含调压室水电站小波动调节品质及影响因素研究

发布时间：2018-11-27 06:57

【摘要】：水力发电机组作为电网中重要的骨干电源,主要承担电网调频、调峰任务,保证其良好的调节品质以及高质量的电能输出具有重要的意义。对于含调压室水电站而言,在小波动过程中,水轮发电机组经常会因为调压室水位波动而产生转速尾波衰减速度过慢等问题,进而影响机组调节品质,这些问题一直是人们关注的焦点。为提高系统调节品质,工程中常将调压室布置在距离水轮机较近的位置,但也常因此带来尾波问题较为严重,甚至为了减小尾波影响不惜增加调压室断面面积,使整个工程的预期投资金额大幅度增加。所以,对于此类水电站,研究分析各因素对含调压室水电站小波动调节品质的影响规律等问题有着重要的工程应用价值和理论指导意义。首先,本文建立了包含压力管道、调压室、尾水隧洞、水轮发电机组、调速器等多个部件在内的调节系统的五阶数学模型。其次,由于五次及以上的方程无法求取解析解,因此需要对原五阶系统进行简化处理。本文通过理论推导和数值仿真分析了各因素对过渡过程中机组转速变化的影响大小,发现压力管道水击压力波引起的机组水头变化对水轮机流量特性的影响不大,忽略后机组转速波动与原系统机组的转速波动过程非常接近,由此将原模型简化为四阶模型;对四阶模型的特征方程进行分解后得到两个二阶环节的叠加,这两个二阶环节分别表征了转速的主波和尾波特征;通过分析这两个二阶环节最终得到了超调量、调节时间等表征调节品质指标的解析表达式,并通过工程实例验证了解析公式的正确性,此研究成果为类似电站提供了参考依据。最后,以调节品质指标的理论表达式为基础,结合工程实例研究了调压室位置、调压室断面面积、调速器参数、发电机及负载自调节系数、机组惯性时间常数等因素对小波动调节品质的影响规律,并通过数值仿真进行了对比验证。
[Abstract]:As an important backbone power supply in the power network, hydroelectric generating units are mainly responsible for the tasks of power network frequency modulation and peak regulation. It is of great significance to ensure its good regulating quality and high quality power output. For the hydropower station with surge chamber, in the process of small fluctuation, the speed coda attenuation speed is too slow due to the fluctuation of water level in the surge chamber, which further affects the regulating quality of the unit. These problems have always been the focus of attention. In order to improve the regulating quality of the system, the surge chamber is often arranged near the hydraulic turbine in engineering, but the coda problem is often serious, even in order to reduce the influence of the coda, the section area of the surge chamber is increased. The expected investment in the whole project has increased substantially. Therefore, for this kind of hydropower station, it has important engineering application value and theoretical guiding significance to study and analyze the influence of various factors on the regulation quality of small fluctuation regulation of hydropower station with surge chamber. First of all, the fifth order mathematical model of regulating system including pressure pipe, surge chamber, tailrace tunnel, turbine generator set, governor and so on is established in this paper. Secondly, because the equations of order 5 and above can not be solved, it is necessary to simplify the original fifth order system. In this paper, through theoretical derivation and numerical simulation, the influence of various factors on the speed change of the turbine during the transition process is analyzed. It is found that the change of the turbine head caused by the water hammer pressure wave of the pressure pipe has little effect on the flow characteristics of the turbine. The speed fluctuation of the unit is very close to that of the original system, so the original model is simplified to the fourth order model. After decomposing the characteristic equations of the fourth-order model, the superposition of two second-order links is obtained. The two second-order links represent the main wave and coda characteristics of the rotational speed respectively. Through the analysis of the two second-order links, the analytical expressions of the overshoot quantity and the regulating time are obtained, and the correctness of the analytical formula is verified by an engineering example. The research results provide a reference for similar power stations. Finally, based on the theoretical expression of regulating quality index, the location of surge chamber, the sectional area of surge chamber, the parameters of governor, the self-regulating coefficient of generator and load are studied in combination with engineering examples. The influence of inertia time constant on the regulation quality of small fluctuation is compared and verified by numerical simulation.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV732.5

【相似文献】