Ernesto Ruppert

A Deadbeat Active and Reactive Power Control for Doubly Fed Induction Generator

Abstract This article proposes a power control scheme for doubly fed induction generator for variable speed wind power generation. This scheme uses a deadbeat control loop. The algorithm of the deadbeat calculates at each sample period the voltage vector to be supplied to the rotor in order to guarantee that the active and reactive power reach their desired reference values. The robustness of the controller against rotor resistance variation was evaluated. Simulations results are carried out for validation of the digital controller operation.

MODELING AND CONTROL OF A THREE-PHASE ISOLATED GRID-CONNECTED CONVERTER FOR PHOTOVOLTAIC APPLICATIONS

This paper describes the modeling and control of a three-phase grid-connected converter fed by a photovoltaic array. The converter is composed of an isolated DC-DC converter and a three-phase DC-AC voltage source inverter The converters are modeled in order to obtain small-signal transfer functions that are used in the design of three closed-loop controllers: for the output voltage of the PV array, the DC link voltage and the output currents. Simulated and experimental results are presented.

Modeling of PV module with consideration of environmental factors

This paper discusses the modeling of single-diode photovoltaic cell to estimate the maximum power with respect to changes in environmental factors that effects its efficiency performance. The parameters, i.e. resistances for the modeling of PV cell are determined for nonlinear I-V characteristics to replicate the maximum power point. These values are determined at various environmental factors like; dust, solar radiation intensity, shadow, temperature and wind velocity.

Simulation of PV array output power for modified PV cell model

This paper discusses the performance of a PV system which uses a PV cell modeled with basis on the maximum power point characteristics. The results are simulated for a typical daily variation of solar radiation. The effect of temperature on the system output is also simulated.

Micro-inverter for integrated grid-tie PV module using resonant controller

Two-stage isolated converters for photovoltaic (PV) applications commonly employ a high-frequency transformer on the DC-DC side, submitting the DC-AC inverter switches to high voltages and forcing the use of IGBTs instead of low-voltage and low-loss MOSFETs. This paper shows the modeling, control and simulation of a single-phase full-bridge inverter with high-frequency transformer (HFT) that can be used as part of a two-stage converter with transformerless DC-DC side or as a single-stage converter (simple DC-AC inverter) for grid-connected PV applications. The inverter is modeled in order to obtain a small-signal transfer function used to design the P+Resonant current control regulator. A high-frequency step-up transformer results in reduced voltage switches and better efficiency compared with converters in which the transformer is used on the DC-DC side. Simulations and experimental results with a 200 W prototype are shown.

Resonant (P+RES) controller applied to voltage source inverter with minimum DC link capacitor

Voltage source inverters use large electrolytic capacitors in order to decouple the energy between the utility and the load, keeping the DC link voltage constant. Decreasing the capacitance reduces the distortion in the inverter input current but this also affects the load with low-order harmonics and generate disturbances at the input voltage. This paper applies the P+RES controller to solve the challenge of regulating the output current by means of controlling the magnitude of the current space vector, keeping it constant thus rejecting harmonic disturbances that would otherwise propagate to the load. This work presents a discussion of the switching and control strategy.

Three-phase induction motor DTC-SVM scheme with Self-Tuning PI-Type Fuzzy controller

The Direct Torque Control (DTC) with Space Vector Modulation (SVM) and Self-Tuning PI-Type Fuzzy (STPIF) controller is proposed. This controller determines dynamically the load angle between stator and rotor flux vectors and in consequence the electromagnetic torque necessary to supply the motor load. The rule base for STPIF controller is defined in function of the error “e” and the change of the error “Δe” of the torque using a most natural and unbiased membership functions (MF). Constant switching frequency and low torque ripple are obtained using SVM. Performance of the proposed DTC-SVM with STPIF are compared with the performance of the same scheme but using PI controller in terms of several performance measures such as settling time, rise time and integral-of-time multiplied by the absolute magnitude of the error index (ITAE). The simulation results show that the proposed scheme can ensure fast torque response and low torque ripple in comparison with DTC-SVM with PI controller.

A wind energy generator for smart grid applications using wireless-coded neuro-fuzzy power control

Wind energy is the major driver to obtain an optimized and efficient use of renewable energy in smart grids. To provide balanced supply, demand, and storage of energy in a much more efficient manner than is done today, smart grids require the employment of an advanced communication infrastructure associated to a robust power control and real-time monitoring systems.Towards this objective, we present a wireless-coded power control scheme for doubly fed induction generators operating at variable speed. The proposed system employs adaptive neuro-fuzzy control, quaternary phase shift-keying modulation, and low-density parity check coding techniques to improve the system robustness and reliability in different propagation conditions for remotely transmitting the power control references from the control center to a given aerogenerator.

Comparative analysis of current and voltage-controlled photovoltaic Maximum Power Point tracking

Maximum Power Point tracking (MPPT) in photovoltaic (PV) systems may be achieved by controlling either the voltage or current of the PV device. There is no consensus in the technical literature about how is the best choice. This paper provides a comparative analysis performance among current and voltage control using two different MPPT strategies: the perturb and observe (P&O) and the incremental conductance techniques.

On the synchronous generator parameters determination using dynamic simulations based on IEEE standards

This paper shows, through simulations using the software Matlab/Simulink and its library Simpowersystems, how to perform the synchronous generator load rejection tests and how to obtain the values of the synchronous generator electrical operational parameters which are important data to perform generator and electrical power system dynamic studies. The paper discuss the d-axis load rejection test, the q-axis load rejection test, the arbitrary axis load rejection test also shows how to calculate the electrical fundamental parameters which characterizes the synchronous generator.