大型发电机保护关键技术研究

发布时间：2018-05-29 05:10

本文选题：大型发电机 + 继电保护　；参考：《华北电力大学》2014年博士论文

【摘要】：随着互联电网规模的不断扩大,电力系统正向着“大机组、特高压、大电网”方向发展。大机组在绝缘、结构工艺、设计、运行等方面出现了很多新的特点,对发电机保护提出了更多、更高的要求；大电网的远距离、跨区域送电的特点,使得电网结构复杂、运行控制困难,导致电网的安全稳定问题更加突出,机网协调变得更加迫切。而涉网保护,如定/转子接地保护、失磁保护、失步保护等,不完善、可靠性不高,它们在大电网事故中的不正确、不合理动作加剧了电网的崩溃,是发电机保护的固疾、顽疾,也是电网安全稳定的潜在威胁。本文以保障大机组、大电网的安全稳定为目标,针对发电机保护的几个关键技术：定子接地保护、失磁保护、失步保护以及保护配置等展开了深入研究。论文首先分析比较了传统的发电机定子接地保护：基波零序电压保护、三次谐波电压保护的灵敏度及其配合问题。研究表明,大型发电机组的定子对地电容比较大时,这两种保护方案不能满足灵敏度要求,并且不能在发电机静止和启／停机状态下提供保护,需要引入注入式定子接地保护。接着研究分析了注入式定子接地保护的原理、方案设计,以及影响其灵敏度的因素。研究发现发电机接地变压器的参数对保护灵敏度和误差影响很大,并且在工程应用中调试、补偿复杂,难以准确。针对这些问题提出了不受接地变参数影响的新保护方案。新方案将注入与测量回路分开,使保护不受接地变参数的影响,无需补偿就能达到很高的灵敏度,简化了工程调试。动模试验和现场试验也验证了新方案的有效性。研究分析了传统的基于静稳极限阻抗圆特性的失磁保护,分析了它的特点和不足。针对其受发电机负荷变化影响大的缺点,提出自适应负荷变化的新型失磁保护方案。通过仿真证明了新方案的有效性,尤其是在较小负荷下,与传统的静稳极限阻抗圆判据相比,动作更加快速、可靠。研究分析了发电机失磁过程中的阻抗轨迹特征,并提出3种失磁保护新判据。新判据利用了失磁过程中的3个电气量：阻抗轨迹的变化范围、等有功阻抗圆的圆心角、圆心角的变化量。综合3种新判据以及一些辅助措施提出了新失磁保护方案。新方案在失磁后立刻就能检测到,经过短暂延时,躲过可能的非失磁故障造成的扰动,就可以快速发信。经过仿真验证表明,新方案在各种失磁和非失磁工况下都能准确、可靠动作。研究了等能量法和等面积法的发电机失步保护。提出基于实时机械功率测量和等能量法的新型失步保护方案。新失步保护方案能跟踪测量发电机的实时机械功率,使等能量法的失步保护在采取快关汽门等紧急控制手段时更加准确、可靠。研究了扩展等面积法的暂态稳定分析方法,提出一种基于广域测量系统和扩展等面积法的多机失步保护方案。新方案通过广域测量系统获取各发电机的功率、功角数据,利用扩展等面积法判断系统的稳定状态。经仿真验证了保护方案的有效性。最后总结了大型发电机组的特殊性及其对发电机保护提出的新要求,根据大型发电机组的特殊性和现代大电网安全稳定的需要,总结了相关发电机保护的配置原则。
[Abstract]:With the continuous expansion of the scale of the interconnected power grid, the power system is developing in the direction of "large unit, ultra high voltage, large power grid". Large units have many new characteristics in the aspects of insulation, structure technology, design and operation, and put forward more and more demanding for generator protection; the long distance of the large power grid, the characteristics of the transmission across the region, and the electric power The network structure is complicated and the operation control is difficult, which causes the security and stability of the power grid more prominent, and the coordination of the network becomes more urgent. And the network protection, such as the fixed / rotor grounding protection, the loss of magnetic protection, the lost step protection, is not perfect, and the reliability is not high, they are not correct in the large power grid accidents, and the unreasonable action aggravates the breakdown of the power grid and is the generation of power generation. In order to ensure the safety and stability of large power units and large power grids, this paper aims at ensuring the safety and stability of large power units and large power grids. This paper aims at several key technologies of generator protection, such as stator grounding protection, demagnetization protection, lost step protection and protection configuration.
The paper first analyzes and compares the traditional generator stator grounding protection: the fundamental zero sequence voltage protection and the sensitivity and coordination of the three harmonic voltage protection. The study shows that the two protection schemes can not meet the requirements of the sensitivity and can not be stationary and open to the generator when the stator capacitance of the large generator is large. The protection of stator is grounded, and the injection type stator grounding protection is needed.
Then the principle of injection stator grounding protection, the scheme design, and the factors affecting its sensitivity are studied and analyzed. It is found that the parameters of the generator grounding transformer have great influence on the protection sensitivity and error, and the compensation is complex and difficult to be accurate in the engineering application. The new scheme provides a new protection scheme. The new scheme separates the injection from the measurement circuit to make the protection unaffected by the grounding variable parameters. It can achieve high sensitivity without compensation and simplifies the commissioning of the project. The dynamic model test and field test also verify the effectiveness of the new scheme.
This paper studies and analyzes the traditional loss of magnetic protection based on the static stability limit impedance circle characteristics, analyzes its characteristics and shortcomings. In view of its large influence on the change of generator load, a new type of self adaptive load change protection scheme is proposed. The effectiveness of the new scheme is proved by simulation, especially under the small load, with the traditional static. Compared with the steady limit impedance circle criterion, the motion is faster and more reliable.
The characteristics of the impedance track in the process of generator loss are studied and analyzed, and 3 new criteria are proposed. The new criterion uses 3 electrical quantities in the process of demagnetization: the range of the impedance track, the center angle of the active impedance circle, the change of the center angle, and the comprehensive 3 new criteria and some auxiliary measures for the new demagnetization protection. The new scheme can be detected immediately after the loss of magnetic field. After a short delay, the new scheme can quickly send a letter by avoiding the possible disturbance caused by the non loss of magnetic failure. The simulation shows that the new scheme can be accurate and reliable in all kinds of demagnetization and non loss of magnetic conditions.
A new type of lost step protection for generators based on equal energy method and equal area method is studied. A new step protection scheme based on real time mechanical power measurement and equal energy method is proposed. The new lost step protection scheme can track the real time mechanical power of the generator, and make the loss step protection of the equal energy method more accurate when adopting emergency control means such as fast closing the valve and so on. Rely on.
The transient stability analysis method of extended equal area method is studied, and a multi machine lost step protection scheme based on the wide area measurement system and the extended equal area method is proposed. The new scheme obtains the power and power angle data of each generator through the wide area measurement system, and uses the extended equal area method to judge the stability of the system. The protection scheme is verified by simulation. Validity.
At last, the particularity of large generator set and the new requirements for generator protection are summarized. According to the particularity of the large generator set and the need of the safety and stability of the modern large power grid, the principle of the configuration of the related generator protection is summarized.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM307.3

【参考文献】