112 results about "Crowbar" patented technology

The invention discloses a double-fed wind power generation system with a low voltage ride through function. The double-fed wind power generation system can effectively protect a double-fed wind power converter when the voltage of a power grid dips (including three-phase symmetrical short-circuit faults and asymmetrical short-circuit faults of the power grid), simultaneously can reversely send reactive power or active power to the power grid so as to support removal of power grid faults, and continuous running of a double-fed wind driven generator is guaranteed. The double-fed wind power generation low voltage ride through device comprises an active crowbar device and a direct current link chopper device. The active crowbar device is used for protection of rotor overcurrent and overvoltage when the voltage of the power grid dips, effectively avoids impact of the rotor overcurrent and overvoltage on a machine side converter, simultaneously can be quickly disconnected after fault impact is over so as to recover normal control of the double-fed wind power converter, and avoids off-grid running of a whole machine set during the fault ride through period. The direct current link chopper device is used for protection of direct current link overvoltage when power grid faults occur or power grid control is abnormal. When the power grid faults occur, energy of a generator rotor is fed back to direct current link so that direct current link overvoltage occurs, the effective value of the direct current link chopper device reduces direct current link voltage overshoot, and the safety of a converter power unit is guaranteed.

The invention provides a method and device for controlling uninterruptible operation of a wind generator system in case of faulted power grid voltage. An existing doubly-fed motor rotor-side frequency converter and a CROWBAR circuit are utilized to realize the uninterruptible operation of a DFIG (doubly-fed induction generator) wind generator system when the power grid generates the serious voltage faults. The method at least comprises the following steps: 1) detecting the voltage of the power grid; 2) triggering CROWBAR protection; 3) waiting a voltage of the power grid to recover; 4) cutting off the CROWBAR protection; 5) starting a grid-side current transformer; and 6) starting a motor-side current transformer. In the invention, motor time sequences of corresponding states of the current transformer are given when the power grid voltage is seriously asymmetrical and when the motor is in a non-voltage state; the CROWBAR protection circuit of the current transformer is used to finishthe protection for the wind generator system and the current transformer; and the method and device provided by the invention are suitable for various faults of the power grid such as a symmetric voltage fault of the power grid, an asymmetric fault of a small voltage value of the power grid, a seriously asymmetric voltage fault of the power grid and a non-voltage fault of the power grid, and meets grid-connected requirements of the wind generator system formulated by a power grid corporation. Mechanical installation of equipment is simple and the installation is convenient and quick.

The invention discloses a method and a device for protecting a wind generating set during electric network voltage dip in a short time. A crowbar circuit with low voltage ride through is set in a wind generating system and comprises at least one set of main thyristors and an auxiliary circuit which consists of an auxiliary thyristor, a capacitor and a reactor; and the main thyristors and the auxiliary circuit realize the switching-on and switching-off of the crowbar circuit together. When the crowbar circuit needs to be switched on, the main thyristors are triggered to enable the circuit to be switched on; and when the crowbar circuit needs to be switched off, the auxiliary thyristor is triggered, and the auxiliary capacitor and the auxiliary reactor work together to realize the switching-off of the main thyristors which are previously switched on. The switching-off loop of the thyristor which consists of the auxiliary thyristor, the auxiliary capacitor and the auxiliary reactor is used; and when the circuit needs to be switched off, the auxiliary thyristor is triggered so as to realize the switching-off of the thyristor which are previously switched on.

The invention discloses a low-voltage ride through control method and a low-voltage ride through control device for a doubly-fed wind power generating system. The device comprises a reversible power converter, a motor controller, a signal detection circuit and a crowbar protection circuit. The crowbar protection circuit consists of a three-phase uncontrolled bridge rectifier, a primary release circuit and a secondary release circuit. When a power grid has a low-voltage failure, the reversible power converter stops working, the primary and secondary release circuits in the crowbar protection circuit are switched on at the same time and work in parallel to rapidly release transient impact current in a rotor winding of a doubly-fed motor; when the current of a rotor attenuated to a rated value, the secondary release circuit stops working, and the primary release circuit is still switched on to release the transient current in the rotor wining; and after the low-voltage failure of the power grid is eliminated to recover the voltage of the power grid, the reversible power converter restarts working, and the crowbar protection circuit completely stops working. By the method and the device, high ride through capability and good effects are ensured, the time of a transient process for low-voltage ride through can be shortened, the voltage recovery of the power grid can be accelerated and secondary over-current can be effectively prevented.

The invention discloses a low-voltage ride-through switch and dynamic resistor for a double-fed type wind driven generator set, comprising the double-fed type wind driven generator set, wherein a rotor and a rotor current transformer of the double-fed type wind driven generator set are connected; meanwhile, the rotor is further connected with a crowbar resistor in parallel and a stator is directly connected with a power grid, so that a low-voltage ride-through control topological structure of the crowbar resistor is formed; and a rotor winding and a stator winding of the double-fed type wind driven generator set are respectively and additionally provided with three switches and three dynamic resistors. According to the invention, the feasibility of control effects of a protection system can be guaranteed and the voltage grade of the rotor current transformer is not improved, so that the cost of the system is saved.

A three-phase disconnect switch for a power distribution system that supplies three-phase power from a source through a main circuit breaker to multiple three-phase feeder circuits, includes three pairs of contacts adapted for connection to the three phase lines of a selected one of the feeder circuits for opening and closing each of the phase lines, and a movable actuator associated with the three pairs of contacts and responsive to a signal indicating the occurrence of an arcing fault in the selected feeder circuit for initially creating a short circuit across the three phase lines of the feeder circuit and then opening the contacts.

The invention discloses a fault detection method for a circuit sent out from a wind power plant. The method comprises the following steps: 1 collecting phase current of a circuit sent out from a current wind power plant after a fault appears; 2 building a linear relationship between measurement by using the least squares fitting method, and estimating the frequency of the phase current; 3 when the calculated frequency of the phase current is in a normal frequency range, judging that a crowbar protection circuit is not started, and entering the step 4; or else, judging that the crowbar protection circuit is started, and returning to the step 1; 4, finding out the position of sending out the fault in the circuit through a distance protection element. The fault detection method can be immune to non-power frequency current characteristics sent out from a double-fed wind power plant; the operation characteristics of fault impedance and distance protection can be quickly calculated aiming at various fault types; the protection reliability and selectivity are greatly improved.

The invention relates to a doubly-fed converter with a reliable low-voltage ride-through capacity, and the doubly-fed converter consists of a rapid synchronization switch GK, a direct-current unload unit DBU, a stator Crowbar, an auxiliary power supply rapid switching unit APS, a network-side power module GSC, a rotor-side power module RSC, a synchronization circuit breaker K1, a controller KZQ and the like. The doubly-fed converter is provided with a port A, a port B, a port C and a port D, wherein the port A is connected with a stator of a doubly-fed wind power generator, the port B is connected with an electric network, the port C is connected with a rotor of a doubly-fed generator, and the port D is connected with a main control system power supply of a doubly-fed power generating unit; a terminal AC of the stator Crowbar is connected with a stator of the doubly-fed generator, and the direct-current unload unit is connected with a common direct-current bus of the GSC and the RSC; and the working status of each part of the doubly-fed converter is respectively controlled by a signal transmitted by the controller KZQ.

A switch crowbar circuit comprises a main contact, and accessory circuits are connected between the first electrode end and the second electrode end of the main contact in parallel. The switch crowbar circuit is characterized in that the accessory circuits comprise accessory contacts, current-limiting resistors and a three-end controllable circuit including a first voltage end, a second voltage end and a control end; the first voltage end is connected with the first electrode end, the second voltage end is connected with the second electrode end, the control end is connected with the first end of the accessory contact, and the second end of the accessory contact is connected with the first voltage end through a current-limiting resistor; when a forward voltage is supplied between the first voltage end and the second voltage end and the control end receives trigger signals, the controllable circuit is conducted; when a backward voltage is supplied between the first voltage end and the second voltage end and the control end receives trigger signals, the controllable circuit is conducted; when a forward or backward voltage is supplied between the first voltage end and the second voltage end and the control end has not trigger signals, the controllable circuit is cut off. Compared with the existing technology, the invention uses a three-port controllable circuit with control end to receive trigger signals to conduct electricity while the accessory contacts are closed so that the working current flows from the controllable circuit, thereby damaging the arcing conditions of main contact, efficiently eliminating the voltaic arc when the main contact is closed; the circuit structure is simple, the installation and use are convenient, the arc-suppressing effect is good, and the invention is propitious to generally wide application.

The invention provides a zero-voltage ride-through control method for a doubly-fed wind generator, and the method comprises the following steps: determining a resistance range of a dynamic active Crowbar hardware protection circuit and performing graded input so as to limit rotor side overcurrent, absorb excess energy and protect a rotor side converter; accelerating the attenuation of a stator flux linkage by improving a flux linkage active attenuation control strategy, so the problem that a double-fed fan is out of control for a long time due to repeated input of a protection circuit is avoided; the DC voltage conversion rate is reduced by improving a grid-side converter control strategy, and the DC bus voltage rapidly tends to be stable when a severe fault occurs; the power captured by awind wheel is reduced to a greater extent within the same time by improving the variable pitch strategy of the doubly-fed wind generator, so the risk of galloping caused by rotor rotating speed risedue to energy imbalance of a fan is reduced; and DStatcom reactive power compensation is added to help to quickly recover the system voltage after the fault. According to the method, the zero-voltageride-through capacity of the doubly-fed wind generator is improved through a comprehensive control method formed through the synergistic effect of the five strategies, and the safe and stable operation of a wind power system is guaranteed and maintained.

The invention discloses a multi-scale low-ride-through matching method for reducing the switching times of a doubly-fed wind generator crowbar. Firstly, the grid-connected point voltage of the doubly-fed wind generator is monitored in real time, and whether the current of a rotor is to be out of limit or not is estimated, so as to determine the switching time of a control strategy; then, in the control link of a rotor side converter, a low-voltage ride-through control strategy for comprehensively considering time scale and current scale is switched, wherein the strategy strictly meets the requirements of wind power grid-connected specifications, and is characterized in that the combination of de-excitation control and crowbar protection is carried out; finally, a space vector control strategy is timely switched back according to the recovery condition of the grid-connected point voltage, or the wind generator is removed. By adoption of the method, the low-voltage ride-through capability of the doubly-fed wind generator can be effectively improved, the number of switching times of the crowbar is reduced, and the wind generator is prevented from absorbing a large amount of reactive power from the system during use of the crowbar, thereby playing important practical significance for guaranteeing the voltage stability of the power system.

The invention provides a double-fed fan symmetric fault active support control method based on a transient controllable domain. The method comprises the following steps: calculating a change condition of an intermediate parameter along with a rotating speed according to a double-fed fan unit parameter; selecting an alternating current equivalent resistance value of the hardware protection device; measuring the end voltage of the doubly-fed fan, performing voltage coordinate conversion, and calculating a rotor current DR component; according to the rotor current DR component obtained through calculation, calculating a transient controllable domain in combination with RSC maximum transient current limitation; under the condition that the transient controllable domain exists after the fault, according to the transient controllable domain obtained through calculation, carrying out amplitude limiting on the rotor current reference value; and under the condition that the transient controllable domain does not exist, predicating the controllable domain after Crowbar excision to determine the Crowbar excision moment, so as to avoid repeated triggering. According to the invention, the safety of the DFIG and the continuity of power grid support are ensured, and the stability of the end voltage of the DFIG is ensured.

The invention relates to the technical field of sliding plate replacement devices, and discloses a sliding plate replacement device for converter sliding plate slag blocking. The sliding plate replacement device for converter sliding plate slag blocking comprises a base plate, universal wheels are fixedly installed at the bottom of the base plate, and a placing rack is fixedly installed at the topof the base plate. A placing slot is formed in the top of the placing rack, a cushion plate is movably installed inside the placing slot, supporting columns are fixedly arranged at the position, located on the left side and the right side of the placing rack, of the top of the base plate, and a pull rod is fixedly arranged on the right side of the base plate. According to the sliding plate replacement device for converter sliding plate slag blocking, an second electric push rod drives a supporting seat and a clamp to slide on a guide rail through a sliding block, so that the clamp exerts an external force on the sliding plate, the sliding plate is more convenient to replace, collision and scratch caused by prying by a crowbar during installation and disassembling of the sliding plate areavoided, the effect of simple and convenient replacement is achieved, the practicality of the replacement device s improved, and the replacement device is convenient to promote.

The present application discloses methods, circuits and systems for power conversion, using a universal multiport architecture. When a transient appears on the power input (which can be, for example, polyphase AC), the input and output switches are opened, and a crowbar switch shunts the inductance which is used for energy transfer. This prevents this inductance from creating an overvoltage when it is disconnected from outside lines.

The invention discloses a converter, a safety protection method thereof and a hard crowbar circuit. The method is applied to a control unit of the converter. The hard crowbar circuit is connected between a positive direct-current bus and a negative direct-current bus of the converter; the hard crowbar circuit comprises a choking coil and N crowbar units which are connected in series, and the hard crowbar circuit and a middle backflow supporting capacitor in the converter form an energy absorption loop; and each crowbar unit comprises a controllable switching device of which the control end is connected with the control unit. The safety protection method comprises the following steps: receiving a state detection signal for the converter; judging whether an IGBT single tube failure fault or a bridge arm cut-through fault occurs in the converter according to the state detection signal; if yes, sending a starting signal to each controllable switching device in the hard crowbar circuit, so that safety protection is carried out on the converter based on the energy absorption loop; and if not, maintaining the turn-off state of each controllable switching device. Safety protection can be carried out on the converter in time, and further deterioration of faults and influence on other elements are avoided.

The invention discloses a doubly-fed wind turbine generator high-voltage ride through control system and a working method thereof, and belongs to the technical field of wind power generation. A Crowbar circuit is connected between the rotor of a doubly-fed wind generator and the machine side of a converter, and an unloading circuit is arranged on a direct current bus between the machine side and the grid side of the converter; and the converter, the Crowbar circuit and the unloading circuit are respectively connected with the converter controller, and the converter controller is connected to amain control system of the doubly-fed wind turbine generator. Through the converter, the converter controller, the Crowbar circuit and the unloading circuit, the problems of overvoltage, overcurrent,direct current bus voltage rise and the like in the voltage rise transient process can be solved when the doubly-fed wind turbine generator generates high-voltage ride-through, so that the generatoris safe, stable and free of off-grid in the high-voltage ride through period, and normal operation and power generation of the wind turbine generator are ensured. The system is reasonable in design, easy to construct and low in hardware requirement, the stability and safety of the system are guaranteed, and good economic benefits are achieved.

The invention provides a composite fault ride-through control method and device, equipment and a storage medium, and relates to the technical field of doubly-fed wind turbine generators. Uncontrollability caused by a rotor side converter bypass can be avoided, reactive power support is provided for a unit to the maximum extent, and the reliability of high voltage ride through is improved. The method comprises the following steps: switching the rotor side converter of a doubly-fed wind turbine generator to an overcurrent suppression mode to operate under the condition that the voltage of a power grid is greater than a preset threshold value, so as to reduce the impact on the doubly-fed wind turbine generator by suppressing the rotor overcurrent and reduce the input frequency of a crowbar circuit; and under the condition that the power grid voltage is larger than a preset threshold value, switching the grid side converter of the doubly-fed wind turbine generator set to operate in an outer loop power grid voltage control mode, and adding a feed-forward compensation item to voltage outer loop control of the grid-side converter, so as to keep the voltage of a direct-current bus stable under the condition that the power grid voltage suddenly rises and carry out reactive power support on the power grid to promote rapid voltage recovery.

A method for operating a multi-level bridge power converter of an electrical power system connected to a power grid includes receiving, via a controller of the power converter, an indication of a transient event occurring in the power grid or the electrical power system. The power converter has a plurality of switching devices arranged in an active neutral point clamped topology. Accordingly, upon receiving the indication, the method includes activating a crowbar algorithm programmed in the controller of the power converter to bifurcate a current received by the power converter into a plurality of different current paths defined by the plurality of switching devices.

The invention discloses a portable crowbar device which is simple in structure, low in cost, convenient to adjust and convenient to carry. The device comprises a base, a limiting plate, a fixed shaft,a sliding block, a sleeve rod, a fixed block, a push rod motor, a limiting rod, a baffle and a pull ring. A placing groove is formed in a top of the base; the fixed block is fixed to a side wall of the bottom of the placing groove; a top of the fixed block is rotationally connected with the push rod motor through the fixed shaft; the sleeve rod is arranged in the placing groove; the sleeve rod isrotationally connected with the base through the fixed shaft; a sliding groove is formed in the bottom of the sleeve rod; the sliding block is slidingly connected into the sliding groove; and an output shaft end part of the push rod motor is rotatingly connected to the bottom of the sliding block through a hinge. According to the portable crowbar device, through the arrangement of the limiting rod and a limiting groove, the length between the sliding rod and the sleeve rod is changed, an object does work well, the time is saved, meanwhile, through the arrangement of the push rod motor, the stability of the device is improved, and the working efficiency is improved.