M.Hamzeh; Sh.Farhangi; M.Saradarzadeh

ABSTRACT
One of the most important features of grid connected photovoltaic sources is to detect islanding
condition in less than 2 seconds according to relative standards. Passive anti-islanding method have no
proper response due to large non-detection zone. Therefore, usually active anti-islanding schemes are
used in photovoltaic sources. One of these schemes is Active frequency drift method which drift the
frequency of islanding zone out of permitted limit when islanding occurs to make the frequency relay trip
the Photovoltaic source. Results show that this method has a high efficiency operation in islanding
detection. But this method inject a little disturbance to the network, which increases the current
harmonics. Therefore the method parameters should be adjusted to keep the current THD in the
acceptable range in the system. Finally the implementation algorithm of this method in a single phase
inverter is presented.

KEYWORDS:
ANTI-ISLANDING PROTECTION , ACTIVE FREQUENCY DRIFT WITH POSITIVE FEEDBACK, GRID
CONNECTED POWER CONDITIONER UNIT