What’s On Smart Grid Communication Technologies?
Posted on: 10 January '12
The availability of robust communication technologies has transformed many industries such as TV, Radio, Internet and Airlines. Our aging electric grid is the last frontier that is now poised to undergo dramatic changes due to these smart technologies.
Why Smart technologies? Smart technologies allow for better control and monitoring of power, which translates into efficient consumption and distribution of energy. The advantage of smart grids compared to old electric grids is that it allows utilities to manage the flow of power through their systems while consumers can manage their appliances and use of energy at the household level.
The smart grid is a two-way transfer of energy and information. Smart grid devices monitor and control the entire energy chain from generation to consumption. This is achieved only if the devices are connected and can communicate their status with each other throughout this chain.
There are two kinds of smart grid technologies available namely wireline and wireless. Utilities can choose either one of the technologies depending on their unique needs and their existing infrastructure. A recent estimate lists that Wireline and wireless smart grid revenues are set to reach US$4.9 billion by 2016.
The wireline technologies available:
Power Line Communication (PLC) +–
Although utilities use this over longer distances to send data, it is more often used inside the building to achieve load shedding in AMI. It uses the existing power lines so that, you save on the cables and structural modifications to the building. It is a low-cost and a reliable way to achieve two-way communications. But the drawback is low bandwidth and point-to-point communication. Although long distance communication is possible, it poses significant challenges, especially in developing countries where the disturbances on transmission lines cause issues.
Broadband over Power Lines (BPL) +–
This technology transmits data over power lines (LV and MV) too, but at a higher bandwidth. The drawbacks associated with this are poor tolerance for noise in the line, limited deployments, poor interoperability, and lack of standards. Also the BPL products can cause electromagnetic interference.
Copper UTP +–
This offers choice of an analog modem, DSL or T1 speed and is widely available. The utilities do not like this option because they do not own it. The continuing expense can be another drawback.
Optical Fiber +–
This allows for secure and high-speed communication. But the installation costs are higher and it is point to point.
Internet Protocol (IP) +–
This is ubiquitous, low in cost and open standard protocol. Both wire line and wireless technologies use this protocol. Some drawbacks associated are less reliability and security.
Fiber to the Home (FTTH) +–
It has an unlimited bandwidth and is extremely fast, but the costs are higher.
Hybrid Fiber Coax (HFC) +–
It is fiber to the neighborhood or group of homes and coaxed into the home. It is not owned by utility, hence there is a lack of control.
The wireless technologies available:
MAS (Multiple Address System radio) +–
The SCADA and DA applications in many countries use these radios to communicate. It is flexible, reliable and compact. It can handle obstructions better and is also point to multipoint communication. However, the limited bandwidth is a drawback.
Paging Networks +–
This is used to send short messages to mobile devices. This is cost effective for one way messaging, although some standards exist. But the two way messaging can be expensive and most systems tend to be closed and proprietary.
Spread Spectrum Radio +–
This radio uses unlicensed 902-928MHz spectrum. It is point to multi point communication and is good for last mile connection. The line of sight requirement and continuous frequency hopping are the associated drawbacks.
WiFi is Open Standards IEEE 802.11b and 802.11g. You can attain bandwidth from 5 to 54mbs. The big plus point is that, it has very high market penetration and many devices already use WiFi communication. The limited distance of 100 to 250m and poor reception in buildings are the main drawbacks.
WiMAX adheres to IEEE 802.16d communication standard. You can get up to 75 MBS bandwidth over 10 to 30 miles. This bandwidth is a savior when an environmental disaster strikes a densely populated area and all smart meters start communicating the outages at same time. WiMAX can handle this increased traffic and because of this, WiMAX can be an ideal backhaul medium for in-premise WiFi and zigbee devices. Higher cost and poor market adoption are major constraints at the moment.
This uses IEEE 802.15.4 radio to communicate. It is a low cost and low power technology and uses unlicensed spectrum. Zigbee is gaining traction in the home energy market and multiple Zigbee enabled products are available in the market. Zigbee enables the smart meter to communicate with home appliances which helps to shed the load. Zigbee is constituted of mesh technology and this makes it more robust. Zigbee alliance has come up with Smart Energy profile (SEP 2.0) to ensure interoperability among home appliances but the limited distance and inability to penetrate concrete walls are major constraints.
3G Cellular +–
This is a low cost solution to enable long-range communication both within the substation and from home to the substation. It can be rolled out quickly using the existing cellular infrastructure. Most smart meters in future will use this technology to communicate with the MDMS system. The constraint is, it can become unreliable if natural disaster strikes and takes out cellular infrastructure.
TDMA Wireless (Cellular) +–
This is an Open IS-136 Standard, which was predominant in few countries. This technology has no future and is almost obsolete.
CDMA Wireless +–
The current 2G system uses IS-95 Standard. It is widely available and is cost effective, but heavy traffic can overwhelm the network. One such scenario is the simultaneous and widespread outage reporting by smart meters.
This again is widespread across the globe and provides a very cost effective means to achieve AMI. Like CDMA, heavy traffic can prove to be overwhelming in this case as well.
VSAT Terminal +–
This is widely used today for remote monitoring and control of transmission and distribution substations; proven and quick implementation. The cost is high and severe weather impacts the reliability.
Now we know why utilities are moving to smart grids. But what are the challenges? Is there a preferred smart technology as in wireless Vs wireline? Please do share your views.