Application of Unified Power Flow Controller to Improve the Performance of Wind Energy Conversion System

This research introduces the unified power flow controller (UPFC) as a means to improve the overall performance of wind energy conversion system (WECS) through the development of an appropriate control algorithm. Also, application of the proposed UPFC control algorithm has been extended in this research to overcome some problems associated with the internal faults associated with WECS- voltage source converter (VSC), such as miss-fire, fire-through and dc-link faults

A New Converter Station Topology to Improve the Overall Performance of a Doubly Fed Induction Generator-Based Wind Energy Conversion System

This thesis presents a reliable and cost effective technique that calls for reconfiguration of the existing converters of a typical Doubly Fed Induction Generator to include a coil of low internal resistance. A coil within the DC link is the only hardware component required to implement this technique. With a proper control scheme, activated during fault conditions, this coil can provide the same degree of performance as a superconducting magnetic energy storage unit during fault conditions

Performance Enhancement of Wind Farms Using Tuned SSSC Based on Artificial Neural Network

Recently, power systems are confronting a lot of challenges. Increasing the dependence on renewable energy sources especially wind energy and its impact on the stability of electrical systems are the most important challenges. Flexible alternating current transmission systems (FACTS) can be used to improve the relationship between wind farms and electrical grids. The performance of these FACTS depends on the parameters of its control system. These parameters can be tuned using modern methods like Artificial Neural Network (ANN). In this paper, ANN is used to improve the performance of static synchronous series compensator (SSSC) integrated into combined wind farm (CWF). This CWF is composed of squirrel cage induction generators (SCIG) and doubly fed induction generators (DFIG) wind turbines. This wind farm is collecting the advantage of SCIG and DFIG wind turbines. To view out the motivation of this paper, a comparison is done among the performances of combined wind farm (CWF) with ANN-SSSC, CWF with ordinary SSSC and CWF with SSSC tune by Multi-objective genetic algorithm (MOGA SSSC). The root mean square Error (RMSE) is used to evaluate the results. The results illustrate that the performance of CWF can be improved using SSSC adjusted by ANN

Offshore Wind Farm-Grid Integration: A Review on Infrastructure, Challenges, and Grid Solutions

Recently, the penetration of renewable energy sources (RESs) into electrical power systems is witnessing a large attention due to their inexhaustibility, environmental benefits, storage capabilities, lower maintenance and stronger economy, etc. Among these RESs, offshore wind power plants (OWPP) are ones of the most widespread power plants that have emerged with regard to being competitive with other energy technologies. However, the application of power electronic converters (PECs), offshore transmission lines and large substation transformers result in considerable power quality (PQ) issues in grid connected OWPP. Moreover, due to the installation of filters for each OWPP, some other challenges such as voltage and frequency stability arise. In this regard, various customs power devices along with integration control methodologies have been implemented to deal with stated issues. Furthermore, for a smooth and reliable operation of the system, each country established various grid codes. Although various mitigation schemes and related standards for OWPP are documented separately, a comprehensive review covering these aspects has not yet addressed in the literature. The objective of this study is to compare and relate prior as well as latest developments on PQ and stability challenges and their solutions. Low voltage ride through (LVRT) schemes and associated grid codes prevalent for the interconnection of OWPP based power grid have been deliberated. In addition, various PQ issues and mitigation options such as FACTS based filters, DFIG based adaptive and conventional control algorithms, ESS based methods and LVRT requirements have been summarized and compared. Finally, recommendations and future trends for PQ improvement are highlighted at the end

Enhancement of Transient Stability of DFIG Based Variable Speed Wind Generator Using Diode-bridge-type Non-superconducting Fault Current Limiter and Resistive Solid State Fault Current Limiter

The application of doubly-fed induction generator (DFIG) is very effective in the fast-growing wind generator (WG) market. The foremost concern for the DFIG based WG system is to maintain the transient stability during fault, as the stator of the DFIG is directly connected to the grid. Therefore, transient stability enhancement of the DFIG is very important. In this work, a diode-bridge-type nonsuperconducting fault current limiter (NSFCL) and resistive solid-state fault current limiter (R-type SSFCL) are examined to augment the transient stability of the DFIG based WG system.In simulations, temporary balanced and unbalanced faults were applied in the test system to investigate the proposed NSFCL and the R-type SSFCL transient stability performance. Besides a DC resistive superconducting fault current limiter (SFCL), bridge-type fault current limiter (BFCL) and series dynamic braking resistor (SDBR) are also considered to compare their performance with the proposed NSFCL and R-type SSFCL. These simulations were performed with Matlab/Simulink software. Simulation results clearly indicate that the NSFCL and R-type SSFCL enhances the transient stability of the DFIG based WG. Moreover, the NSFCL works better than the DC resistive SFCL, BFCL and SDBR in every aspect and R-type SSFCL works better than the SDBR in all aspect

Stability aspects of wind power integration in power systems and microgrids

Wind farms can be located in remote and weak parts of power networks, due to the availability of wind energy. With integration of power from such wind farms, the power system’s stability might be affected especially at higher penetration levels. Instability issues resulting from such incorporations must be addressed to accommodate higher wind power penetration in the power networks. This thesis attempts to analyse the stability issues of power system with integration of variable speed wind turbine technology especially focusing on doubly fed induction generators. Additionally, a microgrid with different inertial and non-inertial sources is examined for enhancing design aspect of such microgrids from stability perspectives. At different penetration levels of wind power, oscillatory modes are identified, and participation factors of the most associated state variables on such oscillatory modes are observed. Flexible ac transmission system based series and shunt devices are found effective in enhancing the small signal stability of such power networks for different wind power penetration levels. Besides, series devices are observed to contribute to an improvement in the transient behaviour of the power system. Similarly, high voltage dc link is also witnessed to positively influence low frequency oscillation damping. Furthermore, this thesis shows that higher voltage gain values of wind farms can contribute to an improvement in the small signal stability for increased wind power penetration. Another observation displays that a doubly fed induction based wind farm can contribute to improving the voltage stability of a distribution network in a steady state operating condition, as well as following disturbances. Based on the study on an isolated microgrid that has a combination of synchronous, converter-based distributed resources, and energy storage systems, it is observed that a suitable modification in such microgrid’s various components and parameters can positively influence its small signal stability

Fault Ride-Through Capacity Enhancement of Fixed Speed Wind Generator by A Modified Bridge-type Fault Current Limiter

Fault Ride-Through (FRT) is a common requirement to abide by grid code all over the world. In this work, to enhance the fault ride-through capability of a fixed speed wind generator system, a modified configuration of Bridge-Type Fault Current Limiter (BFCL) is proposed. To check the effectiveness of the proposed BFCL, its performance is compared with that of the Series Dynamic Braking Resistor (SDBR). A harmonic performance improvement by the proposed method is also analyzed. Three-line-to-ground (3LG), line-to-line (LL) and single-line-to-ground (1LG) faults were applied to one of the double circuit transmission lines connected to the wind generator system. Simulations were carried out using Matlab/Simulink software. Simulation results show that the proposed BFCL is very effective device to achieve the FRT and suppress fault current that eliminates the need for circuit breaker replacement. Also, the BFCL improves the harmonic performance and helps follow harmonic grid code. Moreover, it was found that the BFCL works better than the SDBR, and has some distinct advantages over the SDBR