Advances in power systems

Presentation by:P. Sravan Kumar

U. Niranjan MaheshP. Siva sai Krishna

ANITS college of engineering ,sangivalasa ,Vishakhapatnam dist

Introduction Renewable resources Smart grids and Micro grids Power quality-FACTS HVDC Conclusion

Contents:

Renewable sources are solar and wind energy, biomass, bio-fuel, tidal, geothermal, wave energies.

Most commonly used are solar and wind energies. Solar power is conversion of sunlight into electricity The most advance way of conversion of sunlight into

electricity are: 1.concentrating solar thermal plant(CSP) 2.photovoltaic cells(PV) Wind power can be converted into electricity by using

turbines

Renewable resources

Solar energy -technology

Concentrating solar thermal plant (csp)

It contains; 1.Collector field 2.Turbine 3.Generator 4.Cooling tower 5.Transformer

PLF of CSP in range of 20% to 30%

Solar energy -technology

Solar photovoltaic cell

It contains1.Solar arrays2.Inverter3.transformer

PLF of PV in range of 15% to 20%

wind energy-technology

The amount of the energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed

PLF(plant load factor) of wind farm range of 20% to 30%

A microgrid is a small energy system capable of balancing captive supply and demand resources to maintain stable service within a defined boundary.

Micro grids

Combine various distributed energy resources (DER) to form a whole system that's greater than its parts.

Most microgrids can be further described by one of four categories:

1. Off-grid microgrids2. Campus microgrids3. Community microgrid4. Nano microgrids 

Micro grids (cont..)

Transmission losses get highly reduced

Provide high quality and reliable energy supply to critical loads

Micro grid results in substantial savings and cuts emissions without major changes to lifestyles.

Need of micro grid

Power sources in case of Microgrid ( often referred to as Micro sources ) are small and are located in close proximity to load

In peak load periods it prevents utility grid failure by reducing the load on the grid.

Significant environmental benefits made possible by the use of low or zero emission generators.

Advantages of micro grid

Smart grid

Network created through the combination of information, communication technology and electrical power system

Establishes a two-way communication between the utilities and the consumers

Anticipation of faults and helps in fault prevention

Reduces and shifts the peak demand

Continuous monitoring and feedback from network

What smart grid does ?

Over view of smart grid

Def: The quality of the voltage rather than power or electrical current.

Power is simply the flow of energy and current demanded by a load is largely uncontrollable.

Voltage provided should be as close to nominal voltage and wave form must be pure sine wave free form harmonics and other disturbances

Power Quality

They are:

1. Voltage sags 2. Micro-interruptions3. Long interruptions4. Voltage spikes 5. Voltage swells6. Harmonic distortion

Power quality problems

Solutions for PQ problems

FACTS (Flexible AC Transmission):P.E base systems & other static equipment that provide control of one or more AC transmission system parameters to enhance controllability & increase power transfer capability

In order to rectify the problems in power quality the FACTS devices are used.

FACTS

Control power so that it flows on the desired routes

Increase loading capacity of transmission lines.

Prevent blackouts.

Improve generation productivity

Effective use of upgrading/ uprating.

opportunities

Series compensation: In this FACTS are connected in series with power

system hence it works as a controllable voltage source

 In long lines, when a large current flows, this causes a large voltage drop. To compensate, series capacitors are connected, decreasing the effect of the inductance

FACTS key devices

Shunt compensation: In shunt compensation, power system is connected

in shunt (parallel) with the FACTS. It works as a controllable current sources. Shunt compensation is of two types:

1. Shunt capacitive compensation

2. Shunt inductive compensation

Cont(..)

It is a static synchronous generator as shunt static var compensator whose capacitive or inductive current can be controlled independent of the system voltage

The STATCOM scheme in parallel with AC power grid system and is controlled by a dynamic controller

Static Synchronous Compensator (STATCOM)

A High-voltage DC electric power transmission system uses DC for bulk transmission of electric power, in contract with the more common AC systems

HVDC allows power transmission between unsynchronized AC transmission systems

An HVDC link can be controlled independently of the phase angle between source and load, it can stabilize a network against disturbances due to rapid changes in power

HVDC Transmission

Converters

Smoothing reactors

Harmonic filters

Reactive power supplier

electrodes

Components of HVDC

Practical absence of transmission line length limitations

Interconnection of asynchronously operated power systems

No increase of short circuit power at connection point

Lesser corona loss and ratio interface

Can be used for submarine and underground transmission

Advantages of HVDC

Low cost of DC lines and cables

Simple in construction

Low cost for insulators and towers

Less line losses

Transmission line can be built in stages

Economic advantages

If the overhead transmission is long enough, say 1500 Km, the saving in capital costs and losses with a dc transmission line may be enough to pay for two converters. This distance is known as break-even distance.

This break-even distance is very subject to many factors

including the cost of the line, right-of-way, and often most important the politics of obtaining permission to build the line.

But it is important to recognize that while FACTS can play an important role in an effective use of ac transmission, it probably does not have too much influence on the break-even distance.

Long distance over head transmission

The role of HVDC is to interconnect ac systems where a reliable ac interconnection would be too expensive

Independent frequency and controlLower line cost Power control, voltage control and stability control possible

The large market potential for FACTS is within AC system on a value added basis where The existing steady-state phase angle between bus node is

reasonable The cost of FACTS solution is lower than the HVDC cost The required FACTS controller capacity is lesser than the

transmission rating

Whether HVDC or FACTS ?

HVDC transmission lines