Bidirectional Hybrid HVDC CB With a Single HV Valve

Abstract

This paper examines two new bidirectional hybrid dc circuit breaker topologies for application in meshed dc grids. The goal is to retain performance of hybrid DC CB with bidirectional current interruption, while reducing semiconductor count, DC CB size and weight. The fault current is routed to the unidirectional internal valve using multiple additional ultrafast disconnectors. Operation of both topologies is studied using a 320 kV, 16 kA simulation model, as well as demonstrated on a 900 V, 500 A lab prototype. The control systems are presented and discussed in detail. The low-voltage hardware prototypes verify performance of several new technical and operating solutions in laboratory conditions. A comparison is made with the existing DC CB topologies and performance and reliability compromises of each topology are assessed. The conclusion is that it might be possible to halve the DC CB semiconductor count while retaining same 2 ms opening speed and bidirectional operation.

Detailed electro‐dynamic model of an ultra‐fast disconnector including the failure mode

“…6 shows a photograph of the 5 kV UFD prototype while Table 1 presents the parameter values for TC and driver. This UFD is an upgrade on the UFD prototypes employed in experimental setups in [10–12] The TC and armature used in this UFD is shown in Fig. 7.…”

“…The benefits are significant since the UFD is much lighter, faster and less expensive than a DC CB. UFDs are further used in many advanced DC CB topologies: four UFDs are employed to remove a semiconductor valve in a bidirectional DC CB in [10], a new method for controlling the voltage between UFD's contacts is shown to reduce fault current in the DC CB by 30% in [11], while in [12], a novel LC DC CB topology based on the fast commutation and controlled UFD voltage is proposed. In traditional bus‐transfer switch applications a similar SF 6 disconnector is utilised [13–15].…”

Interaction characteristics between multi‐port hybrid DC circuit breaker and MVDC distribution system under diversified working conditions

“…A multi‐port hybrid DCCB should be equipped with all the functions of multiple two‐port hybrid DCCBs on a DC bus, so that the reliability and flexibility of power system could be ensured. In other word, it should be capable of interrupting fault current and switching load current through single line or multiple lines concurrently (or not concurrently) [15]. In addition, with direction of load current random and direction of fault current determined, bidirectional load current switching and unidirectional fault current interrupting capability are also needed.…”

“…With advantages of high controllability and relative low operating losses, the hybrid DCCB has attracted wide attention [10][11][12]. Similar with the alternating current circuit breaker (ACCB), the initial hybrid DCCB has two ports, named as two-port DCCB, and consists of a residual current circuit breaker (RCB) in series with three parallel paths that are load current path (LCP), current commutation path (CCP) and energy absorption path (EAP) [13][14][15]. The branch with CCP and EAP in parallel is also named as main-breaker [11,15].…”

“…Similar with the alternating current circuit breaker (ACCB), the initial hybrid DCCB has two ports, named as two-port DCCB, and consists of a residual current circuit breaker (RCB) in series with three parallel paths that are load current path (LCP), current commutation path (CCP) and energy absorption path (EAP) [13][14][15]. The branch with CCP and EAP in parallel is also named as main-breaker [11,15]. To obtain low operating losses, the current is completely conducted by LCP during normal state.…”