34results about How to "Suppress fault current" patented technology

The invention discloses a twisted wire core spiral linear inductor which includes a twisted wire core and an inner sleeve. The twisted wire core is wound in a spiral groove of the inner sleeve. The twisted wire core is formed by spirally twisting a plurality of metal wires and a plurality of aluminum wires. The inner sleeve is in a hollow cylinder shape, the outer wall of the inner sleeve is provided with the spiral groove, the bottom of the spiral groove is provided with a semicircular groove, the radius of the semicircular groove is the same as that of the twisted wire core, and each metal wire is a stainless steel wire or a manganese copper wire. The twisted wire core is formed by spirally twisting the plurality of metal wires and the plurality of aluminum wires. When a capacitor is subjected to internal breakdown, a large current passes through the inductor, the aluminum wires with a low melting point and low yield strength are melted, and stainless steel and the manganese copper wire are high in tensile strength and are still kept intact. The inductor impedance is significantly increased, which is equivalent to absorbing energy of the remaining capacitors to prevent the faultycapacitor from bursting.

The present invention proposes an improved structure of a modular multilevel converter sub-module, including a first switch module and a second switch module connected in series, the negative pole of the first switch module is connected to the positive pole of the second switch module; the first capacitor The positive pole of the first capacitor is connected to the positive pole of the first switching module, the negative pole of the first capacitor is connected to the negative pole of the second switching module; the negative pole of the third switching module is connected to the negative pole of the second switching module, and the third switching module is composed of a current limiting device and a switching device Composed in parallel, the switching device is composed of insulated gate bipolar transistors and diodes connected in antiparallel, and the current limiting device is composed of capacitors and diodes connected in series. The invention is mainly applied to high-voltage and large-capacity modular multilevel converters. When the DC side fails, it can effectively block the DC fault current, better realize fault isolation, and does not need AC circuit breaker action at the same time. . The invention has a simple structure and has fast fault recovery capability after the fault is cleared.

The invention discloses a capacitance type mixing DC breaker for DC power grid and a control method thereof. The breaker topology comprises one mechanical switch, two IGBTs and anti-parallel diodes thereof, two current-limiting inductance and N sub-modules, wherein a first sub-module comprises three capacitance, six thyristors and four diodes; the left (N-1) sub-modules are of the same; each module comprises one capacitance, one thyristor and one diode. The mechanical switch and two IGBTs and the anti-parallel diodes form a current-carrying branch circuit, which is a normal work channel. N sub-modules form a fault current transferring branch circuit, which provides a fault current transferring channel during short circuit. Under normal condition, the system delivers power through the current-carrying branch, and pre-charging is conducted on each sub-module through the control switch. Once faults occur, the breaker can transfer the fault current through the transferring branch circuit,and thereby the zero-voltage turning-off of the mechanical switch can be realized, and at the same time the pre-charging voltage of the capacitance can effectively limit the short circuit current.