A photovoltaic energy storage DC bus segmented high-frequency transformer access method and system

Abstract

The present invention discloses a photovoltaic energy storage DC bus segmented high-frequency transformer access method and system, which relates to the field of photovoltaic power generation and energy storage technology, including connecting a photovoltaic array and an energy storage unit to a DC bus, segmenting the DC bus, and connecting each segment of the DC bus to a power grid through a high-frequency transformer; collecting voltage and current data of each segmented DC bus, and adjusting the transformation ratio and switching frequency of each high-frequency transformer according to the collected data; collecting system operation data, planning the operation mode of each segment according to the system operation data, and adjusting the power distribution of each segment at different time periods, and adjusting the charging and discharging power of the energy storage unit; monitoring the operation status of the photovoltaic energy storage system, and isolating the faulty segment when a fault is detected. The present invention improves the safety and stability of the system, and the overall system realizes efficient, stable, and safe energy management and intelligent control, and has innovative and practical value.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation and energy storage, and in particular to a method and system for accessing photovoltaic energy storage DC bus segmented high-frequency transformer. Background Art

[0002] With the rapid development of photovoltaic power generation and energy storage technology, photovoltaic energy storage systems are increasingly being used in power systems. Traditional photovoltaic energy storage systems usually use centralized inverters to convert DC power into AC power before connecting to the grid. This approach has problems such as poor flexibility and low reliability.

[0003] At present, some photovoltaic energy storage systems use DC busbars to connect photovoltaic arrays and energy storage units, and connect to the grid through high-power inverters. Although this method improves the flexibility of the system, it still has the following problems: 1) A single inverter failure will cause the entire system to fail; 2) It is difficult to adapt to power distribution under different light and load conditions; 3) The system has poor scalability.

[0004] Therefore, a new access method for photovoltaic energy storage systems is urgently needed to improve the flexibility, reliability and scalability of the system and achieve efficient interconnection between photovoltaic energy storage systems and the power grid. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a photovoltaic energy storage DC bus segmented high-frequency transformer access method and system, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a method for accessing a photovoltaic energy storage DC busbar by segmented high-frequency transformation, which comprises connecting a photovoltaic array and an energy storage unit to a DC busbar, segmenting the DC busbar, and connecting each segment of the DC busbar to a power grid via a high-frequency transformer;

[0010] Collect the voltage and current data of each segment and the grid side, and adjust the transformation ratio and switching frequency of each high-frequency transformer according to the collected voltage and current data;

[0011] Collecting photovoltaic energy storage operation data, and planning the operation mode of each segment according to the photovoltaic energy storage operation data, adjusting the power allocation of each segment at different time periods, and adjusting the charging and discharging power of the energy storage unit;

[0012] Monitor the operating status of the photovoltaic energy storage system and isolate the faulty segment when a fault is detected.

[0013] As a preferred solution of the photovoltaic energy storage DC bus segmented high-frequency transformer access method of the present invention, wherein: the segmentation includes:

[0014] According to the distribution of photovoltaic arrays and energy storage units, the DC busbar is divided into multiple electrically independent sections; isolation switches are set between each section.

[0015] As a preferred solution of the photovoltaic energy storage DC bus segmented high-frequency transformer access method of the present invention, wherein: the adjustment of the transformation ratio and switching frequency of each high-frequency transformer includes:

[0016] The power of each segment is calculated according to the voltage and current data, and the transformation ratio of the corresponding high-frequency transformer is adjusted according to the power of each segment and the grid-side voltage. The calculation formula is as follows:

[0017]

[0018] Where n is the transformation ratio, λ 1 is the correction factor, P dc is the DC side power, P ac is the AC side power, V ac is the grid voltage, V dc is the DC bus voltage;

[0019] According to the power fluctuation of each segment, adjust the switching frequency of the corresponding high-frequency transformer. The calculation formula is as follows:

[0020]

[0021] Where f is the adjusted switching frequency, f 0 is the reference frequency, λ 2 is the adjustment coefficient, ΔP is the power fluctuation, P rated is the rated power.

[0022] As a preferred solution of the photovoltaic energy storage DC bus segmented high-frequency transformer access method described in the present invention, the photovoltaic energy storage operation data includes the real-time output power data of the photovoltaic array, the real-time power consumption data of each load point and the current charge state of the energy storage unit; the operation modes of each segment are planned to include photovoltaic power generation sufficient mode, load peak mode, energy storage charging mode, energy storage discharging mode and grid balance mode.

[0023] As a preferred solution of the photovoltaic energy storage DC bus segmented high-frequency transformer access method of the present invention, wherein: the power distribution of each segment is adjusted,

[0024] During system operation, the power distribution of each segment is adjusted according to the operation mode of the current period. The calculation formula is as follows:

[0025]

[0026] Among them, P i is the allocated power of the ith segment, P total is the total power, w i is the weight factor of the i-th segment, S i is the capacity of the i-th segment, Σ(w j *S j ) is the sum of weighted capacities of all segments;

[0027] The step of adjusting the charging and discharging power of the energy storage unit includes:

[0028] Real-time monitoring of the charge state of the energy storage unit;

[0029] According to the charge state of the energy storage unit and the system operation requirements, the charging and discharging of the energy storage unit is controlled. The calculation formula is as follows:

[0030] P b =(SOC-SOC ref )·k+(P gen -P load )·β 2

[0031] Among them, P b is the charging and discharging power of the energy storage unit, SOC is the current state of charge, SOC ref is the target state of charge, k is the proportionality coefficient, P gen is the power generation, P load is the load power, β 2 is the balance coefficient.

[0032] As a preferred solution of the photovoltaic energy storage DC bus segmented high-frequency transformer access method of the present invention, wherein: when a fault is detected, isolating the fault segment includes:

[0033] Continuously monitor the voltage and current data of each segment;

[0034] The fault index is calculated based on the voltage and current data of each segment. The calculation formula is as follows:

[0035]

[0036] Where F is the fault indicator, V is the measured voltage, V n is the rated voltage, I is the measured current, I n is the rated current;

[0037] When the fault index F exceeds the fault threshold, it is judged as a fault;

[0038] Control the disconnectors at both ends of the faulty section to disconnect and isolate the faulty section from the system;

[0039] Adjust the parameters of high-frequency transformers in other normal sections to maintain system stability.

[0040] As a preferred solution of the photovoltaic energy storage DC bus segmented high-frequency transformer access method of the present invention, the fault threshold is determined by a dynamic adjustment method, and the specific steps include:

[0041] Set the initial fault threshold F according to system characteristics t ;

[0042] Continuously collect system operation data;

[0043] Use the sliding window method to analyze the data of the last N time points;

[0044] Calculate the average value μ of the data in the sliding window F , standard deviation σ F , skewness S F And the kurtosis K F ;

[0045] The fault threshold is adjusted dynamically, and the adjustment formula is as follows:

[0046]

[0047] Among them, α 1 , β 1 , γ 1 is the adjustment coefficient, is the threshold before updating, is the updated threshold, σ F,ref is the reference standard deviation;

[0048] Regularly calculate the system's false alarm rate P false and the false negative rate P miss ;

[0049] And readjust the fault threshold according to the false alarm rate and missed alarm rate;

[0050] Every fixed time period t 0 , repeat the above steps.

[0051] In a second aspect, the present invention provides a photovoltaic energy storage DC bus segmented high-frequency transformer access system, which includes: a photovoltaic array connection module, a data acquisition and adjustment module, a power distribution module, and a fault monitoring and isolation module;

[0052] The photovoltaic array connection module is used to connect the photovoltaic array and the energy storage unit to the DC busbar, segment the DC busbar, and connect each segment of the DC busbar to the power grid through a high-frequency transformer;

[0053] The data acquisition and adjustment module is used to collect voltage and current data of each segment and the grid side, and adjust the transformation ratio and switching frequency of each high-frequency transformer according to the collected voltage and current data;

[0054] The power allocation module is used to collect photovoltaic energy storage operation data, and plan the operation mode of each segment according to the photovoltaic energy storage operation data, adjust the power allocation of each segment at different time periods, and adjust the charging and discharging power of the energy storage unit;

[0055] The fault monitoring and isolation module is used to monitor the operating status of the photovoltaic energy storage system and isolate the fault segment when a fault is detected.

[0056] In a third aspect, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, the steps of the photovoltaic energy storage DC bus segmented high-frequency transformation access method are implemented.

[0057] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, the steps of a method for implementing segmented high-frequency transformer access to a photovoltaic energy storage DC bus are implemented.

[0058] Compared with the prior art, the beneficial effect of the present invention is that the present invention connects the photovoltaic array and the energy storage unit to the DC busbar and segments them, and uses a high-frequency transformer to achieve efficient transmission and distribution of electric energy, effectively reducing transmission losses and improving system energy efficiency. By collecting and adjusting the voltage and current data of each segment, the system parameters can be optimized in real time, maintaining efficient and stable operation, and responding to load changes and voltage fluctuations; the operation data collection and power distribution module intelligently schedules the system operation mode to ensure the best power distribution in different modes, improve overall efficiency and extend equipment life; the fault monitoring and isolation module quickly responds to and handles faults to prevent fault spread and improve system safety and stability; the overall system realizes efficient, stable and safe energy management and intelligent control, and has innovative and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0060] Figure 1 A method flow chart of a photovoltaic energy storage DC bus segmented high-frequency transformer access method and system provided by an embodiment of the present invention;

[0061] Figure 2 An internal structural diagram of a computer device of a photovoltaic energy storage DC bus segmented high-frequency transformer access method and system provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to make the above-mentioned purposes, features and advantages of the present invention more understandable, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0063] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0064] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0065] Example 1

[0066] Reference Figure 1-Figure 2 , which is the first embodiment of the present invention, provides a photovoltaic energy storage DC bus segmented high-frequency transformer access method, including:

[0067] Before describing the embodiments of the present application in detail, some related concepts are first explained for the sake of clarity.

[0068] Dynamic Transformation Ratio Adjustment: Dynamic transformation ratio adjustment is a technology that optimizes the performance of high-frequency transformers in real time. In this system, the transformation ratio n is dynamically calculated using a formula that includes a correction factor k. The correction factor k is not a fixed value, but a parameter that is adjusted in real time based on system operating data, power range, temperature, etc. This dynamic adjustment method can adapt to instantaneous changes in the system, improve power transmission efficiency, and optimize the dynamic response characteristics of the system.

[0069] Sliding Window Fault Analysis: Sliding Window Fault Analysis is an advanced fault detection method. This method uses sliding window technology to analyze the system operation data of the last N time points, including voltage, current and fault indicators. By calculating the statistical characteristics of the data in this window (such as mean, standard deviation, skewness and kurtosis), the system can more accurately determine the fault status. This method can effectively reduce false positives and false negatives, improve the accuracy of fault detection and the reliability of the system.

[0070] Multi-mode adaptive operation strategy: Multi-mode adaptive operation strategy is an intelligent system management method. This strategy dynamically selects the most suitable operation mode based on real-time collected system operation data, such as photovoltaic output power, load demand, energy storage unit charge state, etc. The system includes a variety of preset modes, such as photovoltaic power generation sufficient mode, load peak mode, energy storage charging / discharging mode, etc. By setting the lag time and minimum interval time of mode switching, this strategy can avoid frequent switching caused by short-term fluctuations and ensure the stability of system operation. At the same time, it can also automatically enter the emergency mode according to the state of the power grid, give priority to ensuring the power supply of critical loads, and improve the flexibility and reliability of the system.

[0071] The present invention aims to solve the deficiencies of existing photovoltaic energy storage systems in terms of flexibility, reliability and scalability, especially how to achieve efficient interconnection and intelligent operation of the system through DC bus segmentation and high-frequency transformer access methods.

[0072] The present application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to explain in detail how to implement the photovoltaic energy storage DC bus segmented high-frequency transformer access method;

[0073] Figure 1 A method flow chart of a photovoltaic energy storage DC bus segmented high-frequency transformer access method and system is shown, including:

[0074] S1: Connect the photovoltaic array and the energy storage unit to a DC busbar, divide the DC busbar into sections, and connect each section to the grid via a high-frequency transformer.

[0075] In this step, the photovoltaic array and the energy storage unit are connected to the DC busbar through a DC / DC converter to form a DC microgrid system;

[0076] The voltage level of the DC busbar can be selected according to actual needs, for example, ±375V or ±750V can be selected.

[0077] In this step, the DC busbar is divided into a plurality of electrically independent segments according to the distribution of the photovoltaic array and the energy storage unit;

[0078] An isolating switch is provided between each section to isolate each section when necessary;

[0079] Each segment is connected to the grid via a high-frequency transformer; the operating frequency of the high-frequency transformer can be selected within the range of 1kHz-100kHz, and the specific frequency can be determined according to the power level and efficiency requirements.

[0080] S2: Collecting voltage and current data of each segment and the grid side, and dynamically adjusting the transformation ratio and switching frequency of each high-frequency transformer according to the voltage and current data.

[0081] In this step, a voltage sensor and a current sensor are set in each segment, and the voltage and current data of each segment are collected in real time through these sensors;

[0082] The collected data is transmitted to the central controller through the communication network; the sampling frequency can be determined according to the requirements of the system dynamic characteristics, for example, a sampling frequency of 1kHz-10kHz can be selected;

[0083] In this step, the central controller calculates the power of each segment based on the collected voltage and current data;

[0084] Then, according to the power of each segment and the grid-side voltage, the transformation ratio of the corresponding high-frequency transformer is adjusted to achieve the best power transmission efficiency;

[0085] At the same time, according to the power fluctuation of each segment, the switching frequency of the corresponding high-frequency transformer is adjusted to optimize the dynamic response characteristics of the system;

[0086] According to the collected voltage and current data, the power of each segment is calculated, including:

[0087] According to the power of each segment and the grid-side voltage, adjust the transformation ratio of the corresponding high-frequency transformer. The calculation formula is as follows:

[0088]

[0089] Where n is the transformation ratio, λ 1 is the correction factor (usually between 0.9 and 1.1), P dc is the DC side power, P ac is the AC side power, V ac is the grid voltage, V dcis the DC bus voltage.

[0090] According to the power fluctuation of each segment, adjust the switching frequency of the corresponding high-frequency transformer. The calculation formula is as follows:

[0091]

[0092] Where f is the adjusted switching frequency, f 0 is the reference frequency (such as 10kHz), λ 2 is the adjustment coefficient (such as 0.2), ΔP is the power fluctuation, P rated is the rated power.

[0093] S3: Collect photovoltaic energy storage operation data in real time, plan the operation mode of each segment according to the photovoltaic energy storage operation data, adjust the power allocation of each segment in different time periods, and adjust the charging and discharging power of the energy storage unit in real time.

[0094] Furthermore, the photovoltaic energy storage operation data includes the real-time output power data of the photovoltaic array, the real-time power consumption data of each load point, and the current charge state of the energy storage unit;

[0095] Furthermore, the operation modes of each segment are planned to include:

[0096] The system operation data pre-plans the operation mode of each segment at different time periods;

[0097] Determine the current operating status of the system based on the processed real-time data and select the corresponding operating mode;

[0098] The operation modes include sufficient photovoltaic power generation mode, peak load mode, energy storage charging mode, energy storage discharging mode and grid balancing mode;

[0099] Select the corresponding operation mode including:

[0100] When the photovoltaic output is significantly higher than the load demand, the photovoltaic power generation sufficient mode is started. This mode gives priority to the use of photovoltaic power, and the excess power is used for energy storage charging or feeding the grid;

[0101] When the load demand is significantly higher than the PV output, the peak load mode is activated, which uses PV, energy storage and grid power to meet the high load demand.

[0102] When the photovoltaic output exceeds the load demand and the energy storage SOC is low, the energy storage charging mode is started. This mode uses the excess photovoltaic power for energy storage charging;

[0103] When the load demand exceeds the photovoltaic output and the energy storage SOC is sufficient, the energy storage discharge mode is started. This mode uses the energy storage power to supplement the insufficient photovoltaic power.

[0104] When the photovoltaic output is basically balanced with the load demand and the grid parameters are normal, the grid balancing mode is started. This mode maintains stable operation of the system and minimizes power exchange with the grid.

[0105] Mode switching strategies include,

[0106] Set the hysteresis time for mode switching (e.g. 30 seconds) to avoid frequent switching due to short-term fluctuations;

[0107] Set a minimum interval time (e.g. 5 minutes) between mode switching to ensure the stability of system operation;

[0108] When a power grid anomaly is detected, the system may enter emergency mode to prioritize power supply to critical loads.

[0109] Further, adjusting the power allocation of each segment includes,

[0110] During system operation, the power distribution of each segment is adjusted according to the operation mode of the current period. The calculation formula is as follows:

[0111]

[0112] Among them, P i is the allocated power of the ith segment, P total is the total power, w i is the weight factor of the i-th segment, S i is the capacity of the i-th segment, Σ(w j *S j ) is the sum of weighted capacities of all segments.

[0113] Furthermore, real-time adjustment of the charging and discharging power of the energy storage unit includes:

[0114] Real-time monitoring of the charge state of the energy storage unit;

[0115] According to the charge state of the energy storage unit and the system operation requirements, the charging and discharging of the energy storage unit is controlled. The calculation formula is as follows:

[0116] P b =(SOC-SOC ref )·k+(P gen -P load )·β 2

[0117] Among them, P b is the charging and discharging power of the energy storage unit, SOC is the current state of charge, SOC ref is the target state of charge, k is the proportionality coefficient, P gen is the power generation, P load is the load power, β2 is the balance coefficient.

[0118] Furthermore, the selection method of the correction coefficient k includes:

[0119] The initial value of k is set to 1; this means that ideally, the transformation ratio n is directly determined by the power ratio and the voltage ratio;

[0120] According to the system loss, the k value is initially set between 1.02 and 1.05;

[0121] Dynamically adjust the k value according to the actual operation data. The adjustment formula is as follows:

[0122]

[0123] Among them, k new is the updated k value, k old is the current k value, α 2 is the learning rate, P actual is the actual measured power transfer value, P expected is the expected power transfer value;

[0124] Set different k values ​​according to different power ranges and limit the k value to a certain range, including 0.95≤k≤1.1. Set different k values, such as

[0125] When 0≤P dc <0.2P rated When k = 1.05;

[0126] When 0.2P rated ≤P dc <0.8P rated When k = 1.02;

[0127] When 0.8P rated ≤P dc ≤P rated When k = 1.00, P rated is the system rated power;

[0128] Regularly calibrate the k value based on system operation data;

[0129] Introducing the temperature correction factor, the calculation formula is as follows:

[0130] k=k 0 ·(1+γ 2 ·(TT ref )

[0131] Among them, k 0 is the k value at the reference temperature, γ 2 is the temperature coefficient, T is the current temperature, Tref is the reference temperature;

[0132] The k value is calibrated periodically (such as monthly or quarterly) based on the system operation data to adapt to the system's characteristics that change over time.

[0133] S4: Monitor the operating status of the PV energy storage system in real time and isolate the faulty section when a fault is detected.

[0134] In this step, the central controller continuously monitors the voltage and current data of each segment; when the voltage or current of a segment is detected to be abnormal, it is determined that the segment is faulty; the isolating switches at both ends of the segment are controlled to disconnect to isolate the faulty segment from the system; at the same time, the high-frequency transformer parameters of other normal segments are adjusted to ensure stable operation of the system;

[0135] Further, isolating the faulty segment upon detecting a fault includes,

[0136] Continuously monitor the voltage and current data of each segment;

[0137] The fault index is calculated based on the voltage and current data of each segment. The calculation formula is as follows:

[0138]

[0139] Where F is the fault indicator, V is the measured voltage, V n is the rated voltage, I is the measured current, I n is the rated current;

[0140] When the fault index F exceeds the fault threshold, it is judged as a fault;

[0141] Control the disconnectors at both ends of the faulty section to disconnect and isolate the faulty section from the system;

[0142] Adjust the parameters of other high-frequency transformers in normal sections to ensure stable operation of the system;

[0143] Furthermore, the fault threshold is determined by a dynamic adjustment method, and the specific steps are as follows:

[0144] Set the initial fault threshold F according to system characteristics t ;

[0145] Continuously collect system operation data;

[0146] Use the sliding window method to analyze the data of the last N time points;

[0147] Calculate the average value μ of the data in the sliding window F , standard deviation σ F , skewness S F And the kurtosis K F ;

[0148] The fault threshold is adjusted dynamically, and the adjustment formula is as follows:

[0149]

[0150] Among them, α 1 , β 1 , γ 1 is the adjustment coefficient, is the threshold before updating, is the updated threshold, σ F,ref is the reference standard deviation;

[0151] Regularly calculate the system's false alarm rate P false and the false negative rate P miss ;

[0152] Further fault threshold adjustment is performed based on the false alarm rate and missed alarm rate;

[0153] Every fixed time period t 0 , repeat the above steps to continuously optimize the fault threshold.

[0154] Furthermore, the present embodiment also provides a photovoltaic energy storage DC bus segmented high-frequency transformer access system, comprising: a photovoltaic array connection module, a data acquisition and adjustment module, a power distribution module, and a fault monitoring and isolation module;

[0155] The photovoltaic array connection module is used to connect the photovoltaic array and the energy storage unit to the DC busbar, segment the DC busbar, and connect each segment of the DC busbar to the power grid through a high-frequency transformer;

[0156] The data acquisition and adjustment module is used to collect the voltage and current data of each segment and the grid side, and adjust the transformation ratio and switching frequency of each high-frequency transformer according to the collected voltage and current data;

[0157] The power distribution module is used to collect photovoltaic energy storage operation data, and plan the operation mode of each segment according to the photovoltaic energy storage operation data, adjust the power distribution of each segment at different time periods, and adjust the charging and discharging power of the energy storage unit;

[0158] The fault monitoring and isolation module is used to monitor the operating status of the photovoltaic energy storage system and isolate the faulty segment when a fault is detected.

[0159] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 2As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a comprehensive evaluation method suitable for orderly access of large-scale distributed power sources is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse.

[0160] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the following steps are implemented: connecting a photovoltaic array and an energy storage unit to a DC bus, segmenting the DC bus, and connecting each segment of the DC bus to a power grid via a high-frequency transformer;

[0161] Collecting voltage and current data of each segment and the grid side, and adjusting the transformation ratio and switching frequency of each high-frequency transformer according to the voltage and current data;

[0162] Collecting photovoltaic energy storage operation data, planning the operation mode of each segment according to the photovoltaic energy storage operation data, adjusting the power allocation of each segment at different time periods, and adjusting the charging and discharging power of the energy storage unit;

[0163] Monitor the operating status of the photovoltaic energy storage system and isolate the faulty segment when a fault is detected.

[0164] Example 2

[0165] Reference Figure 1 - Figure 2 , which is the second embodiment of the present invention, and provides a photovoltaic energy storage DC bus segmented high-frequency transformer access method. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0166] This embodiment aims to verify the effectiveness and advantages of a method for connecting photovoltaic energy storage to DC busbars with segmented high-frequency transformers. The test system includes a photovoltaic array, an energy storage unit, a DC busbar, a high-frequency transformer, and a grid connection device. The test object is a photovoltaic power station with a total installed capacity of 500kW and an energy storage unit capacity of 200kWh. The test was conducted within a week, covering different meteorological conditions and load requirements.

[0167] System connection and segmentation: Connect the photovoltaic array and energy storage unit to the DC busbar, and divide the DC busbar into five electrically independent segments according to their distribution. Isolation switches are installed between the segments so that the faulty segment can be quickly isolated in the event of a fault.

[0168] High-frequency transformer access: Each section of the DC busbar is connected to the grid through a high-frequency transformer. The initial transformation ratio of each high-frequency transformer is set to 1:1, and the initial switching frequency is set to 50kHz.

[0169] Data collection and adjustment: The voltage and current data of each segmented DC busbar are collected through sensors. According to the collected data, the transformation ratio and switching frequency of each high-frequency transformer are adjusted in real time. The specific adjustment formula is as follows:

[0170] Operation mode planning: Collect system operation data, including real-time output power data of the photovoltaic array, real-time power consumption data of each load point, current charge state of the energy storage unit, and voltage and current parameters on the grid side. Based on these data, pre-plan the operation mode of each segment, including photovoltaic power generation sufficient mode, load peak mode, energy storage charging mode, energy storage discharging mode and grid balance mode.

[0171] Fault monitoring and isolation: Continuously monitor the voltage and current data of each segment and calculate the fault index. When the fault index exceeds the preset threshold, the isolation switches at both ends of the fault segment are controlled to disconnect, isolating the fault segment from the system, and adjusting the high-frequency transformer parameters of other normal segments to maintain system stability.

[0172] Table 1 Photovoltaic energy storage system operation data record table

[0173] Parameter name Segment 1 Segment 2 Segment 3 Segment 4 Segment 5 unit Voltage 400V 405V 410V 415V 420V V Current 50A 52A 48A 51A 49A A DC side power 20kW 21kW 19.7kW 21.2kW 20.6kW kW AC side power 19.5kW 20.3kW 19.2kW 20.8kW 20.2kW kW Switching frequency 50kHz 51kHz 49.5kHz 51.5kHz 50.5kHz kHz Energy storage unit charge state 80％ 78％ 82％ 79％ 81％ ％ Fault indicators 0.02 0.01 0.015 0.01 0.03 -

[0174] It can be seen from the test data that the photovoltaic energy storage DC bus segmented high-frequency transformer access method of the present invention has significant advantages and innovations in practical applications. First, through the access of segmented DC bus and high-frequency transformer, the efficient transmission and distribution of electric energy is effectively realized, the transmission loss is reduced, and the system energy efficiency is significantly improved. For example, the DC side power of segment 1 is 20kW, while the AC side power is 19.5kW, and the conversion efficiency is as high as 97.5%.

[0175] Secondly, the data acquisition and real-time adjustment mechanism ensures the stable operation of the system under different load and meteorological conditions. The switching frequencies of segment 2 and segment 4 are adjusted to 51kHz and 51.5kHz respectively, ensuring the smooth operation of the system under power fluctuations and avoiding drastic changes in voltage and current.

[0176] In addition, through the collection of system operation data and intelligent operation mode planning, the effective switching of photovoltaic power generation sufficient mode, load peak mode, energy storage charging mode, energy storage discharge mode and grid balance mode enables the system to be dynamically adjusted according to actual needs. For example, in the photovoltaic power generation sufficient mode of segment 3, the charge state of its energy storage unit reaches 82%, ensuring that the power can be released in time during the peak load period to meet the power demand.

[0177] Finally, the fault monitoring and isolation mechanism enhances the safety and reliability of the system. In the data, the fault index of segment 5 reached 0.03, exceeding the preset threshold. The system quickly isolated the faulty segment and adjusted the high-frequency transformer parameters of other segments to ensure the continuous and stable operation of the system. This mechanism effectively prevents the spread of faults, protects other normally operating segments, and improves the overall safety of the system.

[0178] Compared with the existing technology, the present invention has significant advantages in system energy efficiency, operation stability, intelligent management and safety. Through reasonable data collection, real-time adjustment and intelligent operation mode planning, the system shows excellent performance under different operating conditions, proving the innovation and practical value of the invention in practical applications.

[0179] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0180] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0181] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0182] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0183] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0184] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0185] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A photovoltaic energy storage DC bus segmented high-frequency transformer access method, characterized in that: include, Connecting the photovoltaic array and the energy storage unit to a DC busbar, segmenting the DC busbar, and connecting each segment of the DC busbar to a power grid via a high-frequency transformer; Collect the voltage and current data of each segment and the grid side, and adjust the transformation ratio and switching frequency of each high-frequency transformer according to the collected voltage and current data; Collecting photovoltaic energy storage operation data, and planning the operation mode of each segment according to the photovoltaic energy storage operation data, adjusting the power allocation of each segment at different time periods, and adjusting the charging and discharging power of the energy storage unit; Monitor the operating status of the photovoltaic energy storage system and isolate the faulty segment when a fault is detected; The segments include, According to the distribution of photovoltaic arrays and energy storage units, the DC busbar is divided into multiple electrically independent sections; isolating switches are set between the sections; The step of adjusting the transformation ratio and switching frequency of each high-frequency transformer includes: The power of each segment is calculated according to the voltage and current data, and the transformation ratio of the corresponding high-frequency transformer is adjusted according to the power of each segment and the grid-side voltage. The calculation formula is as follows: Where n is the transformation ratio, λ1 is the correction coefficient, P dc is the DC side power, P ac is the AC side power, V ac is the grid voltage, V dc is the DC bus voltage; According to the power fluctuation of each segment, adjust the switching frequency of the corresponding high-frequency transformer. The calculation formula is as follows: Among them, f is the adjusted switching frequency, f0 is the reference frequency, λ2 is the adjustment coefficient, ΔP is the power fluctuation, P rated is the rated power.

2. The photovoltaic energy storage DC bus segmented high-frequency transformer access method according to claim 1, characterized in that: The photovoltaic energy storage operation data includes the real-time output power data of the photovoltaic array, the real-time power consumption data of each load point and the current charge state of the energy storage unit; the operation modes of each segment are planned to include photovoltaic power generation sufficient mode, load peak mode, energy storage charging mode, energy storage discharging mode and grid balance mode.

3. The photovoltaic energy storage DC bus segmented high-frequency transformer access method according to claim 2, characterized in that: The adjusting the power allocation of each segment includes: During system operation, the power distribution of each segment is adjusted according to the operation mode of the current period. The calculation formula is as follows: Among them, P i is the allocated power of the ith segment, P total is the total power, w i is the weight factor of the i-th segment, S i is the capacity of the i-th segment, Σ(w j *S j ) is the sum of weighted capacities of all segments; The step of adjusting the charging and discharging power of the energy storage unit includes: Real-time monitoring of the charge state of the energy storage unit; According to the charge state of the energy storage unit and the system operation requirements, the charging and discharging of the energy storage unit is controlled. The calculation formula is as follows: P b =(SOC-SOC ref )·k+(P gen -P load )·β2 Among them, P b is the charging and discharging power of the energy storage unit, SOC is the current state of charge, SOC ref is the target state of charge, k is the proportionality coefficient, P gen is the power generation, P load is the load power, β2 is the balance coefficient.

4. The photovoltaic energy storage DC bus segmented high-frequency transformer access method according to claim 3, characterized in that: When a fault is detected, isolating the fault segment includes: Continuously monitor the voltage and current data of each segment; The fault index is calculated based on the voltage and current data of each segment. The calculation formula is as follows: Where F is the fault indicator, V is the measured voltage, V n is the rated voltage, I is the measured current, I n is the rated current; When the fault index F exceeds the fault threshold, it is judged as a fault; Control the disconnectors at both ends of the faulty section to disconnect and isolate the faulty section from the system; Adjust the parameters of high-frequency transformers in other normal sections to maintain system stability.

5. The photovoltaic energy storage DC bus segmented high-frequency transformer access method according to claim 4, characterized in that: The fault threshold is determined by a dynamic adjustment method, and the specific steps include: Set the initial fault threshold F according to system characteristics t ; Continuously collect system operation data; Use the sliding window method to analyze the data of the last N time points; Calculate the average value μ of the data in the sliding window F , standard deviation σ F , skewness S F And the kurtosis K F ; The fault threshold is adjusted dynamically, and the adjustment formula is as follows: Among them, α1, β1, and γ1 are adjustment coefficients. is the threshold before updating, is the updated threshold, σ F,ref is the reference standard deviation; Regularly calculate the system's false alarm rate P false and the false negative rate P miss ; And readjust the fault threshold according to the false alarm rate and missed alarm rate; The above steps are repeated every fixed time period t0.

6. A photovoltaic energy storage DC bus segmented high-frequency transformer access system, based on the photovoltaic energy storage DC bus segmented high-frequency transformer access method according to any one of claims 1 to 5, characterized in that: Including photovoltaic array connection module, data acquisition and adjustment module, power distribution module and fault monitoring and isolation module; The photovoltaic array connection module is used to connect the photovoltaic array and the energy storage unit to the DC busbar, segment the DC busbar, and connect each segment of the DC busbar to the power grid through a high-frequency transformer; The data acquisition and adjustment module is used to collect the voltage and current data of each segmented DC busbar, and adjust the transformation ratio and switching frequency of each high-frequency transformer according to the collected data; The power allocation module is used to collect system operation data, plan the operation mode of each segment according to the system operation data, adjust the power allocation of each segment at different time periods, and adjust the charging and discharging power of the energy storage unit; The fault monitoring and isolation module is used to monitor the operating status of the photovoltaic energy storage system and isolate the faulty section when a fault is detected.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the photovoltaic energy storage DC bus segmented high-frequency transformation access method according to any one of claims 1 to 5 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the photovoltaic energy storage DC bus segmented high-frequency transformation access method according to any one of claims 1 to 5 are implemented.

Images