Grid Integration Of Wind Farms Research Articles

Detailed Nonlinear Modeling and High-Fidelity Parallel Simulation of MMC With Embedded Energy Storage for Wind Farm Grid Integration

Detailed Nonlinear Modeling and High-Fidelity Parallel Simulation of MMC With Embedded Energy Storage for Wind Farm Grid Integration

Grid integration of wind farms and the interconnection requirements for the U.S. grid

Abstract The integration of wind turbines and wind farms into the power grid presents significant challenges, including the variable and uncertain nature of wind power, the need for efficient transmission and distribution of power, and the need for advanced control and monitoring systems. Recent advances in wind turbine and wind farm technology have greatly improved their ability to integrate into the power grid. This includes the use of variable speed generators and power electronics, such as inverters, which allow for more accurate control of the power output and better alignment with the grid’s frequency. Additionally, advanced control algorithms, such as model predictive control and feedback linearization, have been developed to improve the stability and reliability of wind power systems. Communication systems have also been integrated into wind power systems to allow for real-time monitoring and control of the wind farm’s performance. This improves the ability of the wind farm to provide ancillary services, such as frequency regulation and voltage control. In this work, the major interconnection requirements for the U.S. grid for the expected mass integration of wind farms were discussed focusing on sustainable and reliable control strategies. The paper explores various control schemes that are used for providing response for grid reliability and sustainability. The analysis also included the future steps that OEMs of wind turbines need to take and the regulatory framework that is needed for ancillary services to provide an equitable platform for all generating units – conventional and renewables.

Synchrophasor Data Based Q-V Droop Control of Wind Farm Integrated Power Systems

With increasing scalability of grid-integrated wind farms (WFs), reactive power ancillary service through Q-V droop control of doubly-fed inducton generators (DFIGs) is one of the prime interests of power system operators. However, variable and uncertain availability of wind-resource at the wind turbines creates challenge against allocating reactive power reserve at the WFs for maintaining voltage stability of the grid. This issue can be resolved through online coordination among the WFs. This paper proposes a synchrophasor data based Q-V droop (SQVD) control technique for the WFs integrated to the grid through different point of common couplings (PCCs) in the power system transmission network. The data from the phasor measurement units (PMUs) at the WF-connected PCCs are used to obtain synchronized Q-V droop gain for each WF. Further, distributed coordination among DFIGs within each WF is performed to allocate optimum reactive power share at the converters. The total reserve of each WF is employed by their synchronized droop, in improving voltage stability at both the local PCC and neighboring PCCs. Performance of SQVD is verified at 418-bus practical Indian power system, in different dynamic situations of the grid, and found to be more effective as compared to the constant Q-V droop and variable Q-V droop control methods.

An active primary frequency regulation strategy for grid integrated wind farms based on model predictive control

The increasing penetration level of wind power can reduce the dependency on fossil fuels, but it is accompanied with challenges such as the jeopardized dynamic stability of the frequency of power grid. As an effective method to improve frequency dynamic stability, primary frequency regulation (PFR) is conventionally based on the feedback of measured frequency, by which means it is conducted through analyzing historical information. By taking the predictive information into account, this paper introduces an active PFR (APFR) strategy for grid integrated wind farms (WFs) to enhance control performance of PFR. According to small-signal models of power system integrated with WFs based on conventional PFR and APFR, the state-space predictive models are established to obtain the predictive states. Then, to take active measures to deal with the electrical load disturbance, the predicted frequency is optimized in a receding horizon period by adjusting the PFR power reference of WFs flexibly. Moreover, a finite terminal weighting matrix based lyapunov function is presented to prove the asymptotic stability of the closed-loop model predictive control system. Finally, extensive case studies based on the standard test systems are performed to validate the effectiveness of the theoretical analysis and the superiority of APFR strategy.

Dynamic Control of Integrated Wind Farm Battery Energy Storage Systems for Grid Connection

The intermittent nature of wind power is a major challenge for wind as an energy source. Wind power generation is therefore difficult to plan, manage, sustain, and track during the year due to different weather conditions. The uncertainty of energy loads and power generation from wind energy sources heavily affects the system stability. The battery energy storage system (BESS) plays a fundamental role in controlling and improving the efficiency of renewable energy sources. Stochasticity of wind speed and reliability of the main system components are considered. This paper presents a dynamical control system based on model predictive control (MPC) in real time, to make full use of the flexibility and controllability of energy storage to mitigate problems of wind farm variability and intermittency. The control scheme first plans the expected output, then stochastic optimization is used to optimize grid integrated wind farm BESS output power, develop an optimal operation strategy for BESS, and prevent some unpredictable conditions that may have impacts on the stability of the system. The results show that the proposed method can reduce grid-connected wind power fluctuations, limit system faults, control command for the BESS in the dispatching period, and ensure system stability for grid connection.

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.

Wind-Turbine and Wind-Farm Flows: A Review

Wind energy, together with other renewable energy sources, are expected to grow substantially in the coming decades and play a key role in mitigating climate change and achieving energy sustainability. One of the main challenges in optimizing the design, operation, control, and grid integration of wind farms is the prediction of their performance, owing to the complex multiscale two-way interactions between wind farms and the turbulent atmospheric boundary layer (ABL). From a fluid mechanical perspective, these interactions are complicated by the high Reynolds number of the ABL flow, its inherent unsteadiness due to the diurnal cycle and synoptic-forcing variability, the ubiquitous nature of thermal effects, and the heterogeneity of the terrain. Particularly important is the effect of ABL turbulence on wind-turbine wake flows and their superposition, as they are responsible for considerable turbine power losses and fatigue loads in wind farms. These flow interactions affect, in turn, the structure of the ABL and the turbulent fluxes of momentum and scalars. This review summarizes recent experimental, computational, and theoretical research efforts that have contributed to improving our understanding and ability to predict the interactions of ABL flow with wind turbines and wind farms.

Wind power fluctuation compensation by variable speed pumped storage plant in a grid integrated system: Frequency spectrum analysis

An electrical power generation from the wind technology is the most rapidly growing technology due to its ample characteristics. Nevertheless, because of its stochastic feature, it has unnecessary impacts on the operation s and stability of the power grid system. The fluctuation of the grid frequency problem, for example, is more pronounced. The fluctuation of the frequency in turn impacts even the collapse of the power system. To minimize such problem, a droop-vector control strategy applied on a doubly-fed induction machine based (DFIM) variable speed pumped storage (VSPS) system is proposed in this paper. This method is supposed to be used as a wind power fluctuation compensation solution in the wind farm-grid integration system. The system model is made on the basis of the technique called a phasor model. The frequency spectrum analysis approach is used in the VSPS plant for determining the dynamic performances of the grid in case of contingencies including wind power fluctuation compensation. The software platform MATLAB/Simulink is used for verifying the performance of the proposed system. The results show that the method of frequency spectrum analysis technique is effective for determining the wind power fluctuation and stability requirement in the large power network. The control strategy proposed on this paper implementing the VSC-DFIM based VSPS plant integrated with the power gird and wind farm network achieves well-controlled power flow and stable grid frequency with the deviations in acceptable ranges.

PMSG‐based wind energy conversion systems: survey on power converters and controls

The permanent magnet synchronous generator (PMSG) is dominantly used in the present wind energy market. Reflecting the latest wind energy market trends and research articles, this study presents a survey on important electrical engineering aspects for PMSG-based megawatt-level wind energy conversion systems (WECSs). A comprehensive analysis on power converter topologies for wind turbines (WTs), grid integration of wind farms, digital control schemes, fault-ride-through compliance methods, and future trends is presented. The updated market share, technology trends, WT products information, in-depth technical analysis, and promising research works highlighted in this study will help the reader to understand the state-of-the-art and emerging technologies for PMSG-based WECS.

Voltage Stability Enhancement of Fixed Speed Wind Energy Conversion System

Fixed speed wind energy conversion systems based on squirrel cage induction generator (SCIG) has a significant existence in wind energy technology. Availability of reactive power is obligatory for the reliable and stable performance of the power system. Insufficient reactive power has navigated to voltage collapses and has been a foremost source of various recent major power outages universally. This paper exhibits the simulation results of a grid integrated wind farm with and without reactive power compensation by capacitor banks and static synchronous compensator (STATCOM) to achieve voltage stability improvement during startup, normal operation, symmetrical and unsymmetrical fault conditions. The effect of reactive power compensation on voltage profile is compared.

Dynamic equivalent of wind farm model for power system stability studies

ABSTRACTA new dynamic equivalencing method for stability assessment of a grid-integrated wind farm is proposed in this article. The accuracy of the method is validated for a 34-bus system with 28-unit wind farm connected to Indian utility system. This wind farm consists of several wind turbines of two different ratings. The electrical parameters of the equivalent generator are derived from the mathematical model of the squirrel-cage induction generator. The parameters of the equivalent wind-turbine generator are optimized to yield minimum deviation from the detailed system response using genetic algorithm. The small-signal and transient stability responses of the study system with detail wind farm and equivalent model are simulated using MATLAB. Equivalent model eigenvalues are compared to the centre of inertia based detailed system eigenvalue. In addition, the computed eigenvalues and time-domain responses of the proposed equivalent model, detailed wind farm are compared against weighted model proposed earlier. In most of the investigated cases, the average error of dynamic responses between the proposed equivalent and detailed models are less when compared to weighted model. Thus, the large-signal responses of the proposed equivalent model show superior agreement with detailed system response.

A Compact DC-DC Converter for Offshore Wind Farm Application

A DC-DC converter suitable for the grid integration of windfarms through a DC grid is presented. The operation is based on the Marx principle where charged capacitors are connected in series and parallel in turn to achieve the voltage transformation. The two inductors at the two ends of the converter are designed to resonate with the capacitors to create resonance forcing current zeros to enable zero current switching thereby reducing switching losses. The design of a 50 MW, 6kV/30kV DC-DC converter was carried out by analysis and simulation

Negative sequence current controlled grid integrated wind farm connected to ANFIS based HVDC light transmission system

This paper investigates the fast AC fault recovery capability, fast and independent control of active/reactive power of the grid integrated wind farm based HVDC light transmission system. These capabilities are most desired in future grids with high penetration of renewable energy sources like wind and solar. Here, a negative sequence current controller is implemented for the wind turbine generator to mitigate the power oscillations and dc link voltage excursions within the HVDC light system during fault conditions. On the other hand, converters are controlled through adaptive neuro fuzzy inference system (ANFIS) based controller. The test system consists of synchronous generator, a doubly fed induction generator (DFIG) based wind farm and a voltage source converter based HVDC light transmission system, modeled in Matlab/Simpower Systems software. The design is fully tested on a digital simulator to demonstrate the effectiveness of the model in terms of fault recovery under various operating conditions.

Key technologies of VSC-HVDC and its application on offshore wind farm in China

In recent years, wind power industry has been flourishing and in China the focus has been gradually shifted from land-based to offshore wind farms. There are many advantages for offshore wind farms, such as abundant wind energy reserves, high utilization of the wind turbine capacity, not taking up land resources and so on. As wind turbine technology improves, offshore wind farms have been expanding quickly and are located further away from the onshore grid. The power transmission problem has become one of the key issues for restricting the development of offshore wind farms. For example, the technology of high voltage direct current transmission based on voltage source converter (VSC-HVDC), suitable for long-distance transmission of offshore wind energy, has become one of the current research focuses. This has resulted in higher requirements on the aspects of converter voltage level, system dynamic performance, and network power quality. The paper first discusses converter topology for offshore wind farm grid integration. Two VSC-HVDC projects for connecting offshore wind farms, which are located in Shanghai and Dalian of China, are presented in detail. Based on the two projects, the structure, control methods and application of modular multi-level converter are presented. The control strategies of VSC-HVDC are then discussed, focusing on double closed-loop vector control, direct power control, deadbeat control and the control methods for unbalanced grid voltage. This can provide good theoretical foundation for the grid integration of large offshore wind farms.

Wind Farm Grid Integration Simulation Analysis of the Impact of Power System Transient Stability

Analysis compares the direct access to a single set of wind power systemTwo groups of wind farm access system directlyMultiple sets of wind farm access system directly And Multiple sets of wind dispersion access system's impact on power system transient stability. And compare the simulation results, Concluded that wind farm access capacity and its topology structure's influence on system transient stability.

Study on the Active Power Output Control of Wind Energy for Power Balance

This paper carried out a study on the contribution of wind farm to power balance of power system by wind power output control. The study mainly focuses on active power control capability of double feed induction generator (DFIG) based wind turbine, active power control mode of wind farm and capability of wind farm to participating in peak-load regulation. According to the National standard of China GB/T 19963-2011, a study case is given to simulate the impact of wind farm grid integration based on a real power system in order to validate the active power mode and control process presented in the paper.

Offshore Wind Farm Grid Integration by VSC Technology With LCC-Based HVDC Transmission

High-voltage dc (HVDC) transmission based on the line-commutated converter (LCC) is the most established and widespread technology around the world. However, HVDC based on the voltage source converter (VSC) has emerged as the best option to integrate renewable energy sources, e.g., offshore wind farms. This work investigates the feasibility of using a conventional LCC-HVDC transmission in combination with a VSC to integrate offshore wind farms. Such integration results in a hybrid HVDC connection, i.e., the connection of a VSC with an LCC through a dc cable. The operational features of a model of three-terminal hybrid HVDC, two LCC stations and one VSC station, is investigated using PSCAD/EMTDC. The simulations include an aggregate model to emulate the wind farm. The corresponding control strategies are proposed for each terminal and verified under various conditions including wind speed variations and ac faults.

Power quality assessment of wind turbines and comparison with conventional legal regulations: A case study in Turkey

Renewable energy sources have been investigated for use instead of conventional fossil fuels in many areas. Among these renewable energy sources, wind energy has come into prominence owing to the fact that it is a clean, sustainable and cost-effective type of energy. However, the connection of large wind farms to the grid may cause problems in terms of power quality due to the variability of the energy extracted from the wind. The mentioned power quality problems are generally taken into consideration after the grid integration of wind farms. However, the precautions that can be taken by means of the assessments before the installation of the turbines represent an easier and more economic way. In this study, the possible effects of the grid connected wind turbines on the power quality characteristics have been defined and the MATLAB based models have been constructed so as to calculate these effects. Particularly, fast voltage variations that are difficult to model due to their relations with the human factor have been analyzed in detail. It has been aimed that the models are suitable for use in practice while utilizing various standards such as IEC 61400-21 and IEC 61000-4-15 in order to setup the models. The analyses of the implementations that represent constraints for exploiting the wind resources in Turkey have been realized in terms of production and consumption with a case study. The realized calculations present the applicability of the model to grid conditions with different characteristics. It is also presented that the wind energy penetration can be increased without deteriorating the power quality of the grid with the use of the proposed model.

Solutions for the grid integration of wind farms—a survey

AbstractThis article presents a survey of different possible technical solutions for the grid integration of wind farms. These solutions concern the main problems encountered today and, whenever possible, examples of actual implementation in wind farm projects are given. More specifically the following types of solutions are discussed: choice of an appropriate wind turbine generator technology; solutions based on co‐ordinated wind farms and power system operation; reactive compensation and voltage control systems; fault ride‐through systems; energy storage systems; current limitation devices; directional protections; etc. Copyright © 2005 John Wiley & Sons, Ltd.

Grid Integration of Wind Farms

AbstractThis article gives an overview of grid integration of wind farms with respect to impact on voltage quality and power system stability. The recommended procedure for assessing the impact of wind turbines on voltage quality in distribution grids is presented. The procedure uses the power quality characteristic data of wind turbines to determine the impact on slow voltage variations, flicker, voltage dips and harmonics. The detailed assessment allows for substantially more wind power in distribution grids compared with previously used rule‐of‐thumb guidelines. Power system stability is a concern in conjunction with large wind farms or very weak grids. Assessment requires the use of power system simulation tools, and wind farm models for inclusion in such tools are presently being developed. A fixed‐speed wind turbine model is described. The model may be considered a good starting point for development of more advanced models, hereunder the concept of variable‐speed wind turbines with a doubly fed induction generator is briefly explained. The use of dynamic wind farm models as part of power system simulation tools allows for detailed studies and development of innovative grid integration techniques. It is demonstrated that the use of reactive compensation may relax the short‐term voltage stability limit and allow integration of significantly more wind power, and that application of automatic generation control technology may be an efficient means to circumvent thermal transmission capacity constraints. The continuous development of analysis tools and technology for cost‐effective and secure grid integration is an important aid to ensure the increasing use of wind energy. A key factor for success, however, is the communication of results and gained experience, and in this regard it is hoped that this article may contribute. Copyright © 2003 John Wiley & Sons, Ltd.