実規模配電線雷サージ特性の測定と配電線解析モデルの検証

Simulation analysis is an important method to study the lightning withstand level of distribution lines and conduct the design of line lightning protection. In the process of simulation, the components of the overhead line and the selection of the specific model of lightning current should be taken into account. All the work can be used to get the simulation results which are more consistent with the actual results. Based on the investigating the parameters of oil field lines, insulators and earth resistances, a lightning protection simulation model for typical distribution lines in oil field is built by using ATP-EMTP electromagnetic transient analysis program. By simulation analysis, the influence of line insulation level, earth resistance, layout parameters of arrests and lightning conductor on the lightning withstand level are studied. The results provide a scientific basis for the proposing of the comprehensive lightning protection measures of the distribution lines in oil field.

Arcing horns interrupting fault current is a new type of arcing horns installed on transmission-line towers, which act to interrupt fault current independently within one cycle of commercial frequency. In this paper, we have developed an Electromagnetic Transients Program (EMTP) simulation model of the arcing horns interrupting fault current to ascertain the application effects and devise an installation strategy. The EMTP simulation model can consecutively simulate the entire process, from fault occurrence to fault clearing, by integrating two different kinds of macroscopic arc models, and is capable of dealing with the entire short-circuit current range by taking into account the characteristics of the arc parameters. Finally, we have verified the validity of the EMTP simulation model by comparing simulation and experimental waveforms, and have shown the simulation of current and voltage waveforms in the event of a system fault by using the Japanese Power System Model as an application example of the EMTP simulation model.

Considering electrical network as a continuum has become popular for electromechanical wave analysis. This paper reviews the concept of electromechanical wave propagation. Analysis of large number of generator ring system will be an easy way to illustrate wave propagation. The property of traveling waves is that the maximum and minimum values do not occur at the same time instants and hence the difference between these time delays can be easily calculated. The homogeneous, isotropic 10 generator ring system is modeled using electromagnetic transient simulation programs. The purpose of this study is to investigate the time delays and wave velocities using Power System Computer Aided Design (PSCAD)/Electromagnetic Transient Program (EMTP). The disturbances considered here are generator disconnections and line trips.

Electric energy has been transmiting from power station to end user with transmission and distribution lines.Lightning strokes are problems that occure in transmission and distribution lines and make them fault when theelectric energy were transmited. Surge Diverter or Lightning Arrester has been installing to reduce these faults.In this paper the simulation of lightning stroke and lightning arrester performance on distribution lines 20 kVwere done using EMTP (Electromagnetic Transient Program). Some parameters such us impuls voltage andincreasing voltage on distribution line was inverstigated. As case study in this simulation, Mojosongo 1 mainfeeder 20 kV three phase lines were used.The simulation results show that the lightning stroke 20 kA in By1-61-61E-84-9I on S phase at 0,1 ms, makevoltage on S phase was increased about 1,3054 MV. For R phase and T phase will increase of induced voltagewere 0.79539 MV and 0.80484 MV. We also show the performance of MOV Arrester (Metal Oxide Varistor) inovercoming lightning stroke trouble, where arrester can decrease voltage up to 15.198 kV on S phase, while atR phase and T phase arrester can decrease voltage up to 11.375 kV and 13.616 kV.

The difference between lightning protection and distribution line is analyzed in the paper, which shows that induction lightning protection is the main cause of distribution line. The influence of the heat generated by lightning current and power frequency current on the distribution line is calculated. The results show that the lightning current does not cause the wire breaking, and the continuous power frequency current is the cause of the power distribution line breaking. The simulation model of overhead transmission line in distribution network is established and the induced lightning overvoltage on the line is calculated by simulation. Considering the working conditions of different grounding resistances, the paper calculates and compares the limiting effect of lightning arrester and ground wire on the overvoltage of the circuit. The results show that the lightning arrester has better lightning limiting effect than the two other lightning protection measures. however, the ground resistance needs to be kept low to ensure the lightning arrester is effective.

The paper reports investigation on different parameters of an 11-kV line that affect the lightning impulse failure of a distribution transformer in Pakistan. The equivalent model of the transmission system was developed in ATPDRAW, and the simulations have been carried out in Alternative Transients Program — Electromagnetic Transients Program (ATP-EMTP). The results of the study are used to enhance our understanding about the factors that contribute to distribution transformers' insulation failure which enables us to provide better protection for the distribution transformer and primary distribution (11-kV) lines in Pakistan.

Loop distribution system is increasing by reasons such as requirements for reliability of power supply and increased renewable energy. In the loop distribution system, protection issues such as maloperation of protection relay may arise. This paper proposes the protection scheme based on Internet of Things (IoT) in loop distribution system. The proposed protection scheme uses currents from both distribution lines in the loop distribution system. The difference between both currents in the normal state and the difference between both currents in the fault state are calculated. By comparing these values, the faulted line is determined and the tie switch is controlled. To verify the proposed scheme, the simulations according to fault location and fault resistance are performed using Electromagnetic Transients Program (EMTP). The simulation results show that the faulted line can be accurately judged by proposed scheme and the outage section can be reduced by tie switch control.

Lightning overvoltages in low-voltage circuits in houses originating from a distribution line or an antenna have been actively studied. However, the mechanism by which damage is caused to home appliances due to a lightning strike to the ground near the house is still unclear. This paper discusses lightning overvoltages and currents in low-voltage circuits for various scenarios, such as a lightning strike to the ground, a direct strike to a distribution line, and a direct strike to an antenna. Simulations are carried out using the Electromagnetic Transients Program. From the simulation results, direct lightning strikes cause the most serious damage to home appliances, but nearby lightning strikes should also be considered when designing lightning protection schemes.

A simulation study of a unified power flow controller (UPFC) aimed at examining its capability to operate as a general purpose device for power systems is presented. The simulation is made using the Electro Magnetic Transient Program (EMTP). To utilize the UPFC's possibilities, the three controllable UPFC's parameters have been adjusted during the digital simulation process performed by EMTP. Among different UPFC power circuit structures, the most practical from the viewpoint of efficiency and power device availability based on the concept of multi-pulse inverters is simulated and studied.

This paper presents a new model for the representation of very short transmission lines and cables. This model is an extension for the constant parameter line model in the electromagnetic transient programs such as the EMTP. It overcomes the limitation of using a time step size not larger than the travel time. Unlike the nominal /spl pi/-circuit line model, which is commonly used to represent short lines and cables, the new line model represents the electromagnetic transients more accurately. Simulations have been performed comparing the proposed line model with existing line models, for a case where the new line model provides more accurate results.

In spite of availability of natural sources, still people are now sitting on the dark zone. Because of the remote area, the grid networking system is very weak. As a result of which power stability may not be assured, which greatly effects to the day-today activities of the people in the reason. Fortunately, technology exist that can give the assurance of quality of electricity in an isolated area which is for away from the regular power network. The preset scenario is the coexistence of both AC and DC micro grids, because of the evolutions of different types of loads. The hybrid microgrid concept assume a cluster of different types of loads and distributed generatoroperating as a controllable system which maintain the quality of power and its stability to its local area. To make the world pollution free environment, renewable energy infrastructure is increasing particularly in the distribution network. It has the advantage that the power generated through distributed generation system is utilized in the grid for other users. The PV cell generates voltage at the distribution level. At the end of distribution line a 1 MVA three phase load is connected. In the absence of the generation from the PV cells, the voltages and currents at various lengths of the line are calculated with a single load of three phase 1 MVA. With the inclusion of PV cells, the improvement in voltage dip is also estimated. This estimate provides the power supplied by the PV cell and improvement in voltages. In order to determine the effect of additional load on voltage profile, a three phase load of 1 MVA was connected to intermediate point in the transmission system. This causes the dip in voltage at various nodes of the distribution line. Several combinations of source and loads have been examined to determine the effect on voltage and power. The above work has been carried out using Electro Magnetic Transient Program (EMTP) Software. In order to simulate the system, 8.98 kV, 5 km long line is divided into 5 sections of 1 km each. The sections are represented in the form of Pi-network by its series inductance, resistance and capacitance to ground. Loads are represented by R and L of appropriate magnitude and through EMTP program the calculations are done. The PV cell is represented by a source stepped up to 8.98 kV system. Both single phase and three phase lines have been examined through the above program. The results obtained for various conditions are presented in the paper.

Tower surge impedance is an important parameter in the prediction of HV and EHV lightning outage rates. Several attempts have been made to measure it experimentally on full scale towers, and formulas to calculate this parameter have been proposed by Jordan, Wanger and Sargent, etc. However, the values of surge impedance calculated using these relationships are in poor agreement with each other and, in general, with the various measured values. This paper presents a simulation model of uneven distributing parameter for determining the surge impedance of towers by the Electromagnetic Transients Program (EMTP). This paper also demonstrates that the values so obtained describe the response of the tower adequately when a transmission line is struck by lightning, Furthermore, the simulation value of tower surge impedance is close to the actual test value and the relative error is ten percent.

The interior overvoltage in the extra-high voltage (EHV) power system determines the equipment insulation and safe operation of the system. At first, the paper expounds the problems brought from the application of traditional fixed high voltage shunt reactor to limit the overvoltage in our national EHV power system. Therefore this paper brings forward a proposition to solve these problems by adopting magnetically controlled shunt reactor. This paper mainly introduces a novel type of controlled shunt reactor: Magnetically controlled shunt reactor (MCR). Then its structure and principle of magnetically controlled shunt reactor is presented. The harmonic distribution characteristics, the voltage-current characteristics, control characteristics and response time of MCR are analyzed successively. Afterwards, this paper takes a 500 kV EHV transmission line from Sanyou to Jingzhou for an example, the line model and MCR model are built up. Based on Electromagnetic Transient Program (EMTP), analysis and numerical simulation has been performed to calculate frequency overvoltage and switching overvoltage in the EHV power system with magnetically controlled reactor. (7 pages)

There have been many reports on the computer simulation of lightning striking on overhead power transmission line. This paper, however, describes ground-fault surge voltage on direct-buried EHV cable transmission line, some particular cases of simulation results for viewing what surge could occur and how the surge would propagate in buried power cable when ground fault takes place at a joint. It is considered to know the abnormal voltages or the currents will be useful for designing the insulations of cable line and its protection system. In the computer simulation here, Electromagnetic Transients Program (EMTP) is used and the computation model is constructed based on a real EHV power transmission cable line in commercial operation.

Simulators of the electromagnetic transients program (EMTP) are widely used for the accurate simulation of transients in electric power networks. EMTP simulations are inefficient in representing low-frequency transients whose Fourier spectrum is concentrated on a narrow bandwidth around the carrier frequency of either 50 Hz or 60 Hz as typically found in AC electric power networks. This is because the carrier frequency component is always tracked even if the main interest is concerned with envelope information. Recently it was proposed to modify the EMTP formulation through the introduction of analytic signals and the shift frequency as a novel simulation parameter such that efficient simulation of both high-frequency and low-frequency transients is made possible. The shift frequency allows one to specify by how much the Fourier spectrum associated with the analytic signal is shifted. In the case study presented in this paper, the added value of this technique is illustrated through the simulation of network energization, transitional steady state, and deenergization