Page 41 - Hybrid-Renewable Energy Systems in Microgrids

Microgrid architecture, control, and operation 25

Figure 2.1 Electrical equivalent circuit of parallel converter microgrid.

V
V = V + LpI + R I + w LI = M dci (2.1) Vsiq=Vmiq+LsipIsiq+RsiIsiq+
siq miq si siq sisiq si si sid iq
2
wsiLsiIsid=MiqVdci2
V
V = V + LpI + R I − w LI = M dci (2.2) Vsid=Vmid+LsipIsid+RsiIsid
sid
si
si
mid
sisid
sid
id
si siq
2
−wsiLsiIsiq=MidVdci2
Dynamic equation of the transmission line between two converters is given as,
V miq −V mjq = RI ijq + LI ijq + wL I ijd (2.3) Vmiq−Vmjq=R12Iijq+L12Iijq
12
12
12
si
+wsiL12Iijd
V −V = RI + LI − wL I (2.4) Vmid−Vmjd=R12Iijd+L12Iijd
mid mjd 12 ijd 12 ijd si 12 ijq
−wsiL12Iijq
A composite load has been assumed to be present as electrical load on microgrid,
which consists of a linear, anonlinear, and a constant power-type loads. The dynamics
of these loads are presented as follows:
Linear load equations,
V miq = R I + pLI + wL I (2.5) Vmiq=RLiILiq+pLLiILiq+wsi
Li Liq
LiLiq
si
LiLid
LLiILid
V mid = R I + pLI − wL I (2.6) Vmid=RLiILid+pLLiILid−wsi
si
Li Lid
LiLid
LiLiq
LLiILiq
Nonlinear load equation,
2 PV −Q V
I = inon miq inon mid (2.7) Inonq=23PinonVmiq−Qinon
nonq
2
2
3 V mid +V miq VmidVmid2+Vmiq2