随着新能源占比的提升,系统惯性降低、调频资源减少,系统频率稳定问题严峻。因此在新型电力系统运行方式多变的背景下,如何快速精准评估大功率扰动下系统频率安全指标显得尤为重要。其中频率最低值指标由于与多种参数存在高度非线性且...随着新能源占比的提升,系统惯性降低、调频资源减少,系统频率稳定问题严峻。因此在新型电力系统运行方式多变的背景下,如何快速精准评估大功率扰动下系统频率安全指标显得尤为重要。其中频率最低值指标由于与多种参数存在高度非线性且无法显式表达的量化关系而难以实现快速准确预测,是频率稳定安全指标评估的研究重点。然而,目前频率最低值快速预测方法难以考虑调频备用的影响。为此,基于系统频差曲线抛物线近似的假设,对平均系统频率(average system frequency,ASF)模型进行开环解耦,进一步得出系统频率最低值时间与调速器输出功率之间的量化关系,最终实现考虑调频备用容量的频率最低值快速预测方法。该方法在小系统和ACTIVSg2000算例上的预测精度分别为99.28%和97.71%,算例结果证明了算法的有效性。该方法对频率安全约束下机组组合、频率稳定控制措施的有效性评估以及频率稳定约束下系统新能源运行承载能力评估等问题具有重要意义。展开更多
In order to consider the effects of elastohydrodynamic lubrication(EHL) on contact fatigue reliability of spur gear, an accurate and efficient method that combines with response surface method(RSM) and first order sec...In order to consider the effects of elastohydrodynamic lubrication(EHL) on contact fatigue reliability of spur gear, an accurate and efficient method that combines with response surface method(RSM) and first order second moment method(FOSM) was developed for estimating the contact fatigue reliability of spur gear under EHL. The mechanical model of contact stress analysis of spur gear under EHL was established, in which the oil film pressure was mapped into hertz contact zone. Considering the randomness of EHL, material properties and fatigue strength correction factors, the proposed method was used to analyze the contact fatigue reliability of spur gear under EHL. Compared with the results of 1.5×105 by traditional Monte-Carlo, the difference between the two failure probability results calculated by the above mentioned methods is 2.2×10-4, the relative error of the failure probability results is 26.8%, and time-consuming only accounts for 0.14% of the traditional Monte-Carlo method(MCM). Sensitivity analysis results are in very good agreement with practical cognition. Analysis results show that the proposed method is precise and efficient, and could correctly reflect the influence of EHL on contact fatigue reliability of spur gear.展开更多
文摘随着新能源占比的提升,系统惯性降低、调频资源减少,系统频率稳定问题严峻。因此在新型电力系统运行方式多变的背景下,如何快速精准评估大功率扰动下系统频率安全指标显得尤为重要。其中频率最低值指标由于与多种参数存在高度非线性且无法显式表达的量化关系而难以实现快速准确预测,是频率稳定安全指标评估的研究重点。然而,目前频率最低值快速预测方法难以考虑调频备用的影响。为此,基于系统频差曲线抛物线近似的假设,对平均系统频率(average system frequency,ASF)模型进行开环解耦,进一步得出系统频率最低值时间与调速器输出功率之间的量化关系,最终实现考虑调频备用容量的频率最低值快速预测方法。该方法在小系统和ACTIVSg2000算例上的预测精度分别为99.28%和97.71%,算例结果证明了算法的有效性。该方法对频率安全约束下机组组合、频率稳定控制措施的有效性评估以及频率稳定约束下系统新能源运行承载能力评估等问题具有重要意义。
基金Project(CX2014B060)supported by Hunan Provincial Innovation for Postgraduate,ChinaProject(8130208)supported by General Armament Pre-research Foundation,China
文摘In order to consider the effects of elastohydrodynamic lubrication(EHL) on contact fatigue reliability of spur gear, an accurate and efficient method that combines with response surface method(RSM) and first order second moment method(FOSM) was developed for estimating the contact fatigue reliability of spur gear under EHL. The mechanical model of contact stress analysis of spur gear under EHL was established, in which the oil film pressure was mapped into hertz contact zone. Considering the randomness of EHL, material properties and fatigue strength correction factors, the proposed method was used to analyze the contact fatigue reliability of spur gear under EHL. Compared with the results of 1.5×105 by traditional Monte-Carlo, the difference between the two failure probability results calculated by the above mentioned methods is 2.2×10-4, the relative error of the failure probability results is 26.8%, and time-consuming only accounts for 0.14% of the traditional Monte-Carlo method(MCM). Sensitivity analysis results are in very good agreement with practical cognition. Analysis results show that the proposed method is precise and efficient, and could correctly reflect the influence of EHL on contact fatigue reliability of spur gear.
