Summary: With the continuous development of photovoltaic power generation, the demand for PV power generation monitoring systems is increasingly urgent. In the "Internet+" era, the concept of "Internet+" has become a driving force for technological production, promoting the upgrading and development of the industry. This article proposes an application technology for real-time data collection, analysis, and processing of operation data for decentralized photovoltaic power stations, enabling the viewing of real-time operational conditions and the monitoring and daily management of PV power station parameters through a mobile app.
Keywords: Internet + Photovoltaic Power Station; Remote OperationWe Platform; Data Collection; TCP Protocol; UDP Protocol
0. Preface
As photovoltaic power generation continues to evolve, the demand for PV power generation monitoring systems becomes increasingly urgent. In the "Internet+" era, the concept of "Internet+" has transformed into a driving force for technological production, promoting the upgrade and development of the industry. This article proposes an application technology for real-time data collection, analysis, and processing of operation data from decentralized PV power stations, allowing for the monitoring of real-time operation status, and the management of PV power station operation parameters through a mobile app.
1. System Design
1.1 Overall Design Concept
Solar panels convert sunlight into electricity after receiving sufficient light, which is then stored and converted into power by batteries. As night falls and light intensity decreases, the batteries begin to supply power to appliances, repeating the cycle. This conserves non-renewable resources and, with its simple wiring structure and easy operation, photovoltaic power generation is environmentally friendly and pollution-free, significantly reducing labor costs. The internet-based management system for photovoltaic power generation enables the networked unified management of decentralized photovoltaic power stations.
The system is operational, controlling the photovoltaic power station's data collection and control unit through data collection and transmission units. It monitors the operation and environmental parameters of on-site equipment in real-time, connects to the internet communication system via various network access methods, and sends the parameters to the backend server in real-time. The local monitoring and control system uses a photovoltaic power generation monitoring host to classify, summarize, analyze, and process the received data, generating charts for analysis. The mobile monitoring APP can synchronize with the monitoring host, display data, organize and analyze it, obtain operational parameters, view real-time operation, and manage the photovoltaic power station on a daily basis. This not only allows for real-time and mobile monitoring but also reduces operational costs and expenses. The overall structure is as shown in Figure 1, with specific functionalities including the photovoltaic power station data collection and control unit, data collection and transmission unit, network communication system, backend server, photovoltaic power generation monitoring host, and mobile APP.
1.2 Photovoltaic Power Plant Data Collection and Transmission Unit Hardware Design
The photovoltaic power station data collection, control, and transmission unit is primarily composed of temperature sensors, light sensors, humidity and temperature sensors, wind speed and direction sensors, digital potentiometers, electromagnetic relays, STM32F106 microcontrollers, network access modules, and circuit interface sections. The data collection and monitoring unit module transmits real-time temperature and humidity, light intensity, wind direction and speed, and power generation unit parameters to the back-end server via network communication. At the same time, the control and transmission unit receives various control commands from the monitoring host, enabling remote control of the power generation module's operation. The back-end server is responsible for data storage, monitoring system deployment, and connecting to the control end, establishing a link between the photovoltaic power station data collection unit and the monitoring system. The main functional modules of the back-end server are as shown in Figure 2.
1.3 Mobile Monitoring Platform Software System Design
The mobile monitoring APP is developed based on the Android system platform. The system communicates with the monitoring system of the background server through the TCP and UDP protocols. The APP can access the background server in real-time, monitor and control the operation of photovoltaic power stations, and provide convenient, quick, and real-time operations. The overall structure of the mobile APP client software is shown in Figure 3. The client software logs in to the remote server and transmits basic client parameters via the TCP protocol. After the basic operation parameters of the client are transmitted and processed, UDP protocol is used to synchronize the monitoring of the host parameters, display the data of the photovoltaic power generation module, obtain running parameters to view the real-time operation status, organize and analyze the data, and carry out daily management and monitoring of the photovoltaic power station.
2. System Testing Analysis and Conclusion
The Mobile Monitoring APP module is a sub-module of the background monitoring system in the photovoltaic power generation monitoring system research topic, providing a mobile monitoring platform for system administrators. The system's front-end data monitoring and collection module gathers data from various sensors on-site and transmits the collected results to the background server via the GPRS remote transmission module. The Mobile Monitoring APP can interact in real-time with the background server, displaying the operational status of designated power generation modules in real-time, and can send control commands to the monitoring modules as needed for on-site equipment control. After testing, the Mobile Monitoring APP module's parameters and the transmission and display of remote control have overall met the system design requirements. The next step will be to implement real-time multi-station monitoring and networking power generation scheduling control research based on the existing design.
3. AnkoRay Distributed Photovoltaic Operation and Maintenance Cloud Platform Introduction
3.1 Overview
AcrelCloud-1200 Distributed Photovoltaic Operation and Maintenance Cloud Platform monitors inverters, meteorological equipment, and camera devices at photovoltaic sites to assist users in managing their scattered PV sites. Key features include: site monitoring, inverter monitoring, power generation statistics, inverter one-line diagram, operation logs, alarm information, environmental monitoring, equipment records, operation and maintenance management, and role management. Users can access the platform via the WEB and APP to promptly grasp the efficiency and revenue of photovoltaic power generation.
3.2 Application Venue
Currently, China's two distributed application scenarios are residential rooftop photovoltaic systems in rural areas and commercial and industrial rooftop photovoltaics, both of which have seen rapid development this year.
3.3 System Structure
Inverters and multi-functional power metering instruments are installed in photovoltaic substation. Data collected is uploaded to the server through a gateway, where it is centrally stored and managed. Users can access the platform via PC to promptly obtain the operational status of the distributed photovoltaic power stations and the performance of each inverter. The overall structure of the platform is as shown in the figure.
3.4 System Features
The AcrelCloud-1200 Distributed Photovoltaic Operation and Maintenance Cloud Platform Software is based on the B/S architecture, allowing any authorized user to monitor the operation status of photovoltaic power stations across various buildings within the area through a WEB browser, based on their permission range. This includes information such as the geographical distribution of the power stations, station details, inverter status, power generation curve, grid connection status, current electricity generation, and total electricity generation.
3.4.1 Photovoltaic Power Generation
3.4.1.1 Comprehensive Dashboard
●Display the number, installed capacity, and real-time power generation of all photovoltaic power stations.
●Cumulative daily, monthly, and annual electricity generation and revenue.
Cumulative social benefits.
●Bar chart displays monthly electricity generation
3.4.1.2 Power Plant Status
● The Power Station Status displays basic parameters of the photovoltaic power station, including power generation capacity, subsidy electricity price, and peak power.
●Track daily, monthly, and annual power generation and revenue of photovoltaic power stations.
● The camera real-time monitors the on-site environment, integrating parameters such as illumination, temperature and humidity, and wind speed.
● Display the current number of photovoltaic power station inverters connected and their basic parameters.
3.4.1.3 Inverter Status
● Basic inverter parameters displayed.
● Display of daily, monthly, and annual electricity generation and revenue.
● Display inverter power and environmental irradiance curves through graphical charts.
● DC voltage and current query.
● Query for voltage, current, active power, frequency, and power factor.
Power Plant Generation Statistics
●Display statistics reports for the hourly, daily, monthly, and annual electricity generation of the selected power station.
3.4.1.5 Inverter Power Generation Statistics
● Display statistical reports for the time, date, month, and annual generation of the selected inverter
3.4.1.6 Power Distribution Diagram
● Real-time display of inverter's AC and DC side data.
● Display the current number of inverter interface components.
● Display current environmental parameters such as illuminance, temperature and humidity, wind speed, etc.
● Display inverter models and manufacturers.
3.4.1.7 Inverter Curve Analysis
● Display voltage, power, irradiance, and temperature curves on both AC and DC sides.
● Operation Log: User Login Status Inquiry.
● SMS Log: View SMS push time, content, sending results, and replies.
● Platform Operation Log: Check仪表 status, gateway offline conditions.
● Alarm Information: Categorize alarm divisions for graded processing, record alarm content, occurrence time, and confirmation status.
3.4.3 Operating Environment
●Video Surveillance: Real-time monitoring of the photovoltaic station's operation is possible through the installation of video cameras on-site. For cameras with hardware capabilities, recording playback and pan-tilt control functions are also supported.
3.5 System Hardware Configuration
The 220V grid-connected photovoltaic power generation systems are commonly used for residential rooftop PV installations, with an installed power of about 8kW.
Some small-scale photovoltaic power stations are designed for self-consumption, with excess electricity not feeding into the grid. Such photovoltaic power stations require the installation of anti-reverse current protection devices to prevent electricity from being sent back into the power grid. Given their smaller scale and dispersed nature, it is highly beneficial for the managers of these stations to utilize cloud platforms for their management. Ankorri's solutions for these photovoltaic power stations include the following aspects:
According to the National Grid's Q/GDW1480-2015 "Technical Regulations for Grid Connection of Distributed Power Sources," 8kW to 400kW systems can be connected to the grid at 380V. Photovoltaic power stations exceeding 400kW may also adopt multi-point 380V connections, subject to the approval of the local power department. Such distributed photovoltaic systems are mostly installed on industrial and commercial building rooftops, with self-generated power used on-site and excess power fed back into the grid. Before connecting to the distribution network, it is essential to clearly define the metering points, which should consider not only property boundaries but also the points where the distributed power sources exit and the users' self-use electrical lines meet. Each metering point should be equipped with a bidirectional electricity metering device, which must comply with the relevant provisions of DL/T448 and other standards and regulations. Smart electricity meters should be used, with technical specifications meeting the National Grid Corporation's standards for smart electricity meters. Distributed power source metering devices used for settlement and assessment should be equipped with collection equipment, connected to the electricity information collection system, to enable remote automatic collection of electricity usage information.
Photovoltaic arrays are connected to string inverters, or to inverters via a combiner box, and then connected to the enterprise's 380V power grid to achieve self-consumption with surplus electricity being fed into the grid. A metering electricity meter must be installed before the 380V connection point to measure the photovoltaic power generation. Additionally, a bidirectional metering electricity meter is required at the junction between the enterprise's power grid and the public grid to measure the electricity fed into the grid by the enterprise. The data should be uploaded to the power supply department's electricity information collection system for photovoltaic power generation subsidies and grid-connected electricity settlement.
Some photovoltaic power stations require monitoring the power quality at the grid connection points, including power frequency, magnitude of voltage, voltage unbalance, sudden voltage rise/fall/interruption, rapid voltage changes, harmonic/interharmonic THD, flicker, etc. A separate power quality monitoring device needs to be installed. Some photovoltaic power stations are self-generated and self-used, with excess electricity not feeding into the grid. This type of photovoltaic power station requires an anti-reverse current protection device to prevent power transmission to the grid. The system diagram is as follows.
This grid-connected PV power plant model features a moderate scale. Through the cloud platform, it utilizes data from PV generation and energy storage system operations. Ankorri's solutions for such PV power plants encompass the following aspects:
[Reference]
- Yin Wanghong, Jiang Jiaxin. Design and Implementation of a Mobile Monitoring Platform for Internet+ Photovoltaic Power Generation Monitoring System[J]. Journal of Education and Teaching, Issue 03, January (Lower), 2020.
- Shangdewei, Zhang Lihong, Ni Jiping. Embedded Low-Power Modem Based on Single-Chip Control[J]. Electronic Product World, 2003(01): 61-66.
- Ankorri Enterprise Microgrid Design and Application Handbook. 2022.05 Edition
