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DC side voltage should be no more than the max. DC input voltage of the MV
Station.
Too high DC voltage may damage the module even cause safety incident.
To ensure system reliability and device operation, PV cells on the DC side of the
MV Station should be from the same manufacturer and the number of PV cells in
each string should be the same.
Check the PV arrays before grid-connection. The voltage of each DC main cables should be
the same and no more than the max. permissible DC voltage. Check carefully the polarity of
each DC main cable. Once the polarity in one DC main cable is incorrect, the PV arrays may
be damaged.
Make sure the environmental condition is stable since the voltage of PV array may change
with the solar radiation and the temperature of the PV cells. Record the PV array status via
the U-1 curve. Commission the device when the PV array output situation is stable.
The PV field circuit fault (module fault or module numbers deviation in certain
array), cable damages or connection looseness may cause the voltage deviation
exceeding 3% under stable environmental conditions.
•
Record the environmental parameters (temperature, radiation, etc.).
•
Measure the resistance of cables (between the terminal box and the module).
•
Record accurately all the measured datas.
7.3.4 Checking Grid Voltage
•
Measure accurately the grid 3-phase line-to-line voltages: L1-L2, L1-L3, and L2-L3. The
voltages should not exceed the grid permissible voltage, and the three phases are in
balance.
Adjust the transfer ratio of the transformer by qualified personnel if the grid
voltage deviation is serious.
•
Measure and record the grid frequency. Measured datas should not exceed the grid
permissible frequency.
•
Measure the THD and check the curve if possible. Inverter will stop running if the THD is
not correct.
•
Record accurately all the measured datas.
System Manual
