Marek Jasinski

Simple direct power control of three-phase PWM rectifier using space-vector modulation (DPC-SVM)

This paper proposes a novel and simple direct power control of three-phase pulsewidth-modulated (PWM) rectifiers with constant switching frequency using space-vector modulation (DPC-SVM). The active and reactive powers are used as the pulse width modulated (PWM) control variables instead of the three-phase line currents being used. Moreover, line voltage sensors are replaced by a virtual flux estimator. The theoretical principle of this method is discussed. The steady-state and dynamic results of DPC-SVM that illustrate the operation and performance of the proposed system are presented. It is shown that DPC-SVM exhibits several features, such as a simple algorithm, good dynamic response, constant switching frequency, and particularly it provides sinusoidal line current when supply voltage is not ideal. Results have proven excellent performance and verify the validity of the proposed system.

DSP-Based Control of Grid-Connected Power Converters Operating Under Grid Distortions

Power electronic Grid-Connected Converters (GCCs) are widely applied as grid interface in renewable energy sources. This paper proposes an extended Direct Power Control with Space Vector Modulation (DPC-SVM) scheme with improved operation performance under grid distortions. The real-time operated DPC-SVM scheme has to execute several important tasks as: space vector pulse width modulation, active and reactive power feedback control, grid current harmonics and voltage dips compensation. Thus, development and implementation of the DPC-SVM algorithm using single chip floating-point microcontroller TMS320F28335 is described. It combines large peripheral equipment, typical for microcontrollers, with high computation capacity characteristic for Digital Signal Processors (DSPs). The novelty of the proposed system lies in extension of the generic DPC-SVM scheme by additional higher harmonic and voltage dips compensation modules and implementation of the whole algorithm in a single chip floating point microcontroller. Overview of the laboratory setup, description of basic algorithm subtasks sequence, software optimization as well as execution time of specific program modules on fixed-point and floating-point processors are discussed. Selected oscillograms illustrating operation and robustness of the developed algorithm used in 5 kVA laboratory model of the GCC are presented.

Renewable Energy Operation and Conversion Schemes: A Summary of Discussions During the Seminar on Renewable Energy Systems

A short summary of some speeches given during Seminar on Renewable Energy system (SERENE) is presented. The contributions have been mainly focused on power electronics for photovoltaic (PV) and sea wave energies, pointing out some aspects related to efficiency, reliability, and grid integration. Finally, main issues concerning fuel cell (FC) systems as generators based on hydrogen as a low environmental impact energy vector are presented.

Fuzzy logic current controller for PWM rectifiers

In this paper a comparison between fuzzy logic current controller (FLC) and classical PI current controller for a LCL-filter based PWM rectifier is presented. Both simulations and experimental results are included. The current control of PWM rectifiers is implemented in voltage oriented coordinates, known as voltage oriented control (VOC). This paper also presents design process of the fuzzy logic controller based on well-known proportional-integral current controller made by backward rule. The simulations (Matlab/sup TM/, Simulink/sup TM/) of the current controllers are performed in model of the existing laboratory setup. The paper shows the step-response of the i/sub d/ current for conventional PI-controller and the proposed FLC which provides good tracking of the reference current waveform with smaller overshoot in transient for the same step in U/sub DC/.

Power electronics for renewable sea wave energy

This paper has an objective to combine and disseminate information on sea wave energy converters. The potential of sea wave energy is very high and over one thousands patents exists, however, only selected projects supported by EC are presented. At the beginning a basic terms and methods of sea wave energy capture are discussed. Further several most important sea wave energy conversion prototypes are shown. The generators and power electronics solutions for Power Take Off system are presented on the example of Wave Dragon MW sea wave energy converter. The Wave Dragon MW captures power from the sea waves by means of low-head turbines and converts it into rotating mechanical power. Problems which can appear in mechanical power to electrical power conversion in Wave Dragon MW can be expected to be similar as in wind turbine. However, subject of the mechanical energy conversion from sea waves to electrical energy is not well identified and further research should be curried out. Additionally, specific problems of grid connected AC-DC-AC converters under grid voltage distortions (harmonics and voltage dips) are discussed. Some simulated and experimental oscillograms that illustrate properties of the presented systems are shown.

Control of AC/DC/AC Converter for Multi MW Wave Dragon Offshore Energy Conversion System

In the paper a direct power and torque control-space vector modulated (DPTC-SVM) algorithm for AC/DC/AC converter is presented. This strategy leads to good dynamic and static behaviors. Additional power feedforward (PF) loop from a generator side converter (GSC) to line side converter (LSC) control improves dynamic of the power flow. As a result, more accurate input-output energy matching allows better stabilization of DC-link voltage. Hence, life time of DC-link capacitors would be prolonged. Moreover, proposed advanced control strategy gives possibility of control in whole power range of active and reactive power injected to the line. Line current has sinusoidal waveform with THD bellow 5% in all operation modes. Presented AC/DC/AC converter with permanent magnet synchronous generator (PMSG) system is considered to be implemented in wave energy converter - Wave Dragon MW [1].

Novel sensorless direct power and torque control of space vector modulated ac/dc/ac converter

A novel control strategy for PWM rectifier-inverter system is proposed. Fast controls strategies such as line voltage sensorless virtual flux (VF) based direct power-control with space vector modulator (DPC-SVM) for rectifier and direct torque control with space vector modulator (DTC-SVM) for inverter side are used. These strategies lead to good dynamic and static behaviour of the proposed control system- direct power and torque control- space vector modulated (DPT-SVM). The results obtained in simulations and experiment show good performance of the proposed system. Additional power loop from motor to PWM rectifier side improved dynamic behaviors of the power flow control. As result, better input-output energy matching allows decreasing the size of the dc-link capacitor.

Grid connection of multi-Megawatt clean Wave energy power plant under weak grid condition

The WaveDragon is a 7 megawatt wave energy converter, that is currently developed for clean offshore energy production. The system will be floating several kilometres off the Pembrokeshire coast, Wales, UK, and transfers energy using a submarine power cable. Key interest is the control of the power take-off system at disturbed voltages and under weak-grid condition due to long submarine cable and remote, rural location. A multi-reference frame controller is implemented for harmonics compensation. A parameter estimator is implemented to estimate the grid impedance. Simulation and measurements results from a laboratory test setup that illustrate properties of developed method are shown.

Brief view on control of grid‐interfacing AC‐DC‐AC converter and active filter under unbalanced and distorted voltage conditions

Purpose – The purpose of this paper is to consider both sides of a back‐to‐back AC‐DC‐AC interface.Design/methodology/approach – The paper presents a mathematical analysis, simulation, laboratory test in scaled model.Findings – The two main findings comprised concept of control methods for grid AC‐DC‐AC converter applied in renewable energy sources with variable speed operation under distorted grid. Active filtering functionality in case of non‐linear current of a parallel load. Second, a control algorithm dedicated for two‐level AC‐DC converter applied in industrial networks with high‐order harmonics compensation working under hard conditions – balanced and unbalanced voltage dips.Research limitations/implications – The paper shows preliminary results for AC‐DC‐AC converter and active filter (AF) during voltage dips and for harmonics compensation. Control methods and/or topology should be improved and tested in scale and after at high‐power system.Practical implications – Power quality supplied/received ...

Sensorless direct power and torque control of PWM back-to-back converter-fed induction motor

A novel control scheme for PWM rectifier-inverter system is proposed. Fast control strategies such as line voltage sensorless virtual flux (VF) based direct power control with space vector modulator (DPC-SVM) for PWM rectifier and direct torque control with space vector modulator (DTC-SVM) for PWM inverter side are used. These strategies lead to good dynamic and static behaviors of the proposed control system-direct power and torque control-space vector modulated (DPT-SVM). Simulations and experiment results obtained show good performances of the proposed system. Additional power feedforward loop from a motor to PWM rectifier control side improved dynamic behaviors of the power flow control. As a result, better input-output energy matching allows decreasing the size of the DC-link capacitor.