Hybrid DC circuit breaker based on oscillation circuit
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ORIGINAL ARTICLE
Hybrid DC circuit breaker based on oscillation circuit Yiqi Liu1 · Tian Xia1 · Deqing Li1 Received: 13 May 2020 / Revised: 29 September 2020 / Accepted: 20 October 2020 © The Korean Institute of Power Electronics 2020
Abstract With the rapid development of DC transmission technology, DC circuit breakers, the key equipment for DC fault handling, have become a research hotspot of scholars. This paper proposes a novel hybrid DC circuit breaker topology to improve the shortcomings of traditional hybrid DC circuit breakers. Traditional hybrid DC circuit breakers use too many IGBTs, which results in a large volume and a high cost. The main innovation of this topology is the use of a mechanical switch in series in a solid-state branch, which withstands most of the voltage. An oscillating circuit is in parallel on the mechanical switch, which can generate reverse current to reduce the current flowing through the mechanical switch to zero, to achieve arc free breaking. The feasibility of the proposed topology is verified based on a PSCAD simulation platform. It should serve as a valuable reference for the design of DC distribution systems and DC breakers. Keywords High-voltage direct current (HVDC) · Hybrid DC circuit breaker · Arc free · Oscillation circuit
1 Introduction DC transmission systems have the advantages of low line loss, large transmission capacity, long transmission distance [1]. As a result, they have become a research hotspot. However, there are still many technical difficulties in DC power transmission. Among these difficulties, the design of the DC circuit breaker is the most prominent [2, 3]. As a fast fault isolation device for flexible DC power grids, the DC circuit breaker is the key equipment for constructing a DC power grid. The development of DC circuit breakers is faced with the following technical challenges [4, 5]. (1) DC grid impedance is considerably less than that of AC systems, which causes the short circuit current rise to be substantially faster and at higher values. (2) DC circuits lack natural current zero-crossing. (3) When interrupting fault current, the DC circuit breaker withstands a high overvoltage.
* Yiqi Liu [email protected] 1
School of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin, China
As a result, researchers have carried out a great deal of research on high voltage direct current circuit breakers. According to the differences among the key breaking elements in DC circuit breakers, DC circuit breakers can be divided into three categories [6, 7]: mechanical circuit breakers, solid-state circuit breakers, and hybrid circuit breakers. Mechanical circuit breakers are mainly used in medium voltage power grids, and they have the advantages of relatively simple structures and high reliability. However, they have the following drawbacks: the switch contact is easily damaged by breaking arcs, the breaking capacity is limited, and the removal time of fault current is long, which can easily cause the expansion of accidents and
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