An Efficient Δ-Circuit approach for Online Short-Circuit Calculation in Large Islanded AC Microgrids

In this manuscript, a novel Δ-circuit approach is proposed, which enables the fast calculation of fault currents in large islanded AC microgrids (MGs), supplied by inverter-based distributed generators (IBDGs) with virtual impedance current limiters (VICLs). The concept of virtual impedance for limiting the fault current of IBDGs has gained the interest of research community in the recent years, due to the strong advantages it offers. Moreover, Δ-circuit is an efficient approach, which has been widely applied in the past, for the calculation of short?circuit currents of transmission and distribution networks. However, the traditional Δ-circuit, in its current form, is not applicable in islanded MGs, due to the particular characteristics of such networks, e.g., the absence of a slack bus. To overcome this issue, a novel Δ-circuit approach is proposed in this paper, with the following distinct features: a) precise simulation of islanded MGs, b) fast computational performance, c) generic applicability in all types of faults e.g., single-line, 2-line or 3-line faults, d) simple extension to other DG current limiting modes, e.g., latched limit strategy etc. The proposed approach is validated through the time-domain software of Matlab Simulink, in a 9-bus and 13-bus islanded MG. The computational performance of the proposed fault analysis method is further tested in a modified islanded version of the IEEE 8500-node network.

An Efficient Δ-Circuit approach for Online Short-Circuit Calculation in Large Islanded AC Microgrids

In this manuscript, a novel Δ-circuit approach is proposed, which enables the fast calculation of fault currents in large islanded AC microgrids (MGs), supplied by inverter-based distributed generators (IBDGs) with virtual impedance current limiters (VICLs). The concept of virtual impedance for limiting the fault current of IBDGs has gained the interest of research community in the recent years, due to the strong advantages it offers. Moreover, Δ-circuit is an efficient approach, which has been widely applied in the past, for the calculation of short?circuit currents of transmission and distribution networks. However, the traditional Δ-circuit, in its current form, is not applicable in islanded MGs, due to the particular characteristics of such networks, e.g., the absence of a slack bus. To overcome this issue, a novel Δ-circuit approach is proposed in this paper, with the following distinct features: a) precise simulation of islanded MGs, b) fast computational performance, c) generic applicability in all types of faults e.g., single-line, 2-line or 3-line faults, d) simple extension to other DG current limiting modes, e.g., latched limit strategy etc. The proposed approach is validated through the time-domain software of Matlab Simulink, in a 9-bus and 13-bus islanded MG. The computational performance of the proposed fault analysis method is further tested in a modified islanded version of the IEEE 8500-node network.

Teaching Short - Circuit Calculation with Off - Nominal Turns Ratio Transformers

Teaching short-circuit analysis is conducted primarily through case studies; however, there are not many validated short-circuit studies available on the subject, especially when considering off-nominal turns ratio transformers. In order to improve the teaching of short-circuit analysis, a three phase short-circuit study in an industrial system according to ANSI/IEEE standards by means of Zmatrix method is presented; two case studies are considered: the industrial system with nominal and offnominal turns ratio transformers, in both cases the step by step solution is given in an explicit manner and the analytical results are validated through software simulation.

Study Coordination Design of Over Current Relay on The Kiln Area Electrical System

PT. Semen Padang is one of the largest cement producers in western Indonesia, along with the development of the cement industry PT. Semen Padang added a new Indarung VI factory to support the production process to meet market demand. With the addition of this new factory, a good safety design is needed in the design of the electrical system so that production continuity is not disturbed and reliability values are high. Therefore, over-current protection coordination studies are needed on the electrical system of the kiln area at Trafo 2 Indarung VI PT. Semen Padang to get a safe and reliable system. In the final task, this time will be done modeling, simulation of load flow and short circuit, calculation of relay settings, and simulation of coordination of overcurrent protection phase interference in the electrical system kiln area in Transformer 2 Factory Indarung VI PT. Semen Padang. The plot results of the coordination of the time flow curve obtained through the results of analysis and manual calculations recommended tuning pick-up overcurrent relayand grading time overcurrent relaytuning phase interference. Grading time between overcurrent relay is coordinated by 0.2 seconds. With the protection coordination setting, the electrical system of the kiln area at the Indarung VI factory PT. Semen Padang is safer and more reliable.

Power system protection

This report provides review of importance of power system protection and presents different techniques available in practical situations. The material provided in this report is available online on different resources. Moreover, this report examines different types of faults in power system and discusses the consequences of the faults. Moreover, it also talks about different methods of protection schemes applied for various faults occurred on power system equipment such as transformer, generator, bus, transmission and distribution lines and motors. Furthermore, different relaying techniques are also discussed briefly which are used extensively throughout the report for explaining the importance of these techniques in fault detection and damage prevention. SKM power tool is used for simulation purpose. The simulation result are displayed and explained. Moreover, short circuit calculation and equipment selection method is also discussed in this report.

Power system protection

This report provides review of importance of power system protection and presents different techniques available in practical situations. The material provided in this report is available online on different resources. Moreover, this report examines different types of faults in power system and discusses the consequences of the faults. Moreover, it also talks about different methods of protection schemes applied for various faults occurred on power system equipment such as transformer, generator, bus, transmission and distribution lines and motors. Furthermore, different relaying techniques are also discussed briefly which are used extensively throughout the report for explaining the importance of these techniques in fault detection and damage prevention. SKM power tool is used for simulation purpose. The simulation result are displayed and explained. Moreover, short circuit calculation and equipment selection method is also discussed in this report.

Review on Short-circuit Current Analysis and Suppression Techniques for MMC-HVDC Transmission Systems

The modular multilevel converter (MMC) has been widely adopted in high voltage direct current (HVDC) transmission systems due to its significant advantages. MMC-HVDC is developing towards multi-terminal direct current (MTDC) power grid for reliability enhancement. However, there exist a huge amplitude and a steep rise in fault current due to the low impedances of DC lines and MMCs, which threaten the security and reliability of the DC power grids. It is necessary to restrain the DC short circuit current in order to ensure the safe and stable operation of DC power grids. This paper gives a comprehensive review and evaluation of the proposed DC short-circuit current analysis and suppression techniques used in MMC-based MTDC power girds, in terms of MMC modeling, short circuit calculation, and suppression method. In addition, future trends of countermeasures to short circuit current in MMC-based MTDC power grids are also discussed.