Grid synchronization and symmetrical components extraction with PLL algorithm for grid connected power electronic converters - a review: In this paper, a review of Phase Locked Loop (PLL) algorithms and symmetrical component extraction methods intended for grid-connected power electronic converters are presented. Proposed classification is based on voltage representation in three coordinates: natural (abc), stationary (αβ) and rotating coordinates (dq). The three selected algorithms are described in details: Dual Second Order Generalized Integrator (DSOGI-PLL), Dual Virtual Flux - both in stationary coordinates. The third one, in rotating dq coordinates, is Dual Synchronous Reference Frame PLL (DSRF-PLL). A comparison of PLL algorithms is presented. Also, selected experimental results are given to verify practical application of discussed algorithms.

The paper describes second order generalized integrator (sogi) which is specialized in band-pass filtering and orthogonalization of periodic signals. Modifications of the structure and the influence of parameters on the system performance is described. The article highlights the particular importance of model discretization method in the practical implementation, as well as reviews estimation methods of the: amplitude, frequency, offset and phase angle of the periodic signal. Examples of simulation and experimental results are presented

This paper presents model predictive control (MPC) with a finite control states set (FS) for three-level four-leg flying capacitor (FCC) converter. Principles of control method are presented and flying capacitor voltages control method is discussed. Experimental results of converter operating as a shunt active power filter (SAPF) and grid connected inverter (GCI) are shown.

This paper proposes a structure and two strategies for hybridization of a RAT (Ram Air Turbine) with supercapacitor storage. The structure consists in coupling a High Voltage DC (HVDC) source (RAT) with a low voltage storage device through a specific topology of bidirectional DC-DC static converter. The energy management strategies consists in entrusting the storage with the “high frequency” harmonics of the load power while the RAT only produces the average power: the RAT sizing and its mass can then be reduced. Lab test bench architecture, control strategy, topology of the converter and experimental results are presented in this paper.

Modern distribution grids may suffer problems of voltage distortion, especially along radial low-voltage feeders with a high penetration of intermittent, unbalanced and distorted loads and generation sources. It is a challenge to develop an effective voltage-regulation method using a straightforward implementation. This paper proposes a novel method for local voltage control and balancing using a shunt-connected energy storage system. The compensation principles are explained, and a complete controller design is proposed. The algorithm is designed to be implemented in power electronic converters that provide the interface between the storage and the grid. The original contribution is the development of a low-level control method, which includes voltage balancing and a method to minimize the compensator current and is to be implemented in power electronic converters that provide the interface between the storage and the grid. The calculation of active and reactive compensator currents is explained with relation to the estimated grid impedance. The efficacy of the designed controller is verified by laboratory experiments. It is shown that voltage regulation using the proposed method is achieved with less apparent power compared to a system where only reactive power is used. The controller presents a very good dynamic response to rapid voltage variations, such as unbalanced voltage dips. The applicability and constraints of the method are discussed with respect to the present state of the art in low-voltage-grid voltage regulation.

This paper investigates component minimized topology of single-phase to three-phase AC/DC/AC pulse width modulated (PWM) converter. It consists of half-bridge rectifier and two-leg (B4) inverter and is designed for low-power induction machine (IM) drive application. Effect of voltage imbalance between split capacitor bank is discussed and improved control algorithm is proposed to minimize imbalance and compensate its impact on output power quality. Proposed method is verified experimentally with 3 kW model.