Study on Electrical Characteristics of Metal-Oxide Surge Arresters in Medium Voltage Power System

2014 ◽  
Vol 960-961 ◽  
pp. 1073-1076
Author(s):  
Li Zhang ◽  
Kun Yang ◽  
Li Mei He

The index system for electrical characteristics of metal-oxide surge arresters is proposed and established, which is based on rated voltage (Ur), continuous operating voltage (Uc), nominal discharge current (In), overvoltage protection and insulation coordination including lightning overvoltage protection level, operating overvoltage protection level and coordination coefficient (Ks). The study considers both selection and application of overvoltage protection devices for the electrical equipments in 3-35kV medium voltage power system, and comparatively calculates and analyzes the main parameters between two types metal-oxide surge arresters (without gaps and containing series gapped structures), and illustrates their technical features and puts forward suggestions on how to improve the effective utilization. The results of 10kV power distribution system are simulated to show that the conclusions are feasible and available in the practical engineering application.

Author(s):  
A. E. Omoroghomwan ◽  
S. O. Igbinovia ◽  
F. O. Odiase

The major aim of any power system is the continuous provision of safe, quality and reliable electric power to the customers. One of the greatest challenges to meeting up with this goal is the failure of components in the system. In this article, the frequency of outages caused by failure of different components in the distribution system was investigated to ascertain the ones that are more susceptible to failure by comparing their proportions in the entire failure events. The outage data obtained from Irrua Transmission Station comprising Ehor, Ubiaja and Uzebba 33kV feeders were analyzed using Microsoft Excel while the hazard rates were measured using the failure rate index. Findings revealed that 93.77% of all the forced outages in the distribution subsystem in the power sector are caused by the high exposure rate of the bare aluminum conductors used in the construction of the various overhead feeders. Subsequently, the yearly failure rates of aluminum conductors, cross arms, relay, insulators, fuses, electric poles, breakers, transformers, isolators, cables lightning surge arresters were found to be 836.0, 17.5, 17.0, 10.3, 4.3, 2.0, 1.5, 1.3, 1.0, 0.5 and 0.3 respectively in the studied network. A comparison between this study and a related work showed that the rural feeders are more prone to faults as compared to the ones in the urban areas. It was therefore recommended that regular tree trimming along the network corridor should be done. Proper conductor size should be used in every subsequent construction and every segment with undersized conductor should be replaced with the appropriate size. This study will help the power system engineers in the design, construction, maintenance and operation of the distribution power system for optimum and improved system performance.


Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3843
Author(s):  
Sultan Sh. Alanzi ◽  
Rashad M. Kamel

This paper investigates the maximum photovoltaic (PV) penetration limits on both overhead lines and underground cables medium voltage radial distribution system. The maximum PV penetration limit is estimated considering both bus voltage limit (1.05 p.u.) and feeder current ampacity (1 p.u.). All factors affect the max PV penetration limit are investigated in detail. Substation voltage, load percentage, load power factor, and power system frequency (50 Hz or 60 Hz) are analyzed. The maximum PV penetration limit associated with overhead lines is usually higher than the value associated with the underground cables for high substation voltage (substation voltage = 1.05 and 1.04 p.u.). The maximum PV penetration limit decreases dramatically with low load percentage for both feeder types but still the overhead lines accept PV plant higher than the underground cables. Conversely, the maximum PV penetration increases with load power factor decreasing and the overhead lines capability for hosting PV plant remains higher than the capability of the underground cables. This paper proved that the capability of the 60-Hz power system for hosting the PV plant is higher than the capability of 50 Hz power system. MATLAB software has been employed to obtain all results in this paper. The Newton-Raphson iterative method was the used method to solve the power flow of the investigated systems.


2019 ◽  
Vol 217 ◽  
pp. 01020 ◽  
Author(s):  
Margarita Chulyukova ◽  
Nikolai Voropai

The paper considers the possibilities of increasing the flexibility of power distribution systems by real-time load management. The principles of the implementation of special automatic systems for this purpose are proposed. These systems enable some loads of specific consumers of the power distribution system switched to islanded operation to “shift” from the daily maximum to the minimum, which makes some generators available to connect certain essential consumers disconnected earlier by under-frequency load shedding system to the power system. The approach under consideration is illustrated by a power system with distributed generation.


Author(s):  
Zuhaila Mat Yasin ◽  
Izni Nadhirah Sam’ón ◽  
Norziana Aminudin ◽  
Nur Ashida Salim ◽  
Hasmaini Mohamad

<p>Monitoring fault current is very important in power system protection. Therefore, the impact of installing Distributed Generation (DG) on the fault current is investigated in this paper. Three types of fault currents which are single line-to-ground, double line-to-ground and three phase fault are analyzed at various fault locations. The optimal location of DG was identified heuristically using power system simulation program for planning, design and analysis of distribution system (PSS/Adept). The simulation was conducted by observing the power losses of the test system by installing DG at each load buses. Bus with minimum power loss was chosen as the optimal location of DG. In order to study the impact of DG to the fault current, various locations and sizes of DG were also selected. The simulations were conducted on IEEE 33-bus distribution test system and IEEE 69-bus distribution test system. The results showed that the impact of DG to the fault current is significant especially when fault occurs at busses near to DG location.</p>


2013 ◽  
Vol 791-793 ◽  
pp. 1889-1891
Author(s):  
Yan Li Fan ◽  
Qing En Li

The low-voltage distribution system is the key component of the electrical power system. Some analysis and research of the low-voltage distribution system is carried out in this paper, which provides some scientific basis to design the low-voltage distribution system. Firstly, the summarize of low-voltage distribution system is taken. The influence to productions and livings of low-voltage distribution system is introduced. Secondly, the mode of connection and design philosophy of low-voltage distribution system is studied in detail, especially the high-rise buildings low-voltage distribution system is concluded and summarized.


2011 ◽  
Vol 368-373 ◽  
pp. 3344-3347 ◽  
Author(s):  
Wei Sun ◽  
Yong Li ◽  
Di Lu ◽  
Xiao Guo Zhao ◽  
Ying Yu

The surge protective device (SPD), as buildings over-voltage protective device, has been widely used in building’s power distribution system. A novel SPD based on hollow cathode effects is designed. In both air and nitrogen gas, the relationship of discharging voltage and gas pressure are measured, and the critical pressure ranges are determined in the condition of UpUp is pulse voltage protection level). The results indicate that, in the condition of the gap distance D=3 mm and the small hole diameter φ=3 mm, the operating gas pressure ranges are from 50 to 5×104 Pa. With the gap distance D increasing, the pulse voltage protection level Up is decreasing slightly. While D=3 mm, φ=3 mm, and gas pressure (nitrogen) is 600 Pa, the DC voltage protection level and pulse protection level are 784 V and 2.4 kV, respectively. In the action of 10/350 µs pulse current waveform, the quantity of transferred charge Q is 48.26 C, and the ratio energy W/R is up to 2 MJ/Ω. The results testify that the design of SPD in this paper can be used as buildings class B over-voltage protection.


2019 ◽  
Vol 10 (1) ◽  
pp. 26-37
Author(s):  
Redaksi Tim Jurnal

Distribution system is very important in the distribution of electric power to the load. Therefore, a good and efficient distribution system is needed. The underlying cause of poor electric power distribution system is the amount of voltage drop values in the existing system. In the electric power distribution, 20 kV medium-voltage and 380/220V low voltage networks are used. The distribution system of Gandum Feeder in Angke Substation uses medium-voltage network with Underground Cable channel. They are used because of the towering buildings and the dense population in the area. It is known that the longest the channel and the load current are, the greater the voltage drop. From the result of the voltage drop calculation of Feeder Gandum in Angke Substation, which uses manual calculation and ETAP 12.6.0 program, it showed a slight difference in the result. The result of the voltage drop obtained from manual calculation showed that the percentage value of voltage is 1,94%, while the result obtained from ETAP 12.6.0 program showed that the percentage value is 2,01% These results are still in the PLN standard, because it has not exceeded the specified standard that is -10% of its nominal voltage.


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