Implementation of a Synchronverter Virtual Synchronous Machine for Double Fed Induction Generator Connected to a Microgrid
Microgrid. Batteries. Virtual Synchronous Machine. Synchronverter. DFIG. PLL.
The high integration of Distributed Generation (GD) to the conventional electric system
brings many challenges to the operating sector, given the growing concerns about the
reliability of the system and the quality of the energy generation. The DGs have no control
over the generated energy, although they have very fast power dynamics, with little or no
inertia. In order to mitigate the impacts caused by the integration between the GD and the
existing system, it is essential to use the concept of a virtual synchronous machine, whose
fundament search to emulate the behavior of a real synchronous machine by VSI (Voltage
Source Inverter) control. In this context, this work proposes the development of a control
strategy aimed at controlling the DFIG (Doubly Fed Induction Generator) aerogenerator
so that all necessary requirements can be met to maintain the stability of the grid. The
purpose will be achieved starting from the assumption that the VSI connected to the grid
will have similar behavior to a synchronous generator, since the control technique will
be used Synchronverter. Thus, in addition to greater control over the active and reactive
powers generated, it is also possible to obtain a contribution with the ancillary services. In
addition, the DC bus of the back-to-back converter must be connected to a battery bank,
which will enable greater control over the power dispatch. Therefore, it is possible to
charge the batteries in the horaires of greater generation and lower energy consumption
of the grid, as well as to discharge the batteries in the moment of demand of support to
the frequency of the grid. Preliminary results confirmed the functioning reported in the
literature, proving the effectiveness of the technique, with potential for improvements that
the work aims. Finally, with the use of the Synchronverter, it will be possible to operate
the DFIG autonomously in a microgrid in the occurrence of a Blackout in the system and,
after ceasing the collapse in the system, synchronize the VSI to the grid without the need
to use a PLL (Phase Locked Loop).