摘要：配电网在电力系统中起着承上启下的作用，它从输电网接受电能，经过降压变换之后直接分配给工业和民用电力用户。配电网的可靠性直接影响着用户供电的可靠性，配电网的供电效率直接影响着电网的经济性。配电网的故障大多数为不对称故障，不对称故障包括单相接地短路、两相相间短路、两相接地短路、单相断开和两相断开。在三相电路中，对于任意一组不对称的三相向量，可以分解为正序、负序和零序三组三相对称分量之和。将短路点处发生短路的相对地电压为零，而正常相的对地电压由于没有和地相接而不为零。故障点外的其余部分的参数仍是对称的。利用不对称分量法，将发生故障时每组不对称电势源分解为正序、负序和零序三组对称分量。再根据发生故障时产生的边界条件和三序分量的相互关系来确定故障相的复合序网络。62199

毕业论文关键词： 接地；短路；断相；零序 

Fault Analysis and Research in low and medium voltage distribution network

Abstract:Distribution network plays a connecting role in the power system, which receives power from the grid, after a step-down conversion directly allocated to the industrial and residential electricity users.Distribution network reliability directly affects the user power supply reliability, power distribution network directly affects the efficiency of the grid economy.Most of the distribution network fault asymmetric faults, asymmetry faults include single-phase ground short circuit, phase short circuit two-phase, two-phase ground short circuit, single-phase and two-phase disconnect disconnected.In the three-phase circuit, for any set of asymmetrical three-phase vector can be decomposed into positive, negative and zero sequence component of the three-phase and symmetrical.The short-circuit short-circuit at a point opposite voltage is zero, and the ground voltage and the absence of normal phase to ground instead of zero. The rest of the parameters outside of the point of failure is still symmetrical. An asymmetric component method, when a failure occurs each potential source of asymmetric decomposed into positive, negative and zero sequence three sets of symmetrical components. And then to determine the composite sequence network fault with according to the relationship between the boundary conditions and three-sequence component generated when a fault occurs.

KeyWords：Ground；Short circuit；Break phase；Zero-sequence

 目录

1.电力系统的故障及危害 2

2.1对称分量法 3

2.1.1对称分量法的概念 3

2.1.2.电力系统不对称分量的特点 3

2.2.3对称分量法在电力系统不对称故障分析中的应用 4

2.2故障分析的重要性 4

3.中低压配电网短路故障的分析 5

3.1中性点直接接地系统 5

3.11单相接地短路 5

3.1.2两相接地短路 8

3.2中性点不接地系统 11

3.2.1单相接地短路 11

3.2.2两相相间短路 12

3.3.3中性点不接地系统中两相短路接地 15

3.3中性点经消弧线圈接地系统 17

发生单相短路接地 17

4.电力系统断相故障的分析 18