“Shunt Filtering Techniques for Steady-State and Dynamic Harmonic Mitigatio and Reactive Power Compensation in Power Systems”

The research work presented in this thesis is focused in the shunt filtering techniques to mitigate harmonic distortion and compensate reactive power in electric systems. Among the different alternatives and devices available, the attention is centered in the shunt Active Power Filter, Shunt Hybrid Filter and the Active Power Line Conditioner for compensation of reactive power and/or mitigation of harmonic currents in electric systems. The Active Power Filter has proved to be an efficient alternative due to its well known capabilities to perform harmonic distortion and reactive power compensation. Nevertheless, the research field is very active in the development of control algorithms for determining the reference signals of compensation. In this thesis, a control algorithm in phase coordinates, able to handle steady-state and dynamic compensation, has been developed and implemented in Matlab/Simulink®. In order to validate a future physical implementation of the compensation device, the control algorithm to determine the reference signals, as well as the complete model of the shunt APF, has been tested with Real-Time simulations to validate the feasibility of the control algorithm affordable computational demand. The real-time simulations include both steady-state and dynamic compensation of nonlinear loads. Following the aim of taking into account practical considerations of the compensation scheme, the Shunt Hybrid Filter is presented by adding a shunt capacitor to the compensation scheme. The shunt capacitor is placed to compensate reactive power, which reduces the necessary rating of the more expensive active power filter device, and can be used as a high-pass filter for draining-out the ripple current of commutation. To achieve this goal properly, a Linear Quadratic Regulator switching current controller has been designed to avoid undesirable/possible parallel resonance effects. Finally, for the case of harmonic control in distribution power systems, a novel alternative in the Active Power Line Conditioner planning has been fully developed. The proposed alternative is formulated by considering the Individual Harmonic Distortion and Total Harmonic Distortion indices at all buses of the distribution power system. This new proposal in the Active Power Line Conditioner planning has the aim of reducing the necessary control demand. Since each one of the considered Active Power Line Conditioners are injecting only a single harmonic frequency as a corrective measure, the optimization based method to determine the injection currents is found to have a lower computational demand. In addition, the best location for the single-harmonic Active Power Line Conditioners is determined by using a sensitivity analysis, and the injection currents are determined by solving a convex optimization problem