【IoT Communication Technology】—Power Line Communication (PLC)

Overview

With the diversification of IoT applications, the communication interface methods for connecting a large number of IoT devices are no longer limited to WiFi, Ethernet, and RS485/RS232. Furthermore, requirements for these networks extend beyond communication performance to include reliability, cost, etc., making PLC technology a viable option as well.

Power Line Carrier (PLC), also known as Power Line Communication, refers to a communication method that uses power lines as the information transmission medium for data transfer. This technology superimposes high-frequency signals carrying information onto the power lines for transmission. The receiving end then uses a relevant adapter to separate the high-frequency signals from the electrical current, thereby achieving data and signal transmission via the power lines.

Power line carrier communication can be conducted over high-voltage power lines (above 35KV), medium-voltage power lines (around 10KV), and low-voltage distribution lines (380V or 220V).

Development History

• Early 20th century: Power line telephony was an early attempt, filtering electrical signals from power lines within the same transformer's supply circuit.
• 1991: The Electronic Industries Association (EIA) in the United States established the power line home bus standard.
• 1997: Northern Telecom enabled power companies to transmit data and voice services over power lines at 1Mbps.
• Siemens' power line bus extended applications from homes to community telecom access points, achieving data transmission at 1Mbps.
• Thirteen companies including Cisco, Intel, HP, Panasonic, and Sharp formed the "HomePlug Powerline Alliance" to create a common standard for home power line network communication technology.
• German power industry giant RWE introduced a new technology called "Powerline," which could transmit various internet data signals through power lines, significantly advancing internet普及.
• 2001: Kyushu Electric Power, Tokyo Electric Power, Mitsubishi Electric, Fujitsu, Panasonic, and others in Japan collaborated to develop technology for transmitting and receiving images via power lines.
• 2001: China's State Grid Communication Center conducted PLC application experiments in residential areas in Beijing.
• Due to the特殊性 of power systems, most power companies worldwide have established dedicated communication networks for power systems primarily through self-construction to ensure stable and reliable communication.

Working Principle

When sending and receiving data between two devices, the data is modulated at the transmitter. The modulated signal is superimposed onto the AC or DC supply voltage. At the receiver, the data is extracted by separating the supply voltage and the modulated signal using a filter and then demodulating the modulated signal. PLC can be used on both AC and DC power lines. For example, it can be applied to batteries, lighting, electric vehicle charging, etc.

Types of PLC Technology

Related Standards

For home use, the IEEE 1901 standard specifies how existing AC wiring should be used globally for data. IEEE 1901 includes HD-PLC and HomePlug AV as baseline technologies. Any IEEE 1901 product can coexist and is fully interoperable with products using the same technology. On the other hand, mid-frequency home control devices remain fragmented, although X10 tends to dominate. For grid use, IEEE approved a low-frequency (≤500 kHz) standard named IEEE 1901.2 in 2013.

Several competing organizations have developed specifications, including the HomePlug Powerline Alliance (dissolved), the Universal Powerline Association (dissolved), and the HD-PLC Alliance. In October 2009, ITU-T adopted the G.hn/G.9960 recommendation as a networking standard for high-speed power line, coaxial cable, and telephone line communication. The National Energy Marketers Association (a US trade association) has also been involved in advocating for standards.

In July 2009, the IEEE Power Line Communication Standards Committee approved its draft broadband over power line standard. The final IEEE 1901 standard was published on December 30, 2010, incorporating features from both HomePlug and HD-PLC. Power line communication via devices compliant with IEEE 1901 and IEEE 1905 standards is indicated by the nVoy certification, pledged by all major suppliers of such devices in 2013. NIST has listed IEEE 1901 (HD-PLC, HomePlug AV) and ITU-T G.hn as "Additional Standards Identified by NIST for Further Review" for the US Smart Grid. IEEE also proposed a low-frequency, long-distance smart grid standard in 2013 called IEEE 1901.2.

Application Areas

• In-home networks: Can use the home's main power wiring to provide high-speed data transmission within the household.
• Broadband over Power Lines (BPL): Broadband internet access can be provided via outdoor power lines.
• Narrowband in-home applications: Low-rate services such as home automation and intercoms can be controlled and communicated via in-home power lines.
• Narrowband outdoor applications: Can be used for meter reading, remote monitoring, and control.

There are many applicable scenarios, not limited to the following areas:

• Advanced Metering Infrastructure (AMI) systems
• Microinverters
• HVAC systems
• Elevators
• Battery storage systems
• Smart streetlights
• Lighting control systems
• Intercom systems
• Surveillance camera systems

Resource Links

• PLC Alliance
• Shanghai Cloud Semiconductor Technology Co., Ltd.
• MegaChips Corporation
• Socionext Inc
• Xingtera