基于光纤触发的无触点有载自动调压技术的研究

发布时间：2018-03-30 05:28

本文选题：无触点有载调压　切入点：变压器　出处：《东北农业大学》2015年硕士论文

【摘要】：电网电压存在波动,负荷变化也会影响电网电压,从而不利于用电设备长期稳定运行。在无功功率充足的情况下,变压器调压是最直接有效的稳压措施。本课题所在项目“无触点有载自动调压配电变压器”研制出一种以反并联晶闸管为分接开关的无触点有载调压配电变压器,其容量为50k VA,使之带不同性质负荷进行试验,最终解决了样机调压可靠性问题,并达到了稳压目的。然而,变压器高压侧绕组如果发生单相接地故障,位于高压侧的反并联晶闸管和低压侧的控制系统间将承受较大的高压侧相电压。当前所使用的位于接口处的电源变压器及光电耦合器的绝缘效果无法满足该耐压要求。光纤具有良好绝缘效果,在晶闸管的触发问题上具有一定的应用价值与发展潜力。本文所进行的基于光纤触发的无触点有载自动调压技术的研究就是利用光纤触发技术以彻底解决变压器高低压侧绝缘问题。调压系统以STC89C52RC单片机为控制中心,将采集处理后所得的低压侧相电压与设定的额定值作比较,根据需要发出控制信号经光纤传送给高压侧的触发电路以完成分接开关的切换,起到有载自动调压的作用,稳定变压器输出电压。本文以高耐压的反并联晶闸管为分接开关,设计了四种主接线方案。通过方案的选择比较,最终确定了全电力电子式主电路设计,该设计采用光纤触发反并联晶闸管及光纤触发双向晶闸管启动机构,不仅解决了变压器高低压侧间电气隔离问题,同时也克服了机械触点固有缺陷。通过分析变压器不平衡运行时高压侧各相电压偏移中性点程度,同时根据实际需要,确定了晶闸管的型号,并设计了RC缓冲保护电路。光纤采用了配套的HFBR-1521型发送器、HFBR-2521接收器。本文设计了反并联晶闸管光纤触发电路,同时设计了基于光纤触发的启动电路。通过光纤进行控制信号的传输,保证了变压器高低压侧的良好电气隔离效果。触发电路与启动电路可靠运行的重难点在于高压直流电源的获取。本设计利用加在处于截止状态下的分接开关的交流电压进行整流滤波稳压得到所需直流电源。根据运行原理,针对电子元器件进行了选型及参数设置,并通过实验验证。在控制单元上,从硬件系统与软件系统入手,分别在原有基础上加于改进,以配合光纤触发信号。由于启动机构与触发电路在给与光信号的情况下动作恰好相反,故在分接开关转换子程序中加以修改,以使反并联晶闸管与双向晶闸管正确动作,完成启动与调压的过程。在实验室模拟试实验中,先后进行了反并联晶闸管光纤触发实验、光纤触发启动实验及整体实验,结果表明基于光纤触发的无触点有载自动调压装置能够实现基本调压功能,并且解决了配电变压器高低压侧电气隔离问题,这对于现今全电力电子型有载调压变压器推广使用具有重要意义。
[Abstract]:The fluctuation of power grid voltage and the change of load will affect the voltage of the power network, which is not conducive to the long-term stable operation of the power equipment. In the case of sufficient reactive power, Transformer voltage regulation is the most direct and effective voltage regulation measure. This project, "Non-contact on-load automatic voltage regulating distribution transformer", has developed a non-contact on-load voltage regulating distribution transformer, which takes anti-parallel thyristor as tap switch. Its capacity is 50kVA, which makes it carry on the test with different properties of load, finally solves the reliability problem of the prototype voltage regulation, and achieves the purpose of voltage stabilization. However, if the single-phase grounding fault occurs in the high-voltage side windings of the transformer, The antiparallel thyristor at the high voltage side and the control system on the low voltage side will bear a large voltage at the high voltage side. The insulation effect of the current power transformer and photocoupler located at the interface can not meet this voltage. Requirements. Optical fiber has good insulation effect, It has certain application value and development potential in the trigger of thyristors. The research of no-contact load automatic voltage regulation based on fiber-optic trigger in this paper is to make use of fiber-optic trigger technology to solve transformer thoroughly. High and low voltage side insulation problem. Voltage regulation system with STC89C52RC single chip microcomputer as the control center, Comparing the phase voltage of low-voltage side after acquisition and processing with the rated value, and sending out the control signal to the trigger circuit of high-voltage side through optical fiber according to the need, so as to complete the switch of tap switch, and play the role of automatic voltage regulation on load. The output voltage of transformer is stabilized. In this paper, four kinds of main wiring schemes are designed by using high voltage reverse parallel thyristor as tap switch. Through the selection and comparison of the schemes, the design of all-power electronic main circuit is finally determined. This design not only solves the problem of electrical isolation between high and low voltage side of transformer, but also adopts optical fiber trigger reverse parallel thyristor and fiber optic trigger bidirectional thyristor starting mechanism. At the same time, it overcomes the inherent defects of mechanical contact. By analyzing the degree of voltage offset neutral point of each phase in the unbalanced operation of transformer, the type of thyristor is determined according to the actual needs. The RC buffer protection circuit is designed. The HFBR-1521 transmitter and HFBR-2521 receiver are used in the optical fiber. The anti-parallel thyristor fiber trigger circuit is designed in this paper. At the same time, the starting circuit based on fiber-optic trigger is designed. The high and low voltage side of transformer has good electrical isolation effect. The most difficult point for the reliable operation of trigger circuit and startup circuit lies in the acquisition of HVDC power supply. The current voltage is rectified and filtered to stabilize the voltage to obtain the required DC power supply. The type selection and parameter setting of electronic components are carried out and verified by experiments. In the control unit, the hardware system and the software system are respectively applied to the improvement on the original basis. Because the action of the starting mechanism and the trigger circuit is just opposite when the light signal is given, it is modified in the tap switch conversion subroutine to make the anti-parallel thyristor and the bi-directional thyristor operate correctly. In the laboratory simulation experiment, the anti-parallel thyristor fiber trigger experiment, the optical fiber trigger start experiment and the whole experiment have been carried out. The results show that the no-contact on-load automatic voltage regulating device based on fiber-optic trigger can realize the basic voltage regulation function and solve the electrical isolation problem of the high and low voltage side of the distribution transformer. This is of great significance to the popularization and use of all-power electronic load-regulated transformers.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM421

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