Andreas Sumper

Ride-Through Control of a Doubly Fed Induction Generator Under Unbalanced Voltage Sags

This paper deals with the control of doubly fed induction generators to ride through unbalanced voltage sags. A control strategy is proposed by choosing certain current reference values in the positive and negative sequences so that the torque and the DC voltage are kept stable during such unbalanced sags. Both rotor- and grid-side converters are considered, detailing the control scheme of each converter while considering the effect of the crowbar protection. The control strategy is validated by means of simulations.

A distance PLC programming course employing a remote laboratory based on a flexible manufacturing cell

The increasing necessity of engineers capable of handling the problems of the industry and able to face the technical challenges they will encounter in their professional career is boosting the teaching methods based on projects and real applications. The Center of Technological Innovation in Static Converters and Drives, Technical University of Catalonia (CITCEA-UPC) group, Barcelona, Spain, has introduced such learning methods applied to the automation field in a course taught for the electrical engineering degree and in some postgraduate workshops, making the laboratory platforms available through the Internet in order to allow the use of such practices in e-learning-based courses. The learning method is based on a flexible manufacturing cell, resulting from the collaboration between the CITCEA-UPC and Schneider Electric and its Training Center. The problem proposed to the students is the automation of such a cell with commercial programmable logic controllers (PLCs). The experience has proved to be positive, and the students have valued it accordingly

Response of Fixed Speed Wind Turbines to System Frequency Disturbances

This paper analyzes the impact of system frequency variations on the steady-state operation point of fixed speed induction generators used in wind turbine generation systems (WTGS). An analytic method to predict the values of angular speed, torque and current during and after a frequency disturbance is presented. The proposed method as well permits to establish the operation limits in order to keep the WTGS connected during frequency variations and therefore to adjust protection relay settings.

Modeling and control of the doubly fed induction generator wind turbine

The present paper deals with the modeling of wind turbine generation systems. The model of a doubly fed induction generator, along with the corresponding converter, crow bar protection and electrical grid is described. The different level control strategies both in normal operation and under voltage dig conditions are discussed, including speed control, torque and reactive power control for the rotor-side converter, reactive and DC voltage control for the grid-side converter and the corresponding current loops control. The results obtained with simulations are compared to experimental data obtained from voltage sags provoked to real wind turbines.

Control of a Wind Farm Based on Synchronous Generators With a Central HVDC-VSC Converter

A control scheme for wind farms based on synchronous generators connected to a single power converter is presented. The scheme is applicable to HVDC interfaced offshore or remote wind farms. The proposed control scheme is based on computing the optimal wind farm electrical frequency depending on the different incoming wind speeds. The power converter regulates the system frequency by adjusting the power injected to the HVDC circuit. Fault ride-through is also possible by reducing rapidly the injected active power. The proposed scheme is validated by means of simulations with a wind farm composed of four wind turbines.

Control of a Flywheel Energy Storage System for Power Smoothing in Wind Power Plants

This paper deals with the design and the experimental validation in scale-lab test benches of an energy management algorithm based on feedback control techniques for a flywheel energy storage device. The aim of the flywheel is to smooth the net power injected to the grid by a wind turbine or by a wind power plant. In particular, the objective is to compensate the power disturbances produced by the cycling torque disturbances of the wind turbines due to the airflow deviation through its tower section. This paper describes the control design, its tuning, as well as the description of the experimental setup, and the methods for the experimental validation of the proposed concepts. Results show that the fast wind power fluctuations can be mostly compensated through the flywheel support.

Experience on the implementation of a microgrid project in Barcelona

This paper deals with the implementation of a operating microgrid based on current real and emulated energy resources which permits the experimentation of various scenarios. This microgrid is able to adapt to different sorts of energy sources, loads and storage devices, and to critical situations that, with testing and emulation, can improve performances. The microgrid is implemented with real time data acquisition systems, communications (such as IEC 61850), and intelligent electronics peripheral equipment. Block diagrams, showing implementation using power electronics along with corresponding results, are shown for better understanding. Implementation and experimentation with the microgrid under investigation will improve future research on microgrid and smartgrid projects.

Electrical vehicles: State of art and issues for their connection to the network

The recent awareness about fossil fuels and the environment has arisen more sustainable alternatives regarding means of transport. The first alternative of green transport has been hybrid vehicles. This kind of vehicles reduces significantly the CO2 emission but not totally. Nowadays, the current trend is the utilization of a unique motor for vehicle. i.e. an electrical motor. It seems that the electric vehicles (EV) will become the cars of the future. Moreover, one kind of such vehicles, the plug-in electric vehicles (PHEV), will not only charge their batteries, but PHEV will also be able to inject power to the network when required. This fact suggests that EV penetration will affect current power system performance. Then, it is necessary to study some scenarios of penetration of such vehicles into the electrical network in order to maintain security and quality of power supply.

Frequency control of isolated wind and diesel hybrid MicroGrid power system by using fuzzy logic controllers and PID controllers

This paper presents a new application of fuzzy logic (FL) to1 an isolated network with a High Penetration, no-storage wind-diesel (HPNSWD) system. As a result of a study referring the behavior of an isolated electric system facing frequency disturbances, a fuzzy logic controller (FLC) was developed to improve the system´s dynamic performance. The validity of the proposed controller is evaluated by computer analysis using MATLAB/SIMULINK. The simulation results demonstrated that a small-scale wind turbine generation unit can be freely operated in an isolated distribution network without creating violation in power balance and voltage profile. The effectiveness of the fuzzy logic controller is then compared with that of a proportional-integral-and differential (PID) controller.

IEC 61850 as a flexible tool for electrical systems monitoring

In the last decades there have been great advances in electronic, information and communication technologies. Up to date, any of these advances have been implemented in electrical systems, but some difficulties have been encountered, particularly regarding to the integration of intelligent electronic devices from different manufactures into a centralized system. With the aim of solving the above mentioned problem, the standard IEO 61850 was developed to specify communication networks in substations. In addition to control and protection functions, the information model created around IEO 61850 series can help the development of other applications related with electrical monitoring systems. Monitoring can be used to achieve a variety of benefits for utilities, including maintenance prediction, failure prevention, active control, improved commissioning tests and more accurate end of life assessments. Examples of application that could be highly benefited by the adoption of IEC 61850 as standard for communications in the power electrical industry are power quality monitoring and condition based maintenance.In this paper, the new standard IEC61850 and the new opportunities that it can offer to the electrical industry are presented. Firstly, a brief presentation of IEC61850 and the main benefits it provides are described. Finally, a more detailed description of the possibilities that IEC61850 can offer in the field of power quality monitoring and condition based maintenance (CBM) is highlighted.