POWER SYSTEM-II

The power output from a hydroelectric power plant depends on three parameters.

Low head hydro-plant is also known as

Demand factor is defined as

The area under a load curve gives

Which among the following is the most severe fault?

What is the value of the zero sequence current?

Which among the following methods is used for improving the system stability?

The transient stability limit of the power system can be increased by introducing

What do you mean by positive sequence network?

Define diversity factor and mention its significance.

What are the factors to be considered in selecting the site of a hydroelectric power plant? Write a short note on the selection of hydraulic turbine.

A generating station has the following data: installed capacity = 300 MW; capacity factor = 50%; annual load factor = 60%; annual cost of fuel, oil, etc. = $ 9 \times 10^7 $; capital cost = $ 10^9 $; annual interest and depreciation = 10%. Calculate (i) the minimum reserve capacity of the station and (ii) the cost per kWh generated.

Explain with neat sketch pumped storage peak load plant.

Estimate the generating cost per kWh delivered from a generating station from the following data: Plant capacity = 50 MW; Annual load factor = 40%; Capital cost = 1.2 crores; Annual cost of wages, taxation, etc. = 4 lakhs; cost of fuel, lubrication, maintenance, etc. = 1.0 paise/kWh generated. Interest 5% per annum, depreciation 6% per annum of initial value.

Deduce and draw the sequence network for LLG fault at terminal of unloaded generator.

A 25 MVA, 13.2 kV alternator with solidly grounded neutral has a subtransient reactance of 0.25 p.u. The negative and zero sequence reactances are 0.35 and 0.1 p.u. respectively. A single line to ground fault occurs at the terminals of an unloaded alternator; determine the fault current and line-to-line voltages on neglecting resistances.

Derive the expression of fault current for line-to-line fault on unloaded generator.

The line currents in phases a, b and c respectively are $ 500+j150 $, $ 100+j600 $ and $ -300+j600 $ referred to the same reference vector. Find the symmetrical component of current.

What is 'equal area criterion' and how is it derived from the swing equation? Explain the operation of a synchronous motor using this criterion when sudden increase in mechanical load on that motor occurs.

A 50 Hz synchronous generator having an internal voltage 1.2 pu, H = 5.2 MJ/MVA and a reactance of 0.4 pu is connected to an infinite bus through a double circuit line, each line of reactance 0.35 pu. The generator is delivering 0.8 pu power and the infinite bus voltage is 1.0 pu. Determine: maximum power transfer, steady state operating angle, and natural frequency of oscillation if damping is neglected.

What are the assumptions made during the stability analysis of a multi-machine system? Derive the equation for reduced admittance matrix.

A 50 Hz, 4-pole turbo alternator rated 150 MVA, 11 kV has an inertia constant of 9 MJ/MVA. Find the (i) stored energy at synchronous speed, (ii) rotor acceleration if the input mechanical power is raised to 100 MW when the electrical load is 75 MW and (iii) speed at the end of 10 cycles if acceleration is assumed constant at the initial value.

Enlist the effects of high-load factor on the operation of power plants.

The energy cost of a 100 MW steam station working at 40% load factor comes out to be 12 paise/kWh of energy generated. What will be the cost of energy generated if the load factor is improved to 60%? The fuel cost of the power station due to increased generation increase the annual generation cost by 5%.

Plant capacity factor

Surge tank

Reactor control of short circuit currents

Steady state stability

The power output from a hydroelectric power plant depends on three parameters.

Low head hydro-plant is also known as

Demand factor is defined as

The area under a load curve gives

Which among the following is the most severe fault?

What is the value of the zero sequence current?

Which among the following methods is used for improving the system stability?

The transient stability limit of the power system can be increased by introducing

What do you mean by positive sequence network?

Define diversity factor and mention its significance.

What are the factors to be considered in selecting the site of a hydroelectric power plant? Write a short note on the selection of hydraulic turbine.

A generating station has the following data: installed capacity = 300 MW; capacity factor = 50%; annual load factor = 60%; annual cost of fuel, oil, etc. = $ 9 \times 10^7 $; capital cost = $ 10^9 $; annual interest and depreciation = 10%. Calculate (i) the minimum reserve capacity of the station and (ii) the cost per kWh generated.

Explain with neat sketch pumped storage peak load plant.

Estimate the generating cost per kWh delivered from a generating station from the following data: Plant capacity = 50 MW; Annual load factor = 40%; Capital cost = 1.2 crores; Annual cost of wages, taxation, etc. = 4 lakhs; cost of fuel, lubrication, maintenance, etc. = 1.0 paise/kWh generated. Interest 5% per annum, depreciation 6% per annum of initial value.

Deduce and draw the sequence network for LLG fault at terminal of unloaded generator.

A 25 MVA, 13.2 kV alternator with solidly grounded neutral has a subtransient reactance of 0.25 p.u. The negative and zero sequence reactances are 0.35 and 0.1 p.u. respectively. A single line to ground fault occurs at the terminals of an unloaded alternator; determine the fault current and line-to-line voltages on neglecting resistances.

Derive the expression of fault current for line-to-line fault on unloaded generator.

The line currents in phases a, b and c respectively are $ 500+j150 $, $ 100+j600 $ and $ -300+j600 $ referred to the same reference vector. Find the symmetrical component of current.

What is 'equal area criterion' and how is it derived from the swing equation? Explain the operation of a synchronous motor using this criterion when sudden increase in mechanical load on that motor occurs.

A 50 Hz synchronous generator having an internal voltage 1.2 pu, H = 5.2 MJ/MVA and a reactance of 0.4 pu is connected to an infinite bus through a double circuit line, each line of reactance 0.35 pu. The generator is delivering 0.8 pu power and the infinite bus voltage is 1.0 pu. Determine: maximum power transfer, steady state operating angle, and natural frequency of oscillation if damping is neglected.

What are the assumptions made during the stability analysis of a multi-machine system? Derive the equation for reduced admittance matrix.

A 50 Hz, 4-pole turbo alternator rated 150 MVA, 11 kV has an inertia constant of 9 MJ/MVA. Find the (i) stored energy at synchronous speed, (ii) rotor acceleration if the input mechanical power is raised to 100 MW when the electrical load is 75 MW and (iii) speed at the end of 10 cycles if acceleration is assumed constant at the initial value.

Enlist the effects of high-load factor on the operation of power plants.

The energy cost of a 100 MW steam station working at 40% load factor comes out to be 12 paise/kWh of energy generated. What will be the cost of energy generated if the load factor is improved to 60%? The fuel cost of the power station due to increased generation increase the annual generation cost by 5%.

Plant capacity factor

Surge tank

Reactor control of short circuit currents

Steady state stability

Describe phase shift in Star-delta Transformers.

Define voltage unbalance.

Explain the term 'voltage stability'.

What is 'equal area criterion'?

Differentiate between steady state stability and transient stability of power system.

What for surge tank is provided?

What are the advantages of using per unit system?

Define stability limit of power system.

What is sub-station? Name the factors that should be taken care of while designing and erecting a sub-station.

What is reheater?

What are the functions of economizer and superheater in a thermal power plant?

A thermal power plant spends rupees 25 lakhs in one year for coal consumption. The coal has heating value of 5000 kcal/kg and costs rupees 500 per ton. If the thermal efficiency is 35% and electrical efficiency is 90%, find the average load on the power plant.

What is sub-station? Name the factors that should be taken care of while designing and erecting a sub-station.

Give a general layout of a pumped hydro plant. Explain the function of different components in plant.

A 500 MVA, 11 kV, 3 phase alternator was subjected to different types of faults. The fault currents are as given below: Three phase fault - 2000 A; Line to line fault - 2600 A; Line to ground fault - 4200 A. The generator neutral is solidly grounded. Find the values of the sequence reactances of the alternator. Assume that generator has negligible winding resistance.

What do you understand by positive, negative and zero sequence impedances? Discuss them with reference to synchronous generators, transformers and transmission lines.

The voltages across a 3-phase unbalanced load are $ V_a = 300 V $, $ V_b = 300\angle -90^{\circ} V $ and $ V_c = 800\angle -143.1^{\circ} V $, respectively. Determine the sequence components of voltages. Phase sequence is abc.

Define the following with example in connection with a power supply system: (i) Connected load (ii) Maximum demand (iii) Demand factor (iv) Load factor.

A generating station has a connected load of 450 MW and a maximum demand of 250 MW; the units generated being $ 615 \times 10^6 $ per annum. Calculate the demand factor and load factor.

Explain the term sequence impedance for transmission lines with example and mathematical expressions.

Prove that a line-to-ground fault at the terminals for a synchronous generator with solidly grounded neutral is more severe than a three-phase fault.

What is a 3-phase unsymmetrical fault? Discuss the different types of symmetrical fault that can occur on? Obtain an expression for critical angle with the aid of equal area criterion.

Derive the swing equation of synchronous machine swinging against an infinite bus. Clearly state the assumption in deducing the swing equation.

Distinguish between steady state, transient and dynamic stability. What do you mean by critical clearing angle?

Describe phase shift in Star-delta Transformers.

Define voltage unbalance.

Explain the term 'voltage stability'.

What is 'equal area criterion'?

Differentiate between steady state stability and transient stability of power system.

What for surge tank is provided?

What are the advantages of using per unit system?

Define stability limit of power system.

What is sub-station? Name the factors that should be taken care of while designing and erecting a sub-station.

What is reheater?

What are the functions of economizer and superheater in a thermal power plant?

A thermal power plant spends rupees 25 lakhs in one year for coal consumption. The coal has heating value of 5000 kcal/kg and costs rupees 500 per ton. If the thermal efficiency is 35% and electrical efficiency is 90%, find the average load on the power plant.

What is sub-station? Name the factors that should be taken care of while designing and erecting a sub-station.

Give a general layout of a pumped hydro plant. Explain the function of different components in plant.

A 500 MVA, 11 kV, 3 phase alternator was subjected to different types of faults. The fault currents are as given below: Three phase fault - 2000 A; Line to line fault - 2600 A; Line to ground fault - 4200 A. The generator neutral is solidly grounded. Find the values of the sequence reactances of the alternator. Assume that generator has negligible winding resistance.

What do you understand by positive, negative and zero sequence impedances? Discuss them with reference to synchronous generators, transformers and transmission lines.

The voltages across a 3-phase unbalanced load are $ V_a = 300 V $, $ V_b = 300\angle -90^{\circ} V $ and $ V_c = 800\angle -143.1^{\circ} V $, respectively. Determine the sequence components of voltages. Phase sequence is abc.

Define the following with example in connection with a power supply system: (i) Connected load (ii) Maximum demand (iii) Demand factor (iv) Load factor.

A generating station has a connected load of 450 MW and a maximum demand of 250 MW; the units generated being $ 615 \times 10^6 $ per annum. Calculate the demand factor and load factor.

Explain the term sequence impedance for transmission lines with example and mathematical expressions.

Prove that a line-to-ground fault at the terminals for a synchronous generator with solidly grounded neutral is more severe than a three-phase fault.

What is a 3-phase unsymmetrical fault? Discuss the different types of symmetrical fault that can occur on? Obtain an expression for critical angle with the aid of equal area criterion.

Derive the swing equation of synchronous machine swinging against an infinite bus. Clearly state the assumption in deducing the swing equation.

Distinguish between steady state, transient and dynamic stability. What do you mean by critical clearing angle?

In thermal power plant, the dust of flue gas is trapped by

The pulverized coal is

On which one of the following cycles, does a modern steam power plant work?

In a system if the base load is the same as the maximum demand, the load factor will be

The daily energy produced in a thermal power station is 720 MWh at a load factor of 0.8. What is the maximum demand of the station?

The positive sequence component of voltage at the point of fault becomes zero when it is a

A balanced three-phase system consists of

The line current of a three-phase power supply is $ I_R = 3+j5 A $, $ I_Y = 2+j2 A $, $ I_B = -2-j1 A $. The zero sequence current will be

Which of the following faults is most severe?

What is the value of transient stability limit?

What are the factors to be considered for selection of site for a hydro power plant?

Classify hydro power plant.

What do you mean by base load and peak load substation?

Explain the term two-part tariff.

A consumer has an annual consumption of 70080 kWh. The charge is 100 per kW of maximum demand plus 5 paise per kWh. Find the annual bill and the overall cost per kWh if the load factor is 40%. Also calculate the annual bill and overall cost per kWh if consumption is increased by 50% with the same load factor.

Derive the total complex power in a three-phase circuit in terms of symmetrical components.

Show that the zero sequence line current is zero in the absence of neutral current.

Calculate the three-phase voltages from the positive, negative and zero sequence voltage $ (312.34+j101.74)V $, $ (-25.80-j163.63)V $, $ (-86.54+j61.89)V $. Phase sequence is abc.

Define negative and zero sequence component.

Draw the positive, negative and zero sequence network of a star-connected synchronous machine.

One line diagram of a small power system is given below. Draw the zero sequence networks: Generator 1 = $ X_{10} $, Generator 2 = $ X_{20} $, Line NU = $ X_{L0} $, Transformer T1 = $ X_{t10} $, Transformer T2 = $ X_{t20} $.

For a three-phase unloaded alternator having neutral grounded through impedance $ Z_n $ and fault impedance $ Z_f $ draw the phase and sequence network under single-line to ground fault. Also derive the expression for positive, negative and zero sequence current in a three-phase unloaded alternator.

A 50 MVA, 11 kV, three-phase alternator was subjected to different types of faults. The fault currents were: Three-phase fault current: 1800 A; Line-to-line fault current: 2500 A; Single-line to ground fault current: 4000 A. The alternator is solidly grounded. Find the per unit value of three-sequence reactance of the alternator. Neglect resistance.

Derive the expression for swing equation of a synchronous machine.

A 50 Hz, 2-pole turbo generator rated 50 MVA, 13.2 kV has an inertia constant of $ H=5 \text{ MJ/MVA} $. Determine the kinetic energy stored in the rotor at synchronous speed. Determine the acceleration if the input less the rotational losses is 65000 HP and the electric power developed is 40 MW. If the acceleration computed for the generator is constant for a period of 10 cycles, find the change in torque angle in that period and rotor speed in revolution per minute at the end of this period. Assume that the generator is synchronized with a large system and has no accelerating torque before the 10 cycle period begins. (1 HP = 735 watt).

In a solidly grounded three-phase alternator, double-line to ground fault takes place between phase b and phase c with zero fault impedance. Determine the positive, negative and zero sequence component of the current. Also find the value of neutral current.

A 25 MVA, 13.2 kV alternator with solidly grounded neutral has sub-transient reactance of 0.25 per unit. The negative and zero sequence reactances are 0.35 and 0.1 per unit respectively. Determine the fault current and line-to-line voltages at the fault when a double-line to ground fault occurs at the terminals of the alternators.

(a) Coal handling in thermal power plant.

(b) Steady-state stability

(c) Power angle curve

In thermal power plant, the dust of flue gas is trapped by

The pulverized coal is

On which one of the following cycles, does a modern steam power plant work?

In a system if the base load is the same as the maximum demand, the load factor will be

The daily energy produced in a thermal power station is 720 MWh at a load factor of 0.8. What is the maximum demand of the station?

The positive sequence component of voltage at the point of fault becomes zero when it is a

A balanced three-phase system consists of

The line current of a three-phase power supply is $ I_R = 3+j5 A $, $ I_Y = 2+j2 A $, $ I_B = -2-j1 A $. The zero sequence current will be

Which of the following faults is most severe?

What is the value of transient stability limit?

What are the factors to be considered for selection of site for a hydro power plant?

Classify hydro power plant.

What do you mean by base load and peak load substation?

Explain the term two-part tariff.

A consumer has an annual consumption of 70080 kWh. The charge is 100 per kW of maximum demand plus 5 paise per kWh. Find the annual bill and the overall cost per kWh if the load factor is 40%. Also calculate the annual bill and overall cost per kWh if consumption is increased by 50% with the same load factor.

Derive the total complex power in a three-phase circuit in terms of symmetrical components.

Show that the zero sequence line current is zero in the absence of neutral current.

Calculate the three-phase voltages from the positive, negative and zero sequence voltage $ (312.34+j101.74)V $, $ (-25.80-j163.63)V $, $ (-86.54+j61.89)V $. Phase sequence is abc.

Define negative and zero sequence component.

Draw the positive, negative and zero sequence network of a star-connected synchronous machine.

One line diagram of a small power system is given below. Draw the zero sequence networks: Generator 1 = $ X_{10} $, Generator 2 = $ X_{20} $, Line NU = $ X_{L0} $, Transformer T1 = $ X_{t10} $, Transformer T2 = $ X_{t20} $.

For a three-phase unloaded alternator having neutral grounded through impedance $ Z_n $ and fault impedance $ Z_f $ draw the phase and sequence network under single-line to ground fault. Also derive the expression for positive, negative and zero sequence current in a three-phase unloaded alternator.

A 50 MVA, 11 kV, three-phase alternator was subjected to different types of faults. The fault currents were: Three-phase fault current: 1800 A; Line-to-line fault current: 2500 A; Single-line to ground fault current: 4000 A. The alternator is solidly grounded. Find the per unit value of three-sequence reactance of the alternator. Neglect resistance.

Derive the expression for swing equation of a synchronous machine.

A 50 Hz, 2-pole turbo generator rated 50 MVA, 13.2 kV has an inertia constant of $ H=5 \text{ MJ/MVA} $. Determine the kinetic energy stored in the rotor at synchronous speed. Determine the acceleration if the input less the rotational losses is 65000 HP and the electric power developed is 40 MW. If the acceleration computed for the generator is constant for a period of 10 cycles, find the change in torque angle in that period and rotor speed in revolution per minute at the end of this period. Assume that the generator is synchronized with a large system and has no accelerating torque before the 10 cycle period begins. (1 HP = 735 watt).

In a solidly grounded three-phase alternator, double-line to ground fault takes place between phase b and phase c with zero fault impedance. Determine the positive, negative and zero sequence component of the current. Also find the value of neutral current.

A 25 MVA, 13.2 kV alternator with solidly grounded neutral has sub-transient reactance of 0.25 per unit. The negative and zero sequence reactances are 0.35 and 0.1 per unit respectively. Determine the fault current and line-to-line voltages at the fault when a double-line to ground fault occurs at the terminals of the alternators.

(a) Coal handling in thermal power plant.

(b) Steady-state stability

(c) Power angle curve

Which of the following power stations is mainly used to cover peak load on the system?

For the hydroelectric power plants

On what factor, the fixed charge is dependent in a two-part tariff?

Fault calculations using computer are usually done by

What is the value of zero sequence current?

The following sequence currents were recorded in a power system under a fault condition: $ I_{\text{positive}} = j1.753 \text{ p.u.} $, $ I_{\text{negative}} = -j0.6 \text{ p.u.} $, $ I_{\text{zero}} = -j1.153 \text{ p.u.} $ The fault is

If all the sequence voltages at the fault point in a power system are equal, then the fault is a

Which of the following networks gets affected by the method of neutral grounding?

For 800 MJ stored energy in the rotor at synchronous speed, what is the inertia constant (H) for a 50-Hz, 4-pole turbo-generator rated 100 MVA, 11 kV?

Which of the following cannot be determined from equal area criterion?

What are the factors to be considered for selection of site for a thermal power station?

Draw the schematic layout of a typical coal fired power station.

Explain the role of economizer and superheater in a thermal power plant.

Define load factor and diversity factor. What is the impact of diversity factor?

An electric supply undertaking has to cater to a demand of two consumers A and B, each having a maximum demand of 5 kW. Variation of loads for these consumers are given below :
Consumer A: midnight to 7 AM: 200W; 6 PM to 7 PM: 1500W; 7 PM to 9 PM: 5000W; 9 PM to midnight: 800W.
Consumer B: midnight to 6 AM: 400W; 6 AM to 12 Noon: 1600W; 12 Noon to 2 PM: 5000W; 2 PM to 7 PM: 600W; 7 PM to 11 PM: 3600W; 11 PM to midnight: 600W.

Draw the separate load curve for each consumer and the system load curve. Find the maximum demand on the system. Also, calculate the load factor and the diversity factor.

What are different types of reactance of an unloaded synchronous machine under short-circuit condition? Discuss them briefly using approximate circuit model.

A rated generator synchronous 500 kVA, 440 V, 0.1 p.u. subtransient reactance is supplying a passive load of 400 kW at 0.8 lagging power factor. Calculate the initial symmetrical r.m.s. current for a three-phase fault at generator terminal.

Define positive, negative and zero-sequence components.

Write the equation to transform phase voltage into sequence voltage.

The voltages across a three-phase unbalanced load are $ V_a = 200 V $, $ V_b = 200\angle -90^{\circ} V $, $ V_c = 600\angle 140^{\circ} V $ respectively. Determine the sequence component of voltages. Phase sequence is abc.

Calculate the sequence component of three-phase star-connected balanced supply voltages.

Derive the sequence component of a transmission line having $ X_s $ (self-reactance of each line) and $ X_m $ (mutual reactance of any line pair). The series resistance of the line may be ignored.

For a three-phase unloaded alternator with neutral grounded through impedance $ Z_n $ and fault impedance $ Z_f $, draw the phase and sequence network for an L-L fault. Also derive the expression for the sequence component of the current in a three-phase unloaded alternator for L-L fault.

A 20 MVA, 33 kV, three-phase alternator is subjected to different types of short-circuit tests. The fault currents were: three-phase fault current - 300 A; line to line fault current - 400 A; single-line to ground fault current - 600 A. The alternator is solidly grounded. Find the per unit value of three-sequence reactance of the alternator. Neglect resistance.

Derive an expression for the maximum power transfer between two nodes. Show that this power is maximum when $ X = \sqrt{3}R $, where X and R are reactance and resistance of the system respectively.

A motor is receiving 30% of the power that it is capable of receiving from an infinite bus. If the load on the motor is doubled, calculate the maximum value of $ \delta $ during the swing of the rotor around the equilibrium position.

(a) Transient stability

(b) Equal area criterion

(c) Hydrothermal scheduling

Which of the following power stations is mainly used to cover peak load on the system?

For the hydroelectric power plants

On what factor, the fixed charge is dependent in a two-part tariff?

Fault calculations using computer are usually done by

What is the value of zero sequence current?

The following sequence currents were recorded in a power system under a fault condition: $ I_{\text{positive}} = j1.753 \text{ p.u.} $, $ I_{\text{negative}} = -j0.6 \text{ p.u.} $, $ I_{\text{zero}} = -j1.153 \text{ p.u.} $ The fault is

If all the sequence voltages at the fault point in a power system are equal, then the fault is a

Which of the following networks gets affected by the method of neutral grounding?

For 800 MJ stored energy in the rotor at synchronous speed, what is the inertia constant (H) for a 50-Hz, 4-pole turbo-generator rated 100 MVA, 11 kV?

Which of the following cannot be determined from equal area criterion?

What are the factors to be considered for selection of site for a thermal power station?

Draw the schematic layout of a typical coal fired power station.

Explain the role of economizer and superheater in a thermal power plant.

Define load factor and diversity factor. What is the impact of diversity factor?

An electric supply undertaking has to cater to a demand of two consumers A and B, each having a maximum demand of 5 kW. Variation of loads for these consumers are given below :
Consumer A: midnight to 7 AM: 200W; 6 PM to 7 PM: 1500W; 7 PM to 9 PM: 5000W; 9 PM to midnight: 800W.
Consumer B: midnight to 6 AM: 400W; 6 AM to 12 Noon: 1600W; 12 Noon to 2 PM: 5000W; 2 PM to 7 PM: 600W; 7 PM to 11 PM: 3600W; 11 PM to midnight: 600W.

Draw the separate load curve for each consumer and the system load curve. Find the maximum demand on the system. Also, calculate the load factor and the diversity factor.

What are different types of reactance of an unloaded synchronous machine under short-circuit condition? Discuss them briefly using approximate circuit model.

A rated generator synchronous 500 kVA, 440 V, 0.1 p.u. subtransient reactance is supplying a passive load of 400 kW at 0.8 lagging power factor. Calculate the initial symmetrical r.m.s. current for a three-phase fault at generator terminal.

Define positive, negative and zero-sequence components.

Write the equation to transform phase voltage into sequence voltage.

The voltages across a three-phase unbalanced load are $ V_a = 200 V $, $ V_b = 200\angle -90^{\circ} V $, $ V_c = 600\angle 140^{\circ} V $ respectively. Determine the sequence component of voltages. Phase sequence is abc.

Calculate the sequence component of three-phase star-connected balanced supply voltages.

Derive the sequence component of a transmission line having $ X_s $ (self-reactance of each line) and $ X_m $ (mutual reactance of any line pair). The series resistance of the line may be ignored.

For a three-phase unloaded alternator with neutral grounded through impedance $ Z_n $ and fault impedance $ Z_f $, draw the phase and sequence network for an L-L fault. Also derive the expression for the sequence component of the current in a three-phase unloaded alternator for L-L fault.

A 20 MVA, 33 kV, three-phase alternator is subjected to different types of short-circuit tests. The fault currents were: three-phase fault current - 300 A; line to line fault current - 400 A; single-line to ground fault current - 600 A. The alternator is solidly grounded. Find the per unit value of three-sequence reactance of the alternator. Neglect resistance.

Derive an expression for the maximum power transfer between two nodes. Show that this power is maximum when $ X = \sqrt{3}R $, where X and R are reactance and resistance of the system respectively.

A motor is receiving 30% of the power that it is capable of receiving from an infinite bus. If the load on the motor is doubled, calculate the maximum value of $ \delta $ during the swing of the rotor around the equilibrium position.

(a) Transient stability

(b) Equal area criterion

(c) Hydrothermal scheduling

What are superheater and reheater?

On what factors does the power output of hydro-plant depends?

What is load duration curve? What information does it provides?

Name some of the categories of heat losses in a thermal plant.

Define critical clearing angle in equal area criterion?

Why ash handling plant necessary in thermal power plant?

What is two par tariff?

What is hydrograph? What information does it provides?

List the different methods to improve transient stability.

Define the sequence impedances.

Define the terms plant capacity factor and plant use factor and explain their importance in an electrical power system. Also explain the effect of the load factor on the cost of generation.

The power station supplies the peak loads of 25 MW, 20 MW and 30 MW to three localities. The annual load factor is 0.60 pu and the diversity of the load at the station is 1.65 pu. Calculate: (a) The maximum demand on the station. (b) The installed capacity. (c) The energy supplied in a year.

Derive the sequence impedance of transmission lines.

A set of unbalanced line currents in a three phase four wire system in as follows: $ I_a = -j6 A $, $ I_b = (-8+j5) A $ and $ I_c = 7 A $. Determine the zero sequence, positive sequence and negative sequence components of the current.

Prove that a line-to-ground fault at the terminals for a synchronous generator with solidly grounded neutral is more severe than a three-phase fault.

A 100 MVA, 11 KV, three-phase synchronous generator was subjected to different type of faults. The faults currents are as follows: LG fault - 4200 A; LL fault - 2600 A; LLL fault - 2000 A. The generator neutral is solidly grounded. Find the per unit values of the three sequence reactances of the generator.

Distinguish between steady state and transient stability of a power system and also discuss the factors on which these depends.

A 100 MVA, 2 pole, 60 Hz generator has a moment of inertia of $ 50 \times 10^3 \text{ kg-m}^2 $. Determine the following: (a) The energy stored in the rotor at the rated speed (b) The angular Momentum M and (c) The inertia constant H.

A transmission line of reactance 0.1 H and resistance 5 ohms is suddenly short circuited at $ t = 0 $ seconds at the bar end as shown in the figure [with an AC source $ V=100 \sin(100\pi t+15^{\circ}) $]. Write the expression for the short circuit current $ i(t) $ with a neat diagram. Find approximately the value of the first current maximum (maximum momentary current). Assume that the first current maximum occurs at the same time as the value of the first current maximum of the short circuit current.

Three 60 MVA ac generators, each having 15% reactance are connected via three 36 MVA reactors each of 10% reactance to a common busbar. The feeders are each connected to the junction of each alternator and is reactor. What must be the minimum rating of each feeder circuit breaker?

(a) Cooling water tower efficiency

(b) Transient stability

(c) Equal area criterion

(d) Swing equation

What are the advantages of pumped storage plants? Discuss how water hammer and negative pressure can be prevented in hydro electric plants.

Compare the essential requirements for the favourable site selection for hydroelectric plants and thermal power plants. Also discuss the limitations of each.

Explain the interconnection of sequence network for (i) Line-to-line fault. (ii) Double line-to-ground fault

Explain the equal-area criterion for the stability of an alternator supplying infinite busbars via an inductive interconnector.

What are superheater and reheater?

On what factors does the power output of hydro-plant depends?

What is load duration curve? What information does it provides?

Name some of the categories of heat losses in a thermal plant.

Define critical clearing angle in equal area criterion?

Why ash handling plant necessary in thermal power plant?

What is two par tariff?

What is hydrograph? What information does it provides?

List the different methods to improve transient stability.

Define the sequence impedances.

Define the terms plant capacity factor and plant use factor and explain their importance in an electrical power system. Also explain the effect of the load factor on the cost of generation.

The power station supplies the peak loads of 25 MW, 20 MW and 30 MW to three localities. The annual load factor is 0.60 pu and the diversity of the load at the station is 1.65 pu. Calculate: (a) The maximum demand on the station. (b) The installed capacity. (c) The energy supplied in a year.

Derive the sequence impedance of transmission lines.

A set of unbalanced line currents in a three phase four wire system in as follows: $ I_a = -j6 A $, $ I_b = (-8+j5) A $ and $ I_c = 7 A $. Determine the zero sequence, positive sequence and negative sequence components of the current.

Prove that a line-to-ground fault at the terminals for a synchronous generator with solidly grounded neutral is more severe than a three-phase fault.

A 100 MVA, 11 KV, three-phase synchronous generator was subjected to different type of faults. The faults currents are as follows: LG fault - 4200 A; LL fault - 2600 A; LLL fault - 2000 A. The generator neutral is solidly grounded. Find the per unit values of the three sequence reactances of the generator.

Distinguish between steady state and transient stability of a power system and also discuss the factors on which these depends.

A 100 MVA, 2 pole, 60 Hz generator has a moment of inertia of $ 50 \times 10^3 \text{ kg-m}^2 $. Determine the following: (a) The energy stored in the rotor at the rated speed (b) The angular Momentum M and (c) The inertia constant H.

A transmission line of reactance 0.1 H and resistance 5 ohms is suddenly short circuited at $ t = 0 $ seconds at the bar end as shown in the figure [with an AC source $ V=100 \sin(100\pi t+15^{\circ}) $]. Write the expression for the short circuit current $ i(t) $ with a neat diagram. Find approximately the value of the first current maximum (maximum momentary current). Assume that the first current maximum occurs at the same time as the value of the first current maximum of the short circuit current.

Three 60 MVA ac generators, each having 15% reactance are connected via three 36 MVA reactors each of 10% reactance to a common busbar. The feeders are each connected to the junction of each alternator and is reactor. What must be the minimum rating of each feeder circuit breaker?

(a) Cooling water tower efficiency

(b) Transient stability

(c) Equal area criterion

(d) Swing equation

What are the advantages of pumped storage plants? Discuss how water hammer and negative pressure can be prevented in hydro electric plants.

Compare the essential requirements for the favourable site selection for hydroelectric plants and thermal power plants. Also discuss the limitations of each.

Explain the interconnection of sequence network for (i) Line-to-line fault. (ii) Double line-to-ground fault

Explain the equal-area criterion for the stability of an alternator supplying infinite busbars via an inductive interconnector.