【摘要】：隨著配網(wǎng)不接地系統(tǒng)中電纜線路的廣泛使用,系統(tǒng)電容電流越來越大,傳統(tǒng)的消弧線圈面臨容量不夠、消弧效果差等問題,為此一種開關(guān)式消弧裝置在10 kV系統(tǒng)中逐漸開始推廣使用。然而現(xiàn)場(chǎng)發(fā)現(xiàn)傳統(tǒng)配置下的電壓互感器在該裝置動(dòng)作過程中頻繁發(fā)生過流燒保險(xiǎn)現(xiàn)象,嚴(yán)重威脅電力系統(tǒng)的穩(wěn)定運(yùn)行。因此本文通過電磁暫態(tài)計(jì)算和高電壓模擬試驗(yàn),明確了開關(guān)式消弧下PT熔斷的機(jī)理和最優(yōu)的抑制措施,對(duì)于該裝置接入配網(wǎng)后的安全、可靠運(yùn)行具有重要的理論和工程指導(dǎo)價(jià)值。本文結(jié)合實(shí)際開關(guān)式消弧裝置的結(jié)構(gòu),分析了開關(guān)式消弧的動(dòng)作機(jī)制,闡述了開關(guān)式消弧過程中通過主動(dòng)的單相接地與切除動(dòng)作,從而激發(fā)鐵磁諧振、低頻非線性振蕩的機(jī)理;從理論上分析了兩種暫態(tài)過程的特點(diǎn),并總結(jié)了常見的抑制措施與相應(yīng)優(yōu)缺點(diǎn)�；趯�(shí)際變電站的設(shè)備參數(shù),針對(duì)國(guó)內(nèi)文獻(xiàn)在PT仿真中普遍忽略磁滯和渦流損耗的問題,采用考慮磁滯渦損與深度飽和勵(lì)磁特性的單相PT改進(jìn)模型,并基于分段線性化與逐點(diǎn)遞推法求解了模型的勵(lì)磁曲線;針對(duì)一體式的抗諧振4PT結(jié)構(gòu),基于其磁路特征建立了適用于仿真的簡(jiǎn)化電路模型,通過正序和零序試驗(yàn)確定了模型的正序、零序參數(shù)。考慮到線路對(duì)地電容值越來越大,仿真分析了分頻諧振和低頻非線性振蕩下PT 一次電流的特性,確定了引發(fā)PT保險(xiǎn)熔斷的主要原因是低頻非線性振蕩,并且其影響因素主要有系統(tǒng)電容值與零序阻尼。本文還搭建了 10kV中性點(diǎn)不接地系統(tǒng)模擬試驗(yàn)平臺(tái),在不同的系統(tǒng)電容電流下對(duì)三類典型單相PT進(jìn)行了單相接地與切除的試驗(yàn),并將試驗(yàn)結(jié)果與仿真結(jié)果比較,驗(yàn)證了仿真模型的準(zhǔn)確性。試驗(yàn)中發(fā)現(xiàn)即使遠(yuǎn)離Peterson諧振區(qū)域,單相接地消失仍會(huì)激發(fā)分頻諧振,產(chǎn)生的半波脈沖電流幅值很高,容易導(dǎo)致PT熔斷器熔斷;而在系統(tǒng)參數(shù)合適時(shí),還會(huì)激發(fā)出準(zhǔn)周期諧振,產(chǎn)生的電流幅值同樣很高。對(duì)于常用的改變系統(tǒng)參數(shù)和增大阻尼這兩類消諧措施,結(jié)合仿真、高電壓試驗(yàn)以及現(xiàn)場(chǎng)驗(yàn)證性試驗(yàn)進(jìn)行了消諧、抑制PT過電流效果的比較,分析其優(yōu)缺點(diǎn),最后比較了幾大措施對(duì)零序電壓測(cè)量精度的影響,研究結(jié)果表明采用4PT結(jié)構(gòu)是開關(guān)式消弧接入系統(tǒng)后最優(yōu)的消諧與防PT保險(xiǎn)熔斷措施。
[Abstract]:With the wide use of cable lines in ungrounded distribution systems, the capacitance current of the system becomes larger and larger, and the traditional arc-suppression coil is faced with problems such as insufficient capacity, poor arc suppression effect and so on. For this reason, a switch type arc suppression device is gradually popularized in 10 kV system. However, it is found in the field that the overcurrent burning occurs frequently during the operation of the device, which seriously threatens the stable operation of the power system. Therefore, through electromagnetic transient calculation and high voltage simulation test, the mechanism and optimal suppression measures of PT fuse breakage under switching arc suppression are defined, and the safety of the device after it is connected to the distribution network is discussed. Reliable operation has important theoretical and engineering guiding value. Combined with the structure of the actual switch type arc suppression device, this paper analyzes the action mechanism of the switch type arc suppression, and expounds the mechanism of excitation of ferromagnetic resonance and low frequency nonlinear oscillation through active single-phase grounding and excising action in the process of switching type arc suppression. The characteristics of the two transient processes are analyzed theoretically, and the common suppression measures and their advantages and disadvantages are summarized. Based on the equipment parameters of actual substation, aiming at the problem that hysteresis and eddy current loss are generally ignored in domestic literatures in PT simulation, a single-phase PT improved model considering hysteresis vortex loss and depth saturation excitation characteristics is adopted. The excitation curve of the model is solved based on piecewise linearization and point-by-point recursive method. Based on the magnetic circuit characteristics of the integrated anti-resonant 4PT structure, a simplified circuit model suitable for simulation is established. The positive sequence and zero sequence parameters of the model are determined by positive sequence and zero sequence experiments. Considering the increasing value of the line capacitance to the ground, the characteristics of the primary current of PT under the frequency division resonance and the low frequency nonlinear oscillation are simulated and analyzed, and the main cause of the fuse breaking of the PT is determined to be the low frequency nonlinear oscillation. The main influencing factors are system capacitance and zero sequence damping. In this paper, the simulation test platform of 10kV neutral ungrounded system is also built, and the single-phase grounding and removal of three typical single-phase PT are carried out under different capacitance currents, and the experimental results are compared with the simulation results. The accuracy of the simulation model is verified. It is found that even if far away from the Peterson resonance region, the single-phase grounding will still excite the split-frequency resonance, resulting in a high amplitude of half-wave pulse current, which can easily lead to the fuse of the PT fuse. When the system parameters are suitable, quasi periodic resonance will be excited, and the current amplitude will also be very high. For the two kinds of harmonic elimination measures, such as changing system parameters and increasing damping, harmonic elimination measures are combined with simulation, high voltage test and field verification test. The effects of suppressing PT overcurrent are compared, and their advantages and disadvantages are analyzed. Finally, the effects of several measures on the accuracy of zero-sequence voltage measurement are compared. The results show that the 4PT structure is the best harmonic elimination and anti-PT fusing measures after switching arc-suppression access system.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM732;TM475

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