Research On The Anti-Islanding Method For The Renewable Resource Stations Of Large Scale

With the exploitation of global fossil energy,energy problem is becoming more and more serious.According to statistics,oil resources will be exhausted in around 2050,the countries which rely on traditional energy will suffer a loss.Therefore,developing renewable energy,reducing the use of fossil energy and improving the use of renewable energy such as solar energy becomes a key factor in solving the problem of energy crisis for most countries around the world.Renewable resources generation is an important way of utilization of renewable energy,the study of.The inverters of renewable sources should be equipped with islanding detection scheme,for this reason the traditional islanding detection method focuses on renewable resource system islanding detection method based on the inverter.But as the development of the renewable resources generation,the scale of the renewable resources generation becomes bigger and bigger,the new islanding detection to detect the islanding occurs on the situation of the renewable resource stations of large scales are commanded.In order to solve the problem of islanding exists in the renewable resource stations of large scale,this paper analyzed the situations of islandings under such circumstance,concluded two characteristics of it.And this paper analyzed the situation of NDZs(non-detecting zones)when the power attracted by the loads and shed by the generations matches,and a method to eliminate such NDZs is proposed.According to the two characteristics analyzed in this paper,four methods to detect islanding is proposed.Specific innovation points are as follows:(1)An islanding detecting method based on the combined criterion of frequency and power-factor is proposed to improve the islanding efficiency.(2)An islanding detecting method based on the amount of frequency mutation is proposed,and it is a passive method with high detecting efficiency;(3)An islanding detecting method based current delivering is proposed,which is easier to realize compared with the tradition methods based impedance measurement.Miscalculation(4)An islanding detecting method based on fuzzy control is proposed,it can improve the islanding efficiency and lessen the affect to the electric power quality.(5)An islanding detecting method based on two level of capacitance is proposed,it is easier to realize and could improve the detect efficiency compared with the traditional methods based on the capacitance.The renewable resource system model is set up by MATLAB/Simulink.The new algorithms were verified and tested in the simulation mode.