Digital Grid (1)

8/2/2019 Digital Grid (1)

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Contemporary Grids

Todays smart grid has been developed withextensive interconnections

These connections improves the reliability of

the grids Present smart grids does not support the high

penetrations of renewable energy for future

use To overcome this we need to measure power

levels and to control power flows.


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Problems of present power systems

Present day power systems have a varying

number of faults.

1. very less reliability.

2. effective control and management reg power

transfer not yet achieved.

3. Black outs due to synchronization.4. effective use and inter


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Digital grid

Advantages :-

1. More Robust and easily modifiable

2. can effectively include the power generated by

renewable sources like solar and wind energywithout the problem of compatabiliy.

3.In the smart grid, due to the complexity offluctuating impedences, full control of power

is not possible.4. Digital grid works asynchronously.

5.Digital grid manages the power flow at everylevel.


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Digital grid and networking

How is this related with digital grid?

Both are used in a similar maner.

A cell is given a specific IP address.

The Size of the cell varies from a city to a home.

When prompted, A digital Grid Controller sends the

required power in the required frequency,voltage

and power specifications to the specific IP

address.

The manner in which this is transferred is as follows


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A computer connects to the internet using a

internet passport address (IP Address).

The IP address identify's the computer in the

wide area network (WAN).

The computer connects to the main server via

LAN connected Routers.

These Routers Redirect Traffic back to the

destination server.

It is these Routers that Play an Important part.


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Digital Grid

Synchronous Power system is subdivided into

smaller digitalized cells.

These cells are connected asynchronously via

Digital Grid Routers.

DGR can send and recieve discrete powerpackets.

Digital grid controllers coordinate with DGRs to

absorb,consume and generate power.


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Features of the digital grid

Independent cells with mutuallyunsynchronized phases and frequencies areconnected using DGR

Digital grid controllers(DGC) are used totransfer information.

Each DGR and DGC has a CPU, memory, data

storage and network communications .Power and information can be integrated on a

single line.


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FUNCTIONS

Supports high penetration of renewable

energy.

Grid stability and redundancy.

Digital Power Trading.

Merging information and electric power.

Transition from the Conventional Grid


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Outlook of Digital grid

Japan is divided into three independent grids.

Peak demand of the grid in

north - 5.4GW

eastern-113GWwestern-56GW.

Capacity of conversion between

north-east is 0.6GW

east-west is 1.0GW Constant frequency 502 HZ in north and east

602HZ in west


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Digital Grid Router is composed of multiple IP-

addressed ac/dc/ac converters with a

common dc bus.

It can send discrete power pockets to any

location using voltage source converters over

existing transmission lines.


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Interconnections of Cells


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Digital grid controllers

DGC is attached to the controllers of the

generators and energy storage units.

Dispatches commands to the controllers of

generators, loads and energy storages.

Transmit information such as the status of

generators, the state of charge (SOC) of

energy storage, electric load, information, etc.


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Digital Electrical Power

Energy and information are integrated and

then delivered to a power line for

simultaneous power control.

Information can be transferred through two

networks-

Basic information through the power line.

Additionals through different network in advance.

Basic informations need lower bandwidth.


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Communication Technology in Digital

Grid

Modelled on architecture of internet and

internet protocol.

Cheaper and highly developing.

Includes routing optimization, automatic

address assigning, data error detection.


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Energy Exchange Procedure

DGR or DGC broadcasts a request to the other

equipment for energy exchange.

This include direction and quantity of real and

reactive powers starting and ending time of

exchange, minimum and maximum pricing

details.

Power equipments having those features reply

with an offer of trading conditions.


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Energy Exchange Procedure Cont

The DGR or DGC reserves the exchange withone of the repliers and get theacknowledgement.

This process is similar to ordinary reservation. Exchange takes place by the route which

minimizes the power losses.

Best route is chosen by focusing on economiccriteria and optimising based on physicallimitations.


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Every energy transaction between DGR and

DGC are recorded including time, price,

source, seller and buyer.


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Active and reactive power can be controlled

independently.

Power can be pushed in or pulled out from

each interconnection line within limit of DGR

capacity.


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Control of power flow with DGR

With synchronous grid magnitude of power

depends upon voltage,frequency,inductance

and angle(theta).

With DGR magnitude of power can be

controlled by Vx and

P=V*Vx(sin )/wL and Q=(V -V*Vx.cos)/wL


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Simulation Diagram


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AC- DC converter


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Instantaneous Power transfer at =0 and =30;


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Instantaneous Power transfer at =0 and =90;


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tac

Power loss in the transmission line


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Energy Control Technique


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Simulation result of energy control


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Conclusion

Digital grid provides robustness by dividing it

into asynchronous cells and by using energy

storage.It helps in accessing electrical energy

as accommodity.It may be applied to currentgrid step by step and may increase utilization

factor of transmission lines.It can be efficiently

implemented in developing countries asmuch investment has not been made in

synchronization.


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As it uses internet protocol for communication

which is cheap so digital electricity can be

made cheaper.

Digital Grid (1)

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