本文關(guān)鍵詞： “預(yù)調(diào)式”消弧線圈 阻尼電阻 晶閘管 系統(tǒng)對地電容　出處：《山東大學》2016年碩士論文　論文類型：學位論文

【摘要】：在我國,中壓配網(wǎng)廣泛采取中性點非有效接地運行方式。近期,隨著配網(wǎng)范圍的不斷擴大,電網(wǎng)饋線量逐漸增加,線路對地電容電流日益增大,單相接地故障電弧難以自熄,且產(chǎn)生較高的過電壓,可能危害健全相造成兩相短路。因此,具有自動調(diào)諧功能的消弧線圈裝置被廣泛用來補償故障電流以保證配電網(wǎng)運行可靠性。在諧振接地系統(tǒng)中,消弧線圈的存在使得流經(jīng)接地點的電容電流得到了補償,大大提高了供電系統(tǒng)自身運行的可靠性與安全性。而對地電容的準確測量是保證消弧線圈對故障電流進行有效補償?shù)那疤帷１疚脑趯Ω黝愊到y(tǒng)對地電容計算方法進行了歸納總結(jié)的基礎(chǔ)上,針對“預(yù)調(diào)式”消弧線圈提出了一種檢測系統(tǒng)對地電容的新方法,利用投切消弧線圈阻尼電阻的電力電子開關(guān),通過短時控制其導(dǎo)通狀態(tài)以產(chǎn)生含有豐富頻率成分的擾動電壓、電流。利用該擾動電壓、電流信號并結(jié)合基于電力電子擾動技術(shù)的諧波阻抗測量方法測量系統(tǒng)對地電容以用于“預(yù)調(diào)式”消弧線圈的自調(diào)諧。電網(wǎng)正常工作情況下,通過短時改變投切阻尼電阻的晶閘管的導(dǎo)通狀態(tài),等效于將阻尼電阻短時退出工作,進而在晶閘管兩端產(chǎn)生含有豐富頻率成分的擾動電壓、電流信號�；谂潆娋W(wǎng)的近似線性,各頻次下擾動電壓與擾動電流呈現(xiàn)線性關(guān)系。利用擾動電壓、電流信號并結(jié)合基于電力電子擾動技術(shù)的諧波阻抗測量方法計算系統(tǒng)對地電容。本文首先對方案的工作原理進行了闡述,利用故障分析原理和電路理論對電網(wǎng)模型進行等效簡化,利用簡化模型并結(jié)合基于電力電子擾動技術(shù)的諧波阻抗測量方法給出了兩種阻尼電阻接線方式下系統(tǒng)對地電容與擾動信號持續(xù)時間的理論表達式,針對個別頻次下檢測結(jié)果存在誤差的現(xiàn)象,利用最小二乘法對檢測結(jié)果進行優(yōu)化,提高檢測精度。其次,利用仿真手段對方案的可行性進行驗證。通過設(shè)置仿真參數(shù),在不同諧波頻次、晶閘管觸發(fā)角、脫諧度、不平衡度下的諧振接地系統(tǒng)進行仿真分析,測量對地電容,同時研究阻尼電阻短時間退出工作對中性點位移電壓的影響。最后,通過模擬實驗驗證了仿真結(jié)果的正確性,基于模擬實驗的結(jié)果,對晶閘管觸發(fā)角及中性點最小位移電壓的確定給出了指導(dǎo)性建議。本文為系統(tǒng)對地電容的計算提供了一種新的可行方案,對消弧線圈的自動補償具有積極意義。同時,通過本文進一步拓展了電力電子擾動技術(shù)在電力系統(tǒng)中的應(yīng)用。
[Abstract]:In our country, neutral point is widely used in medium voltage distribution network. Recently, with the expansion of distribution network, the number of feeders is increasing gradually, and the capacitance current of line to ground is increasing day by day. Single-phase grounding fault arc is difficult to self-extinguish and produce higher overvoltage, which may harm the sound phase and cause two-phase short circuit. The arc-suppression coil with automatic tuning function is widely used to compensate the fault current to ensure the reliability of the distribution network. The existence of the arc-suppression coil compensates the capacitive current flowing through the junction. The reliability and safety of the power supply system is greatly improved, and the accurate measurement of the earth capacitance is the premise to ensure the effective compensation of the fault current by the arc suppression coil. In this paper, the calculation method of the earth capacitance for all kinds of systems is presented. On the basis of summing up. In this paper, a new method of detecting system to ground capacitance is proposed for "preset" arc-suppression coil. The power electronic switch is used to damp the resistance of arc-suppression coil. A disturbance voltage, current, which contains rich frequency components, is generated by controlling its conduction state for a short period of time.; the disturbance voltage is utilized. The current signal and harmonic impedance measurement method based on power electronic disturbance technique are used to measure the system capacitance to the ground for self-tuning of the "preset" arc suppression coil. By changing the on-on state of the thyristor with damped resistance in a short time, it is equivalent to withdraw the damping resistor from work for a short time, and then generate the disturbance voltage with rich frequency components at the two ends of the thyristor. Current signal. Based on the approximate linearity of the distribution network, the disturbance voltage is linearly related to the disturbance current at each frequency. The current signal and the harmonic impedance measurement method based on power electronic disturbance technology are used to calculate the capacitance of the system. Firstly, the working principle of the scheme is described in this paper. The fault analysis principle and circuit theory are used to simplify the power network model. Based on the simplified model and the harmonic impedance measurement method based on the power electronic disturbance technique, the theoretical expressions of the system ground capacitance and disturbance signal duration under two damping resistance wiring modes are presented. In order to improve the accuracy of detection, the least square method is used to optimize the detection results. Through setting the simulation parameters, the resonant grounding system with different harmonic frequency, thyristor trigger angle, detuning degree and unbalance is simulated and analyzed. Measure the capacitance to the ground and study the influence of the short time withdrawal of damping resistance on the neutral displacement voltage. Finally, the correctness of the simulation results is verified by the simulation experiment, based on the results of the simulation experiment. Some guiding suggestions are given for the determination of the trigger angle and the minimum displacement voltage of the neutral point of the thyristor, and a new feasible scheme for calculating the ground capacitance of the system is provided in this paper. It has positive significance for automatic compensation of arc-suppression coil. At the same time, the application of power electronic disturbance technology in power system is further expanded in this paper.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TM934

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