【作者】 任艳杰；

【导师】 赵玉林；

【作者基本信息】 东北农业大学 ， 农业电气化与自动化， 2006， 硕士

【摘要】 在电力系统中,由于无功不足而给系统带来的危害不容忽视,目前低压电网的无功补偿大多采用并联电容器方式。无功补偿电容器的投切器件较多,其投切的平稳度和使用寿命也相差很大,因此投切器件的选择是非常重要的。本文在分析低压无功补偿装置各种投切开关优缺点的基础上,采用集交流接触器和固态继电器(SSR)二者优点于一身的机电一体化复合开关作为电容器的投切开关,研制一种具有无功补偿、电压、电流保护等多种功能的综合自动化装置。此种复合开关采用交流接触器和固态继电器并接的方式,作为电容器投切的执行元件,将电容器投切和运行的不同特性,分为暂态和稳态两个过程,在电容器投切瞬间的暂态过程中采用固态继电器,在电容器投入后和切除前的稳态过程中采用交流接触器。它既具有固态继电器过零投切涌流小,无过电压的优点,又具有接触器主触点导通容量大、无功耗的优点。采用此种开关投切电容器,克服了纯晶闸管电子开关长期承载电容器电流时,功耗大,发热高的缺点。在控制方式上,通过分析,单一控制方式均存在着相应的缺点和不足,因此本研究采用了无功电压复合控制方式,即按无功功率控制,按电压校正。在电压正常波动范围内实现无功基本平衡。其原则是:在保证电压不越限的前提下,也就是把电网电压上限值和下限值作为控制电容器组投切的约束条件,使线路传输的无功功率最小。其控制减少了网络损耗,同时也兼顾了电压的质量。控制系统采用价格比较便宜的AT89C52单片机作为控制系统主体。装置能够实现无功功率的快速、准确补偿功能且成本较低,在低压城网和农网中具有较好的实用性以及广阔的应用前景。更多还原

【Abstract】 In electric power system, the hazard brought by reactive power deficiency must be paid attention to. Now reactive power compensation in low-voltage network mostly employed parallel capacitors. There were many switching device of capacitors and the degree of stability and operating life of which were different, so the selection of switching device was very important. On the basis of analyzing merits and faults of various switches of low-voltage reactive compensation device, electromechanical combination switch which had the merits of AC contactor and the solid state relay (SSR) was employed, and an integrated automation device was studied, which had reactive power compensation and other functions, such as voltage protection and current protection. The actuator of capacitors was combination switch which was constituted of AC contactor and SSR, the different characters of capacitor switching and running was divided two courses, transient state and steady state. In the course of transient state of switching SSR was employed and in the course of steady state after putting into capacitors or before withdrawing capacitors AC contactor was employed. So the switch had the merits of SSR, such as zero switching, little inrush current and no over-voltage. It also had the merits of contactor, such as high conducting capacity of main contacts and no power consumption. Using the switch could overcome the faults of thyristor electronic switch when long-time bearing capacitor current, such as high power consumption and high fever.Through analyzing various control modes,single control mode all existed corresponding faults, so the research adopted voltage and reactive power compound control mode, that was controlling according to reactive power and correcting by voltage. In the normal fluctuation range of voltage it could realize reactive power balance basically. The principle was that reactive power transmission from line was minimal under the precondition that the voltage was not over the bound, it was also said that upper limit value and lower limit value of network voltage were regarded as constraint condition that controlling the switching of capacitors. The control mode reduced the loss of network and gave attention to the quality of voltage at the same time.AT89C52 was a sort of cheap Single Chip Microcomputer and was applied to control system as the main part of reactive power compensation device. This device could rapidly and accurately compensate reactive power and was low-cost. So it had a good practicability and wide application更多还原