一种适用于配电变压器的无触点有载自动调压分接开关

发布时间：2018-06-28 04:50

本文选题：配电变压器 + 无触点　；参考：《东北农业大学》2017年硕士论文

【摘要】：在电力系统无功功率充足的条件下,对配电变压器实现有载自动调压是稳定低压配电系统最直接有效的措施。传统机械式调压分接开关由于动作时有电弧,因此不适合需要频繁调压的配电变压器使用,而处于研究阶段的无触点有载调压分接开关(无触点OLTC)虽然动作时无电弧且可频繁动作,但仍存在以下问题:在现有电力电子元件耐压值低的情况下,仅能对N%5±U分接头实现有载调压,调压范围小,不能满足工程需求;目前研究的无触点OLTC的控制系统位于变压器低压侧,而作为被控制对象的开关执行元件却处在高压侧,当出现高压侧避雷器动作或高压侧单相接地时,OLTC控制系统将因承受高压而击穿;另外在变换分接头过程中,易产生较大环流,致使开关元件或调压绕组因过流而击穿;且没有有效的保护措施,当出现过流、分接开关被击穿等故障时,变压器将停止运行,供电可靠性低。这些问题的存在限制了无触点OLTC的应用及推广。针对上述问题,本文设计出一种无触点OLTC,该装置采用反并联晶闸管模块作为分接开关执行元件,采用正反调压方式进行调压,以扩大调压范围;控制系统电源及测量电压均通过隔离变压器取自配电变压器一次侧靠近中性点的调压绕组两端,使控制系统对地悬浮,解决其耐压问题;同时在高压侧调压绕组非额定分接头与相连的可控硅模块之间串联三相自动空气开关触点,当出现过流时动作,起到过流保护作用;且将每组三相空气开关的第三对触点及隔离变压器一次侧绕组串联在一起,当发生缺相、过流、分接开关被击穿等故障时,自动空气开关无延时跳开,切断故障电流,同时切断控制系统电源,控制系统自动退出,而与额定分接头相连的可控硅模块采用无源自取能触发方式,在控制系统因断电退出工作时,该模块导通,同时非额定档可控硅模块将因失去触发信号而处于截止关断状态,进而使变压器在额定档位正常运行,保证了供电可靠性。以实验室及哈尔滨格瑞德电力成套设备公司现有设施为基础,分别进行了OLTC监控单元调试、OLTC触发电路测试、样机保护功能测试及样机自动稳压测试。实验结果表明,具有无触点OLTC的配电变压器在正常运行时,能够根据电网电压的波动,自动调整负荷输出电压,使输出电压保持在标准范围(N?%3 U)内,并能将调压范围扩大至N?%10 U;而在出现分接开关等故障时,空气开关迅速跳闸,有载调压功能退出,变压器自动恢复到额定档位继续供电运行,实现保护调压绕组和保证供电可靠性的双重功能。
[Abstract]:Under the condition of sufficient reactive power in the power system, it is the most direct and effective measure to stabilize the low voltage distribution system to realize the automatic voltage regulation for the distribution transformer. The traditional mechanical voltage regulating tap switch is not suitable for distribution transformers with frequent voltage regulation because of the arc when it is in action. While the contactless tap switch (OLTC), which is in the research stage, has no arc and can be operated frequently when it is in action, it still has the following problems: when the voltage value of the existing power electronic components is low, It can only adjust the load voltage of the N5 卤U tap, and the voltage range is too small to meet the engineering requirements. The contactless OLTC control system currently studied is located at the low-voltage side of the transformer, while the switch actuator, which is the object under control, is located at the high-voltage side, and the contactless OLTC control system is located at the low-voltage side of the transformer. When the action of high voltage side arrester or single phase grounding of high voltage side occurs, the OLTC control system will break down because of withstanding high voltage, in addition, in the process of changing tap, large circulation will be produced, which will lead to the breakdown of switch element or voltage regulating winding because of overcurrent. There are no effective protection measures. When overcurrent, tap switch breakdown and other failures occur, the transformer will stop operation, and the reliability of power supply will be low. These problems limit the application and popularization of contactless OLTC. To solve the above problems, a contactless OLTC is designed in this paper. The device adopts the anti-parallel thyristor module as the tap switch actuator, and adopts the positive and negative voltage regulation mode to expand the voltage regulation range. The power supply and the measured voltage of the control system are obtained from the primary side of the distribution transformer by isolating transformer at the two ends of the regulating winding near the neutral point to make the control system suspend to the ground and solve the voltage resistance problem. At the same time, the three-phase automatic air switch contact between the non-rated tap of the high-voltage side voltage regulating winding and the connected SCR module is connected in series, which acts as an overcurrent protection when overcurrent occurs. The third pair of contact points of each group of three-phase air switches and the primary side windings of the isolation transformer are connected in series together. When faults such as lack of phase, over-current and breakdown of the tap switch occur, the automatic air switch skips away without delay and cuts off the fault current. At the same time, the power supply of the control system is cut off, the control system automatically exits, and the thyristor module connected to the rated tap adopts the passive self-extraction energy trigger mode. When the control system exits from work because of the power failure, the module is switched on. At the same time, the non-rated SCR module will be cut off due to the loss of trigger signal, which will ensure the reliability of power supply. Based on the existing facilities of the laboratory and Harbin Gered Electric Power complete equipment Company, the OLTC monitoring unit debugging and OLTC trigger circuit testing, the prototype protection function test and the prototype automatic voltage stabilizing test are carried out respectively. The experimental results show that the distribution transformer with contactless OLTC can automatically adjust the load output voltage according to the fluctuation of the grid voltage, so that the output voltage can be kept within the standard range (Nu / 3U) when the transformer with contactless OLTC is in normal operation. The range of voltage regulation can be extended to N? U, and when the tap switch and other faults occur, the air switch trips quickly, the on-load voltage regulation function exits, and the transformer automatically recovers to the rated gear to continue the power supply operation, The dual function of protecting voltage regulating winding and ensuring the reliability of power supply is realized.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM421

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