Busbar differential relaying method based on combined amplitude and phase information of high frequency transient currents is put forward in this paper for the speed and reliability problems of busbar protection based...Busbar differential relaying method based on combined amplitude and phase information of high frequency transient currents is put forward in this paper for the speed and reliability problems of busbar protection based on fundamental frequency. Under the analysis of features of bus high frequency differential currents, complex wavelet analysis is used to extract the amplitude and phase features of 1/4 period high frequency differential currents, and amplitude and phase information are used to form the polar coordinates. Bus fault is identified intuitively and precisely according to polar locus differences. This polar coordinates represented busbar differential protection scheme based on high frequency transient signals can not only avoid TA saturation, realizing quick protection, lots of PSCAD/EMTDC simulations also show that this busbar differential protection scheme works well under different fault conditions.展开更多
Neutral beam injection is one of the effective auxiliary heating methods in magnetic-confinementfusion experiments. In order to acquire the suppressor-grid current signal and avoid the grid being damaged by overheatin...Neutral beam injection is one of the effective auxiliary heating methods in magnetic-confinementfusion experiments. In order to acquire the suppressor-grid current signal and avoid the grid being damaged by overheating, a data acquisition and over-current protection system based on the PXI（PCI e Xtensions for Instrumentation） platform has been developed. The system consists of a current sensor, data acquisition module and over-current protection module. In the data acquisition module,the acquired data of one shot will be transferred in isolation and saved in a data-storage server in a txt file. It can also be recalled using NBWave for future analysis. The over-current protection module contains two modes： remote and local. This gives it the function of setting a threshold voltage remotely and locally, and the forbidden time of over-current protection also can be set by a host PC in remote mode. Experimental results demonstrate that the data acquisition and overcurrent protection system has the advantages of setting forbidden time and isolation transmission.展开更多
In the present <span><span style="white-space:nowrap;">scenario</span></span><span></span><span style="font-family:;" "=""><span> the ...In the present <span><span style="white-space:nowrap;">scenario</span></span><span></span><span style="font-family:;" "=""><span> the protection system has become an important issue in the </span><span>field of the power system. An Intelligent protection system has been introduced in many sectors like low voltage DC breakers</span><i><span>,</span></i><span> VCB</span><i><span>,</span></i><span> SF6 </span><span>and</span><span> so on. The said protection schemes have been developed to control the moving contacts using intelligent algorithms for tripping overall load against phase to ground faults occurring within the system. The related works have introduced Trapezoidal and Triangular membership functions as input to the fuzzy inference system. It is also found that the Fuzzy Logic Controller has been designed by taking two inputs as current and voltage. The output membership function has been preferred by implementing Trapezoidal and Gaussian membership functions. In this paper</span><i><span>,</span></i><span> a new concept based </span><span>over current</span><span> protection scheme has been introduced. </span><span>Intelligent</span><span> relaying technique has been used to trip a particular load against over current fault by introducing multistage cascaded intelligent relaying. Initially</span><i><span>,</span></i><span> the proposed method is carried out for Stage-I and reported by incorporating fuzzy algorithm by taking current error and current error rates as input using Gaussian membership function to the black box and fed signal to the breaker as output using trapezoidal and triangular membership function respectively to control the loads connected in the system. The </span><span>best</span></span><span>-</span><span>fit</span><span style="font-family:;" "=""><span> membership function as input to the fuzzy engine is shown here is </span><span>Gaussian</span><span> membership function. The analysis reported here by taking both the fault scenario as </span><span>phase</span><span> to phase and phase to ground respectively.</span></span>展开更多
针对目前柔性直流(voltage source converter-based high voltage DC,VSC-HVDC)电网的线路保护中存在的问题,提出一种基于双端初始电流行波(Initial current traveling wave,ICTW)时频矩阵相似度的柔性直流输电线路保护原理。首先,对柔...针对目前柔性直流(voltage source converter-based high voltage DC,VSC-HVDC)电网的线路保护中存在的问题,提出一种基于双端初始电流行波(Initial current traveling wave,ICTW)时频矩阵相似度的柔性直流输电线路保护原理。首先,对柔性直流电网在线路区内外故障下两端保护所在处ICTW的故障特性进行分析,总结出在特定时间窗内,区内故障下两端ICTW的频域相似度远高于区外故障。在此基础上,利用S变换对双端ICTW进行时频分析,建立时频矩阵,并对其做奇异值分解(singular value decomposition,SVD)。然后根据特征矩阵构造双端ICTW的相似度计算公式,以该相似度的大小判别线路区内外故障。另外,根据线路两端ICTW的高低频能量比识别雷击干扰。最后,各种故障情况下的仿真结果表明,该保护原理不依赖线路边界元件,可以保护不同长度线路的全长,具有更高的耐过渡电阻和抗噪声能力,并且能够满足柔性直流电网主保护的速动性要求。展开更多
文摘Busbar differential relaying method based on combined amplitude and phase information of high frequency transient currents is put forward in this paper for the speed and reliability problems of busbar protection based on fundamental frequency. Under the analysis of features of bus high frequency differential currents, complex wavelet analysis is used to extract the amplitude and phase features of 1/4 period high frequency differential currents, and amplitude and phase information are used to form the polar coordinates. Bus fault is identified intuitively and precisely according to polar locus differences. This polar coordinates represented busbar differential protection scheme based on high frequency transient signals can not only avoid TA saturation, realizing quick protection, lots of PSCAD/EMTDC simulations also show that this busbar differential protection scheme works well under different fault conditions.
基金supported by National Natural Science Foundation of China(No.11575240)Key Program of Research and Development of Hefei Science Center,CAS(grant 2016HSC-KPRD002)
文摘Neutral beam injection is one of the effective auxiliary heating methods in magnetic-confinementfusion experiments. In order to acquire the suppressor-grid current signal and avoid the grid being damaged by overheating, a data acquisition and over-current protection system based on the PXI（PCI e Xtensions for Instrumentation） platform has been developed. The system consists of a current sensor, data acquisition module and over-current protection module. In the data acquisition module,the acquired data of one shot will be transferred in isolation and saved in a data-storage server in a txt file. It can also be recalled using NBWave for future analysis. The over-current protection module contains two modes： remote and local. This gives it the function of setting a threshold voltage remotely and locally, and the forbidden time of over-current protection also can be set by a host PC in remote mode. Experimental results demonstrate that the data acquisition and overcurrent protection system has the advantages of setting forbidden time and isolation transmission.
文摘In the present <span><span style="white-space:nowrap;">scenario</span></span><span></span><span style="font-family:;" "=""><span> the protection system has become an important issue in the </span><span>field of the power system. An Intelligent protection system has been introduced in many sectors like low voltage DC breakers</span><i><span>,</span></i><span> VCB</span><i><span>,</span></i><span> SF6 </span><span>and</span><span> so on. The said protection schemes have been developed to control the moving contacts using intelligent algorithms for tripping overall load against phase to ground faults occurring within the system. The related works have introduced Trapezoidal and Triangular membership functions as input to the fuzzy inference system. It is also found that the Fuzzy Logic Controller has been designed by taking two inputs as current and voltage. The output membership function has been preferred by implementing Trapezoidal and Gaussian membership functions. In this paper</span><i><span>,</span></i><span> a new concept based </span><span>over current</span><span> protection scheme has been introduced. </span><span>Intelligent</span><span> relaying technique has been used to trip a particular load against over current fault by introducing multistage cascaded intelligent relaying. Initially</span><i><span>,</span></i><span> the proposed method is carried out for Stage-I and reported by incorporating fuzzy algorithm by taking current error and current error rates as input using Gaussian membership function to the black box and fed signal to the breaker as output using trapezoidal and triangular membership function respectively to control the loads connected in the system. The </span><span>best</span></span><span>-</span><span>fit</span><span style="font-family:;" "=""><span> membership function as input to the fuzzy engine is shown here is </span><span>Gaussian</span><span> membership function. The analysis reported here by taking both the fault scenario as </span><span>phase</span><span> to phase and phase to ground respectively.</span></span>
文摘针对目前柔性直流(voltage source converter-based high voltage DC,VSC-HVDC)电网的线路保护中存在的问题,提出一种基于双端初始电流行波(Initial current traveling wave,ICTW)时频矩阵相似度的柔性直流输电线路保护原理。首先,对柔性直流电网在线路区内外故障下两端保护所在处ICTW的故障特性进行分析,总结出在特定时间窗内,区内故障下两端ICTW的频域相似度远高于区外故障。在此基础上,利用S变换对双端ICTW进行时频分析,建立时频矩阵,并对其做奇异值分解(singular value decomposition,SVD)。然后根据特征矩阵构造双端ICTW的相似度计算公式,以该相似度的大小判别线路区内外故障。另外,根据线路两端ICTW的高低频能量比识别雷击干扰。最后,各种故障情况下的仿真结果表明,该保护原理不依赖线路边界元件,可以保护不同长度线路的全长,具有更高的耐过渡电阻和抗噪声能力,并且能够满足柔性直流电网主保护的速动性要求。
