Penetration Level Of Wind Energy Research Articles

Distribution system with wind penetration

This article presents the results of the analysis of the studies of the operation of a modified IEEE-13 distribution feeder, which was built to scale in the laboratory at Universidad del Norte. In this article, we show the cases of the operating regimes of the modified IEEE-13, before the different levels of wind energy penetration. The modified IEEE-13 distribution feeder was built taking into account that each of the scaled modules and their generator-load will work under the conditions of the Universidad del Norte laboratory. An experimental methodology was used to compare the results obtained in the actual scaled model with the results of the simulations in specialized programs. The conclusions of the article show the wind energy that can be injected into an electrical system with conventional power generation so that it can maintain its operation complying with the current regulatory framework.
 
 

Wind energy, the price of carbon allowances, and CO2 emissions: Evidence from Ireland

Increased reliance on renewable energy is an important component of the European Union's action plan for reducing carbon emissions. Another key instrument is the European Union Emission Trading System (EU ETS), which caps the overall level of emissions and then permits trade among the emitters.Using data from Ireland, this paper examines the effects of wind energy and the EU ETS on carbon emissions from electricity generation. We estimate a time-series econometric model of CO2 emissions for each half hour over the period 1 January 2015 through 17 April 2018. Results indicate that increases in the carbon allowance price significantly reduce carbon emissions when errors in load assessments and wind energy forecasts are equal to zero. Specifically, emissions over the out-of-sample evaluation period would have been 6% higher in the absence of the EU ETS. Moreover, findings suggest that higher wind energy penetration levels substantially reduce emissions. In particular, out-of-sample analysis suggests that emissions would have been 14.6 percent higher in the absence of wind energy.

A novel approach for coordinated operation of variable speed wind energy conversion in smart grid applications

In smart grid applications, the high penetration level of wind energy requires precise coordination of wind energy conversion systems (WECS) with the existing grid. In this paper, a variable speed WECS using Squirrel-Cage Induction Generator (SCIG) is modeled and analyzed under fault conditions. The converters and their controllers are so designed that the complete system works in coordination and the turbine remains operative even under fault conditions. A droop controller regulates the torque and generator speed to limit power generation during faults, thereby preventing a shutdown of the wind turbine. A dual current controller is designed for individual control of positive and negative sequence currents to eliminate the double frequency oscillations that arise at the DC-link voltage during unsymmetrical faults. With the proposed controller, rise in DC link voltage and generator speed is limited to a bounded value of 1.2 pu whereas the fault current is limited to 1.5 pu.

Comprehensive Overview of Low Voltage Ride Through Methods of Grid Integrated Wind Generator

The wind power generation is a rapidly growing grid integrated renewable energy (RE) technology with an installed capacity of 539.291 GW. The capability of the wind energy conversion system (WECS) to remain integrated into the utility network in the case of low voltage events is called low-voltage ride-through (LVRT) capability. This paper offers a comprehensive overview of improvement techniques of the LVRT capability in WECS to increase the wind energy penetration level in the utility grid. Exhibited portrait manifests a broad spectrum of 1) wind turbines, 2) electrical generators used for wind power applications, 3) international grid codes applicable for grid integration of WECS, 4) LVRT fundamentals in WECS, 5) wind turbines LVRT methods by doubly fed induction generator (DFIG), 6) wind turbines LVRT methods by permanent magnet synchronous generators (PMSG), and 7) LVRT methods of wind turbines using squirrel cage induction generator (SCIG). This ready-reckoner paper critically reviews and classifies more than 190 research papers on LVRT issues, practices, and available technologies for grid integration in wind energy systems, and it aims to be a quick reference for the researchers, designers, manufacturers, and engineers working in the same field.

Effects of penetration level and location of wind turbines on shadow prices and congestion of transmission lines

This paper studies the effects of wind power on electricity market parameters. The penetration level of wind energy, location of wind turbines, and integration of multiple wind turbines are the main topics addressed in this paper. Flow-gate marginal pricing is the main electricity market concept which is analyzed and studied. Stochastic programming including wind power uncertainty is presented to minimize the annual operational cost of generators. The Flow-gate marginal pricing of transmission lines is also calculated. The Flow-gate marginal pricing is scrutinized under various wind power sizing, siting, and settings. The location, number, and capacity of wind turbines are changed to find out their impacts on the network Flow-gate marginal pricing. The proposed analyses and simulations are carried out using general algebraic modeling system software.

Hierarchical control scheme for coordinated reactive power regulation in clustered wind farms

Coordinated reactive power regulation is always a critical issue when it comes to a system with a high penetration level of wind energy. This study provides a distributed control scheme for wind farm reactive power regulation, aiming to coordinate the reactive power reference among wind farm clusters. Within the limited communication among neighbouring clusters, fair reactive power generation sharing is achieved. Moreover, the reactive power capability of the wind turbine (WT) is utilised to cooperate with reactive power compensation devices. The characteristics of the collector system are analysed to improve the voltage profile. Instead of averagely assigning the generation order to each WT, the reference is assigned based on voltage sensitivity. Case studies are carried out to validate the performance of the proposed control scheme.

Optimal Sizing of Energy Storage Devices in Isolated Wind-Diesel Systems Considering Load Growth Uncertainty

The development of wind power plants is an economical solution to provide energy to remote communities. For these isolated systems, the cogeneration of diesel generators and wind turbines is a typical configuration, but also poses several technical challenges regarding load balancing and frequency control. Auxiliary devices such as battery storages, flywheels, and dump loads are often needed to ensure a more stable operation and a higher penetration level of wind energy. However, the cost of these auxiliary devices can be substantial. This paper proposes a two-stage stochastic optimization framework to determine the optimal size of energy storage devices in a hybrid wind-diesel system. The optimization problem considers two main uncertain factors, namely the wind speed and the load growth rate. An efficient scenario reduction method is also proposed to reduce the computational burden. The optimization framework is tested with a realistic case study.

Impacts of Wind Power Uncertainty on Grid Vulnerability to Cascading Overload Failures

Higher penetration of renewables like wind power generation will introduce an unprecedented amount of uncertainty into the grid that might severely affect the grid vulnerability to cascading failures. In this study, we propose a mixed OPF-stochastic approach to analyze and simulate cascading failures in power grid and to evaluate the impact of wind generation in terms of its penetration and uncertainty level. The proposed approach incorporates both thermal stability model for transmission line outage and automatic power balance algorithms. Numerical simulation results on the IEEE 300 bus system indicate that uncertainty coming from wind energy has severe impacts on grid vulnerability to cascading overload failures under different contingency scenarios. Results also suggest that higher penetration levels of wind energy, if not managed appropriately, will add to this severity because higher uncertainties may be injected into weaker lines in a grid.

Fast-Frequency Response Provided by DFIG-Wind Turbines and its Impact on the Grid

This paper presents a methodology for the analysis of frequency dynamics in large-scale power systems with high level of wind energy penetration by means of a simplified model for DFIG-based wind turbines. In addition, a virtual inertia controller version of the optimized power point tracking (OPPT) method is implemented for this kind of wind turbines, where the maximum power point tracking curve is shifted to drive variations in the active power injection as a function of both the grid frequency deviation and its time derivative. The proposed methodology integrates the model in a primary frequency control scheme to analyze the interaction with the rest of the plants in the power system. It is also proven that, under real wind conditions, the proposed version of the OPPT method allows us to smooth the wind power injected into the grid, thereby reducing frequency fluctuations.

Statistical analysis of wind energy characteristics in Santiago island, Cape Verde

As a volcanic archipelago, the Republic of Cape Verde relies dominantly on diesel to power its electricity supply. Recognizing the financial and environmental burden of diesel generation and risk of energy security, the government of Cape Verde has launched an ambitious goal of 50% electricity from renewables by 2020, since the country is endowed with high potential of renewable energy resources such as wind and solar. Although the annual average penetration rate of wind power has reached 24% of total electricity production generated in Cape Verde, raising the wind energy penetration level in future will pose numerous challenges for the operation and control of the power system because of wind's inherent intermittency and unpredictability. In this study, a statistical analysis of the wind characteristics in Santiago island, is presented by using historical wind speed and power data of the Santiago wind farm in 2014. A two-parameter Weibull distribution is first applied to model the wind speeds on various timescales and to determine wind energy potential in Santiago island, Cape Verde. The annual average wind speed was 8.57 m/s with a standard deviation close to 3.29 m/s. The monthly Weibull scale parameters varied from 5.64 m/s to 13.7 m/s, while the monthly Weibull shape parameters varied from 1.97 to 9.13. Although the monthly mean power density of the rainy season from August to September was low, the annual mean power density shows that Santiago has good wind potential. Then, an approach to modeling the equivalent power curve based on available wind speed and power output data from the wind farm is proposed. By utilizing the estimated power curve, the uncertainty set of wind power generation, resulted from the uncertainty of wind speed forecast, can be obtained to quantify the power system reserve requirements. A statistical analysis of wind power ramp is also given for estimating the power capacity requirement of the energy storage system that can be considered as a reasonable way to mitigate the wind intermittency and minimize curtailment of wind. Results of this study contribute to assess the wind energy potential of Cape Verde for investors, and can be used to quantify the uncertainties of wind power generation for the power system operator.

Active Power Control of Waked Wind Farms

Active power control can be used to balance the total power generated by wind farms with the power consumed on the electricity grid. With the increasing penetration levels of wind energy, there is an increasing need for this ancillary service. In this paper, we show that the tracking of a certain power reference signal provided by the transmission system operator can be significantly improved by using feedback control at the wind farm level. We propose a simple feedback control law that significantly improves the tracking behavior of the total power output of the farm, resulting in higher performance scores. The effectiveness of the proposed feedback controller is demonstrated using high-fidelity computational fluid dynamics simulations of a small wind farm.

A probabilistic determination of required reserve levels in an energy and reserve co-optimized electricity market with variable generation

The determination of the required reserve levels due to the incremental trend of injecting wind energy into the power grid with a high level of wind energy penetration is complicated because of the variability of wind energy. This study proposes a method, based on the logarithmic barrier interior point method for optimal power flow and Monte Carlo analysis, to evaluate the required reserve levels for a grid with variable generation. A Gaussian distribution was used to model the dynamic load demand, while a unique linearized least-square approximation was used to model the wind turbines. In order to demonstrate the capability of the proposed algorithm, the methodology was applied to a modified IEEE 30-bus system with two wind-farms. The simulation results showed that the determined reserve requirement was considerably reduced compared with that obtained with classical approaches. The proposed method also satisfies all the considered constraints and maintains system reliability.

A Flexible Ramping Capacity Model for Generation Scheduling with High Levels of Wind Energy Penetration

The penetration level of renewable generation has increased significantly in recent years, which has led to operational concerns associated with the system ramping capability. Here, we propose the flexible ramping capacity (FRC) model, which considers the practical ramping capability of generation resources as well as the uncertainty in net load. The FRC model also incorporates the demand curve of the ramping capacity, which represents the hourly economic value of the ramping capacity. The model is formulated mathematically using ramp constraints, which are incorporated into unit commitment (UC) and economic dispatch (ED) processes. Simulations are carried out using a 10-unit system to compare the FRC model with conventional methods. We show that the FRC method can improve reliability and reduce expected operating costs. The simulation results also show that, by using the FRC model, system reliability can be satisfied at high wind power generation levels while achieving economic efficiency.

Quantifying the Economic and Grid Reliability Impacts of Improved Wind Power Forecasting

Wind power forecasting is an important tool in power system operations to address variability and uncertainty. Accurately doing so is important to reduce the occurrence and length of curtailment, enhancing market efficiency, and improving the operational reliability of the bulk power system. This research quantifies the value of wind power forecasting improvements in the IEEE 118-bus test system as modified to emulate the generation mixes of Midcontinent, California, and New England independent system operator balancing authority areas. To measure the economic value, a commercially available production cost modeling tool was used to simulate the multitimescale unit commitment (UC) and economic dispatch process for calculating the cost savings and curtailment reductions. To measure the reliability improvements, an in-house tool, Flexible energy scheduling tool for integrating variable generation, was used to calculate the system's area control error and the North American Electric Reliability Corporation Control Performance Standard 2. The approach allowed scientific reproducibility of results and cross validation of the tools. A total of 270 scenarios were evaluated to accommodate the variation of three factors: generation mix, wind penetration level, and wind forecasting improvements. The modified IEEE 118-bus systems utilized 1 year of data at multiple time scales, including the day-ahead UC, 4-h-ahead UC, and real-time dispatch. The value of improved wind power forecasting was found to be strongly tied to the conventional generation mix, existence of energy storage devices, and the penetration level of wind energy. The simulation results demonstrate that wind power forecasting brings clear benefits to power system operations.

Multi-parameter bifurcation analysis of subsynchronous interactions in DFIG-based wind farms

This work analyzes the dynamics involved in subsynchronous interactions between wind farms and series-compensated transmission lines. This adverse phenomenon may arise when doubly-fed induction generators are radially connected to an ac transmission line with series capacitive compensation. The resulting subsynchronous oscillations can produce the system instability and cause a severe damage to the wind turbines. The study is carried out combining tools from bifurcation theory, eigenvalue analysis and nonlinear time-domain simulations. The impact on the subsynchronous mode due to the variation of a set of key parameters is considered. These parameters include the series compensation of the transmission line, the wind speed (generated power), the wind energy penetration level, and a gain of the internal control loop of the wind turbine. The bifurcation study determines that the underlying mechanism associated with the appearance of subsynchronous oscillations can be explained by means of Hopf bifurcations of the equilibrium point and their corresponding limit cycles. In addition, the saturation of the wind turbine converters plays an important role in the dynamics, introducing non-smooth bifurcations that are also analyzed.

Enhanced fault location algorithm for smart grid containing wind farm using wireless communication facilities

Modern smart grid (SG) should efficiently accommodate the renewable resources such as wind energy under different operation conditions. High level of wind energy penetration into SG results in operation constraints to avoid any tripping out of wind generators from the grid during fault conditions. Therefore, following the fault occurrence, the utility has to restore power as quickly as possible. This requires accurate and efficient fault location algorithms to have appropriate action for rapid service restoration. This study presents two fault location algorithms taking into account the dynamic behaviour of wind farm generation. In the first conventional algorithm, fault location is estimated using the recorded voltage and current signals at one end of the line. While second algorithm is two-end fault location based on the synchronised voltage and current signals from the line ends. Calculations are carried out in time domain within half cycle using movable windows for recorded signals. The obtained results of two-end algorithm are superior and more accurate compared with the conventional one-end fault location algorithm. This is attributed to SG facilities with modern communication links and data synchronisation technology. The proposed algorithms are tested through grid and wind farm simulations to justify their effectiveness.

An Optimal Integrated Control Scheme for Permanent Magnet Synchronous Generator-Based Wind Turbines under Asymmetrical Grid Fault Conditions

In recent years, the increasing penetration level of wind energy into power systems has brought new issues and challenges. One of the main concerns is the issue of dynamic response capability during outer disturbance conditions, especially the fault-tolerance capability during asymmetrical faults. In order to improve the fault-tolerance and dynamic response capability under asymmetrical grid fault conditions, an optimal integrated control scheme for the grid-side voltage-source converter (VSC) of direct-driven permanent magnet synchronous generator (PMSG)-based wind turbine systems is proposed in this paper. The optimal control strategy includes a main controller and an additional controller. In the main controller, a double-loop controller based on differential flatness-based theory is designed for grid-side VSC. Two parts are involved in the design process of the flatness-based controller: the reference trajectories generation of flatness output and the implementation of the controller. In the additional control aspect, an auxiliary second harmonic compensation control loop based on an improved calculation method for grid-side instantaneous transmission power is designed by the quasi proportional resonant (Quasi-PR) control principle, which is able to simultaneously restrain the second harmonic components in active power and reactive power injected into the grid without the respective calculation for current control references. Moreover, to reduce the DC-link overvoltage during grid faults, the mathematical model of DC-link voltage is analyzed and a feedforward modified control factor is added to the traditional DC voltage control loop in grid-side VSC. The effectiveness of the optimal control scheme is verified in PSCAD/EMTDC simulation software.

Optimal wind energy penetration in power systems: An approach based on spatial distribution of wind speed

Contributing in power system expansions, the present study establishes an efficient scheme for optimal integration of wind energy resources. The proposed approach highly concerns the spatial distribution of wind speed at different points of a wind farm. In mathematical statements, a suitable probability distribution function (PDF) is well-designed for representing such uncertainties. In such conditions, it is likely to have dissimilar output powers for individual and identical wind turbines. Thus, the overall aggregated PDF of a wind farm remarkably influences the critical parameters including the expected power and energy, capacity factor, and the reliability metrics such as loss of load expectation (LOLE) and expected energy not supplied (EENS). Furthermore, the proposed approach is deployed for optimal allocation of wind energy in bulk power systems. Hence, two typical test systems are numerically analyzed to interrogate the performance of the proposed approach. The conducted survey discloses an over/underestimation of harvestable wind energy in the case of overlooking spatial distributions. Thus, inaccurate amounts of wind farm’s capacity factor, output power, energy and reliability indices might be estimated. Meanwhile, the number of wind turbines may be misjudged to be installed. However, the proposed approach yields in a fair judgment regarding the overall performance of the wind farm. Consequently, a reliable penetration level of wind energy to the power system is assured. Extra discussions are provided to deeply assess the promising merits of the founded approach.

Voltage Stability Investigation of the Egyptian Grid with High Penetration Level of Wind Energy

Voltage Stability Investigation of the Egyptian Grid with High Penetration Level of Wind Energy

Voltage Stability Investigation of the Egyptian Grid With High Penetration Level of Wind Energy During Steady State and Transient

Voltage Stability Investigation of the Egyptian Grid With High Penetration Level of Wind Energy During Steady State and Transient