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Smart communications, smarter grid
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With the smart grid emerging worldwide, a smart communications system is needed to
ensure its reliability and efficiency. The State Grid Corporation of China (SGCC),
which has set itself the target of establishing a unified strong smart grid by 2020, offers
some insights into the building of such a system.
The smart grid is coming
According to Wikipedia, a smart grid delivers electricity from suppliers to consumers
using digital technology with two-way communication to control appliances at
consumers' homes, in order to save energy, reduce cost and increase reliability and
transparency.
Countries around the world have different requirements when it comes to smart grids.
Some developed countries have heavily invested in their smart grid projects to secure
national energy supply, protect the environment, and boost the economy.
For example, the U.S. government has proposed a Unified National Smart Grid that
links all the nation's local electrical networks to solve the problem of power outages.
Europe initiated its SuperSmart Grid (SSG) plan, which connects Europe with northern
Africa, the Middle East, and the CIS. The system will integrate wind and solar power,
and smart grid capabilities into a comprehensive network. Japan will build its smart
grid by focusing on renewable energy like solar power.
China's smart grid will highlight ultra high voltage (UHV), ultra-long-haul
transmission, clean energy, automated power distribution, and bidirectional interaction
with consumers. To be economical, efficient, and reliable, the smart grid requires an
advanced communications system for real-time monitoring and dispatching, for
example, the wind power generated in Inner Mongolia, the solar power generated in
Tibet, and electricity transmitted from West to East China.
A communications network for the grid generally consists of a power distribution data
network and an integrated data network. Future power communications networks will
be expanded based on these two networks, forming a strong and comprehensive
infrastructure for the smart grid.
Ubiquitous interconnection
An automated power system mainly covers automatic power generation, transmission,
transformation, distribution, and usage. All these fields should also be covered by the
power line communications system.
Power generation: A smart grid would require that all large electric generators within
a country are inter-connected, and thus a large data network is required to ensure
reliable power distribution. Using automatic generating control (AGC), the
inter-connected generators can generate electricity based the demand, lowering costs,
while ensuring stable performance of the grid.
The smart grid can also help to integrate hydroelectric, thermal, nuclear, wind and solar
power together, realizing a comprehensive and stable grid. Yet all these need to be
backed up by a strong communications network for power distribution.
Power transmission: Transmission and transformation of power works closely with
the power line communications system. The sensors collect running data from knife
switches, transformers, and electrical lines (for example, current, voltage, power,
frequency, switch status, and phase), and then send it back to the control center.
Based on the real-time data from the communications system, operational personnel
can use the Supervisory Control and Data Acquisition (SCADA) system to realize
functions like telesignals, telemetry, remote control, and remote regulation. Connecting
various kinds of power equipment, the communications system is of great importance
to the grid.
Power distribution: Automatic power distribution requires a reliable communications
system that integrates wireless and wireline services. This system should ensure that all
automatic power distribution terminals can interact with one another and allow power
distribution switches to respond properly, thus minimizing the impact of power outages
in terms of area and duration.
Power usage: A ubiquitous wireless and wireline network would facilitate
communication between power-consuming devices and power-generating equipment,
ensuring power is generated based on demand and used effectively, and thus enabling a
stable and cost-effective power grid. Using WiMAX and passive optical network (PON)
with various split ratios, Huawei can provide the optimum solution for power
distribution and usage.
The integrated data network for power system is used to monitor production, weather,
unattended transformer stations, office automation, and more. Boasting a service
management system, the integrated data network is a ubiquitous network that covers
power generation plants, distribution centers, power supply units, service centers, and
future battery charging stations and communities with smart power supply.
With the multiprotocol label switching (MPLS) technology, Huawei provides virtual
private network (VPN) solutions to power distribution centers and power supply units,
helping them set up a highly reliable integrated data network with sound QoS. The
solutions also help enrich service offerings, including video, voice and data services.
Strong data network
The smart grid should be strong and reliable enough to accommodate power usage that
varies according to time and season. The load of a grid can fluctuate, for example, due
to short circuits and the startup or shutdown of heavy-load equipment. Electricity
frequency and voltage will change as a result, and the control center needs the
information through the integrated data network for proper processing, so as to avoid
power shortages and possible economic loss. Thus, a reliable data communications
network is a must for a strong smart grid.
The backbone network of SGCC's power distribution system has adopted Huawei's NE
series routers. Featuring high reliability, the routers separate the forwarding plane and
the control plane, plus offer standby backup for key hardware components. The
network uses a hierarchical architecture and has standby nodes for the national power
distribution center and other key branches, while remote backup is also adopted for the
key nodes. In a mesh or half mesh networking model, the network has no single link or
node, which ensures high reliability of the network services.
With bidirectional forwarding detection (BFD), the routing convergence of the state
grid communications network is reduced from the legacy 3-5 seconds to 50
milliseconds, realizing quick data transmission. In addition, nonstop routing (NSR)
allows uninterrupted routing during equipment upgrades, which ensures network
reliability and has no impact on the real-time application of the power system.
A strong power grid requires real-time power distribution, and this in turn requires that
the data communications system perform well to prevent delay, jitter, and packet loss.
The hierarchical QoS matches a queue to each power application to ensure that the
real-time VPN service has a higher priority than the non-real time one. Fast fault
detection also helps real-time operation. The Huawei NE routers support BFD fault
detection, and can detect a fault in 10 milliseconds and report it to the network
management system (NMS) for troubleshooting.
Smart grid, bright future
With the fast growth of Chinese economy, the power demand will keep increasing. In
addition, the power grid will require higher scalability to meet new requirements, for
example, transmitting power from Western to Eastern China, introducing ultra high
voltage (UHV) lines and transformer stations, and integrating clean energies such as
wind and solar power. In response, the communications equipment should have a large
capacity and flexible configuration.
A smart grid should support bidirectional interaction. China boasts 400 million homes,
a large number of SMEs and public facilities that consume power. To realize functions
like intelligent meter reading, dynamic electricity measurement, optimized resource
allocation, and online electricity sales, it requires a smart data network with a massive
number of IP addresses. In addition, a smart community would require automotive
power distribution. Reaching people's home appliances requires a large number of IP
addresses, and IPv4 is falling behind in meeting such requirements.
Though they have a great potential for future development, electric cars bring new
challenges to the power grids. Building battery charging stations and facilities will
further extend the power-line communication network to urban and rural areas. As a
result, a massive number of IP addresses are needed to support power distribution,
metering, service centers, and asset management.
Both the power distribution data network and the integrated data network should be
capable of supporting evolution from IPv4 to IPv6. As IPv4 and IPv6 will coexist for a
long time, networks should ensure interoperability between the two entities.
Huawei has been a leader in IPv6 technology; its homemade IPv6 chipset supports both
IPv4 and IPv6 protocols, plus large-scale and high-quality NAT64 and port network
address translation (PNAT).
All these help ensure compatibility between IPv4 and IPv6 applications, and the future
evolution of the power communication network.
SGCC has partnered with Huawei to build its power distribution data network and
integrated data network, laying a sound foundation for future smart grid. Besides
real-time and efficient communications, the data network has high flexibility and
scalability to support a strong power grid. SGCC is poised to build a cost-effective,
secure, stable, clean and eco-friendly smart grid.
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