小電流接地方式對電力系統故障的影響
發(fā)布時間：2018-09-17 16:47
【摘要】：小電流接地系統是國內外非常流行的一種接地系統。目前常見的小電流系統都是以接地方式的不同而作區(qū)分的,而最常使用的接地方式主要有經電阻接地、經消弧線圈接地以及不接地三種。目前我國的小電流接地系統主要使用于3-66kV的電力系統中。這主要是因為小電流接地系統在遭遇故障的時候仍然能維持一段時間的正常運行,因此被廣泛使用。我國的6~66kV配電網電力系統多屬于小電流接地系統,一般采用中性點不接地或者中性點經消弧線圈接地的工作方式,因其發(fā)生接地故障時,流過接地點的電流小,又稱中性點非有效接地系統。接地故障是指由于導體與地連接或對地絕緣電阻變的小于規(guī)定值而引起的故障。根據電力系統運行部門的故障統計,由于外界因素(如雷擊、大風、鳥類等)的影響,配電網單相接地故障是配電網故障中最常見的,發(fā)生率最高,占整個電氣短路故障的80%以上。當發(fā)生單相接地故障時,由于不能構成低阻抗的短路回路,接地電流很小,故稱為小電流接地系統。它的優(yōu)點在于發(fā)生單相接地故障時多數情況下可以自動熄弧并恢復絕緣。當線路發(fā)生永久性單相金屬接地故障后,三相系統的線電壓仍然是對稱的,大小與相位并不變化,但系統的接地相對地電容被短接,對地電壓都變?yōu)榱�。為防止另一相在接地而引起兩相短路甚至三相電�?因而必須限制一定時間內排除單相故障。本文致力于解決小電流接地系統在遭遇故障的時候減小對電力系統的損害問題。通過深入分析系統發(fā)生故障的原因,從而在源頭上找到避免故障發(fā)生的辦法。為此,計劃進行下述工作:(1)研究中性點接地各種方式的特點。(2)進行小電流單相接地系統的故障分析。(3)電力系統短路故障分類與計算。(4)進行小電流接地系統故障仿真分析。
[Abstract]:Low current grounding system is a very popular grounding system at home and abroad. At present, the common small current systems are differentiated by different grounding modes, and the most commonly used earthing methods are mainly through resistance grounding, arc suppression coil grounding and non-grounding. At present, the small current grounding system in China is mainly used in the power system of 3-66kV. This is mainly due to the low current grounding system can still maintain normal operation for a period of time in the event of failure, so it is widely used. The power system of 6~66kV distribution network in our country mostly belongs to the small current grounding system. Generally, the neutral point is not grounded or the neutral point is grounded by the arc-suppression coil, because the current passing through the connection place is small when the grounding fault occurs. Also called neutral point non-effective grounding system. Grounding fault refers to the fault caused by the connection of conductor to ground or the change of insulation resistance to ground less than the specified value. According to the fault statistics of power system operation department, because of the influence of external factors (such as lightning strike, strong wind, bird and so on), the single-phase grounding fault of distribution network is the most common fault and the highest incidence. It accounts for more than 80% of all electrical short-circuit faults. When a single-phase grounding fault occurs, it is called a small current grounding system because it cannot form a short circuit with low impedance and the grounding current is very small. Its advantage is that it can automatically extinguish the arc and restore the insulation when the single-phase earth fault occurs. After the permanent single-phase metal grounding fault occurs, the line voltage of the three-phase system is still symmetrical, and the magnitude and phase of the system are not changed, but the grounding capacitance of the system is short-connected and the voltage to the ground becomes zero. In order to prevent the other phase from causing two phase short circuit or even three phase circuit in grounding, it is necessary to limit the single phase fault within a certain time. This paper is devoted to solving the problem of reducing the damage to the power system when the small current grounding system is in trouble. Through in-depth analysis of the causes of system failures, to find ways to avoid failures at the source. Therefore, the following works are planned: (1) study the characteristics of neutral grounding modes; (2) carry out fault analysis of single-phase earthing system with small current; (3) classify and calculate short circuit faults of power system; (4) carry out fault simulation analysis of low current grounding system.
【學位授予單位】：湖北工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM862
本文編號：2246528
[Abstract]:Low current grounding system is a very popular grounding system at home and abroad. At present, the common small current systems are differentiated by different grounding modes, and the most commonly used earthing methods are mainly through resistance grounding, arc suppression coil grounding and non-grounding. At present, the small current grounding system in China is mainly used in the power system of 3-66kV. This is mainly due to the low current grounding system can still maintain normal operation for a period of time in the event of failure, so it is widely used. The power system of 6~66kV distribution network in our country mostly belongs to the small current grounding system. Generally, the neutral point is not grounded or the neutral point is grounded by the arc-suppression coil, because the current passing through the connection place is small when the grounding fault occurs. Also called neutral point non-effective grounding system. Grounding fault refers to the fault caused by the connection of conductor to ground or the change of insulation resistance to ground less than the specified value. According to the fault statistics of power system operation department, because of the influence of external factors (such as lightning strike, strong wind, bird and so on), the single-phase grounding fault of distribution network is the most common fault and the highest incidence. It accounts for more than 80% of all electrical short-circuit faults. When a single-phase grounding fault occurs, it is called a small current grounding system because it cannot form a short circuit with low impedance and the grounding current is very small. Its advantage is that it can automatically extinguish the arc and restore the insulation when the single-phase earth fault occurs. After the permanent single-phase metal grounding fault occurs, the line voltage of the three-phase system is still symmetrical, and the magnitude and phase of the system are not changed, but the grounding capacitance of the system is short-connected and the voltage to the ground becomes zero. In order to prevent the other phase from causing two phase short circuit or even three phase circuit in grounding, it is necessary to limit the single phase fault within a certain time. This paper is devoted to solving the problem of reducing the damage to the power system when the small current grounding system is in trouble. Through in-depth analysis of the causes of system failures, to find ways to avoid failures at the source. Therefore, the following works are planned: (1) study the characteristics of neutral grounding modes; (2) carry out fault analysis of single-phase earthing system with small current; (3) classify and calculate short circuit faults of power system; (4) carry out fault simulation analysis of low current grounding system.
【學位授予單位】：湖北工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM862
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