Power Systems

Fundamentals of;• Power generation,• Transmission lines,• Distribution lines

Basic operations required for the power systems

Load Flow Fault Studies

Protection Earthing Stability

Insulation coordination Economic dispatch

Power QualityElectromagnetic Compabilty, EMC

Load Forecasting

Basic Structure of the Electric System

Generating Stations

Fossil Fuel Hydroelectric Nuclear Geothermal Renewable

Photovoltaics Solar Thermal Wind Bio-gas

Transmission Lines

High Voltage 69 kV–500 kV Power Capacity 50–1,000 MW Carry power long distances Low energy losses, P=V²/RLarge structures

Distribution Lines

Primary; 12 – 34 kV AC Secondary: 480 V – 120 V AC Power capacity: 10 – 40 MW Shorter distances, higher losses Smaller overhead structures Underground

Power Analysis

In AC: 1 phase:

u=Um.cos(wt)i=Imcos(wt-θ)

p=u.i=UmImcos(wt)cos(wt-θ)

(instantaneous value of the power)

In DC:P=U.I

Power Analysis

p=u.i= Umcos(wt) Imcos(wt-θ)

Power Analysis

p=u.i=UmImcos(wt)cos(wt-θ)

p=UI cosθ (1+cos(2wt))+UI sinθ sin(2wt)

active component reactive component

P=UI cosθ (active power) {W} Q=UI sinθ (reactive power) {VAr}

Cosθ= (Power factor)

Power Analysis

S=P+jQ (Complex Power) S²=P²+Q² (Apparent power) {VA}

Power Analysis

3 phase systems:Up=Ua=Ub=Uc

Ip=Ia=Ib=Ic

Power Analysis

Y ConnectionIl=Ip

Ul= Up

P=3UpIpcosφQ=3UpIpsin φS=3UpIp

Power Analysis

Delta ConnectionIp=Il√3 Ul=Up,

P=√3UlIlcosφ

(Generally)Up= 220 V

Ul= 220.√3 = 380 V

Thank you for listening…

Caner Göksel Sonuzun