause the processor to perform the method according to any one of claims 1 to 7.