Simulation of three-phase short-circuit at the terminals of synchronous machine
Three-phase sudden short-circuit at the terminals of a synchronous machine under open circuit condition is simulated. The standard parameters are calculated by using the known parameters, and substituted into the analytical expression for computing short-circuit current. The curve of the relationship between the maximal armature momentary current and the rotor angle is plot. It is concluded that the armature momentary current is maximal when short-circuit occurring at the time of the terminal voltage wave is going through zero. Furthermore, a simulation model in SIMULINK environment is constructed, thus the oscillograms of the armature short-circuit currents in the three phases and the field short-circuit current are plot.
An analysis of the results from the computation of transients in synchronous generators using frequency domain methods
A method using fast Fourier transforms to simulate sudden short circuits on two machines and line switching tests on one of them is presented. The results arising from the use of test data, equivalent circuit data, and finite-element calculated data are compared with measurements. The comparison is used to clarify problems encountered in the use of standstill frequency-response data and to highlight errors resulting from the derivation of equivalent circuits. The results also give some insight into the best way to model synchronous machines in transients. >
Flow in a branching open channel: a review
Branching channel flow refers to any side water withdrawals from rivers or main channels. Branching channels have wide application in many practical projects, such as irrigation and drainage network systems, water and waste water treatment plants, and many water resources projects. In the last decades, extensive theoretical and experimental investigations of the branching open channels have been carried out to understand the characteristics of this branching flow, varying from case studies to theoretical and experimental investigations. The objectives of this paper are to review and summarise the relevant literatures regarding branching channel flow. These literatures were reviewed based on flow characteristics, physical characteristics, and modeling of the branching flow. Investigations of the flow into branching channel show that the branching discharge depends on many interlinked parameters. It increases with the decreasing of the main channel flow velocity and Froude number at the upstream of the branch channel junction. Also it increases with the increasing of the branch channel bed slope. In subcritical flow, water depth in the branch channel is always lower than the main channel water depth. The flow diversion to the branch channel leads to an increase of water depth at the downstream of the main channel. From the review, it is important to highlight that most of the study concentrated on flow characteristics in a right angle branch channel with a rigid boundary. Investigations on different branching angles with movable bed have still to be explored.