Zusammenfassung. Multiple-Choice-Aufgaben (MCA) sind bei der Leistungsmessung groser Personengruppen besonders okonomisch. Im Zuge des hohen Prufungsaufkommens im Bachelor-Master-System werden MCA-Klausuren auch an deutschen Hochschulen immer haufiger eingesetzt. Doch welche diagnostische Qualitat haben Prufungen mit MCA und wo liegen Vorteile und Probleme? In diesem Literaturuberblick kommen wir zu vier zentralen Ergebnissen: (1) MCA von hoher Qualitat sind in vielen Fallen diagnostisch vergleichbar zu Constructed-Response-Aufgaben. (2) Es existieren effektive Strategien, um Rateeffekten zu begegnen. (3) Der Einfluss des Prufungsformats auf Lern- und Prufungsstrategien ist kaum vermeidbar. (4) Besonders geeignet fur den Hochschulkontext sind die MC-Formate Multiple-Response und Multiple-True-False sowie insbesondere computerbasierte Testaufgaben. Zusatzlich zeigen wir einen Mangel an Forschungsarbeiten auf, die fur belastbare Aussagen uber den diagnostischen Wert von MCA in realen Kontexten unerlasslich ...

Multiple-Choice-Prüfungen an Hochschulen?

Coordination among protective devices in distribution systems is affected by inserting distributed generators. This is attributed to the changes in power flow in addition to the changes of magnitudes and directions of fault currents, which cause mis-coordination between protection devices. This article presents a new protection coordination to overcome the impacts of distributed generator units and to avoid the mis-coordination problem. The proposed protection coordination depends on activating the directional protection feature, which is available in most modern microprocessor-based reclosers. This will be accompanied by updating relays and recloser settings to achieve the correct coordination without extra costs or equipment in the distribution system when equipped with an autorecloser. A real 11-kV feeder, simulated by the ETAP package (ETAP, Irvine, California, USA), is used to prove the effectiveness of the proposed protection coordination. The results ensure the possibility of achieving pro...

Protection Coordination for Distribution Systems in Presence of Distributed Generators

Magnetic pulse compression (MPC) systems are suitable for generating dielectric barrier discharges (DBDs) owing to their capability of producing high-amplitude, short pulse voltage waves. This paper proposes a high-frequency, bipolar magnetic compression system to study DBD plasma characteristics. First, the principle of bipolar MPC is explained [a bipolar MPC system comprises a full bridge inverter circuit, pulse transformer (PT), and magnetic switch (MS)]. Additionally, the design of the PT and MS is described. Then, the waveform of the resistive load is tested and compared with PSpice simulation results. It was found that the nanosecond pulse generator produces a pulse on a resistor with an amplitude of 0–13 kV, a rise time of approximately 100 ns, and a repetition frequency of 0 to several kHz. Finally, this paper studies the plasma characteristics under the application of a high-frequency bipolar pulse, and the charge–voltage Lissajous figure of the discharge waveform is analyzed. Combining discharge photographs and theoretical calculation results yields the relationship between the discharge characteristics and the frequency, which enriches the theoretical study of high-frequency bipolar discharges.

A High-Repetition-Rate Bipolar Nanosecond Pulse Generator for Dielectric Barrier Discharge Based on a Magnetic Pulse Compression System

This paper presents a tool for improving recloser-fuse coordination to enhance distributed generation (DG) installed capacity in electrical distribution systems. The proposed tool could be used to solve recloser-fuse miscoordination problems based on fuse-saving principles. Moreover, it can increase power transfer capability from DG to load by changing the time dial of the recloser and fuse size simultaneously. This tool was developed by writing DIgSILENT Programing Language (DPL) script in DIgSILENT PowerFactory software by considering many conditions such as fault locations, DG types, DG locations and DG sizes. The proposed tool has been implemented in the currently functioning 22 kV Mae Sariang distribution system of the Provincial Electricity Authority of Thailand (PEA). The test results showed that the proposed tool could be used to improve recloser-fuse coordination with a suitable recloser time dial and fuse size, resulting in the maximum capacity of DG connected at any location in the distribution system.

Recloser-fuse coordination tool for distributed generation installed capacity enhancement

This paper presents a new strategy for improving recloser-fuse coordination to enhance distributed generation (DG) installed capacity in medium voltage distribution systems. The proposed algorithm could be used to solve recloser-fuse miscoordination problems based on fuse-saving principles. Moreover, it can increase power transfer capability from DG to load by changing the time dial of the recloser and fuse size simultaneously. This algorithm considers many conditions such as fault locations, DG types, DG locations and DG sizes. The proposed algorithm has been implemented in the practical 22 kV Mae Sariang distribution system of the Provincial Electricity Authority of Thailand (PEA)using DIgSILENT Power Factory software. The test results showed that the proposed method could be used to improve recloser-fuse coordination with a suitable time dial of the recloser and fuse size, resulting in the maximum capacity of DG connected at any location in the distribution system.

Recloser-fuse coordination improvement for distributed generation installed capacity enhancement in electrical distribution systems

Coordination Return of Protective Devices in Distribution Systems in Presence of Distributed Generation

https://cyberleninka.org/article/n/920053.pdf

M. Abroshan

Papers

Coordination Return of Protective Devices in Distribution Systems in Presence of Distributed Generation

Winding Considerations on the High Frequency Transformers