281 results about "Reactive load" patented technology

A method for determining an optimal compression of tissue to apply a surgical element has the steps of applying a load to the tissue. The method has the step of determining a reactive load applied by the tissue in response to the load. The method also has the step of determining the reactive load per unit time for a predetermined time period and determining a slope of the reactive load per unit time. The method further has the steps of evaluating the slope relative to a predetermined threshold, and signaling when the slope exceeds the predetermined threshold.

The present invention generally relates to power electronic switching circuits and in particular to inverter modules employing two or more controlled switches that can be used with reactive loads. An inverter circuit is provided which comprises first and second input terminals for being connected to a DC power source; first and second output terminals for outputting an AC voltage; at least one metal oxide semiconductor field effect transistor, MOSFET, having a parasitic body diode. The inverter circuit further comprises at least one disabling element for disabling said body diode. This may result in an improved efficiency of the inverter circuit in combination with a reactive power capability. Further, a semiconductor switching device is disclosed, comprising at least one metal oxide semiconductor field effect transistor, MOSFET, and at least one insulated gate bipolar transistor, IGBT, wherein said MOSFET and said IGBT are connected in parallel.

An integral method for realizing parallel generation and network reactive power compensation at the same time is based on the transient reactive power theory applying park transfer to transform a three phase inverter output current to a rotation dq coordinate to realize separation of active current and reactive current to convert the DC current of the photovoltaic to AC current by controlling the currents and directions carry out reactive power compensation to the local network. When a photovoltaic battery has enough energy to output, it realizes parallel generation and reactive compensation at the same time, when it stops the output, the inverter compensates the network independently.

A voltage control arrangement for a system of multiple windfarms with transmission lines. Voltage is regulated at a point of regulation on the system, such as a high voltage substation or other system bus. Regulation is achieved at the point of regulation by sensing the voltage, comparing to a reference voltage, and adjusting the reactive power output of the wind turbines and other equipment in the system. The regulation point may be shifted to another point if needed to respect voltage limits at that points of the system after attempting to shift reactive load to restore voltage within limits at the other points in the system. The reference voltage may be adjusted to minimize losses for the system of multiple windfarms and transmission lines. A loss optimizing algorithm is applied to the combined multiple windfarm and transmission line to shift reactive load among local windfarms to minimize losses and to shift reactive load among individual wind turbines within an individual windfarm.

A method for calculating power flow solution of a power transmission network with unified power flow controllers is adapted to calculate the power flow on a large-scale power transmission network. The unified power flow controller has a series transformer, a series converter, a direct current coupling capacitor, a shunt converter, and a series transformer. The shunt transformer is connected electrically to a sending-end bus. The series transformer is connected electrically to the sending-end bus and a receiving-end bus. The unified power flow controller is represented by equivalent active and reactive loads on the sending-end and receiving-end buses of the power transmission network.

The invention provides a direct-current (DC) microgrid system and an energy management method thereof. A power generation unit comprises a large user-side power grid and a grid-connected alternating current / direct current converter (AC / DC) thereof, a lithium iron phosphate energy storage system (EMS) and an energy storage direct current / direct current converter (DC / DC), and a photovoltaic power generation system and a photovoltaic DC / DC thereof. The DC microgrid system is provided with EMS and a wireless sensor network thereof, wherein the wireless sensor network is communicated with the grid-connected, energy storage and photovoltaic DC / DC; the EMS is used for executing different control strategies and optimizing the operation of a DC microgrid; the voltage of a DC busbar is stabilized by controlling a DC busbar voltage outer loop and an output inductive current inner loop through the grid-connected AC / DC when a grid-connected operation is switched to an islanding operation; and the islanding operation is switched to an operation using the energy storage DC / DC as a voltage source, i.e. the voltage stability of the DC busbar is maintained by controlling the DC busbar voltage outer loop and the inductive current inner loop on the energy storage side of a battery within the time of at most 20ms. Therefore, a seamless switching requirement is met, uninterrupted power supply (UPS) of loads in a telecom data center is realized, and configuration of reactive-load compensation equipment is avoided.

A method to design antennas with broadband characteristics. In an exemplary embodiment, a method comprises loading an antenna structure with multiple reactive loads. The multiple loads are synthesized by applying the theory of Characteristic Modes. Another exemplary embodiment includes an antenna adapted to have broadband characteristics. One example is a wire dipole antenna. In an exemplary embodiment, a loaded antenna may be adapted to resonate an arbitrary current over a wide frequency band. The loads may require non-Foster elements when realized. Exemplary embodiments may include the broadband characteristics of the both the input impedance at the terminal of the antenna as well as the radiation pattern.

A method for calculating power flow solution of a power transmission network with unified power flow controllers is adapted to calculate the power flow on a large-scale power transmission network. The unified power flow controller has a series transformer, a series converter, a direct current coupling capacitor, a shunt converter, and a series transformer. The shunt transformer is connected electrically to a sending-end bus. The series transformer is connected electrically to the sending-end bus and a receiving-end bus. The unified power flow controller is represented by equivalent active and reactive loads on the sending-end and receiving-end buses of the power transmission network.

The sectional detection method of small current earthing fault of power system, especially single phase long distance system, is suitable for system with several detection units in different sectionsof the line. Each unit variance in zero-sequence voltage or current is used as fault starting condition, the transient zero-sequence current amplitude and initial polarity are calculated, and the main station determines the fault section based on the fault information the detectors report. The basic criterion is that the transient zero-sequence currents on two sides of the fault point have opposite polarity and that each transient zero-sequence current amplitude is proportional inversely to the distance to the fault point. The said method is suitable for system with unearthed neutral point, earthed arc extinguishing coil or high earthing resistance as well as system with reactive load.

A tensioner system for a top-tensioned riser in a floating platform includes a hydro-pneumatic tensioner assembly resiliently mounted to the floating platform, and a riser support conductor surrounding the riser coaxially, wherein the support conductor conveys a pull-type tensional force from the hydro-pneumatic tensioner assembly to the riser through a riser conductor coupling assembly that engages the tensioner assembly and the riser support conductor to convey the tensional force. A riser tension joint support assembly conveys the tensional force from the riser support conductor to a riser tension joint on the riser. The tensioner assembly compensates for relative platform motion including pitch, heave, and yaw. Also a reactive load assembly is mounted to the platform and reacts to a two-point dynamic bending moment imposed on the riser support conductor, while resisting riser support conductor rotation.

A point-to-point communications system (20) for transmitting messages from any location (A) within a power distribution system or network (10) to any other location (B) within the network. A transceiver (12) at the one location includes a transmitter (X) that impresses a waveform (WR) on a waveform (WG) propagated by the network to supply power throughout the network. The transmitter is a resonant transmitter that includes a reactive load (13) which is selectively connected to and disconnected from the power distribution network. A controller (16) controls operation of the transmitter to connect and disconnect the reactive load from the network so to impress on the propagated waveform a dampened sinusoidal waveform whose characteristics represent information conveyed over the power distribution system. A receiver (Yn) at the other location receives and demodulates the dampened sinusoidal waveform to extract therefrom the information being conveyed by it.

A light emitting diode (LED) and associated driver circuit wherein the LED is mounted on the front of a switchplate and the driver circuit on the back of the switchplate. The LED is mounted at a downward angle on the outside of the switchplate so as to light a pathway beneath the switchplate. The drive electronics are designed to work with a return path through an electrical load. Additionally, the LED driver circuit is designed to allow operation of the LED with both resistive and reactive loads controlled by the switch to which the switchplate is connected. The device is also designed to be connected to any electrically valid combination of 2-way, 3-way, and 4-way switches either singly or in combination.

The present invention is a high voltage synch motor digitalized vector control device which comprises a high voltage input dephasing isolating transformer and a power unit module that is provided with energy feedback. The two units are connected in series to form a three-phase high voltage variable frequency output. The present invention also consists of a digital processor, a programmable logic component, a digital high voltage synchronous machine vector controller that is formed by relative surrounding circuit, a rotor position and speed feedback encoder that is connected with the controlled synchronous motor with the same axle and a monitor transducer of the output current of the frequency changer; the surrounding circuit consists of an optical fiber connector and an upper monitor system that gives frequency. The present invention has the advantages of less pollution to the grid, needless of reactive-load compensation equipment, fast response, wide range of speed regulation ratio, actuated by constant torque and quadrant operating power.

A quarter wave coaxial cavity resonator for producing corona discharge plasma from is presented. The quarter wave coaxial cavity resonator has a folded cavity made of opposing concentric cavity members that are nested together to form a continuous cavity ending in a aperture. A center conductor with a tip is positioned in the cavity. The folded cavity advantageously permits the coaxial cavity resonator to resonate at a lower operating frequency than an unfolded quarter wave coaxial cavity resonator of the same length. Embodiments of the quarter wave coaxial cavity resonator use narrower apertures to reduce radiative losses, and include center conductors that are reactive load elements, such as helical coils. When a radio frequency (RF) oscillation is produced in the quarter wave coaxial cavity resonator, corona discharge plasma is formed at the tip of the center conductor. The corona discharge plasma can be used to ignite combustible materials in combustion chambers of combustion engines.

The present invention provides a substation voltage control method of realizing comprehensive coordination of continuous equipment and discrete equipment, belonging to power system automatic voltage control technical field. The method includes following steps: collecting the real-time operation data of the substation to be controlled when the control cycle starts; judging each collecting variable based on the preestablished expert rules, calculating the tap joint gear position control variable of the regulating transformer or determining adjustment reactive-load compensation equipment; if is a adjustment reactive-load compensation equipment, the needed reactive-load adjusting variable delta Qg is calculated, the delta Qg processes reactive distribution calculation between a synchronous condenser and a capacitor reactance, the reactive set value of the synchronous condenser and the capacitor reactance sequence needed switch are calculated; the state of the transformer equipment is adjusted according to the obtained reactive set value and the capacitor reactance sequence needed switch and the tap joint gear position control variable of the transformer, realizing ring closed control. The invention improves ability of network bearing accident disturbance, improving the security of the network.

The invention relates to a smart grid realization method of an on-line voltage-stability safety estimation system, which comprises the following steps: 1, calculation grids are constructed in a network environment according to a calculation requirement; 2, a coordinating manager engine acquires real-time state estimation section data from an SCADA / EMS system; 3, a calculation manager engine performs power flow convergence check on the real-time state estimation section data to form a calculation task pool; 4, calculation node engines apply for calculation; 5, the calculation manager engine generates mixed voltage stability index information with the influences of active load and reactive load taken into consideration comprehensively according to calculation results sent by each calculation node and identifies weak nodes of a power grid by sorting; and 6, the information of the identified weak nodes of the power grid are written into a database and are refreshed periodically to display a voltage-stability safety estimation result in graph. The method can exert the calculation capability of each calculation node to the maximum, can effectively implement the dynamic load balance, and has high dynamic scalability and fault tolerance.

A tensioner system for a top-tensioned riser in a floating platform includes a hydro-pneumatic tensioner assembly resiliently mounted to the floating platform, and a riser support conductor surrounding the riser coaxially, wherein the support conductor conveys a pull-type tensional force from the hydro-pneumatic tensioner assembly to the riser through a riser conductor coupling assembly that engages the tensioner assembly and the riser support conductor to convey the tensional force. A riser tension joint support assembly conveys the tensional force from the riser support conductor to a riser tension joint on the riser. The tensioner assembly compensates for relative platform motion including pitch, heave, and yaw. Also a reactive load assembly is mounted to the platform and reacts to a two-point dynamic bending moment imposed on the riser support conductor, while resisting riser support conductor rotation.

The invention provides a self-adapted load type distribution transformer. The self-adapted load type distribution transformer comprises a distribution transformer body unit, an on-load capacity-adjusting and voltage-adjusting integrated unit, an associated equipment unit and a comprehensive control unit, wherein the distribution transformer body unit and the on-load capacity-adjusting and voltage-adjusting integrated unit are connected in a unidirectional manner; and the on-load capacity-adjusting and voltage-adjusting integrated unit and the associated equipment unit are connected with the comprehensive control unit in a bidirectional manner respectively. According to the self-adapted load type distribution transformer disclosed by the invention, real-time operation data of the transformer, gear information of on-load capacity-adjusting switch equipment and on-load voltage-adjusting switch equipment, and equipment state information of online load phase-adjusting equipment and split-phase reactive-load compensation equipment are collected in real time, and comprehensive analysis and judgment can be carried out through a comprehensive analysis and judgment decision-making module to form a corresponding control policy and implement corresponding control operation. Economic operation manner selection, voltage adjustment, three-phase load unbalance management and reactive local balance under an on-load state of the distribution transformer can be realized, and the intelligent level of the distribution transformer and the self-adapted capability to a load are greatly improved.

The invention provides a DC high-current ice-melting device with static reactive-load compensation function, pertaining to the technical field of supporting equipments of high / low voltage power supply / distribution systems. The primary side of a three-winding rectification transformer is merged on a three-phase bus, two secondary sides are respectively connected with the intermediate points of a positive-end three-phase high-voltage high-current controllable silicon valve and a negative-end high-voltage high-current controllable silicon valve; the anodes and cathodes of the two three-phase high-voltage and high-current controllable silicon valves form a 12-pulse rectifier; the anode of the positive-end three-phase high-voltage high-current controllable silicon valve is connected to a DC reactor in series to achieve a positive terminal, and the cathode of the negative-end high-voltage high-current controllable silicon valve forms a negative terminal, a shorting stub is arranged between the positive terminal and the negative terminal. The invention integrates DC high-current ice-melting technology and static reactive-load compensation function, thereby, the device can not only be used as a static reactive-load compensation device, but also be used as a current-controllable DC high-current ice-melting device; as a result, the cost of supporting equipment for low / high voltage supply / distribution system is reduced remarkably, and the utilization ratio of the equipment is largely improved.

A voltage or power conditioning and control device may be used in line with a source of AC line power and a reactive load such as a single-phase induction motor. The device operates to absorb some of the power reflected by the AC load and generate a synthetic power wave to supplement and correct the applied power in level and phase. The device employs a pair of power capacitors, and a pair of electronic switch devices each with a diode in parallel. Gating or command signals are generated based on the line voltage and timing, e.g., zero crossings. The phase or timing of the command signals is selected for a normal or no-boost mode, a voltage boost mode, or a voltage reduction mode. The capacitors are considered in series with the load, and improve the power factor to the load. A variation of this device may be used in conjunction with a solar array or other local power source.

The invention provides an intelligent marshalling combination switch, comprising an AC electronic switch, a magnetic latching relay and a control circuit. The intelligent marshalling combination switch is characterized in that the control circuit is connected with at least a group of combination switches; the structure of the combination switch is that the AC electronic switch is connected in parallel with the magnetic latching relay with one-way contacts; the parallel end is connected in series with the magnetic latching relay with bidirectional contacts and the other parallel end is connected with one end of a single-phase capacitor and one end of a discharge coil; the other end of the single-phase capacitor and the other magnetic latching relay with bidirectional contacts are connected in series with each other and are connected into a return circuit. The intelligent marshalling combination switch can lead the single-phase capacitor to be freely switched without disturbance between the phase lines of the three-phase AC circuit and between the phase line and the zero line of the three-phase circuit, realizes the star-delta unequal arbitray connection of the single-phase capacitor under the control of a controller, completes adjusting the asymmetrical active load of the transformer and compensating the reactive loads at the same time, leads the transformer to be changed from the asymmetrical running to the symmetrical running, saves the power energy, and leads the power supply to have high quality and reliable running.

The present invention is illustrated in a method of power factor control for a power regulation system connected for supplying electric power to a reactive load. The system includes a microcomputer for supplying gating signals to an electronic switching device such as a triac for controlling the conduction phase angle of the triac to control the application of alternating current (AC) electric power to the load. The method comprises monitoring of the waveform of the AC voltage applied to the load and determining for each of the half-cycles of the waveform a timed event when the absolute value of the magnitude of the waveform transitions through a reference magnitude. A peak of the voltage waveform is determined. The process is repeated for the AC current waveform and the corresponding peaks of the current waveform identified. The time delay between a designated peak of the voltage waveform and a designated peak of a corresponding half-cycle of the current waveform is representative of the power factor of power supplied to the load and the applied voltage is adjusted in a manner to bring the power factor towards unity, i.e., by reducing the measured time delay. The system also monitors peak values of the AC current and limits the power factor adjustment to prevent current values from falling below a selected minimum value so as to prevent motor stall or overheat. Typically, the adjusting process removes voltage from the load for a portion of each half-cycle of the AC voltage waveform either by gating the triac out of conduction at beginning or end of a half-cycle or by pulse width modulation.

The invention discloses a control method for large wind field reactive-load compensation equipment in low voltage ride through. The control method comprises the follow steps that firstly, information of voltage, current, power and frequency in a power grid is sampled through coordination control of an automatic voltage control system, fault points are detected, and when draught fan low voltage ride through starts, a static var generator is rapidly started to provide reactive power; secondly, compensation capacity of various types of reactive-load compensation equipment is determined according to different installation places and effects of the reactive-load compensation equipment and different principles; thirdly, the static var generator respectively achieves the reactive compensation work state and the harmonic suppression work state by using different control strategies; fourthly, the automatic voltage control system starts a thyristor switched capacitor when power voltage is equal to pre-charged voltage of the thyristor switched capacitor; fifthly, the automatic voltage control system starts a thyristor controlled reactor according to reactive gap information; the fourth step and the fifth step are in parallel with each other.

The invention provides a power distribution network dynamic power restoration method based on a load curve, which belongs to the technical field of power distribution system automation. The method utilizes a computer, realizes computing through programs and comprises the steps of inputting basic parameters; computing active load and reactive load of each node in each hour and determining a grid structure in normal operation; determining a fault section, a power supply path of the power side of the fault section and a grid structure after failure isolation; applying a traditional genetic algorithm to determine a candidate grid structure set of the least loss load in each hour during fault restoration; finally determining the optimum dynamic power restoration scheme during fault restoration. The method fully utilizes the load curve, and the dynamic restoration scheme is formulated by hour, so that the grid structure changes along with the change of the load during fault restoration, and accordingly, the method has the characteristics of being capable of effectively reducing power failure areas caused by fault, shortening power failure time for users, reducing the power failure loss of the users, and the like. The method can be widely applied to power distribution network power restoration.

The invention discloses a performance testing system of a large-capacity reactive power dynamic compensating device, comprising a detected reactive power dynamic compensating device, wherein the performance of the dynamic compensating device is to be detected. The performance testing system is characterized by also comprising an electric energy quality analyzer, a high-voltage switch cabinet, an active load and an inactive load, wherein the active load is externally connected with a power grid by the high-voltage switch cabinet and is connected with the dynamic reactive power compensating device in parallel; and the inactive load provides adjustably capacitive or inductive reactive power having the property opposite to the property of the reactive power generated by the detected reactive power dynamic compensating device. The performance testing system has the beneficial effect that a full load test and a system performance test are carried out for the large-capacity reactive power dynamic compensating device by smaller-capacity power grids in factories or laboratories. The quality problem possibly existing in the device is easier to find to ensure that the device is successively put into operation once on the scene.

The present disclosure is directed to a system and method for balancing reactive power loading between multiple renewable energy power systems coupled to a power grid at a point of regulation (POR). The method includes determining a voltage error based on a voltage reference and a measured voltage at the POR. The method also includes measuring at least one operating condition from each of the power systems. Further, the method includes determining a per unit actual reactive power for each of the power systems based on at least one of the actual operating conditions and determining a per unit average reactive power from the power systems based on at least one of the actual operating conditions. Thus, the method also includes determining a voltage reference command for each of the power systems as a function of the voltage error, the per unit reactive power, and / or the per unit average reactive power.