Abstract:
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Static synchronous compensators have been broadly
employed for the provision of electrical ac network services,
which include voltage regulation, network balance, and stability
improvement. Several studies of such compensators have also been
conducted to improve the ac network operation during unbal-
anced voltage sags. This paper presents a complete control scheme
intended for synchronous compensators operating under these
abnormal network conditions. In particular, this control scheme
introduces two contributions: a novel reactive current reference
generator and a new voltage support control loop. The current
reference generator has as a main feature the capacity to supply
the required reactive current even when the voltage drops in
amplitude during the voltage sag. Thus, a safe system operation
is easily guaranteed by fixing the limit required current to the
maximum rated current. The voltage control loop is able to imple-
ment several control strategies by setting two voltage set points. In
this paper, three voltage support control strategies are proposed,
and their advantages and limitations are discussed in detail. The
two theoretical contributions of this paper have been validated
by experimental results. Certainly, the topic of voltage support is
open for further research, and the control scheme proposed in this
paper can be viewed as an interesting configuration to devise other
control strategies in future works. |