This paper shows a new algorithm in the natural coordinates to calculate the current reference in a shunt active power filter. It modifies the Fryze's algorithm based on classical power theories for obtaining an optimal estimation in the current reference when the voltage in the utility is distorted. The aim of the method is twofold; first, to mitigate the harmonic components and second, to improve the power factor in the system blocking the reactive components. The feasibility of the algorithm in real-time applications has been tested with different waveforms and the results are compared by means of the total harmonic distortion in the grid current and the system power factor before and after the compensation. In addition, the results obtained in the experimental setup show the correct performance of the algorithm and demonstrate its easy implementation in industrial systems.

A Model Predictive Control (MPC) strategy based on the Evolutionary Algorithms (EA) is proposed for the optimal dispatch of renewable generation units and demand response in a grid-tied hybrid system. The generating system is based on the experimental setup installed in a Distributed Energy Resources Laboratory (LabDER), which includes an AC micro-grid with small scale PV/Wind/Biomass systems. Energy storage is by lead-acid batteries and an H2 system (electrolyzer, H2 cylinders and Fuel Cell). The energy demand is residential in nature, consisting of a base load plus others that can be disconnected or moved to other times of the day within a demand response program. Based on the experimental data from each of the LabDER renewable generation and storage systems, a micro-grid operating model was developed in MATLAB © to simulate energy flows and their interaction with the grid. The proposed optimization algorithm seeks the minimum hourly cost of the energy consumed by the demand and the maximum use of renewable resources, using the minimum computational resources. The simulation results of the experimental micro-grid are given with seasonal data and the benefits of using the algorithm are pointed out.

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This paper shows a new strategy to calculate the reference current in a power active filter used to mitigate harmonics injected by non-linear loads. The current is predicted with a Kalman filter a sampling period ahead to reduce and compensate the delay time effects caused by the acquisition times, the data processing and the performance of the filter. The validity of the algorithm is demonstrated by means of simulations in Matlab/Simulink. Several Kalman filters were studied and their capabilities compared to find out the best performance at the lowest computational cost.