计及大规模风电并网的交直流电网连锁故障熵特征研究

Study on the entropy characteristics of cascading failure of AC/DC power grid considering large-scale wind power grid-connection

随着风电并网容量的不断提升和网内直流输电工程的日益增多,大量的电力电子化设备接入使得系统发生连锁故障模式以及演化过程出现了一些新的特征。从影响因素和发展过程等方面对比分析了电网传统连锁故障相继开断过程和计及大规模风电并网后的连锁故障过程的差异。在传统连锁故障潮流熵分析方法的基础上,引入了在相继开断中可能导致风机故障脱网的电压熵和频率熵,构建了其计算公式,并提出了评估连锁故障发展影响因素的综合熵向量,给出了连锁故障影响因素的判别方法与相应的流程,为对大规模风电并网后连锁故障的影响因素定量分析和评估提供了技术手段。通过对就地消纳型和外送型两种典型系统进行仿真,结果表明,所提的方法能够有效地反映电网发生连锁故障的原因以及发展过程。提出了相应的连锁故障防控措施。

With the continuous improvement of wind power grid-connected capacity and the increasing number of DC transmission projects in the network,a large number of power electronic equipment accesses have caused cascading failure modes in the system and some new features in the evolution process.This paper firstly compares and analyzes the difference between the traditional cascading failure of the power grid and the cascading failure process after taking into account the large-scale wind power grid-connection.The factors affecting the development of cascading failure are proposed.Secondly,based on the tidal current entropy analysis method of traditional cascading failure,the voltage entropy and frequency entropy which may cause the fan to be off-grid in successive breaking are introduced,and the calculation formula is constructed.A comprehensive entropy vector for evaluating the influencing factors of chain failure development is proposed.On this basis,the method for judging the influencing factors of cascading failure and the corresponding process are given,which provides a technical means for quantitative analysis and evaluation of the influencing factors of cascading failure after large-scale wind power integration.The simulation results show that the proposed method can effectively reflect the causes and development process of cascading failures in the power grid.Finally,the corresponding prevention and control measures of cascading failure are put forward.