Modulated model predictive control for a 7-level cascaded h-bridge back-to-back converter

Multilevel Converters are known to have many advantages for electricity network applications. In particular Cascaded H-Bridge Converters are attractive because of their inherent modularity and scalability. Predictive control for power converters is advantageous as a result of its applicability to discrete system and fast response. In this paper a novel control technique, named Modulated Model Predictive Control, is introduced with the aim to increase the performance of Model Predictive Control. The proposed controller address a modulation scheme as part of the minimization process. The proposed control technique is described in detail, validated through simulation and experimental testing and compared with Dead-Beat and traditional Model Predictive Control. The results show the increased performance of the Modulated Model Predictive Control with respect to the classic Finite Control Set Model Predictive Control, in terms ofcurrent waveform THD. Moreover the proposed controller allows a multi-objective control, with respect to Dead-Beat Control that does not present this capability

STEROWANIE ORAZ SYNCHRONIZACJA DWUPOZIOMOWEGO FALOWNIKA NAPIĘCIA W WARUNKACH PRZEJŚCIOWEJ ASYMETRII NAPIĘĆ SIECI

This paper presents the operation of grid tied, two level voltage source inverter (VSI) during network voltage unbalance. The control system was implemented in synchronous rotating reference frame dq0 (SRF). Two types of control structures were investigated herein. First utilizes the Double Decoupled SRF Phase-locked loop (DDSRF-PLL) synchronisation with positive and negative sequence currents control. Second one is simplified system that does not provide symmetrical components decomposition and decoupling for synchronisation. Simulation results exhibited a superior performance of the DDSRF-PLL control system under grid voltage unbalance.Niniejszy artykuł przedstawia pracę dwupoziomowego falownika napięcia współpracującego z siecią, podczas przejściowej asymetrii napięć. System sterowania został zaimplementowany w wirującym układzie synchronicznym dq0. Przeanalizowano dwa typy sterowania. W pierwszym zastosowano metodę synchronizacji z odprzęganiem DDSRF-PLL wraz z możliwością kontroli prądów składowej zgodnej i przeciwnej. Drugi natomiast w swoje uproszczeni formie nie pozwalała na sterowanie obu składowych symetrycznych, zabrakło również odprzęgania podczas synchronizacji z siecią. Wyniki symulacji pokazały o wiele lepsze działanie pierwszej metody sterowania

Predictive control for active split DC-bus 4-leg inverters

This paper proposes a Predictive Control, formally Dead-Beat (DBC), for a four-leg inverter having an Active Split DC-bus on the fourth leg and LC filters on phase-to-neutral outputs. Such a configuration permits to reduce the voltage ripple on the neutral point connected to inverter grounding. As only few control techniques have been investigated for Active Split DC-bus, the paper proposes to investigate the performance of DBC, which has been widely used for other power electronics applications. The main advantage of DBC over the classical PI or Resonant controller is that no tuning is required for control loop, while obtaining very fast transient response as well it can handle general constrained nonlinear systems with multiple inputs and outputs in a unified and clear manner. These features are highly valuable in power electronic converters used to supply the electrical utility loads in micro-grids. However, one of the main drawback of the DBC is the limited capabilities on harmonics compensations required when supplying unbalanced and non-linear loads. The paper presents continuous-time and discrete-time models of DBC applied to a four-leg VSI with Active Split DC-bus, highlighting the performance through simulation results as well as experimental tests

A Novel Control Method For Grid Side Inverters Under Generalized Unbalanced Operating Conditions

This thesis provides a summary on renewable energy sources integration into the grid, using an inverter, along with a comprehensive literature research on variety of available control methods. A new generalized method for grid side inverter control under unbalanced operating conditions is also proposed. The presented control method provides complete harmonic elimination in line currents and DC link voltage with adjustable power factor. The method is general, and can be used for all levels of imbalance in grid voltages and line impedances. The control algorithm proposed in this work has been implemented by using MATLAB Simulink and dSPACE RT1104 control system. Simulation and experimental results presented in this thesis are in excellent agreement

Model Predictive Control for shunt active filters with fixed switching frequency

This paper presents a modification to the classical Model Predictive Control algorithm, named Modulated Model Predictive Control, and its application to active power filters. The proposed control is able to retain all the advantages of a Finite Control Set Model Predictive Control whilst improving the generated waveforms harmonic spectrum. In fact a modulation algorithm, based on the cost function ratio for different output vectors, is inherently included in the MPC. The cost function-based modulator is introduced and its effectiveness on reducing the current ripple is demonstrated. The presented solution provides an effective and straightforward single loop controller, maintaining an excellent dynamic performance despite the modulated output and it is self-synchronizing with the grid. This promising method is applied to the control of a Shunt Active Filter for harmonic content reduction through a reactive power compensation methodology. Significant results obtained by experimental testing are reported and commented, showing that MPC is a viable control solution for active filtering systems