User Manual
31
Scenario 2:
Several inverters are operated in parallel connection to low-voltage side of MV
transformer. The high-voltage side of MV transformer is connected to the Middle
Voltage Grid.
Requirements:
If the number of the grid-connected inverters exceed 40, please contact
Sungrow to confirm the technical solution.
The rate voltage on the low-voltage side of transformer must meet the inverter
output electrical specification. A neutral point is necessary and must lead
outwards as neutral conductor.
W2
V2
U2
W1
V1
U1
Low-voltage
Side
High-voltage Side
MV Transformer
Inverter 1
Inverter 2
Inverter n
Medium-voltage Transformers
The following requirements must be observed when installing medium-voltage
transformers:
The transformer for the inverter can be a distribution transformer, however it
must be designed for the typical cyclical loads of a PV system(load in the day
and possibly no load at night).
The transformer can be of the liquid-immersed type or dry type. Shield winding
is not necessary.
The line-to-line voltage on the low-voltage side of the transformer must endure
the output voltage of inverter. When connecting to the IT grid, the
withstanding voltage of the low-voltage winding side of the transformer, the
AC cables and the secondary devices (including the relay protection, detection
& measuring, and other related auxiliary devices) to the ground should not be
lower than 1100V.
The line-to-line voltage on the high-voltage side of medium-voltage
transformer should comply with the power grid voltage of installation site.
A transformer with a tap changer on the high-voltage side is recommended in
order to remain consistent with the grid voltage.
