【作者】 揭林玲；

【导师】 唐昆明；

【作者基本信息】 重庆大学 ， 电气工程， 2009， 硕士

【摘要】 配电线路运行的可靠性、安全性直接影响到广大电力用户。配电线路的保护功能是指故障检测和判断故障区段,并隔离故障区域,恢复正常区域供电。传统继电保护的整定值均通过离线计算获得,在运行中保持不变,保护范围和灵敏度受运行方式影响较大。自适应继电保护是指能根据电力系统运行方式和故障状态的变化而实时改变保护性能、特性或定值的保护,能使保护尽可能地适应电力系统的各种变化,进一步改善保护的性能。本文综述了自适应继电保护的研究现状和发展趋势,在分析了配电线路保护的研究现状与不足的基础上,构建了配电线路的自适应保护方案。提出了一种基于两相相电流差故障分量的自适应电流速断保护。该保护算法能够克服现有自适应速断保护要实时进行故障选相确定故障类型使算法误差增大和复杂化的缺点,本算法不需要确定故障类型系数,并且能根据系统实时运行方式调整保护定值。通过EMTP仿真实例分析结果表明,该方案可使保护在不同运行方式不同故障情况下具有相同的保护范围且大于传统速断保护范围。在确定系统运行方式及计算线路电流电压幅值时,为了有效消除衰减性直流分量及频率波动对自适应保护的参数计算的影响,提出了将离散化的Morlet复小波应用于自适应电流保护的等值参数实时计算中的算法。仿真实例表明,Morlet复小波算法在计算信号的基波幅值上比傅立叶算法具有更好的频率特性和稳定性,计算精度高,且计算工作量增加不大,能够完全满足自适应保护中参数计算的实时性与精确性要求。针对中性点不直接接地的开环运行的环形配电网线路末端故障不能速切的问题,采用一种在无通道条件下不对称故障的自适应保护方案,从故障线路两侧一次性切除故障,保证了保护的选择性与速动性,对于配电网线路末端故障三相对称故障的速切问题也进行了专门的讨论。对线路轻载、单相故障零序电流较小等一些特殊工况也给出了解决方法。针对不同的故障类型、故障位置、负荷容量及不同的过渡电阻进行仿真,结果表明该方案是可行的。更多还原

【Abstract】 Distribution power system is one of the important part of power system and is the closest and most direct link to power consumers. The reliable and safe operation of distribution line will directly affect broad users. Distribution line protection refers to detecting and estimating fault section, separating failure and recovering power supply. Traditional protective relays’settings are gotten off-line and invariable in operating. So they can not get the optimal protecting effect and can not satisfy selectivity, speediness and sensitivity of power system sometimes. Adaptive protection can get its settings on-line on the basis of power system operation mode and fault type. Thus, the protection can adapt to changes of the power system and get the optimal protecting effect.On the basis of summarizing the characteristics of adaptive protection and its development direction and analyzing the present status and disadvantages of line protection, an adaptive protection system is constructed.An adaptive instantaneous trip protection based the phase differential current fault component which need not calculate the ratio of fault type is proposed to solve the problem that fault phase selection making algorithm complex and results inaccurate. The EMTP simulation results show that this protection scheme can get the optimal protecting effect under all kinds of operating mode and can get the same protection range which is larger than traditional protection in different fault type.Real-time calculating system equivalent parameter is one of keys of adaptive current protection. A Morlet complex wavelet based algorithm is presented which is better than general Fourier algorithm in stability and robustness and is unaffected by non-integer harmonics, non-periodic component and fluctuant frequency. The results of simulation show that the complex wavelet algorithm is of high accuracy and can satisfy adaptive protection’s need, so it is highly valuable for engineering practice.An accelerated operation scheme of the non-communication protection technique based on fault components at one end of power lines in distribution system is presented. The new scheme is employed in accelerating the operation of relays, which are in the positions that slow operating time is set when using conventional time grading technique. The solution of special working condition such as light load and low zero sequence current is also considered. The EMTP simulations show that the scheme can increase the response speed of relays in distribution system significantly.更多还原