【作者】 周璐；

【导师】 黄纯；

【作者基本信息】 湖南大学 ， 电气工程， 2010， 硕士

【摘要】 超/特高压输电线路是我国坚强智能电网的重要组成部分；距离保护由于具备受电网结构和系统运行方式影响较小等优点,在高压输电线路继电保护中得到了广泛应用。本文通过分析超/特高压线路故障信号特征,研究了距离保护稳态超越、暂态超越现象的产生机理,提出了新的故障信号分析方法和新的自适应距离保护判据。首先,对超/特高压输电线路距离保护中故障信号处理的常用算法进行分析和比较,针对超/特高压输电线路故障信号直流分量衰减缓慢、高频分量丰富的特点,应用prony算法拟合故障信号。为了减少噪声对prony算法的影响,采用奇异值分解(SVD)的方法确定prony算法的模型阶数,构造了SVD-prony算法。其次,鉴于超/特高压线路的稳态物理特征,通过分析超/特高压输电线路容易发生稳态超越的原因,探讨了工频变化量距离继电器在解决稳态超越方面的优势；通过对几种工频变化量距离继电器判据的分析,构造了工频变化量距离继电器的统一表达式；研究了负荷变化和保护范围的关系,建立自适应判据来改变工频变化量统一表达式的中间参数,以调整保护范围,达到更好地防止线路末端区外发生稳态超越的目的。再次,鉴于超/特高压线路的暂态物理特征,在分析超/特高压输电线路中容易发生暂态超越的原因的基础上,通过实时计算SVD-prony算法拟合误差,并根据拟合误差和电抗计算误差之间的关系,建立整定阻抗的修正曲线；依据修正曲线,构造一个基于SVD-prony算法的拟合误差的自适应判据,利用该判据自适应地调整动作门槛,避免线路末端区外发生暂态超越,提高区内故障时保护的速动性。运用ATP软件对超/特高压线路短路故障进行建模和仿真,得到各种故障情形下的电压、电流信号；基于MatLab平台应用SVD-prony算法对故障信号进行参数估计,并对自适应保护判据进行验证。仿真结果表明,本文所提出的SVD-prony算法及为解决暂态超越和稳态超越而建立的自适应判据能够更好地适应系统运行方式和故障状态的变化,使得超/特高压输电线路距离保护的性能更优。更多还原

【Abstract】 EHV/UHV transmission line plays an important role in strong smart grid; distance protection has got widespread application in high voltage transmission line relay protection due to its characteristics of being less affected by the system operation mode and grid structure. By analyzing fault signal characteristics in EHV/ UHV transmission line and studying on the mechanism of the emergence of steady-state overreach and transient overreach, this paper provides a new fault signal analysis algorithm and a new adaptive distance protection criterion.First, several distance protection algorithms are analyzed and compared. Considering the fault signal with slow decayed DC component and rich high frequency components in EHV/UHV transmission line distance protection, prony algorithm is adopted to fit fault signal. In order to reduce the impact of noise on prony algorithm, the order of prony algorithm is determined by Singular Value Decomposition(SVD) method, and SVD-prony algorithm is constructed.Second, in view of the steady-state physical characteristic in EHV and UHV transmission line, the reason why steady-state overreach occur is introduced exactly and the advantage of employing power frequency distance relays in solving steady-state overreach is penetrated. Based on analyzing several power frequency distance relays criterion, unified expression of power frequency distance relays is established. By studying on the relationship of the load change and protection area, an adaptive strategy is established to adjust protection area by changing the parameters, thus, it can avoid steady-state overreach at the end of transmission line.Third, considering the transient physical characteristics in EHV and UHV transmission line, the reason why transient overreach occur is introduced. By calculating the fitting error of SVD-prony, and according to the relationship between fitting error and the calculation reactance error, amending curve is constructed. According to the amending curves, the distance protection settings have been amended adaptively to avoid transient overreach, so it can make protection more quickly.An EHV and UHV power system are built using simulation tool ATP, from which we can get voltage and current signal in various fault conditions. Based on MatLab platform, the parameters of fault signals are estimated using SVD-prony algorithm, then, the adaptive criteria is validated. The simulation results show that SVD-prony algorithm and adaptive criterion used to solving steady-state overreach and transient overreach can adapt to the changes of the operational mode and fault state, therefore, it makes the performance of the distance protection in EHV and UHV transmission line better.更多还原