-In this paper, an optimal controller to control photovoltaic system using Genetic Algorithm (GA) is proposed. First, this problem will be formulated as an optimization problem consisting of objective function and constraints and then to attain the most desirable controller, GA technique could be used to solve the problem. Simulation results are performed for load variations in time domain and ...

'\B:,TRAC r· Recently there has been a resurgence of conccrn about islanding of grid-connected photovoltaic (PY) ,ystems rhis condition occurs when the PY system continues to energize a section of the grid after that section has been Isollted from thc main utility voltage source. Generally, islanding is undesirable for a number of reasons, and it is therefore important that PY systems incorpora...

Penetration of distributed generation in the power grid is increasing. This situation leads to new possibilities but also new issues, such as anti-islanding protection. During a loss-of-mains or islanding situation, distributed generation (DG) units remain feeding a part of the electrical network without connection to the main power system. Currently, DG units have to be disconnected from the g...

Islanding is the situation in which part of the power grid, consisting of load and distributed generation (DG) is isolated from the utility grid remaining active, i.e. serving load. The idea of islanding parts of the distribution network in case of faults, in order to increase the consumer quality of service, is the basic notion behind the formation of Microgrids. In the context of Microgrids, ...

In this paper Islanding detection methods for distributed resources are reviewed. The mainly used islanding detection techniques may be classified as active and passive techniques. Passive techniques don’t perturb the system but they have larger nondetection zones, whereas active techniques have smaller nondetection zones but they perturb the system. In this paper a new hybrid method is propose...

UOVR and UOFR as passive anti-islanding methods lack of sensitivity to detect islanding. The performance gets worse when the frequency threshold is increased from 50.2 Hz to 50.6 Hz. For instance, dedicated passive methods such as ROCOF help the inverter to detect islanding. When active methods such as SFS and SVS are activated, the number of detected islandings is increased to 87.5%. To improv...

The connection of inverters for distributed generation photovoltaic systems to the distribution network creates situations of risk to the loads that are connected to the point of common coupling (PCC) and personals who maintain the power grid. A risk that should be avoided is the supply of electricity, by one or more inverters, to the distribution network after disconnecting the main power grid...

This paper proposes active frequency drift (AFD) as an anti-islanding method applied to micro-inverters with uncontrollable reactive power. When using ordinary inverter topologies, such as full bridge inverters in photovoltaic systems, the islanding phenomenon can be detected with reactive power-based methods, such as reactive power variation. However, when the inverter topology cannot control ...

After microgrid transition from the normal operation to the islanded operation the system impedance changes considerably and it affects on the harmonic voltages of the microgrid. In this paper the voltage and current THD before and after islanding are studied with different microgrid configurations. Simulations are also made by applying negative sequence filtering in control system of converter...

Many owners of Distributed Resources such as synchronous Industrial Commercial Generators, ICG, are concerned about the requirements for protective relaying when connecting to a local utility even for only a short transfer time of a few seconds when paralleling to test their ICG on a periodic basis. They tend to look at the consequences of just their own ICG trying to serve a much larger utilit...