Study On A Combination Of Active And Passive Islanding Detection Scheme

With the development of global economy,the level of industrial and domestic consumption is increasing continuously too. The traditional way of electric power generation is affected by the energy shortage and environmental pollution factors,so some other ways to generate the electric power must be found. In the context, Distributed Generation systems such as photovoltaic power, wind power,geothermal power generation, fuel cell and so on as the new energy structure get rapid development because of its environmental protection and energy saving, efficient advantages.At present,the research about Distributed Generation energy has been studied and discussed all over the world.It is expected, Distributed energy will be a dominant energy that guides the development of electric power industry in the world. When a variety of distributed energy is developing more and more quickly, Island effect wich is closely related to the distributed energy issues also attractes wide spread attention. Islanding effect problem has been around for decades,many countries around the world have developed a variety of techniques and approaches to carry out anti islanding protection.In this paper, firstly, the existing islanding detection methods are classified and summarized. They can be divided into two categories: local Islanding detection method and Islanding detection method based on telematics systems. Then the analysis and research on the more popular islanding detection methods which from the two categories is summarized. Especially,the analysis and research on the current relatively mature passive over/unde voltage and over/under frequency of islanding detection method and the active frequency drift islanding detection method(Active FrequencyDrift, AFD) is carried out;through the theoretical analysis,the advantages and disadvantages of this two kinds of methods are summarized; Then analysing and summarizing the advantages and disadvantages of the PLCC islanding detection method.This paper has two main innovations:The improvement and innovation based on traditional AFD islanding detection method is studied,then a new kind of AFD islanding detection method is put forward wich has the advantage of periodic intermittent disturbance. This paper proposes a combination of active and passive islanding detection scheme, and the implementation strategy of this scheme is described in detail. The effectiveness of this islanding detection scheme is verified by the simulation in this paper.The main contents of this paper:(1) With the large-scale application of distributed generation system, analysing the generation mechanism of islanding and islanding detection principle,focusing on the advantages and disadvantages of passive over/under voltage and over/under frequency islanding detection method, AFD islanding detection method and PLCC islanding detection method. Summarizing the advantages and disadvantages of the three methods.(2) The improvement and innovation based on traditional AFD islanding detection method is studied,and a new kind of AFD islanding detection method is put forward wich has the advantage of periodic intermittent disturbance.(3) A combination of active and passive islanding detection scheme is put forward in this paper, and the implementation strategy of this scheme is described in detail. The effectiveness of this islanding detection scheme and improved AFD islanding detection method is verified by the simulation in this paper.Simulation shows that the combination of active and passive islanding detection method scheme has certain practical significance for the actual project.