FAQ's about Load Flow Analysis Part 1

• What is Power Flow ?

Power flow in a network is determined by the voltage at each bus of the network and the impedance of the lines between buses. Load flow/Power flow solution is the determination of current, voltage, active and reactive power at various points in a power system operating under normal steady state/static conditions.

• What are the important parameters of Load Flow Analysis?

1) Magnitude of Voltage.

2) Phase angle

3) Active Power (P)

4) Reactive Power (Q)

In steady state conditions :-

Magnitude of voltage (mod V) is directly proportional to Q and Angle delta is directly proportional to P.

• What are the outcomes of Load Flow Study ?

Load flow of a power system is essential to decide the best operation of existing system and for planning the future expansion of the system. Also essential for designing a new system so that power flows are within equipment ratings. Voltages are within acceptable operating limits.

• What are the steps to conduct Load Flow ?

a) Representation of the system by Single Line Diagram (SLD).

b) Determining the impedance diagram using the information in SLD.

c) Formulation of network equation.

d) Solution of network equations.

• What are the type of buses in Load Flow ?

a) Generator Bus/Voltage Controlled Bus

b) Load Bus/PQ Bus

c) Slack/Swing Bus

• Define Voltage Controlled Bus ?

In case of voltage controlled bus magnitude of voltage and real power are specified. Magnitude of voltage cannot be changed.

• What is PQ Bus ?

A bus is called PQ or Load bus when real and reactive components of power are specified for the bus. In load bus the voltage is allowed to vary with in permissible value.

• What is Swing Bus ?

Voltage magnitude and phase angle are specified. Swing bus is the reference bus for load flow analysis and it is required for accounting line losses.

• What are the iterative methods used for Load Flow Problems ?

a) Guass Seidal (GS) method.

b) Newton Raphson(NR) Method

c) Fast decoupled method.