What is the need for load flow analysis.

What is the need for load flow analysis.
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Answer :

The load flow study of a power system is essential to decide  the best operation of existing system and for planning the future  expansion of the system. It is also essential for designing a new  power system.
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Related questions

A power system has 100 buses including 10 generator buses. For the load flow analysis using Newton-Raphson method in polar coordinates, the size of the Jacobian is a) 189x189 b) 100x100 c) 90x90 d) 180x180

Description : A power system has 100 buses including 10 generator buses. For the load flow analysis using Newton-Raphson method in polar coordinates, the size of the Jacobian is a) 189x189 b) 100x100 c) 90x90 d) 180x180

Last Answer : a) 189x189

In a load flow analysis of a power system, the load connected at a bus is represented as a) Constant current drawn from the bus b) Constant impedance connected at the bus c) Voltage and frequency dependent sources at the boss d) Constant real and reactive power drawn from the bus

Description : In a load flow analysis of a power system, the load connected at a bus is represented as a) Constant current drawn from the bus b) Constant impedance connected at the bus c) Voltage and frequency dependent sources at the boss d) Constant real and reactive power drawn from the bus

Last Answer : d) Constant real and reactive power drawn from the bus

What is the need for slack bus in power flow analysis.

Description : What is the need for slack bus in power flow analysis.

Last Answer : The slack/swing bus is needed to account for transmission line losses. In a power system the total power generated will be equal to sum of power consumed by loads and losses. In a power ... power are not specified for slack bus. They are estimated through the solution of load flow equations.

What technique is used to solve load flow problems using Z-bus (Bus impedance matrix)?

Description : What technique is used to solve load flow problems using Z-bus (Bus impedance matrix)?

Last Answer : The formulation of load flow problem using Zbus employs Diakoptics techniques which is actually the piecewise solution of the power system problem by using tearing off technique.

Discuss the effect of acceleration factor in the load flow solution algorithm.

Description : Discuss the effect of acceleration factor in the load flow solution algorithm.

Last Answer : An acceleration factor is a value that can be used to speed up the convergence and reduce the number of required alteration in a Gauss Seidel method of power flow analysis .Very high or very ... trial and error load flow analysis. A generally recommended value of the acceleration factor is 1.6.

What is the information that are obtained from a load flow study.

Description : What is the information that are obtained from a load flow study.

Last Answer : • The magnitude and phase of bus voltages, real and reactive power flowing in each line and the line losses. • The load flow solution also gives the initial conditions of the system when the transient behavior of the system is to be studied.

Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion: Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions. Reason: Accuracy depends on the power mismatch vector tolerance. a) Both [a] and [r] are true and [r] is the correct reason for [a]. b) Both [a] and [r] are true and [r] is not the correct reason for [a]. c) [a] is false and [r] is true.

Description : Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion: Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions. Reason: Accuracy ... the correct reason for [a]. c) [a] is false and [r] is true.

Last Answer : c) [a] is false and [r] is true

In a load flow problem solved by newton-Raphson method with polar coordinates, the size of the Jactobian is 100 × 100. If there are 20 PV buses in addition to PQ buses and a slack bus, the total number of buses in the system is_____

Description : In a load flow problem solved by newton-Raphson method with polar coordinates, the size of the Jactobian is 100 × 100. If there are 20 PV buses in addition to PQ buses and a slack bus, the total number of buses in the system is_____

Last Answer : 61

or accurate load flow calculations on large power systems, the best method is a) N-R method b) G-S method c) Decoupled method d) all of the above

Description : or accurate load flow calculations on large power systems, the best method is a) N-R method b) G-S method c) Decoupled method d) all of the above

Last Answer : a) N-R method

In load flow studies of a power system, a voltage control bus is specified by a) Real power and reactive power b) Reactive power and voltage magnitude c) Voltage and voltage phase angle d) Real power and voltage magnitude

Description : In load flow studies of a power system, a voltage control bus is specified by a) Real power and reactive power b) Reactive power and voltage magnitude c) Voltage and voltage phase angle d) Real power and voltage magnitude

Last Answer : d) Real power and voltage magnitude

Which of the following matrix is used for load flow studies? a) null matrix b) Unit matrix c) Z bus matrix d) Y bus matrix

Description : Which of the following matrix is used for load flow studies? a) null matrix b) Unit matrix c) Z bus matrix d) Y bus matrix

Last Answer : d) Y bus matrix

For load flow studies, what are the quantities specified at load bus are. a) P and V b) P and Q c) V and δ d) δ and Q

Description : For load flow studies, what are the quantities specified at load bus are. a) P and V b) P and Q c) V and δ d) δ and Q

Last Answer : b) P and Q

Define voltage-controlled bus and load bus.

Description : Define voltage-controlled bus and load bus.

Last Answer : LOAD BUS A bus is called PQ bus or load bus when real and reactive components of power are specified for the bus. In a load bus the voltage is allowed to vary within permissible limits ... constant using automatic voltage regulator, we can specify constant PGi and | Vi | for these buses.

When will the generator bus is treated as load bus.

Description : When will the generator bus is treated as load bus.

Last Answer : If the reactive power of a generator bus violates the specified limits then the generator bus is treated as load bus.

Specified quantities of load bus are a) P and Q b) V and δ c) P and δ d) Q and V

Description : Specified quantities of load bus are a) P and Q b) V and δ c) P and δ d) Q and V

Last Answer : a) P and Q

In power system, if a voltage controlled bus is treated as a load bus then which one of the following limits would be violated? a) Voltage b) Active power c) reactive power d) Phase angle

Description : In power system, if a voltage controlled bus is treated as a load bus then which one of the following limits would be violated? a) Voltage b) Active power c) reactive power d) Phase angle

Last Answer : a) Voltage

In power system, the maximum number of buses are a) Generator buses b) Load buses c) Slack buses d) P-V buses

Description : In power system, the maximum number of buses are a) Generator buses b) Load buses c) Slack buses d) P-V buses

Last Answer : b) Load buses

Explain Flat Voltage start.

Description : Explain Flat Voltage start.

Last Answer : In iterative methods of load flow solution, the initial voltages of all buses except slack bus are assumed as 1+j0 p.u. This is referred to as flat voltage start.

Mention the various types of buses in power system with specified quantities for each bus.

Description : Mention the various types of buses in power system with specified quantities for each bus.

Last Answer : • Load bus or PQ-bus (P and Q are specified- Voltage magnitude and angle are to be obtained) • Generator bus or voltage controlled bus or PV bus (P and V are specified- Voltage angle and Q are to be obtained)

What are the advantages of FDLF method.

Description : What are the advantages of FDLF method.

Last Answer : FDLF method is faster, simple to program, more reliable and requires less memory than NR load flow method. FDLF method requires more iteration than N-R method, but requires less time per iteration.

What is jacobian matrix?

Description : What is jacobian matrix?

Last Answer : The Jacobian matrix gives the linearized relationship between small changes in voltage angle or voltage magnitude with a small changes in real and reactive power.

What are the disadvantages of NR method.

Description : What are the disadvantages of NR method.

Last Answer : • The programming is more complex. • The memory requirement is more. • Computational time per iteration is higher due to large number of calculations per iteration.

Mention any three advantages of N-R method over G-S method.

Description : Mention any three advantages of N-R method over G-S method.

Last Answer : • The N-R method has quadratic convergence characteristic and so convergence faster than G-S method. • The number of iterations for convergence is independent of the size of the system in N-R method. • In N-R method the convergence is not affected by the choice of slack bus.

What are the four quantities that are associated with each bus in a system?

Description : What are the four quantities that are associated with each bus in a system?

Last Answer : • Real Power • Reactive Power • Voltage magnitude • Phase angle of voltage

A 1000 × 1000 bus admittance matrix for an electric power system has 8000 non-zero elements. The minimum number of branches (transmission lines and transformers) in this system are _____ (up to 2 decimal places)

Description : A 1000 × 1000 bus admittance matrix for an electric power system has 8000 non-zero elements. The minimum number of branches (transmission lines and transformers) in this system are _____ (up to 2 decimal places)

Last Answer : Ans: 3500.00

In a 4 bus,4×4 Y bus matrix the number of non zero elements are 12. Find the number of transmission lines? a) 8 b) 4 c) 2 d) 5

Description : In a 4 bus,4×4 Y bus matrix the number of non zero elements are 12. Find the number of transmission lines? a) 8 b) 4 c) 2 d) 5

Last Answer : b) 4

Which of the following quantities are to be calculated for generator bus a) P and V b) V and δ c) δ and Q d) Q and P

Description : Which of the following quantities are to be calculated for generator bus a) P and V b) V and δ c) δ and Q d) Q and P

Last Answer : c) δ and Q

The voltage of a particular bus can be controlled by controlling the a) Active power of the bus b) Reactive power of the bus c) Phase angle d) All of the above

Description : The voltage of a particular bus can be controlled by controlling the a) Active power of the bus b) Reactive power of the bus c) Phase angle d) All of the above

Last Answer : b) Reactive power of the bus

A 4 bus power system consists of 4 transmission lines, then find the sparsity of Y bus matrix? a) 0.75 b) 0.25 c) 0.4 d) 0.5

Description : A 4 bus power system consists of 4 transmission lines, then find the sparsity of Y bus matrix? a) 0.75 b) 0.25 c) 0.4 d) 0.5

Last Answer : b) 0.25

The value of off diagonal elements is a) sum of admittances connected at bus j b) which is connected between bus i and bus j with positive sign c) which is connected between bus i and bus j with negative sign d) sum of admittances connected at bus i

Description : The value of off diagonal elements is a) sum of admittances connected at bus j b) which is connected between bus i and bus j with positive sign c) which is connected between bus i and bus j with negative sign d) sum of admittances connected at bus i

Last Answer : c) which is connected between bus i and bus j with negative sign

If sparsity of a 5 bus transmission line is 0.4. Find the number of transmission lines? a) 6 b) 5 c) 4 d) 3

Description : If sparsity of a 5 bus transmission line is 0.4. Find the number of transmission lines? a) 6 b) 5 c) 4 d) 3

Last Answer : b) 5

A network containing 50 buses in which 10 are the voltage control buses, 6 are the generator buses. Find the size of the Jacobian matrix. a) 84*84 b) 83*83 c) 34*34 d) 33*33

Description : A network containing 50 buses in which 10 are the voltage control buses, 6 are the generator buses. Find the size of the Jacobian matrix. a) 84*84 b) 83*83 c) 34*34 d) 33*33

Last Answer : b) 83*83

um of the elements of row i equal to shunt admittances connected to bus i. If this summation is zero, indicates there is no a) shunt admittance b) mutual coupling c) both 1 and 2 d) none of the above

Description : um of the elements of row i equal to shunt admittances connected to bus i. If this summation is zero, indicates there is no a) shunt admittance b) mutual coupling c) both 1 and 2 d) none of the above

Last Answer : c) both 1 and 2

Advantage of Gauss-Seidel method is a) applicable for large power system network b) calculation time for each iteration is less c) number of iterations are less d) all of the above

Description : Advantage of Gauss-Seidel method is a) applicable for large power system network b) calculation time for each iteration is less c) number of iterations are less d) all of the above

Last Answer : b) calculation time for each iteration is less

For n bus power system size of Y bus matrix is a) n*n b) (n-1)*(n-1) c) (n-1)*(n-2) d) (n-2)*(n-2)

Description : For n bus power system size of Y bus matrix is a) n*n b) (n-1)*(n-1) c) (n-1)*(n-2) d) (n-2)*(n-2)

Last Answer : a) n*n

Normally Z bus matrix is a a) null matrix b) sparse matrix c) full matrix d) unit matrix

Description : Normally Z bus matrix is a a) null matrix b) sparse matrix c) full matrix d) unit matrix

Last Answer : full matrix

In load flow analysis, the load connected at a bus is represented as?

Description : In load flow analysis, the load connected at a bus is represented as?

Last Answer : constant real and reactive powers drawn from bus

n project financing ,sensitivity analysis is applied because a) almost all the cash flow methods involve uncertainty b) of the need to assess how sensitive the project to changes in input parameters c) what if one or more factors are different from what is predicted d) all the above situation

Description : n project financing ,sensitivity analysis is applied because a) almost all the cash flow methods involve uncertainty b) of the need to assess how sensitive the project to changes in input parameters c) what if one or more factors are different from what is predicted d) all the above situation

Last Answer : d) all the above situation

Wind load analysis can be performed following methods. a) experiments wind pressure coefficient b) shape factors c) wind-induced vibration coefficient d) all of above

Description : Wind load analysis can be performed following methods. a) experiments wind pressure coefficient b) shape factors c) wind-induced vibration coefficient d) all of above

Last Answer : all of above

In the virtual work method of plastic analysis of steel structures, the virtual quantity is (a) Slope (b) Moment (c) Load (d) Displacement

Description : In the virtual work method of plastic analysis of steel structures, the virtual quantity is (a) Slope (b) Moment (c) Load (d) Displacement

Last Answer : (d) Displacement

A regional boo onal bookstore chai re chain is ab n is about to build a distribution cen ion center that is centrally located for its eight retail outlets. It will most likely employ likely employ which of the following which of the following tools of analysis? a. assembly assembly line balancing b. balancing b. load- distance analysis c. center-of-gravity model d. linear programming

Description : A regional boo onal bookstore chai re chain is ab n is about to build a distribution cen ion center that is centrally located for its eight retail outlets. It will most likely employ likely ... balancing b. balancing b. load- distance analysis c. center-of-gravity model d. linear programming

Last Answer : c. center-of-gravity model

Give the circuit analysis of current source inverter with resistive load.

Description : Give the circuit analysis of current source inverter with resistive load. What are the main difference between voltage source inverter and current source inverter?

Last Answer : Current source inverter (CSI): In current source inverter, the output current is independent of load. The input current of current source inverter is constant. Current source converter converts DC input current to ... are connected in parallel. In CSI diodes are connected in series.

How do I solve this discounted cash flow analysis?

Description : How do I solve this discounted cash flow analysis?

Last Answer : answer:Saw? I’m confused. You only mentioned one saw, and that is the one used to make desks for the next 10 years. So, you use the one you have. What am I missing, Jellies?

Choose the right sequence for Production Flow Analysis a.PFA Chart - Data Collection - Sortation of process plans b.Data collection - PFA chart - Sortation of process plans c.Sortation of process plans - Data collection - PFA chart d.Data collection - Sortation of process plans - PFA chart

Description : Choose the right sequence for Production Flow Analysis a.PFA Chart - Data Collection - Sortation of process plans b.Data collection - PFA chart - Sortation of process plans c.Sortation of process plans - Data collection - PFA chart d.Data collection - Sortation of process plans - PFA chart

Last Answer : d.Data collection - Sortation of process plans - PFA chart

Which of the following is not the method of part family formation a.Visual inspection method b.Automatic product sorting c.Parts classification & coding d.Production flow analysis

Description : Which of the following is not the method of part family formation a.Visual inspection method b.Automatic product sorting c.Parts classification & coding d.Production flow analysis

Last Answer : b.Automatic product sorting

The following is basically a material flow simplification technique a.A simple and visual method of cell design b.Family formation by classification and codification c.Cell formation using Production Flow Analysis d.All of the above

Description : The following is basically a material flow simplification technique a.A simple and visual method of cell design b.Family formation by classification and codification c.Cell formation using Production Flow Analysis d.All of the above

Last Answer : c.Cell formation using Production Flow Analysis

Which of the following technique of grouping does not consider the design and shape aspect? a.A simple and visual method of cell design b.Family formation by classification and codification c.Cell formation using Production Flow Analysis d.All of the above

Description : Which of the following technique of grouping does not consider the design and shape aspect? a.A simple and visual method of cell design b.Family formation by classification and codification c.Cell formation using Production Flow Analysis d.All of the above

Last Answer : c.Cell formation using Production Flow Analysis

In cell formation using production flow analysis, the following process will be left out of theanalysis a.Grinding b.Milling c.Drilling d.Gear cutting

Description : In cell formation using production flow analysis, the following process will be left out of theanalysis a.Grinding b.Milling c.Drilling d.Gear cutting

Last Answer : d.Gear cutting

Why power flow analysis is made?

Description : Why power flow analysis is made?

Last Answer : Power flow analysis is performed to calculate the magnitude and phase angle of voltages at the buses and also the active power and reactive voltamperes flow for the given terminal or bus conditions. The variables ... | b. Phase angle of voltage δ c. Active power, P d. Reactive voltamperes, Q