3630 results about "High-voltage direct current" patented technology

A system for controlling an electrosurgical generator using a full bridge topology is disclosed. The system includes a high voltage direct current power source which supplies power and a radio frequency output stage which receives power from the high voltage direct current power source and outputs radio frequency energy at a predetermined radio frequency set point. The system also includes one or more sensors which determine one or more parameters of radio frequency energy being applied to tissue and a microprocessor configured to receive one or more parameters and outputs the predetermined radio frequency set point to the radio frequency output stage as a function of one or more of the parameters of radio frequency energy.

High voltage direct current systems to connect direct current energy sources to an alternating current system. In one aspect, a system includes a plurality of direct current modules having variable direct current inputs; an inverter; and a direct current bus to connect the direct current modules to the inverter, where the bus is configured to operate at a nominal voltage higher than 100 volts and to operate within 10 percent of the nominal operating voltage.

A modular HVDC converter system including a high voltage direct current network, and at least two DC/AC converters being connected in series to the HVDC network. Each of the DC/AC converters is arranged to provide AC to a separate AC load.

A system to collect energy from generation systems such as, for example, wind farms or solar farms with distributed energy-generation equipment. The energy is collected and transmitted to a feed-in site. At the feed-in site, static inverters alone or in combination with pulse width modulation inverters may be used to feed the energy to a power grid. In some other cases, back-to-back static inverters create a high-voltage direct current to feed a transmission line.

The invention relates to a breaker of a direct current system, in particular to a semi-controlled active injection current high voltage direct current breaker and a realization method thereof. The breaker comprises a high speed switch-thyristor module branch, as well as a lightning arrester branch and a bridge circuit which are connected in parallel with the branch, wherein a capacitor-reactor series branch and a resistor-thyristor series branch are connected in parallel and then connected with middle points of two bridge arms of the bridge circuit; and the two ends of a capacitor are connected in parallel with a charging loop. The breaker is based on a direct current breaking principle by the traditional active injection current manner; semi-controlled power electronic devices are added; a high speed mechanical switch is adopted; the advantage of low loss during normal breakover is kept; and bidirectional current can be broken quickly without an arc. The breaker is simple in circuit topological structure, simple and convenient to control, mature in technology, easy to realize, great in current breaking capability, high in withstand voltage level and strong in expansion capability, and the cost is lowered greatly since the number of the adopted power electronic devices is small.

A high-voltage direct-current breaker is composed of an initial current path (1) and a fail current interdicting path (2). The initial current path (1) comprises at least one electric electronic switch module (3) and a mechanical switch (4), and the fail current interdicting path (2) comprises an initial capacitor (C) and a modular switching subunit series connection component (5). The modular switching subunit series connection component (5) is formed by connecting a plurality of sub units (6) in series. When a high-voltage direct-current electric transmission line fails, the opening and closing of a fail electric transmission line can be rapidly achieved.

The invention provides a device, a system and a method for measuring space charges by using an electro-acoustic (PEA) method. The device comprises a first electrode, a second electrode, a first thermostatic source, a second thermostatic source, a high-voltage direct current power supply, a pulse generator and a piezoelectric transducer, wherein the first electrode is used for contacting with one surface of the tested insulation material sample; the second electrode is used for contacting with the other surface of the tested insulation material sample; the first thermostatic source is used forconducting the temperature to the first electrode; the second thermostatic source is used for conducting the temperature to the second electrode; the high-voltage direct current power supply is used for transmitting the high-voltage direct current to the first electrode; the pulse generator is used for transmitting a high-voltage pulse signal to the first electrode; the piezoelectric transducer is used for detecting the acoustic signal of the tested insulation material sample, generated by the functions of the temperature gradient field, the high-voltage electric field and the high-voltage electric pulse, and is used for converting the acoustic signal into an electrical signal to output. The invention is used for measuring the distribution of the space charges in the high-voltage direct current power equipment insulation in the temperature gradient field.

A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

The invention relates to high-voltage DC cable insulating material and a preparation method thereof in the technical field of the insulating material. The preparation method is that: 100 weight portions of low-density polyethylene, 0.1-1 weight portion of anti-oxidizer, 0.5-5 weight portions of nano inorganic powder and 0.2-5 weight portions of maleic anhydride are placed into and mixed and compounded in a banbury mixer; the temperature of mixing and compounding is 373K to 378K and the mixing and compounding time is 10 to 15 minutes; 0.1-5 weight portions of cross-linking agent is added into the mixture and is mixed and compounded under the temperature of 373K to 378K for 10 to 15 minutes; then, the high-voltage DC cable insulating material is obtained; wherein, the density of the low-density polyethylene is less than 0.9g/cm<3>. The insulating material of the preparation method can effectively improve the mechanical and electric properties of the high-voltage DC cable, thus avoiding the disadvantage that the environment is polluted and damaged by an oilpaper insulating cable due to the leakage of the insulating oil.

A high voltage direct current (HVDC) converter system includes a line commutated converter (LCC) configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in only one direction. The HVDC converter system also includes a buck converter configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in one of two directions. The LCC and the buck converter are coupled in parallel to an AC conduit and are coupled in series to a DC conduit. The HVDC converter system further includes a filtering device coupled in parallel to the buck converter through the AC conduit. The filtering device is configured to inject AC current having at least one harmonic frequency into the AC conduit.

A high voltage direct current (HVDC) converter system includes at least one line commutated converter (LCC) and at least one current controlled converter (CCC). The at least one LCC and the at least one CCC are coupled in parallel to at least one alternating current (AC) conduit and are coupled in series to at least one direct current (DC) conduit. The at least one LCC is configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in only one direction. The at least one current controlled converter (CCC) is configured to convert a plurality of AC voltages and currents to a regulated DC voltage of one of positive and negative polarity and a DC current transmitted in one of two directions.

The invention relates to a circuit breaker and a realization method thereof, and specifically relates to a mixed high-voltage direct-current circuit breaker and a realization method thereof. The direct-current circuit breaker is based on the principle of secondary current transfer. A main branch is composed of a quick-action mechanical switch and a current transfer module which contains a full-controlled device, which ensures the advantages of low loss and flexible current transfer control in the state of normal conduction. A first current transfer branch is composed of half-controlled device thyristors connected in series, so that the circuit breaker has strong fault flow capacity and breaking capacity, 'zero voltage and zero current' of the mechanical switch can be maintained long enough, and arc-free switching of the mechanical switch is realized. A second current transfer branch is composed of capacitors with pre-charged voltage, an inductor, and series-connected thyristors. After the thyristors of the first current transfer branch are reliably switched off, the capacitors quickly build up direct voltage high enough to resist the system, and an energy absorption circuit limits the voltage of the capacitors. Thus, the size and cost of the capacitors are well controlled.

An apparatus for DC fast charging of an electric vehicle includes an active front end AC-DC converter and an isolated DC-DC converter. The active front end AC-DC converter is adapted to rectify a medium voltage alternating current (AC) from a utility grid to a high voltage direct current (DC). The isolated DC-DC converter is adapted to transform the high voltage DC to a low voltage DC for charging the electric vehicle.

The present invention relates to a no-ozone cleanable electrostatic dust collector which comprises an ionized region, a dust collecting region, a high-voltage alternating current power supply and a high-voltage direct current power supply. The ionized region is arranged above the dust collecting region; the high-voltage alternating current power supply is connected with the ionized region; the high-voltage direct current power supply is connected with the dust collecting region; adjacent ionized electrode plates are two different electrodes; dust collecting electrode plates are fixed on an outer frame by the block position; and the interphase dust collecting electrode plates are connected by conductive material, so that the adjacent dust collecting electrode plates are two different electrodes. The no-ozone cleanable electrostatic dust collector can collect dust efficiently, no ozone nearly is produced, no static electricity is accumulated, thus being safe and environment protective and having wide application range.

The invention discloses a method for determining the commutation failure of a high voltage direct current system, which comprises the following steps: S1 calculating the load component and the fault additional component of commutation voltage on a conversion bus of the high voltage direct current system when a fault occurs in a certain point thereof under a given fault close angle; S2 determining an integral interval and calculating the actual commutation voltage time area; S3 comparing the actual commutation voltage time area with the critical commutation voltage time area and determining whether the fault of the point can cause the commutation failure or not; S4 repeating the step S1 to step S3 and determining an alternating current fault region which causes the commutation failure of the high voltage direct current system. The invention further discloses a device for determining the commutation failure of the high voltage direct current system, which comprises a preparing unit, a calculation unit and a determining unit. The method and the device can greatly reduce the calculation scale, lead the precision to meet the needs of engineering applications, disclose the mechanism of how the fault close angle affects the commutation failure and be applicable to the analysis of fault steady state and fault transient state.

A hybrid green uninterruptible power system including an input port, a boost module, a secondary battery, a bi-directional converter module, and an inverter module is provided. The boost module converts an AC utility power into a high voltage DC power. The bi-directional converter module includes a multi-winding transformer for either converting the high-voltage DC power into a low-voltage DC power for charging the secondary battery, or for releasing and boosting the power stored in the secondary battery. The multi-winding transformer further induces an additional DC power when converting the power. Whereby, the hybrid green uninterruptible power system is able to generate the additional DC power all the time and optimizes its energy converting efficiency between the secondary battery and an external device consuming DC power.

The invention belongs to the technical field of electrostatic spinning and relates to a portable handheld electrostatic spinning device. The top of a pushing rod of a medical syringe is provided with a pressure welding switch, a metal foil is arranged on the top side fixedly, a spinning solution is arranged in a front end inner cavity of the medical syringe, a square battery and a high-voltage direct-current inverter are arranged fixedly on the side wall of the syringe in a butt joint mode, and a stainless steel needle head which is used for spinning is arranged at the bottom end of the syringe in an inserting mode. A conventional medical syringe needle head structure and the syringe are combined and matched, the spinning solution is stored in the inner cavity of the medical syringe which is provided with the stainless steel needle head, the square battery provides a power supply for the high-voltage direct-current inverter, when the direct current voltage is inverted, the voltage in the unit of kilovolt, the positive pole of the high-voltage direct-current inverter is communicated electrically with the stainless steel needle head, and the negative pole of the high-voltage direct-current inverter is communicated electrically with the metal foils. The device is simple in overall structure, is convenient to carry, use and operate, applicable to occasions such as outdoor teaching and wounded rescue and high in economical value.

The invention provides a biological mass thermal decomposition, gasification and purification method which comprises, disintegrating the biological mass, gasifying in a furnace, obtaining retort gas, cyclone dedusting, cooling down and purifying, high voltage static coke trapping, making the coke tar bubbles and dust in the coal gas deposit onto the coke collection poles, thus purifying the coal gas, finally washing and dewatering.

The invention discloses a direct current de-icing device based on a full-bridge modular multilevel converter. The full-bridge modular multilevel converter has a three-phase bridge structure, each phase of the converter comprises an upper bridge arm and a lower bridge arm, the upper and lower bridge arms which are respectively formed by serially connecting N full-bridge power modules end to end, and the full-bridge power modules form a chain type multilevel structure, the front ends of the first power modules of the upper bridge arms of all phases are connected to form the positive pole of a public direct current bus; the tail ends of the Nth power modules of all lower bridge arms of all phases are connected to form the negative pole of the public direct current bus; the tail ends of the Nth power modules of all upper bridge arms are connected with the front ends of the first power modules of the respective lower bridge arms of the phases by smoothing reactors; and the center of the electric reactor serves as the alternating current bus of the phase. The device has high high-voltage direct current output capacity and the direct current voltage of the device can be regulated continuously from zero; on the other hand, the fully compatible chain type scalable vector graphics (SVG) topology can realize quick dynamic reactive regulation; and the device has the combined functions of direct current de-icing and alternating current dynamic reactive compensation.

The invention relates to a high-voltage direct-current direct-current (HVDC-DC) power electronic converter transformer comprising a cascade modular converter (1), a double-winding medium or high-frequency transformer (2) and a fully-controlled H bridge (3). The cascade modular converter (1) consists of two same bridge arms, and the two bridge arms are formed by connecting the same number of sub-modules end to end in a cascading way; the middle points of both the two bridge arms are respectively connected with two leads of the primary side of the double-winding medium or high-frequency transformer (2); and the secondary side of the double-winding medium or high-frequency transformer (2) is directly connected with the fully-controlled H bridge (3) or is connected in series with a resonant capacitor (5) between the double-winding medium or high-frequency transformer (2) and the fully-controlled H bridge (3). The HVDC-DC power electronic converter transformer can realize the conversion of the high-voltage DC voltage and the low-voltage DC voltage and has the electrical isolation function. Compared with the prior HVDC-DC converting device, the HVDC-DC power electronic converter transformer has the advantages of small volume and light weight.

The invention discloses an online detection method and protection device for direct current system arc faults. Characteristics of current alternating components of a power circuit in the power-on starting process, the normal work process and the overload fault process of the power circuit and characteristics of the current alternating components of the power circuit during arc generating are combined, selected arc current characteristic components include peak-to-peak values and standard deviations of a time domain and a frequency component power sum within the range from 1 kHz to 100 kHz after noise of specific frequency points of a load is filtered, mahalanobis distance values of the real-time characteristic components and the characteristic components in the power-on starting process, the normal work process and the overload fault process of the power circuit through a mahalanobis distance algorithm, and the mahalanobis distance values are compared with a threshold value set in the learning process to detect whether a single arc is generated or not. By means of the technical scheme, the online detection method and protection device have advantages of being high in university, high in detection rate and low in misjudgment rate, and can be widely applied to low-voltage and high-voltage electric power systems and photovoltaic cell systems of airplanes, electric vehicles and ships, and civil high-voltage direct current power distribution systems.