This method is a technique that relies on the use of the power line as a communication channel (Report IEA-T5-09, 2002), (Ropp et al., 2000), (Xu et al., 2007). The basic idea is to transmit a continuous low-energy signal between the transmitter (T) located on the side of the grid and receiver (R) located on the side of the DG. When this communication is disrupted, the receiver send a stopping signal to the inverter and/or a switch (included in the receiver) should be opened in order to isolate the load from the DG. The scheme of this method is shown in Figure 15.
Fig. 15. PLCC system with both transmitter (T) and receiver (R) devices
Among others, the advantages of the method are: Ability to operate in areas with high density of DG. It does not have an NDZ. The inverter output power quality is not degraded. Its transient response depending on the type of signal to transmit, it is possible to use only one transmitter to cover a part of the grid.
Some of the weaknesses of this method are: the cost of the receiver and transmitter can be too high. Moreover certain charges under certain conditions highly abnormal, might replicate the emitted signal by the PLCC which would result in non-Islanding detection.