Abstract. In this paper, we i n vestigate the links between planning and plans execution. We propose a new approach ( Propice-Plan) w h i c h i n tegrates both activities. It implements supervision and execution capabilities, combined with di erent planning techniques:{ plan synthesis to complement existing operational plans and { anticipation planning to advise the execution for the best option to take when facing choices (by a n ticipating plans execution), and to forecast problems that may arise due to unforeseen situations. This approach relies on a common language to represent plans, actions, operational procedures and constraints. In particular, the description we p r o p o s e makes transitions between planning activities and execution seamless. This work is used in two complex real-world problems: planning and control for autonomous mobile robots, and for the transition phases of a blast furnace.

This paper presents an alternative implementation of a modular multilevel converter (MMC) that generates a large number of voltage levels per phase with high resolution voltage steps from a reduced number of cells per arm. The presented MMC employs a half-bridge chain-link of medium-voltage cells and a full-bridge chain-link of low-voltage cells in each of its arms. The total blocking voltage of the full-bridge chain-link is equivalent to half that of the medium-voltage half-bridge cell. The use of half and full-bridge cells with two distinct rated voltages in each arm permits full exploitation of the full-bridge cells to generate high resolution multilevel voltage waveforms with fine stepped transitions between major voltage steps of the medium-voltage half-bridge cells. In this manner, errors in the synthesis of the common-mode voltages of the three phase legs due to switching of the cell capacitors in and out the power path are reduced. The nested multilevel operation of the proposed MMC results in a number of voltage levels which is related to the product, rather than the sum, of the numbers of half and full-bridge cells. Detailed comparisons with existing MMC implementations show that the proposed MMC implementation offers the best design trade-offs (superior AC and DC waveforms with reduced control and power circuit complexity). The validity of the proposed MMC implementation is confirmed using simulations and experimentally.

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Future multiterminal high-voltage direct-current (HVDC) grids are considered an enabling technology to efficiently integrate large amounts of renewable energy into the existing grid. However, already in today's existing point-to-point HVDC links, harmonic interaction issues and instabilities related to the control and protection system of the converters have been reported. The converter control software is usually black-boxed and problems are therefore solved in close cooperation with the HVDC vendor. This paper aims to provide a starting point for a discussion on an open-source HVDC control system. In particular, it covers the control design including technical and non-technical aspects. The open-source approach can be useful to solve current as well as future control-related problems, both in point-to-point links as well as in multiterminal and multivendor HVDC grids.