Distibuted generation and reclosing coordination

Distributed generation has many detrimental impacts on reclosing. DG may continue operation during the dead time feeding fault current and thus prevent arc extinction. this leads to unsuccesfull reclosure, and the fault that would have been temporary becomes permanent. Even more severe problem may occur, when the DG units are not tripped during the dead time, and out-of-phase reclosure is possible. In the worst case there will be reclosure in phase opposition with severe consequences. The paper presents the results from simulation studies of the behaviour electricity distribution systems, when DG units are connected and automatic reclosing is applied. The simulations are basec on advanced models of distribution network distributed generators and fault arc. Some measured data is also presented for verification of the simulations. To overcome the problems, recommendations from various countries concerning DG and automatic reclosing are evaluated and approaches to solve the problems are discussed.