In electronic circuits, island effect of a certain region refers to the circuit is designed to be with current access and the actual no current through the phenomenon. In a communication network, the island effect is wireless mobile base station coverage there may be one kind of phenomenon.
principle
The capacitors in tandem with the circuit, only deoxidization device connected the two plate (note: not the same capacitor plate) have current flow (charge exchange), other plate of total charge is constant, so called island. Island is a kind of electrical phenomenon, occurred in part of the power grid and the main power disconnected, and this part grid entirely by photovoltaic system to power supply. In international photovoltaic (pv) grid standardization on the topics that is still a point of debate, because the island will damage the public and electric power company maintenance personnel and safety of power supply quality, in manually or automatically switch to the island reclosing power grid to power supply from time to tome may damage the equipment. So, inverter usually contains prevent island effect device. Passive technology (detection grid voltage and frequency changes) in balancing the load is very good conditions electrify and again electrify two circumstances of itsself prevent enough and, therefore, must be combined with full active technology, active technique is based on the sample frequency shift, the flow of electric current impedance monitoring, phase jump and harmonic monitoring, positive feedback method, or the unstable current and phase on the basis of the controller. Now, there are many preventing measures, in the world already had 16 patent, some have been obtained, and some are still in the process of application. Among them some methods, such as monitoring network flow of current pulse was proved to be convenient, especially when many sets of the inverter parallel work, can reduce power quality, and because many sets of inverter mutual influence on his island detection negative effects. In some cases, for voltage and frequency range of work limits becomes wider, and installation workers can usually through software to set up these parameters, even ENS (a monitoring device, in Germany is mandatory) in order to succeed in the power grid work, weak can turn it off.
