Page 133 - Hybrid-Renewable Energy Systems in Microgrids

Study of control strategies of power electronics during faults in microgrids 117

Figure 7.3 Control structure of a grid-connected VSI with negative-sequence current
control loop.

1 ( + kQ ) ∗ 1 ( − kP ) ∗
∗
+
+
−
qQ + 2 q 2 vv + 2 p 2 vv − ⊥ (7.27) 2 2
=
⊥
⊥
v + + k v − v + + k v − q = Q ∗ +1+ k q Q ∗ v + + k q v − v ⊥+ v ⊥ − +1 − -
q
p

2
2
kpP∗v+ +kpv− v+v⊥−⊥Q~
Q
which indicates that the required active and reactive power is satisfied with a super-
position of power oscillations. If the relationship of the two flexible scalars are cho-
sen as k = − k = k (−1 ≤ k ≤ 1), oscillations in active power or reactive power can
p
q