Paulo Sergio Nascimento Filho

Design methodology of P-res controllers with harmonic compensation for three-phase DC-AC grid-tie inverters with LCL output filter

This paper describes the modeling, control and operation of a grid-tie DC-AC inverter with LCL output filter. The proposed control system mitigates the impact caused by grid harmonic voltages. A current control approach with active damping based on the P-resonant controller with a cascaded notch filter is analyzed. In this approach the aim is to mitigate the effects of the resonance peak of the LCL filter and mains harmonics on the operation of the converter and on the quality of the electrical current injected into the power grid. The proposed P-resonant controller is designed and its parameters are obtained with an analytical methodology based on frequency response.

An Approach for Switched Reluctance Generator in a Wind Generation System With a Wide Range of Operation Speed

This paper presents a complete approach for switched reluctance generator (SRG) in variable wind energy conversion systems. Two forms of direct power control (DPC) and a commutative system that allows SRG performance at a wide range of speed variations are proposed. Thus, more mechanical energy can be captured in wind generation. In the proposed structure, the SRG operates in a self-excited mode using a common dc bus system of a voltage source inverter connected to an electrical grid. DPCs are proposed by hysteresis of the SRG phase current for low-speed operation (DPC-LS) and by a single pulse of current for high-speed operation (DPC-HS). The low-pass filter employed to obtain the average power generated may slow down the response of the control system of the DPC applied to SRG. To improve the system performance, sliding mode controllers in DPCs were used. For operation throughout a wide speed range, the DPC-LS and DPC-HS controls should be joined. Therefore, a commutative system with smooth transition between DPC modes is proposed. Finally, simulations and experimental tests were conducted to verify the behavior of the proposed arrangement. The results confirmed correct operation of the proposed system.

Strategy for modeling a 3-phase grid-tie VSC with LCL filter and controlling the DC-link voltage and output current considering the filter dynamics

This work presents an analytical and detailed design methodology of the output current controller and DC link voltage controller of the three-phase VSC (voltage source converter) with output LCL filter. Most of inverter-based grid-tie systems use L filters, which present structural simplicity and are easy for modeling and controlling. However, the 3rd order LCL filter mitigates switching harmonic currents and increases bandwidth. Despite its advantages, the LCL filter introduces a resonant peak and reduces damping. This problem can be addressed with active damping techniques. This paper presents an accurate modeling and controlling analysis of the grid-tie VSC taking into account the influence of the dynamic behavior of the LCL filter.

Modeling and digital control of a high-power full-bridge isolated DC-DC buck converter designed for a two-stage grid-tie PV inverter

This paper describes a grid-tie photovoltaic (PV) inverter composed of an isolated full-bridge buck DC-DC converter with high-frequency transformer and a cascaded DC-AC full-bridge inverter connected to the grid. Emphasis is given on the modeling and digital control design of the DC-DC converter with the polynomial pole placement method. Simulation results are presented and a inverter prototype is currently being built.

Input voltage regulation of an isolated full-bridge boost converter fed by a photovoltaic device with the state-space feedback control method

This paper presents the modeling and control design of an isolated full-bridge boost converter fed by a photovoltaic (PV) device. The converter and PV device are modeled using the method of average state variables and the controller is designed with the statespace feedback control technique, using concepts of characteristic polynomial, controllability and Ackermans matrix. The dynamic model of the converter is obtained and the voltage controller is designed in order to achieve the regulation of the input voltage of the boost converter, thus allowing the direct control of the PV voltage, which brings advantages when this system is compared to traditional control strategies for grid-tie PV converters. The modeling strategy and the controller design are carefully presented and simulation results obtained with Matlab/Simulink are presented.