GANDHINAGAR INSTITUTE OF TECHNOLOGY Electrical Power System Presentation On Representation of Power System Components Electrical Power System (2150908) Electrical Engineering Submitted by: Jay Kared (130120109016) Rijay Doshi (130120109007) Aditya Mehra (130120109001)

PRESENTATION ON : Power System Components Per Unit System Complex Power

ELECTRICAL POWER SYSTEM Representation of power system 1) Components: Representation of transformer, Per unit impedance , Diagram of power system. 2) Complex power : the steady state model of synchronous machine power factor power control.

Power System Representation using One Line Diagrams • One Line Diagram or Single Line Diagram

Line Diagram of full Power System

The following assumptions are made while making impedance diagram of power system:- Single phase transformers are assume as ideal transformers with their impedances indicated at one side. The generators are represented as voltage sources with series resistance and inductive reactance. Loads are represents by resistance and inductance in series. The transmission lines are represented by pi model.

Per Unit System It is usual to represent voltage , power , current and impedance in per unit of base or reference values .The per unit value of any quantity is defined as : Actual value in any units Base value in same units

Per-Unit Quantities Per unit quantities are quantities that have been normalized to a base quantity. In general Choice of the base value Zbase is normally a rated value which is often one of the normal full-load operations of power component in a power network. Let us look at two of the most common per unit formula which are widely used when per unit calculations are involved. (i) Base impedance (Zbase) For a given single-line (one-line) diagram of a power network, all component parameters are expressed in 3- quantity whether it is the rating (capacity) expressed as MVA or voltage as kV. Let begin with 3- base quantity of

(ii) Changing base impedance (Znew] Sometimes the parameters for two elements in the same circuit (network) are quoted in per-unit on a different base. The changing base impedance is given as,

Complex Power

Complex Power, cont’d

Complex Power, cont’d Instantaneous power into resistive component Instantaneous power into electric and magnetic fields

Complex Power (Note: S is a complex number but not a phasor.)

Complex Power, cont’d Power Triangle |S| Q f P

Complex Power, cont’d negative since leading pf Load consumes -62 kVAr, i.e. load supplies +62 kVAr  capacitive load

References Modern Power Systems by Nagarath Kothari Electrical Power Systems by V.K Mehta Power System Engineering by C.L Wadhwa

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