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FACTS devices

• The static device used to control the reactive electric power in the grid is called FACTS equipment.
• FACTS devices are static power-electronic devices installed in AC transmission networks to increase power transfer capability, stability, and controllability of the networks through series and/or shunt compensation.
• FACTS enhance the overall grid capacity and performance. They also increase the reliability and efficiency of your power system.
• The static synchronous series compensator (SSSC) and thyristor-controlled series capacitor (TCSC) are some of the FACTS control devices that provide series compensation to the reactance of the lines.
• static synchronous compensator (STATCOM) and static VAR compensator (SVC)  are FACTS devices that provide shunt compensation to transmission lines.

Correct option 3

Concept:

Tidal barrage

Tidal barrage systems are a tidal power generation method that works similarly to hydropower and have sluices that control the tidal flow to drive turbines and generate electricity

Benefits

• These types of dams can be used not only to produce renewable energy but also to reduce flooding.
• the global effects of climate change become more evident, the world is faced with the very real threat of rising sea levels.

Tidal barrages can be used to prevent flooding of low-lying areas - areas that already are at a high risk of flooding - by holding back or releasing water as necessary

Drawbacks

• Tidal barrages alter the flow of salt water in and out of estuaries, which can alter the quality of the seawater and thus negatively impact and displace marine life in the area
• barrage systems have high development costs and it can be difficult to justify using so much capital especially when the environmental threats are taken into consideration.

Barrage Designs

There are several different types and methods of producing electricity by the tidal barrage. However, there are two main classes that are used. Typically the type or class used depends on the environmental circumstances of an area.

Ebb Generation 

• Ebb generation uses gates that allow the water to fill a basin to the normal level, these gates are then closed at full tide.
• The water is then held back for a few hours while the tide recedes, the gates are then opened and the water flows through turbines for several hours generating electricity through to low tide

Two-way Generation

• Two-way generation uses turbines to generate power during both flood and ebb tide. All the water flows through the turbines and, unlike ebb generation, the water is not held back but allowed to flow freely and constantly turn the turbines

The correct answer is option 4):magnetic hydraulics

Concept:

• An electromagnet that uses hydraulics to power its generator and generate its current
• Hydraulic energy is a  classification of energy that takes advantage of the movement of water.
• It is also called water energy and it enables us to obtain electricity by making use of kinetic energy and potential energy from currents and waterfalls.
• It is clean and renewable energy that uses the force of streams, rivers and waterfalls.
• when we think of hydraulic energy, what comes to mind are hydroelectric power stations on dams in reservoirs.

Additional Information

• A non-renewable resource is a natural resource that cannot be readily replaced by natural means at a pace quick enough to keep up with consumption
• There are four major types of nonrenewable resources: oil, natural gas, coal, and nuclear energy

The correct answer is option 3):(hilly areas)

Concept:

The hilly areas are the preferred location for the hydroelectric power plant because of the following reason

• Availability of water: The rivers originate in the hilly regions plenty of water is available in hilly regions.
• The downstream water creates a lot of energy. This kinetic energy is utilized to rotate the turbine of the hydroelectric power plant
• The ideal location for the multipurpose dam is a hilly region.the narrow site valley widens upstream  of the dam
• In flat and desert areas sufficient water head cannot be obtained, deltas are not suitable because of high sedimentation levels.

The correct answer is option 3):(By interchanging all three supply line leads)

Concept:

• The direction of rotation of a 3-phase induction motor can be reversed by interchanging any two of the three motor supply lines.
• Let the phase sequence of the three-phase voltage applied to the stator winding be A-B-C.
• If this sequence is changed to A-C-B, it is observed that the direction of rotation of the field is reversed Such that the field rotates counterclockwise rather than clockwise.
• However, the number of poles and the speed at which the magnetic field rotates remain unchanged.
• Thus it is necessary only to change the phase sequence in order to change the direction of rotation of the magnetic field.
• For a three-phase supply, this can be done by interchanging any two of the three lines.

Correct option 1

Steam energy is normally generated from thermal power plants.

Concept:

Ocean Thermal Energy Conversion:

• In ocean thermal energy conversion hot water available at the surface of the ocean is used for the generation of steam.
• This generated steam is then put as input to the steam turbine to produce electricity.
• After putting pressure on the blades of the turbine and expanding over the turbine chamber this steam is taken out and cooled down through cold water available at the bottom of the sea.
• So, Ocean Thermal Energy conversion known as OTEC uses the water available at different temperatures in the sea.

Tidal Energy:

Tidal energy is a form of power produced by the natural rise and fall of tides caused by the gravitational interaction between the Earth, the sun, and the moon. 

The advantages of tidal energy are:

• Environment-friendly
• A highly predictable energy source
• High energy density
• Operational and maintenance costs are low
• An inexhaustible source of energy

The disadvantages of tidal energy are:

• High tidal power plant construction costs
• Negative influence on marine life forms
• Location limits
• The variable intensity of sea waves

Wave Energy:

• The kinetic energy possessed by huge waves near the seashore is used to generate electricity.
• The kinetic energy of the waves is used to rotate the turbine of the floating generators that generate electricity.
• Tidal Energy:
• Tidal energy is harnessed by constructing a dam across a narrow opening to the sea.
• A turbine fixed at the opening of the dam converts tidal energy to electricity.

Shaded pole induction motor:

• The shaded pole induction motor is simply a self-starting single-phase induction motor whose one of the poles is shaded by the copper ring

• The copper ring is also called the shaded ring

• This copper ring act as a secondary winding for the motor

• The part which is covered with the copper ring is called the shaded part and which is not covered by the rings is called the unshaded part

• The shaded pole motor rotates only in one particular direction, and the reverse movement of the motor is not possible

• The direction of rotation of the magnetic field is from the unshaded pole to the shaded pole

• This shading coil carries only induced current

• When the supply is connected to the windings of the rotor, the alternating flux induces in the core of the rotor

• The small portion of the flux link with the shaded coil of the motor as because it is short-circuited

• The variation in the flux induces the voltage inside the ring because of which the circulating current induces in it

• The circulating current develops the flux in the ring which opposes the main flux of the motor

• The flux induces in the shaded portion of the motor, and the unshaded portion of the motor has a phase difference

• The flux under the unshaded pole leads to the flux under the shaded pole

• The main motor flux and the shaded ring flux are also having a space displacement by an angle of 90°

• The flux in the unshaded portion leads to that in the shaded portion.

So, the shaded portion flux lags the unshaded portion flux

The disadvantages of shaded pole induction motor:

• Low power factor
• The starting torque is very poor
• The efficiency is very low as the copper losses are high due to the presence of the copper band
• The speed reversal is also difficult and expensive as it requires another set of the copper ring

The advantages of shaded pole induction motor:

• Very economical and reliable
• Construction is simple and robust because there is no centrifugal switch

Types of fault

1.) Symmetrical fault

• In such types of faults, all the phases are short-circuited to each other and connected to the earth.
• These faults do not disturb the symmetry of the fault i.e. the magnitude of all three phases remains equal and they are 120° displaced from each other.
• Two kinds of symmetrical faults include three-phase short-circuit (L-L-L) and (L-L-L-G) faults.

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​2.) Unsymmetrical fault

• Unsymmetrical faults involve only one or two phases.
• In unsymmetrical faults the three-phase lines become unbalanced.
• There are mainly three types namely line-to-ground (L-G), line-to-line (L-L), and double line-to-ground (LL-G) faults.

Electrostatic instruments

• The instrument which uses the static electric field for producing the deflecting torque is known as the electrostatic instrument.
• The electrostatic instrument works on the principle of mechanical interaction of the electrodes that consists of the opposite electrical charge.
• In the electrostatic instrument, the charge is stored between the plates.
• The electrostatic instrument consists of the charges of two opposite polarities and force of attraction occurs between these two plates.
• Because of the force of attraction, the movable plates move towards the fixed plates and store the maximum electrostatic energy.
• The capacitance multiplier used in the electrostatic instrument is used for the measurement of high AC Voltage.

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Synchronous motor

• ​A synchronous motor is a motor that rotates at the same speed as the revolving field in the machine which is equal to synchronous speed (N_s).
• Synchronous motors are not self-starting motors. This property is due to the inertia of the rotor; it cannot instantly follow the rotation of the magnetic field of the stator.
• Synchronous motors are capable of running at constant speed irrespective of the load acting on them.
• Synchronous motors have got higher efficiency.
• They run at the synchronous speed of the supply. They are generally used for constant speed operation under no load conditions such as to improve the power factor.
• Its efficiency ranges from 90 – 92%.