Synchronous Machines - Structure

Transcription

1 Synchronou Machine - Structure

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3 Synchronou Machine - Structure rotate at contant peed. primary energy converion device of the word electric power ytem. both generator and motor operation can draw either a lagging or a leading reactive current from the upply ytem. Non-alient pole generator high peed (2-4 pole) large power ( MVA) team and nuclear power plant Salient pole generator mall and mid-ize power ( MVA) mall motor for electrical clock and other dometic device mid ize generator for emergency power upply mid ize motor for pump and hip propulion large ize generator in hydro-electric power plant

4 Synchronou Generator No-load excitation voltage frequency depend on the peed f = np 120 n = 120 f p E f NK f = 4.44 Φf w Ef f nφ open circuit characteritic magnetization characteritic

5 Synchronou Generator - loaded the tator current will etablih a rotating field in the air-gap armature reaction flux Φ a reultant air-gap flux Φ = Φ + Φ r f a

6 Synchronou Machine The Infinite Bu

7 Synchronou Machine Paralleling with The Infinite Bu ame voltage frequency phae equence phae ynchronizing lamp 1. Same f and phae equence 2. Same V and phae equence 1. Same V and f

8 Synchronou Motor - Starting high inertia of the rotor prohibit direct connection into upply net variable-frequency upply tart a an induction motor

9 Synchronou Machine Per Phae Equivalent Circuit Model armature flux, armature reaction flux, armature leakage flux Φa = Φar + Φal Φ = Φ + Φ r Er = Ear + Ef E = j I ar f ( If ) ar ( Ia ) ar a E = I j + E f a ar r magnetizing reactance ar, (reactance of armature) ynchronou reactance = ar + al ynchronou impedance Z =R a + j

10 Synchronou Machine Equivalent Circuit Model Norton equivalent circuit I E f f ar = If 2 N = ni re f n = 3 N e

11 Equivalent Circuit Model Determination of the Synchronou Reactance open circuit tet ynchronou peed tator open-circuited meaure V t (I f ) open-circuit characteritic air-gap line hort circuit tet ynchronou peed tator hort-circuited meaure I a (I f ) hort-circuit characteritic traight line flux remain at low level I a lag the E f by almot 90 becaue R a

12 Equivalent Circuit Model Determination of the Synchronou Reactance unaturated value from the air-gap line E Z R j (unat) da da = = a + (unat) (unat) Iba Iba E

13 Equivalent Circuit Model Determination of the Synchronou Reactance Saturated E = V + I ( R + j ) V r t a a al t at infinite bu operation the aturation level i defined by terminal voltage operation point c if the field current i changed the excitation voltage will change along modified air-gap line OC Eca Z(at) = = Ra + j I ba (at) (at) E I ca ba

14 Synchronou Machine Phaor Diagram terminal voltage taken a the reference vector generator power angle poitive E = V + I R + I j = E δ f t a a a motor power angle negative V = E + I R + I j t f a a a f E = V 0 I R I j f t a a a = E δ f convention: generating current flow out of the machine

15 Synchronou Machine Power and Torque V t Vt 0 f = E = E δ f Z = Ra + j = Z θ S * t a = V I I * * * * Ef Vt Ef Vt a = = * * Z Z Z Ef δ = Z θ θ Ef Vt = θ δ θ Z Z Z V t 0 convention: lagging reactive power poitive

16 Synchronou Machine Power and Torque complex power Vt Ef Vt S = θ δ θ Z Z 2 real power Vt Ef Vt P = co( θ δ) coθ Z Z 2 reactive power Vt Ef Vt Q = in( θ δ) inθ Z Z 2

17 R a neglected real power Synchronou Machine Power and Torque 3 V E P φ δ inδ t f 3 = in = Pmax reactive power Q 3φ 3Vt Ef 3V = coδ t 2 torque T = P3 φ δ δ ω = 3 Vt Ef in ω = Tmax in N m yn yn

18 Synchronou Machine Complex Power Locu 3 V E P φ δ inδ t f 3 = in = Pmax Q 3φ 3Vt Ef 3V = coδ t 2

19 Synchronou Machine Capability Curve armature heating, length of OM field heating, length of YM teady-tate tability δ

20 Synchronou Machine Power Factor Control machine connected to an infinite bu P= 3VtIacoφ for contant power operation Ia co φ = cont. reactive current can be controlled by field current j I = V E a t f alo P = 3 VE t f in δ E f inδ = cont

21 Synchronou Machine Independent Generator purely inductive load (I c i hort-circuit current) V = E I I t f a a V = I I c a = ( I I ) c a purely reitive load E I = = R R = I R t a L f c 2 L L + 2 quarter ellipe 2 Vt 2 Ia c 2 2 Ic ( I ) + = 1 control curve contant terminal voltage

22 Salient Pole Synchronou Machine the field mmf and flux are along the d-axi tator current i in phae with the excitation voltage armature mmf and flux are along the q-axi tator current i lagging the excitation voltage by 90 degree armature mmf and flux act along the d-axi, directly oppoing the field the ame magnitude of the armature mmf produce more flux in d- direction than that in q-direction magnetizing reactance i not unique in a alient pole machine

23 Salient Pole Synchronou Machine the armature quantitie can be reolved into two component one acting along the d-axi (F d, I d ), and the other acting along the q-axi (F q, I q ), thee component produce fluxe along the repective axe (Φ ad, Φ aq ), d-axi armature reactance d q-axi armature reactance q leakage reactance al ynchronou reactance d = ad + al q = aq + al

24 Salient Pole Synchronou Machine Phaor Diagram the component current (I d, I q ), produce component voltage drop (ji d d, ji q q ) E = V + I R + I j + I j Ia = I + Iq f t a a d d q q generator phaor diagram (I a lagging) d ψ internal power factor angle φ terminal power factor angle δ torque angle R a neglected

25 Salient Pole Synchronou Machine Phaor Diagram motoring phaor diagram (I a lagging) ψ internal power factor angle φ terminal power factor angle δ torque angle V = E + I j + I j t f d d q q ψ = φ ± δ I I I d = ainψ = ain( φ ± δ ) tanδ = V I a ± q I t a q coφ inφ I = I coψ = I co( φ ± δ ) q a a E = V coδ ± I f t d d

26 Power Tranfer S * t a = V I = V δ ( I j I ) t q d * = V δ ( I + j I ) t q d I d = E f V t d coδ I q = V t inδ q

27 Power Tranfer 2 2 t t f t V V E V S= inδ δ + 90 δ coδ 90 δ = P+ jq q d d d 2 Vt Ef Vt ( d q) P= inδ + in 2δ = Pf + P 2 d q r Q d 2 2 Vt Ef 2 in δ co = coδ Vt + q d δ if d = q, then P = V E t d f inδ Q Vt Ef = coδ d V t d 2

28 Power Tranfer - Torque d 2 Vt Ef Vt ( d q) P= inδ + in 2δ = Pf + P 2 d q r

29 Determination of d and q lip tet rotor i driven at a mall lip field winding open-circuited tator i connected to a balanced three phae upply tator encounter varying reluctance path amplitude of the tator current varie d = i V t min 2 q = i V t max 2

30 Speed Control of Synchronou Motor open-loop frequency control

31 frequency control Speed Control of Synchronou Motor P = Tω = ω = m m 4π f p 3VE t f inδ = 2π fl field current kept contant Ef = K f 1 V T = K t inδ f voltage i changed with the frequency

32 Speed Control of Synchronou Motor elf-controlled ynchronou motor rotor poition information i ued to decreae the tator frequency open-loop / cloed-loop control

33 Application ac generator contant peed operation high efficiency motor-generator et, air compreor, centrifugal pump, blower, cruher, mill power factor control, ynchronou reactor, -condener