Penetration Level Of Wind Energy Research Articles

Assessment of the Role and Value of Frequency Response Support From Wind Plants

High penetration of wind generation causes concerns over frequency stability, as currently wind plants do not provide frequency response support. Extensive research has been conducted to investigate alternative designs of controllers to facilitate the provision of synthetic inertia and primary frequency response from wind plants. However, frequency response support from wind plants differs from that provided by conventional plants and its impact on the system's economic performance is not yet fully understood. In this context, this paper develops a novel methodology to incorporate the frequency response support from wind plants into generation scheduling, thus enabling the benefits of alternative control strategies to be quantified. Studies are carried out on the future Great Britain power system with different wind energy penetration levels and frequency response requirements. The impact of the uncertainty associated with the quantity of wind plants being online and the energy recovery effect are also analyzed. The results demonstrate that the benefits of frequency response support from wind plants may be significant, although these are system specific. The proposed model could also inform the development of grid codes, market mechanisms, and business cases associated with the frequency response support from wind plants.

Dynamic Demand Control of Electric Vehicles to Support Power Grid With High Penetration Level of Renewable Energy

Electric vehicles (EVs) have become increasingly popular over the last few years and are considered as an important means to mitigate air pollution problems in big cities around the world. With their onboard batteries, EVs also present an opportunity to serve as a demand response tool in supporting future smart grid where there is usually high penetration level of renewable energy (RE) sources. In this study, a novel dynamic demand control (DDC) has been developed to coordinate the charging and discharging of EVs according to the frequency deviation signal to deal with intermittent RE generation. Furthermore, in our work, customers’ requirements and satisfaction are strictly guaranteed through the introduction of a new term called Urgency Index. The merits of this scheme are its simplicity, efficiency, robustness, and readiness for practical applications. The effectiveness of the proposed control scheme is demonstrated by computer simulations of a power system with high penetration level of wind energy.

Assessing the Effective Parameters on Operation Improvement of SCIG based Wind Farms Connected to Network

As the penetration level of wind energy in power system increases, stable operation of power system would get impacted by wind turbine's characteristics. The stability issue derived from this fact that the squirrel cage induction generators (SCIG) used in these turbines potentially would cause voltage drop and voltage stability problems in network, regarding to its reactive power absorption tendency. Thus, detection of effective parameters in increment and reduction of unstability occurrence probability could make SCIG based wind farm predictable and eventually cause improvement in voltage stability margin of whole of power system. In this paper, effective factors of wind farm operation connected to the network are assessed and studied in two sections. The first section includes parameters which depend upon substantive and functional characteristics of induction generator and could threat the stability of power system. The second section containing such parameters and characteristics of power system as which are able to affect the stable operation of SCIGs and can be lead to instability in whole of the power system. Eventually reactive power has been identified as more effective option in system designing. The studies are concentrated on voltage stability and small signal stability. In order to make the results more practical, the 660KW inductive generator which is widely used in Iran is studied in this paper.

Investigation of Connecting Wind Turbine to Radial Distribution System on Voltage Stability Using SI Index and <i>λ</i> -<i> V </i> Curves

The growth of wind energy penetration level in distribution system raises the concern about its impact on the operation of the power system, especially voltage stability and power loss. Among the major concerns, this paper studied the impact of connecting wind Turbine (WT) in radial distribution system with different penetration levels and different power factor (lead and lag) on power system voltage stability and power loss reduction. Load flow calculation was carried out using forward-backward sweep method. The analysis proceeds on 9- and 33-bus radial distribution systems. Results show that voltage stability enhancement and power loss reduction should be considered as WT installation objective.

Integrating battery banks to wind farms for frequency support provision–capacity sizing and support algorithms

The expected high penetration levels of wind energy in power systems require robust and practical solutions to maintain typical conventional systems performance. Wind farms (WFs) positive contribution in eliminating grid frequency deviations is still a grey area, especially when they replace considerable conventional generation capacities. This paper offers a sizing algorithm to integrate storage battery banks (SBs) in WFs to provide feasible power support during frequency events. This algorithm determines the required rated power and capacity of each SB inside a WF according to several constrains, including wind speed (WS) characteristics at WF location. The size of the SB is based on a statistical study for the amounts of rejected wind power, and the events of low wind production. The offered operation algorithm controls the SB charging, discharging, and standby modes based on the acquisition of different dynamic variables, for example, WF output, load demand, and storage cells' state of charge. The operation algorithm aims to mitigate frequency drops and rejected wind power and to maintain the battery lifetime. Both algorithms are applied on a defined sector from a genuine conventional system merged with real WS chronological records at certain locations which are candidates to host WFs. Results reveal the positive influence of SB involvement on frequency excursions clearance; in addition, wasted wind energy is mitigated since wind turbines de-loading techniques are avoided and some rejected wind power is utilized to charge the installed SBs. Precise models are integrated through MATLAB and Simulink simulation environment.

Utilising stored wind energy by hydro‐pumped storage to provide frequency support at high levels of wind energy penetration

Wind farms (WFs) contribution in frequency deviations curtailment is a grey area, especially when WFs replace large conventional generation capacities. This study offers an algorithm to integrate hydro-pumped storage station (HPSS) to provide inertial and primary support, during frequency drops by utilising stored wind energy. However, wind turbines follow maximum power tracking, and do not apply frequency support methods, thus the wasted wind energy is mitigated. First, HPSS rated power and energy capacity are determined based on several givens, including wind speed and load characteristics. Thus, HPSS major aspects are estimated [e.g. pump(s), reservoir layout and generator(s)]. Second, offered algorithm coordinates energy storage, and releasing through several dynamic and static factors. HPSS output is continuously controlled through a timed approach to provide frequency support. A hypothetical system is inspired from Egyptian grid and real wind speed records at recommended locations to host WFs. Case studies examine the algorithm impact on frequency recovery, at 40% wind power penetration. The responses of thermal generation and HPSS are analysed to highlight the influence of tuning the parameters of the proposed algorithm. The assessment of several frequency metrics insures the positive role of HPSS in frequency drops curtailment. Simulation environments are MATLAB and Simulink.

Optimal operation of power system incorporating wind energy with demand side management

The high penetration of the wind energy in the power systems raises some issues such as ramping and mismatch between the wind power and power demand. One of the possible solutions to these issues is the demand side management (DSM). In this paper, dynamic economic dispatch (DED) incorporating different penetration levels of wind energy and utilizing the DSM is proposed to solve the issues related to high penetration of wind energy. The effect of utilizing the DSM on the operation cost with different test cases is discussed. The General Algebraic Modeling System (GAMS) using BARON as a solver and genetic algorithm (GA) with hybrid function are used to solve the proposed DED model and a comparison between them is assessed. The proposed model is applied to a six units’ generation system to test the effectiveness of the proposed model.

The technical potential for wind energy in Illinois

The demand for harnessing clean, renewable energy sources like wind energy has increased greatly over the past decade due to a confluence of political and environmental concerns. Although wind energy is recognized as a promising source of clean energy, some decision-makers are asking how much wind energy should ultimately be installed. As the level of installed wind energy capacity increases, it is possible that at some point the aggregated generation mix could produce electrical power exceeding electrical demand. This situation could require excessive generator curtailment. In this investigation several different criteria are explored to develop an optimum level of in-state wind energy penetration into the existing generation infrastructure. In this way, the benefit to society may be maximized. Three scenarios are studied: 1) a scenario in which the wind carve-out remains at 75% of the state's Renewable Portfolio Standard, 2) a scenario in which all of the wind energy that is generated must be fully utilized, and 3) a scenario in which wind energy is allowed to be curtailed at a rate equal to the rate that energy is used internally at thermal generation plants.

NSGA-II based optimal control scheme of wind thermal power system for improvement of frequency regulation characteristics

Abstract This work presents a methodology to optimize the controller parameters of doubly fed induction generator modeled for frequency regulation in interconnected two-area wind power integrated thermal power system. The gains of integral controller of automatic generation control loop and the proportional and derivative controllers of doubly fed induction generator inertial control loop are optimized in a coordinated manner by employing the multi-objective non-dominated sorting genetic algorithm-II. To reduce the numbers of optimization parameters, a sensitivity analysis is done to determine that the above mentioned three controller parameters are the most sensitive among the rest others. Non-dominated sorting genetic algorithm-II has depicted better efficiency of optimization compared to the linear programming, genetic algorithm, particle swarm optimization, and cuckoo search algorithm. The performance of the designed optimal controller exhibits robust performance even with the variation in penetration levels of wind energy, disturbances, parameter and operating conditions in the system.

Real-Time Wavelet-Based Coordinated Control of Hybrid Energy Storage Systems for Denoising and Flattening Wind Power Output

Since the penetration level of wind energy is continuously increasing, the negative impact caused by the fluctuation of wind power output needs to be carefully managed. This paper proposes a novel real-time coordinated control algorithm based on a wavelet transform to mitigate both short-term and long-term fluctuations by using a hybrid energy storage system (HESS). The short-term fluctuation is eliminated by using an electric double-layer capacitor (EDLC), while the wind-HESS system output is kept constant during each 10-min period by a Ni-MH battery (NB). State-of-charge (SOC) control strategies for both EDLC and NB are proposed to maintain the SOC level of storage within safe operating limits. A ramp rate limitation (RRL) requirement is also considered in the proposed algorithm. The effectiveness of the proposed algorithm has been tested by using real time simulation. The simulation model of the wind-HESS system is developed in the real-time digital simulator (RTDS)/RSCAD environment. The proposed algorithm is also implemented as a user defined model of the RSCAD. The simulation results demonstrate that the HESS with the proposed control algorithm can indeed assist in dealing with the variation of wind power generation. Moreover, the proposed method shows better performance in smoothing out the fluctuation and managing the SOC of battery and EDLC than the simple moving average (SMA) based method.

Investigating the effect of high level of wind penetration on voltage stability by quasi-static time-domain simulation (QSTDS)

In this paper, the impact of increasing in wind energy penetration level on voltage stability is studied by utilizing quasi-static time domain simulation (QSTDS). Connecting a squirrel cage induction generator (SCIG)-based wind farm has an undesirable effect on the voltage stability in power system, especially when this connection is accompanied with increase in the level of wind generation. Due to the asynchronous operation of induction machine, the increment of wind power generation will be possible only by absorption of more reactive power. Increasing in the power reactive consumption of induction generator leads to reduction of voltage in the bus of common connection between wind farm and the grid. Under these conditions, if the reactive power absorption of wind farm is not managed efficiently it would result in voltage instability of the grid. In this paper, it is shown that using static Var compensator (SVC) and static synchronous compensator (STATCOM) has improved the voltage stability of the system and leads to desirable performance of the wind farms.

Investigation of Critical Factors Affecting Dynamic Stability of Wind Generation Systems with Permanent Magnet Synchronous Generators

This paper presents an analysis to investigate the critical factors which affect the dynamic stability of wind energy conversion systems (WECSs) with permanent magnet synchronous generators (PMSGs). In this paper, at first the detail mathematical model of a WECS with a PMSG is developed and then the modal analysis technique is used to identify the critical factors. The sensitivity of these critical factors on the dynamic stability of WECSs with PMSGs, is analyzed in terms of damping ratio with changes in critical factors. The proposed approach is tested on a WECS with single PMSG for different level of wind energy penetration.

Static synchronous compensator sizing for enhancement of fault ride‐through capability and voltage stabilisation of fixed speed wind farms

High penetration level of wind energy affects the generation profile of the power systems, which impose more stringent connection requirements of wind farms. The ability of wind power plant to remain connected during grid faults is very important to avoid cascaded outages because of power deficit. FACT devices are considered to be a key technology to accomplish these requirements. The implementation of three-level inverter based on a static synchronous compensator (STATCOM) for the improvement of the ride-through and stability of fixed speed wind farms is analysed here. This brings the challenges for system planner to determine the appropriate STATCOM rating. This study provides a simple approach to evaluate the STATCOM rating for voltage-level regulation at the point of common coupling around its pre-specified value. Vector current control is used as robust control to inject the required reactive power from STATCOM. This study emphasizes also on the analysis of torque speed curve to evaluate the induction generator speed limit and for defining the critical clearing time of the fault according to the selected STATCOM rating. Simulation results under fault conditions are performed to validate the enhancement of wind farm low-voltage ride-through capability and increasing the critical clearing time by installing STATCOM.

Smart Charging and Discharging of Electric Vehicles to Support Grid with High Penetration of Renewable Energy

High penetration of renewable energy to the grid may cause a number of problems such as supply and demand mismatch, voltage fluctuations and even network instability. Electric Vehicles (EVs) with on-board batteries are capable of supporting the grid with large integration of renewable energy sources by absorbing (charging) the excessive amount of energy and returning it (discharging) to grid when needed. This paper proposes a new smart control algorithm using the idea of Certainty Equavilent and Adaptive Control and a ”customer participating program” to coordinate both the charging and discharging of EVs to achieve the above objective. The advantages of the proposed algorithm come from its simplicity, robustness and hence a promising opportunity for real-life applications in future smart grid. The effectiveness of the proposed scheme is evident by the numerical simulations on a micro-grid system with high penetration level of wind energy

A solution to the generation scheduling problem in power systems with large-scale wind farms using MICA

This paper presents a novel solution, based on the Imperialistic Competition Algorithm (ICA), in order to determine the feasible optimal solution of the Generation Scheduling (GS) problem, in power systems with large scale wind farms. The reserve requirement, load balance and wind power availability constraints are considered in this work. In order to solve a highly constrained GS problem, a modified version of ICA is introduced to improve the initialing new countries and assimilation operators of ICA. The proposed MICA is applied on different test systems, with different wind energy penetration level. The results are compared with other methodologies and the comparison demonstrates the validity and efficiency of the proposed method, which results in near optimal schedules, while considering different equality and inequality constraints.

Wind farms dispatching to manage the activation of frequency support algorithms embedded in connected wind turbines

Wind energy development in power systems and their replacement for conventional generation plants are considered to be a two sided coin. Wind energy penetration process depends on two aspects, namely, the technical and economical impacts on power grid and electricity market. This paper focuses on the technical section and aims to solve a major problem related to the high wind energy penetration levels. This dilemma arises due to the intermittent nature of wind speed which mitigates its capabilities compared to conventional generation, especially in dealing with frequency drops. This research work focuses on a basic sector from this problem, particularly, dispatching the wind turbines, inside wind farms, during frequency drops mitigation. The proposed algorithm integrates several factors to determine the number of wind turbines which should contribute in system frequency recovery. Wind speed nature in the wind farm location, installed wind turbines types and their numbers are examples for these factors. However, this dispatching process is instantaneous and counts on other dynamic factors (e.g. average wind speed at wind turbine and frequency deviation severity). In addition, conventional generation is controlled based on wind farms reactions during frequency drops, likewise at normal operation. Certain zone from the Egyptian grid is integrated in this research work as a benchmark to apply the offered algorithm whereas real data for wind speeds and grid specifications are applied. MATLAB and Simulink are the implemented simulation environments.

Control and quantification of kinetic energy released by wind farms during power system frequency drops

High wind energy penetration levels in modern power systems draw attention towards wind farms expected role during frequency drops. Wind farms positive contribution required by system operators basically depends on the amount of kinetic energy stored in wind turbines rotating parts and how to manage it during frequency deviations elimination. This study presents an algorithm to estimate and control the quantity of extractable kinetic energy stored in a wind farm during frequency drops. Moreover, it manages stored kinetic energy release within a given time span to achieve positive participation in frequency drops clearance. The proposed method is based on tuning the tip speed ratio before and during the frequency drop according to several factors. The recovery time required by the wind turbine to retain its normal speed is also a function of several parameters including turbine inertia and the incoming wind speed. The proposed algorithm's impact on power system frequency is analysed by assessing the expected enhancement in frequency deviation. A hypothetical grid is considered as the benchmark including detailed modelling for wind speeds, wind turbine and wind farm to improve the creditability of the obtained results. Presented research work outcomes highlight the impact of wind farms replacement for conventional generators. Executed simulations proved that applying the proposed algorithm neutralises wind energy penetration influence on system frequency response, even more, it causes solid improvements unless the incident wind speed is too slow or the frequency drop is too high. Simulation environments are MATLAB and Simulink.

An Energy Management Strategy for a Wind Power Plant Based on Energy Storage and Wind Power Prediction

Wind energy is the most common and fastest-growing application of renewable energy in power systems. Wind power generation is an intermittent and unpredictable energy, therefore power system operators have to face some difficulties such as stability, reliability, power quality, etc. Wind forecast and energy storage techniques are used for system reliability, stability, and increasing the penetration level of wind energy. The aim of this study to find a new usable solution to reduce the energy balance funding and increase the system reliability. According to the results of the proposed system, system reliability has obtained 83% and the wind penetration level has increased by 9%. Additionally, balance cost is reduced for the mentioned system.

Increasing Wind Energy Penetration Level by Using Pumped Hydro Storage in Island Micro-Grid System

Ramea is a small island in southern Newfoundland. Since 2004, it has a wind-diesel hybrid power system to provide power for approximately 600 inhabitants. In this paper, wind speed data, load data, and sizing of pumped hydro system at Ramea, Newfoundland are presented. The dynamic model of wind turbine, pumped hydro system, and diesel generator are included in this paper. The dynamic model is simulated in SIMULINK/MATLAB to determine the system voltage and frequency variation and also to visualize different power outputs. Sizing of pumped hydro system indicates that a 150-kW pumped hydro storage system can be installed in Ramea to increase the renewable energy fraction to 37% which will reduce non-renewable fuel consumption on this island. Also, it is found that a pumped hydro energy storage system for Ramea is a much better choice than a hydrogen energy storage system. Such a system will have a higher overall efficiency and could be maintained using local technical expertise, therefore, a more appropriate technology for Ramea.

Performance evaluation and accuracy enhancement of a day-ahead wind power forecasting system in China

Abstract Wind power forecasting system is useful to increase the wind energy penetration level. Latest statistics show that China has been the biggest wind energy market throughout the world. However, few studies have been published to introduce the wind energy forecasting technologies in China. This paper presents the performance evaluation and accuracy enhancement of a novel day-ahead wind power forecasting system in China. This system consists of a numerical weather prediction (NWP) model and artificial neural networks (ANNs). The NWP model is established by coupling the Global Forecasting system (GFS) with the Weather Research and Forecasting (WRF) system together to predict meteorological parameters. In addition, Kalman filter has been integrated in this system to reduce the systematic errors in wind speed from WRF and enhance the forecasting accuracy. The numerical results from a real world case are proven the effectiveness of this forecasting system in terms of the raw wind speed correction and wind power forecasting accuracy. The Normalized Root Mean Square Error (NRMSE) has a month average value of 16.47%, which is an acceptable error margin for allowing the use of the forecasted values in electric market operations. This forecasting system is profitable for increasing the wind energy penetration level in China.