Solutions for powerline, wireless, and serial communications

Solutions for powerline, wireless, and serial communications (Maxim, www.maxim-ic.com/communications)

Overview

An electricity grid without adequate communications is simply a power “broadcaster.” It is through the addition of two-way communications that the power grid is made “smart.”

Smart grid communications enables utilities to achieve three key objectives:

  1. Intelligent monitoring,
  2. Security, and
  3. Load balancing.

Using two-way communications, data can be collected from sensors and meters located throughout the grid and transmitted directly to the grid operator’s control room. This added communications capability provides enough bandwidth for the control room operator to actively manage the grid.

The communications must be reliable, secure, and low cost. The sheer scale of the electrical grid network makes cost a critical consideration when implementing a communications technology.

Selecting a solution that minimizes the number of modems and concentrators needed to cover the entire system can dramatically reduce infrastructure costs.

At the same time, the selected technology must have enough bandwidth to handle all data traffic being sent in both directions over the grid network.


Communications networks and protocols

Communications in the smart grid can be broken into three segments:

Wide area network (WAN)

It covers long-haul distances from the command center to local neighborhoods downstream.

Neighborhood area network (NAN)

It manages all information between the WAN and the home area network using medium-voltage lines.

Home area network (HAN)

It extends communication to endpoints within the end-user home or business.

Each segment is interconnected through a node or gateway: a concentrator between the WAN and NAN and an e-meter between the NAN and HAN. Each of these nodes communicates through the network with adjacent nodes. The concentrator aggregates the data from the meters and sends that information to the grid operator.

The e-meter collects the power-usage data of the home or business by communicating with the home network gateway or functioning as the gateway itself.

The smart grid communications architecture

The smart grid communications architecture


Each segment can utilize different communications technologies and protocols depending on the transmission environments and amount of data being transmitted. In addition to the architecture choice between wireless and powerline communications (PLC), there are a variety of wireless and PLC protocols to choose among (Table 1).

NetworkProtocolAdvantagesDisadvantagesRecommendation
WANWireless (2G/3G/LTE cellular, GPRS)Extensive cellular infrastructure is readily available; large amount of aggregated data can be communicated over a long haulUtility must rent the infrastructure from a cellular carrier for a monthly access fee; utility does not own infrastructureWireless usually works best
HANWireless ISMLong range; leaps transformersCurrently proprietary; dead spots complicate installation and maintenanceUseful in some topologies, such as in the U.S.
IEEE® 802.15.4gLong range; leaps transformersNot yet an accepted standardUseful in some topologies
ZigBee®Low cost; low power consumption allows battery operation; well-known standardLow data rate; very short range; does not penetrate structures wellUnlikely to be used in NANs
First generation PLC (FSK, Yitran, Echelon®)Low costUnreliable; low bandwidthBandwidth and reliability inadequate for the smart grid
Early generation narrowband OFDMBetter range, bandwidth, and reliability than FSKDoes not cross transformers; does not coexist with first-generation PLCNot recommended for new designs due to cost and compatibility concerns
Broadband PLCHigh data rateDoes not cross transformersIncreases infrastructure cost, making it too costly for most large-scale deployments
G3-PLCHighly reliable long-range transmission; crosses transformers, reducing infrastructure costs; data rate supports frequent two-way communications; coexists with FSK; open standard; supports IPv6Not yet an accepted standardExcellent for NAN worldwide
HANZigBeeWell-known standard that offers low cost and low powerVery short range; does not penetrate structures wellWell suited for communication between water and gas meters
Wi-Fi®Popular technology with high data ratesMedium range; does not penetrate cement buildings or basementsGood for consumer applications, but no provisions for meeting utility objectives
First-generation PLC (FSK, Yitran, Echelon)Low costNot reliable in home environmentsUnlikely to be used in homes due to high levels of interference
Early generation narrowband OFDMBetter range, bandwidth, and reliability than FSKDoes not cross transformers; does not coexist with first-generation PLCNot recommended for new designs due to cost and compatibility concerns
Broadband PLCHigh bandwidthShort range is not sufficient for NANGood for consumer applications, but no provisions for meeting utility objectives
G3-PLCHighly reliable; sufficient data rate; IPv6 enables networking with many devicesNot yet an accepted standardExcellent for HAN worldwide

The WAN is the communications path between the grid operator and the concentrator. The WAN can be implemented over fiber or wireless media using Ethernet or cellular protocols, respectively.

Cellular or WiMAX® is most commonly used between the grid operator and the concentrator. The NAN is the path between the concentrator and the meter. It uses either wireless or PLC. Typically, the concentrator communicates with anywhere from a few to hundreds of meters, depending on the grid topology and the communications protocol used.

Today, there is no standard for this portion of the network, so most implementations use proprietary wireless or PLC technologies. Several standards bodies are currently working with utilities and technology providers to define standards for wireless and PLC protocols.

The IEEE 802.15.4g standard targets wireless; the IEEE P1901, OPEN meter, and ITU-T G.hnem standards are being developed for PLC (Table 2).

RegionWANNANHAN
North AmericaCellular, WiMAXG3-PLC, HomePlug®, IEEE 802.15.4g, IEEE P1901, ITU-T G.hnem, proprietary wireless, Wi-FiG3-PLC, HomePlug, ITU-T G.hn, Wi-Fi, ZigBee, Z-Wave
EuropeCellularG3-PLC, IEEE P1901, ITU-T G.hnem, PRIME, Wi-FiG3-PLC, HomePlug, ITU-T G.hn, Wi-Fi, Wireless M-Bus, ZigBee
ChinaCellular, band translated WiMAXG3-PLC, RS-485, wireless to be determinedG3-PLC, RS-485, Wi-Fi, to be determined
Rest of the WorldCellular, WiMAXG3-PLC, HomePlug, IEEE 802.15.4g, IEEE P1901, ITU-T G.hnem, PRIME, RS-485, Wi-FiG3-PLC, HomePlug, ITU-T G.hn, RS-485, Wi-Fi, Wireless M-Bus, ZigBee, Z-Wave

The HAN is used by utilities to extend the reach of their communication path to devices inside the home. This network can support functions such as cycling air conditioners off during peak load conditions, sharing consumption data with in-home displays, or enabling a card-activated prepayment scheme.

The arrival of electric/plug-in hybrid electric vehicles (EV/PHEVs) presents a special communications scenario for HANs.

Standards bodies are defining PLC protocols for communicating with vehicle charging systems. In addition to supporting the data requirements for smart grid activities, a HAN might also include: peer-to-peer (P2P) communications between devices inside the home; communications with handheld remote-control devices, lighting controls, and gas or water meters; as well as broadband traffic.

Protocols such as RS-485, ZigBee, Z-Wave®, and HomePlug are used for this network. If there is a separate home gateway, it is possible that additional protocols could be used to communicate with appliances, thermostats, and other devices.

Communications alternatives in the HAN can often coexist, but utility support will probably be limited to technologies needed to support the utility’s primary objectives.

Resource: Maxim (solutions for powerline, wireless, and serial communications); www.maxim-ic.com/communications


author-pic

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears. Professional in AutoCAD programming and web-design. Present on Google+.



6 Comments

  1. […] The following paragraphs introduce the basic system including subsystems and describe the motivations for communication. […]

  2. [...] their customers’ consumption profiles.In the same way, they will be useful for more and more power line communication and radio-frequency applications as well.In this area, prepayment systems are also more and more [...]


  3. adolfo.or
    May 27, 2013

    MUY BUENOS SUS APORTES.


    • tarigzroog
      Dec 30, 2012

      thanks

  4. [...] capacity and reliability. Information and communications technology integrationUnderlying smart grid communications infrastructure, whether using private utility communication networks (radio networks, meter mesh [...]

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