09-07-2012, 03:24 PM
Grid Voltage Regulation Utilizing Storage Batteries in PV Solar – Wind Plant based Distributed Generation System
Grid Voltage Regulation.pdf (Size: 743.81 KB / Downloads: 1,655)
INTRODUCTION
AS the penetration level of the renewable energy resources
(such as wind, solar, fuel cells, etc) is increasing,
dependence on these resources to support load demand in
modern power distribution system is also growing. However,
due to the intermittent nature of wind and solar resources, the
reliability of distributed generation (DG) is a major concern. A
backup battery, if integrated with these resources, may help to
store the excess energy produced by them and deliver it
whenever needed.
A photovoltaic (PV) solar farm produces power during the
day-time. However, it generates close to rated maximum
power only during part of the day-time (late morning to late
afternoon/early evening) hours.
PV SOLAR FARM AS BATTERY CHARGER
A typical PV solar farm is basically inactive during nighttime
and the bidirectional inverter used to deliver the PV DC
power as three-phase AC power to the grid, remains unutilized
as well. Fig. 2 shows the possible operational modes of the
solar farm. The point at which the solar farm is connected to
the grid is called the point of common coupling (PCC). In Fig.
2, vS and iS represents the voltage and current at the secondary
of the distribution transformer; vPCC and vL denote voltages at
PCC and load terminal respectively; and iPV is the current
delivered by the PV solar panels. AC current drawn/delivered
by the solar farm inverter and the DC current flowing through
the storage battery are represented by iSF and iBatt, respectively.
SIMULATION RESULTS
To validate the concept presented in the paper, MATLAB/
SIMULINK based simulation study is carried out. A
SIMULINK model is developed for the system discussed in
Fig. 3. The length of line L1, L2 and L3 are: 5 km, 1 km and
0.5 km, respectively. The impedance of each of the line is:
0.055 + j0.0395 (positive sequence value) and 0.1763 + j1.029
(zero-sequence value).The simulation results are given in Figs.
4 to 7.
CONCLUSION
A PV solar and wind plant based distributed generation
system with battery storage is studied in this paper. The
bidirectional inverter of PV solar farm is utilized as a battery
charger especially during the night-time to charge the
batteries. A new concept of indirect feeder voltage control is
presented in which the voltage rise (due to a substantial
amount of reverse power flow from the wind farm) is
controlled by utilizing the solar farm inverter to charge the
batteries. The solar farm inverter is operated as a three-phase
controlled rectifier which draws sinusoidal currents at unity
power factor operation.