Standalone hybrid generation system for the remote area of Thar, Pakistan
regulate the dc-link voltage or rotor speed. This arrangement causes high harmonic distortion, which
reduces generator efficiency [30].
A regulated two-level rectifier can improve these distortions [29, 30]. The
primary objective of the
controller is to regulate d- and q- axis components of the stator current. The reference optimum value
of d- and q- axis current determines the operational loss of the IPMSG. The losses of a PMSG can be
divided into four components: stator copper loss, core loss, and mechanical loss and stray-load loss.
Only the stator copper and core losses are explicitly dependent on the fundamental components of the
stator currents. Therefore, optimum reference values of d- and q- axis components
of stator current
have to be calculated to reduce the operation loss. An algorithm is developed to obtain the optimum
reference value of d- and q- axis current to ensure minimum operational loss of IPMSG as discussed
in the following.
The q-axis stator current component (iq) for constant torque can be expressed as a function of the d-
axis stator current component (id):
2.27
The maximum efficiency of the IPM synchronous generator operation can be achieved by minimizing
copper and core losses. The copper (PCu) and core (PCore) loss for the IPM synchronous generator
can be determined as follows [31].
2.28
Where R
c
is the core loss component.
The output power from the generator can be given as:
2.29
The optimum value of id can be determined from the output power (Pout) vs d-axis stator current (id)
curve based on (2.28) as shown in Fig. 2.9. From Fig. 2.17, optimum value
of the d- axis current
component is chosen where the output power from IPMSG is maximum. The controller is shown in
Fig. 2.18.