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D=E
'
F
23G,' For instance, if, at the end of the annual simulation, D=0.5, the battery is half-way through its
lifetime. In other words, the battery will need to be replaced every two years. Since battery lifetime
is drastically affected by deep discharge cycles, only part of the available capacity is used for daily
cycling. The battery is never discharged deeper than SOCmin. A SOC≥SOCminconstraint
applies. The SOCmin value is type-specific and can be obtained form the manufacturer’s data
sheet.
Simulation results for the batteries show both the total number of cycles run and the deep cycles. In
the battery properties dialogue box, a deep cycle threshold defines what may be classified as “deep
discharge”.
Controller
In Polysun, batteries are equipped with an automatic controller as a standard. If necessary, the
battery may also be controlled by means of the available programmable controller.
The controller works based on a calculation of the system’s net power Pn(t) = generated power –
consumed power.
Automatic controllers work on this basic principle: the battery is charged when a sufficient amount
of self-generated power is available and discharged as soon as a power deficit occurs. The battery
is never charged off the mains.
Description of an automatic controller:
1. When the system generates an amount of power in excess of what is consumed (Pn(t) > 0)
the following charge pattern applies:
a. Charge battery with maximum possible, available power as long as it can be
charged.
Pch(t)=min OPnt,Pch,maxtP
b. Feed remaining power into the grid.
Ptegt=Pnt-Pcht
2. When the system consumes more power than it generates (Pn(t) > 0) the following
discharge pattern applies:
a. Discharge battery to maximum possible extent as long as it can be discharged.
Pdis(t)=min O|Pnt|,Pdis,maxtP
b. Draw the remaining power from the grid.
Pfegt=Pnt+Pdist
The battery offers two inputs for the programmable controller:
Input
Control mode
Controlled
power
Description
Shows how the battery is
controlled
Battery power may be set.
Value
0: automatic controller (default value)
1: controlled battery power is used
> 0: the battery is charged, value in [W]
<=: the battery is discharged, value in [W]
Template 50h provides an example of explicit battery control.
User Manual Polysun
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