Zero volt switching hybrid DC circuit breakers

Circuit breakers for High Voltage Direct Current (HVDC) are seen as a required technological step in the development of HVDC grids. The development of several new HVDC circuit breaker prototypes indicate that this step may be achieved in the years to come. In order to facilitate the installation of HVDC circuit breakers, appropriate standards and tests need to be developed. These tests and standards must ensure that the technology is capable of functioning as required. In cases where direct testing cannot be carried out, a synthetic test circuit is used to recreate the conditions of the power system. Voltage testing envelopes are used to define the specification of these synthetic test circuits for Alternating Current (AC) circuit breakers. A similar concept can be applied to fault currents in HVDC networks, allowing specifications for HVDC synthetics test circuits to be defined. Testing envelopes which encapsulate the fault currents are analytically shown in this paper and compared to detailed simulations of faults in a VSC HVDC system. Testing envelopes can be drawn for a range of converter topologies in point-to-point and multi-terminal applications. Taking into account the large power electronic elements in the recently developed HVDC circuit breakers, discussion is given to the definition the worst case fault for a HVDC protection system. This paper demonstrates that a terminal fault is not necessarily the worst fault scenario for HVDC circuit breaker.

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“…Many proposed DC circuit breaker designs contain large power electronic switches in them, such as [1,2,[7][8][9][10][11].…”

Section: Power Losses In Semiconductor Breakermentioning

confidence: 99%

Fault Current Testing Envelopes for VSC HVDC Circuit Breakers

Cwikowski

Chang

Barnes

et al. 2015

11th IET International Conference on AC and DC Power Transmission

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“…Hybrid circuit breakers based on a zero voltage switching principle [19] were composed of power electronic devices in parallel, which acted as a non-contact switch and a mechanical switch. The switching losses are less than that in completely solid state breakers, but the mechanical circuit breakers limit the action time.…”

Section: Hybrid DC Breakersmentioning

confidence: 99%

Research on fast solid state DC breaker based on a natural current zero-crossing point

Xiang

Hua

Wen

et al. 2014

J. Mod. Power Syst. Clean Energy

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The DC fault characteristics of voltage source converter based high voltage direct current (VSC-HVDC) systems are analyzed in this paper. The phenomenon whereby the capacitor on DC side discharges quickly during a DC fault contributes to a large short-circuit fault current. Neither traditional DC breakers nor DC switches can cut off the fault current under this condition. A fast solid state DC breaker design method is proposed in this paper. This method is based on the fault current characteristics of the inverter in multi-terminal HVDC systems (MTDC), where a fault current appears at the natural zerocrossing point near the inverter. At this point, by coordinating the AC breakers near the rectifier, the DC breaker could reliably cut off the DC fault current and protect the system. A detailed model for this fast solid state DC breaker and its operation sequence are studied, based on this design method. Simulations modeling a five-terminal meshed DC grid and a fast DC breaker were carried out with PSCAD/EMTDC using this design method. The results from the simulations confirmed the validity of the design method.

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“…According to this principle, a hybrid circuit breaker based on high-speed switch (HSS) and parallel connected capacitor is designed to commutate the fault current, which has been introduced a lot before. [6][7][8][9] These breakers have independent branches to carry the rated current and break fault current. As the current is commutated into the capacitor in single-stage operation during the fault current breaking, the energy stored in inductance is absorbed by the capacitor within a very short time.…”

Section: Introductionmentioning

confidence: 99%

Research on a novel two-stage direct current hybrid circuit breaker

Rong

et al. 2014

Review of Scientific Instruments

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The DC hybrid circuit breaker based on high-speed switch (HSS) and parallel connected capacitor has been widely applied in the fault current breaking of DC system. However, when the current is commutated from HSS to the capacitor according to single-stage operation, the capacitor has to absorb a large amount of energy stored in the system inductance within very short time. Meanwhile, a high over-voltage rate of rise is especially prone to be produced between the contacts of HSS, which will lead to a failed breaking. As a result, a novel DC hybrid circuit breaker based on the two-stage operation is proposed and analyzed in this paper. By controlling the thyristors in the commutation branches, the fault current is fast commutated into the capacitor, which can not only realize the arcless open of HSS, but also decrease the over-voltage rate of rise significantly in comparison to the traditional single-stage operation. The simulation model of fault current breaking under different conditions in 10 kV medium voltage DC system is constructed. The simulated over-voltages of single-stage and two-stage operations in the case of fault current breaking are compared and analyzed. Finally, the fault current breaking test in the two-stage operation is investigated experimentally, which validates the feasibility and effectiveness of the simulation model well.

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Zero volt switching hybrid DC circuit breakers

Cited by 47 publications

References 4 publications

Fault Current Testing Envelopes for VSC HVDC Circuit Breakers

Fault Current Testing Envelopes for VSC HVDC Circuit Breakers

Research on fast solid state DC breaker based on a natural current zero-crossing point

Research on a novel two-stage direct current hybrid circuit breaker

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