Q6: A five-bus network has generators at buses 1 and 3 rated 270 and 225 MVA, respectively. The generator sub-transient reactances plus the reactances of the transformers connecting them to the buses are each 0.3 pu on the generator rating as base. The turns ratios of the transformers are such that the voltage base in each generator circuit is equal to the voltage rating of the generator. Line impedances in pu on a 100 MVA system base are shown in Fig. below. All resistances are neglected. Using the bus impedance matrix for the network which includes the generator and transformer reactances, find the sub-transient current in a three phase fault at bus 4 and the current coming to the faulted bus over each line. Prefault current is to be neglected and all voltages are assumed to be 1 pu before the fault occurs. (2) j0.126 1.0/0° j0.168 ll 1.0/0 ll j0.1333 ll j0.1111 ll 5 j0.126 j0.210 ell j0.252 4 j0.336 hellte
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.
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