Communication Technologies for Smart Grid Frame work.

N.Murugesan Fr. Director General

Central Power Research Institute Date: 04.12.15

1) Introduction. 2) Why it is important ?. 3) Requirements in terms of data delivery 4) Summary of Communication Development. 5) Various options – Advantages & Limitations. 6) Conclusion

Content

1) To share opportunities and challenges available in a network architecture for SG Frame work.. 2) For better understanding hybrid network architecture that meet heterogeneous electric system automation application requirements. 3) To provide a framework for electric utilities which plan to utilize new communication technologies to make the decision making process more effective and direct.

Introduction

Communication Protocol used inside sub- station

Communication network in an Utility

Source: CIGRE

Various Communication standards used outside substations.

Trend in the far future

Why it is important ? 1) The information exchange necessary to properly run Smart Grids has to cover all levels of the electric power system. 2) The immense increase in the volume of data to be transferred requires the application of advanced ICT in order to ensure consistency and security of the data transfer from level to level. 3) The efficiency of the ICT system architecture requires that all modules are designed in accordance with uniform, open and globally accepted standards.

Why it is important ? 4) Reliable and real-time information is the key factor for power delivery, profitability and customers satisfaction.

5) The operational and commercial Demands of electric utilities require a high-performance data communication network that supports both existing functionalities and future operational requirements. 6) Comm.Network constitutes the core of the electric system automation applications, the design of a cost- effective and reliable network architecture is crucial.

The main standardization aspects of the ICT for Smart Grids

Source : IEEE Std: 1646

Requirements in terms of data delivery

PS Communications

Application vs Service category

Source: Hand Book of Electrical Engineers – PS Operations – Chapter 16

Summary of Communication System development

1. Digital Communication ( SONET/ SDH)

2. Ethernet Communication in

Substations & Beyond.

3. Power line Communications

4. Satellite

5. Wireless Communication.

Classifications based on Performance/ cost of service. 1. Protection related. 2. Others like: Meter Reading & Control ( DLC/ AMR) Records & Asset Management. Maintenance & Constructions. Customer Enquiry Financial / HR Supply Chain and logistics Retail Customer Account Management Voice Communication

Corporate Computer Links

File Transfers Backups

Power System Marketing

Building Residential Metering Administration etc.

For Protection related Two technologies have emerged

as primary candidates for this

task.

1) SONET (Synchronous Optical Network) / SDH (Synchronous Digital Hierarchy)

2) Native switch-based Ethernet.

SONET in the US and Canada and SDH

networks in the rest of the world were used to

aggregate PDH networks together, to alleviate

dropout concerns, and to increase overall

network throughput.

SONET/SDH line rates.

PDH in brief

PDH had as well other shortcomings:

- no integrated network management

- no standardised management channel

- little flexibility

- Low degree of standardisation

- Limited capacity

Especially with the increasing demand for higher

bit-rates, accessing a single signal needs

cabinets full of multiplexers.

PDH in brief

• Each level multiplexes lower level almost synchronised signals

the bit-rate of the signals is allowed to vary slightly.

• All signal are read at a speed that guarantees transmission of the fastest

incoming bit-rate - bit-stuffing copes with slower bit-rates

Thus lower order signals float in the higher order data stream and require a

range of multiplexers to be accessed

Example:

Accessing a 2Mbit/s signal of a 140Mbit/s stream requires 6 Multiplexers -

it cannot betaken out directly from a 140Mbit/s stream

MUX

2Mbit/s

2Mbit/s

2Mbit/s

2Mbit/sMUX

8Mbit/s

8Mbit/s

8Mbit/sMUX

34Mbit/s

34Mbit/s

34Mbit/s140Mbit/s

MUX

MUX

8Mbit/s

8Mbit/s

8Mbit/s

MUX

34Mbit/s

34Mbit/s

34Mbit/s140Mbit/s8Mbit/s

34Mbit/s

OLTEOLTE

SDH introduced

To overcome PDH shortcomings, ITU-T defined a new transmission standard:

The SDH Synchronous Digital Hierarchy to …

access 2Mbit/s signals in any level of a datastream

have an integrated network management channel with routing functionality in every network element standardise the complete technology including - frame formats, - multiplexing schemes - synchronisation

allow bit-rates of up to 10 GBit/s in one signal

Advantage of SDH :

The SDH is based on global international standard.

Faster provision of services by remoter control.

In service performance monitoring of signals.

Possibility of control of circuit routing by customers.

Easier management of bandwidth.

Remote test access and maintenance from a central location.

Optical Transmission interfaces.

It will allow existing PDH hierarchies to be transported in

the SDH.

Reduced amount of equipment in the network and hence

savings on accommodation and power consumption.

Greater equipment reliability due to advanced electronic

circuitry and 1+1 protection.

Improved protection facilities for transmission failures.

Advance network management features.

Single stage multiplexing into the higher bit rates.

Cross connect functionality can be distributed around the

network.

Advantage of SDH (Contd.):

Software and configuration information can be

downloaded to network elements.

Reliability of ring networks using path protection.

Implementation of new broadband services such as

ATM is made easier.

There are cost saving and increased revenue to the

network operation.

Equipment from different manufacturer can be

connected together in the same network.

Advantage of SDH (Contd.):

COMPARISION OF SDH / PDH

PDH SDH

The reference clock is not

synchronized throughout the network

The reference clock is synchronized

throughout the network.

Multiplexing / Demultiplexing

operations have to be performed from

one level to the next level step by step.

The synchronous multiplexing results in

simple access to SDH system has

consistent frame structures throughout

the hierarchy.

PDH system has different frame

structures at different hierarchy levels.

SDH system has consistent frame

structures throughout the

hierarchy.

Physical cross-connections on the

same level on DDF are forced if any

Digital cross- connections are provided

at different signal levels and in different

ways on NMS

PDH SDH

G.702 specifies maximum 45Mpbs &

140Mpbs & no higher order (faster)

signal structure is not specified

G.707 specified the first level of

SDH.That is, STM-1, Synchronous

Transport Module 1st Order & higher.

(STM-1,STM-4,STM-16,STM-64)

PDH system does not bear capacity to

transport B-ISDN signals.

SDH network is designed to be a

transport medium for B-ISDN, namely

ATM structured signal.

Limited amount of extra capacity for

user / management

It will transport service bandwidths

Sufficient number of OHBs is available

Bit - by - bit stuff multiplexing Byte interleaved synchronous

multiplexing.

Comparison (Contd.)

Ethernet Bandwidth /

Distance

Structure Of Optical Fiber

Structure Of Optical Fiber(Contd..)

Schematic representation of Optical Fiber

Concept of Modes

Modes

Common designs of fiber

Step Index Fiber

1 2 3 4

n1

n2

n1

n2

R.I.

Common designs of fiber

Total internal reflection

Refraction

Core

n1

n2

n3

n4

n5

n6

Cladding n1>n2>n3>n4>n5>n6 etc.

Graded Index Fiber

Core

Cladding

r r

n2

n1

Refractive

Index n (r ) a

Graded Index Fiber

Single mode and Multimode fiber

Single mode and Multimode

Single mode and Multimode fiber

Core Cladding Jacket

Multimode 50micron 125 micron 250 micron

62.5micron 125 micron 250 micron

Single mode 9micron 125 micron 250 micron

Advantages of Optical communication

Explosive demand for higher bandwidth

Low bandwidth of copper

Nearly 25THz possible with fiber

Low Loss-Longer distance transmission(Less Repeaters)

No EMI in fiber-based telecom

Less cross-talk,more reliability

More secure communications

Lighter than copper

Lower cost per unit bandwidth(made of silica which is very

cheap)

Safer and more advantages

Very light weight and compact

Comparison of copper cable & Optical fiber cable with

same information carrying capacity

a) Ethernet offers more

efficient use of bandwidth

in point-to-point and mesh-

based topologies.

b) Ethernet network topology

is virtually unlimited and

includes resilient.

c) Lower initial cost.

Drawbacks:

a) It was not optimized for ring

network topologies.

b) Inadequate ring topology

support can result in a slow

response to fiber link failures

Advantages

a) SDH/SONET is a mature, well-

understood transport technology.

b) It is widely deployed at the

telecommunication network and is

regarded to be highly manageable.

c) Its network topology is very simple

with the resilient ring being the

most widely used option.

Draw backs

a) It is not optimized for highly

dynamic IP data traffic.

b) It requires configuration of fixed

point- to-point circuits.

c) Total available bandwidth must be

subdivided into fixed portions &

hence inefficient.

Status of Ethernet for Protection:

1) Accepted as communication standard for inside

substation communications.

2) Already IEC TC 57 have started working on

Ethernet based communication for Inter substation

communication.

3) There are few trial runs by few manufactures. In the

time to come more information would be available in

this area.

4) Native Ethernet links are most likely to be deployed

in brand new installations without significant

presence of legacy SDH equipment.

Power line communication

Benefits: 1) Broad coverage- Every where. 2) High bandwidth (better than ADSL 1.5 Mbps) 3) Cost effective – less overhead. 4) Easy installation. Drawbacks: 1) Lack of availability – Due to open circuit 2) Noise due to proximity to noise

environment. 3) High Attenuation 4) Security (UTP-EMI) Note: 1) All over world Utilities are positioning PL as communication media for AMR/ AMI. ( ERDF/ EU) 2) Few installations are there with PLC for AMR ( ENEL Italy)

Satellite communication

Benefits: 1) Extensive coverage. 2) It can reach where other media can not. 3) Used for GPS time synch. 4) For backup for existing comm. link. 5) High bandwidth Drawbacks: 1) Long delay due to round trip delay. 2) Performance is greatly affected by

climate and fading effect. 3) It is not cost effective. Note: 1) No utility in the world uses this as media for Control Application. 2) Non critical application like AMR could be used.

Wireless communication

Benefits: 1) Savings in cabling & rapid

installation. 2) Enable to arrive cost effective

solution. 3) Rapid installation possible. Drawbacks: 1) Susceptible for EMI. 2) Limitation in distance covered 3) Eavesdropping can occur & security

is a major issue. 4) Low QoS ( Quality of Service) Recent Developments in Wireless Technologies a) Wireless Sensor Network b) WiMax and Wireless Mesh Network

Wireless Sensor Network

How it works: 1) wireless sensor networks are composed

of a large number of low cost, low power and multifunctional sensor nodes that are small in size and communicate un-tethered over short distances

2) They capture noise level, temperature,

vibration, radiation, etc., as well as mapping such physicalcharacteristics of the environment to quantitative

measurements. 3) The collaborative nature of WSNs brings

greater fault tolerance, improved accuracy,larger coverage area and extraction of localized features.

Wireless Sensor Network

Applications: 1) Automatic Meter Reading functionality 2) Telemetry functionality ( obtain real time information). 3) Dynamic configuration functionality 4) Status monitoring functionality. Challenges: 1) Limited resources 2) Dynamic Topologies & environment changes 3) QoS concerns

WiMAX &

Wireless Mesh Network

1) It is a hybrid network architecture with wireless mesh domain. 2) Nodes in a mesh establish and maintain network connectivity. 3) Gateway & Bridge functionalities enable the integration of wireless domain ( WSN, Wi-Fi, WiMAX). 4) Finally an integrated wireless Mesh Network established. 5) Long distance communications up to 45 Kms between LCC & RCC is provided by WiMAX (ww interoperabilityfor Microwave Access – 75 Mbps, point to point wireless tech, non –line of sight, based on IEEE 802.16 )

WiMAX &

Wireless Mesh Network

Principle of Working

1) Communication Tech offers many choice to suit Utility’s requirements. 2) IEDs shall be intelligent and follow open Protocol for configuration, easy integration & seamless flow of information( To support SMART Grid). 3) Detailed cost vs benefit need to be worked out. 4) Careful follow up of Wireless Technology is needed as it is going to be one of the widely used in utility. 5) Deployment of PLC offers great incentive to utility. Every attempt shall be made to exploit it. 6) Security is one aspect Utility need to take care as it become hetrogeneous.

Conclusions

Questions?

Did I skip over the interesting part of my presentation?

Thanks for the opportunity

N.Murugesan

nmurugesan@yahoo.com

M: 09945939480