**Abstract:**
This paper presents a real-time temperature monitoring system for photovoltaic (PV) power generation equipment, developed using the LabVIEW platform. The system continuously tracks the temperature of PV modules, ambient conditions, combiner boxes, inverters, and transformers. By doing so, it ensures the safe and stable operation of the power plant while also providing critical data for predicting energy output. Additionally, the system monitors lightning protection bus boxes and grid-connected inverters, offering real-time insights into transformer temperatures, operational status, and fault information. This allows for better management of on-site equipment, ultimately reducing failure rates and improving overall system reliability.
**1. Introduction**
Photovoltaic power systems typically consist of PV modules, combiner boxes, inverters, and transformers. During operation, issues such as overheating due to equipment failures can occur, like transformer fan malfunctions leading to excessive heat. High operating temperatures can significantly reduce the lifespan and increase the failure rate of components, especially inverter internal devices like IGBTs. To address these challenges, real-time temperature monitoring is essential. It enables early detection of potential problems, allowing for timely preventive actions that enhance system safety, reliability, and efficiency.
Currently, many photovoltaic plants rely on manual inspections, which are time-consuming and less reliable. To overcome this, this paper introduces a LabVIEW-based temperature monitoring system designed to automate the process. The system offers several key features: real-time temperature tracking of critical components, alarm functions for over-temperature events, data storage and analysis, and an intuitive user interface. These features not only improve operational efficiency but also support long-term development and maintenance of photovoltaic systems.
**2. Monitoring System Hardware Architecture**
**2.1 System Hardware Structure**
The hardware setup includes outdoor temperature sensors, combiner boxes, inverters, transformer temperature control units, 485 hubs, and RS485-RS232 converters. Each component is equipped with temperature sensors to monitor internal and environmental conditions. For example, sensors in combiner boxes detect abnormal internal temperatures, while those in inverters and transformers track device and terminal temperatures. Communication is facilitated via RS485, chosen for its reliability, simplicity, and cost-effectiveness.
**2.2 RS485 Topology Design**
The RS485 communication topology includes hand-in-hand bus, star, and tree structures. While star topologies offer high speed, they are costly and complex. Tree topologies allow scalability but require repeaters. A hybrid approach combining the main bus structure with star segments was adopted to balance performance and cost. This design ensures stable communication across large photovoltaic sites, even when equipment is far from the control room.
**3. Monitoring System Software Design**
**3.1 Programming Environment**
LabVIEW, developed by National Instruments, is used for software implementation. Unlike traditional text-based languages, LabVIEW uses a graphical programming language (G), making it easier to develop and maintain. Its modular design, powerful data processing capabilities, and user-friendly interface make it ideal for real-time monitoring applications.
**3.2 Communication Protocol**
The system employs the standard RS485 ModBus RTU protocol with settings of 9600 baud, no parity, 8 data bits, and 1 stop bit. Data is validated using CRC checks, ensuring accurate communication between the host computer and field devices.
**3.3 System Software Implementation**
The software communicates with field devices through serial ports. It includes subroutines for serial communication and CRC validation, ensuring accurate data retrieval and processing. The program flow is structured to handle real-time data efficiently, enabling quick response to alarms and system events.
**4. Experiments and Debugging**
The system was deployed at the Shenzhou Power 5MW Photovoltaic Demonstration Station in Inner Mongolia. It monitored 172 combiner boxes, 28 inverters, and 5 transformers across five units. Field testing confirmed the system’s ability to display real-time temperatures, store data, generate reports, and trigger alarms. Operators verified the accuracy of readings using walkie-talkies and remote debuggers, while simulated faults tested the alarm functionality.
**5. Conclusion**
This paper describes a LabVIEW-based real-time temperature monitoring system for photovoltaic power plants. Designed with modularity and scalability in mind, the system improves operational efficiency, reduces manual workload, and enhances system reliability. Its application in large-scale installations demonstrates its value in supporting the growth and sustainability of the solar energy industry.
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