A new power flow method for mixed AC-DC power systems

International audienceThis article presents a new tool to solve the power flow problem for electric mixed AC-DC grids. It is based on the fixed-point theorem of contractive function. This algorithm provides some advantages over classics methods, as for example the guarantee of converge, if some mild constraints are fulfilled, or fewer calculations in each iteration with respect other methods. Different devices, as for example AC/DC converters, DC/DC converters and AC transformer are contained in the formulation. The method is tested by means of a 14 nodes mixed AC-DC grid

Dynamic feedback linearization and singular perturbation for a stabilizing controller for dc/dc boost converters: theory and experimental validation

International audienceThe current massive integration of constant power loads (CPLs) requires better dynamic performance in Direct Current (DC) microgrids. This imposes the needs for more advanced controllers for DC/DC converters, and especially for boost ones because of their non-minimum phase property. The current paper contributes to this research line and proposes an advanced nonlinear (NL) control strategy for the output voltage stabilization of boost converters using singular perturbation and dynamic feedback linearization strategies. The proposed techniques manages to impose a desired stable dynamics for the variable with the non-minimum phase characteristics, thus avoiding the problem of possible selection of unstable equilibria. At first, a theoretical proof of the stability of the close loop system with the proposed controller is provided. Then, an experimental validation composed by four case studies is performed. The results show good adaptability to a wide range of operating conditions and better performance regarding voltage tracking and load disturbances rejection of the proposed NL method with respect to classical control techniques

Nonlinear PID and Sliding Mode Control applied to a New Generation of Micro-Pump for small Satellites

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Experimental research and control of PMSG based wind turbine connected to grid

International audienceThis paper presents an experimental study of a wind energy conversion system based on a permanent magnet synchronous generator (PMSG). The objective of this work is to make an operational test bench platform and propose a control strategy for all the system (generator side control and grid side control). The wind turbine has been replaced by an emulator based on a DC motor. The proposed strategy comprises the control of the generator for maximum power point tracking (MPPT) under varying wind conditions; the DC motor is controlled so as to have the same functioning as a wind turbine. The system is connected to a three-phase network by means of: an IGBT rectifier, a DC bus, an IGBT inverter and a transformer. A detailed study of the test bench elements and its control scheme is presented. The experimental results are obtained and captured from the controlDesk software in real time using two DSPACE cards; however they show the feasibility and robustness of the proposed control strategy

A Control Strategy for Multiterminal DC Grids with Renewable Production and Storage Devices

International audienceThis paper provides a solution for the control of multiterminal dc networks from the point of view of the network's transmission system operator, which includes local, primary, and secondary controllers. A new power flow technique is validated for this approach, which guarantees the stability and requires fewer calculations than the conventional techniques. This study also describes an optimal control strategy for intermittent (renewable) energy producers, where the controller periodically transmits information about its state to the system operator. Its main goal is to optimize economic profit for the producer. This last controller is implemented via model predictive control. The whole control strategy is validated in a scaled dc grid test-bench with four nodes. Real solar production (5 kW rated power), a storage system, as well as short-term weather and consumption forecasts are also included. © 2010-2012 IEEE

An HVDC experimental platform with MMC and two-level VSC in the back-to-back configuration

International audienceIn this paper we present the realisation of an HVDC experimental platform with modular multilevel converter and two-level voltage source converter. Local control strategies for both converters are outlined in detail. The experimental platform is configured in such a way that the power-flow is controlled by the modular multilevel converter, while the DC voltage is regulated by the two-level voltage source converter. Local control algorithms are implemented by using OPAL-RT and dSpace platforms for rapid control prototyping. Experimental verification is provided. © 2016 IEEE

A new control for modular multilevel converters and their use as DC circuit breaker

International audienceThis paper presents a new modulation for modular multilevel converters (MMC) based on a simple idea, which is very easy to implement. It consists of playing with the relative behaviour of each phase in order to obtain the desired AC voltage. This method also assures that the voltage capacitor in each sub-module remains constant. Moreover, this converter allows the operation of the system under unbalanced conditions, and it can be used intrinsically as a DC circuit-breaker (DC-CB) without the need for additional power electronics and control if full bridge sub-modules are used. © 2016 IEEE and EPE Association