【作者】 吴大立；

【导师】 尹项根； 张哲；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2008， 博士

【摘要】 输电线路的继电保护水平对于维护电力系统的安全稳定运行,提高经济效益有着至关重要的意义。而随着我国互联大电网规模的不断扩大与发展,系统容量越来越大,电压等级越来越高,电容电流及TA饱和问题日益突出,保护动作速度却更快的要求,输电线路保护可靠性与安全性的矛盾进一步加剧。因此,研究与改善输电线路保护原理与性能以适应新形式下电力系统的发展尤为迫切。为此,本论文主要围绕电容电流补偿、TA饱和及提高保护动作速度等现代大电网中输电线路保护应用时的难点问题展开相关理论及技术研究,极具现实意义及工程价值。提出了输电线路复合差动保护新方案,有效解决了相量差动保护易受TA饱和的影响,而采样值差动保护灵敏度稍显不足的问题。复合差动保护方案依靠采样值差动原理在1个工频周期内可靠切除大多数较严重的故障,通过相量差动保护原理对轻微内部故障作出反应,同时引入制动电流判据,在严重外部故障时自适应增加200ms延时来克服电流互感器(TA)饱和对相量差动的影响。该方案无需配置复杂的TA饱和检测元件,保护判据成熟可靠。仿真及试验结果表明,该方案的可靠性、灵敏性以及抗TA饱和性能均优于单一原理的差动保护。提出了在输电线路贝瑞隆模型的基础上构造采样值差动保护的新方法。基于相量的电容电流补偿方法无法适用于采样值差动,而基于贝瑞隆模型的采样值差动保护不仅在原理上从时域完全消除了电容电流的影啊,并同样具有传统采样值差动动作速度快、抗TA饱和能力强的特点,较好地解决了采样值差动这一性能优良的保护原理应用于超高压输电长线时的关键技术难题。提出了相位自适应差动保护的新原理,在不影响内部故障灵敏度的情况下,大大提高了差动保护的安全性。TA饱和是一直困扰相量差动保护的难点问题。利用电流相位比电流幅值相对受TA饱和影响较小的特点,引入自适应技术,根据电流的相位信息来自适应调整相量差动保护中的制动系数。内部故障时两侧电流相位差小,则制动系数小,保护灵敏度高。外部故障时两侧电流相位差大,则制动系数相应增大,相位自适应差动保护的抗TA饱和能力得到了显著的提高。提出了基于“阻抗收敛”的反时限距离保护新方法,该方法根据实时测量阻抗收敛的情况自适应选择保护算法的数据窗长,测量阻抗收敛越快,保护算法的数据窗长越短,保护动作越快。进一步与“阶梯型”反时限距离保护配合构成的自适应变数据窗距离保护方案性能更佳,在整个距离I段保护范围内的动作速度都得到了明显改善。论文对高性能成套高压线路保护装置的研制展开了实用化研究,系统阐述了了保护方案的整体配置、硬件结构设计、软件结构设计等重要技术环节。并提出了基于IEEEC37.94标准的实用采样时刻调整法,有效解决了光纤纵联差动保护中的双端数据同步的关键技术问题。动模试验结果表明,保护性能满足设计要求,达到了预期设计目标。论文的最后,对全文进行了系统总结,并指出了下一步需要进行的工作。更多还原

【Abstract】 Relay protection for transmission line is very significance for maintaining safe stabilize work of power system and increasing economic benefits. With the expand and development of interconnected huge electric power grid in China, power system capability is more and more large and electric voltage level is more and more high, which causing the problems of distributed capacitance current and current transformer saturation, thus the contradiction between relay dependability and relay security is further aggravated. Obviously, it is quite urgent to study and improve relay protection criterion and performance to meet the demand of power system development. Thus, the study work is valuable and important in theory and application to solve several difficult problems of transmission line protection applied in large scale power grid such as capacitance current compensation, current transformer saturation and trip speed and so on.Transmission line multi differential protection new scheme is proposed according to shortcomings of single principle such as phasor value based differential protection and sampled value based differential protection. In the proposed scheme, the sampled value based differential protection is used to clean most comparative serious internal faults in one cycle reliably and the slight internal fault can be detected by phasor value based differential protection; at the same time, a restraint current criterion is led into the proposed protection to overcome the impact of current transformer saturation on phasor value based differential protection by means of adaptively inserting the time-delay of 200ms while serious external fault occur. As for the proposed protection scheme, its protective criteria are ripe and reliable, and it is not necessary to configure complex detecting element for current transformer saturation. Simulation results show that the reliability, sensitivity trip speed and immunity to current transformer saturation are better than those of the single principle based differential protections.The new method of transmission line Bergeron model based sampled value differential protection is proposed to solve the problem that phasor based capacitance current compensation methods are not suitable for sampled value differential protection. The proposed method can not only compensate capacitance current in time domain completely, but also inherits the merits of traditional sampled value differential protection such as fast trip speed and well immunity ability to current transformer saturation, the vital technology puzzle of high performance sampled value differential protection applied in high voltage long transmission line is solved well.The new principle of phase angle based self adaptive differential protection is proposed, which increases largely the security of differential protection and not influent the sensitiveness to interal fault. The proposed principle uses the fact that current phase angle error caused by current transformer saturation is smaller than current amplitude, and the self adaptive technology is introduced that the restraint coefficient of differential protection is adjust with current phase angle. When internal fault occurs, the phase angle difference of two end currents is small and the restraint coefficient is small, so the sensitiveness of relay is high. On the contrary, when external fault occurs, the phase angle difference of two end currents is large and the restraint coefficient is large, so the immunity ability to current transformer saturation of the proposed principle is increased significantly.The new method of measured impedance convergence based inverse time distance protection is proposed, which decides data window length according to real-time measured impedance convergence result. The convergence speed of measured impedance is faster, the data window length of protective algorithm is shorter and the trip speed is faster. Especially, the comprehensive self adaptive variable data window distance protection has better performance to improve trip speed of the first zone of distance protection, which composes measured impedance convergence based inverse time distance protection with step mode based inverse time distance protection.The dissertation represents the some importance technology such as protection configuration, hardware architecture and software design and so on during developing high performance complete set of protection device for high voltage transmission line. The IEEE C37.94 standard based sampled time adjust method is proposed to solve efficiently data synchronize of optical fibre based differential protection. The dynamic simulation experiment results show that protective performance can meet the design necessity and agree with prospective design goal.At last, the dissertation gives the systematical summarize and points out the further work.更多还原