A three-dimensional direct lightning strike model for lightning protection of the substation

Externally gapped line arrester performance in high voltage transmission line using frequency grounding system: Absorbed energy and expected life assessment

Power System Transients

The roof arrester of electric multiple units (EMU) can efficiently limit the overvoltage, and ensure the safe operation of the EMU electrical equipment. In the process of high-speed operation, the traction power supply system is often affected by overvoltage. In addition, roof arrester explosion accidents occasionally occur. In this paper, the on-line voltage measurement system of the EMU arrester is developed. By analysing a large number of voltage waveforms, the abnormal voltage is divided into three categories: over-phase voltage, high harmonic voltage and steep impulse overvoltage. The characteristics of abnormal voltage waveforms are then summarised. The electrothermal coupling simulation model of the arrester is developed, and the current response and temperature distribution of the arrester under abnormal voltage are calculated. The impact of the impulse voltage energy on the arrester temperature is studied by applying a triangular wave voltage to the model. Finally, some suggestions are proposed for the operation and maintenance of the roof arrester. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1049/hve2.12196

Study on operation voltage monitoring and electrothermal coupling simulation of electric multiple unit (EMU) roof arrester

A surge arrester is modeled as a simplified electrical circuit in power frequency applied voltage that consists of a capacitance branch in parallel with a nonlinear resistor. Under applied harmonic voltage, the obtained resistive current of the simplified model exhibits some deficiency, especially in its harmonic contents. This paper presents a harmonic model for metal-oxide surge arresters that can be utilized to simulate their performances under applied harmonic voltage. It has three parallel RC branches to simulate fundamental, third and fifth harmonics contents of total leakage current. Proposed and conventional models have been simulated under different applied harmonic voltages to show the capability of the proposed model. Also, real voltage and leakage current signals, which have been measured experimentally from a 20 kV metal-oxide surge arrester, have been compared with simulation results. Results show that the proposed model can simulate the performance of metal-oxide surge arresters more accurately than the conventional ones under applied harmonic voltages.

Modeling of Gapless MOSA at Low Current Region Considering Harmonic Content of Operating Voltage

Lightning strokes on overhead transmission lines cause overvoltage surges, which propagate along the power line in the form of traveling waves. These overvoltages endangered the reliability of overhead transmission line and substation equipment. Lightning overvoltages are one of the most important factors in designing of substation and overhead lines insulation. This paper presents various lightning overvoltages in real electrical substation 220 kV due to shielding failure of overhead transmission line based on model study with ATP-EMTP software.

Lightning overvoltages in electrical substation 220 kv due to shielding failure of overhead transmission line

Line surge arrester (LSA) application is widely known and used for solution of the power system transient. They are used for improving lightning performance of overhead lines (lightning protection, bad tower grounding conditions), increasing insulation level, reducing clearances, compacting lines or saving overhead line ground wire. One of the types of line arresters is the externally gapped line arrester also known as EGLA. Model studies for proving their effectiveness is preferred due to expensive live tests. Approaches for modeling externally gapped line arresters through ATP-EMTP software is simulated in the paper. The models are tested with several lightning waves and different approaches are compared each other. The presented models could be implemented into case studies with EGLA applications.

Modeling approaches for externally gapped line arrester through ATP-EMTP model study

One of the main reasons for power system faults and outages are lightning overvoltages. Mitigation the outages and overvoltage magnitudes are challenge for every power system. Externally gapped line arresters improve overhead line reliability. Their efficiency depends on many factors as configuration of the arresters, grounding resistance, area of mounting and others. They need to withstand the energy stress under lightning conditions. In order to check the energy stress this paper present model study of externally gapped line arresters for various case studies like direct lightning strike and backflashover conditions. Studies are performed with ATP-EMTP software. The obtained results can be useful for determination of energy capability and case studies for EGLA applications.

Energy stress of externally gapped line arresters for various cases through model study

Power system is exposed to overvoltages due to different reasons. Switching overvoltages are one of common causes of outages and damages in the system. Switching overvoltages are caused by circuit breaker operations. These operations are classified as closing and reclosing. Overhead line energization and de-energization causes switching surges. These surges under certain conditions can be dangerous for the facilities in the power substations. Therefore the knowledge of overvoltage levels and the factors affecting them is important for power system reliability. In this paper switching overvoltages due to closing and re-closing operations of overhead power line 220 kV are investigated through model study. ATP-EMTP software is used for power system modeling. Case studies without using surge arresters and with surge arresters are reviewed in the paper. Overvoltages in different location on overhead line are shown.

Switching transients in overhead transmission line 220 kV

The requirements for modern power systems are directly related to the need for continuous power supply to consumers while meeting the requirements for electricity quality. Planned and unplanned outages occur in the system, they directly affecting the normal operation and maintenance of the equipment in the system. This determines the need to study the processes and regime parameters in case of failures in the system. Due to the specific characteristics of the power system, model research in a software environment is preferred way for investigations for power system transients. The paper focus on parameters change in case of single-phase faults in the 220 kV electrical network depending on the place of failure and the operation of the relay protection. The investigation was performed through model study in the ATP-EMTP software environment.

Overvoltages under single-phase fault conditions in the high voltage grids

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