This paper presents the detailed design, analysis, and application of the controller for a shunt active power filter based on a pulsewidth modulation dc-to-ac voltage source converter. The controller is mainly tailored to compensate harmonic currents of nonlinear loads connected to the mains. However, it can also achieve reactive-power compensation and mains-current balancing when required. The controller has a two-layer structure. The outer layer generates the current references for the inner layer. The former uses a plug-in discrete-time repetitive algorithm for current-harmonic compensation, a proportional-integral algorithm to maintain the dc-capacitor voltage in spite of unmodeled losses and a reactive-power-reference generator. The inner layer uses state-feedback with integral action for current control. The repetitive controller is justified to improve the tracking of the periodic current references required by the active filters. The stability of the resulting closed-loop system is studied and some indication of the system robustness is given. The proposed controller has been tested in a prototype with balanced and unbalanced nonlinear loads. A discrete-time model of the filter has been used from the beginning. The microcomputer delay when calculating the controller output and the delay due to the anti-aliasing filters have been included in the inner system state-variable model

This paper presents a control system based on a repetitive controller to compensate for key power-quality disturbances, namely voltage sags, harmonic voltages, and voltage imbalances, using a dynamic voltage restorer (DVR). The control scheme deals with all three disturbances simultaneously within a bandwidth. The control structure is quite simple and yet very robust; it contains a feedforward term to improve the transient response and a feedback term to enable zero error in steady state. The well-developed graphical facilities available in PSCAD/EMTDC are used to carry out all modeling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation.

This paper presents the control system based on the so-called repetitive control for a five-level flying-capacitor dynamic voltage restorer (DVR). This DVR multilevel topology is suitable for medium-voltage applications and operated by the control scheme developed in this paper. It is able to mitigate power-quality disturbances, such as voltage sags, harmonic voltages, and voltage imbalances simultaneously within a bandwidth. The control structure has been divided into three subsystems; the first one improves the transient response of the filter used to eliminate the modulation high-frequency harmonics, the second one deals with the load voltage; and the third is charged with maintaining balanced voltages in the flying capacitors. The well-developed graphical facilities available in PSCAD/EMTDC are used to carry out all modelling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation.

The design, construction and evaluation of a contactless battery charger for electric vehicles (EVs) based on inductive power transfer (IPT) is presented in this study. The design of such systems entails a high degree of complexity because of the large number of design parameters involved and, consequently, trade‐offs in selecting the key design parameters have to be established. The design process and selection of the IPT system parameters is detailed in this study, considering the most common specifications of EV chargers and the practical issues of the implementation. Regarding the compensation scheme, which is one of the main issues in the design, series compensation in both the primary and secondary has been adopted because of the advantages identified after a comprehensive analysis. A laboratory prototype has been built and tested, providing extensive results of the system performance in terms of efficiency and power transfer capability, considering load power variations, as well as changes in the air gap between coils. A detailed analysis of the efficiency of each stage in the IPT system and their contribution to the overall efficiency is also provided.

This paper studies the economic dispatch problem for a microgrid that interacts with external agents. First, the microgrid acts in the day-ahead market in order to find the optimal schedule for its internal resources, considering the consumption and generation forecast and the energy price prediction. Once the day-ahead market has closed, external agents such as other microgrids in the same network, aggregators or electric vehicles can interact with the microgrid through a local energy market. If an external agent requests a specific energy profile that offers an economic benefit, the microgrid controller will propose supplying the closest profile to that requested, depending on the benefit offered. The proposed solution allows the microgrid to respond to external requests, thus optimizing its economic benefit. The problem is solved using Model Predictive Control (MPC), and the operation and degradation costs are included in the objective function. In order to capture both continuous/discrete dynamics and switching between different operating conditions, the plant is modeled using the Mixed Logic Dynamic (MLD) framework. The MPC problem is solved by means of mixed-integer quadratic programming (MIQP).