Impact Of Wind Power Integration Research Articles

A Low-Frequency Oscillation Suppression Method for Regional Interconnected Power Systems with High-Permeability Wind Power.

With the integration of large-scale wind power into the power grid, the impact on system stability, especially the issue of low-frequency oscillations caused by small disturbances, is becoming increasingly prominent. Therefore, this paper proposes a damping quantitative analysis method for regional interconnected power systems incorporating large-scale wind power. Using the cross-entropy particle swarm optimization (CE-PSO) algorithm, the control parameters of wind turbines are optimized to suppress low-frequency oscillations in interconnected systems. The method begins with the state equation of the interconnected power system in two regions; it deduces the characteristic polynomial of the interconnected system, including wind farms, and takes into account the influence of wind power integration on the electrical connectivity of the system. Subsequently, the influence of wind turbine control parameters on the system is quantified, and a quantitative analysis model of the impact of wind power integration on system damping characteristics is constructed. Based on this, an optimization model for wind turbine control parameters is established, and the CE-PSO algorithm is utilized to achieve suppression of low-frequency oscillations in interconnected power grids with wind power integration. Finally, the accuracy and effectiveness of the proposed method are verified through a typical electromagnetic transient simulation model of the two-region interconnected power system.

Research on Mathematical Model of Energy Storage Assisted Wind Turbine Frequency Regulation Control Strategy

Abstract This paper proposes an improved frequency regulation strategy for the Doubly-Fed Induction Generator (DFIG) to mitigate the impact of wind power integration on system frequency. An energy storage system is used on the wind side to participate in the frequency regulation. The influence of wind power integration on the power system frequency is analyzed and an improved frequency control strategy for the DFIG is proposed. A control strategy for energy storage devices to support wind turbine frequency control is proposed. An energy storage device model is established that considers power correction based on the state of charge to avoid excessive charging and discharging. According to the operating state of the DFIG, a control strategy for the frequency regulation of the energy storage device is proposed. According to different wind speeds, a control strategy is proposed for the participation of the joint wind storage system in the frequency regulation. This control strategy can provide frequency support to the system when the wind turbine cannot participate in frequency regulation according to the different operating conditions of the wind turbine. After the wind turbine uses the improved frequency control strategy, it accelerates the recovery of the DFIG rotor speed while avoiding a secondary drop in the system frequency. In addition, when the energy storage device has a poor state of charge and the system frequency is good, it charges to restore the state of charge.

Investigating the Impact of Wind Power Integration on Damping Characteristics of Low Frequency Oscillations in Power Systems

This paper investigates the impact of doubly-fed induction generator (DFIG) wind farms on system stability in multi-generator power systems with low-frequency oscillations (LFOs). To this end, this paper establishes the interconnection model of the equivalent generators and derives the system state equation. On this basis, an updated system state equation of the new power system with integrated wind power is further derived. Then, according to the updated system state equation, the impact factors that cause changes in the system damping characteristics are presented. The IEEE two-area four-machine power system is used as a simulation model in which the LFOs occur. The simulation results demonstrate that the connection of wind power to the power feeding area (PFA) increases the damping ratio of the dominant mode of inter-area oscillation from −0.0263 to −0.0107, which obviously improves the system stability. Furthermore, the wind power integration into PFA, as the connection distance of the wind power increases, gradually decreases the damping ratio of the dominant mode of the inter-area oscillation to −0.0236, approaching that of no wind power in the system. Meanwhile, with the increase in the wind power output capacity, the damping ratio of the dominant mode of the intra-area and inter-area oscillation increases, and the maximum damping ratios reach 0.1337 and 0.0233, respectively.

Norton’s current theorem based online voltage stability analysis for wind connected power grid

The impact of wind power integration on power system voltage stability has received extensive attention recently. A new voltage stability H-index based on the Norton’s current distribution law is established, which could be quickly calculated by phasor measurement unit (PMU) data. For steady-state analysis, the voltage stability margin could be directly assessed by computing the difference between H-index and 1. Applicability of the proposed H-index is validated in the case of reverse power flow, i.e. the active power is transmitted from wind farms to the point of common coupling (PCC). Then, the characteristics of H-index with increased wind power are analyzed. Based on the relationship between H-index and wind farm current injection, an online voltage stability monitoring method is presented. In this monitoring process, three important currents are proposed to be mainly monitored along with the H-index, namely the ‘worry current’, ‘transition current’ and ‘limit current’. Therefore, the voltage stability analysis and control strategies can be implemented according to the monitored currents and H-index. Effectiveness of the proposed online voltage stability analysis method is further verified by simulation results performed in an improved 39-bus system.

A summary of impacts of wind power integration on power system small-signal stability

Wind power has been increasingly integrated into power systems over the last few decades because of the global energy crisis and the pressure on environmental protection, and the stability of the system connected with wind power is becoming more prominent. This paper summaries the research status, achievements as well as deficiencies of the research on the impact of wind power integration on power system small-signal stability. In the end, the further research needed are discussed.

Transient Stability Study of Power System with Large-Scale Wind Farm Integration

Large-scale wind power integration has become the current development trend of the power system. Large-scale wind power integration can change the original structure and characteristics of the system. Thus, it’s necessary to analyse the transient stability of power system which contains wind power, and to study the controlling strategy for improving the transient stability of power system. Based on EEAC, this paper studies the transient stability of the power system which contains wind power system theoretically, proposes the calculation method for accelerating area, decelerating area and margin, and illustrates the impact of wind power integration on the transient stability with power angle curve. Furthermore, this paper studies the modeling and simulation, and the experimental results prove the correctness of the theories.

Impact of Large-Scale Wind Power Integration on Small Signal Stability Based on Stability Region Boundary

Up until now, study results on the impact of large-scale wind power integration on small signal stability have often been in conflict. Sometimes, the conclusions are even completely opposite, making people unable to agree on which is right. The reason behind this phenomenon is that most of these studies are based on a certain grid and typical working conditions, so conclusions are reached by comparing changes in oscillation mode, one by one. This study method lacks a broader perspective, and often reflects only a part of the grid conditions. However, the small signal stability region boundary describes the critical operating range of power system small signal stability as a whole, making possible an overall evaluation of the system from a more macro perspective. Thus it is more suitable for analysis of the impact of large-scale wind power integration on small signal stability. Based on the above, using the model of wind farm integration to the single-machine infinite bus power system, this paper studies the impact of wind power integration scale and the coupling strength with synchronous generator on small signal stability through the comparison of the stability region boundaries, thus providing a new method and support for analyzing the impact of wind power integration on small signal stability.

Study of System Stability Based on the Combination of Low Voltage Protection and Security Automatic Device

Large disturbance stability of the system was greatly affected by the way of a lot of wind power centralized access to high voltage transmission network. We could use the traditional operation control scheme of controlling the wind farm and the nearby generator system operation output, but the wind farm and conventional power plant's interests would be seriously affected. Therefore, this paper put forward the control strategy by using the combination of low voltage protection and security automatic device. Large disturbance stability level could reach or close to the level before the wind, so as to minimize the impact of wind power integration on large disturbance stability of power system.

The impacts of wind power integration on sub-daily variation in river flows downstream of hydroelectric dams.

Due to their operational flexibility, hydroelectric dams are ideal candidates to compensate for the intermittency and unpredictability of wind energy production. However, more coordinated use of wind and hydropower resources may exacerbate the impacts dams have on downstream environmental flows, that is, the timing and magnitude of water flows needed to sustain river ecosystems. In this paper, we examine the effects of increased (i.e., 5%, 15%, and 25%) wind market penetration on prices for electricity and reserves, and assess the potential for altered price dynamics to disrupt reservoir release schedules at a hydroelectric dam and cause more variable and unpredictable hourly flow patterns (measured in terms of the Richards-Baker Flashiness (RBF) index). Results show that the greatest potential for wind energy to impact downstream flows occurs at high (∼25%) wind market penetration, when the dam sells more reserves in order to exploit spikes in real-time electricity prices caused by negative wind forecast errors. Nonetheless, compared to the initial impacts of dam construction (and the dam's subsequent operation as a peaking resource under baseline conditions) the marginal effects of any increased wind market penetration on downstream flows are found to be relatively minor.

Impact of Large-scale Wind Power Integration on the UFLS Scheme

This paper analyzes some major factors for the impact of wind power integration on power system dynamic frequency characteristics in theory. Combining with an actual grid, test scenarios with various scales of doubly fed induction generator (DFIG)-based wind power integration are formulated. Through simulation in the scenarios with FASTEST software, the impacts on the action of under frequency load shedding (UFLS) scheme are displayed in two aspects, the rate of change of frequency (ROCOF) and wind turbine generator own protection. Simulation result shows that the ROCOF will not affect the lock action of UFLS devices in the test system of this paper. Wind turbine generator protection may worsen frequency responses, so it is proposed to be in harmony with the design of UFLS scheme.

Analysis on Capacity of Wind Power Integration into Grid Based on Power Balance

Among all the factors influencing the capacity of wind power, peak regulation capability is commonly regarded as one of the most important constraint factors. From the perspective of peak regulation, the maximum peak-load regulating adequacy revised by the wind power characteristic coefficient is the limitation of the capacity of wind power. This paper proposes an assessment system on capacity of wind power integration into grid based on power balance. First of all, this assessment system takes the impact of wind power integration on the reserve capacity of the power system into consideration. Then calculate the reserve capacity based on power generation reliability index. Finally, evaluate the capacity of wind power based on the peak regulation capability of the units during the low load period. This paper analyses the capacity of wind power integration into Liaoning power grid based on power supply characteristics, load characteristics and peak-valley difference, and points out that the phenomenon of the “wind curtailment” is unavoidable. According to the specific situation of wind power limitation, this paper proposes measures to maximize the capacity of wind power.

Impact evaluation of wind power integration on power system using optimal power flow tool

With wind power integrated into a grid, the impact of wind power on a power system becomes a major concern. This paper mainly investigates the impact of wind power integration considering three issues – wind speed, number of wind turbines or wind power penetration (WPP) level. The impact of wind power is analysed by the optimal power flow (OPF) tool. First, the OPF model with WPP is constructed. The Levenberg–Marquardt method was then employed to solve the OPF problem. Finally, numerical simulations for the modified IEEE-30 node system with WPP are carried out. According to the simulation results, the impacts of wind speed, wind turbine number and WPP level on the static performance of the power system are systematically analysed.

Study on Loss Reduction of Large Scale Wind Power Concentrated Integration on Power System

In this paper, starting from the active network loss formulas and wind characteristics, it is pointed out the reactive power loss and reactive flow is the major impact of wind power integration on power system loss. The reactive power loss formulas of box-type transformer, main step-up transformer, wind farm collector line and connecting grid line are analyzed. Next the reactive power loss of transformer and transmission line is described in detail. Then put forward the loss reduction measures that installing SVC on the low voltage side of the main step-up transformer and making the doubly-fed wind generators send out some reactive power at an allowed power factor. Use the case of Gansu Qiaodong wind farm to verify the effectiveness of the proposed measures.

Impacts of Wind Power Integration on Generation Dispatch in Power Systems

The probabilistic nature of renewable energy, especially wind energy, increases the needs for new forms of planning and operating with electrical power. This paper presents a novel approach for determining the short-term generation schedule for optimal operations of wind energy-integrated power systems. The proposed probabilistic security-constrained optimal power flow (P-SCOPF) considers dispatch, network, and security constraints in pre- and post-contingency states. The method considers two sources of uncertainty: power demand and wind speed. The power demand is assumed to follow a normal distribution, while the correlated wind speed is modeled by the Weibull distribution. A Monte Carlo simulation is used to choose input variables of power demand and wind speed from their probability distribution functions. Then, P-SCOPF can be applied to the input variables. This approach was tested on a modified IEEE 30-bus system with two wind farms. The results show that the proposed approach provides information on power system economics, security, and environmental parameters to enable better decision-making by system operators.

Modeling and Simulation of the Impact of Wind Power Integration on Power Market Based on System Dynamics

The impact of wind power integration on power market is complex and time-dependent, and can be reflected by some key factors with causal feedback relationships. First, the System Dynamics feature of the impact of wind power integration on power market is analyzed; second, according to the causal feedback relationships among the key factors, the System Dynamics model of the impact of wind power integration on power market is established; on this basis, under the scenario of wind power integrated capacity increasing, the impacts of wind power integration on the power supply and demand, power price and costs in power market are dynamically simulated, and the validity of the System Dynamics model in this paper is verified.

Preliminary Impacts of Wind Power Integration in the Hydro-Quebec System

Recent studies undertaken by Hydro-Québec evaluate three aspects of the integration of wind generation on their system reliability/security. In an operations setting, the impacts on intra-hourly operating reserves and on extra-hourly balancing reserves are examined. On an operations planning horizon, the wind power capacity credit is evaluated for winter peak loading conditions, when very cold temperatures risk disabling part of the wind generation. Depending on the study, various mathematical tools were used to generate the statistical characteristics of the load and anticipated wind generation: time-series analysis, wind simulation at new/future wind plant sites, power system simulation and a posteriori determination of forecast errors. However, in each case the measure used to quantify the impact of wind generation has been related to the change in the variance of the total system uncertainty as a result of the addition of wind power generation.

Wind Integration in Power Systems: Operational Challenges and Possible Solutions

This paper surveys major technical challenges for power system operations in support of large-scale wind energy integration. The fundamental difficulties of integrating wind power arise from its high inter-temporal variation and limited predictability. The impact of wind power integration is manifested in, but not limited to, scheduling, frequency regulations, and system stabilization requirements. Possible alternatives are suggested for a more reliable and cost-effective power system operation. New computationally efficient methods for improving system performances by using prediction and operational interdependencies over different time horizons remain critical open research problems.

Statistics of wind farm power output: methods and applications

Statistical and spectral analysis techniques commonly used for characterising wind power output are reviewed. Techniques including correlation and linear regression, power spectra and the coherence function are explained using short example time series. The techniques are then applied to hourly wind speed data from three UK sites. Frequency diagrams of power output, of hourly and 4-hourly power output changes and generation duration curves are created. Statistics as a tool for studying the impact of wind power integration is discussed with focus on the measure of standard deviation.

Large‐scale wind power integration in Norway and impact on damping in the Nordic grid

AbstractThe Nordic energy market is in need of new power generation capacity. Norway is today in shortage of electrical energy, and the hydropower‐based system must rely on importing electrical power from its neighbours in a normal year of hydro inflow. One solution to this problem is to invest in new generation capacity, e.g. by integrating more wind power into the Norwegian grid. The Norwegian government has announced that 1000 MW of wind power will be installed in Norway by 2010, corresponding to an eventual energy production of approximately 3 TWh year−1. This article investigates the impact of wind power integration in Norway on the damping of interarea mode oscillations in the Nordic grid. The impact on the interarea mode oscillations is tested for various types of generators. Results from computer analyses of a simplified yet realistic equivalent of the Nordic power system are used to compute the interarea mode oscillations. Copyright © 2005 John Wiley & Sons, Ltd.