51results about How to "Lower insulation level" patented technology

The controllable arrester in metal oxide includes control part and fixed part connected in series. In normal operation of system, the control part and the fixed part together bear system voltage. When amplitude value of system over voltage exceeds prearranged threshold value, the fixed part bears system over voltage. Combining power electronic device in large power with arrester in metal oxide (MO), the invention puts forward concept and designing idea of controllable arrester for aiming at issue of over voltage protection for transmission system in super voltage, extra high voltage. Based on condition of maintaining invariable performance parameters of MO resistance piece, the invention reduces residual voltage of arrester effectively by using characteristics: quick response speed of power electronic device, steady operation, and flexible adjustment so as to raise protection level for arrester.

The invention provides a direct drive permanent magnet wind generator, a direct drive permanent magnet wind generator system and a stator of the direct drive permanent magnet wind generator. The stator comprises a stator support, a stator iron core arranged on the peripheral wall of the stator support, and a paddle side tooth support, wherein the paddle side tooth support is arranged on the paddle side axial end face of the stator iron core, at least one air hole is formed in the peripheral wall of the stator support, and at least one second air hole is formed in the paddle side tooth support. The stator further comprises at least one air flow passageway used for communicating the first air holes with the second air holes, wherein the air flow passageways penetrate through the stator iron core. The micro-positive pressure technology is used in the stator and a rotor of the airborne wind turbine, and therefore a motor can dry itself in a self-adaption mode, external severe air flow is prevented from entering the motor, the service life of permanent magnet poles is prolonged, the insulation level reduction of devices inside the motor is prevented, the risk that the motor is corroded by severe air flow is lowered, and the insulation reliability is improved.

The invention provides a permanent magnet direct-drive wind-powered generator, system and stator thereof. The stator comprises a stator bracket, a stator iron core, a propeller side gear pressing plate and a propeller side enclosing plate; the propeller side gear pressing plate is arranged on the axial end surface of propeller side of the stator iron core; a first air hole is formed in the peripheral wall of the stator bracket; a second air hole is formed in the propeller side gear pressing plate; the stator further comprises an air channel for communicating the first air hole with the second air hole; the air channel passes through the inner part of the stator iron core; a comb teeth air feeding hole is formed in the propeller side enclosing plate and is connected with the second air hole through an air guide tube; a first spiral comb teeth structure is annular in the whole appearance and is communicated with the comb teeth air feeding hole is arranged on the propeller side enclosing plate; first spiral comb teeth are positioned in annular gaps formed by the propeller side enclosing plate and a rotor sealing ring. According to the technical scheme, the rotor has the advantage that the multi-phase airflow sealing can be performed for the annular gap between the propeller side enclosing plate and the rotor sealing ring.

The invention relates to an overvoltage protection method and overvoltage protection devices of modular multi-level converters. The overvoltage protection method comprises the following steps of arranging the overvoltage protection devices of the modular multi-level converters between alternating current ends of the modular multi-level converters and the ground, or between direct current ends and the ground, or between the alternating current ends, or between the direct current ends or more than one of the positions at the same time, setting operation voltage parameters of lightning arresters, setting operation voltages of discharging circuits and setting delay operation time of the discharging circuits, wherein each overvoltage protection device comprises the discharging circuit, a voltage-sharing damping circuit and the lightning arrester, the operation voltage parameters of the lightning arresters comprise reference voltages, operation overvoltage protection levels, lightning overvoltage protection levels and steep wave overvoltage protection levels, and the operation voltages of the discharging circuits are set according to expected invasion power frequency overvoltage levels. By means of the overvoltage protection method and the overvoltage protection devices of the modular multi-level converters, economical efficiency and reliability of the modular multi-level converters are improved.

The invention provides a voltage transformer excitation characteristic test system. The voltage transformer excitation characteristic test system includes a power frequency voltage source (1) and a direct current source (2) which is connected in series with the power frequency voltage source (1). According to the voltage transformer excitation characteristic test system of the invention, the power frequency voltage source and the direct current source which are in serial connection are simultaneously applied to the primary side of a tested voltage transformer, so that the direct current source is at a low electric level, and therefore, the voltage level of the direct current source can be decreased, and test requirements can be satisfied, and thus, the influence of the direct current source on the excitation characteristics of the voltage transformer can be authentically simulated based on the superimposed power frequency voltage source and direct current source; and based on the superimposition of the power frequency voltage source and the direct current source, the voltage transformer excitation characteristic test system is small in size, and therefore, production cost can be reduced.

The invention discloses a grounding isolation device based on a low-frequency power transmission system, and the device comprises a first AC power grid which is disposed on an island; the second alternating-current power grid is arranged on the coast; the power transmission cable is used for establishing connection between the first alternating-current power grid and the second alternating-currentpower grid; the grounding isolation device is arranged between the first alternating-current power grid and the second alternating-current power grid; the input end of the AC/AC frequency conversiondevice is connected with the grounding isolation device through a power transmission cable, the output end of the AC/AC frequency conversion device is connected with the second AC power grid and usedfor converting the first frequency three-phase voltage of the first AC power grid into the second frequency three-phase voltage, and the first frequency is smaller than the second frequency. By arranging the grounding isolation device, the overvoltage phenomenon of the low-frequency power transmission system in the power transmission process can be reduced; therefore, the insulation level of the grounding isolation device of the low-frequency power transmission system is reduced, the safety of low-frequency power transmission of the low-frequency power transmission system is ensured, and zero-sequence current generated by asymmetric faults can be isolated through the reasonable wiring mode of the grounding isolation device.

The invention discloses a phase selection switch controller which comprises an upper machine communication module, a main control module, a signal processing and collecting module, a charging and discharging control module of an energy storing capacitor and a safety interlocking module. The main control module is mainly composed of a DSP system, an external RAM and a man-machine interface. The signal processing and collecting module is composed of an analog signal conditioning unit, a logic control unit and a digit collecting unit. The charging and discharging control module of the energy storing capacitor is composed of an AC/DC high-frequency switch power supply, a discharging and energy storing capacitor C, a protective diode and a photoelectric coupler. The phase selection switch controller has the advantages that during closing and opening of the capacitor, inrush currents are reduced, overvoltage is hindered, a series reactor is not needed, the overhauling period and the service life of a high-voltage switch are prolonged, re-ignition and re-strike are prevented and the insulating level of equipment is lowered. When fault currents are cut off, the cut-off capability is improved, abrasion of the switch is reduced, stability of the system is improved and the service life of the switch is prolonged.

The invention discloses a controllable lightning arrester and a method and a system for reducing operating overvoltage, and aims to provide improvement measures for the residual voltage problem of the lightning arrester, replace the lightning arrester in a direct current circuit breaker with the controllable lightning arrester, and dynamically change the volt-ampere characteristic of the lightning arrester, thereby reducing the residual voltage of the lightning arrester in the direct current circuit breaker. The controllable lightning arrester is composed of a lightning arrester body and a controllable switch, wherein the lightning arrester body is composed of a controlled element and a fixed element. The controlled element and the fixed element are connected in series, and the controllable switch is connected to two ends of the controlled element in parallel. The direct-current circuit breaker formed by the controllable lightning arrester is applied to a flexible direct-current power distribution network, the insulation level of a system can be reduced, and the reliability of the system is improved. Therefore, the technical problems that in the prior art, the insulation level of a system is required to be high, and the reliability of the system is poor are solved.

The invention provides an electric ice melting system and an ice melting method thereof. The electric ice melting system comprises a first blocking device, a second blocking device, a first Zigzag winding, a second Zigzag winding, and a direct current ice melting device, wherein the first blocking device and the second blocking device are respectively connected in series on a return line between two main transformer bus bars; a positive pole of the direct current ice melting device is connected to an input side of the second Zigzag winding, and output sides of the second Zigzag winding are respectively connected to three-phase electric wires on one side of the return line; a negative pole of the direct current ice melting device is connected to an output side of the first Zigzag winding, and input sides of the first Zigzag winding are respectively connected to three-phase electric wires on the other side of the return line. The electric ice melting system can melt ice with electricity,and there is no need to power off and queue up to melt ice. The direct current ice melting device has much applicability and is easy to promote and use, and the current is not limited in size, and the access device occupies a small area and has low cost.

The invention discloses a test device for excitation characteristic of a voltage transformer, and aims to provide the test device, capable of improving test accuracy, for the excitation characteristicof the voltage transformer. The test device comprises a power frequency voltage source and a DC current source, wherein the power frequency voltage source comprises a power frequency voltage source front-stage switch, a power frequency voltage source voltage regulator, a power frequency voltage source post-stage switch, a power frequency transformer, an AC loop capacitor, an AC loop resistor, a protection device, a power frequency voltage divider high-voltage arm capacitor, a power frequency voltage divider low-voltage arm capacitor, a power input voltmeter, a power frequency transformer primary voltmeter, a power frequency voltage divider voltmeter and a transformer primary ammeter, the power frequency voltage source front-stage switch is arranged at a primary side of the power frequencyvoltage source voltage regulator, the power frequency voltage source post-stage switch is arranged at a secondary side of the power frequency voltage source voltage regulator, a primary side of the power frequency transformer is connected with the secondary side of the power frequency voltage source voltage regulator, and one end of the power frequency voltage divider high-voltage arm capacitor is connected with an A terminal of a secondary side of the power frequency transformer.

The invention relates to the technical field of a self coupling transformer, in particular to a constant-magnetic-flux voltage regulating structure for an ultrahigh-voltage self coupling electric transformer. The constant-magnetic-flux voltage regulating structure comprises a main transformer body and a voltage regulating transformer body, wherein the main transformer body comprises a serial connection winding, a public winding and a third winding, the voltage regulating transformer body comprises a voltage regulating winding and an exciting winding, the voltage regulating winding and the exciting winding sleeve the same iron core, the serial connection winding and the voltage regulating winding are connected in series and are then connected in series with the public winding, the main transformer device body is also provided with an exciting voltage regulating winding, the exciting voltage regulating winding, the serial connection winding and the public winding sleeve the same iron core, the exciting voltage regulating winding and the exciting winding are connected in parallel, and the exciting voltage regulating winding is provided with a voltage regulating switch. The self coupling transformer adopting the constant-magnetic-flux voltage regulating structure provided by the invention can realize the connection between two ultrahigh-voltage electric networks; a constant-magnetic-flux voltage regulating mode is adopted, so the third winding voltage fluctuation and the iron core overexcitation cannot be caused; meanwhile, the insulation level of the voltage regulating winding is reduced, and the manufacturing difficulty and the cost of a tap switch are reduced.

The invention discloses a multi-port direct-current power supply. The multi-port direct-current power supply comprises a multi-winding transformer and a power unit. The multi-winding transformer internally comprises a 10kV input winding and 27 groups of 380V output windings, the output windings are connected with the alternating-current input end of the power unit, and the direct-current output end of the power unit is divided into 750V output and 825V output; a multi-port flexible combination method is provided to realize multi-direct-current voltage level power supply ports, the ports are multiple, the voltage levels are multiple, the multiplexing functions are multiple, and the power supply is suitable for various types of working conditions and test occasions; a multi-winding transformer technology is mature, and the technical difficulty of direct connection of the power units can be greatly reduced; and the structure, the size and the device specification of the power unit can adopt a unified model, and all the power units adopt the same design so that mutual replacement and maintenance are facilitated. By means of the combined control mode of a direct current side, voltages of all ports can exist at the same time, the insulation level of a low-voltage side X winding, a low-voltage side Y winding and a low-voltage side Z winding of the multi-winding transformer is reduced, and the purpose of reducing the size and the cost of the multi-winding transformer is achieved.

The invention provides a dynamic energy release device and equipment and a DC power supply system. The dynamic energy release device comprises at least two dynamic energy release modules which are connected in series between a DC power transmission line and a first ground wire. A first switch is arranged between the input end of the dynamic energy release modules and the DC power transmission lineand/or the first switch is arranged between the grounding end of the dynamic energy release modules and the first ground wire. A second ground wire is connected between the at least two series connected dynamic energy release modules. The first switch is disconnected in case of fault elimination of continuous phase change failure of the DC power transmission system so that the dynamic energy release device can be quickly cut off, the problem of slow system recovery caused by capacitance charging in the recovery process of the DC power supply system can be avoided, and the system is enabled toquickly recover normal operation. The second ground wire is arranged between the series connected dynamic energy release modules so that the system insulation level can be effectively reduced.