Energy Storage for DC Grids - Circuit Breakers

Abstract

Disclosed is an energy storage breaker for a direct current power grid. The energy storage breaker for the direct current power grid is composed of a modular parallel power regulation circuit, a modular current limiting circuit and an energy storage inductor. Under a normal work state, the modular parallel power regulation circuit achieves energy storage and release functions for the direct current power grid by charging and discharging the energy storage inductor or a voltage source type energy storage device, and can effectively restrain power fluctuation of the direct current power grid. Under a fault state, when a current of the direct current power grid is larger than a current of the energy storage inductor, the energy storage inductor is connected into the direct current power grid in series through the modular current limiting circuit, and limits an excess current of the direct current power grid, and simultaneously a modular power regulation system discharges the energy storage inductor until the current of the energy storage inductor is reduced to 0. After the current of the direct current power grid is reduced to 0, a switch connected into the direct current power grid in series is opened, and therefore the function of achieving zero current interrupt for the direct current power grid under fault is achieved.

Description

technical field [0001] The invention relates to an energy storage-circuit breaker for a DC power grid. Background technique [0002] High-voltage direct current transmission has the characteristics of low line cost, high active power, and fast adjustment speed, and has been widely used in various fields of industrial production. In order to ensure that the HVDC system can work reliably, it is necessary to provide a DC circuit breaker for the HVDC grid. In the AC system, the zero-crossing point of the AC current can be used to realize the current shutdown; while in the DC current, since there is no zero-crossing point, the switching off of the DC current is far more difficult than that of the AC current. At the same time, since the DC power grid is often used to transmit the output power of new energy power generation, due to the instability of new energy power generation itself, there are large fluctuations in the output power of the DC transmission line. On the one hand, ...

AI Technical Summary

Problems solved by technology

On the basis of the conventional AC mechanical circuit breaker, the mechanical scheme artificially creates a zero-crossing point similar to that in the AC system to break the circuit by adding an auxiliary circuit. This scheme has a long breaking time and a limited life, and cannot meet the needs of the DC power grid. ; while the existing high-power semiconductor device solutions, such as figure 1 The Chinese patent CN103997322A "A full-solid-state DC circuit breaker and its control method" and figure 2 The shown Chinese patent CN104184108A "DC circuit breaker and its control method" all adopts the method of directly shutting off the power electronic device to cut off the DC current

Due to the existence of line inductance, when the power electronic device is turned off, a high voltage will be induced across the power electronic device, which will adversely affect the safety of the power electronic device

At the same time, these two methods only provide the function of breaking the circuit, and cannot stabilize the power fluctuation of the DC grid

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