A multi-function integrated circuit breaker for DC grid applications

The protection and current flow regulation of highvoltage direct-current (HVDC) grids requires the deployment of additional semiconductor-based equipment including dc circuit breakers (DCCBs) and current flow controllers (CFCs). However, the inclusion of multiple devices could significantly increase the total cost of an HVDC system. To potentially reduce costs, this paper presents an innovative multi-function integrated DCCB (MF-ICB). The proposed device exhibits a reduced number of semiconductor switches and can fully block dc faults at different locations while regulating dc currents. The configuration of the integrated solution and its operating principle are assessed, with its performance being examined in PSCAD/EMTDC using a three-terminal HVDC grid. Simulation results demonstrate the capability and effectiveness of the MF-ICB to regulate grid current and isolate dc faults

A novel HVDC circuit breaker for HVDC application

Hybrid high voltage direct current circuit breakers (DCCBs) are capable of interrupting fault current within a few milliseconds, but this technology has high capital cost, especially in a meshed HVDC grid. To increase the economic competitiveness of hybrid DCCBs, this paper proposes a capacitor commutated dc circuit breaker (CCCB). The CCCB mainly comprises an auxiliary branch with a fast dis-connector in series with semiconductor devices and the main branch with the series connection of a dc capacitor and diode valves. This paper provides a detailed depiction of the CCCB. The topology and operating principles are discussed. The impact of snubber circuits and stray inductances on the commutation process is analyzed. The general sizing method for the main components in the CCCB is detailed. Reclosing to transmission lines with different operating conditions is studied. Several extended topologies are proposed to further reduce the semiconductor cost and on-state operation power loss. The power loss and cost of CCCB are assessed. Extensive simulations on PSCAD/EMTDC verified the dc fault isolation and reclosing of the CCCB

A multi-port current-limiting hybrid DC crcuit breaker

Recently the hybrid multi-port DC circuit breaker (MP-DCCB) is becoming popular in protecting HVDC grids, thanks to their re-duction of power electronics devices. In this paper, an enhanced multi-port current-limiting DCCB (MP-CLCB) for multiple line protection is proposed. The integrated fault current limiter (FCL) inside the MP-CLCB can clear the fault faster with slightly in-creased costs. To reduce the energy dissipation requirement for the surge arresters caused by the newly added current-limiting path, an energy transfer path which provides a loop with the in-ductors during the current decay stage is designed. The theoreti-cal analysis of the pre-charging, current-limiting, fault interrup-tion and energy dissipation of the MP-CLCB is carried out. Moreover, the design principles of the energy dissipation and the key parameters of the MP-CLCB are provided. The proposed approaches are verified through simulations in PSCAD/EMTDC. The results show that the MP-CLCB can replace multiple DCCBs, accelerate the fault current interruption and reduce the energy dissipation requirement for the surge arresters

A low-cost current flow controlling interline hybrid circuit breaker combined with SCR and H-bridge sub-module

A massive number of DC circuit breaker is usually necessary to be installed to protect HVDC grids from DC faults, this will lead to high capital costs because large number of expensive IGBT-in-series are used. In this paper, an interline hybrid circuit breaker is proposed by the combination of SCR string and a small number of H-bridge modules (SCR-IHCB). The proposed SCR-IHCB has the capacity of blocking DC fault of two adjacent lines respectively by sharing only one main breaker branch (MB) mainly composed of low-cost SCR string and H-bridge module instead of IGBT-in-series string. The interline current flow control function is also integrated. Hence it has advantages of simple and compact topology, economical design compared with typical IGBT based HCB solutions. The operation process of the proposed SCR-IHCB is discussed in detail, and the performance is verified by MATLAB Simulink simulation and scale-down prototype experiment

A multi-function integrated circuit breaker for DC grid applications

The protection and current flow regulation of highvoltage direct-current (HVDC) grids requires the deployment of additional semiconductor-based equipment including dc circuit breakers (DCCBs) and current flow controllers (CFCs). However, the inclusion of multiple devices could significantly increase the total cost of an HVDC system. To potentially reduce costs, this paper presents an innovative multi-function integrated DCCB (MF-ICB). The proposed device exhibits a reduced number of semiconductor switches and can fully block dc faults at different locations while regulating dc currents. The configuration of the integrated solution and its operating principle are assessed, with its performance being examined in PSCAD/EMTDC using a three-terminal HVDC grid. Simulation results demonstrate the capability and effectiveness of the MF-ICB to regulate grid current and isolate dc faults

DC busbar protection for HVDC substations incorporating power restoration control based on dyadic sub-band tree structures

In this paper, a new direct current (dc) busbar protection for high voltage dc (HVdc) substations is proposed. The proposed scheme relies on the instantaneous current measurements obtained from the elements (lines and converters) connected to a dc busbar. Such current measurements are analyzed through dyadic sub-band tree structures that are used to extract the specific features, such as polarity, wavelet energy, and wavelet energy ratios. The performance of the scheme is assessed through the transient simulation using the verified PSCAD models. The simulation results revealed that the scheme can: 1) discriminate, effectively and within a very short period of time, between the internal and external faults; 2) detect pole-to-pole and pole-to-ground faults (both solid and highly resistive); 3) switch to healthy busbars (if available) to allow continuous operation; 4) re-energize the converter and restore the power to pre-fault conditions; and 5) remain stable during disturbances and external faults

Coordinated control of DC circuit breakers in multilink HVDC grid

High voltage DC grid is developing towards more terminals and larger transmission capacity, thus the requirements for DC circuit breakers (DCCB) will rise. The conventional methods only use the faulty line DCCB to withstand the fault stress, while this paper presents a coordination method of multiple DCCBs to protect the system. As many adjacent DCCBs are tripped to interrupt the fault current, the fault energy is shared, and the requirement for the faulty line DCCB is reduced. Moreover, the adjacent DCCBs are actively controlled to help system recovery. The primary protection, backup protection, and reclosing logic of multiple DCCB are studied. Simulation confirms that the proposed control reduces the energy dissipation requirement of faulty line DCCB by around 30–42 %, the required current rating for IGBTs is reduced, and the system recovery time reduced by 20–40 ms

Untersuchung von Technologien zur Gleichstromunterbrechung in Hochspannungsapplikationen

Die in dieser Dissertationsschrift dargestellten Zusammenhänge zeichnen ein Bild zu möglichen Technologieansätzen zum Schalten von Fehlerströmen in Hochspannungsgleichstromanwendungen. Dies beinhaltet die Analyse zentraler Schalterkonzepte, sowie Optimierungsansätze zur Steigerung der Abschaltleistung und zur Reduktion des Komponenteneinsatzes. Es wird ein Verfahren zur hochfrequenten Gegenstromeinprägung vorgestellt mit dessen Unterstützung Integrated Gate Commutated Thyristors (IGCT) zur Unterbrechung eines Vielfachen des spezifizierten Abschaltstroms gebracht werden sollen. Dieser Ansatz wird durch eine experimentelle Evaluation überprüft und bestätigt. Weiterhin wird der Sammelschienenschutz als Möglichkeit zum Aufbau eines zentralisierten Knotenschutzes anstelle eines Einzelleitungsschutzes präsentiert

Potential of Bipolar Full-Bridge MMC-HVdc Transmission for Link and Overlay Grid Applications

Bipolare HGÜ Systeme in Multi-Level-Ausführung stellen ein attraktives Lösungskonzept zur Bewältigung einer Vielzahl von Herausforderungen im Kontext heutiger Energiesysteme dar. Da dies jedoch auf Kosten einer deutlich erhöhten Systemkomplexität geschieht, ist ein tiefgreifendes Verständnis des transienten Verhaltens sowie der dynamischen Charakteristik von enormer Wichtigkeit. Diese Doktorarbeit beinhaltet eine detaillierte Analyse von grundlegenden Zusammenhängen bezogen auf bipolare HGÜ Systeme in Multi-Level-Ausführung und stellt ein generisches Regelungs-, Bilanzierungs- und Schutzkonzept vor. Die generelle Leistungsfähigkeit des Konzepts wird durch elektro-magnetische Transientensimulationen nachgewiesen