Impact of Geomagnetically Induced Currents on High Voltage Transformers in Malaysian Power Network and Its Mitigation

Abstract

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.

Research on the Influence of Urban Subway on Neutral Current of High-Voltage Substations Along the Line Under Complex Environment

“…In Figure 2, r is the equivalent resistance per unit length of the OCS, Rr is the equivalent resistance of the rail, RG is the equivalent resistance per unit length of the ground grid, RE is the equivalent resistance per unit length of the earth, Rg1 is the equivalent transition resistance between the rail and the ground grid, Rg2 is the equivalent transition resistance between the ground grid and the earth, IL1 and IL2 are the supply current from the equivalent power source at both ends, L1 and L2 are the distance between the train and the both ends, Itr is the traction current of the train, which can be presented in (6).…”

“…Compared with the transformer bias caused by the grounding pole of the high voltage direct current (HVDC) transmission and the geomagnetically induced current (GIC) [6], the stray current generated by the rail transit operation changes more rapidly, the polarity reversal is more frequent, and it also has more cyclical [7]. In [8], a novel suppression method for grounding transformer against earth current from urban rail transit is proposed, which is superior to the traditional methods in improving the total harmonic distortion (THD).…”

Effect of GIC Neutral Blocking Devices (NBDs) on Power Network Ferroresonance in Malaysia

“…In the previous work, we tested the GIC protection mode in the connected NBD systems under an extreme geomagnetic storm scenario with the value of 20 V/km. The capacitor banks in the NBDs successfully could block the induced GICs in the neutral paths of four types of HV power transformers, as presented in Table 1 [30]. In this study, NBD systems were tested under the faulty condition to investigate the impacts of the GIC protection mode in the system on the potential power network ferroresonance and the effectiveness of the fault protection mode in suppressing the resonance overvoltages.…”

“…These transformer types have been selected from the power network due to the sensitivity of their locations to GMD events. The connected NBDs could successfully block the injected GICs in the neutral paths of transformers [30]. In this work, these NBD systems will be tested under the faulty condition to investigate their impacts on the potential power network ferroresonance.…”

Geomagnetically Induced Current Analysis in Malaysian Power Transmission System

“…In addition, the review of earlier studies has shown that the GMD impacts are not limited to power grids in high and mid-latitudes but also extend to high voltage (HV) power grids at lower geographic latitudes [17]. In the previous work, we applied an extreme geomagnetic storm scenario on the modelled Malaysian power network and investigated the saturation effects of four HV power transformers and the effectiveness of the connected GIC mitigation systems to block GICs [18]. Therefore, this research aims to predict and investigate the effects of GMD on a Malaysian power grid, using geoelectric field magnitudes for low-latitude countries like Malaysia with consideration of the local geomagnetic latitude and earth conductivity structure with and without lower voltage system network.…”