Current limiting hybrid DC circuit breaker and current limiting breaking method

Abstract

The invention discloses a current limiting hybrid DC circuit breaker. A current limiting module, a solid switching module and an energy absorbing module are connected in parallel and are then connected in series with a mechanical switching module, the current limiting module and the mechanical switching module are connected in series to carry a normal operating current of a DC system, and the mechanical switching module is used for breaking the normal operating current. A current limiting breaking method is further disclosed. For the same short-circuit fault current, the number of semiconductor devices utilized in the solid switching module can be significantly reduced, when the same solid switching module is utilized, the current limiting breaking capacity of the device can be effectivelyimproved.

Description

technical field [0001] The invention belongs to the technical field of circuit breakers, and in particular relates to a current-limiting hybrid DC circuit breaker and a current-limiting breaking method thereof. Background technique [0002] The rapid development of flexible DC transmission technology has greatly increased its capacity, with higher rated current and smaller line impedance. When a short-circuit fault occurs, the peak value of the short-circuit current is as high as hundreds of kA, and the short-circuit current rises at a higher rate. Traditional power system protection equipment takes a long time to operate and has limited breaking capacity, making it difficult to achieve rapid current-limited breaking of short-circuit currents. If the short-circuit current is not cut off in time, it will cause permanent damage to electrical equipment, so it is urgent to conduct research on new current limiting and breaking technology. [0003] The current DC circuit breakers...

AI Technical Summary

Problems solved by technology

[0004] 1. The high-current arc extinguishing problem of mechanical circuit breakers leads to long insulation recovery time, which makes it difficult to directly break high-current, low breaking reliability and short service life

[0005] 2. The number of power electronic devices used in solid-state circuit breakers is large in series, and the on-state loss is large. Special cooling equipment is required, and the system is complex.

[0006] 3. The liquid metal current limiter can only limit the peak value of the short-circuit current, and does not have the ability to break large currents

[0007] 4. A hybrid circuit breaker composed of a mechanical circuit breaker and a solid-state circuit breaker is used. The arc voltage generated by the mechanical circuit breaker is low when it is switched off, and a multi-stage commutation process is required. The commutation process is long and the control system is complicated; In high-voltage applications, the loop inductance is large, the transfer speed is slow, limited by the level of semiconductors, the breaking capacity is low, or a large number of series and parallel connections are required, which is large in size and high in cost

[0008] In order to ensure reliable breaking of large currents, there are generally backup protection measures such as explosion switches or fuses to prevent system faults from expanding due to commutation failures. However, explosion switches or fuses can only act once, making it difficult to maintain the system and restore it to use immediately.

When the voltage and current levels increase, due to the low arc voltage, large loop inductance, high on-state impedance of the semiconductor switch, and slow current transfer speed, the semiconductor switch cannot be turned off reliably, or multiple devices need to be used Series and parallel connection will greatly increase the volume and cost

[0009] In the existing active current transfer hybrid circuit breaker, the mechanical switch of the main current path is connected in series with a semiconductor switch that can be turned off. Due to the high conduction loss of the semiconductor switch, additional heat dissipation equipment is required, and the control is complicated, so it is not suitable for high current occasion

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