Power Electronics SD700SP Series, Hardware And Installation Manual

Page: 13 / 61

POWER ELECTRONICS SD700SP
INTRODUCTION
11
EN
Hybrid System
The SD700SP is connected simultaneously to the AC mains, (or a diesel generator), and the PV DC
field. The AC input voltage determines the SD700SP DC bus voltage and therefore the required DC
voltage from the strings. The maximum energy produced at the fixed DC voltage depends on the number
of PV panels connected in series. The number of strings in parallel will be determined according to the
pump power.
Power Electronics has developed a system, which is able to use all DC energy available and it takes
only power from the AC supply when it is needed. This system connects/disconnects the AC input to the
mains therefore avoids the need of having a "stand by" power source.
The SD700SP takes all energy possible from the PV field to pump the water needed, and if the energy
of PV field is not enough, SD700SP switches on the AC input to “top up” and deliver all energy required
by the motor. Once the energy available in the PV field is higher than the energy needed by the motor,
SD700SP will disconnect the AC input. This feature is especially important when the AC is supplied by
a generator; when the AC mains power it is not needed, the generator can be stopped.
Besides, the SD700SP has implemented a function in order to warm the diesel generator up improving
its durability.
The next figure shows the system performance with a pump continuously working. During broad daylight
the energy generated by the PV panels is injected to the motor. This helps to proportionally reduce the
power consumption from the grid. When a cloud partially covers the panels, the drive will absorb more
line power in order to keep the process constant.