The load flow, system stability and short circuit analysis are three main area of transmission and network study and design.
A load flow analysis allows identification of real and reactive power flows, voltage profiles, power factor and any overloads in the network. Once the network parameters have been entered into the computer database the analysis allows the engineer to investigate the performance of the network under a variety of outage conditions.
The problem of stability in a network concerns energy balance and the ability to generate sufficient restoring forces to counter system disturbances. Minor disturbances to the system result in a mutual interchange of power between the machines in the system acting to keep them in step with each other and to maintain a single universal frequency. A state of equilibrium is retained between the total mechanical power/energy-input and the electrical power/energy-output bynatural adjustment of system voltage levels and the common system frequency.
A short circuit analysis allows the engineer to determine the make and break fault levels in the system for both symmetrical and asymmetrical, low or high impedance faults. This in turn allows the correct determination of system component ratings; for example the fault rating capability of circuit breakers. A full analysis will allow investigation of protection requirements and any changes to the system that might be necessary in order to reduce fault levels.