Mahmoud M. Amin

Development of High-Performance Grid-Connected Wind Energy Conversion System for Optimum Utilization of Variable Speed Wind Turbines

This paper presents an improvement technique for the power quality of the electrical part of a wind generation system with a self-excited induction generator (SEIG) which aims to optimize the utilization of wind power injected into weak grids. To realize this goal, an uncontrolled rectifier-digitally controlled inverter system is proposed. The advantage of the proposed system is its simplicity due to fewer controlled switches which leads to less control complexity. It also provides full control of active and reactive power injected into the grid using a voltage source inverter (VSI) as a dynamic volt ampere reactive (VAR) compensator. A voltage oriented control (VOC) scheme is presented in order to control the energy to be injected into the grid. In an attempt to minimize the harmonics in the inverter current and voltage and to avoid poor power quality of the wind energy conversion system (WECS), an LC filter is inserted between VOC VSI and the grid. The proposed technique is implemented by a digital signal processor (DSP TMS320F240) to verify the validity of the proposed model and show its practical superiority in renewable energy applications.

Vector oriented control of voltage source PWM inverter as a dynamic VAR compensator for wind energy conversion system connected to utility grid

This paper presents analysis, design, and simulation for vector oriented control of three-phase voltage source pulse-width modulation (PWM) inverter which aims to optimize the utilization of wind power injected into the grid. To realize this goal, a digitally controlled converter-inverter system is proposed which provides economic utilization of the wind generator by insuring unity power factor operation under different possible conditions, and full control of active and reactive power injected into the grid using a digitally controlled voltage source inverter. The wind energy conversion system (WECS) is represented by three -phase self-excited induction generator (SEIG) driven by a variable-speed prime mover (VSPM) such as a wind turbine for the clean alternative renewable energy in rural areas. Mathematical models for both the converter and inverter are presented and simulated. A vector oriented control scheme is presented in order to control the energy to be injected into the grid. Closed-loop control of the converter/inverter utilizes a conventional proportional integral (PI) controller. In order to examine the dynamic performance of the system, its model is simulated and results are analyzed. Simulation results for different disturbance conditions show good performance of this proposed control algorithm. The simulation results are given using MATLAB7/SIMULINK program. Experimental results using DSpace-1104 confirm that the good performance of the proposed control system and agree with the simulation results to a great extend.

DC-Bus Voltage Control Technique for Parallel-Integrated Permanent Magnet Wind Generation Systems

Summary form only given. This paper presents a dc-bus voltage control technique for a new power conversion topology feasible for parallel-integrated permanent magnet wind generation systems. This technique is based on a master-slave hysteresis control scheme in order to solve discrepancy problems that could happen between the controllers. A three-phase semi-controlled rectifier topology is proposed here as an effective interface circuit between each wind generator and the dc-bus. The proposed system provides interconnection extension ability of multi wind converter units sharing the same dc-bus and more economic utilization of the wind generator; by insuring unity power factor operation. More advantages include voltage disturbance compensation capability, robustness; since a short circuit through a leg is not possible and high efficiency; due to the reduced number of switching elements. The rectifier topology concept, the principle of operation, the control scheme and test results are presented. The developed technique is also implemented on a 12 kW parallel-connected permanent magnet laboratory setup in order to confirm the effectiveness of the proposed system.

DC bus voltage control for PV sources in a DC distribution system infrastructure

This paper proposes a design of a controlled voltage bus for a PV source to be used in a hybrid DC distribution system infrastructure. Load centers, boost converter, and distribution panels combine to link the solar collectors with multiple loads and Backup battery systems add to the complexity of a PV installation. The controlled voltage bus is constructed based on the design of a DC-DC boost converter. A Traditional DC-DC boost converter is limited to get a constant DC voltage as an input and boosting it to a certain voltage level as long as the load is fixed. The boost converter described in this paper is capable of receiving variable DC voltage as an input and give a constant boosted DC output voltage. The significant advantage of this device is that it is capable of producing a fixed voltage, with a very small ripple that can be neglected, while operating with variable load. The parameters of the DC-DC boost circuit were calculated such that it gives the device the ability of controlling a wide range of input voltage and be operated at a wide range of load variations. Closed-loop control of the boost converter utilizes a conventional proportional integral (PI) controller. Since the system has two variables which are the input voltage and the load, the duty ratio is not allowed to be constant to get a fixed output voltage. The PI controller is used in a closed loop system to obtain a suitable duty cycle to keep the output voltage constant according to the reference level of the DC-bus. Simulation and experimental results for different disturbance conditions show good performance of this proposed control system. The results verify the validity of the proposed model and show its practical use in renewable energy applications.

Development of a grid-connected wind generation system utilizing high frequency-based three-phase semicontrolled rectifier-current source inverter

In this paper, a high frequency (HF)-based three-phase Semicontrolled rectifier-current source inverter system is proposed for grid-connected permanent magnet wind generators. The main advantages of the topology are: high efficiency due to less power losses and reduced number of switching elements, high output power density realization, reduced passive component ratings proportionally to the frequency, robustness, as short-circuit through a leg is not possible, and harmonics are of higher orders and are easily filtered out. As a disadvantage, higher but acceptable total harmonic distortion of the generator currents is introduced. A maximum power point tracking (MPPT) algorithm is achieved through a hysteresis control for the rectifier operation. Additionally, a sinusoidal pulse width modulation (SPWM) three phase current source inverter (CSI) is also employed in the grid connection. The complete operation of the rectifier-inverter and theoretical analysis are presented. Test results on 5-kW wind generation system are presented and discussed to confirm the effectiveness of the proposed topology for grid connected systems.

Design and implementation of dc-bus system module for parallel integrated sustainable energy conversion systems

In this paper, a performance analysis of a highly integrated, high-performance dc-bus system module is presented. This module introduces a solution for medium & low voltage DC distribution applications. It is designed for applications requiring a single bus solution to control up to twelve DC-sources sharing same dc-bus and having same dc-voltage level. The bus is also designed to interface with various power converter modules. Moreover, it has ability for parallel integrated renewable sources connection representing DC-microgrid. A master-slave dc-bus voltage control technique for parallel wind-based synchronous generators is introduced. This technique is developed based on the voltage oriented control (VOC) algorithm for PWM converters. Test results for different disturbance conditions are carried out to validate this developed module. The proposed system is also implemented in a laboratory setup which includes two synchronous generators (250 W, 2.2 kW) each driven by a variable speed prime mover (VSPM) to emulate a wind turbine behavior, two 3-phase PWM based converters, 3-phase line inductors connected between wind generators and converters, variable resistive DC-load, and a digital signal processor (DSP TMS320F240). The experimental results confirm the validity of the developed module for parallel integrated sustainable energy conversion systems.

A Three-Phase High Frequency Semi-Controlled Battery Charging Power Converter for Plug-In Hybrid Electric Vehicles

This paper presents a novel analysis, design, and implementation of a battery charging three-phase high frequency semicontrolled power converter feasible for plug-in hybrid electric vehicles. The main advantages of the proposed topology include high efficiency; due to lower power losses and reduced number of switching elements, high output power density realization, and reduced passive component ratings proportionally to the frequency. Additional advantages also include grid economic utilization by insuring unity power factor operation under different possible conditions and robustness since short-circuit through a leg is not possible. A high but acceptable total harmonic distortion of the generator currents is introduced in the proposed topology which can be viewed as a minor disadvantage when compared to traditional boost rectifiers. A hysteresis control algorithm is proposed to achieve lower current harmonic distortion for the rectifier operation. The rectifier topology concept, the principle of operation, and control scheme are presented. Additionally, a dc-dc converter is also employed in the rectifier-battery connection. Test results on 50-㎑ power converter system are presented and discussed to confirm the effectiveness of the proposed topology for PHEV applications.

Development of a Wide Area Measurement System for Smart Grid Applications

Abstract In this paper, the modeling for a complete scenario of a proposed wide area measurement system (WAMS) based on synchronized phasor measurement units (PMUs) technology with the access of a broadband communication capability is presented. The purpose is to increase the overall system efficiency and reliability for all power stages via significant dependence on WAMS as distributed intelligence agents with improved monitoring, protection, and control capabilities of power networks. The developed system is simulated using the Matlab/Simulink program. The power system layer consists of a 50 kW generation station, 20 kW wind turbine, three transformers, four circuit breakers, four buses, two short transmission lines, and two 30 kW loads. The communication layer consists of three PMUs, located at generation and load buses, and one phasor data concentrator (PDC), that will collect the data received from remote PMUs and send it to the control center for analysis and control actions. The proposed system is tested under two possible cases; normal operation and fault state. It was found that power system status can be easily monitored and controlled in real time by using the measured bus values online which improves the overall system reliability and avoids cascaded blackout during fault occurrence. The simulation results confirm the validity of the proposed WAMS technology for smart grid applications.

Power quality improvement of grid-connected wind energy conversion system for optimum utilization of variable speed wind turbines

This paper presents an improved technique for the power quality of the electrical part of a wind generation system with a synchronous generator (SG). The main aim is to optimize the utilization of wind power injected into the grid. To realize this goal, an uncontrolled rectifier-digitally controlled inverter (URDCI) system is proposed. The advantage of the proposed system is its simplicity due to reduced number of controlled switches which leads to less control complexity. The inverter system provides economic utilization of the wind generator by insuring unity power factor operation under different possible conditions. It also provides full control of active and reactive power injected into the grid using a digitally controlled voltage source inverter (VSI). A voltage oriented control (VOC) scheme is presented in order to control the energy to be injected into the grid. In an attempt to minimize the harmonics in the inverter current and voltage and to avoid poor power quality of the wind energy conversion system (WECS), an LC filter is inserted between VOC VSI and the grid. Simulation results are carried out to validate the proposed solution. The proposed technique is implemented by a digital signal processor (DSP TMS320F240) to verify the good performance of the proposed control system and agree with the simulation results to a great extend. The results verify the validity of the proposed model and show its practical superiority in renewable energy applications.

A novel grid-connected multi-input boost converter for HEVs: Design and implementation

In plug-in hybrid electric vehicles, multi-input boost converters became widely used to enhance the stability and reliability. However, conventional boost converters have difficulty of low efficiency and the implementation size problem as well as the cost. To improve these drawbacks, this paper proposes a novel modularized multi-input bridgeless boost converter that interfaces the hybrid AC/DC power sources to the vehicle power train. In this study, the multi-input structure with bridgeless high frequency boost converter is proposed in order to reduce the size of the passive components with high efficiency compared to other topologies. The proposed topology is compared with bridge boost converter and Bridgeless power factor correction converter topologies in order to examine its performances. The converter topologies and their controller are designed and investigated. Furthermore, the proposed topology is experimentally validated with results obtained from 60-kW prototype that has been built and tested in our laboratory based on TMS320F28335 DSP. The results have demonstrated that the proposed topology is more efficient than other converter topologies to achieve great size reduction with high performance.