Voltage quality monitoring and early warning method based on photovoltaic transformer area and fusion terminal

Abstract

The invention belongs to the technical field of power distribution automation, and discloses a voltage quality monitoring and early warning method based on a photovoltaic transformer area and a fusion terminal. A voltage quality monitoring and early warning system based on a distributed photovoltaic transformer area and a fusion terminal comprises a data acquisition micro-application module, a voltage quality monitoring and early warning micro-application module, a data center micro-application module and a communication management micro-application module. The voltage quality monitoring and early warning micro-application performs data processing and analysis on data acquired by the data acquisition micro-application, and firstly calculates voltage quality indexes, such as voltage fluctuation rate, harmonic distortion rate, voltage qualification rate, voltage out-of-limit time statistics and the like; according to a preset voltage quality threshold value and the voltage quality index obtained through calculation, whether the voltage quality of the transformer area power grid and the terminal equipment is abnormal or not is judged, and corresponding early warning information is generated; and finally, the information is pushed to a master station system and related operation and maintenance personnel through the micro-application, so that countermeasures can be taken in time.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of power distribution automation, and in particular to a voltage quality monitoring and early warning method based on photovoltaic areas and fusion terminals. Background Art

[0002] With the rapid development and widespread application of distributed photovoltaic power generation technology, its access rate in the power grid continues to rise, and its impact on the voltage quality of the substation grid is becoming increasingly prominent. Distributed photovoltaic power generation is characterized by significant intermittent and random characteristics. Its output level is affected by a variety of natural factors such as weather changes, light intensity, and cloud cover. This can easily lead to voltage fluctuations, voltage deviations, harmonic pollution, and three-phase imbalance in the substation grid. These voltage quality issues not only affect the normal operation of power equipment and shorten its service life, but can also lead to safety hazards such as increased power loss and malfunctioning relay protection. This in turn has a negative impact on the user's power quality experience, such as unstable operation of electrical equipment and increased measurement errors of precision instruments.

[0003] Traditional voltage quality monitoring methods primarily rely on the power grid company's centralized monitoring system. These systems typically monitor the entire power grid at a macro level, making it difficult to implement refined, real-time voltage quality monitoring and early warning for distributed photovoltaic access grids. Furthermore, traditional monitoring systems often focus on grid-side voltage quality indicators, such as substation outlet voltage and line voltage, while ignoring voltage quality issues at the end user end. With the rapid development of smart grid and IoT technologies, the digitalization and intelligence of power systems are constantly improving, making voltage quality monitoring of terminal equipment particularly important. Real-time monitoring and analysis of user-side voltage quality not only helps power grid companies better understand the impact of distributed photovoltaic access on the grid, but also provides users with personalized power quality optimization recommendations, improving user satisfaction.

[0004] Therefore, developing a voltage quality monitoring and early warning method based on distributed photovoltaic substations and integrated terminals has important practical significance and value. The promotion and application of this method will provide technical support for the large-scale grid connection of distributed photovoltaic power generation, assist in the construction of new power systems and the realization of energy transformation goals. Summary of the Invention

[0005] The purpose of the present invention is to provide a voltage quality monitoring and early warning method based on photovoltaic substations and integrated terminals. This method can monitor the voltage quality of the substation power grid and terminal equipment in real time, provide timely early warning of voltage anomalies, solve the problems faced by the substation power grid with distributed photovoltaic access in voltage quality management, ensure the stability of the power grid and power supply reliability, and provide decision support for power grid operation and maintenance personnel.

[0006] To achieve the above objectives, the present invention provides a voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals, comprising the following steps: Step 1: Use a voltage quality monitoring and early warning system based on distributed photovoltaic areas and integrated terminals. The system includes micro-application modules, including data acquisition micro-application module, voltage quality monitoring and early warning micro-application module, data center micro-application module, and communication management micro-application module; Step 2: Start the micro-application module and initialize it, loading the configuration and device profile information; Step 3: Connect to the interface of the data center micro-application module through the message bus and subscribe to the information reported by the data collection micro-application module; Step 4: If the delay time is met, the real-time voltage data of the fusion terminal is obtained, and the voltage quality monitoring and warning micro-application module is called to perform voltage quality calculation and analysis operations, calculate voltage quality related indicator data, generate relevant warning information, and report it to the message bus; Step 5: Loop and read the data of the Nth device. If the data is updated, proceed to step 4. If the data is not updated or the communication fails, report the communication failure information and continue to read the data of the next device.

[0007] Furthermore, the voltage quality monitoring and early warning micro-application module includes a voltage deviation judgment and analysis module, a voltage harmonic over-limit judgment and analysis module, a voltage fluctuation judgment and analysis module, and a voltage over-limit judgment and analysis module, which compares with the set threshold value to determine whether there is any abnormality in the voltage quality.

[0008] Furthermore, the method further includes step 6: after processing the data of all photovoltaic point devices in the distributed photovoltaic area, returning to step 4 and waiting for the next cycle.

[0009] Furthermore, in step 4, the warning information is reported to the message bus. Other modules subscribe to the data, the data center micro-application module saves the data, and the communication management micro-application module forwards the data to the master station system and power grid operation and maintenance personnel. The warning information includes: L0 normal means the voltage quality is within the normal range; L1 Caution means the voltage quality is close to the threshold and needs attention; The L2 alarm indicates that the voltage quality exceeds the threshold and immediate action is required.

[0010] Furthermore, in step 4, the voltage quality monitoring and early warning micro-application module is called to perform voltage quality calculation and analysis operations, including the following steps: S1: Calculate voltage quality related indicator data; S2: Determine whether the voltage deviation is greater than a set threshold. If so, enter the voltage deviation judgment and analysis module for data analysis; otherwise, enter step S3; S3: Determine whether the voltage harmonic distortion rate is greater than a set threshold. If so, enter the voltage harmonic over-limit analysis module for data analysis; otherwise, enter step S4. S4: Determine whether the voltage fluctuation rate is greater than a set threshold. If so, enter the voltage fluctuation analysis module for data analysis; otherwise, enter step S5; S5: Determine whether the voltage over-limit is greater than a set threshold. If so, enter the voltage over-limit analysis module for data analysis; otherwise, enter step S6; S6: Perform statistics on the voltage qualification rate and the time when the voltage exceeds the upper and lower limits, and save the daily and monthly voltage qualification rate curves and the statistical time when the voltage exceeds the upper and lower limits to the historical database.

[0011] Furthermore, step S1 calculates voltage quality related indicator data, including the following steps: T1: Calculate voltage deviation: Evaluate the relationship between actual voltage and nominal voltage. The formula for calculating voltage deviation is: ,in is the actual voltage calculated from the collected data, is the set nominal voltage; T2: Calculate the total harmonic distortion of the voltage signal to evaluate the quality of the voltage signal. The formula for calculating harmonic distortion is: ,in is the voltage fundamental value, is the effective value of harmonics; T3: Calculate the standard deviation of the voltage data to evaluate the discreteness of the voltage fluctuation. The formula for calculating the standard deviation is: ,in For each voltage reading, is the average value of the voltage, and N is the total number of readings.

[0012] Furthermore, the message bus in step 2 is MQTT.

[0013] Furthermore, the delay time in step 4 is a timing analysis interval, a variable input parameter, and the unit is minutes.

[0014] Beneficial effects: The present invention provides a voltage quality monitoring and early warning method based on photovoltaic substations and integrated terminals. Combining the characteristics of distributed photovoltaic power generation, the present invention realizes automated data processing and early warning generation through advanced algorithms, and realizes real-time monitoring and early warning of the voltage quality of the substation power grid and end users connected to distributed photovoltaic power stations, significantly improving the power supply quality of the power grid and the user's electricity experience; through refined and real-time voltage quality monitoring, it can timely discover and handle voltage anomalies and ensure the safe operation of power equipment; the timely output of early warning information and the communication function enable power grid operation and maintenance personnel to quickly respond to and handle voltage quality problems, further improving operation and maintenance efficiency. It solves the shortcomings of traditional monitoring systems in voltage quality monitoring of distributed photovoltaic access substation power grids, and provides a strong guarantee for the stable operation of the substation power grid and the electricity safety of end users. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a block diagram of a low-voltage photovoltaic area system according to an embodiment of the present invention; Figure 2 This is a general flow chart of a voltage quality monitoring and early warning method based on a photovoltaic area and a fusion terminal according to an embodiment of the present invention; Figure 3 This is a flowchart of the voltage quality calculation and analysis process involved in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The preferred structure and implementation method of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] like Figures 1 to 3 As shown, an embodiment of the present invention discloses a technical solution for a voltage quality monitoring and early warning method based on a photovoltaic area and a fusion terminal.

[0018] Example 1 Figure 1 This is a block diagram of the low-voltage photovoltaic substation system involved in an embodiment of the present invention. The smart distribution transformer combine terminal unit (SDTC) is an intelligent data collection and control terminal installed in a low-voltage substation. It meets the requirements of high-performance concurrency, large-capacity storage, multiple data collection objects, localized analysis and decision-making, and collaborative computing. It features data collection, equipment operating status monitoring, and energy metering, supporting marketing, power distribution, and emerging business development needs.

[0019] The system block diagram of the low-voltage photovoltaic area is as follows: Figure 1The system is mainly used to monitor the voltage quality of substations and photovoltaic installation points. The equipment included includes substation fusion terminals, photovoltaic inverters, photovoltaic switches, electricity meters, collectors, etc. The substation intelligent fusion terminal is installed on the low-voltage side of the substation transformer. The fusion terminal communicates with substation photovoltaic inverters, photovoltaic switches, multi-function meters and other equipment through communication methods such as HPLC / HRF and RS485. On the one hand, it sends data to the distribution automation master station to achieve observability and measurability of photovoltaic equipment. On the other hand, the fusion terminal uses edge computing to obtain voltage quality indicator data such as voltage deviation, harmonic distortion, and voltage fluctuation standard deviation of the substation and each photovoltaic point, generates early warning information based on the set threshold, and pushes it to the master station system and operation and maintenance personnel through the APP.

[0020] The voltage quality monitoring and early warning system based on distributed photovoltaic areas and integrated terminals in this embodiment mainly includes a data acquisition micro-application module, a voltage quality monitoring and early warning micro-application module, a data center micro-application module, and a communication management micro-application module.

[0021] The overall process of a voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals in this embodiment is as follows: Figure 2 As shown, the specific steps include: Step 1: Use a voltage quality monitoring and early warning system based on distributed photovoltaic areas and integrated terminals. The system includes micro-application modules, including data acquisition micro-application module, voltage quality monitoring and early warning micro-application module, data center micro-application module, and communication management micro-application module; Step 2: Start the micro-application module and initialize it, loading the configuration and device profile information; Step 3: Connect to the interface of the data center micro-application module through the message bus and subscribe to the information reported by the data collection micro-application module; Step 4: If the delay time is met, the real-time voltage data of the fusion terminal is obtained, and the voltage quality monitoring and warning micro-application module is called to perform voltage quality calculation and analysis operations, calculate voltage quality related indicator data, generate relevant warning information, and report it to the message bus; Step 5: Loop and read the data of the Nth device. If the data is updated, proceed to step 4. If the data is not updated or the communication fails, report the communication failure information and continue to read the data of the next device. Step 6: After processing the data of all photovoltaic point devices in the distributed photovoltaic area, return to step 4 and wait for the next cycle.

[0022] The communication management micro-application module in step 1 is responsible for integrating communication services between the terminal and the main station. The message bus in step 3 can refer to a messaging mechanism built using the MQTT protocol, enabling the sending and receiving of information between different components, modules, or applications. The delay time in step 4 is the timed analysis interval, a variable input parameter in minutes.

[0023] The data acquisition micro-application is responsible for collecting real-time voltage-related data from various nodes in the substation power grid and end users. The collection of real-time data can reach the minute level. Voltage-related data is mainly provided by photovoltaic inverters, smart switches and other devices. The devices communicate with the fusion terminal through HPLC / HRF or RS485 to HPLC / HRF communication methods. The data collected by the micro-application is stored in the terminal data center through the micro-application interface and reported to the bus for use by other micro-applications.

[0024] The voltage quality monitoring and early warning micro-application processes and analyzes the data collected by the data acquisition micro-application. First, it calculates voltage quality indicators, such as voltage fluctuation rate, harmonic distortion rate, voltage qualification rate, voltage over-limit time statistics, etc.; then, based on the preset voltage quality threshold and the calculated voltage quality indicators, it determines whether the voltage quality of the substation power grid and terminal equipment is abnormal, and generates corresponding early warning information; finally, it pushes the information to the main station system and relevant operation and maintenance personnel through the micro-application so that timely response measures can be taken.

[0025] The voltage quality monitoring and early warning micro-application module includes a voltage deviation judgment and analysis module, a harmonic over-limit judgment and analysis module, a voltage fluctuation judgment and analysis module, and a voltage over-limit judgment and analysis module. It mainly compares with the set threshold to determine whether there are any abnormalities in voltage quality. When the voltage quality indicator exceeds the preset threshold, the early warning judgment module generates corresponding early warning information and reports it to the message bus. Other modules subscribe to this data, such as the data center micro-application module, which saves the data, and the communication management micro-application module, which forwards the data to the master station system and power grid operation and maintenance personnel. The categories of early warning information include: L0 Normal: Voltage quality is within the normal range.

[0026] L1 Note: Voltage quality is approaching the threshold and requires attention.

[0027] L2 alarm: Voltage quality exceeds the threshold and immediate action is required.

[0028] The voltage quality calculation and analysis process involved in the embodiment of the present invention is as follows: Figure 3 , specifically including the following steps: (1) Calculate voltage quality related index data: Calculate voltage deviation: Evaluate the relationship between actual voltage and nominal voltage. Voltage deviation is an important indicator for judging voltage quality. The size of the deviation can be used to determine whether the voltage is within an acceptable range. Voltage deviation formula: ,in represents the actual voltage calculated from the acquired data, Indicates the set nominal voltage (e.g. 220V).

[0029] Calculate the total harmonic distortion (THD) of the voltage signal: This is used to evaluate the quality of the voltage signal. THD is used to measure the relative size of the harmonic components in the signal. Excessive harmonic distortion may cause equipment damage or performance degradation. Harmonic distortion calculation formula: ,in is the voltage fundamental value, is the effective value of harmonics.

[0030] Calculate the standard deviation of voltage data: This is used to evaluate the dispersion of voltage fluctuations. The standard deviation can provide useful information about voltage fluctuations, which is very important for the stability of the equipment. The standard deviation calculation formula is: ,in : Every voltage reading, : Average value of voltage, N: Total number of readings.

[0031] (2) Determine whether the voltage deviation is greater than the set threshold. If so, enter the voltage deviation judgment and analysis module for data analysis; otherwise, proceed to the next step.

[0032] (3) Determine whether the voltage harmonic distortion rate is greater than the set threshold. If so, enter the voltage harmonic over-limit analysis module for data analysis; otherwise, proceed to the next step.

[0033] (4) Determine whether the voltage fluctuation rate is greater than the set threshold. If so, enter the voltage fluctuation analysis module for data analysis; otherwise, proceed to the next step.

[0034] (5) Determine whether the voltage over-limit is greater than the set threshold. If so, enter the voltage over-limit analysis module for data analysis; otherwise, proceed to the next step.

[0035] (6) Carry out statistics on the voltage qualification rate and the time when the voltage exceeds the upper and lower limits, and save the daily and monthly voltage qualification rate curves and the statistical time when the voltage exceeds the upper and lower limits to the historical database.

[0036] Through the above algorithms, the voltage quality monitoring and early warning system can effectively implement real-time monitoring, data analysis, and early warning functions. The various modules in the system work together to achieve comprehensive monitoring and control of the voltage quality of distributed photovoltaic points.

[0037] The present invention provides a voltage quality monitoring and early warning method based on photovoltaic substations and integrated terminals. Through real-time monitoring, multi-level early warning and convenient and fast data push, it solves the shortcomings of traditional monitoring systems in monitoring the voltage quality of distributed photovoltaic access substation power grids, and provides strong guarantees for the stable operation of the substation power grid and the electricity safety of end users.

[0038] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals, characterized in that: The following steps are involved: Step 1: Using a voltage quality monitoring and early warning system based on distributed photovoltaic areas and integrated terminals, the system includes micro-application modules, including a data acquisition micro-application module, a voltage quality monitoring and early warning micro-application module, a data center micro-application module, and a communication management micro-application module; Step 2: Start the micro-application module and initialize it, loading the configuration and device profile information; Step 3: Connect to the interface of the data center micro-application module through the message bus and subscribe to the information reported by the data collection micro-application module; Step 4: If the delay time is met, the real-time voltage data of the fusion terminal is obtained, and the voltage quality monitoring and warning micro-application module is called to perform voltage quality calculation and analysis operations, calculate voltage quality related indicator data, generate relevant warning information, and report it to the message bus; Step 5: Loop and read the data of the Nth device. If the data is updated, proceed to step 4. If the data is not updated or the communication fails, report the communication failure information and continue to read the data of the next device.

2. The voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals according to claim 1 is characterized in that: The voltage quality monitoring and early warning micro-application module includes a voltage deviation judgment and analysis module, a voltage harmonic over-limit judgment and analysis module, a voltage fluctuation judgment and analysis module, and a voltage over-limit judgment and analysis module, which compares with the set threshold to determine whether there is any abnormality in the voltage quality.

3. The voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals according to claim 1 or 2 is characterized in that: The method further includes step 6: after processing the data of all photovoltaic point devices in the distributed photovoltaic area, returning to step 4 and waiting for the next cycle.

4. The voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals according to claim 1 or 2 is characterized in that: In step 4, the warning information is reported to the message bus. Other modules subscribe to the data. The data center micro-application module saves the data. The communication management micro-application module forwards the data to the master station system and power grid operation and maintenance personnel. The warning information includes: L0 normal means the voltage quality is within the normal range; L1 Caution means the voltage quality is close to the threshold and needs attention; The L2 alarm indicates that the voltage quality exceeds the threshold and immediate action is required.

5. The voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals according to claim 2 is characterized in that: In step 4, the voltage quality monitoring and early warning micro-application module is called to perform voltage quality calculation and analysis operations, including the following steps: S1: Calculate voltage quality related indicator data; S2: Determine whether the voltage deviation is greater than a set threshold. If so, enter the voltage deviation judgment and analysis module for data analysis; otherwise, enter step S3; S3: Determine whether the voltage harmonic distortion rate is greater than a set threshold. If so, enter the voltage harmonic over-limit analysis module for data analysis; otherwise, enter step S4. S4: Determine whether the voltage fluctuation rate is greater than a set threshold. If so, enter the voltage fluctuation analysis module for data analysis; otherwise, enter step S5; S5: Determine whether the voltage over-limit is greater than a set threshold. If so, enter the voltage over-limit analysis module for data analysis; otherwise, enter step S6; S6: Perform statistics on the voltage qualification rate and the time when the voltage exceeds the upper and lower limits, and save the daily and monthly voltage qualification rate curves and the statistical time when the voltage exceeds the upper and lower limits to the historical database.

6. The voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals according to claim 5 is characterized in that: Step S1 calculates voltage quality related index data, The following steps are involved: T1: Calculate voltage deviation: Evaluate the relationship between actual voltage and nominal voltage. The formula for calculating voltage deviation is: ,in is the actual voltage calculated from the collected data, is the set nominal voltage; T2: Calculate the total harmonic distortion of the voltage signal to evaluate the quality of the voltage signal. The formula for calculating harmonic distortion is: ,in is the voltage fundamental value, is the effective value of harmonics; T3: Calculate the standard deviation of the voltage data to evaluate the discreteness of the voltage fluctuation. The formula for calculating the standard deviation is: ,in For each voltage reading, is the average value of the voltage, and N is the total number of readings.

7. The voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals according to claim 1 is characterized in that: The message bus in step 2 is MQTT.

8. The voltage quality monitoring and early warning method based on photovoltaic areas and integrated terminals according to claim 1 is characterized in that: The delay time in step 4 is the timing analysis interval, a variable input parameter, and the unit is minutes.

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