Page 67 - Hybrid-Renewable Energy Systems in Microgrids

Integrated renewable energy sources with droop control techniques-based microgrid operation 51

Figure 3.9 Virtual impedance droop control [31].

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and the X/R ratio of the line impedance θ = tan −1 XR and the line frequency can θ=tan−1X/R
present at the output impedance of the angle.

7 Case study of solar PV and BESS with P/Q and V/f
droop control

In the microgrid system, the solar PV and the battery are operated in grid-connected
mode and islanded mode of operation. During the grid-connected method, active and
reactive (P/Q) droop control has been operated, although voltage and frequency (V/f)
droop control can be operated under islanded operation. The voltage and frequency
should be stable, balanced power flow are the necessities of PV generators in the
microgrid operation.
Fig. 3.10A represents the P/Q droop control inverter, which operates by the active
and reactive power injecting into the utility grid defined locally or centrally. The
actual voltage and frequency are exceeding to the droop control block to generate
the active and reactive power reference signals. These reference signals compared
with the actual and error values through PI controllers. The droop equation of P/Q
control is given by,