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

OFFSHORE WIND ENERGY STUDY AND ITS IMPACT ON SOUTH CAROLINA TRANSMISSION SYSTEM

As one of the renewable resources, wind energy is developing dramatically in last ten years. Offshore wind energy, with more stable speed and less environmental impact than onshore wind, will be the direction of large scale wind industry. Large scale wind farm penetration affects power system operation, planning and control. Studies concerning type III turbine based wind farm integration problems such as wind intermittency, harmonics, low voltage ride through capability have made great progress. However, there are few investigations concerning switching transient impacts of large scale type III turbine based offshore wind farm in transmission systems. This topic will gain more attention as type III wind generator based offshore wind farm capacity is increasing, and most of these large scale offshore wind farms are injected into transmission system. As expected to take one third of the whole wind energy by 2030, the large offshore wind energy need to be thoroughly studied before its integration particularly the switching transient impacts of offshore wind farms. In this dissertation, steady state impact of large scale offshore wind farms on South Carolina transmission system is studied using PSSE software for the first time. At the same time, the offshore wind farm configuration is designed; SC transmission system thermal and voltage limitation are studied with different amount of wind energy injection. The best recommendation is given for the location of wind power injection buses. Switching transient also impacts is also studied in using actual South Carolina transmission system. The equivalent wind farm model for switching transient is developed in PSCAD software and different level of wind farm penetration evaluates the transient performance of the system. A new mathematical method is developed to determine switching transient impact of offshore wind farm into system with less calculation time. This method is based on the frequency domain impedance model. Both machine part and control part are included in this model which makes this representation unique. The new method is compared with a well-established PSCAD method for steady state and transient responses. With this method, the DFIG impact on system transients can be studied without using time-domain simulations, which gives a better understanding of the transient behaviors and parameters involved in them. Additionally, for large scale offshore wind energy, a critical problem is how to transmit large offshore wind energy from the ocean efficiently and ecumenically. The evaluation of different offshore wind farm transmission system such as HVAC and HVDC is investigated in the last chapter

Supervisory Control of Full Converter Wind Generation Systems to Meet International Grid Codes

This thesis proposes a new supervisory control scheme for full converter wind generators (FCWGs) in compliance with the latest international grid codes. Intermittent behaviour of wind turbines and maximum converter capacity are taken into account in determining the reactive power injection to the grid following severe disturbance. Detailed simulations show that the proposed controller can improve the fault-ride-through capability of FCWGs while also providing support to the network as required by the grid codes

Intentional Controlled Islanding in Wide Area Power Systems with Large Scale Renewable Power Generation to Prevent Blackout

Intentional controlled islanding is a solution to prevent blackouts following a large disturbance. This study focuses on determining island boundaries while maintaining the stability of formed islands and minimising load shedding. A new generator coherency identification framework based on the dynamic coupling of generators and Support Vector Clustering method is proposed to address this challenge. A Mixed Integer Linear Programming model is formulated to minimize power flow disruption and load shedding, and ensure the stability of islanding. The proposed algorithm was validated in 39-bus and 118-bus test systems

Energetic macroscopic representation control method for a hybrid-source energy system including wind, hydrogen, and fuel cell

This paper proposes a new control method for a hybrid energy system. A wind turbine, a hydrogen energy storage system, and a proton exchange membrane fuel cell are utilized in the system to balance the load and supply. The system is modeled in MATLAB/Simulink and is controlled by an improved energetic macroscopic representation (EMR) method in order to match the load profile with wind power. The simulation and test results have proved that (1) the proposed system is effective to meet the varying load demand with fluctuating wind power inputs, (2) the hybrid energy storage system can improve the stability and fault-ride-through performance of the system, and (3) the dynamic response of the proposed system is satisfactory to operate with wind turbines, energy storage, and fuel cells under EMR control

Grid Strength Assessment Trough Q-V Modal Analysis and Maximum Loadability of a Wind-Dominated Power System Using P-Q Regions

Climate change is a menace to the existence of the world and policymakers are trying totackle this phenomenon by deploying large-scale wind farms into their grids. Among them, wind energy shows a promising future to substitute the traditional power plants. However, the deployment of these wind farms into the grid is not a panacea that does not pose any challenges to the grid operators. Keeping the power system voltage stable while considering the strength of the transmission grid is among the major challenges facing by the transmission system operators. Amid normal operation and fault conditions, wind farms should help the grid in reactive power supply according to the grid codes to ride through the fault. In doing so, during fault conditions or heavy loading conditions, the voltage of the power system will not deteriorate. A wind farm, most of the time, is incapable to meet the grid codes requirements without reactive power support. For the compensation of the reactive power deficit, FACTS devices are extensively used. The most popular FACTS devices used by electric utilities are, STATCOM, SVC, SSSC, TCSC, and UPFC. In this work, attention is given to the amelioration of transient stability in wind-dominated power systems via STATCOM and SSSC. Furthermore, a systematic approach to locate large wind power plants to an existing transmission grid is developed by combining the QV-modal analysis, Q-V curves, and P-Q method. The steady-state voltage stability at different wind power penetration levels is investigated while considering the weakest and the strongest region of the power system. The P-Q region method is used to size the wind farm in each scenario. The reliability of the system is verified from the worst contingencies with the wind farm connected at the most vulnerable bus of the system in reactive power capability. The system considered for testing is the modified IEEE 14 bus system

Application of double fed induction generator wind systems to weak networks

Application of double fed induction generator (DFIG) wind generators to weak networks hasbeen limited, particularly when these networks have large industrial loads which exhibittransient conditions on a regular basis. This research thesis examines the application ofDFIG wind generators to weak networks and establishes the requirements for suchintegration

Large Grid-Connected Wind Turbines

This book covers the technological progress and developments of a large-scale wind energy conversion system along with its future trends, with each chapter constituting a contribution by a different leader in the wind energy arena. Recent developments in wind energy conversion systems, system optimization, stability augmentation, power smoothing, and many other fascinating topics are included in this book. Chapters are supported through modeling, control, and simulation analysis. This book contains both technical and review articles

Power Converter of Electric Machines, Renewable Energy Systems, and Transportation

Power converters and electric machines represent essential components in all fields of electrical engineering. In fact, we are heading towards a future where energy will be more and more electrical: electrical vehicles, electrical motors, renewables, storage systems are now widespread. The ongoing energy transition poses new challenges for interfacing and integrating different power systems. The constraints of space, weight, reliability, performance, and autonomy for the electric system have increased the attention of scientific research in order to find more and more appropriate technological solutions. In this context, power converters and electric machines assume a key role in enabling higher performance of electrical power conversion. Consequently, the design and control of power converters and electric machines shall be developed accordingly to the requirements of the specific application, thus leading to more specialized solutions, with the aim of enhancing the reliability, fault tolerance, and flexibility of the next generation power systems