Advanced Materials Research Vols. 1070-1072

Abstract: Wind energy is clean and renewable energy with rich resources. As one of the most promising green energy, wind power has become an important part of the electricity supply. But there are still many technical problems to be solved related to wind power generation and integration, because it may have significant impact on safe and stable operation of the power grid. Therefore, the doubly-fed wind generator and direct-driven permanent-magnet wind power generator are studied. Their models are built in PSCAD/EMTDC for electromagnetic transient simulation, in order to study the characteristics of their short circuit fault current, as well as the impact on the relay protection of the wind power system. The research outcomes provide a reference and basis to wind power failure characteristics research.

Abstract: If a doubly fed induction generator (DFIG) were to penetrate into a distributed generation system successfully, it should be able to adapt to autonomous and unbalanced conditions. To dealing with this situation, an indirect stator flux orientation (ISFO) control strategy with the droop method is introduced to cope with the positive sequence components of DFIG and provide the system with a solid voltage and frequency support. Meanwhile, a negative sequence droop is also proposed for DFIG so as to achieve a reasonable sharing of unbalanced loads and ensure the power supply quality at the point of common coupling (PCC). Finally, simulation results are provided to demonstrate the correctness of the suggested control strategy under autonomous and unbalanced conditions when DFIG is connected in parallel with a converter.

Abstract: Wind turbine power characteristic curve is not only an important indicator to assess the performance of wind turbine and evaluate the power generation performance, but also an important factor of impacting the wind power prediction accuracy. In this article, an identification method of the wind turbine power characteristic curve based on the genetic algorithm is proposed. With the piecewise linearization method, the wind turbine power characteristic curve is divided into several sections that can be described by linear or quadratic functions. Data preprocessing is used to filter the abnormal points in the original data. The distance from the wind turbine operating points to the power characteristic curve is selected as the fitness function. The identification process is to look for the parameters of the linear or quadratic curves that have the shortest distance to the massive operating points. The effectiveness of the algorithm is verified through the computation of a wind farm data.

Abstract: As wind is random, intermittent and instability, with continual installation of wind farms, the impact of large scale wind farm on power system has become an important issue for integration and operation of wind farm. Aiming at studying the transient stability of district grid containing high proportion of wind power, numerical simulations with BPA for an actual district grid of China Southern Power Grid are presented. In these simulations, the interaction between the large-scale wind farm and traditional thermal power plants (TPPs) is investigated taking the different operating modes and fault location into account. The critical clearing time (CCT) is adopted as the measurable indicator to assess the interaction.

Abstract: Power system vulnerability is one new concept for power security as the extend of security in recent years. At present, the power system vulnerability research has obtained stage accomplishment. Meanwhile, the randomness and intermittence of the wind lead to the wind power output unsteady. It not only has a bad influence on the power system, but also makes wind farm vulnerability even more obvious. Based on this, vulnerability assessment is applied to large-scale wind farm in this paper. Vulnerability indexes of the bus in large-scale wind farm are put forward and prevention measures are also given and it will has reference meaning to the security enhance of both grid and wind farm.

Abstract: Based on wind speed data of 13 meteorological stations in 1958-2012,Mann-Kendall nonparametric test methods was been used to study on wind speed changes in Hexi Corridor.Spatial and temporal characteristics of seasonal and monthly wind speed changes was examined. (1) The maximum wind speed appeared in the higher elevations of study area, such as Wushaoling and Mazongshan station. From east to west mean wind speed increased in Hexi Corridor.For nearly 50 years wind speed had showed decreasing trend. (2)In each season Spring with an maximum mean wind speed was 3.4m/s,the Summer mean wind speed was 2.9 m/s,Autumn mean wind speed was 2.6 m/s,the mean Winter wind speed was 2.8m/s.The seasonal wind speed mainly had decline trend, each station.has different characteristics trends (3) Mean wind speed in each month was greater than 2.5m/s,maximum monthly wind speed appeared in April was 3.5m/s,the minimum wind speed appeared in the September-October was 2.53m/s,the wind speed in March,April and May was greater than the November month,December,January.In addition to Mazongshan and Wushaoling,other station monthly wind speed showed a decreasing trend.Monthly mean wind speed in Jiuquan,Dingxin and Zhangye was slow decreasing trend.Anxi,Yumen wind decreasing trend were more obvious.(4)Wind decreasing trend will have a significant impact on wind energy, wind speed changes and wind energy should be evaluated in the future.

Abstract: In order to make better use of wind resources and reduce abandoned wind and improve capacity of grid accepting wind power ,this paper studies the feasibility of storing abandoned wind based on using the PHS(Pumped Hydro System). The paper has constructed model of Wind – PHS co-generation system based on operating characteristics of various types of power. Under the constraints of system demands and the technical characteristics of various types of power, the model use the minimum total operation cost of the system as the objective function, then use real coding genetic algorithm simulation to solve the problem. The results show that the use of pumped storage power station can not only reduce the abandoned wind, and the economic benefits of storage abandoned wind are better than the economic benefits of without wind abandoned. At last with evaluation and factors influencing the analysis, the conclusion that the optimal capacity of pumped storage power station in the system is expected to providing a reference which can help for the rational allocation of resources.

Abstract: A real-time dispatch (RTD) model for wind power incorporated power system aimed at maximizing wind power utilization and minimizing fuel cost is proposed in this paper. To cope with the prematurity and local convergence of conventional particle swarm optimization (PSO) algorithm, a novel adaptive chaos quantum-behaved particle swarm optimization (ACQPSO) algorithm is put forward. The adaptive inertia weight and chaotic perturbation mechanism are employed to improve the particle’s search efficiency. Numerical simulation on a 10 unit system with a wind farm demonstrates that the proposed model can maximize wind power utilization while ensuring the safe and economic operation of the power system. The proposed ACQPSO algorithm is of good convergence quality and the computation speed can meet the requirement of RTD.

Abstract: The offshore wind farms have many advantages over the onshore ones: they are not affected by the terrain, ground vegetation, buildings and other landscape features, so they have stronger and steadier wind, higher wind power density, smaller turbulence intensity and other advantages. Therefore, offshore wind power becomes the developing trends of wind power industry nowadays. However, its development faces the challenge of how to assess offshore wind resources accurately. It is difficult to get accurate, long-term, large-scale measured data on sea, and the nearshore observations cannot be substitute for the offshore wind conditions directly. This paper applies the NCEP CFSR reanalysis data (combines with the WMO marine observation data) to research the offshore wind resource assessment of China. We find that CFSR reanalysis data is consistent with the observation data, and it can provide a reference for China offshore wind resource assessment. The result of China offshore wind resource distribution is obtained finally.

Abstract: Detached eddy simulation (DES) with wall function was used in the flow simulation over complex terrain. Bolund Island with an almost vertical upstream escarpment was simulated, which has abundant measurements. Different density grids with the same size domain were employed. Flow structure details and good results can be obtained when the grid size is a twentieth or smaller than the height of the island in large separation region, when using central scheme. DES has better performance than RANS in large separation region.