基于改进Hilbert谱分析的STATCOM并补线路保护方法

A Novel Method of Transient Protection for Shunt Compensated Lines Based on HHT Spectrum Analysis

希尔伯特-黄变换可以对非线性非平稳信号的特征进行提取,但由于噪声的干扰对经验模态分解(EMD)过程和结果影响很大,存在严重的模态混叠现象。针对此不足,提出了首先对原始信号进行归一化相关性甄别和小波包分解预处理技术,对含噪故障信号进行消噪处理后再作HHT分析的改进方法,利用此方法对含静止同步补偿器(STATCOM)的并补线路保护在稳态运行时的测量信号进行分析,结果表明改进HHT方法有效地消除了模态混叠现象。并利用此方法对含STATCOM的并补线路保护在各种故障暂态时的电流信号进行Hilbert谱分析,结果表明,含STATCOM的并补线路故障时的Hilbert谱会发生突变,且区内故障和区外故障时有明显差别。根据此特征构成并补线路单端暂态量保护判据,仿真分析表明,该判据不受故障类型、故障位置、过渡电阻、补偿度以及母线电容变化的影响,具有良好的适应性和灵敏性。文中的分析方法及思路对串补线路暂态保护的应用研究具有一定的参考价值。

Hilbert-Huang transform can make an extraction of non-linear non-stationary signal feature.But due to noise＇s interference,the process of empirical mode decomposition（EMD） and the result is seriously affected and it has the phenomenon of mode aliasing.Based on this shortcoming,this paper proposes an improving HHT algorithm.That is,makes correlated normalization and wavelet packet decomposition preconditioning of the original signal to denoise the fault signal,then makes HHT transform.Using this method the measured signal in shunt-compensated lines with static synchronous compensator（STATCOM） in steady state is analyzed,results show that the improved HHT method is effective to eliminate the aliasing mode phenomenon.It used this method to make HHT spectrum analysis in the current signal of lines with STATCOM in transient state of types of fault.Results show that the Hilbert spectrum will be mutated when fault coming in lines with STATCOM and the spectrum will be absolutely different between in-zone and out-zone fault.According to this feature,the single-ended transient protection criterion of shunt-compensation line is proposed.Simulation results show that the criterion is not affected by the type of fault,the fault location,the fault resistance and the change of bus capacitance.It has favorable flexibility and sensitivity.The analysis method of this paper has certain reference value to the applied research of the transient protection of series-compensation line.