Abstract
With the rapid development of wind and photovoltaic power generation, hydro-turbine generator units have to operate in a challenging way, resulting in obvious vibration problems. Because of the significant impact of vibration on safety and economical operation, it is of great significance to study the causal relationship between vibration and other variables. The complexity of the hydro-turbine generator unit makes it difficult to analyze the causality of the mechanism. This paper studied the correlation based on a data-driven method, then transformed the correlation into causality based on the mechanism. In terms of correlation, traditional research only judges whether there is a correlation between all data. When the data with correlation are interfered with by the data without correlation, the traditional methods cannot accurately identify the correlation. A piecewise correlation method based on change point detection was proposed to fill this research gap. The proposed method segmented time series pairs, then analyzed the correlation between subsequences. The causality between power load and vibration of a hydro-turbine generator unit was further analyzed. It indicated that when the power load is less than 200 MW, the causality is weak, and when the power load is greater than 375 MW, the causality is strong. The results show that the causality between vibration and power load is not fixed but piecewise. Furthermore, the piecewise correlation method compensated for the limitation of high variance of the maximum information coefficient.
Highlights
IntroductionAs renewable energy is affected by the natural environment, power load often fluctuates [3]
Under the guidance of carbon peak and carbon neutralization, many renewable energy sources such as wind power and photovoltaic have grown rapidly in recent years [1,2].As renewable energy is affected by the natural environment, power load often fluctuates [3]
The measured data came from an hydro-turbine generator units (HTGUs), consisting of a Francis turbine and a verticalmeasured data came from consisting a Francis a vershaftThe semi-umbrella generator, withanaHTGU, rated speed of 125ofr/min andturbine a ratedand power of tical-shaft semi-umbrella generator, with a rated speed of r/min and a rated power of
Summary
As renewable energy is affected by the natural environment, power load often fluctuates [3]. This requires the power grid to have reliable peak and frequency regulation capabilities [4]. Hydropower accounts for a large proportion in Southwest China [7,8]. In this context, HTGUs have to operate in a challenging way, which is in contradiction with the goal of safe and stable operation. Vibration may cause an unstable rotation speed of the HTGUs and unbalanced flow channel pressure, which eventually causes the unit to fail to operate safely and stably [11]. Vibration affects the efficiency of HTGUs [12]
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