基于暂态信号的中压配电网绝缘监测技术

介绍了利用中压配电网绝缘劣化过程中的瞬时性绝缘参数来评估线路绝缘状态的监测模式。建立了基于暂态信号的中压配电网绝缘监测模型,提出了线路绝缘劣化值的计算过程以及利用绝缘劣化指数监视线路绝缘状态的新方法。以福建省泉州电业局的实际故障数据为例对绝缘监测模型进行了验算,验算结果表明,该模型能够实时、有效地监测中压配电网的总体绝缘状态,并能在线路绝缘劣化到较严重的程度时发出警示信号。

绝缘监测定位系统应用于IT系统的必要性

IT不接地系统与大地之间不直接连接,电气装置的外壳通过保护接地线与接地极连接,由于电气装置与电源端没有直接的连接,当系统出现第一次故障时,接地故障电流仅为非故障相对地的电容电流,故障电流小,电气设备金属外壳不会产生危险性的接触电压(外露导电部分对地电压不超过50V),因此无需切断电源,使电气设备继续运行,并可通过报警装置及检查消除故障,正因为IT不接地系统具备供电稳定性以及低故障电流的特性,IT系统广泛的应用于海上采油平台、煤矿、医疗等行业。IT系统发生第一次故障虽然不影响系统运行,若发生第二次故障时应自动切断电源,当在另一相线或中性线上发生第二次故障时,必须快速切除故障,因为当第二次故障相与第一次故障相为不同相时,会发生严重的短路故障,因此需要在发生第二次故障前找出故障点,所以对于IT系统的绝缘监测及故障查找非常有必要。

Fiber Laser Sensor Based on a Phase-Shifted Chirped Grating for Acoustic Sensing of Partial Discharges

Acoustic emission monitoring is often used in the diagnosis of electrical and mechanical incipient faults in the high voltage apparatus. Partial discharges are a major source of insulation failure in electric power transformers, and the differentiation from other sources of acoustic emission is of the utmost importance. This paper reports the development of a new sensor concept - a fiber laser sensor based on a phase-shifted chirped fiber grating - for the acoustic emission detection of incipient faults in oil-filled power transformers. These sensors can be placed in the inner surface of the transformer tank wall, not affecting the insulation integrity of the structure and improving fault detection and location. The performance of the sensing head is characterized and compared for different surrounding media： air, water, and oil. The results obtained indicate the feasibility of this sensing approach for the industrial development of practical solutions.