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As the number of wind power applications with power electronic interfaces in the grid increases, it is becoming unacceptable to disconnect the generating units every time disturbances occur, especially under voltage dips, as was a common practice in the past. Keeping the converter online during unbalanced voltage, and guaranteeing the actual standards of the converter connected to the grid, is becoming a very critical issue. From these goals, the design of a robust back-to-back neutral point clamped (three levels) voltage source converter of 150 kVA is developed in this paper. The converter is divided into two main parts: the power electronic system and the control electronic system. Concerning the first part, on the one hand, the paper presents the designs of active and passive components as insulated gate bipolar transistor, free-wheeling diodes, clamping diodes, grid filter, dc-bus capacitors, etc.; and on the other hand, the converter requirements are analyzed to ride through real grid conditions, i.e., unbalanced voltage dips. Concerning the control electronic system, the chosen electronic structure and the task distribution between the two processors used are shown.Index Terms-Back-to-back neutral point clamped (NPC) converter, dc-bus capacitors, DSP and field-programmable gate array (FPGA), local control level (LCL) filter, voltage dip.

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The objective of this paper is to analyse the influence of a non-ideal grid over hysteresis controllers of\ud converters connected to the grid through both L and LCL filters. The paper will describe the different\ud possible configurations in both cases, analysing the effect of a general R-L grid. Limit values for both\ud grid inductance and resistance are given for the L structure. In the case of LCL connection, the analysis\ud will overview important issues such as active damping, and switching behaviour giving limits to stability\ud as a function of grid impedance value.Postprint (author’s final draft

This paper presents a sensor system for robot localization based on the information obtained from a single camera attached in a fixed place external to the robot. Our approach firstly obtains the 3D geometrical model of the robot based on the projection of its natural appearance in the camera while the robot performs an initialization trajectory. This paper proposes a structure-from-motion solution that uses the odometry sensors inside the robot as a metric reference. Secondly, an online localization method based on a sequential Bayesian inference is proposed, which uses the geometrical model of the robot as a link between image measurements and pose estimation. The online approach is resistant to hard occlusions and the experimental setup proposed in this paper shows its effectiveness in real situations. The proposed approach has many applications in both the industrial and service robot fields.

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