3008 results about "Voltage fluctuation" patented technology

The present invention relates to a method for operating a wind turbine with an electrical generator, drivable by a rotor, for supplying electrical power to an electric grid, in particular to the loads connected thereto. The object of the present invention is to define a method for operating a wind turbine and to provide a wind turbine and/or a wind farm that is capable, even when the output of non-reactive power fluctuates, of reducing or at least of insignificantly increasing the unwanted fluctuation in voltage at a predefined point in the grid compared to the situation with no wind turbine(s). Method for operating a wind turbine with an electrical generator, drivable by a rotor, for supplying electrical power to an electric grid, in particular to the loads connected thereto, characterized in that the phase angle φ is changed in response to at least one voltage measured in the grid.

A method for operating a wind turbine and to provide a wind turbine and/or a wind farm that is capable, even when the output of non-reactive power fluctuates, of reducing or at least of insignificantly increasing the unwanted fluctuation in voltage at a predefined point in the grid compared to the situation with no wind turbines. Method for operating a wind turbine with an electrical generator, drivable by a rotor, for supplying electrical power to an electric grid, in particular to the loads connected thereto, characterized in that the phase angle φ is changed in response to at least one voltage measured in the grid.

A multichannel cochlear implant system spatially spreads the excitation pattern in the target neural tissue by either: (1) rapid sequential stimulation of a small group of electrodes, or (2) simultaneously stimulating a small group of electrodes. Such multi-electrode stimulation stimulates a greater number of neurons in a synchronous manner, thereby increasing the amplitude of the extra-cellular voltage fluctuation and facilitating its recording. The electrical stimuli are applied simultaneously (or sequentially at a rapid rate) on selected small groups of electrodes while monitoring the evoked compound action potential (ECAP) on a nearby electrode. The presence of an observable ECAP not only validates operation of the implant device at a time when the patient may be unconscious or otherwise unable to provide subjective feedback, but also provides a way for the magnitude of the observed ECAP to be recorded as a function of the amplitude of the applied stimulus. From this data, a safe, efficacious and comfortable threshold level can be obtained which may be used thereafter as the initial setting of the stimulation parameters of the neurostimulation device, or to guide the setting of the stimulation parameters of the neurostimulation device.

Disclosed herein are a variety of different electrical system topologies intended to mitigate the impact of large intermittent loads on a 12 volt vehicle power distribution system. In some embodiments the intermittent load is disconnected from the remainder of the system and the voltage supplied to this load is allowed to fluctuate. In other embodiments, the voltage to critical loads is regulated independently of the voltage supplied to the remainder of the system. The different topologies described can be grouped into three categories, each corresponding to a different solution technique. One approach is to regulate the voltage to the critical loads. A second approach is to isolate the intermittent load that causes the drop in system voltage. The third approach is to use a different type of alternator that has a faster response than the conventional Lundell wound field machine.

The invention provides a compensation method of direct current (DC) voltage fluctuation of a photovoltaic grid-connected inverter, and the method can be used for improving the quality of the grid-connected current through compensating an input DC side secondary pulse voltage by adding a DC voltage pulse compensation module in a DC/AC (direction current/alternating current) high-frequency link, and eliminating a grid-connected current harmonic wave caused by the DC voltage pulse. The control performance of the system can be improved without adding a filter device and adding any extra appliance.

The present invention provides a primary-side flyback power converter that supplies a constant voltage output and a constant current output. To generate a well-regulated output voltage under varying load conditions, a PWM controller is included in the power converter in order to generate a PWM signal controlling a switching transistor in response to a flyback voltage sampled from a first primary winding of the power supply transformer. Several improvements are included in this present invention to overcome the disadvantages of prior-art flyback power converters. Firstly, the flyback energy of the first primary winding is used as a DC power source for the PWM controller in order to reduce power consumption. A double sample amplifier samples the flyback voltage just before the transformer current drops to zero. Moreover, an offset current is pulled from a detection input of the double sample amplifier in order to generate a more accurate DC output voltage. The offset current is generated in response to the temperature in order to compensate for temperature-induced voltage fluctuations across the output rectifier. Ultimately, in order to maintain a constant output current, the PWM controller modulates the switching frequency in response to the output voltage.

A method of controlling a current command by comparing voltage with a set value needs to vary the set value depending on voltage fluctuation, which involves taking a complicated control. A vector controller for a permanent-magnet synchronous electric motor, according to the present invention, can realize with a simplified configuration a field-weakening operation in a one-pulse mode in a high speed range by providing a current command compensator that corrects a current command by a corrected current command calculated based on a modulation index.

A droop control system for grid-connected synchronization connects to a plurality of distributed power generation modules and a utility grid system. The droop control system includes a detection processing module and a plurality of regulation control modules corresponding to the distributed power generation modules. The detection processing module is coupled with the distributed power generation modules and utility grid system in parallel to obtain a voltage difference, a phase angle difference and a frequency difference. The regulation control modules perform droop control of real power-frequency variety and reactive power-voltage variety and phase angle compensation. Through reactive power-voltage variety droop control approach, impact of impedance alterations in the power system can be eliminated and voltage fluctuations can also be minimized to achieve stable effect. Hence electric power of the utility grid system and distributed power generation modules can be regulated synchronously.

The invention discloses a submodule grouped voltage-sharing control method for a modular multi-level current converter, and belongs to the technical field of power transmission and distribution. According to the technical scheme, the method comprises the following steps: performing average grouping on submodules according to the number of bridge arm submodules, and acquiring voltage values of each group of submodules; calculating total voltage of each group, a bridge arm voltage sum and energy balance factors of each group, obtaining the number of submodules to be switched according to a modulation strategy, and calculating the number of submodules to be switched of each group; and finally, sequencing each group of submodules according to the voltage values, and switching each group of submodules according to the number of submodules to be switched of each group. The method has the beneficial effects that on the premise that the current converter runs normally, an energy balance factor is introduced, and the bridge arm submodules are subjected to a grouped voltage-sharing strategy, so that the aims of increasing the capacitance and voltage sequencing speed of the submodules, balancing energy between the modules and improving the capacitance and voltage fluctuation situation of the submodules can be fulfilled.

A multichannel neurostimulation device spatially spreads the excitation pattern in the target neural tissue by either: (1) rapid sequential stimulation of a small group of electrodes, or (2) simultaneously stimulating a small group of electrodes. Such multi-electrode stimulation stimulates a greater number of neurons in a synchronous manner, thereby increasing the amplitude of the extra-cellular voltage fluctuation and facilitating its recording. The electrical stimuli are applied simultaneously (or sequentially at a rapid rate) on selected small groups of electrodes while monitoring the evoked compound action potential (ECAP) on a nearby electrode. The presence of an observable ECAP not only validates operation of the implant device at a time when the patient may be unconscious or otherwise unable to provide subjective feedback, but also provides a way for the magnitude of the observed ECAP to be recorded as a function of the amplitude of the applied stimulus. From this data, a safe, efficacious and comfortable threshold level can be obtained which may be used thereafter as the initial setting of the stimulation parameters of the neurostimulation device, or to guide the setting of the stimulation parameters of the neurostimulation device.

A wireless mesh network is configured to manage a power grid. Each node within the wireless mesh network is configured to detect and classify voltage fluctuations in power supplied by an upstream transformer coupled to the power grid. When a given node detects a particular type of fluctuation (i.e., an “event”), the node generates a timestamped event classification that reflects the type of event and a time when the event occurred. A server configured to manage the wireless mesh network receives timestamped event classifications from each node within the wireless mesh network and then performs a time correlation with the received timestamped event classifications to determine which nodes detected similar events. When two or more nodes detected the same event at similar times, the server determines that those nodes are coupled to the same transformer.

An interface device transmits a reactive power command depending on a power system from a voltage regulation device of the power system to a wind power generation apparatus electrically connected to the power system, and the wind power generation apparatus receives the reactive power command. Then, the wind power generation apparatus outputs reactive power according to a value obtained by adding, to a reactive power command, another reactive power command for suppression of voltage fluctuation caused by output power of the wind power generation apparatus.

The invention discloses an optimal pressure equalizing control method of a modular multilevel converter type direct current transmission system. By setting an upper limit and a lower limit on voltage, the pressure equalizing control is mainly carried out on submodules with out-of-limit capacitor voltage, and capacitor voltage sequencing for submodules with no out-of-limit capacitor voltage is processed by combing the charging/discharging conditions of bridge arm current so as to increase the probability of maintaining an original switching state for the submodules with no out-of-limit capacitor voltage when the next action is in triggering control and lower the switching frequency of devices. The introduction of the pressure equalizing control can not lower the working frequency of triggering control and the tracking speed of a converter by using submodule capacitor voltage sequencing and triggering control to work at different frequencies. The optimal pressure equalizing control method of the invention can greatly lower the switching frequency of the devices on the premise of having no obvious increment on submodule capacitor voltage fluctuation.

Disclosed herein are a variety of different electrical system topologies intended to mitigate the impact of large intermittent loads on a 12 volt vehicle power distribution system. In some embodiments the intermittent load is disconnected from the remainder of the system and the voltage supplied to this load is allowed to fluctuate. In other embodiments, the voltage to critical loads is regulated independently of the voltage supplied to the remainder of the system. The different topologies described can be grouped into three categories, each corresponding to a different solution technique. One approach is to regulate the voltage to the critical loads. A second approach is to isolate the intermittent load that causes the drop in system voltage. The third approach is to use a different type of alternator that has a faster response than the conventional Lundell wound field machine.

A power factor correction (PFC) circuit includes an inductor, a diode, a storage capacitor, a switch and a control unit. The input power has a voltage fluctuation V₁. The storage component absorbs a first voltage fluctuation and a switch regulation circuit absorbs a second voltage fluctuation V₂. Thus output voltage from the PFC circuit is not a conventional constant voltage but a voltage of a great ripple. The PFC circuit further has a harmonic regulation unit. The harmonic regulation unit generates a voltage signal containing 3^rd harmonic. The control unit receives a feedback signal and the voltage signal containing 3^rd harmonic to generate a reference to the inductor current. Therefore, the inductor current contains 3^rd harmonic. Thus power fluctuation absorbed and released by the capacitor is smaller. As a result energy storage capacitance can be reduced significantly.

The invention relates to a single-phase universal electric energy quality controller for power supply for electrified railways, and belongs to the technical field of flexible AC power transmission and distribution; the invention comprises a single-phase multi-coil transformer composed of a primary coil and n secondary coils, so that the secondary coils of the transformer can be connected in parallel with n voltage sources of current transformers; n capacitors are connected with n voltage source current transformers, so as to form a single-phase chain-type H-bridge current transformer with n chains; the AC terminal of the H-bridge current transformer is directly connected with the traction grid through a reactor. The invention has the functions of active power control, reactive power compensation and harmonic compensation, so as to resolve three-phase voltage unbalance, voltage fluctuation, low power factor and harmonic pollution and so on that exist in ER traction transformer stations, effectively lower the capacity of traction transformers, increase ER transport capacity and transportation capability. Moreover, the invention is characterized in small occupied area, little loss and low cost, in order to gain perfect harmonic suppression characteristics and dynamic response features, and provide convenience in industrial production and improve device reliability.

A desired value of reactive power flow between a to-be-controlled power system and an adjoining power system is determined according to measured values of the reactive power flow and an effective power flow and desired voltage values of the to-be-controlled power system and of the adjoining power system. Thereafter, a required value of a reactive power of the to-be-controlled power system is calculated according to the desired value of the reactive power flow, the measured values of the reactive power flow and the effective power flow, and the desired voltage value and a measured voltage value in the to-be-controlled power system. Thereafter, a control apparatus having an electric capacity near to the required value of the reactive power is selected from control apparatus arranged in the to-be-controlled power system to make the selected control apparatus adjust a voltage of the to-be-controlled power system. Therefore, cooperation of the to-be-controlled power system with the adjoining power system can be performed by collecting locally-existing-information, and a voltage fluctuation and/or a reactive power fluctuation in the to-be-controlled power system can be immediately suppressed.

The invention relates to a modular multi-level converter capacitor voltage fluctuation inhibition method under a low-frequency working condition, and belongs to the technical field of power electronics and motor drive. The method comprises the following steps: the alternating-current side three-phase phase current which meets the low-frequency working need is obtained by performing closed-loop control on the modular multi-level converter alternating-current side three-phase phase current; loop current only contains a direct-current component and a high-frequency alternating-current component by closed-loop control of the three-phase loop current, and a bridge arm voltage contains a high-frequency zero sequence component by overlapping high-frequency voltage at the midpoint electric potential at the direct-current side; the amplitude values, the frequencies and the phases of the loop current high-frequency alternating-current component and the bridge arm voltage high-frequency zero sequence component are obtained by operation, so that the phase voltage and the phase current of the alternating-current side do not contain high-frequency harmonic waves, moreover, the cycles of charging and discharging submodules are shortened, and the effect of inhibiting the capacitor voltage vibration of the submodules is realized; the electrical quantity of each bridge arm is kept to be balanced by the balancing control on the bridge arm energy so as to guarantee that the modular multi-level converter runs symmetrically and stably.

The invention discloses a micro-grid multi-micro-source inverter loop current and voltage fluctuation master-slave control method, which is implemented by a master controller and slave controllers. The master controller comprises a power ring, a voltage ring and a micro-grid current feedforward link. Each slave controller consists of a voltage outer ring and a current inner ring for double-ring control, and can quickly respond to voltage fluctuation caused by switching a distribution network and micro-sources near loads. When a micro-grid system is in a parallel operation mode, the master controller controls the energy output of the micro-sources of the micro-grid by setting rated active power and rated passive power of the micro-grid system, and simultaneously processes real-time voltage and real-time frequency of the distribution network to send control signals to each slave controller, so that inverters output active power and passive power required by the micro-grid system; and the inverters uniformly output voltage synchronous with the distribution network to meet the requirement of synchronization of the micro-grid and the distribution network so as to avoid generating loop current among the micro-sources.