利用暫態(tài)信息的小電流接地故障選線方法研究
發(fā)布時(shí)間：2018-11-19 10:57
【摘要】：非有效接地電網(wǎng)允許系統(tǒng)帶單相接地故障繼續(xù)運(yùn)行1-2小時(shí),對(duì)供電可靠性的提高十分有利,因此我國及很多國家的中壓配電網(wǎng)廣泛采用非有效接地運(yùn)行方式。當(dāng)配電網(wǎng)發(fā)生單相接地故障時(shí),故障饋線的電流突變量很微弱,對(duì)于電容電流較大的電網(wǎng)又需要利用消弧線圈補(bǔ)償接地電容電流,多種因素嚴(yán)重影響小電流接地故障選線保護(hù)的選擇性和靈敏性。經(jīng)過多年努力,國內(nèi)外專家在小電流接地故障選線技術(shù)方面取得了一定的成績。按照利用信號(hào)的不同,小電流接地選線保護(hù)可分為主動(dòng)式選線保護(hù)和被動(dòng)式選線保護(hù)。主動(dòng)式選線保護(hù)需要增加額外的設(shè)備,經(jīng)濟(jì)性差。被動(dòng)式選線保護(hù)分為利用故障穩(wěn)態(tài)信息保護(hù)和利用故障暫態(tài)信息保護(hù)兩類。對(duì)于諧振接地系統(tǒng),穩(wěn)態(tài)量保護(hù)并不適用。由于故障瞬間暫態(tài)故障分量遠(yuǎn)大于穩(wěn)態(tài)故障分量,受諧振接地運(yùn)行方式的影響小,因此利用故障暫態(tài)信息保護(hù)的靈敏度較高。本文對(duì)故障后的暫態(tài)信息加以利用而提出兩種新的選線方法。 針對(duì)小電流接地故障選線理論分析的缺失,本文基于相模變換理論,透過故障的表面現(xiàn)象看本質(zhì),建立了用于分析故障暫態(tài)分量特征的簡化模型,列出高階電路動(dòng)態(tài)方程,分析了故障電流的暫態(tài)成分,詳細(xì)研究了非有效接地電網(wǎng)發(fā)生單相接地故障時(shí)的電流振蕩機(jī)理。最終,通過對(duì)故障暫態(tài)信號(hào)特征的分析,從本質(zhì)上揭示了非有效接地電網(wǎng)發(fā)生單相接地故障的暫態(tài)特征規(guī)律。 本文介紹了小波變換的基本原理,具有良好時(shí)頻分析特性的小波變換是處理暫態(tài)非平穩(wěn)信號(hào)的理想數(shù)學(xué)工具。通過對(duì)信號(hào)作小波變換的方法來獲取暫態(tài)分量,本文基于零模電流和零模電壓的小波變換模極大值,定義了暫態(tài)幅值和暫態(tài)極性故障測(cè)度。提出了兩種新的小電流接地故障選線方法：基于小波變換的暫態(tài)幅值和暫態(tài)極性故障測(cè)度法。幅值法利用故障饋線零模電流小波變換模極大值的幅值遠(yuǎn)遠(yuǎn)大于非故障饋線進(jìn)行選線;極性法利用故障饋線與非故障饋線零模電流小波變換模極大值的極性相反進(jìn)行選線。 最后,本文建立了非有效接地電網(wǎng)的ATP仿真模型。針對(duì)中性點(diǎn)不接地電網(wǎng)和諧振接地電網(wǎng),改變故障點(diǎn)位置、過渡電阻和故障初相角三種主要影響因素,模擬了單相接地故障,計(jì)算出各饋線的暫態(tài)幅值和暫態(tài)極性故障測(cè)度,通過比較其大小來確定故障饋線,從而驗(yàn)證選線方法的正確性。
[Abstract]:The non-effective grounding network allows the system to continue to run for 1-2 hours with single-phase grounding fault, which is very beneficial to the improvement of power supply reliability. Therefore, the non-effective grounding operation mode is widely used in the medium-voltage distribution network of our country and many countries. When the single-phase grounding fault occurs in the distribution network, the sudden change of the fault feeder current is very weak, and the arc-suppression coil is needed to compensate the grounding capacitance current for the power network with large capacitance current. Many factors seriously affect the selectivity and sensitivity of low current grounding fault line selection protection. After years of efforts, domestic and foreign experts in small current grounding fault line selection technology has made certain achievements. According to the difference of using signal, the low current grounding line selection protection can be divided into active line selection protection and passive line selection protection. Active line selection protection requires additional equipment and low economy. Passive line selection protection can be divided into two categories: using fault steady-state information protection and using fault transient information protection. For resonant grounding system, steady-state protection is not applicable. Because the transient fault component is much larger than the steady-state fault component and is less affected by the resonant grounding operation mode, the fault transient information protection is highly sensitive. In this paper, two new methods of line selection are proposed by using transient information after fault. In this paper, based on the theory of phase mode transformation, a simplified model is established to analyze the characteristics of fault transient components, and the dynamic equations of high-order circuits are listed, which is based on the theory of phase mode transformation and the essence of the surface phenomenon of the fault, aiming at the lack of theoretical analysis of the fault line selection for small current grounding faults. The transient components of fault current are analyzed, and the mechanism of current oscillation is studied in detail. Finally, by analyzing the characteristics of fault transient signals, the law of transient characteristics of single-phase grounding faults in non-effective grounding power network is revealed in essence. The basic principle of wavelet transform is introduced in this paper. Wavelet transform with good time-frequency analysis is an ideal mathematical tool for processing transient non-stationary signals. The transient components are obtained by wavelet transform. Based on the wavelet transform modulus maximum of zero-mode current and zero-mode voltage, the transient amplitude and the measure of transient polarity fault are defined in this paper. In this paper, two new methods of fault line selection for small current grounding are proposed: transient amplitude based on wavelet transform and fault measurement method of transient polarity. The amplitude method makes use of the amplitude of zero mode current wavelet transform modulus maximum of fault feeder line to select line, and polarity method uses the polarity of fault feeder line and non-fault feed line zero mode current wavelet transform modulus maximum to select line. Finally, the ATP simulation model of non-effective grounding power network is established in this paper. For neutral ungrounded power network and resonant grounding power network, three main influencing factors such as changing fault point position, transition resistance and fault initial phase angle, the single-phase grounding fault is simulated, and the transient amplitude and transient polarity fault measure of each feeder are calculated. The fault feeder is determined by comparing its size to verify the correctness of the line selection method.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM862
本文編號(hào)：2342094
[Abstract]:The non-effective grounding network allows the system to continue to run for 1-2 hours with single-phase grounding fault, which is very beneficial to the improvement of power supply reliability. Therefore, the non-effective grounding operation mode is widely used in the medium-voltage distribution network of our country and many countries. When the single-phase grounding fault occurs in the distribution network, the sudden change of the fault feeder current is very weak, and the arc-suppression coil is needed to compensate the grounding capacitance current for the power network with large capacitance current. Many factors seriously affect the selectivity and sensitivity of low current grounding fault line selection protection. After years of efforts, domestic and foreign experts in small current grounding fault line selection technology has made certain achievements. According to the difference of using signal, the low current grounding line selection protection can be divided into active line selection protection and passive line selection protection. Active line selection protection requires additional equipment and low economy. Passive line selection protection can be divided into two categories: using fault steady-state information protection and using fault transient information protection. For resonant grounding system, steady-state protection is not applicable. Because the transient fault component is much larger than the steady-state fault component and is less affected by the resonant grounding operation mode, the fault transient information protection is highly sensitive. In this paper, two new methods of line selection are proposed by using transient information after fault. In this paper, based on the theory of phase mode transformation, a simplified model is established to analyze the characteristics of fault transient components, and the dynamic equations of high-order circuits are listed, which is based on the theory of phase mode transformation and the essence of the surface phenomenon of the fault, aiming at the lack of theoretical analysis of the fault line selection for small current grounding faults. The transient components of fault current are analyzed, and the mechanism of current oscillation is studied in detail. Finally, by analyzing the characteristics of fault transient signals, the law of transient characteristics of single-phase grounding faults in non-effective grounding power network is revealed in essence. The basic principle of wavelet transform is introduced in this paper. Wavelet transform with good time-frequency analysis is an ideal mathematical tool for processing transient non-stationary signals. The transient components are obtained by wavelet transform. Based on the wavelet transform modulus maximum of zero-mode current and zero-mode voltage, the transient amplitude and the measure of transient polarity fault are defined in this paper. In this paper, two new methods of fault line selection for small current grounding are proposed: transient amplitude based on wavelet transform and fault measurement method of transient polarity. The amplitude method makes use of the amplitude of zero mode current wavelet transform modulus maximum of fault feeder line to select line, and polarity method uses the polarity of fault feeder line and non-fault feed line zero mode current wavelet transform modulus maximum to select line. Finally, the ATP simulation model of non-effective grounding power network is established in this paper. For neutral ungrounded power network and resonant grounding power network, three main influencing factors such as changing fault point position, transition resistance and fault initial phase angle, the single-phase grounding fault is simulated, and the transient amplitude and transient polarity fault measure of each feeder are calculated. The fault feeder is determined by comparing its size to verify the correctness of the line selection method.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM862
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