A 200 MVA, 20 kV, 60 Hz, three-phase synchronous generator is connected through a 200 MVA, 20/138 kV, A-Y transformer to a 1 38 kV transmission line. The generator reactances to the machine's own base are; xs-1.40 The initial transient dc component in this machine averages 50 percent of the initial symmetrical ac component. The transformer's series reactance is 0.10 pu, and the resistance of both the generator and the transformer may be ignored. Assume that a symmetrical three-phase fault occurs on the 138 kV transmission line near to the point where it is the transformer. 1. What is the ac component of current in this generator the instant after the fault occurs? 2. What is the total current (ac plus dc) flowing in the generator right after the fault occurs?
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 200 MVA, 20 kV, 60 Hz, three-phase
synchronous generator is connected through
a 200 MVA, 20/138 kV, A-Y transformer to a
1 38 kV transmission line. The generator
reactances to the machine's own base
are; xs-1.40
The initial transient dc component in this
machine averages 50 percent of the initial
symmetrical ac component. The
transformer's series reactance is 0.10 pu,
and the resistance of both the generator and
the transformer may be ignored. Assume
that a symmetrical three-phase fault occurs
on the 138 kV transmission line near to the
point where it is the transformer.
1. What is the ac component of current in
this generator the instant after the
fault occurs?
2. What is the total current (ac plus dc)
flowing in the generator right after the
fault occurs?
3. What is the transient fault current If in
this fault?
4. What is the steady-state fault current If
in this fault?
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