Grid-connected control system of photovoltaic power station

Abstract

The invention discloses a grid-connected control system of a photovoltaic power station, and the system carries out the data analysis and decision through the real-time monitoring of the voltage, current and temperature data of a battery array, and employs an intelligent algorithm. The system firstly calculates the overall voltage and the average voltage of a battery array and judges the state of a battery unit according to a preset threshold value, and for a low-voltage battery unit, the system realizes disconnection and replacement operation through a controller module to ensure the stability of the output voltage of a photovoltaic power station; meanwhile, the system also has an energy storage device management function, and can automatically start or release electric energy according to the total voltage of the battery array so as to supplement the power grid demand; in addition, the remote monitoring and communication module realizes real-time data monitoring and transmission of fault alarm information, and the flexibility and reliability of the system are improved. The system is suitable for photovoltaic power stations with different scales and requirements, can ensure that electric energy is efficiently and safely transmitted to a power grid, and provides powerful support for wide application of photovoltaic power generation.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power stations, in particular to a photovoltaic power station grid-connected control system, which can achieve the stability of the photovoltaic power station output voltage and improve the efficiency and reliability of photovoltaic power generation. Background Art

[0002] The photovoltaic power station grid-connected control system refers to a system installed in the photovoltaic power station, which automatically receives the active power and voltage (reactive) setting values ​​issued by the dispatching master station, automatically adjusts the active / reactive power of the inverter, SVC, SVG and other equipment in the station in a closed loop, and tracks the instructions issued by the dispatching master station in real time.

[0003] As the capacity of photovoltaic power stations increases, the system structure and control strategy of large photovoltaic power stations connected to the grid become more complex, and the requirements for grid-connected inverters also increase. The inverter is the core and key in the photovoltaic power generation grid-connected system. Reasonable design and improvement of the structure and control method of the inverter can effectively improve the system efficiency. At present, the inverter has developed from a single-stage topology to a multi-stage topology, and many topologies that combine the advantages of single-stage and multi-stage have also emerged.

[0004] In addition to the continuous advancement of inverter technology, the photovoltaic power station grid-connected control system also involves key technologies such as photovoltaic grid-connected inverter technology, photovoltaic grid-connected monitoring technology, anti-islanding protection technology, low voltage ride-through and DC grid-connected technology selection. The comprehensive application of these technologies ensures that the photovoltaic power station can be efficiently and stably connected to the grid.

[0005] Although the existing technology has made significant progress in the control of photovoltaic power station grid connection, the technology closest to this technical solution still has the following disadvantages:

[0006] 1. The inverter control strategy is not optimized enough:

[0007] Existing inverter control strategies may not be able to fully adapt to the complex working conditions when photovoltaic power stations are connected to the grid, resulting in low system efficiency or insufficient stability.

[0008] The inverter efficiency tends to decrease when the load factor is below 20% and above 80%, which limits the overall power generation efficiency of the photovoltaic power station.

[0009] 2. The reactive power compensation device responds slowly:

[0010] Although reactive power compensation devices such as SVC and SVG can effectively improve the stability of the power system, their response speed is relatively slow and they may not be able to cope with rapid changes in the power grid in a timely manner.

[0011] Traditional reactive power compensation devices such as synchronous phase condensers and shunt capacitors have limitations in response speed, loss noise, operation and maintenance, and have gradually been replaced by static reactive power compensation devices. However, the cost and technical requirements of the new devices are also relatively high.

[0012] 3. System integration and intelligence level need to be improved:

[0013] The existing photovoltaic power station grid-connected control system still needs to be improved in terms of system integration and intelligence level. For example, the system may not be able to realize functions such as remote monitoring and intelligent operation and maintenance, resulting in low operation and maintenance efficiency and low power generation benefits.

[0014] The configuration of the reactive power compensation device of a photovoltaic power station needs to be determined after calculating the reactive voltage based on the actual situation. This process may be cumbersome and not intelligent enough.

[0015] 4. Impact on grid stability:

[0016] The volatility and randomness of photovoltaic power generation may affect the stability of the power grid. For example, when the output power of a photovoltaic power station changes suddenly, it may cause problems such as grid voltage fluctuations or frequency deviations.

[0017] The entry of distributed photovoltaic power into the distribution network may also have an impact on relay protection, increasing the risk of grid operation.

[0018] In summary, the existing photovoltaic power station grid-connected control system still has deficiencies in terms of inverter control strategy, reactive power compensation device response speed, system integration and intelligence level, and impact on grid stability. Therefore, it is necessary to develop a more advanced, efficient and stable photovoltaic power station grid-connected control system to overcome these drawbacks. Summary of the invention

[0019] The object of the present invention is to provide a photovoltaic power station grid-connected control system, which includes a battery array, a data acquisition module, a central processing unit, a controller and other modules, and can achieve stable control of the output voltage of the photovoltaic power station.

[0020] To achieve the above object, the present invention provides the following technical solutions:

[0021] A photovoltaic power station grid-connected control system, the system comprising:

[0022] a) Battery array module, which consists of multiple photovoltaic cell units connected in series or in parallel, converting solar energy into electrical energy;

[0023] b) A data acquisition module, connected to the battery array module, to collect the voltage V of each battery cell or battery group in the battery array in real time i 、Current I i data, and optionally temperature Ti data;

[0024] c) a central processing unit module, which is in communication with the data acquisition module and receives and analyzes the data transmitted by the data acquisition module;

[0025] d) a controller module, connected to the central processing unit module and the battery array module, and performing the following operations according to instructions of the central processing unit module;

[0026] e) The output circuit module is connected to the power grid and transmits the adjusted stable electric energy to the power grid.

[0027] Furthermore, in the CPU module, the overall voltage V of the battery array is calculated according to the following formula: total and the average voltage V avg :

[0028]

[0029] Where n is the number of battery cells or battery packs; and V is determined according to a preset algorithm. avg Is it lower than the first preset threshold V th1 , and identify V i Below the second preset threshold V th2 Low voltage battery cell or battery pack.

[0030] Furthermore, the control module performs the following operations:

[0031] Disconnect V i is lower than the second preset threshold V th2 The connection of low-voltage battery cells or battery packs to the output circuit, while selecting and connecting the same number or V i Higher than the third preset threshold V th3 The high-voltage battery unit or battery group is connected to the output circuit to maintain the stability of the output voltage of the photovoltaic power station.

[0032] Furthermore, the data acquisition module also includes a temperature sensor for monitoring the operating temperature T of the battery array module. i , and transmit the temperature data to the central processing unit module; the central processing unit module also calculates the average temperature T of the battery array according to the following formula avg :

[0033]

[0034] And according to the average temperature T avg Adjust the first preset threshold V th1 , the second preset threshold V th2 or the third preset threshold V th3, to compensate for the impact of temperature changes on battery performance.

[0035] Furthermore, the central processing unit module is also configured with a fault diagnosis algorithm for analyzing the data transmitted by the data acquisition module and determining the fault according to the voltage deviation ΔV i and / or current deviation ΔI i Identify abnormal battery cells or battery groups in the battery array and send instructions to the controller module to isolate the faulty cells to ensure the continuous and stable operation of the system.

[0036] Furthermore, the controller module also includes one or more relays or switch devices.

[0037] Furthermore, the system also includes a communication module for data transmission between the central processing unit module and the remote monitoring center, including real-time voltage, current, temperature data, and fault alarm information.

[0038] Furthermore, the system further includes an energy storage device for storing electrical energy when the battery array generates excess electrical energy, and releasing electrical energy when grid demand increases or the battery array output is insufficient, so as to improve the flexibility of the system and the stability of the grid.

[0039] Furthermore, the system adopts a modular design, and each module is connected through a standard interface, which facilitates the upgrade, maintenance and expansion of the system.

[0040] Beneficial effects of the present invention:

[0041] 1. Improve the accuracy and stability of power control: This technical solution can achieve accurate control of active power and reactive power of photovoltaic power stations by adopting advanced control algorithms and strategies, and improve the safety and stability of power grid operation;

[0042] 2. Enhance the ability to cope with the volatility and randomness of photovoltaic power plants: This technical solution can better cope with the volatility and randomness of photovoltaic power plants and reduce the impact and influence on the power grid by optimizing the structure and function of the control system;

[0043] 3. Improve equipment compatibility and communication reliability: This technical solution optimizes equipment selection and communication protocols, improves equipment compatibility and communication reliability, and ensures accurate data transmission and stable system operation;

[0044] 4. Strengthen data security: This technical solution adopts advanced data encryption and security protection technology to ensure the security of grid-connected control system data and prevent data leakage and illegal access.

[0045] In summary, the photovoltaic power station grid-connected control system proposed in this technical solution has significant technical advantages and beneficial effects, can promote the further development of photovoltaic power generation technology, and improve the safety and stability of power grid operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A system structure diagram of a grid-connected control system for a photovoltaic power station according to the present invention;

[0047] Figure 2 The present invention is a system implementation flow chart of a photovoltaic power station grid-connected control system. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0049] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The present invention proposes a photovoltaic power station grid-connected control system, which monitors the voltage, current and temperature data of the battery array in real time and uses intelligent algorithms to perform data analysis and decision-making to ensure the stability of the photovoltaic power station output voltage and efficiently and safely transmit electric energy to the power grid.

[0051] 1. System composition

[0052] Battery array module: It consists of multiple photovoltaic cells connected in series or in parallel, and is responsible for converting solar energy into electrical energy;

[0053] Data acquisition module: including voltage sensor, current sensor and temperature sensor, used to collect the voltage V of each battery cell or battery pack in the battery array in real time i 、Current I i and temperature T i data;

[0054] Central Processing Unit Module: Responsible for receiving and analyzing the data transmitted by the data acquisition module, executing algorithm calculations, and sending instructions to the controller module based on the calculation results;

[0055] Controller module: includes relays or switch devices, which are used to connect and disconnect battery cells or battery packs according to the instructions of the central processing unit module.

[0056] Output circuit module: connected to the power grid, used to transmit the adjusted stable electric energy to the power grid;

[0057] Communication module: used to realize data transmission between the central processing unit module and the remote monitoring center;

[0058] Energy storage device: used to store electrical energy when there is excess electricity generated by the battery array and release it when needed.

[0059] 2. Implementation process

[0060] 1. Data collection and preprocessing

[0061] The data acquisition module collects the voltage V of each battery cell or battery pack in the battery array in real time. i 、Current I i and temperature T i data;

[0062] The collected data is transferred to the central processing unit module for preprocessing, including data cleaning and outlier detection.

[0063] 2. Algorithm calculation and decision making

[0064] The CPU module calculates the overall voltage V of the battery array according to the following formula: total and the average voltage V avg :

[0065]

[0066] Judge V avg Is it lower than the first preset threshold V th1 , and identify V i Below the second preset threshold V th2 Low voltage battery cell or battery pack.

[0067] According to the average temperature T avg Adjust the first preset threshold V th1 , the second preset threshold V th2 or the third preset threshold V th3 (V th3 ≥V th2 ) to compensate for the impact of temperature changes on battery performance.

[0068] Optionally, a fault diagnosis algorithm is executed to analyze the voltage deviation ΔV i (ΔV i =|V i -V avg |) and / or current deviation ΔI i (ΔI i =|I i -I avg |), identify abnormal battery cells or battery packs,

[0069] Specifically,

[0070] (1) Structure of fault diagnosis algorithm

[0071] Data acquisition module:

[0072] Responsible for real-time acquisition of the voltage V of each battery cell or battery pack in the battery array i and current I i data;

[0073] The collected data is transmitted to the data processing module for further analysis.

[0074] Data processing module:

[0075] Receive voltage and current data transmitted by the data acquisition module;

[0076] Preprocess the data, including data cleaning and outlier detection, to ensure the accuracy and reliability of the data;

[0077] Calculate the voltage deviation ΔV i and current deviation ΔI i , that is, the difference between the voltage and current of each battery cell or battery pack and the normal value.

[0078] Fault diagnosis module:

[0079] The voltage deviation ΔV transmitted by the receiving data processing module i and current deviation ΔI i data;

[0080] Apply fault diagnosis algorithms to analyze voltage and current deviations to identify abnormal battery cells or battery packs;

[0081] Output fault diagnosis results, including the number of abnormal battery cells or battery packs, fault type (such as low voltage, abnormal current, etc.) and possible fault causes.

[0082] Control instruction generation module (optional):

[0083] Generate corresponding control instructions according to the fault diagnosis results output by the fault diagnosis module;

[0084] The control instructions are transmitted to the controller module to realize operations such as disconnection and replacement of abnormal battery cells or battery packs.

[0085] (2) Implementation of fault diagnosis algorithm

[0086] Determine the fault diagnosis threshold:

[0087] According to the actual situation of the photovoltaic power station and the performance parameters of the battery unit or battery group, set reasonable voltage deviation threshold and current deviation threshold;

[0088] When the voltage deviation ΔV i Or current deviation ΔI i When the set threshold is exceeded, the battery cell or battery pack is considered to be faulty.

[0089] Apply the fault diagnosis algorithm:

[0090] Commonly used fault diagnosis algorithms include fault diagnosis based on neural networks, fault diagnosis based on expert systems, etc.

[0091] In this example, a fault diagnosis algorithm based on BP neural network can be used to identify the mapping relationship between voltage deviation and current deviation and fault type by training the neural network model;

[0092] The collected voltage deviation ΔV i and current deviation ΔI i The data is input into the trained neural network model to obtain the fault diagnosis results.

[0093] Fault location and diagnosis:

[0094] According to the fault diagnosis results, determine the number and fault type of the abnormal battery unit or battery pack;

[0095] Based on the actual situation of the photovoltaic power station and the performance parameters of the battery unit or battery pack, analyze the possible causes of the failure, such as battery aging, poor connection, etc.

[0096] Troubleshooting:

[0097] Take appropriate troubleshooting measures based on the fault diagnosis results and possible fault causes;

[0098] For example, disconnect the abnormal battery cell or battery pack from the output circuit to prevent the fault from spreading; replace the faulty battery cell or battery pack to restore normal operation of the system.

[0099] Records and feedback:

[0100] Record relevant information of fault diagnosis and handling process, including fault time, fault type, fault cause, handling measures, etc.;

[0101] The fault information is fed back to the operation and maintenance personnel and managers of the photovoltaic power station so that they can understand the operating status of the system in a timely manner and take further maintenance measures.

[0102] 3. Control instruction generation and execution

[0103] The central processing unit module generates control instructions based on the algorithm calculation results, including disconnecting the low-voltage battery unit or battery pack from the output circuit, and selecting and connecting the high-voltage battery unit or battery pack to the output circuit;

[0104] The controller module receives control instructions and implements the connection and disconnection operations of the battery unit or battery pack through relays or switch devices.

[0105] 4. Power output and monitoring

[0106] The output circuit module transmits the adjusted stable electric energy to the power grid;

[0107] Real-time monitoring of voltage, current and other parameters on the grid side to ensure the stability and safety of the grid connection process.

[0108] 5. Remote monitoring and communication

[0109] Transmit real-time data, fault alarm information, etc. to the remote monitoring center through the communication module;

[0110] The remote monitoring center can monitor the operating status of the photovoltaic power station in real time and remotely adjust the control strategy or preset thresholds as needed.

[0111] 6. Energy storage device management

[0112] When the battery array generates excess electricity, the energy storage device activates and stores the electricity;

[0113] When grid demand increases or battery array output is insufficient, the energy storage device releases electrical energy to supplement grid demand.

[0114] This implementation process describes a method for constructing and operating a grid-connected control system for a photovoltaic power station. By real-time monitoring and analyzing the voltage, current and temperature data of the battery array, intelligent algorithms are used for decision-making and control to ensure the stability of the photovoltaic power station output voltage and the safety of the grid-connected process. The system is highly flexible and scalable, and can meet the grid-connected control requirements of photovoltaic power stations of different sizes and needs.

[0115] Specific application examples:

[0116] This example shows the construction and operation of a 1MW photovoltaic power station grid-connected control system. The system monitors the voltage, current and temperature data of the battery array in real time and uses intelligent algorithms for data analysis and decision-making to ensure the stability of the photovoltaic power station output voltage and efficiently and safely transmit electrical energy to the grid.

[0117] 1. System parameters and preset thresholds

[0118] 1. Battery array module:

[0119] Number of photovoltaic cells: n = 1000 (assuming each cell has a capacity of 1kW)

[0120] Single battery cell voltage V c : 30V

[0121] Single battery cell current I c :5A

[0122] 2. Preset threshold:

[0123] The first preset threshold V th1 : 28000V (considering system efficiency and safety margin, set to 93.3% of the total capacity of the battery array)

[0124] The second preset threshold V th2 : 25V (Battery cells below this value are considered low voltage)

[0125] The third preset threshold V th3 : 32V (Battery cells with a value higher than this are considered high voltage and can be used to replace low voltage battery cells)

[0126] Temperature compensation coefficient: According to the temperature change, for every 1℃ increase, V th1 、V th2 and V th3 Reducing by 0.1%, 0.2% and 0.1% respectively

[0127] 3. Other parameters:

[0128] System efficiency η: 90% (considering losses in battery array, inverter, line, etc.)

[0129] Energy storage device startup voltage threshold V_storage_threshold: 30000V (when the total voltage of the battery array exceeds this value, the energy storage device starts)

[0130] Energy storage device releases electric energy voltage threshold V_release_threshold: 27000V (when the total voltage of the battery array is lower than this value, the energy storage device releases electric energy)

[0131] 2. Implementation process and specific operations

[0132] 1. Data collection and preprocessing:

[0133] The data acquisition module collects the voltage V of each battery cell in real time i 、Current I i and temperature T i data;

[0134] The collected data is transferred to the central processing unit module for preprocessing, including data cleaning, outlier detection, etc.

[0135] Specifically:

[0136] (1) Data Collection

[0137] Voltage V i Collection of:

[0138] Each battery cell is equipped with a voltage sensor for real-time monitoring of the voltage of the battery cell;

[0139] The voltage sensor converts the collected voltage signal into a digital signal for subsequent processing;

[0140] The collected voltage data is transmitted to the data acquisition module via a data line or wirelessly.

[0141] Current I i Collection of:

[0142] Similar to voltage acquisition, each battery cell is also equipped with a current sensor;

[0143] The current sensor monitors the current output of the battery cell and converts it into a digital signal;

[0144] The current data is also transmitted to the data acquisition module via a data line or wirelessly.

[0145] Temperature T i Collection of:

[0146] The temperature sensor is installed near or inside the battery cell to monitor the temperature of the battery cell;

[0147] The temperature sensor converts the collected temperature data into a digital signal;

[0148] The temperature data is transmitted to the data acquisition module via a data line or wirelessly.

[0149] (2) Data preprocessing

[0150] Data cleaning:

[0151] Data cleaning refers to checking and correcting the collected data to eliminate or reduce errors;

[0152] During the data cleaning process, the CPU module checks the integrity of the data to ensure that there are no missing or duplicate values;

[0153] At the same time, the CPU module also smoothes the data to eliminate noise and fluctuations.

[0154] Outlier Detection:

[0155] Outliers are data points that differ significantly from the majority of data points and may be caused by sensor failure, data transmission errors, or battery cell failure.

[0156] The CPU module uses statistical methods (such as mean, standard deviation, median, etc.) to detect outliers;

[0157] Once an outlier is detected, the central processing unit module will mark or remove it to avoid negative impact on subsequent algorithm calculations and decisions.

[0158] Data calibration:

[0159] In some cases, sensors may have errors due to aging, drift, or environmental factors (such as temperature, humidity, etc.);

[0160] The CPU module will use a calibration algorithm to calibrate the collected data to eliminate or reduce these errors;

[0161] Calibration algorithms may include linear calibration, nonlinear calibration, or model-based calibration.

[0162] Data format conversion and storage:

[0163] The CPU module converts the preprocessed data into a format suitable for subsequent algorithm calculations and decision-making;

[0164] At the same time, the CPU module will also store the pre-processed data in a local or remote database for subsequent analysis and use;

[0165] Through the above data collection and preprocessing process, the photovoltaic power station grid-connected control system can obtain accurate and reliable battery unit voltage, current and temperature data, providing strong support for subsequent algorithm calculation and decision-making.

[0166] 2. Algorithm calculation and decision-making:

[0167] The CPU module calculates the overall voltage V of the battery array total and the average voltage V avg :

[0168]

[0169] (Assuming all battery cells have a voltage of 30V)

[0170]

[0171] Judge V avg (30V) is not lower than the first preset threshold V th1 (28000V / system efficiency 90% = approximate value of 30989V, but here to simplify the calculation, 30V and 28000V are directly compared / the influence of system efficiency is not considered. In fact, 30V should be compared with the threshold adjusted by system efficiency). Since the voltages of all battery cells are normal in this example, the battery cell replacement operation is not performed.

[0172] Monitor temperature data and adjust the preset threshold according to the temperature compensation coefficient; assuming the current temperature is 25°C, there is no need to adjust the preset threshold.

[0173] 3. Control instruction generation and execution:

[0174] In this case, since all battery cell voltages are normal, the CPU module does not generate control instructions;

[0175] If a low-voltage battery cell appears, the central processing unit module will generate a control instruction to disconnect the battery cell from the output circuit and select a high-voltage battery cell for replacement.

[0176] 4. Power output and monitoring:

[0177] The output circuit module transmits the adjusted stable electric energy to the power grid;

[0178] Real-time monitoring of the voltage, current and other parameters on the grid side to ensure the stability and safety of the grid connection process;

[0179] Specifically,

[0180] (1) Power output

[0181] Output circuit module design:

[0182] The output circuit module is the interface between the photovoltaic power station and the power grid, responsible for converting the electricity generated by the battery array into a form suitable for grid access;

[0183] This module usually contains key components such as inverters, filters, and transformers, which are used to convert DC power into AC power and adjust parameters such as voltage and frequency to meet grid requirements;

[0184] In this example, since the capacity of the photovoltaic power station is 1MW, the output circuit module must have corresponding power processing capabilities and ensure power conversion efficiency.

[0185] Power quality assurance:

[0186] The output circuit module uses precise inverter control and filtering technology to ensure that the output AC waveform is smooth, stable, and has low harmonic content;

[0187] The inverter uses advanced control algorithms such as PWM (Pulse Width Modulation) or SPWM (Sinusoidal Pulse Width Modulation) to optimize power quality;

[0188] The transformer is used to adjust the voltage level to ensure that the output voltage matches the grid voltage.

[0189] Grid-connected control:

[0190] The output circuit module has the function of grid-connected control and can monitor the grid status in real time, such as voltage, frequency, phase, etc.

[0191] When the grid is stable and meets the grid connection conditions, the output circuit module automatically transmits electric energy to the grid;

[0192] If the power grid fails or experiences an abnormality, such as voltage fluctuation or frequency deviation, the output circuit module can respond quickly and disconnect from the grid to protect the power station equipment and the grid.

[0193] (2) Real-time monitoring

[0194] Grid-side parameter monitoring:

[0195] Real-time monitoring of key parameters such as voltage, current, frequency, phase, etc. on the grid side;

[0196] Use high-precision sensors and measuring instruments to ensure the accuracy and reliability of monitoring data;

[0197] The monitoring data is transmitted to the central processing unit module or remote monitoring center in real time for further analysis and processing.

[0198] Fault warning and protection:

[0199] Analyze the power grid status in real time based on monitoring data and promptly detect potential faults or anomalies;

[0200] When the grid-side parameters exceed the preset range, the system can automatically trigger the fault warning mechanism and send an alarm to the operator;

[0201] If the fault is serious or endangers the safety of the power grid, the system can quickly cut off the connection with the power grid to prevent the fault from expanding.

[0202] Data recording and analysis:

[0203] Record monitoring data in real time and store it in a database for long-term data analysis and trend prediction;

[0204] Through data analysis, the operating efficiency, stability and grid-connected performance of the power station can be evaluated;

[0205] Based on the analysis results, the power plant's operating strategy can be adjusted or the control algorithm can be optimized to improve the overall performance of the power plant.

[0206] 5. Energy storage device management:

[0207] In this example, the total voltage of the battery array is 30000V, which does not reach the energy storage device startup voltage threshold V_storage_threshold (30000V), so the energy storage device does not start.

[0208] If the total voltage of the battery array exceeds V_storage_threshold, the energy storage device starts and stores electrical energy; if it is lower than V_release_threshold, the energy storage device releases electrical energy to supplement the grid demand.

[0209] 6. Remote monitoring and communication (optional):

[0210] Transmit real-time data, fault alarm information, etc. to the remote monitoring center through the communication module;

[0211] The remote monitoring center can monitor the operating status of the photovoltaic power station in real time and remotely adjust the control strategy or preset thresholds as needed;

[0212] Specifically:

[0213] (1) Real-time data collection and transmission

[0214] The communication module at the photovoltaic power station collects various data of the power station in real time through the sensor network, including the voltage, current, temperature of the battery array, and the operating status of key equipment such as inverters and energy storage devices;

[0215] After preliminary processing, the collected data is transmitted to the remote monitoring center in real time through the communication network (such as 4G / 5G, Wi-Fi, wired network, etc.).

[0216] (2) Fault alarm and early warning

[0217] When a power station fails or experiences an abnormal situation, the communication module will immediately generate fault alarm information and send it to the remote monitoring center through the communication network;

[0218] After receiving the alarm information, the remote monitoring center will immediately sound an audible and visual alarm and display the fault location and possible causes so that the operation and maintenance personnel can respond quickly.

[0219] (3) Remote monitoring and display

[0220] The remote monitoring center can display the operation status of the power station in real time through professional monitoring software, including the voltage distribution, current waveform, temperature distribution, etc. of the battery array;

[0221] The monitoring software also provides a historical data query function, which allows operation and maintenance personnel to view the operating data of the power station over a period of time in order to conduct data analysis and troubleshooting.

[0222] (4) Remote adjustment and control

[0223] The remote monitoring center can not only view the operation status of the power plant in real time, but also remotely adjust the control strategy or preset threshold of the power plant as needed;

[0224] For example, when the ambient temperature rises, the remote monitoring center can automatically or manually adjust the voltage threshold of the battery array to ensure the safe operation of the power station.

[0225] For example, when the output power of a power station fluctuates greatly, the remote monitoring center can adjust the control parameters of the inverter to stabilize the output power.

[0226] (5) Data analysis and reporting

[0227] The remote monitoring center can also conduct in-depth analysis of the power station's operating data and generate various operating reports and statistical analysis charts;

[0228] These reports and charts can help operation and maintenance personnel understand the operating efficiency, fault distribution and trends of the power plant, providing a scientific basis for the optimization and maintenance of the power plant.

[0229] In summary,

[0230] This example describes the specific application process of a 1MW photovoltaic power station grid-connected control system. By real-time monitoring and analysis of the voltage, current and temperature data of the battery array, and using intelligent algorithms for decision-making and control, the stability of the photovoltaic power station output voltage and the safety of the grid-connected process are ensured. At the same time, the system also has functions such as energy storage device management, remote monitoring and communication, which improves the flexibility and reliability of the system.

[0231] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A photovoltaic power station grid-connected control system, characterized in that: The system includes: a) Battery array module, which consists of multiple photovoltaic cell units connected in series or in parallel, converting solar energy into electrical energy; b) A data acquisition module, connected to the battery array module, to collect the voltage V of each battery cell or battery group in the battery array in real time i 、Current I i data, and optionally temperature T i data; c) a central processing unit module, which is in communication with the data acquisition module and receives and analyzes the data transmitted by the data acquisition module; d) a controller module, connected to the central processing unit module and the battery array module, and performing the following operations according to instructions of the central processing unit module; e) The output circuit module is connected to the power grid and transmits the adjusted stable electric energy to the power grid.

2. A photovoltaic power station grid-connected control system according to claim 1, characterized in that: In the CPU module, the overall voltage V of the battery array is calculated according to the following formula: total and the average voltage V avg : Where n is the number of battery cells or battery packs; and V is determined according to a preset algorithm. avg Is it lower than the first preset threshold V th1 , and identify V i Below the second preset threshold V th2 Low voltage battery cell or battery pack.

3. A photovoltaic power station grid-connected control system according to claim 2, characterized in that: The control module performs the following operations: Disconnect V i is lower than the second preset threshold V th2 The connection of low-voltage battery cells or battery packs to the output circuit, while selecting and connecting the same number or V i Higher than the third preset threshold V th3 The high-voltage battery unit or battery group is connected to the output circuit to maintain the stability of the output voltage of the photovoltaic power station.

4. A photovoltaic power station grid-connected control system according to claim 3, characterized in that: The data acquisition module also includes a temperature sensor for monitoring the operating temperature T of the battery array module. i , and transmit the temperature data to the central processing unit module; the central processing unit module also calculates the average temperature T of the battery array according to the following formula avg : And according to the average temperature T avg Adjust the first preset threshold V th1 , the second preset threshold V th2 or the third preset threshold V th3 , to compensate for the impact of temperature changes on battery performance.

5. A photovoltaic power station grid-connected control system according to claim 1, characterized in that: The central processing unit module is also equipped with a fault diagnosis algorithm for analyzing the data transmitted by the data acquisition module and i and / or current deviation ΔI i Identify abnormal battery cells or battery groups in the battery array and send instructions to the controller module to isolate the faulty cells to ensure continuous and stable operation of the system.

6. A photovoltaic power station grid-connected control system according to claim 1, characterized in that: The controller module also includes one or more relays or switching devices.

7. A photovoltaic power station grid-connected control system according to claim 1, characterized in that: The system also includes a communication module for data transmission between the central processing unit module and the remote monitoring center, including real-time voltage, current, temperature data, and fault alarm information.

8. A photovoltaic power station grid-connected control system according to claim 1, characterized in that: The system further includes an energy storage device for storing electrical energy when the battery array generates excess electrical energy and releasing electrical energy when grid demand increases or the battery array output is insufficient, so as to improve the flexibility of the system and the stability of the grid.

9. A photovoltaic power station grid-connected control system according to any one of claims 1 to 8, characterized in that: The system adopts a modular design, and each module is connected through a standard interface, which is convenient for system upgrade, maintenance and expansion.

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