Distributed Generation

SUBMITTED TO:- SUBMITTED

BY:- Mr.inderpreet Singh Mr. Naresh Chand

UIDNO-13MEL1007

Introduction Distributed generation in simple term can

be defined as a small-scale generation. It is active power generating unit that is connected at distribution level.

IEEE defines the generation of electricity by facilities sufficiently smaller than central plants, so as to allow interconnection at nearly any point in the power system, as Distributed Resources.

Electric Power Research Institute (EPRI) defines distributed generation as generation from a few kilowatts up to 50 MW.

Distributed generation, also called on-site generation, distributed energy or district energy, generates electricity from many small energy sources.

Most countries generate electricity in large centralized facilities, such as fossil fuel (coal, gas powered), nuclear, large solar power plants or hydropower plants. These plants have excellent economies of scale, but usually transmit electricity long distances and can negatively affect the environment.

Distributed generation allows collection of energy from many sources and may give lower environmental impacts and improved security of supply.

Distributed generation reduces the amount of energy lost in transmitting electricity because the electricity is generated very near where it is used, perhaps even in the same building. This also reduces the size and number of power lines that must be constructed

How Distributed Generation Works=?

DG as generation that is not centrally planned, centrally dispatched at present, usually connected to the distribution network, and smaller than 50-100 MW.

These generators are distributed throughout the power system closer to the loads as shown in the previous slide.

The DG penetration in the grid poses new challenges and problems to the network operators as these can have a significant impact on the system and equipment operations in terms of reliability, power quality, stability and safety for both customers and electricity supplier.

Types of Distributed Energy Resources

Cogeneration:-Distributed cogeneration sources use steam turbines, natural gas-fired fuel cells, micro turbines or reciprocating engines to turn generators. The hot exhaust is then used for space or water heating, or to drive an absorptive chiller for cooling such as air-conditioning.

Vehicle-to-grid:-Future generations of electric vehicles may have the ability to deliver power from the battery in a vehicle-to-grid into the grid when needed. An electric vehicle network could also be an important distributed generation resource.

Solar panel

Solar panel:-Popular sources of power for distributed generation are solar heat collection panels and solar panels on the roofs of buildings or free-standing. Solar heating panels are used mostly for heating water and when the water is heated into steam it can effectively and economically used in steam turbines to produce electricity.

Wind turbine

Wind turbine:-Another source is small wind turbines. These have low maintenance, and low pollution, however as with solar, wind energy is intermittent. Construction costs are higher than large power plants, except in very windy areas.

Waste-to-energy:- Municipal solid waste (MSW) and natural waste, such as sewage sludge, food waste and animal manure will decompose and discharge methane-containing gas that can be collected as used as fuel in gas turbines or micro turbines to produce electricity as a distributed energy resource.

Cost factors:- Co generators are also more expensive per watt than central generators. They find favor because most buildings already burn fuels, and the cogeneration can extract more value from the fuel. Local production has no electricity transportation losses on long distance power lines or energy losses from the Joule effect in transformers where in general 8-15% of the energy is lost

Modes of Power Generation DER systems may include the following

technologies:-Combined heat power (CHP)Fuel cellsMicro combined heat and power (Micro

CHP)Micro turbinesPhotovoltaic SystemsReciprocating enginesSmall Wind power systemsTri generation

Power Quality Issues:-A major issue related to interconnection of

distributed resources onto the power grid is the potential impacts on the quality of power provided to other customers connected to the grid.

Voltage Regulation:-Over-voltages due to reverse power flow: If the downstream DG output exceeds the downstream feeder load, there is an increase in feeder voltage with increasing distance. If the substation end voltage is held to near the maximum allowable value, voltages downstream on the feeder can exceed the acceptable range.

DG Grounding Issue:-A grid-connected DG, whether directly or through a transformer, should provide an effective ground to prevent un-faulted phases from over-voltage during a single-phase to ground fault. Proper grounding analysis of DG will ensure compatibility with grounding for both the primary and secondary power systems.

Harmonic Distortion:-Voltage harmonics are virtually always present on the utility grid. Nonlinear loads, power electronic loads effects of the harmonics include overheating and equipment failure, faulty operation of protective devices, nuisance tripping of a sensitive load and interference with communication circuits’

Islanding:-“Islanding” occurs when a small region of the power grid is isolated by broken lines, etc., and yet local sources provide enough power to keep the voltages up

In case the DG in the distribution system is capable to meet the load demand, DG can be operated in the island mode and continue to energize the distribution system.

From Utility Plant

070412

LINE BREAK

Generator

Island of “hot” lines

Transformer

Direct use of Distributed Generation:-

Photovoltaic (PV), wind, micro-combined heat & power (CHP) and many others produce power locally for direct use, reducing the need for transporting the energy across transmission and distribution grids.

Distributed Generation on the Grid

Advantages & DisadvantagesDistributed generation reduces the amount of

energy lost in transmitting electricity because the electricity is generated very near where it is used, perhaps even in the same building. This also reduces the size and number of power lines that must be constructed.

Disadvantages of DGPower QualityCost of Operation and MaintenanceLong Term Reliability of the UnitsInterconnection

ConclusionThe distributed generation help us to

reduce the cost of the transmission line and the transmission losses .distributed generation playing important role in the field of the electricity generation whereas Different issues related to power quality when DR is integrated with the existing power system has been discussed in the report .It can be concluded from this discussion that when interconnecting DR to the power system, these issues must be considered which could affect power quality and safety. Penetration of DR can be successfully integrated with the power system as long as the interconnection designs meet the basic requirements that consider not only power quality but also system efficiency and power reliability and safety.

References:-1. www.clarke-energy.com, retrieved 16 September 2013

2.http://www.forbes.com/sites/peterdetwiler/2012/12/26/solar-grid-parity-comes-to-spain/

3.http://oilprice.com/Latest-Energy-News/World-News/Spain-Achieves-Grid-Parity-for-Solar-Power .html

4.Boyle, Godfrey. Renewable Energy, Second Edition. Oxford: Oxford University Press, 2004, ISBN 0-19-26178-4. (my preferred text)

5.http://www.forbes.com/sites/peter detwiler/2012/12/26/solar-grid-parity-comes-to-spain

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