A "round rotor 3-phase star connected alternator", some parameters of which are given below, operates in parallel with the grid and feeds the following current to the grid over the line. Meanwhile, the power factor is cos_fi=1. Then, without changing the driving torque applied to the generator from the shaft, the excitation current=If is changed as given below. In this new situation, which of the following will be the power factor (G_cos_fi) of the generator? (The machine will be assumed to be magnetically linear and no saturation. Also, the internal resistance of the armature will be neglected.) V1L= 500 Volts Xs = 10 Ohms I1L= 5 A
Load flow analysis
Load flow analysis is a study or numerical calculation of the power flow of power in steady-state conditions in any electrical system. It is used to determine the flow of power (real and reactive), voltage, or current in a system under any load conditions.
Nodal Matrix
The nodal matrix or simply known as admittance matrix, generally in engineering term it is called Y Matrix or Y bus, since it involve matrices so it is also referred as a n into n order matrix that represents a power system with n number of buses. It shows the buses' nodal admittance in a power system. The Y matrix is rather sparse in actual systems with thousands of buses. In the power system the transmission cables connect each bus to only a few other buses. Also the important data that one needs for have a power flow study is the Y Matrix.
Types of Buses
A bus is a type of system of communication that transfers data between the components inside a computer or between two or more computers. With multiple hardware connections, the earlier buses were parallel electrical wires but the term "bus" is now used for any type of physical arrangement which provides the same type of logical functions similar to the parallel electrical bus. Both parallel and bit connections are used by modern buses. They can be wired either electrical parallel or daisy chain topology or are connected by hubs which are switched same as in the case of Universal Serial Bus or USB.
A "round rotor 3-phase star connected alternator", some parameters of which are given below, operates in parallel with the grid and feeds the following current to the grid over the line. Meanwhile, the power factor is cos_fi=1.
Then, without changing the driving torque applied to the generator from the shaft, the excitation current=If is changed as given below. In this new situation, which of the following will be the power factor (G_cos_fi) of the generator? (The machine will be assumed to be magnetically linear and no saturation. Also, the internal resistance of the armature will be neglected.)
V1L= 500 Volts
Xs = 10 Ohms
I1L= 5 A
If change = 10% increase
a) 0.704 forward
b 0.499 back
c) 0.985 forward
d) 0.866 back
e) 0.173 back
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