List of Symbols - Wind Energy Systems for Electric Power Generation - page 173

Q reactive power, VA

R winding resistance, Ω

Q reactive power

s slip, in per unit value of synchronous speed

S apparent power

T machine torque, N · m

U voltage, V

X reactance, Ω

Y admittance, Ω

Z = R + j · X notation of a complex quantity (impedance as example)

= √ R 2 + X 2

Z = | Z | absolute value of a complex quantity (impedance as

example)

Z impedance, Ω

z p number of pole pairs

ϑ load angle (synchronous machines)

λ power factor

ϕ phase angle

Φ magnetic flux, Wb

ψ short-circuit impedance angle

Ψ flux linkage, Wb

σ leakage factor

pulsation, s − 1 ω

angular speed, s − 1 Ω

η efficiency

temperature, ◦ C

θ

τ time constant, s

Subscripts
Machine component

1, 2 primary, secondary

a armature

e excitation

f field winding

ph per-phase value

r rotor

s stator

syn synchronous

w winding

U, V, W phase designations

Machine category
E

exciter

G generator

M motor