【作者】 李文清；

【导师】 赵志衡；

【作者基本信息】 哈尔滨工业大学 ， 电机与电器， 2006， 硕士

【摘要】 电力电容器通常作为无功补偿装置广泛应用于各变电所及工厂内。长期以来,监控电力电容器的运行电压基波值一直是电容器保护的主要内容。但近年来的统计资料表明,电网谐波会使电容器介质加速老化,发生提前失效,进而造成电网的短路故障。因谐波原因而造成的电容器损坏占40%,而目前国内的保护装置均未计及谐波因素。本文分析并联电容器组常见的各种故障及非正常运行情况,针对电容器组的不同接线方式研究电容器保护的原理,并结合国标中的有关规定,以运行电压不大于1.1倍额定电压为判据,给出各保护功能投退动作整定值的计算方法。理论分析谐波对电容器运行参数的影响,以电容器电容量损耗10%作为失效判据,建立电容器寿命预测模型,并研究谐波累加下的电容器寿命预测方法。选用以TI公司的DSP2407为核心的硬件平台,编程实现电力电容器的相间短路保护、线路过电压保护、过电流保护、过负荷保护、过电压保护等常规保护功能。采用128点FFT算法对电网电压进行谐波分析,获得电压波形系数,进而对电容器寿命进行在线预测。将DSP应用于电容器保护装置,实现各项保护功能,运行人员可依据电容器的实际运行接线方式,方便的选择投退。同时,电容器寿命预测功能的实现,避免了提前失效的电容器再次投入电网运行,可有效的避免后继事故的发生,对于电容器的稳定运行,具有指导意义。更多还原

【Abstract】 Power capacitor is usually used as var compensator in various sub-stations and factories. For a long time, monitoring the fundamental wave value of running voltage of power capacitor has been considered the main subject in capacitor protection. But recent statistics shows that electrical harmony would accelerate the aging of capacitor, cause damages to the electrical system, and then arouse severe short circuit failure. 40 percent failures of the capacitors are caused by electrical harmony. However, none of the protection device in our country has taken the harmonic factor into account.This paper analyses conventional failures and abnormal operating cases of parallel capacitor, studies the protection theories corresponding to different electrical connections, and discusses the threshold when to apply one protection function according to the national standard that operating voltage can’t get over 1.1 times as rating voltage.This paper studies the influences of the harmonic wave upon the operational parameters of the capacitor, and then sets up a life-span model for capacitors within 10 percent of capacitor loss. Finally, a method which can be used to forecast the life span of capacitors under the accumulation of harmonic wave has been worked out.With the hardware device which uses the TI product DSP2407 as hardcore, such functions have been implemented: interphase short-circuit failure protection, over-voltage protection, over-current protection, over-load protection and etc. we have analyzed the harmonic wave of power line using the 128-dot FFT arithmetic, and got the Voltage Wave Coefficient. After this we can forecast the capacitor life-span online.Using the DSP chip as controlling unit in the capacitor protection device to achieve various functions, the user can cast or cancel one function according to the practical connections of capacitors. The capability of forecasting the life-span of capacitor which can avoid disabled capacitors being put into the power system again and causing subsequent accidents, has a significance for the stabilities of the working capacitors.更多还原