Geomagnetically induced current (GIC) is a ground end manifestation of geomagnetic disturbances (GMDs) and space weather arising from solar activity, which causes half-cycle saturation and represents a potential hazard for a stable and safe operation of earthed high voltage (HV) power transformers. Previous studies have shown that the impact of GIC is not limited to high and mid-latitude regions, but it can also affect power systems located in lower geographic latitudes. This work presents the impact of GIC on HV transformers in the Malaysian power network. A detailed power network was modelled using the Power System Computer-Aided Design for Electromagnetic Transients including Direct Current (PSCAD/EMTDC) software. The entire network was subjected to a geoelectric field strength of 20 V/km at the northward and eastward directions. The GIC analysis has determined the most critical locations in the power network model that are prone to high GICs. The simulation results demonstrated that the most vulnerable substations to GMD events and experience the most severe GICs were those located in the middle of the Malaysian power network. The GIC effects and saturation levels of four transformers' types in these locations have been investigated over the transmission network. Under the GIC condition, transformers were driven into halfcycle saturation and their reactive power consumption drastically increased. Thus, conventional GIC mitigation systems based on neutral blocking devices (NBDs) were proposed and connected to the power transformers to block the GIC flow in their neutral paths. It was found that the GIC protection modes in the mitigation systems effectively eliminate the injected GICs in the neutral paths and are able to prevent the saturation occurrence of the transformers.

For many decades, Geomagnetically Induced Current (GIC) has posed a significant risk over the electrical power grid infrastructures worldwide. The phenomenon occurs due to geomagnetic disturbance (GMD) and related space weather events arising from solar activity. It represents a potential hazard to the secure and safe operation of electrical power grids by causing half-cycle saturation of grounded High Voltage (HV) power transformers, relay misoperation, and increased reactive power demand in the power systems. Previous studies have shown that the occurrence of intense GIC is not limited to high and mid-latitude regions, but powerful space weather events can also result in intense GIC in power systems located in lower geographic latitudes. This study aims to estimate GIC and its impacts on a Malaysian power grid. A network model of the grid was constructed by using the Power System Simulator for Engineering (PSS/E). This represents the first attempt to study GICs in south-eastern Asian power grids since a region is considered to have low GIC risk up to now. During the analysis, firstly, we exposed the entire power network which includes 500 kV, 275 kV, and 132 kV system voltages to different geoelectric field strengths in the 0-180 • directions. The applied geoelectric fields were calculated based on benchmark value for 1 in 100 years of GMD events. Then we disconnected the 132 kV low voltage systems from the network model to investigate their influence on the calculated GICs. The results demonstrated that the most vulnerable substations to GMD events and experienced large GICs were those located in the middle of the Malaysian power network. The maximum GIC was recorded at substation 22 with the value of 44.58 A due to the peak electric field of 1.2 V/km at 100 • field direction. Also, the results showed that the calculated GICs slightly increased when 132 kV systems were removed from the power network, especially at the substations directly connected to these systems.INDEX TERMS Geomagnetically induced current, geomagnetic disturbances, space weather, energy, high voltage transformers, Malaysian power system.

Geomagnetic disturbance (GMD) arises during space weather and solar activity can result in geomagnetically induced current (GIC) flow in the grounded power transformers in the power network. This GIC may cause half-cycle saturation of transformers and lead to severe damage or blackout. To block the GIC flow into the power transformers, the neutral blocking devices (NBDs) based on capacitor banks are often installed in the neutral ground paths of transformers to mitigate the GIC. However, the high voltage (HV) can build up across these capacitors during ground faults and may cause a ferroresonance phenomenon in the power network. This phenomenon generates high voltages/currents in the transformer windings and results in transformer failure. This work investigates the effect of connected NBDs to the power transformers on the potential power network ferroresonance in Peninsular Malaysia. The complete analysis was carried out using the Power System Computer-Aided Design for Electromagnetic Transients including Direct Current (PSCAD/EMTDC) software. These transformers were selected in the power network due to the sensitivity of their locations to GMD events. The NBD systems were tested under different working conditions. The simulation results found that the metal oxide varistors (MOVs) arresters in NBDs fault protection mode effectively clamped ferroresonance overvoltages below the protection level under faulty conditions. Also, the results showed that GIC protection modes with 1 Ω and 3180 μF in the mitigation systems had the lowest ferroresonance overvoltages in the neutrals of the transformers under faulty conditions. Based on the results, the recommendations were provided to the local power utility which will help to improve the reliability of the power supply to the consumers.

This study has been carried out to test two hypotheses; whether a small metal object such as mobile phones in possession of a human body increases the chances of a direct lightning strike and whether a similar object increases the chances of a side flash. Simulations were done in COMSOL Multiphysics for a metal sphere of radius 10 mm placed at the head level of a 2 m tall human being. A five-meter-tall cylindrical lightning target of resistivity 2.75 GX m and 10 nX m were considered. The influence of the side flash increases with the size of the metal object and also as its shape deviates from the spherical dimension. The outcomes of the study confidently discard the possibility of a metal object of practically viable size on a human body to influence the direct lightning attachment process. A metal sphere of radius about 22 m or a person of height 8.5 m is required for increasing the possibility of such a direct strike. Thus, the popular public concept is firmly rejected. However, the same metal object may significantly increase the side flash probability if the victim is close to the lightning struck object or inside an unsafe shelter.

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Geomagnetically induced current (GIC) has become a significant concern that can affect the electrical power grid by causing a half-cycle saturation of power transformers. This saturation leads to an increase in even and odd harmonic distortions and reactive power losses of transformers, which may consequence in improperly triggering relays, tripping reactive power (VAR) compensators and shunt capacitor banks. Also, these reactive losses, harmonic, and the stray flux resulted due to this saturation may lead to overheating windings and cores of power transformers and generators and hence blackout. In this paper, GIC analysis has been conducted on a modified IEEE-18 bus test system by using Power System Simulator for Engineering (PSS/E) and Power System Computer-Aided (PSCAD/EMTDC) software. The simulation results have been obtained by considering a worst-case scenario of geomagnetic disturbance (GMD) by applying uniform induced electric fields with values of 10 V/km and 20 V/km at different directions with and without GIC blocking devices. Also, the impact of grounding resistances of the substations on calculated GIC due same mentioned induced fields has been investigated. The results show that the highest total reactive power losses across the system are obtained due to related induced electric fields at 120° and 300° storm angle. After the connection of GIC blocking devices to the substations, these reactive losses have drastically reduced. In addition, simulation results of the same test system by using PSCAD platform are obtained to investigate hysteresis and harmonic results during system operation and the presence of GIC.

Geo magnetically induced currents (GICs) can cause saturation of the magnetic core of transformers in a power system. This saturation can conduce to generating harmonic currents, voltage-control problems and overheating of the transformer internal components, leading to gas relay alarm/operation and possible damage. In this work, GICs effects have been analyzed on hybrid PV-wind system transformers. The system implemented through using Power System Computer Aided Design (PSCAD/EMTDC) platform and made up of 2.1 MW wind farm, 2 MW solar photovoltaic (PV) farm, power storage system and load. Then the system is integrated with 33 kV grids through a 480V AC bus and step-up wye/delta transformer. In addition, Pi-section has been used between different parts of the system. The GIC is modeled as a controlled DC voltage source and inserted into the system through a neutral point of a wind turbine (WT) transformer. The simulation results of reactive power, voltage and current waveforms, and non-linear behavior due to asymmetric saturation of the magnetic core in the transformer due to 100 A GIC current injections are obtained. Moreover, different GIC blocking devices have been applied to mitigate or eliminate the flow of GIC to the system.

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