| The environmental pollution has become increasingly serious and the fossil source will be exhausted in the near future. So this phenomenon promotes and accelerates the development and utilization of new energy. The wind power generation technology is the most mature in the new energy, large-scale wind power connecting to grid has become an inevitable trend. Megawatt doubly fed induction generator (DFIG, referred to as double-fed turbines) has become the mainstream model recently, developing rapidly.However, the topology of the distribution network will be changed when the wind power connects to power grid, and it will make the distribution of the power and the power flow get more complex, the setting condition of the current protection of the traditional distribution network has been changed. So it would lead to a series of problems, such as, the sensitivity of the protection dropping down, refuse action, unexpected action, which cannot satisfy the requirement of distribution network with the wind power, there would be a great hidden trouble to the power system to operate stably. Therefore, it’s important to study on the influence of the wind power access to distribution network of relay protection.Firstly, this paper analyzes as the following aspects, the working principle, mathematical model and vector control strategy of the DFIG, respectively. The model of grid connected is established on RTDS/RSCAD. And then study on the characteristics of the grid connected operation and the fault by the simulation of RTDS/RSCAD, realizing the power decoupling control. Secondly, the paper analyzes the effects of wind power connecting to the distribution network on the traditional three-phase current protection and the automatic reclosing device from the aspect of theory. And it also present the impact of the wind power connected to different locations and different capacity on the protection. A10kV distribution network simulation model with wind power farm connects to grid is established on RTDS/RSCAD, carry out the setting calculation for without the wind power of distribution network, simulation and verification the protection. With the wind power of distribution network model, by setting different fault locations, different wind power capacity and different length of lines. We emulated and validate that when the wind power capacity reaches a certain value, the access point upstream protection would take false action and the scope of protection of downstream protection current quick break would increase. The changing of the line’s length also has the varying degrees of impact on protection. Lastly, for the distribution network with wind power, we adopt a new method that combining the partition longitudinal differential protection and the over current protection, with10kV distribution network model for object to carry out the calculation, simulation and validation. Actually, the results prove that the new method can ensure the reliability of protection, and satisfy the requirement of the relay protection of the wind power connects to the distribution network. |
PDF Full Text Request