Operation Of Wind Power Systems Research Articles

Lorenz Wind Disturbance Model Based on Grey Generated Components

In order to meet the needs of wind speed prediction in wind farms, we consider the influence of random atmospheric disturbances on wind variations. Considering a simplified fluid convection mode, a Lorenz system can be employed as an atmospheric disturbance model. Here Lorenz disturbance is defined as the European norm of the solutions of the Lorenz equation. Grey generating and accumulated generating models are employed to explore the relationship between wind speed and its related disturbance series. We conclude that a linear or quadric polynomial generating model are optimal through the verification of short-term wind speed prediction in the Sotavento wind farm. The new proposed model not only greatly improves the precision of short-term wind speed prediction, but also has great significance for the maintenance and stability of wind power system operation.

Application of Recurrence Plot to Wind Power Predictability Study under Different Sampling Intervals

The accurate prediction of wind power is an important way to improve the safety and economy of wind power system operation in large scale. On one side, the accuracy of wind power prediction depends on the characterized degree of accuracy for wind power fluctuations under the used prediction method. On the other side, it depends on the inherent degree of predictability in the characteristics of wind power fluctuations. This text will focus on the predictability of wind power, and use recurrence plot and recurrence rate to analyze it in the qualitative and quantitative view, and analyze change rule of recurrence plot and recurrence rate under different time scales. The real case of a wind farm has been analyzed to demonstrate that predictability of wind power will be poorer when the sampling interval becomes large.

A control scheme to fulfill the grid-code under various fault conditions in the grid-connected wind turbines

This paper presents systems and algorithms for the low-voltage ride-through control of wind power systems. The low-voltage ride-through (LVRT) requirement which is included in the grid-code regulates wind power systems to maintain their operation and supply reactive power during grid fault. When the grid fault arises some problems occur in wind power systems, such as over voltage and over current by transient conditions or surplus power. This paper proposes the LVRT strategy for a stable operation of wind power systems under the grid-fault condition. Proposed LVRT methods include a fault detection method, a design of dynamic braking resistor, and a flexible power control under various fault conditions. The simulation results show a validity of the proposed LVRT strategy with a 2-MW wind power system model.

Sequential quadratic programming particle swarm optimization for wind power system operations considering emissions

In this paper, a computation framework for addressing combined economic and emission dispatch (CEED) problem with valve-point effects as well as stochastic wind power considering unit commitment (UC) using a hybrid approach connecting sequential quadratic programming (SQP) and particle swarm optimization (PSO) is proposed. The CEED problem aims to minimize the scheduling cost and greenhouse gases (GHGs) emission cost. Here the GHGs include carbon dioxide (CO2), nitrogen dioxide (NO2), and sulphur oxides (SOx). A dispatch model including both thermal generators and wind farms is developed. The probability of stochastic wind power based on the Weibull distribution is included in the CEED model. The model is tested on a standard system involving six thermal units and two wind farms. A set of numerical case studies are reported. The performance of the hybrid computational method is validated by comparing with other solvers on the test system.

A Versatile Probability Distribution Model for Wind Power Forecast Errors and Its Application in Economic Dispatch

The existence of wind power forecast errors is one of the most challenging issues for wind power system operation. It is difficult to find a reasonable method for the representation of forecast errors and apply it in scheduling. In this paper, a probability distribution model named “versatile distribution” is formulated and developed along with its properties and applications. The model can well represent forecast errors for all forecast timescales and magnitudes. The incorporation of the model in economic dispatch (ED) problems can simplify the wind-induced uncertainties via a few analytical terms in the problem formulation. The ED problem with wind power could hence be solved by the classical optimization methods, such as sequential linear programming which has been widely accepted by industry for solving ED problems. Discussions are also extended on the incorporation of the proposed versatile distribution into unit commitment problems. The results show that the new distribution is more effective than other commonly used distributions (i.e., Gaussian and Beta) with more accurate representation of forecast errors and better formulation and solution of ED problems.

Dynamic Analysis and Experimental Study of MW Wind Turbine Gearbox

Gearbox is the core component of wind power train，the operating of which directly affects the normal operation of wind power system, therefore, it is of great significance to carry out the dynamic characteristics of wind power gear box. The finite element model of coupling system composed of gear-rotor-bearing-box is established. By using Lanczos method，natural frequencies and vibration models are obtained. According to the method of experimental modal analysis，the MW wind power gearbox is tested by using SIMO method, the result of which agrees with theoretical calculation. Both of them verify the reliability of finite modal analysis of MW wind power gearbox.