Global political and economic initiatives are driving the demand for alternative power sources. With significant economic powers, such as India, China, and the EU, focusing heavily on the expansion of renewable energy, solar power will undoubtedly become one of the primary energy sources of the future.
With the scale construction and operation of solar power plants, how to monitor the running state of the plants in time and how to monitor the the upper-level system or dispatching system for power grid have become the urgent problems.
The solar power plant consists of a sophisticated infrastructure working in perfect sync to maximize the potential electricity production. Primary components are solar panels, inverters, solar controllers and transmission or energy storage systems.
● Because solar panels that track the sun's movement can receive 10% to 40% more energy than fixed panels, the system is set up with a central controller for adjusting the panel angles.
● Additionally, the facility has to record and transmit data about the current energy stability status, as well as check the field temperature and activate the cooling system as needed.
● Besides, remote monitoring is essential to scheduled maintenance, such as part replacement or solar panel cleaning, required for the power plant to maximize long term performance.
● Solar power plants are mostly located in remote areas because of the large amount of land area they occupy. Remote location poses a challenge for remote monitoring connectivity because wired Internet sources are rarely available at solar power production plant locations.
● Lastly, the system had to be able to effectively connect to a Modbus controller. Modbus is a communication protocol used for transmitting data over serial cables, and many devices in the solar facility used this protocol.
So the solution to be implemented had to overcome or work around these many obstacles. System requirements include:
● Remote field monitoring and control
● Ability to send alarms to mobile phones
● RS-485 interface and support for Modbus protocol
● Support for MQTT cloud protocol
● AWS cloud
● Ability to operate in extremely high temperatures
● Secure VPN tunnels
The Network Solution
The USR-G809 is an intelligent industrial grade gateway designed for critical infrastructure and industrial applications. It provides reliable and secure remote connectivity designed for harsh environments, giving operations and IT real-time awareness with remote monitoring. It combines IEEE 802.11b/g/n/ac WLAN and 4G LTE cellular technologies.
The N510-H7 MQTT Gateway is an industrial device specifically designed to implement an Industrial Internet of Things (IIoT) data collection system. It allows bidirectional communication between Modbus field equipment and an MQTT broker. It provides a Modbus RTU master interface on RS232/RS485/RS422 and Modbus TCP over Ethernet. Variables can be read from Modbus slave devices on change or at fixed time intervals and are sent to the MQTT broker with optional SSL/TLS client certificate authentication.
G809 provides Ethernet, serial, DI/DO and N510 provides Modbus bridging, making them ideal for connection to the many inverters, sensors, and other devices on the site.
The topology above outlines a simplified classic remote monitoring solution with a cellular connectivity device at its core.
The Solar controller is a brain of solar power plant operation and is generally capable of outputting system data via industrial protocols, such as Modbus TCP. The USR-N510-H7 gateway converts Modbus RTU/ASCII to Modbus TCP format. The best way to interpret this data is to use a cloud IoT platform where the data is aggregated and presented to the operator with performance metrics and suggested maintenance insights.
The G809, installed with a floating IP SIM card, acts as a VPN initiator connecting to a VPN server with a public fixed IP SIM card installed at the power company's remote location for secure site to site communication. Every time the cellular connection is reestablished, the VPN automatically takes effect.
Solar power generation is becoming more widely recognized and utilized as a renewable clean energy source. It is expected that the number of distributed solar plants being built and going into operation will continue to increase. These plants have critical monitoring and management needs, including real-time monitoring and messaging, control of panel tilt, power prediction, and power control systems.
In many cases, traditional wired infrastructure for monitoring and management is not feasible, due to costs or environmental concerns. Equipping these sites with appropriate 4G/LTE gateways is the ideal approach. They allow for remote management by mobile phone, and when equipped with a DI/DO interface can even allow for remote rebooting of an IPC through the DO relay mode. The presence of a serial interface on the gateways can eliminate the need for a PLC, reducing the overall cost.
USR-G809：4G Industrial cellular VPN router
USR-N510-H7：1 Port Serial to Ethernet Converter MQTT Gateway