—Static compensators can be used for voltage
regulation in the presence of flicker or transients on parallel
connected loads in a distribution system.
This paper presents a
general modeling strategy that allows design of a fast voltage
magnitude controller accounting for system parameters.
ordinate transform used in modeling the system facilitates
extraction of linearized system dynamics with the help of circuit
It is also shown that the problem of voltage
regulation using instantaneous reactive current is non-minimum
phase for certain operating conditions, thereby limiting its
dynamic response irrespective of the control design method.
Simulation results with a controller designed using input output
bode plot are presented to prove the efficacy of the proposed
—Flicker mitigation, Modeling, STATCOM,
STATCOM control, Voltage regulation.
ast load voltage regulation is required to compensate for
time varying loads such as electric arc furnaces,
fluctuating output power of wind generation systems, and
transients on parallel connected loads (e.g. line start of
induction motors) -.
Reactive power compensation is
commonly used for flicker mitigation and load voltage
Due to their high control bandwidth, Static
Compensators (STATCOMs) based on three phase pulse
width modulated converters, have been proposed in , -
 for this application.
For effecting fast control, the
STATCOM is usually modeled using the
axis theory for
balanced three phase systems, which allows definition of
instantaneous reactive current .
Most literature on STATCOM control concentrates on
control of STATCOM output current and dc bus voltage
regulation for a given reactive current reference.
of load voltage is achieved using a PID controller that
generates the reactive current reference (e.g. ).
paper it is assumed that the STATCOM can be modeled as a
controlled current source.
The problem addressed here is to
design a voltage magnitude controller that will generate the
reactive current reference for the STATCOM.
experimental procedures like Zeigler and Nichols , to the
A. K. Jain and N. Mohan are with the Department of Electrical and
Computer Engineering, University of Minnesota, Minneapolis, MN 55455.
(phone: 612-624-7309, fax: 612-625-4583 E-mail:
A. Behal is with the Department of Bioengineering, Clemson University,
Clemson, SC 29634-0915.
authors’ knowledge, there is no standard procedure for
designing a load voltage controller that ensures the required
bandwidth and robustness to system variations.
In , a small
signal model of the system was derived by transforming the
equivalent impedance of the ac system to the