zero signal current 中文意思是什麼
zero signal current
解釋
無信號電流-
Firstly, we analyze the transient and steady character of single phase high - impedance grounding fault. secondly, based on wavelet analysis on checking mutational signal and direction high frequency protection theory, utilizing zero sequence current and module current, this paper provides a new scheme including fault starting element, fault phase selection element, directional element and main criterion. this scheme can bear high impedance and is immune to system surge and frequency warp, which gets over the shortcoming of the lack of sensitivity
由於現有的保護方案無法快速有效地切除此類故障，本文在詳細分析了單相高阻接地故障的穩態和暫態特性的基礎上，從小波分析原理出發，利用小波變換檢測突變信號的原理，以零序電流、模電流等為研究對象，結合方向高頻保護的原理，設計了一套包含啟動元件、選相元件、方向元件、主保護的保護新方案。 -
The microprocessor is used to realize digital control as flip plus of the scr. the ic chip sa866ae of mitel company is utilized as the low frequency signal generator of the system. furthermore in the zero - current detection circuit, use the photocoupler gaalas ired and photo ic to detect zero - current, furthest shorten the commutating " died region ", prevent the current from distorting
設計中採用單片機控制可控硅的觸發脈沖，實現數字化控制，並利用mitel公司的三相pwm交流電機脈寬調制晶元sa866ae ，成功研製了交-交頻器中的低頻信號發生器裝置，效果良好；此外利用用光電檢測元件進行系統零電流的檢測，盡可能地縮短換相死區，防止電流發生畸變，成功地解決了原有低頻電源系統中存在的兩大難題。 -
One is to use fourier transformation to convert the source signal from time domain to frequency domain and to discard high frequency harmonious components upwards of 19 ( gb / t14953 - 93 d5. 3 demanding ), then to have static huffman coding to the quantized char array which is composed of reserved direct current component and basic wave and each high frequency " s amplitudes and angles. the other is to use discrete wavelet transformation to convert the source signal from time domain to frequency domain and to set the high frequency coefficients that its absolute value is smaller than the given threshold to zero, then to have dynamic huffman coding to the quantized char array which is composed of multiple, wavelet ' s level, datum length, low frequency coefficients and reserved high frequency coefficients. mass simulinks and analyses under the two circumstances have done to show that data compression ratio is small and the relative error is also small and within the permission of engineering and the compression problem can be solved in theory of measured datum of power system
第一種情況的壓縮方法為：採用傳統的傅立葉變換把原始信號從時間域變換到頻率域，舍棄20次及其以上的高次諧波成分（保證了gb / t14953 ? 93d5 . 3要求） ，然後對保留的直流分量、基波和各次諧波的幅值和相角數據量化后和量化時分別乘以的倍數系數構成一個數組，以字元形式保存，採用靜態huffman編碼對變換數據進行壓縮；採用離散小波變換把原始信號從時間域變換到頻率域，然後對分解得到的高頻系數進行閾值量化處理，對乘以的倍數系數、小波變換的階數、小波變換后的低頻、各級高頻以及原始數據長度、量化后的低頻系數以及保留的高頻系數大小、位置構成一個數組，以字元形式保存，採用動態huffman編碼對這個文件進行壓縮。 -
The working principle of pulsed eddy current ( pec ) nondestructive testing technology is analyzed, the pec testing system was been established to examined the specimen of multi - layered aircraft structure, peak and zero - crossing time of the time domain transient response signal of pec are extracted as the features to detect the corrosion in the second layer of aircraft structure quantificationally, the experiment results are consistent with that of the theory analysis, as the pec have the advantages of fast speed and quantification, this makes the method have the broad using foreground in the testing of aircraft structure corrosion
摘要對脈沖渦流無損檢測技術的工作原理進行了分析，建立了脈沖渦流的檢測系統對加工的模擬飛機多層結構的試件進行了測試，提取其時域瞬態感應信號的峰值和過零時間作為特徵量，對出現在飛機多層結構第二層中的腐蝕缺陷進行了定量檢測，試驗結果和理論分析相一致，證明了脈沖渦流檢測方法的有效性，由於其具有快速和定量化的優點因而在飛機結構的腐蝕檢測中具有廣闊的應用前景。
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