Research On Islanding Detection Methhod Of The Multi-source Micro-grid

Increasing of energy demand, environmental pollution and energy shortage in recent years, the development of new energy micro-grid technology shows a great prospect. With the characteristics of zero pollution, renewable and resources universality, this type of power generation improves the stable operation of the power system while the waste of energy loss is reduced, thereby enabling the economic costs of electricity investment decreased. But with the micro-grid access to the power system leads to the structure changes of the distribution network, in which hazards on the power grid, equipment and personal were hidden. Thus, with new technologies to join in, the related issues in security and reliable operation of power grid have become quite important. Islanding detection as one of the important parts of the detection and prevention of the power system has drawn attention.Under the premise of islanding detection algorithm, firstly, network topology of micro-grid connected to the distribution network is analyzed, advantages and disadvantages and application conditions are introduced, and then reasonable islanding scheme is proposed to prepare for the study of islanding detection algorithm. Secondly, advantages and disadvantages of the epidemic Islanding detection algorithm are compared and research direction is determined. Thirdly, aiming at achieving a fast and accurate detection results, an improved Slip-Mode Frequency Shift (IM-SMS) algorithm is proposed, this method can achieve good detection results for a single DG in micro-grid, but there is a shortcoming that power quality is affected. Lastly, aiming at the disadvantages of mutual interference between different detection channels of multiple DG and the influence on power quality because of the disturbance variable, a kind of impedance measurement is proposed, not only to solve above problems, but also to achieve the effective detection of multi-source micro-grid.Matlab/Simulink is used for setting up the detection system and the simulation study is processed afterward. The experimental results show that the proposed method can detect the islanding fast and accurate.