Intelligent power electronic systems for the grid interaction with large scale integration of RES

Grid interaction could cause the unreliability and instability, particularly in the presence of large scale integration of RES (renewable energy sources) in the electrical power distribution networks. Therefore, the required intelligence of power electronic system are analyzed and assessed in cases of grid interaction (grid connected, islanding and re-connecting) in this paper. The concepts of power balance in the AC grid and on the DC bus are also presented. The principles of dynamic voltage restorer are implemented in the prototype of dual coupled voltage source inverters. The test results prove that the prototype system has very fast response to restore the AC voltage. In addition, the principle of dynamic power balance on the DC bus with super capacitors is also presented and verified. With the presented principles, the goal of locally balance the power difference can be achieved on the DC bus as well as in the AC grid. As a result, more renewable energy sources can reliably be integrated in the existing electrical power networks.