感应电机电压跌落临界清除时间解析算法及应用

发布时间：2018-01-15 17:28

本文关键词：感应电机电压跌落临界清除时间解析算法及应用　出处：《山东大学》2014年博士论文　论文类型：学位论文

【摘要】：随着我国工业的蓬勃发展,有越来越多的感应电动机应用于工业生产,其在工业负荷中所占的比例高达90%以上。感应电动机运行良好与否,已经成为影响工业生产连续性的重要因素。而影响感应电动机最主要的电能质量问题就是电压跌落。相关统计数据表明,由电压跌落引起的用户投诉占整个电能质量问题投诉数量的80%以上。电压跌落影响工业感应电动机的主要表现是造成大量的非必要停机。现代高度自动化的工业生产过程一旦中断,将会造成巨大的经济损失甚至危害人身安全。而另一方面,绝大多数电压跌落的幅值都在其额定电压幅值的80%左右且其持续时间仅为4-10周期,考虑到感应电动机及其负载本身所具有的惯性,感应电动机自身有能力穿越这些电压跌落并恢复稳定运行。因此,工业用户有强烈的愿望来改善感应电动机的保护,避免因电压跌落造成生产过程不必要的中断。此外,随着感应发电机的大量装备及电力系统负担的不断加重,感应发电机的大扰动稳定问题和电网的短期电压稳定问题日益突出,迫切需要有效的方法来对这些稳定问题进行快速评估。要实现这些需求,必须首先快速计算出感应电机在遭遇电压跌落时其能够穿越的最长时间。解析算法因具有物理概念明确、计算速度快等一系列独特优点,是实现快速、准确在线计算的理想选择。因此,从理论上推导出评估感应电机电压跌落穿越能力的解析算法,无疑具有重要的现实意义。本文在分析了电压跌落持续期间和电压跌落消除后感应电动机的动态响应之后,结合电磁转矩与负载转矩之间的稳定和不稳定平衡交点的概念,提出了感应电动机电压跌落临界清除时间的概念来衡量感应电动机电压跌落穿越的能力。针对电力系统中危害程度最为严重的三相对称电压跌落,分别为恒转矩负载特性、恒功率负载特性和风机类负载特性推导出了各自的感应电动机对称电压跌落临界清除时间解析算法及临界转差率的计算公式。此外还提出了感应电动机绝对安全电压跌落的概念及判断某一对称电压跌落是否是绝对安全的判定方法,以及最小绝对安对称全电压跌落的概念及其计算方法。仿真实验和参数敏感分析仿真实验都证实了对称电压跌落临界清除时间解析算法与绝对安全对称电压跌落判定方法的有效性和准确性。针对电力系统中出现次数最多的非对称电压跌落,通过分析感应电动机在非对称电压跌落期间的正负序稳态等效电路及其正负序电磁转矩,提出了总电磁转矩的Ⅰ类和Ⅱ类简化表达形式,并利用不同电磁转矩表达式分别为恒转矩负载特性、恒功率负载特性和风机类负载特性推导出了各自的非对称电压跌落临界清除时间解析算法。此外还提出了判断某一非对称电压跌落是否是绝对安全的判定方法。通过仿真实验验证了所提出的感应电动机非对称电压跌落临界清除时间解析算法和绝对安全非对称电压跌落判定方法的有效性和准确性。为了便于解析算法实际应用于感应电动机的电压跌落保护,本文提出了利用递推最小二乘法来在线辨识电压跌落发生前后感应电动机上游供电网络等效电路的等效参数和感应电动机总体机械负载参数的方法。为辨识非对称故障期间上游供电网络正负序等效参数而提出了获取感应电动机定子正、负序瞬时电压矢量和瞬时电流矢量的方法。为辨识总体机械负载参数利用扩展卡尔曼滤波来估计感应电动机的电磁转矩。之后利用一个实际配电系统模型来模拟配电系统中可能真实发生的故障来仿真验证参数辨识方法和感应电动机电压跌落临界清除时间解析算法的有效性和准确性。本文最后分析了机端故障发生时和消除时感应发电机暂态电磁过程对临界清除时间的影响。根据暂态电磁转矩公式分析了机端三相金属性故障发生时和消除时因感应电动机电磁暂态过程而造成的加速面积变化及计算方法,并推导出了这两个暂态过程所对应的补偿时间的计算公式。提出了计及感应发电机暂态过程的临界清除时间保守计算解析方法。通过仿真实验验证了所提出考虑感应发电机暂态过程的临界清除时间解析算法的有效性和准确性。本文提出的感应电机电压跌落临界清除时间解析算法不仅有助于工业用户实现感应电动机电压跌落的智能保护,还可以用于分析、研究感应发电机大扰动稳定性及考虑感应电动机负荷的系统短时电压稳定性等问题,具有重要的理论意义和实用价值。
[Abstract]:With the development of China ' s industry , more and more induction motors are used in industrial production . In order to meet these demands , it is necessary to quickly calculate the longest time that the induction motor can traverse when the voltage falls . The analytical algorithm is ideal for fast , accurate and on - line calculation because of its definite physical concept and fast calculation speed . Therefore , it is of great practical significance to theoretically deduce the analytical algorithm for evaluating the voltage drop - through ability of induction motor . After analyzing the dynamic response of the induction motor after the voltage sag and the voltage drop elimination , the concept of the critical clearance time of the voltage drop of the induction motor is put forward based on the concept of the point of intersection between the electromagnetic torque and the load torque . In this paper , the positive and negative sequence steady state equivalent circuit and positive negative sequence electromagnetic torque of the induction motor during the asymmetrical voltage sag are analyzed by analyzing the positive and negative sequence steady state equivalent circuit and positive negative sequence electromagnetic torque of the induction motor in the asymmetrical voltage sag . In order to facilitate the practical application of the analytical algorithm to the voltage drop protection of induction motors , this paper presents the method of obtaining the equivalent parameters of the equivalent circuit of induction motor and the general mechanical load parameter of induction motor by using recursive least square method . To identify the positive and negative sequence equivalent parameters of the upstream power supply network during the asymmetric fault , the method of obtaining positive and negative sequence transient voltage vectors and instantaneous current vectors of induction motor is proposed . In this paper , the influence of the transient electromagnetic process of induction generator on the critical clearance time is analyzed in this paper . The calculation formula of the acceleration area caused by the electromagnetic transient process of induction motor is analyzed according to the transient electromagnetic torque formula , and the calculation formula of the compensation time corresponding to the two transient processes is deduced . The method for calculating the critical clearance time of the transient process of the induction generator is presented . The validity and accuracy of the critical clearance time resolution algorithm for the transient process of induction generator are verified by simulation experiments . The analysis algorithm not only helps the industrial users realize the intelligent protection of the voltage drop of induction motors , but also can be used to analyze and study the large disturbance stability of the induction generator and the short - time voltage stability of the system considering the induction motor load , and has important theoretical significance and practical value .

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM346

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