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基于数学形态学的电力系统振荡中故障识别和改进的选相方法 总被引:11,自引:0,他引:11
为了使振荡闭锁装置能在振荡中再故障时开放保护,就必须能区分振荡与故障,且故障相的单相阻抗继电器在振荡时也应能正确测量阻抗。但如何在振荡中快速正确地选出一个故障相进行阻抗测量是距离保护能否有选择性地切除振荡中故障的关键问题。在动模实验中发现:对于振荡中发生的故障,在一定情况下序分量选相元件会误选相。文中利用级联多分辨形态梯度变换(SMMG)提出了一种电力系统振荡中的故障检测和改进的故障选相方案:先利用一个SMMG滤波器对相电流进行处理,构成一个自适应的振荡中故障起动元件;检测到故障或扰动后,对接地故障,如果由现有的序分量选相方法判断出其为落在包含单相和相间2种故障类型的区域,则可利用故障后3个模电流分量的SMMG系数局部模极大值确定其故障相别。用EMTP在一个系统模型上进行了大量的仿真研究,其结果验证了该方案的有效性和易用性,该方法判别灵敏,结果可靠,所提出的算法易于实现,在现有的微机保护装置中可以直接采用。 相似文献
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基于相间故障弧光电压特征的高压线路选相元件 总被引:6,自引:0,他引:6
提出了一种基于相间故障弧光电压特征的高压线路选相新原理,应用于振荡闭锁期间的选相元件.对接地故障,利用零、负序电流相位差进行分区,每个分区包括某相单相接地和另外两相短路接地两种故障.然后根据相间故障弧光电压Ucosψ小于某一定值,而健全相相间电压的余弦值Ucosψ一般比较大的特征,来得到选相结果,解决了目前选相元件在电力系统振荡时可能发生的误选相问题.通过对不对称故障开放条件的改进,大大提高了单相接地故障的选相速度.该选相元件具有很强的耐过渡电阻能力,并且完全不受分支系数和系统运行方式的影响.RTDS试验验证了新选相元件的准确性和有效性. 相似文献
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For maintaining security of distance relays, power swing blocking is necessary to prevent unintended operation under power swings. To be dependable, distance relays must operate whenever a fault occurs. Therefore, detecting faults during power swings is an important issue since the relay should be able to differentiate the fault condition and not be blocked during that time. This paper presents a new method for detecting a symmetrical fault during a power swing, based on extracting components of the current waveform using the Prony method. The merit of the method is demonstrated by simulating different faults during power swing conditions using the Alternate Transients Program version of the Electromagnetic Transients Program. 相似文献
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The main purpose of power swing blocking is to distinguish faults from power swings. However, the faults occur during a power swing should be detected and cleared promptly. This paper proposes an adaptive concentric power swing blocker (PSB) to overcome incapability of traditional concentric PSB in detecting symmetrical fault during power swing. Based on proposed method, two pairs of concentric characteristics are anticipated which the first one is placed in a stationary position (outer of zone3) but the position of the second pair is adjustable. In order to find the position of the second pair of characteristic, Static Phasor Estimation Error (SPEE) of current signal is utilized in this paper. The proposed method detects the abrupt change in SPEE and puts the second pair of characteristic in location of impedance trajectory correspondingly. Second concentric characteristic records travelling time of impedance trajectory between outer and inner zones and compares to threshold value to detect symmetrical fault during power swing. If recorded time is lower than threshold, three-phase fault is detected during power swing. Intensive studies have been performed and the merit of the method is demonstrated by some test signals simulations. 相似文献
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一种自动适应系统运行方式变化的新型突变量选相元件 总被引:1,自引:0,他引:1
针对传统电流突变量和电压突变量选相元件不能同时满足强弱电源系统侧保护要求的缺点,提出一种新的突变量选相原理。该选相元件在电压突变量基础上引入单相电流突变量进行极化,不但能自动适应系统运行方式的变化,尤其在系统正负序阻抗不等导致传统突变量选相元件失效的场合,更能体现出其优越性。值得指出的是,该选相元件对单相短路故障和相间短路(接地)判断均有很高的灵敏度。直流系统电磁暂态仿真结果表明,即使在正负序严重不对称的场合,该元件也具有很好的选择性。当系统参数大范围变化时,该选相判据也能实现正确选相,比传统突变量选相方案具有更高的可靠性。 相似文献
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用模糊集合理论识别电力系统振荡中的短路的研究 总被引:11,自引:3,他引:8
本文通过对电力系统振荡和短路所呈出的不同特征的分析,从故障特征入手,利用模糊集合理论来识别振荡过程中发生的短路,对于振荡中的三相短路的识别,本文提出一种基于振荡中心电压的波形跟踪识别方法,对于振荡中的不对称故障的识别,本文选取模变换中的Clark变换作为数学工具,与对称分子量变换相结合,构造了Iα/Iβ判据,Ia-Iβ与序分量组合判据,文章给出了相应的模糊数学模型,并经大量的仿真试验,获得良好的仿 相似文献
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A power swing may be caused by any sudden change in the configuration or the loading of an electrical network. During a power swing, the impedance locus moves along an impedance circle with possible encroachment into the distance relay zone, which may cause an unnecessary tripping. In order to prevent the distance relay from tripping under such condition, a novel power swing blocking (PSB) scheme is proposed in this paper. The proposed scheme uses an adaptive neuro-fuzzy inference systems (ANFIS) for preventing distance relay from tripping during power swings. The input signals to ANFIS, include the change of positive sequence impedance, positive and negative sequence currents, and power swing center voltage. Extensive tests show that the proposed PSB has two distinct features that are advantageous over existing schemes. The first is that the proposed scheme is able to detect various kinds of power swings thus block distance relays during power swings, even if the power swings are fast or the power swings occur during single pole open conditions. The second distinct feature is that the proposed scheme is able to clear the blocking if faults occur within the relay trip zone during power swings, even if the faults are high resistance faults, or the faults occur at the power swing center, or the faults occur when the power angle is close to 180°. 相似文献
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振荡中故障选相元件的研究 总被引:2,自引:2,他引:0
目前实用的选相元件在系统振荡时可能会误选相,有必要研究能适用于振荡时的选相方案。分析了振荡中再故障时故障回路测量阻抗不变的特征,并在此基础上提出了一种适用于振荡的新型选相元件。该元件结合常规的零、负序故障分量分区和阻抗值比较方法,采用阻抗变化率的判别从可能的故障类型中识别出真正的故障回路,解决了系统振荡时选择性和速动性之间的矛盾。理论分析和EMTP数字仿真计算表明,新的选相方案在性能上较常规选相方案有明显的改善,可以完全克服阻抗法故障识别在振荡中选相的失配问题,并且该方案原理简单,动作可靠,具有很高的工程应用价值。 相似文献
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Out-of-step blocking function in distance relays is required to distinguish between a power swing and a fault. Speedy and reliable detection of symmetrical faults during power swings presents a challenge. This paper introduces wavelet transform to reliably and quickly detect power swings as well as detect any fault during a power swing. The total number of dyadic wavelet levels of voltage/current waveforms and the choice of particular levels for such detection are carefully studied. A logic block based on the wavelet transform is developed. The output of this block is combined with the output of the conventional digital distance relay to achieve desired performance during power swings. This integrated relay is extensively tested on a simulated system using PSCAD/ EMTDCreg software. 相似文献
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全电流与故障分量电流比例差动判据的比较研究 总被引:18,自引:6,他引:18
全面对比分析了全电流比例差动判据和故障分量电流比例差动判据的灵敏性和安全性。确认了故障分量电流差动判据在灵敏性上优于全电流差动判据,并指出全电流判据在某些特殊工况下如系统振荡中发生故障时可能存在长延时的拒动。当外部故障较大,穿越电流造成CT饱和时,故障分量电流差动判据的安全性也优于全电流差动判据。 相似文献
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级联形态梯度变换及其在继电保护中的应用 总被引:12,自引:4,他引:12
介绍了现在应用已较成熟的灰值腐蚀和灰值膨胀运算,由此引出多分辨形态学梯度变换(MMG)的定义;进而在其基础上提出了一种新型的级联多分辨形态梯度变换(SMMG)的概念,SMMG具有很强的奇异信号检测和波形识别能力,作为一种特征提取工具,SMMG能感受并增强信号波形上的微小变化、反映突变的大小.和其它形态学算子一样,它具有SMMG具有表达直观、滤波器设计简单、数据窗短、计算速度快以及变换结果易于识别、对硬件没有过高的要求等优点,因此在继电保护的信号处理中具有良好的应用潜力和实用价值,在现有的微机保护装置中可以直接采用.文中最后给出了其在电力系统继电保护中应用的2个实例,EMTP仿真研究表明:文中提出的相继速动判据具有更高的灵敏度;所提出的基于SMMG的微机线路保护的选相元件能在8ms内正确地识别几乎所有故障情况的故障相别.由SMMG构成的保护元件灵敏度很高,在电力系统高速及超高速保护方面有良好的应用前景及较大的实用价值. 相似文献
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一种新型振荡中故障选相元件 总被引:1,自引:0,他引:1
振荡中故障准确选相是有选择切除故障和确保距离保护正确动作的前提。在分析现有振荡中选相元件需开放条件配合,导致出口延迟,且易出现误选,进而导致距离保护误动的基础上,提出了一种新型选相元件,此元件首先利用零、负序故障分量进行故障分区,在分区的基础上改变目前采用阻抗确定故障相的做法,而采用Clark变换,分别通过α,β模量信息进行故障选相。此选相方法充分发挥了零、负序故障分量以及模量变化在振荡期间不涉及相量偏移带来计算误差等优势,有效避免了阻抗选相在振荡中的弊端。文中给出了基于RTDS动模仿真数据的测试结果,理论和测试表明:此方法在振荡期间能够可靠、快速、准确地区分故障类型。 相似文献
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The paper presents a data-mining model based adaptive protection scheme enhancing distance relay performance during power swing for both compensated and uncompensated power transmission networks. In the power transmission network, the distance relays are sensitive to certain system event such as power swings, which drive the apparent impedance trajectories into the protection zones of the distance relay (zone-3) causing mal-operation of the distance relay, leading to subsequent blackouts. Further, three-phase balanced symmetrical fault detection during power swing is one of the serious concerns for the distance relay operation. This paper proposed a new adaptive protection scheme method based on data-mining models such as DT (decision tree) and RF (random forests) for providing supervisory control to the operation of the conventional distance relays. The proposed scheme is able to distinguish power swings and faults during power swing including fault zone identification for series compensated power transmission network during stress condition like power swing. The proposed scheme has been validated on a 39-bus New England system which is developed on Dig-Silent power factory commercial software (PF4C) platform and the performance indicate that the proposed scheme can reliably enhance the distance relay operation during power swing. 相似文献
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电力系统高压输电线路非全相运行时,由于不对称开放元件退出,若此时再发生故障,如果仅依靠振荡中心电压持续低的长延时判据来开放振荡闭锁,则影响距离保护的动作速度。该方案不适用于单相接地故障。提出了一种采用零负序电流选相分区结果改变开放单相故障和健全相振荡中心电压突变检测开放相间故障相结合的方案,来解决非全相振荡再故障现有开放元件动作速度慢的缺陷。仿真结果证明了该方案的有效性。 相似文献
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The combined effects of a high impedance ground fault condition and a fast power swing condition cause the apparent impedance `seen' by power system distance protection schemes to vary over a wide range. Previous research work has shown that the detection and location of high impedance faults during power swings is very difficult. A new principle for high impedance fault detection during fast power swings is presented which overcomes these deficiencies. This method forms a part of a complete power swing relaying scheme and can be implemented on standard relaying hardware. Results are presented based on extensive simulation studies carried out on a typical 400 kV transmission system, using the Electromagnetic Transient program (EMTP) 相似文献