本文選題：中性點(diǎn)接地方式　切入點(diǎn)：可靠性概率模型　出處：《重慶大學(xué)》2014年碩士論文

【摘要】：近年來，中壓配電網(wǎng)飛速發(fā)展，電纜覆蓋率大幅增長(zhǎng)、網(wǎng)架結(jié)構(gòu)不斷增強(qiáng)、自動(dòng)化程度日益提高、新能源廣泛接入、新型故障選線技術(shù)的研發(fā)應(yīng)用等，導(dǎo)致了中壓配電網(wǎng)的中性點(diǎn)接地方式多樣化，如何因地制宜的選取中性點(diǎn)接地方式對(duì)中壓配電網(wǎng)的安全穩(wěn)定運(yùn)行具有重要意義。中壓配電網(wǎng)中性點(diǎn)接地方式與供電可靠性、繼電保護(hù)、過電壓防護(hù)、通訊干擾及電氣安全等密切相關(guān)，其選取方法應(yīng)綜合考慮上述因素，以保障人身、設(shè)備安全以及系統(tǒng)運(yùn)行的可靠性和穩(wěn)定性。 本文通過對(duì)比了國(guó)內(nèi)外中壓配電網(wǎng)中性點(diǎn)接地方式的運(yùn)用現(xiàn)狀，分析了不同中性點(diǎn)接地方式下的單相接地短路故障特性，建立了相應(yīng)模型計(jì)算不同條件下的故障電流、工頻過電壓及間歇性電弧接地過電壓，得出了各中性點(diǎn)接地方式下故障電流及過電壓的差異取決于單相接地故障時(shí)不同中性點(diǎn)接地方式對(duì)零序網(wǎng)絡(luò)中零序阻抗的貢獻(xiàn)。此外，對(duì)不同中性點(diǎn)接地方式下的安全防護(hù)措施及關(guān)鍵性問題進(jìn)行了研究，提出了一種保證零序電流保護(hù)靈敏、可靠動(dòng)作，過電壓不超過一定范圍以及最大故障電流在安全規(guī)范要求以內(nèi)的多因素中性點(diǎn)電阻值選取方法；分析了影響消弧線圈接地系統(tǒng)選線準(zhǔn)確率的因素以及各種選線方法的優(yōu)缺點(diǎn)。 建立了中壓配電網(wǎng)不同中性點(diǎn)接地方式下線路的可靠性概率模型，對(duì)比分析計(jì)及、不計(jì)選線不準(zhǔn)確率對(duì)概率模型的影響，以輻射型網(wǎng)絡(luò)為例，評(píng)估了各中性點(diǎn)接地方式下、不同電纜比例時(shí)的配電網(wǎng)可靠性水平。基于上述可靠性評(píng)價(jià)結(jié)果，提出了一種綜合可靠性、安全性及經(jīng)濟(jì)性因素的中壓配電網(wǎng)中性點(diǎn)接地方式?jīng)Q策方法。該方法將不同中性點(diǎn)接地方式下配電網(wǎng)的可靠性評(píng)價(jià)與安全性防護(hù)及建設(shè)運(yùn)行成本相結(jié)合，通過全壽命周期成本最優(yōu)或可靠性水平最高為備選條件來實(shí)現(xiàn)中性點(diǎn)接地方式的決策，并通過算例結(jié)果驗(yàn)證了該決策方法的可行性及有效性，為中壓配電網(wǎng)中性點(diǎn)接地方式的選擇提供了決策依據(jù)。 對(duì)含分布式電源(DG Distributed Generation)的新型中壓配電網(wǎng)，針對(duì)單臺(tái)DG及多臺(tái)DG接入的情況分別建立等值模型，分析了DG并網(wǎng)變壓器接地方式、接入容量及位置不同時(shí)，對(duì)配電網(wǎng)各中性點(diǎn)接地方式在發(fā)生單相接地故障時(shí)零序電流保護(hù)的影響，，并通過仿真計(jì)算及分析，尋求DG并網(wǎng)變壓器與配電網(wǎng)主變中性點(diǎn)接地方式的配合原則。
[Abstract]:In recent years, with the rapid development of the medium voltage distribution network, the cable coverage has increased dramatically, the network structure has been continuously enhanced, the degree of automation has been increasingly improved, new energy sources have been widely connected, new fault line selection technology has been developed and applied, etc.It leads to the diversification of neutral grounding mode in medium voltage distribution network. How to select neutral grounding mode according to local conditions is of great significance to the safe and stable operation of medium voltage distribution network.The neutral grounding mode of medium voltage distribution network is closely related to the reliability of power supply, relay protection, over-voltage protection, communication interference and electrical safety.Equipment safety and system operation reliability and stability.In this paper, the current situation of neutral grounding in medium voltage distribution network at home and abroad is compared, and the characteristics of single-phase earthing short circuit fault under different neutral grounding modes are analyzed, and the corresponding models are established to calculate the fault current under different conditions.The power frequency overvoltage and intermittent arc grounding overvoltage are obtained. It is concluded that the difference of fault current and overvoltage depends on the contribution of different neutral grounding modes to zero-sequence impedance in zero-sequence network.In addition, the safety protection measures and key problems under different neutral grounding modes are studied, and a new method to ensure the sensitive and reliable operation of zero-sequence current protection is proposed.The methods of selecting the resistance value of multi-factor neutral point within a certain range of overvoltage and the maximum fault current within the requirements of safety specification are analyzed, and the factors affecting the accuracy of line selection of arc-suppression coil grounding system are analyzed, as well as the advantages and disadvantages of various methods of line selection.The reliability probability model of middle voltage distribution network with different neutral grounding modes is established. The influence of different neutral grounding modes on the probabilistic model without considering the accuracy of line selection is compared and analyzed. Taking the radiation network as an example, the neutral grounding modes are evaluated.Reliability level of distribution network with different cable ratio.Based on the above reliability evaluation results, a decision method for neutral grounding mode of medium voltage distribution network is proposed, which integrates reliability, safety and economic factors.This method combines the reliability evaluation of distribution network with safety protection and construction operation cost under different neutral grounding modes.The decision of neutral grounding mode is realized by the optimal life cycle cost or the highest reliability level, and the feasibility and effectiveness of the decision method are verified by an example.It provides a decision basis for the selection of neutral grounding mode in medium voltage distribution network.For a new type of medium voltage distribution network with DG Distributed generation (DG Distributed generation), the equivalent models of single DG and multiple DG connections are established, and the grounding mode of DG grid-connected transformers, the different access capacity and location are analyzed.The effect of neutral grounding mode on zero-sequence current protection in single-phase grounding fault in distribution network is discussed. Through simulation calculation and analysis, the coordination principle between DG grid-connected transformer and neutral grounding mode of main transformer in distribution network is sought.
【學(xué)位授予單位】：重慶大學(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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