大规模风电接入的概率潮流研究

发布时间：2019-05-26 22:13

【摘要】：风力发电技术日益成熟,在我国风电呈现出大规模并网的形势,将众多风电机组汇集后分散接入电网。然而在风电资源极其丰富的地区存在"弃风"现象,风电场满发时的发电量不能全部并入电网,即电网对风电场发电功率的接纳能力受限于联络线的传输容量,同时邻近的风电场出力之间表现出强相关性。若大规模风电接入电网,将增加系统潮流的不确定性,严重影响电力系统安全运行。本文提出了一种计及风电出力相关性和电网接纳能力的概率潮流计算方法,并将其应用到宁夏电网实际工程项目和电力系统静态安全分析中。(1)提出了一种考虑电网接纳能力的概率潮流计算。基于考虑电网对风电接纳能力的风电出力模型,其概率分布是以分段函数的形式表示,提出了一种改进拉丁超立方抽样法。算例结果表明所提出的概率潮流计算方法克服了传统拉丁超立方抽样无法对非规则概率分布随机变量进行抽样的不足,能在抽样规模大幅减小的情况下得出与基于随机抽样的蒙特卡洛模拟法相近的计算结果,并对比分析了单风电场接入下风电出力概率分布不同时支路潮流概率分布的差异性。(2)提出了一种计及风电出力相关性和电网接纳能力的概率潮流计算。研究了基于历史数据和Copula理论的风电出力相关性分析方法,提出了一种同时适用于已知和未知概率分布风电出力模型的改进拉丁超立方抽样法。所提出的概率潮流计算既考虑了电网接纳能力,又可以很好地处理不同风电场出力之间的非线性相关性。算例结果表明本文提出方法在精度和速度上有较大优势,也说明了计及风电出力相关性的必要性。(3)结合宁夏电网实际工程项目,将本文提出的计及风电出力相关性和电网接纳能力的概率潮流计算应用于宁夏电网运行状态分析中,系统运行结果验证了本文所提出的方法可以高效准确地分析大规模风电接入宁夏电网的概率潮流分布特性,并基于MATLAB软件的GUI开发了宁夏电网概率潮流计算可视化分析系统。(4)将本文提出的概率潮流计算方法应用于电力系统静态安全分析。为了加快分析速度,提出了一种基于支路可用容量熵的预想事故排序指标和基于多场景下的排序方法。算例结果表明该方法可以准确地对系统静态安全进行评估,快速找出潜在弱点。
[Abstract]:Wind power generation technology is becoming more and more mature, and wind power is connected to the grid on a large scale in our country, and many wind turbines are connected to the power grid. However, in areas where wind power resources are extremely rich, there is a phenomenon of "abandoning wind". When the wind farm is full of electricity, the power generated by the wind farm can not be fully integrated into the power grid, that is to say, the acceptance capacity of the grid to the power generation of the wind farm is limited by the transmission capacity of the tie line. At the same time, there is a strong correlation between the output of adjacent wind farms. If large-scale wind power is connected to the power grid, the uncertainty of system power flow will be increased, and the safe operation of power system will be seriously affected. In this paper, a probabilistic power flow calculation method, which takes into account the correlation of wind power output and the acceptability of power grid, is presented. It is applied to the actual engineering project of Ningxia power grid and the static security analysis of power system. (1) A probabilistic power flow calculation considering the acceptability of power grid is proposed. Based on the wind power output model considering the capacity of power grid to accept wind power, the probability distribution is expressed in the form of piecewise function, and an improved Latin hypercubic sampling method is proposed. The results of an example show that the proposed probabilistic power flow calculation method can overcome the deficiency that the traditional Latin hypercubic sampling can not sample the random variables of irregular probability distribution. The calculation results are similar to those of the Monte Carlo simulation method based on random sampling when the sampling size is greatly reduced. The difference of power flow probability distribution of different branches under single wind farm access is compared and analyzed. (2) A probabilistic power flow calculation considering the correlation of wind power output and the acceptance capacity of power grid is proposed. The correlation analysis method of wind power output based on historical data and Copula theory is studied, and an improved Latin hypercubic sampling method is proposed, which is suitable for both known and unknown probability distribution wind power output models. The proposed probabilistic power flow calculation not only takes into account the acceptability of the power grid, but also can deal with the nonlinear correlation between the outputs of different wind farms. The results of an example show that the method proposed in this paper has great advantages in accuracy and speed, and also shows the necessity of taking into account the correlation of wind power output. (3) combined with the actual engineering project of Ningxia Power Grid, The probabilistic power flow calculation, which takes into account the correlation of wind power output and the acceptance capacity of power grid, is applied to the operation state analysis of Ningxia power grid. The operation results of the system verify that the method proposed in this paper can efficiently and accurately analyze the probabilistic power flow distribution characteristics of large-scale wind power connected to Ningxia power grid. A visual analysis system for probabilistic power flow calculation of Ningxia power grid is developed based on GUI of MATLAB software. (4) the probabilistic power flow calculation method proposed in this paper is applied to the static security analysis of power system. In order to speed up the analysis, an expected accident sorting index based on branch available capacity entropy and a sorting method based on multi-scene are proposed. The results of numerical examples show that the method can accurately evaluate the static security of the system and quickly identify the potential weaknesses.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614;TM744

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