Comparative Study of Passive and Active Islanding Detection Methods for PV Grid-Connected Systems

Abstract

Photovoltaic (PV) power grid-connected systems have the advantages of being prompt and reliable supplies of electrical power. Nevertheless, the installation and operation requirements from the grid side have to be fulfilled in order to guarantee the security of the PV system technicians and the efficiency of the power system. Particularly, the potential for "islanding" is one of the dreads that are brought about by PV grid-connected systems. To be able to tackle these concerns, this paper investigates recent islanding detection techniques and topologies for PV systems. Active islanding detection techniques apply regular disturbances to the inverter system and then analyze the output voltage or frequency to investigate the islanding and stability of the grid. If the injected disturbances influence the load voltage or frequency, the controller forces the intermediate inverter to stop sending power to the connected load. In addition, several islanding detection techniques that inject a periodical signal to the reference current that causes a change in the magnitude of inverter output voltage when islanding happens in a three-phase photovoltaic grid-connected system are discussed. The validity of the proposed technique is tested and verified through PSIM software.

Comparative Study of Different Approaches for Islanding Detection of Distributed Generation Systems

“…It means that an additional external variable, positive feedback or controlled change is introduced, which interact with the power system operation providing the significant change in system parameters during islanded conditions and negligible change during proper operation of the DG in grid. It involves the feedback technique or some mechanism to find islanding through parameters change [58]. This method is more accurate and effective than the passive method due to relatively small NDZs, but it has slow response toward the perturbation.…”

A Research of Islanding Detection Method for Distributed Generation: Mechanism, Merits and Demerits

“…7 [34], [35]. The interference is defined as the chopping fraction, (ratio of zero conduction period, to half of utility voltage period, ) which is expressed in (8) [36]. These interference increase phase error of the DG output during islanding phenomenon hence, leading to the frequency drift in order to eliminate the error.…”

“…These interference increase phase error of the DG output during islanding phenomenon hence, leading to the frequency drift in order to eliminate the error. If the frequency drift surpassed the predefined boundary, OUF relay detects the islanding and at once ceases the DG activity [36].…”

“…SFS is entitled after Sandia National Laboratories (SNL) that developed the method [40]. SFS is almost the same as AFDPF scheme with further innovation of the AFD [36]. The chopping fraction is as represented in (11).…”

“…Hence in the event of islanding, the DG output voltage is drifted surpassing the predefined boundary. Therefore, OUV relay will detect and cease the islanding activity [36]. The combination of SFS and SVS is highly efficient in which the NDZ registered is almost zero.…”