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Overvoltages and Insulation Requirements
Published in Amitava Sil, Saikat Maity, Industrial Power Systems, 2022
Insulation requirements are essential in high voltage (HV) system and equipment design. Overvoltages in a power system include temporary overvoltages, switching impulse and lightning impulse overvoltages; all are having different peak magnitude and shape of waveforms, although all are transient in nature. Any kind of overvoltage generates stress to the insulation of the electrical equipment and likely to cause damage resulting outage of power supply. Overvoltage caused by surges can result in sparkover and flashover between phase and ground at the weakest point in the network. Overvoltage protective device like surge arrestors or lightning arrestors are designed to withstand a certain level of transient overvoltage beyond which the devices drain the surge energy to the ground and therefore maintain the level of transient overvoltage up to a specific level.
Mitigation Techniques
Published in L. Ashok Kumar, S. Albert Alexander, Computational Paradigm Techniques for Enhancing Electric Power Quality, 2018
L. Ashok Kumar, S. Albert Alexander
When the voltage in a circuit or part of it is raised above its upper design limit, this is known as overvoltage. The conditions may be hazardous. Depending on its duration, the overvoltage event can be transient (a voltage spike) or permanent, leading to a power surge. An overvoltage is a voltage pulse or wave that is superimposed on the rated voltage of the network, which is shown in Figure 2.49. Overvoltage is characterized in Figure 2.50: The rise time tf (in μs)The gradient S (in kV/μs)
Overvoltage and Earthing Protection
Published in Ramesh Bansal, Power System Protection in Smart Grid Environment, 2019
N. T. Mbungu, J. J. Justo, Ramesh Bansal
Overvoltage may cause damage to insulators and substation equipment, so it is necessary to provide a scheme to protect the insulators and other apparatus from the harmful effects of overvoltage. Some devices are available to reduce the amplitude and front steepness of surges. The following protective equipment may be used to protect against the effects of overvoltage: Rod gapSurge diverterOverhead earth wire or shielding conductor
A failure prediction method of power distribution network based on PSO and XGBoost
Published in Australian Journal of Electrical and Electronics Engineering, 2022
Jian Fang, Hongbin Wang, Fan Yang, Kuang Yin, Xiang Lin, Min Zhang
In windy weather, it is easy for power distribution networks to contact surrounding trees or be hooked by foreign matters so as to cause single-phase ground failure. In continuous rainy days, the increase in humidity may affect the insulation performance of the equipment, leading to leakage of current or pollution flashover. Under the action of thunder and lightning, power distribution network-related equipment may suffer overvoltage, current leakage or other failures due to lightning stroke. Therefore, this paper mainly selects weather indexes including gale, precipitation, thunder and lightning as the input of the failure risk prediction model, as shown in Table 2.
Parameter optimisation of support vector machine using mutant particle swarm optimisation for diagnosis of metal-oxide surge arrester conditions
Published in Journal of Experimental & Theoretical Artificial Intelligence, 2019
Chien-Nan Chen, Thom Thi Hoang, Ming-Yuan Cho
Most of the transmission and distribution components may be seriously damaged by overvoltage phenomena. Thus, protection of equipment against overvoltage has been considered by many researchers in order to increase the quality of power systems (Chatterjeea, Bhattacharjeea, & Royb, 2012; Shim & Zaima, 2015; Soloot, Høidalen, & Gustavsen, 2012). Metal-oxide surge arresters are one of the widely used equipment in the field of overvoltage protection. However, the ageing of arrester is dependent on various factors, such as operating voltage and current strain, moisture and superficial pollution, chemical reactions and degradation of varistors. Hence, various approaches are investigated to diagnosis arrester conditions so that alarms are given as long as any fault occurs. The conditions of high voltage metal-oxide surge arresters are monitored by passive surface acoustic wave temperature sensors (Hinrichsen, 1995). Also, intelligent thermal images are used to monitor the surge arrester conditions (Almeida et al., 2009). Besides, monitoring of arrester conditions is performed based on electromagnetic emission at the high ranges of frequency (Wong, 2006). The power loss-based arrester diagnosis is introduced by Coffeen and McBride (1991), in which resistive leakage currents are calculated by obtaining the watts loss of the testing sample. However, the leakage current-based method is the most widely applied for identifying arrester operating conditions (Christodoulou, Avgerinos, Ekonomou, Gonos, & Stathopulos, 2009; Khodsuz, Mirzaie, & Seyyedbarzegar, 2014; Stojanović & Stojković, 2013; Zhu & Raghuveer, 2011). This method can be based on the total leakage current (Shirakawa et al., 1988), resistive leakage current (Ruijin et al., 2000) or the third-order harmonic of the resistive leakage current (Lundquist, Stenstrom, Schei, & Hansen, 1990). Nevertheless, the leakage current analysis methods exhibit some measurement errors because of a phase discrepancy between the line voltage and the obtained resistive current, as well as a hysteresis phenomenon of the V–A characteristics. Moreover, lack of proper features and indicators is also the main restriction of these methods and hence requires intelligent supporting techniques in order to achieve the higher diagnosis accuracy. These supporting techniques may be artificial neuron network (ANN) (Tavares, Neto, Costa, Albuquerque, & Maia, 2009) or support vector machine (SVM) (Khodsuz & Mirzaie, 2015), in which SVM gives the better results as compared to ANN.