Application of STATCOM for improved dynamic performance of wind farms in a power grid

This thesis investigates the use of a Static Synchronous Compensator (STATCOM) along with wind farms for the purpose of stabilizing the grid voltage after grid-side disturbances such as a three phase short circuit fault, temporary trip of a wind turbine and sudden load changes. The strategy focuses on a fundamental grid operational requirement to maintain proper voltages at the point of common coupling by regulating voltage. The DC voltage at individual wind turbine (WT) inverters is also stabilized to facilitate continuous operation of wind turbines during disturbances --Abstract, page iii

Voltage Stability Enhancement of Wind Generator System Using Superconducting Fault Current Limiter

Wind generator systems have stability problems during network faults. The superconducting fault current limiter (SFCL) has the ability to prevent the magnitude of short-circuit current from increasing. This work proposes the SFCL device to enhance the voltage stability of a fixed-speed wind generator system.In this work the performance of SFCL is compared to that of the thyristor switched capacitor (TSC) method and the pitch control method. The comparison is done in terms of voltage stability enhancement, controller complexity and cost. The effectiveness of the proposed methodology is tested considering permanent and temporary, balanced and unbalanced faults in the power system model consisting of a wind generator and a synchronous generator.From the simulation results it is evident that performance of SFCL is better. On comparison it can be concluded that SFCL performs better when compared to TSC or pitch control method. Simulations are performed through Matlab/Simulink software

Power Quality Analysis of Offshore Wind Farms : Evaluating how different turbulence spectra will affect the power quality from offshore windsfarms using FAST, TurbSim and MATLAB/Simulink

Master's thesis in Renewable energy (ENE500

Wind Farm

During the last two decades, increase in electricity demand and environmental concern resulted in fast growth of power production from renewable sources. Wind power is one of the most efficient alternatives. Due to rapid development of wind turbine technology and increasing size of wind farms, wind power plays a significant part in the power production in some countries. However, fundamental differences exist between conventional thermal, hydro, and nuclear generation and wind power, such as different generation systems and the difficulty in controlling the primary movement of a wind turbine, due to the wind and its random fluctuations. These differences are reflected in the specific interaction of wind turbines with the power system. This book addresses a wide variety of issues regarding the integration of wind farms in power systems. The book contains 14 chapters divided into three parts. The first part outlines aspects related to the impact of the wind power generation on the electric system. In the second part, alternatives to mitigate problems of the wind farm integration are presented. Finally, the third part covers issues of modeling and simulation of wind power system

Modelling and Control Design of Pitch-Controlled Variable Speed Wind Turbines

This chapter provides an overall perspective of modern wind power systems, including a discussion of major wind turbine concepts and technologies. More specifically, of the various wind turbine designs, pitch-controlled variable speed wind turbines controlled by means of power electronic converters have been considered. Among them, direct-in-line wind turbines with full-scale power converter and using direct-driven permanent magnet synchronous generators have increasingly drawn more interests to wind turbine manufactures due to its advantages over the other variable-speed wind turbines. Based on this issue, major operating characteristics of these devices are thoroughly analyzed and a three-phase grid-connected wind turbine system, incorporating a maximum power point tracker for dynamic active power generation is presented. Moreover, a simplified state-space averaged mathematical model of the wind turbine system is provided. An efficient power conditioning system of the selected wind turbine design and a new three-level control scheme by using concepts of instantaneous power in the synchronous-rotating d-q reference frame in order to simultaneously and independently control active and reactive power flow in the distribution network level are proposed. Dynamic system simulation studies in the MATLAB/Simulink environment is used in order to demonstrate the effectiveness of the proposed multi-level control approaches in d-q coordinates and the full detailed models presented. The fast response of power electronic devices and the enhanced performance of the proposed control techniques allow taking full advantage of the wind turbine generator.Fil: Molina, Marcelo Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Mercado, Pedro Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentin

Stability of distribution networks connected with distributed generation

Bibliography: pages 164-167.This thesis describes an investigation into the stability of distribution networks that are connected with distributed generators. Due to the restructuring of the electricity industry in the region as well as environmental concerns, distributed generation is bound to increase at a higher rate in the Southern African region in the near future. Southern Africa, like many other developing regions, is dominated by electrically weak distribution networks that have relatively high impedance lines. These networks suffer extreme voltage fluctuations when a transient disturbance occurs on the network. The distributed generators are connected onto distribution networks that were designed to operate without any generation, but were designed to receive power from the transmission networks. Once distributed generators are connected to distribution networks, a number of technical challenges are presented. One of the technical challenges includes investigating the stability of distribution networks connected with distributed generation. It would be beneficial to know what effect the connection of distributed generators onto distribution networks would have on the system stability. This is because if the connection of distributed generators onto distribution networks increases instability on the network, the quality of supply of that network would be degraded, therefore the connection of distributed generators must be limited or methods of improving the stability must be implemented. It is important to establish the measures that can be taken to make sure that the generators react in a stable manner when subjected to disturbances and to make sure that the local system stability is not compromised. The first objective of this thesis was to identify the types of generators that are likely to be connected to Southern African distribution networks and investigate their stability. The next objective was to design model distribution networks that would be utilised to highlight key stability issues that are raised when distributed generation is connected to distribution networks. The third objective was to conduct and analyse stability studies on model as well as existing Southern African distribution networks connected with distributed generation, including the assessment of the implications of potential instability such as on the quality of supply. The last objective was to identify various ways of improving the stability of distribution networks that are connected with distributed generation

Modelling of Wind Energy Converters for Slow and Fast Transients

RÉSUMÉ Pour améliorer la précision des études de l'impact de la génération éolienne sur les réseaux électriques, il est nécessaire développer des outils de simulation plus rapides et précis et utiliser des modèles de plus en plus sophistiqués. Les simulations sont généralement et traditionnellement effectuées de façon indépendante pour les phénomènes transitoires rapides et lents. Pour les transitoires lents, l'approche classique est basée sur l'utilisation de méthodes de solution simplifiées avec des approximations. Ces méthodes se classent dans la catégorie des transitoires électromécaniques. Les modèles plus sophistiqués sont basés sur la simulation détaillée de tous les composants d'une éolienne. Ces modèles appartiennent à la catégorie des transitoires électromagnétiques (EMT pour Electromagnetic Transients). Il est cependant très compliqué d'effectuer des simulations détaillées pour des périodes de simulation longues à cause des restrictions de temps de calcul. Cela est particulièrement vrai dans les grandes simulations d'intégration des éoliennes au réseau électrique. L'objectif et l'innovation de cette thèse est la simulation d'éoliennes avec une méthode de type EMT et un logiciel de type EMTP (Electromagnetic Transients Program) en appliquant des techniques de modélisation rapides et la combinaison avec des modèles détaillés. Ainsi les phénomènes lents et rapides peuvent être simulés dans un seul environnement de type EMTP. Un second objectif est la contribution de plusieurs modèles d'éoliennes pour les phénomènes rapides et lents. Cette thèse présente trois types de modèles, deux modèles à valeur moyenne et un modèle détaillé, dans le même environnement du logiciel EMTP-RV et en utilisant les mêmes méthodes numériques. Le développement des modèles de type détaillé sert principalement de référence pour la validation et la démonstration de précision pour les modèles à valeur moyenne.----------ABSTRACT To improve the accuracy of wind generator grid impact studies, it is needed to develop faster and sophisticated models using various simulation tools. The simulations are usually carried out independently for fast and slow transients. Traditional slow transient analysis methods are based on simplified solution methods with various approximations. These methods fall into the category of electromechanical transients. More sophisticated models are based on the detailed simulation of all wind generator components. Such models fall into the category of electromagnetic transients (EMT). It is, however, complicated to run detailed simulations for long simulation periods due to computer time restrictions. This is especially true in large grid integration simulations. The objective and innovation of this thesis is the simulation of wind generators in EMTP-type (Electromagnetic Transients Program) programs using faster modeling techniques with small integration time-steps and the capability to combine with detailed models. This way fast and slow transients are solved in the same environment and with acceptable computational speed. Another objective of this thesis is the contribution of wind generator models for wind farm integration studies. This thesis presents the integration of three types of models, two mean value type models and one detailed EMTP-type (Electromagnetic Transients Program type), in the same EMTP-RV (software of EMTP-type) environment and with the same numerical methods. The mean value type models are distinguished by their precision levels. At the first level the model is demonstrated to contribute to significant reduction of computing time while limiting the loss of accuracy. At the second level the model provides precision improvement over the first level while still limiting computational efforts. The presented modeling techniques are validated using comparative simulation techniques based on EMTP-RV and PSS/E. PSS/E is only used for the simulation of electromechanical transients