Research On Photovoltaic Islanding Detection Based On Slip-mode Frequency Shift

Along with the increasingly development of economy, the energy produced in the world can no longer meet the needs of human development. A second question is the search for new energy, thus the application of solar energy is becoming more and more widely. And the form of photovoltaic power generation is also the emerging industries. Grid-connection is the most important in Photovoltaic power generation system. In the process of grid connection, the problems that are difficult to break are the island detection, and only when this issue is resolved can we ensure safe and stable operation of power grid.When the grid fails, or circuit breaker is disconnected due to some reasons, this will cause the photovoltaic power generation system separated from the grid, thus forming an island effect. When island effect occurs, if the island signal is not quickly detected, it will produce the corresponding hazards such as: inverter live working time, can cause life hazard to detect personnel; Inverter with no load out, can produce devastating damage to load; Photovoltaic system and the grid is not out of the affect the dissertation quality of power grid, and so on. In order to make accurate and rapid removal of the islanding, the islands of the generation and detection of signals are studied in this dissertation, and through the corresponding algorithm are simulated, prevent island in a better way.Single-phase photovoltaic grid dissertation generation is the most basic, first of all, choose to study in the process of the photovoltaic grid need related variables,such as(DC/DC),(DC/AC), LC filter, current loop and voltage loop and maximum power point tracking, etc. Through the design and calculation of grid-connected Photovoltaic power generation system, simulate the corresponding waveform.Secondly, on the basis of single phase photovoltaic grid-connected power generation, extending the three-phase photovoltaic grid power inverter for interconnection is stable. Application of sliding Mode Frequency drift method(Slip-Mode Frequency Shift, SMS), this dissertation introduces the methods of the SMS island detection set up SMS detection system simulation model, get the SMS in the simulation test method of bus real-time detection, SMS about the detection of inverter, SMS to detect inverter, when found island signal, it quickly removes the grid.Finally, optimize the SMS algorithm, introducing the IM-SMS algorithm and through constructing Matlab/Simulink photovoltaic grid island detection model and simulation, comparing IM- SMS algorithm with SMS algorithm, all those shows that the improved algorithm can detect island signal more accurately and quickly, and it also can reduce the detection blind area.Learning through the study of this dissertation, the IM-SMS algorithm to detect islanding can be more effective than the traditional SMS, and thus improve the security and stability of the photovoltaic grid dissertation generation.