电力工程专业毕业论文.doc

毕业设计 变电站断路器机械特性监测系统设计 摘 要 对电力设备进行在线监测，是实现设备预知性维修的前提，是保证设备安全可靠运行的关键，也是对传统离线预防性试验的重大补充和新的发展。高压断路器所造成的事故无论是在次数，还是在事故所造成的停电时间上都占据总量60％以上。因此，及时了解断路器的工作状态对提高供电可靠性有决定性意义；并可以大大减少盲目定期检修带来的资金浪费。 本文论述了断路器机械特性参数的监测方法；提出根据断路器生产厂家提供的断路器额定短路电流分断次数，计算每次分闸对应的触头电寿命损耗，预测触头电寿命；提出根据断路器壳体温度和断路器周围空气温度结合断路器的热阻来计算断路器主触头稳态温升的方 法，并根据此时的负荷电流间接计算主触头回路的电阻；在实现在线监测的系统的设计上本文选用了美国 TI 公司最新推出的一种功能强大的单片机MSP430。在系统设计时充分考虑到由于该单片机的低供电电压（1.8～3.6V）给设计所带来的特殊问题，并予以解决。在通讯模块设计中根据RS-485 通信芯片MAX1480B 的特殊结构，解决了不同工作电压芯片RS-485 通信芯片MAX1480 与单片机MSP430 的接口问题，并给出了MAX1480 与MSP430 芯片直接联接的接线方案。 关键词：断路器 在线监测 机械特性 触头电寿命 触头温度 On-line Monitoring of HVCB Abstract HVCBon-linemonitoring isessentialforpredictingmaintenance and as a supplement to the traditional off-line preventive maintenance is the key factor of its reliable operation. In fact, the faults on HVCB account for over 60 percent both in number and duration of all the faults occurring in a substation. Therefore, on-line monitoring ofHVCB could significantly improvepower supply reliability and greatly reduce the expense for regular overhaul. In this thesis, the inspecting methods of HVCB mechanical characteristics are discussed. According the shut-off times of HVCB at rated short circuit given by manufacturer,the contacts life loss can be calculated for each operation, and the remaining life can be forecast. In this thesis, an indirect method is proposed for determining the main contact temperature based on the breaker shell temperature, air circumference temperature and breaker’s heat resistance, and furthermore, determining the main contact esistance provided the load current is know. The on-line monitoring ris implemented with MSP430, a new Single Chip Microcomputer by Texas Instrument, with its lower supply voltagerange of this chip （1.8～3.6V）is well treated. In the design of communication module, interfacing problem caused by different voltage supply levels (MAX1480 and MSP430) is carefully solve