【作者】 刘毅；

【导师】 尹项根；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2009， 硕士

【摘要】 近年来,随着我国国民经济不断向前发展,电力需求与日俱增,对电网输电容量提出了更高的要求。随着我国第一条500kV同杆并架双回线路洪龙线的投运,同杆并架双回输电线路因其输送容量大、节约输电走廊等优势在我国被广泛应用。同杆并架双回输电线路线间互感关系复杂、故障种类繁多,以往用于单回线路的主保护和重合闸方案不能满足同杆并架双回输电线路的要求;现有同杆并架双回线路的物理模型均只考虑了线路间零序互感,不能模拟同杆并架双回输电线路各互感间存在的差异,无法真实反映同杆并架双回线路各种故障形式下的电气量特征。因此,对同杆并架双回输电线路相关问题的研究有着重要意义。论文围绕同杆并架双回线路的参数对称性、物理模型构建、分相差动电容电流补偿及自适应重合闸等方面的关键技术展开研究和论述。同杆并架双回输电线路参数对称性对电网的正常运行和保护的正确动作有着重要意义。同杆并架双回线路之间的空间距离很近,不同相序排列模式会影响线路参数的对称性。论文深入分析了现有的三种相序排列模式对常规同杆并架双回线路和紧凑型同杆并架双回线路参数对称性的影响,并据此提出了能满足同杆并架双回输电线路参数对称要求且简单实用的相序排列模式和换位方式。现有双回线路的物理模型都只考虑了线路之间零序互感的影响,难以真实反映同杆并架线路在各种工况和故障状态下的电气量变化特性,论文从同杆并架双回线相与相之间的耦合互感着手,提出了一种构建同杆并架双回输电线路物理模型的新方法,能真实模拟同杆并架双回线各线间互感的差异。论文以某实际同杆并架双回线路为原型,运用该方法构建了物理模型,并通过动态模拟实验和数字仿真验证了该物理模型在各种稳态、暂态情况以及不同工况下其模拟精度均能满足研究和工程应用要求。运行经验和大量仿真结果表明,同杆并架双回线路电容受运行方式和环境的影响很大,因而作为同杆并架双回输电线路主保护的分相电流差动保护为保证其动作性能需要反映这种电容的实时动态变化,而现行的电容电流补偿方案不能满足上述要求。论文在对比分析稳态补偿及暂态补偿方法的基础上,提出了一种电容电流动态补偿新方案。该方案可以克服运行方式和环境变化对同杆并架双回线电容的影响,精确地补偿电容电流,从而降低分相差动保护门槛值,提高保护灵敏度。目前对自适应重合闸的研究主要集中在单回线路单相故障方面,鲜有专门针对同杆并架双回输电线路的。论文在分析电压自适应和相位自适应重合闸判据的基础上,结合同杆并架双回线单相故障和单相跨单相故障时的电气量特征,提出了一种基于相位自适应判据、电压自适应判据及按相序重合闸的组合判据;仿真结果表明该判据可以准确地判别同杆并架双回线路单相故障和单相跨单相故障的故障性质。更多还原

【Abstract】 With the constant development of the national economy, our country’s electric power demand has been growing day by day. Following the first 500kV double transmission lines on the same tower hong-long lines to be in use, the double transmission lines on the same tower has been widely used because of its advantages in transmission capacity and saving transmission corridor. Due to its complex mutual inductance and various fault kinds, double transmission lines on the same tower can’t adopt the main protection and automatic reclosing used on single circuit transmission lines. The physical model of double transmission lines on the same tower being used only considered the zero-sequence mutual inductance, which can’t simulate the difference in double transmission lines on the same tower’s mutual inductance, so that it also can’t actual reflect the characteristics of electrical quantities under different kinds of faults. Therefore, the research for double transmission lines on the same tower is very important and necessary. The work is very valuable in theory and application to solve the problems in double transmission lines on the same tower such as transmission lines’symmetry, physical model, capacitance current compensation and adapt reclosure.For double transmission lines on the same tower , the different phase sequence arrangement mode will affect the transmission lines’symmetry. In this paper, several existing different phase sequence arrangement modes’effects on the symmetry of double transmission lines on the same tower were deeply analyzed. Some suggestions on the phase sequence arrangement and transposition form to ensure the double transmission lines on the same tower’s symmetry were also proposed.To solve the problem that the existing double transmission lines on the same tower’s physical model can’t simulate the difference in mutual inductance, this paper presented a new method for designing the physical model. The new physical model designed by the new method can really simulate the difference between the mutual inductances. An actual segment of double transmission lines on the same tower was taken as prototype , and the physical model was constructed using the new method. Moreover, the physical model’s simulation capacity under various normal and fault conditions was confirmed through dynamic simulation test and digital simulation test.According to the service experience and the massive simulation results, the capacitance of double transmission lines on the same tower was influenced by the operational model and the surroundings. As phase segregated 8 protection was used as the main protection for double transmission lines on the same tower, the general capacitance current compensation can’t meet the actual operational requirements. A new scheme for capacitance current compensation was proposed in the paper basing on the comparatively analysis of the steady compensation and the transient compensation. The new capacitance current compensation method can get over the effects of the operational model and surroundings, and compensate the capacitance current exactly, thereby reduce the threshold of the protection and improve its sensitivity.At present, the researches on adapt reclosure are mainly focused on the single phase fault on the single transmission line, very few researches are specially aimed at the double transmission lines on the same tower. This paper deeply analyzed the voltage adapt reclosure and the phase adapt reclosure, and then presented a new adapt reclosure basing on the characteristics of single phase fault and single phase cross single phase fault in double transmission lines on the same tower . Digital simulation indicated that the new adapt reclosure can judge the fault properties of single phase fault and single phase cross single phase fault in double transmission lines on the same tower exactly.更多还原