grid failure. Therefore, reliability and efficiency of the PE converters
and controllers produces a beneficial impact on the total
system performance.
3.1. Control techniques
The PE converters are supervised by different control techniques.
The controllers are mandatory to control the machine parameters in
order to operate the machine as desired. Presently, various researchers
extensively analyze and designing several types of controllers discussed
in [79–85] and are tabularized in Table 2. From the literature
available, numerous solutions are based on the enforcement of
advanced power electronics functionalities in the existing rotor or
grid side converters [76]. Among the various control techniques, few
familiar controllers have discussed in the next sections.
3.1.1. Scalar control
Scalar control is based on varying two parameters simultaneously.
It is a steady state direct control involves controlling the
magnitude of voltage and frequency of the induction motor and
used as V/Hz constant. The wide range of smooth speed with
maximum torque remains unchanged and obtained through
proper tuning of voltage and frequency [77,104].
3.1.2. Vector control
It is a dynamic indirect control mainly used in a synchronous
and induction machines for attaining high performance. The
analysis of vector control is based on the vector representation
Table 2
Various control techniques used for hydro generators.
Sl.No Control Techniques Machine
type
Type of Power Electronic Converter Application Year