44results about How to "Reduce fault current" patented technology

The invention discloses a bridge arm bypass protection circuit of a modularization multi-level converter aiming at a direct current short circuit fault, and belongs to a converter fault protection device range. The protection circuit is realized by arranging a bridge arm bypass, which is formed by serially connecting a bypass thyristor and a bypass resistor together, between the upper bridge arm and the lower bridge arm of every phase of the modularization multi-level converter. During common function, the bypass thyristor is in an off state, and the bridge arm bypass does not work. After the fault occurs, a sub-module IGBT is locked, and at the same time, the bypass thyristor is conducted, and because of the shunting function of the bridge arm bypass, fault current flowing through sub-module devices is reduced, and attenuation of direct current side current is also accelerated after trip-out of an alternating circuit breaker, and therefore fault recovery time is reduced, and a good fault protection function is provided for the devices and the alternating current system. For a system adopting the direct current circuit breaker, the protection circuit is used to reduce the fault current of the direct current side, and therefore a requirement on the switching-on / off of the current of the direct current circuit breaker is reduced, and economic performance and reliability are improved.

The invention relates to an alternating current side wiring structure of a direct current transmission system of a power supply converter and a control method of the alternating current side wiring structure. The wiring structure comprises an upper stage circuit breaker CB1, an access circuit breaker CB2, a transformer T, a start resistor R and an alternating current circuit breaker CB3, wherein an alternating current incoming line of a converter station is led to a power supply from the upper stage circuit breaker CB1, the upper stage circuit breaker CB1 is connected with the transformer T through the access circuit breaker CB2, the start resistor R and the alternating current circuit breaker CB3 constitute a parallel circuit, and the transformer T is connected with the converter C through the parallel circuit constituted by the start resistor R and the alternating current circuit breaker CB3. When the direct current side of the converter breaks down, control protection is performed to simultaneously send commands for skipping the alternating current incoming line circuit breaker and the circuit breaker connected with the start resistor in parallel. Under the condition that the alternating current incoming line circuit breaker fails, the start resistor is connected into the fault circuit, and thus a fault current flowing through the converter before the skipping of the upper stage circuit breaker is effectively reduced, safety of a converter valve is protected and design parameters of original components of equipment are reduced.

Provided are a multi-level converter having more than one converter arm in which a plurality of sub-modules are connected in series, multi-level converter comprising, a first bypass circuit connected in parallel to at least one sub-module included in more than one converter arm on a first side and including a first switching device, a second bypass circuit connected in parallel to more than one converter arm on a second side and including a diode, a second switching device included in more than one converter arm and having a first end connected in series to at least one sub-module and a second end connected to a first end of first bypass circuit at a single node and a third switching device included in more than one converter arm and having a first end connected in series to at least one sub-module and a second end connected to a first end of second bypass circuit at a single node.

The invention discloses an energy storage charging system, which comprises an AC / DC converter and a DC / DC converter, wherein the high-frequency isolation conversion AC / DC converter takes power from power grid to supply power to a load, and the high-frequency isolation conversion DC / DC converter discharges power from battery to supply power to the load. The energy storage charging system is chargedby converting the charging ACDC into direct current electric energy, and meanwhile, the high-frequency isolated DCDC conversion device can discharge electricity to the load power supply bus, and simultaneously, the ACDC connected with the alternating current converts the alternating current electric energy into direct current electric energy to the load power supply bus to supply power to the load. The charging ACDC is isolated through the high-frequency isolation transformer, and the electric energy passing through a transformer is adjusted, so that the charging voltage and current of the direct-current bus to an energy storage device are adjusted; and a power supply DCDC is isolated through the high-frequency isolation transformer, the electric energy passing through the transformer isadjusted, and the power supply voltage and current of the load power supply bus are adjusted, so that the purpose of charging an electric vehicle or other types of loads is achieved.

The invention provides a feeder automation protection terminal based on an embedded platform, and relates to the technical field of power supply network security and electrical equipment. A DSP chip TMS320F28335 is used as a core processor, and the S232 / RS485 communication is realized by two serial ports on a chip. Ethernet communication is carried out by expanding W5100, and remote control is realized by an I / O pin of the chip through optical isolation control; the remote measurement is realized by a 16-bit high-precision AD chip ADS8556 through bus expansion, and remote signaling is realizedby photoelectric isolation of a bus interface. The invention has the beneficial effects that 1, high-precision data acquisition and calculation of micro signals can be realized; 2, zero sequence power protection of the distribution network; 3, distribution network grounding composite current protection; and 4, an embedded hardware platform with ultra-low power consumption.

The invention discloses a high-frequency isolation conversion energy storage system, which comprises high-frequency isolation conversion two-way DC / DC conversion devices and a direct current bus, wherein a first connecting point of each two-way DC / DC device is connected with an energy storage device; a second connecting point is connected to the direct current bus; through the two-way DC / DC devices, electric energy in the energy storage devices can be subjected to two-way alternating with the direct current bus through high-frequency isolation conversion. A plurality of energy storage devicesare isolated from the high-frequency isolation transformers of the two-way conversion devices subjected to high-frequency isolation from the direct current bus; the electric energy passing through a transformer is limited, so that the fault current of the direct current bus is reduced; the goal of safe protection is achieved; the plurality of groups of energy storage devices are connected with thebus through respectively independent two-way isolation conversion devices; the differences among different energy storage devices cannot generate mutual influence; the energy storage devices with different properties can even be used in a combined way.

The invention relates to a novel quick-response direct-current current limiter and a current limiting method. Through additionally arranging an auxiliary branch circuit to a right iron core column ofa traditional two-column saturated iron core type direct-current current limiter, the negative effect of prolonging the fault current drop time of an original current limiter when a direct-current circuit breaker fails and is broken is eliminated, the breaking process is accelerated, the energy absorption stress of the circuit breaker is reduced, the overvoltage stress is reduced, the response speed is accelerated, and the insulation cost is reduced.

The present invention provides a neutral point grounding device and a control method thereof, wherein the neutral point grounding device comprises: an arc suppression coil, one end of which is connected to the neutral point, and the other end is grounded; a resistance unit connected with the arc suppression coil The parallel connection is used to provide a variable resistance resistance; the controller is used to control the resistance value of the resistance unit and the on-off of the resistance unit circuit. The neutral point grounding device and its control method provided by the present invention have the largest resistance value when the adjustable resistor is initially put into use, and it can be judged that the metallic grounding and medium and low resistance grounding faults of a large proportion of the line are faulty, and the fault current is small, ensuring Personal safety; for a very small number of ground faults with high transition resistance and no fault line is identified, the adjustable resistance is automatically adjusted to the minimum, which further increases the fault characteristics and improves the accuracy of fault selection.

The invention discloses an arc suppression method for a single-phase ground fault of a stator winding of a generator, comprising: if a ground fault of the stator winding is detected, acquiring a reference electromotive force and performing detection, that is, applying a clamping voltage to the reference electromotive force so that the neutral point voltage is adjusted to Clamp the voltage, and then judge whether the voltage value at the stator fault coil is zero, if it is zero, select the voltage at the neutral point of the clamp generator as the optimal clamp voltage; if it is not zero, select another reference electromotive force for detection; where , when selecting the reference electromotive force, follow the same branch to detect and analyze from the first coil backward turn by turn; if the coils on one branch have not been adjusted to 0 after the search and detection of the coils, then analyze the other branch of the same phase until the voltage at the faulty coil is adjusted to 0. Through the invention, the voltage at the fault coil can be adjusted to 0, and the problem of single-phase ground fault arc suppression can be solved.

The invention provides a fault direction judgment method suitable for a wind power access system and belongs to the technical field of power transmission line protection of the wind power access system. The technical problem is that the invention provides a non-earth-fault direction judgment method which is suitable for the wind power access system, and can effectively prevent direction misjudgement caused when a direction element is applied to the wind power side of a link line of the wind power access system. The technical scheme is characterized in that the method comprises the following steps: to begin with, collecting current and voltage at the protection installation place of the wind power side of the link line of the wind power access system; after obtaining the sampling value of a voltage fault component, obtaining positive-sequence component discrete values of the current, voltage and fault voltage; and finally, carrying out judgment on the fault according to the numerical values. The fault direction judgment method is suitable for an electric system.

A grid fault ride-through control device for a flexible direct current transmission system, including a control unit, a detection unit, a switchable braking resistor unit, a power voltage adjustment unit, and a full-bridge braking unit; the switchable braking resistor unit is used for outputting the rectifier terminal A device for first-level power release; power voltage adjustment unit: a device for second-level power release on the output of the switchable braking resistor unit; full-bridge braking unit: used for third-level power release on the output of the inverter terminal Level power release device. The method of the present invention detects the bus voltage on the DC side and the bus voltage on the AC side in real time, and when a fault signal is detected, the DC switching switch is disconnected, the second full-control switch is closed, and the first full-control switch is dynamically turned on to perform dynamic voltage regulation. Realize the maximum release of remaining power. The method can effectively suppress the overvoltage of the direct current bus, avoid the blockage of the equipment of the direct current transmission system, ensure the maximum transmission of the remaining power, and can work normally during the fault period.