高压开关柜是电力系统中使用量最大的控制和保护设备。实现高压开关柜的在线监测与故障诊断，不仅可以实现状态维修，减少停电时间和维修费用，对于高压开关设备智能化和电力系统自动化也具有重要意义。本文研究、开发出了功能上较完善的高压开关柜在线监测与故障诊断系统。该系统为双单片机系统，通过对线圈电流、断路器行程、母线电流、断路器操作电压、储能电机电流、隔离触头温升、柜内温度和湿度等十九路模拟量和三路开关量信号的采集、分析和计算，得到的波形和特征参数可以较全面地反映高压开关柜的状态。包括断路器的状态、隔离插头的接触情况以及开关柜内的环境状况等。其中与断路器有关的状态有：操动回路状态、断路器机械特性和电气特性、储能机构状态等。该系统还能够自动控制加热器和风机以调节柜内的温度和湿度，通过按键实现断路器的分合闸操作。该系统在清华大学高压电器实验室和北京开关厂进行了功能和性能实验，在电科院进行了高压大电流的开断实验、高低温实验和常规电磁兼容实验。实验结果表明该系统的软硬件设计符合原订功能的要求，并满足高压开关柜现场运行的条件。对于隔离触头温升的监测，本文采用的是通过热电偶测得的隔离触头外绝缘套筒地电位端的温升进行估算的间接方法。通过温升实验研究了二者之间的关系，确定了通过后者估算前者的公式。这种方法经济实用，并且不影响开关柜的绝缘。本文对现有的计算断路器剩余电寿命的开断电流加权累计法进行了改进。改进后的计算公式中考虑了各相的燃弧时间，从而提高了准确度。文中给出了利用电寿命实验数据估算改进后的公式中所需参数的方法。本文提出了在真空灭弧室内安装由小型放电间隙构成的传感器的方法来实现真空度的在线监测。并研究了悬浮电位的尖－板间隙在1.0×105~6.7×10-3Pa范围的真空度下的放电现象，得出了起始放电电压与真空度之间的关系。为该方法的应用进行了基础性的探索。本文还研究了由于母线连接处接触不良及开关柜内绝缘不良产生的局部放电现象。实验表明，使用多匝线圈制成的磁场探头测得的放电信号的强度可以反映这两类故障及其程度。该方法具有故障定位和干扰识别能力。

High voltage switchboard’s quantity is the biggest one among the control and protection apparatus in the power system. The realization of the on-line condition monitoring and failure diagnosis of high voltage switchboard not only can realize the condition maintenance, reduce the power outage time and maintenance cost, but also has important significance for improving the intelligent level of high voltage switchboards and automatization extent of the power system. In this dissertation, the on-line condition monitoring and failure diagnosis technique for high voltage switchboard was studied, and an on-line monitoring system has been developed, the function of which is comprehensive. Dual MCU (Micro programmed Control Unit) were adopted in the system. 19 channels analog signals and 3 channels switch signals were sampled by the system, such as coil current, contact displacement of the circuit breaker, breaking current, operation voltage of the circuit breaker, energizing electromotor’s current, isolation contacts’ temperature rise, inner temperature and humidity of the cabinet. The waveforms and characteristic parameters derived from these signals can reflect the condition of the high voltage switchboard roundly, including the condition of the circuit breaker (the condition of the operation circuit, the mechanical and electrical characteristic, the status of the energizing system, etc), the contact status of the isolation contacts, and the environment status in the cabinet. This system can automatically control the heater and fan to adjust the temperature and humidity in the cabinet, and realize the operation of the circuit breaker through keyboard. Function and property tests for this system have been carried out in Tsinghua University High Voltage Apparatus Lab and Beijing Switchgear Factory. High-low-temperature test, high voltage large current breaking test and general EMC tests have been carried out in China Electric Power Research Institute. The results indicated that the hardware and software design of this system functionally meets the preconcerted requirement and characteristically fits the fieldwork condition.The temperature rise of the isolation contacts was computed from the earthing end’s temperature rise of the outer insulation sleeves of the contacts. The temperature rise was measured by thermocouple. Through temperature rise experiment, the relation between the two temperature rises was confirmed, and the calculating formula was derived. This method is economical and practical, and the insulation of the high voltage switchboard is not affected. In this dissertation, the calculating method of remnant electrical life —— breaking current weight accumulation has been improved. In the reformative formula, the arcing time was considered and so the precision of the result was increased. The evaluating method of the parameter needed in the new formula according to the data from electrical life test was given out in the paper. An on-line monitoring method for the vacuum degree of the vacuum interrupter was brought up in this dissertation, which is setting a sensor made by a small partial discharge gap in the interrupter. To study the discharge phenomena occurring in the discharge gap, experiments were made under the vacuum degree of 1.0×105~6.7×10-3Pa, and the relation between the beginning voltage of partial discharge and vacuum degree was derived. This was the primary exploring of the application of this method. This dissertation also researched the partial discharge caused by the bus connection failure and insulation failure inner the high voltage switchboard. The experiment revealed that the intensity of the partial discharge signal detected by a multi-turn coil could reflect these failures and their extent. This method has the capability of fault location and interference identification.