214 results about "Ac power system" patented technology

A solar cell assembly including a plurality of solar cells is formed on a common substrate, and a DC / DC converter which converts the output from the solar cell is connected to each solar cell to constitute a solar power generation apparatus. The output from the solar power generation apparatus is converted into an AC power by an inverter and supplied to a load or commercial AC power system. Since the arrangement is simplified, the manufacturing cost can be reduced, and the influence of partial shade or a variation in characteristic decreases.

A solar cell assembly including a plurality of solar cells is formed on a common substrate, and a DC / DC converter which converts the output from the solar cell is connected to each solar cell to constitute a solar power generation apparatus. The output from the solar power generation apparatus is converted into an AC power by an inverter and supplied to a load or commercial AC power system. Since the arrangement is simplified, the manufacturing cost can be reduced, and the influence of partial shade or a variation in characteristic decreases.

A gas turbine generating apparatus according to the present invention comprises a gas turbine capable of a high-speed operation, a permanent-magnet-type generator driven at a high speed by the gas turbine, an inverter device (5) for converting alternating-current power generated by the generator into commercial alternating-current power, and a system-interconnection device (9) for interconnecting output of the inverter device to a commercial AC power supply system (10). The system-interconnection device controls the inverter device based on voltage of the commercial AC power supply system as a criterion such that output current of the inverter device is in phase with the voltage or out of phase with the voltage by a constant phase difference. A control device (18) is provided for operating the permanent-magnet-type generator (4) as a motor at a time of starting the gas turbine, and supplying alternating-current power from a direct-current power supply through the inverter device or another inverter device in addition to the inverter device to the generator for increasing a rotational speed smoothly from zero. The control device detects output current of the inverter device and controls the inverter device to keep the output current constant.

An active filter (300) generates multi-phase compensating current in an AC power supply system (10) that supplies a load (200). The filter (300) includes a compensating current output device (34) outputting multi-phase compensating current to an AC power line (50); and a controller (310) for controlling the compensating current output (340) such that the multi-phase compensating current compensates for current harmonics and power factor on said AC power line (50). The controller (310) estimates current harmonics and power factor compensating values as a function of multi-phase power measurements.

A bidirectional switching device has a first main semiconductor element and a second main semiconductor element. The first main semiconductor element has a first main electrode connected to an ungrounded side of an AC power source, and a second main electrode. The first main semiconductor element contains a first parasitic diode whose cathode region is connected to the first main electrode and whose anode region is connected to the second main electrode. The second main semiconductor element has a third main electrode connected to the second main electrode, and a fourth main electrode connected to a load. The second main semiconductor element contains a second parasitic diode whose anode region is connected to the third main electrode and whose cathode region is connected to the fourth main electrode. A current flowing from the first main semiconductor element toward the second main semiconductor element passes through the second parasitic diode, and a current flowing from the second main semiconductor element toward the first main semiconductor element passes through the first parasitic diode. The bidirectional switching device is used to form a semiconductor active fuse for an AC power system. The semiconductor active fuse is capable of detecting an overcurrent without a shunt resistor, which was connected in series to a power supply cable, thereby minimizing heat dissipation as well as a conduction loss. The semiconductor active fuse is capable of easily and speedily detecting not only an overcurrent caused by a dead short but also an abnormal current caused by an incomplete short circuit failure having a certain extent of short-circuit resistance, and breaking alternating current in an AC power supply cable.

A system and method for responding to abrupt load changes on a power system transfers an initial amount of power from an external power source to the AC power system through a secondary converter module; senses an abrupt load change occurring-on the AC power system; and transfers auxiliary direct current (DC) power to the secondary converter module.

A system and method for controlling power flow between power sources and a load in a power system are disclosed. Briefly described, one embodiment is a method for transferring power from a plurality of power sources to an AC system through an IPC module. The IPC module receives a first amount of power from a first power source that is external to the IPC module, receives a second amount of power from a second power source that is external to the IPC module, controls at least a first amount of direct current (DC) power through a first primary converter module coupled to a DC bus, receives a second amount of DC power from a second primary converter module coupled to the DC bus, converts the first and the second amounts of DC power into AC power, and transfers the AC power to the AC power system.

A system and method for transferring power from power sources to an AC power system are disclosed. Briefly described, one embodiment electrically couples an external AC power source to a first input power control (IPC) module that is rated at a first AC input power capacity and that is rated at a first direct current (DC ) input power capacity, operates the first IPC module up to the first AC input power capacity in response to receiving AC power from an external AC power source, electrically couples an external DC power source to a second IPC module that is rated at a second AC input power capacity and that is rated at a second DC input power capacity, and operates the second IPC module up to the second DC input power capacity in response to receiving DC power from an external DC power source.

A power protection device protects electronic equipment from AC supply system disturbances. An electronically controlled relay circuit passes power to connected equipment if the electrical supply system, to which the equipment is connected, is properly wired for continuity and correct polarity of line, neutral, and ground conductors, and the line voltage is within twenty-five percent of nominal levels. Thermal cut-offs are used as a back-up to the over-voltage protection provided by the electronically controlled relay circuit. These thermal cut-offs are connected in a way that when either or both trip, the relay of the electronically controlled relay circuit is de-energized and power is disconnected to the device output stage and connected equipment.

The invention discloses a switching power supply with a function of correcting a power factor and a control device thereof. The control device of the switching power supply comprises a power factor corrector and a total harmonic distortion optimizer. An output end of the power factor corrector is connected with a power tube and the power factor corrector is used for determining turnon time and turnoff time of the power tube. An AC (alternate current) input voltage is input through an input end of the total harmonic distortion optimizer. An output end of the total harmonic distortion optimizer is connected with the power factor corrector. An AC input signal can be dynamically tracked by the total harmonic distortion optimizer. When the AC input voltage is increased, a peak current of an inductance of the switching power supply is reduced and a current that an AC power system charges a filter capacitor of the switching power supply is compensated; and when the AC input voltage is reduced, the peak current of the inductance of the switching power supply is increased and a current that the AC power system discharges the filter capacitor of the switching power supply is compensated. By utilizing the control device disclosed by the invention, the total harmonic distortion of the AC input current caused by the filter capacitor can be reduced and the power factor of the switching power supply is improved.

A method and an apparatus are disclosed for disconnection of a fault current which has occurred in an AC power supply system. A disconnection command which is produced in a protective device is supplied to a synchronization controller in order to open a circuit breaker, in which synchronization controller a command is delayed until the circuit breaker can be opened in synchronism with the power supply system. The method includes monitoring of the disconnection command emitted from the protective device and monitoring a fault-current signal, or a status signal emitted from the circuit breaker, and formation of an emergency disconnection command if the fault-current signal or the status signal is still present following a delay time after emission of the disconnection command, which delay time is greater than a sum of a natural response time of the circuit breaker and a time for quenching of a switching arc produced on opening of the circuit breaker.

The over-voltage monitor sensor for 110KV-50KV ac power system comprises: a shell, a disk, a voltage-division capacitor / resistance, a matching resistance, a protective unit, and the co-axial cable. This invention can bear large impact voltage, can respond the signal fast, and has wide application for high precision and stability.

A system and method for responding to abrupt load changes on a power system are disclosed. Briefly described, one embodiment transfers an initial amount of power from an external power source to the AC power system through a secondary converter module; senses an abrupt load change occurring on the AC power system; where, in response to sensing the abrupt load change, transfers auxiliary direct current (DC) power to the secondary converter module, wherein the auxiliary DC power corresponds to at least a portion of the abrupt load change; where, in response to sensing the abrupt load change, transfers the initial amount of power from the external power source and the auxiliary DC power through the secondary converter module to the AC power system; and where, in response to sensing the abrupt load change, maintains transfer of the initial amount of power from the external power source through the secondary converter module.

In one aspect of the invention, an isolated power converter suitable for high power and high voltage applications comprises stacked rectifiers and lossless snubber circuits with inductors that prevent snubber diodes from delivering large current pulses into output filter capacitors when the duty cycle of the inverter is low, thereby allowing effective snubbing without unduly restricting the voltage conversion range of the power supply. In another aspect of the invention, control circuitry of a power supply comprises both a high bandwidth input current regulator and a low bandwidth output voltage regulator. The combination of a wide bandwidth input current regulator and a low bandwidth output voltage regulator allows the power supply to emulate an inductively loaded uncontrolled rectifier while restricting negative input impedance characteristics to frequencies that are substantially lower than the frequency of the ac power system.

Apparatus and methods are disclosed for providing VAR compensation using an AC motor drive, in which an off-line motor drive is configured to prevent power transfer to a motor load output, with a line side converter being operated to control a voltage or current in an intermediate circuit for leading or lagging VAR compensation of an AC power system.

Alternating current power systems for powering cordless power tools are disclosed. An electrical power assembly comprises an alternating current to direct current (“AC / DC”) converter connected to a power interface adapter. The AC / DC converter receives alternating current through an electrical socket and generates direct current. A power interface adapter shaped similarly to the replacement battery packs is connected to the cordless power tools and feeds the direct current to the cordless tool. The AC / DC converter may be located within the power interface adapter or a wall-mountable electrical connector.

Upon power failure of a commercial power source, an automatic switching device switches to power supply from a hybrid vehicle. An ECU of the vehicle, when receiving a request for generation of a commercial AC voltage, sets an upper-limit power generation amount based on a remaining amount of fuel. The ECU transmits the upper-limit power generation amount via an antenna to an on-premises ECU, while controlling a power generation amount based on the upper-limit power generation amount. The on-premises, when receiving the upper-limit power generation amount, controls the load state such that commercial AC power is supplied firstly to a first load of priority level 1, according to proprieties registered in advance, and such that the amount of the power supplied to the electric loads does not exceed the upper-limit power generation amount.

The invention relates to an overvoltage sensor of overhead transmission lines, relating to an overvoltage monitoring device of the overhead transmission line of an AC power system. The sensor consists of a voltage monitoring unit and a data acquisition unit, and is characterized in that the voltage monitoring unit mainly comprises an overhead transmission line, a sensing metal plate, a screening shell, a stainless steel screening box, a voltage-dividing capacitor, a front end protection circuit, a matched resistance, a coaxial-cable and the like. The sensor has the effects of simple structure, small volume, light weight, convenient installation, low cost, high safety, good universality, high linearity and high accuracy on testing overvoltage and the like. The invention can be widely used as the voltage sensor of the overhead transmission line, especially be applicable to overvoltage sensor of 10kV to 1000kV overhead transmission lines.

An islanding detection method is proposed to overcome the incapability of detecting islanding operations in accordance with prior arts. A distortion for causing a variation of an AC power system is performed, and an AC power system frequency and a voltage variation are detected as the bases for determining the occurrence of an islanding operation.

A system and method for controlling power flow between power sources and a load in a power system are disclosed. Briefly described, one embodiment is a method for transferring power from a plurality of power sources to an AC system through an IPC module. The IPC module receives a first amount of power from a first power source that is external to the IPC module, receives a second amount of power from a second power source that is external to the IPC module, controls at least a first amount of direct current (DC) power through a first primary converter module coupled to a DC bus, receives a second amount of DC power from a second primary converter module coupled to the DC bus, converts the first and the second amounts of DC power into AC power, and transfers the AC power to the AC power system.

Power generated by a solar battery of thin-film type is stepped up to a predetermined DC voltage by a step-up chopper circuit, and the predetermined DC voltage is converted into three-phase AC power by an inverter circuit, and the three-phase AC power is supplied to an AC power supply system via an output DC voltage circuit. The solar battery is not grounded, and a negative electrode thereof has a floating capacitance between the negative electrode and the ground. The AC power supply system is configured by three-phase star-connection, and the neutral point is grounded. The output DC voltage circuit includes three batteries, and the batteries are provided, for the respective phases, between the AC power supply system and a sine wave filter connected to the AC output side of the inverter circuit. Therefore, it is possible to prevent acceleration of the deterioration of the solar battery.

The invention provides a power regulation circuit, a regulator and a voltage regulation method for three-phase AC circuits, wherein an AC power regulator is connected with load sides of circuits of each phase in a three-phase AC power system; on the basis of connecting a voltage stabilizer in series with a power frequency transformer to compensate input voltage, a variable capacitance unit is also connected in series; and by adjusting the transformation ratio d' of the transformer of each phase and the transformation ratio d of an AC chopper, the output voltage of three-phase circuits is enabled to have the same amplitude, and the phase-angle difference between the three-phase circuits is 120 degrees. Therefore, the regulator balances three-phase voltage and then performs reactive power compensation on loads, thereby eliminating the influence of inductive loads on the circuits, considerably reducing reactive power loss and improving power factor.

The invention discloses a control structure and method for a virtual synchronous machine of a voltage source converter based high voltage direct current (VSC-HVDC) system. The control structure comprises a VSC virtual synchronous machine, wherein the VSC virtual synchronous machine is connected with a power grid through a grid-connected gateway KS. The control system of the control structure comprises an active power regulation module, a reactive power regulation module, a mechanical module and an electrical module. By inertia and impedance characteristics of a VSC simulation synchronous power generator and functions of frequency regulation and voltage regulation, the stability of an AC power system is improved, and seamless switching of grid-connected and island modes is achieved. The method comprises a DC voltage control method and an active power control method, can be used for all VSC applications in the VSC-HVDC system and has the function of coordinated control on a DC voltage, and the running reliability of a DC system is improved.

The invention discloses a voltage sensor of an ac power system, which relates to a voltage signal catching device of the ac power system. The voltage sensor of the invention is composed of substation capacitive equipment, a current coil, an electronic transforming unit, an earth lead, and a coaxial cable. The voltage sensor of the invention can work under power frequency exchanging circumstance for a long time and can bear big attacking electric voltage, outputting signals of the voltage sensor are separated thoroughly with an electrified wire netting though only once separation. The invention has the advantages of small volume, light weight, convenient installment. The preciseness of testing power frequency voltage signals can be reached to 1 grade, uncertainty of voltages peak values which are tested and operated is less then +-1%, the uncertainty of time parameters is in a range of +-3%, and thereby the invention can apply for collecting the electric signal of an electric system 10kV to 500kV.

Improved devices, apparatuses, systems, and methods involving the use of field probes with voltage-controlled variable impedance elements and surface-launched acoustic wave devices, including surface acoustic wave (SAW) devices and SAW sensor-tag wireless interface devices to measure voltage and current in current carrying conductors (CCCs) via measurement of the electric fields and magnetic fields around said CCCs are disclosed. The devices, apparatuses, systems, and methods taught in the present invention include a remotely powered line-mounted measurement unit that requires no connection to electrical ground for operation, and that has no internal energy source, no energy harvesting or power conditioning circuitry, no discrete energy storage components, and no radio. The devices, apparatuses, systems, and methods taught in the present invention also provide for determining the phase (leading or lagging) of the current relative to the voltage in AC power systems, and also provide for measurement of temperature of the conductor.

According to one embodiment, an AC power system includes a first AC / DC converter to be coupled to a direct current (DC) load and a multi-phase AC power supply. The system further includes a second AC / DC converter coupled in parallel with the first AC / DC converter via an interphase transformer to the DC load and the multi-phase AC power supply. The system further includes a controller coupled to the first and second AC / DC converters, where the controller is configured to generate a gate trigger signal for firing each of the rectifiers for the first and second AC / DC converters. During a first power cycle, a rectifier of the first AC / DC converter is fired at a firing angle advanced to a firing angle of a corresponding rectifier of the second DC / DC converter. During a second power cycle, the rectifier of the first AC / DC converter is fired at a firing angle lagging to a firing angle of the corresponding rectifier of the second AC / DC converter.