Load Flow Studies in Power System?

In 3-phase ac power system active and reactive power flows from the generating stations to the load through different buses and branches. Active power (P) and Reactive power (Q) is supplied by the generators at generator buses. Active power is drawn by the loads from Load Buses. Reactive power is supplied or drawn from the load buses by shunt compensating elements such as shunt capacitors ( supply reactive power), and reactor elements (draws reactive power). The flow of active and reactive power in power system network is called 'Load Flow or Power Flow'. The voltages of the buses and their phase angles are affected by the power flow and vise-versa.

Load Flow studies in a power system provides systematic mathematical approach for determination of various bus voltages, their phase angles, active and reactive power flow through different branches, generators and loads under steady state conditions.

The main assumption for carrying load flow study is considering the system is in balanced condition. The mathematical formulation of the load flow problem results in a system of non-linear equations. These equations can be written as bus admittance matrix or bus impedance matrix. Bus Admittance matrix (Sparse Matrix - most of the elements in the matrix are zero) is widely used in digital computers for analysis because it requires less time to compute and requires less memory requirement.

Importance of Load Flow studies:

• Load flow studies are carried out to study the short circuit conditions for an inter connected network of power system.
• Load flow studies helps in planning the operation of power system under existing conditions, its improvements and future expansion.
• Load flow studies helps in determining the best size and favorable locations for placing power capacitors both for improving the power factor and also for raising the network voltage.
• Load flow studies helps in determining the best location and optimal capacity of the proposed generating stations, substations and new lines. Thus load flow studies are very important for planning existing systems as well as its future expansion.