适应智能电网韧性电源需求的大型发电机保护研究

发布时间：2018-05-18 11:44

本文选题：韧性电源 + 大型发电机　；参考：《华中科技大学》2014年博士论文

【摘要】：构筑坚强智能电网离不开强有力的电源支撑,只有打造适应其发展、满足其需求、协调其运行的韧性电源,才能发挥智能电网的优势和效益,否则智能电网只能是“无源之水,无本之木”。大型发电机组作为主力支撑电源,是构建智能电网韧性电源的关键。智能电网中具有间歇性和随机性特征的新能源发电的大规模并网,对大型常规能源机组的支撑作用提出更高要求,同时,新型发电和输配电技术的应用使得机组外部运行环境更加复杂,大型机组的运行安全面临新的挑战。继电保护是大型发电机重要的安全防护措施,构建智能电网的韧性电源需要发电机继电保护在保障机组安全的同时,兼顾电网运行安全,充分发挥大型机组对电网的支撑作用。论文以适应智能电网韧性电源需求为目标,围绕大型发电机中对电网运行有重要影响的继电保护展开研究工作,对智能电网的安全、高效、经济运行具有重大而深远的意义。定子接地是发电机最常见的一种故障,接地电流大小是衡量故障危害程度的直接指标。论文提出一种基于接地电流的大型发电机定子接地保护,故障发生后实时计算接地电流大小,只有当其大于安全允许值时才跳闸停机,否则只发出告警信号,在保障发电机安全的前提下,避免了大型发电机跳闸对电网稳定运行造成的冲击。提出一种发电机定子接地故障定位方法,自动识别出故障相、故障分支和故障线圈,大幅减少了故障排除工作量和停机检修时间。失步振荡是大机组与电网相互作用与协调的重要问题之一。论文提出了一种兼顾机网安全的大型发电机单机失步保护方案,充分发挥了机组承受失步振荡的能力,增强了大型机组在系统振荡时对电网的支撑作用；提出了一种兼顾机网安全的大型发电机多机失步保护动作策略,切除最少的机组使系统恢复同步,避免了多机同时跳闸对电网安全造成的冲击；在此基础上,由多机失步保护和单机失步保护分别构成发电机应对失步振荡的第一道防线和第二道防线。反时限保护是适应智能电网韧性电源需求的大型发电机保护体系中的重要保护。论文分析了现有反时限保护存在的问题,并提出一种基于能力曲线最优拟合的大型发电机反时限保护,实现动作特性曲线与发电机能力曲线的最优匹配,而且其实现算法能够准确反映发电机在异常工况下热量累积的动态过程,在保证机组安全的前提下充分发挥了机组的效益,符合智能电网对电源的韧性需求。单元件横差保护是大型发电机反应匝间短路的重要主保护,其主要难题是在保证外部故障不误动的同时提高反应内部小匝差短路的灵敏度。论文研究了单元件横差不平衡电流的产生机理、影响因素,分析了现有单元件横差保护在原理、应用等方面存在的问题。在此基础上,提出了一种基于气隙电动势制动的单元件横差保护判据,与现有保护判据配合使用,可在保证外部故障不误动的同时,扩大对内部匝间短路的覆盖范围,增强了大型发电机的安全防御以及对电网运行的支撑作用。失磁保护是发电机重要的涉网保护,论文围绕大型发电机失磁保护与电网协调的两个关键问题展开研究：针对目前转子侧判据不够稳定可靠的问题,提出一种基于空载电动势的辅助判据,并给出了发电机空载电动势的计算方法和带有该辅助判据的失磁保护总体方案,提高了失磁保护在电网振荡和故障时的可靠性；针对目前失磁保护与低励限制缺少配合的问题,研究了二者之间的配合方法、原则以及步骤,在保障安全的前提下充分发挥机组的进相运行能力,同时避免失磁保护抢先低励限制动作给电网运行带来的冲击。论文最后对所取得的主要研究成果进行了总结,并对下一步研究工作进行了展望。
[Abstract]:The construction of a strong smart grid can not be separated from a strong power supply. Only by building a ductile power supply that adapts its development to meet its needs and coordinate its operation, the advantages and benefits of the smart grid can be played. Otherwise, the smart grid can only be a "passive water, a wood free". Large generator sets are the main mains of the power supply, and the smart grid is the construction of smart grid. The key of ductile power supply is the large-scale grid connection of new energy generation with intermittent and random characteristics in the smart grid, which puts forward higher requirements for the support of large conventional energy generating units. At the same time, the application of new power generation and transmission and distribution technology makes the operating environment of the unit more complex, and the operation safety of large units is facing a new challenge. The protection of relay protection is an important safety protection measure for large generators. The construction of the ductile power supply for the smart grid requires the protection of the generator to ensure the safety of the unit, while taking into account the operation safety of the power grid and giving full play to the support function of the large unit to the power grid. The relay protection research of the motor which has an important influence on the operation of the power grid is of great significance to the safety, efficiency and economic operation of the smart grid.
The stator grounding is the most common fault of the generator. The size of the grounding current is the direct indicator of the degree of fault damage. A large generator stator grounding protection based on the grounding current is proposed in this paper. The grounding current is calculated in real time after the fault occurs. Only when it is greater than the safety allowable value, the trip is stopped, otherwise only the notice is issued. The alarm signal, under the premise of guaranteeing the safety of the generator, avoids the impact of the large generator tripping on the stable operation of the power grid. A method of locating the fault of the generator stator grounding fault is proposed, which automatically identifies the fault phase, the fault branch and the fault coil, which greatly reduces the workload of the fault removal and the shutdown time.
Out of step oscillation is one of the most important problems in the interaction and coordination of large units and power grids. This paper puts forward a single machine failure protection scheme for large generators which take into account the safety of the network, fully exerts the capacity of the unit to withstand the oscillation of the step, and strengthens the supporting role of the large unit on the system when the system oscillates. The network safe large generator multi machine lost step protection action strategy, the excision of the least unit makes the system recover synchronously, and avoids the impact of the multi machine tripping on the power grid security. On this basis, the first line of defense and second lines of defense for the generator to cope with the lost step oscillation are formed by the multi machine lost step protection and the single machine step protection respectively.
Anti time protection is an important protection in large generator protection system adapted to the demand of smart grid ductile power supply. This paper analyzes the existing problems of the existing anti time limit protection, and proposes a large generator anti time limit protection based on the optimal fitting of the capability curve, so as to achieve the optimal matching of the action characteristic curve and the generator capacity curve. And its realization algorithm can accurately reflect the dynamic process of generator heat accumulation under abnormal condition. It fully exerts the efficiency of the unit under the premise of ensuring the safety of the unit, and is in line with the ductile demand of the smart grid for the power supply.
The transverse differential protection of the unit parts is an important main protection for the interturn short circuit of large generator. The main problem is to improve the sensitivity of the small turn short of the reaction inside the reaction. The paper studies the mechanism of the unbalance current of the unit transverse difference and influences the factor, and analyzes the principle of the existing unit transverse differential protection. On the basis of this, a criterion for the protection of unit transverse difference based on air gap electromotive force (EMF) is proposed, which is used in conjunction with the existing protection criteria. It can enlarge the coverage of the internal turn short circuit, strengthen the safety defense of the large generator and transport the power grid. The supporting role of a line.
Demagnetization protection is an important network protection protection for the generator. This paper focuses on two key problems of large generator loss protection and power grid coordination. In view of the problem that the rotor side criterion is not stable and reliable, an auxiliary criterion based on the no-load EMF is proposed, and the calculation method and belt of the generator no-load EMF are given. With this auxiliary criterion, the overall scheme of demagnetization protection improves the reliability of the magnetic loss protection in the power grid oscillation and fault. In view of the lack of coordination between the current loss protection and the low excitation limit, the coordination methods, principles and steps between the two are studied. Avoid the impact of loss of excitation protection on the power grid operation.
Finally, the main research results are summarized, and the next research work is prospected.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM307.3

【参考文献】