In one embodiment, a viewer executing on an electronic device having a touch sensitive display shows a three-dimensional (3D) model of a building created using computer aided design (CAD) software. A plurality of selectable interface nodes are provided at respective locations within the 3D model. Each interface node is linked to at least one corresponding two-dimensional (2D) construction drawing that shows a section view, a plan view, an elevation view or a detail view of the building related to the location of the interface node. In response to receiving input from a user indicating selection of a particular interface node, a menu is displayed with one or more selectable menu options. In response to receiving additional input from the user indicating selection of a particular menu option, a corresponding 2D construction drawing for the particular interface node is displayed in context of the 3D model of the building.

Generating a digital-media-enhanced electronic record of a locate and/or marking operation performed by a locate technician. The locate and/or marking operation comprises locating and/or identifying, using at least one physical locate mark, a presence or an absence of at least one underground facility within a dig area, wherein at least a portion of the dig area may be excavated or disturbed during excavation activities. A location of the at least one underground facility and/or the at least one physical locate mark is electronically rendered on a display device so as to generate an electronic visual representation of the locate and/or marking operation. At least one digital media file representation of a corresponding digital media file relating to at least one aspect of the locate and/or marking operation or an environment of the dig area is also electronically rendered on the display device, so as to generate a digital-media-annotated representation of the locate and/or marking operation. Information relating to the digital-media-annotated representation of the locate and/or marking operation is electronically transmitted and/or stored so as to generate the digital-media-enhanced electronic record of the locate and/or marking operation.

The present invention discloses a filter for removing noise, which includes: a lower magnetic substrate; a coil layer disposed on the lower magnetic substrate and including at least one conductor pattern and an insulating layer covering the conductor pattern; an upper magnetic substrate disposed on the coil layer; and a magnetic permeability enhancing layer disposed on the magnetic substrate with lower magnetic permeability of the lower magnetic substrate and the upper magnetic substrate. According to the present invention, it is possible to implement a filter for removing noise with high performance, characteristics, and reliability by increasing magnetic permeability to improve impedance characteristics and improving an effect of shielding electromagnetic waves such as jamming.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

A microelectromechanical (MEM) resonator includes a resonant cavity disposed in a first layer of a first solid material disposed on a substrate and a first plurality of reflectors disposed in the first layer in a first direction with respect to the resonant cavity and to each other. Each of the first plurality of reflectors comprises an outer layer of a second solid material and an inner layer of a third solid material. The inner layer of each of the first plurality of reflectors is adjacent in the first direction to the outer layer of each reflector and to either the outer layer of an adjacent reflector or the resonant cavity.

A signal conditioning apparatus can include a coaxial cable having at least one slot formed therein. A conductive film can be applied to the coaxial cable so as to cover each slot. A device mounting surface can be formed within the slot and a protection device can be mounted on the device mounting surface. A housing consisting of one or more interlockable portions can be coupled to the coaxial cable.

An unbalanced-balanced conversion circuit element includes an inductor connected in series between an unbalanced terminal and a first balanced terminal. The first balanced terminal side of the inductor is grounded via a capacitor. A capacitor is connected in series between the unbalanced terminal and a second balanced terminal. An inductor is connected between the first balanced terminal side of the inductor and the second balanced terminal side of the capacitor. In a laminate defining the unbalanced-balanced conversion circuit element, the capacitor is spaced far from a mounting surface of the laminate in comparison with other circuit elements.

A paint dispensing nozzle arrangement for dispensing paint into a paint applicator, the paint applicator having a base plate, an interface material to allow the paint to adhere to the base plate, and a removable paint mold, the nozzle arrangement comprising a dispensing nozzle for dispensing paint into the paint mold, and a displacement member, the displacement member arranged relative to the dispensing nozzle such that the nozzle can dispense paint into the paint mold without coming into contact with the interface material.

A fabric for forming a fibrous paper web having an embossed surface is provided that includes at least longitudinal and transverse threads interwoven with one another in a weave repeat defining a machine side and a paper side. Some of the longitudinal threads form embossing threads having projecting paper side floats on the paper side of the fabric passing over more than one transverse thread. The fabric includes at least a first woven fabric layer forming the paper side on its outside and having longitudinal and transverse first threads interwoven with one another and a second woven fabric layer forming the machine side on its outside and having longitudinal and transverse second threads interwoven with one another. At least some of the longitudinal second threads form embossing threads, which penetrate the first woven fabric layer for forming the paper side floats and connect the two woven fabric layers.

The loom includes a weaving area (18) into which weft threads are inserted into at least one upper channel and one lower channel, each of these weft threads being inserted between at least two warp threads by at least one weft insertion element: first element for focusing on one of these channels and determining the position of the warp threads relative to the weft thread, and second element for inserting at least one binding thread (16) above, between and below these channels. The loom includes at least one element for gripping the at least one binding thread and element for moving the at least one gripping element out of and into the weaving area (18) so as to place the at least one gripping element in contact with the at least one binding thread and to allow the drawing of the at least one binding thread.

Systems and methods for controlling the output of a battery pack are disclosed. In one example, a battery pack contactor is opened in response to battery pack current. The system and method may reduce battery pack degradation and increase system flexibility.

A battery system for a vehicle is provided with discharge circuits (R1, 129A through 129D, 128A through 128D) that discharge battery cells (BC1 through BC4) via measurement lines of those battery cells (BC1 through BC4). A control circuit transmits to an integrated circuit (3A) a first discharge command that causes discharge of the odd numbered battery cells (BC1 and BC3) of a cell group (GB1), a first transmission command that causes transmission to the control circuit of the terminal voltages of only the odd numbered battery cells (BC1 and BC3) measured during execution of the first discharge command, a second discharge command that causes discharge of the even numbered battery cells (BC2 and BC4) of the cell group (GB1), and a second transmission command that causes transmission to the control circuit of the terminal voltages of only the even numbered battery cells (BC2 and BC4) measured during execution of the second discharge command; and, based on the these various terminal voltages transmitted from the integrated circuit (3A), the control circuit diagnoses abnormalities in the system that includes the battery cells, the measurement lines, and the discharge circuits.

A method for charging an assembled battery including series circuits connected in parallel, each of the series circuits including series-connected lead storage batteries, using a single charger is provided. The method includes: a first step of obtaining a first index value, corresponding to a resistance value of a first series circuit with a correlative relationship, the first series circuit having a lowest resistance value; a second step of obtaining a second index value corresponding to a resistance value of a second series circuit with a correlative relationship, the second series circuit having a highest resistance value; a third step of performing normal charging, in which the assembled battery is charged with a first amount of charge corresponding to the first index value; and a fourth step of performing refresh charging, in which the assembled battery is charged with a second amount of charge corresponding to the second index value.

An energy management system has an integration control portion that performs control to charge a storage battery with a power of such an amount that a power consumption including a power supplied by a supply portion is equal to or smaller than a target value indicated by power consumption target information recorded in a recording portion when a power consumption detected by a detection portion is smaller than the target value, and to supply a building with a power with which the storage battery is charged such that the power consumption including the power supplied by the supply portion coincides in amount with a power equal to or smaller than the target value indicated by the power consumption target information recorded in the recording portion when the power consumption detected by the detection portion is larger than the target value.

State based full and empty control for rechargeable batteries that will assure a uniform battery empty condition, even in the presence of a load on the battery. A fuel gauge provides a prediction of the open circuit voltage of the battery, and when the predicted open circuit voltage of the battery reaches the predetermined open circuit voltage of an empty battery, the load is terminated, after which the battery will relax back to the predetermined open circuit voltage of an empty battery. A similar technique is disclosed for battery charging, allowing faster battery charging without overcharging. Preferably an RC battery model is used as the fuel gauge to provide the prediction, but as an alternative, a coulomb counter may be used to provide the prediction, with error correction between successive charge discharge cycles.

A controller for controlling a flow cell battery system is provided. The controller operates the flow cell battery system in a plurality of states including a plating state, a charging state and a discharge state.

Temperature characteristics of battery cells are detected. In accordance with one or more embodiments, an intercept frequency is detected for each battery cell, at which frequency an imaginary part of a plot of impedance values of the battery cell exhibits a zero crossing. The impedance values correspond to current injected into the cell. A temperature of the cell is determined based upon the detected intercept frequency for the cell and stored data that models operation of the cell. Various approaches are implemented with different types of circuits coupled to detect the impedance values of the respective cells.

A charging device with a battery management system which remains a rechargeable battery in full capacity during standby after being fully charged is disclosed. The charging device includes a charging module, electrically connected to a power source, for charging the rechargeable battery; a voltage detecting module, for detecting a voltage of the rechargeable battery; and a determination module, for instructing the charging module to charge the rechargeable battery with a supplementary current, when the voltage of the rechargeable battery detected by the voltage detecting module reduces to a first predetermined voltage, until the voltage of the rechargeable battery reaches a second predetermined voltage. A reduction of the voltage of the rechargeable battery is due to self-discharge of the rechargeable battery during standby after being fully charged.

A method for operating a driverless, mobile assembly and/or material transport unit as a driverless transport system (DTS) with fixed assembly and/or warehousing stations. In this method, a system control device is used for the entire assembly process. The driverless, mobile assembly and/or material transport units comprises a travel device for the traveling movement of the unit, a drive device for the travel device, an energy storage device for providing the energy for the drive device and a control device for controlling the traveling movement in coordination with the system control device.

A system for detecting a short-circuited ultracapacitor cell in a machine is disclosed. The system may have a memory that stores instructions and one or more processors capable of executing the instructions. The one or more processors may be configured to perform cell balancing among ultracapacitor cells arranged within two or more ultracapacitor modules, each ultracapacitor module including at least two ultracapacitor cells connected in series. The one or more processors may be further configured to measure a module voltage generated by each of the plurality of ultracapacitor modules after performing the cell balancing and before applying a load of the machine to the ultracapacitor modules, and determine whether an ultracapacitor cell among the plurality of ultracapacitor cells is short-circuited based on a comparison of the measured module voltages.

Systems and methods to determine cell capacities of a vehicle battery pack. Cell capacities may be determined using state of charge (SOC) estimates for the cells and a charge count for the battery pack. The SOC estimates may be determined when the SOC of the battery pack is below a lower threshold and above an upper threshold. Error values may also be generated for the cell capacity values.

According to an embodiment of the present invention, a recharging device includes a recharging port that receives a flameless candle and recharges a battery in the candle. The recharging device includes a first stacking structure that has a top portion and a bottom portion. There is a top stacking contact on the top portion. An electrical power bus is connected with the top stacking contact. The electrical power bus is also configured to provide electrical power to the flameless candle through the recharging port. The top portion of the first stacking structure is configured to mate with a bottom portion of a first stacking structure of another recharging device.

Systems and methods for in-vehicle charging of pallet jack batteries are provided. An example system allows using a power source of a host vehicle configured to provide power at voltage levels lower than the operating voltage of the pallet jack battery stack. The system may allow, for example, charging a 24 volts pallet jack battery stack from a 12 volts power source of the host vehicle. The system may further comprise an interconnecting circuit having a plurality of contactors electrically coupling the batteries in parallel for charging and serially for discharging. The system may further comprise a voltage monitoring circuit to detect whether the pallet jack is connected to the host vehicle power source for charging. Based on the detection, the voltage monitoring circuit may reconfigure the interconnecting circuit to electrically couple the pallet jack batteries in parallel.

A system for protecting a power consuming circuit, the system comprising two terminals for receiving power and two terminals for providing received power. Between one of the receiving terminals and a providing terminal, a transistor is provided which is controlled by a Zener diode and to break the connection between one of the receiving terminals and a providing terminal, if a voltage over the providing terminals or the receiving terminals exceeds the breakdown voltage of the Zener diode.

A battery system is disclosed. The battery system includes a plurality of battery cells, and a battery cell balancing unit, configured to adjust voltages across each of the battery cells to reduce variation among the voltages across the battery cells. The battery cell balancing unit includes a controller configured to receive a DC reference current and to generate an AC current based on the DC reference current, a transformer, a rectifier circuit including a rectifier connected to the output coil, and a switching unit including a plurality of switches, each configured to selectively connect the rectifier to one of the battery cells.

An electric power supply system includes a connecting device that connects a secondary battery provided in a vehicle to a building, and a control apparatus that i) identifies the type of the vehicle that is connected to the connecting device, the type of the secondary battery, or the type of electric power that is distinguishable by the charging source of the electric power stored in the secondary battery, ii) determines a preset electric power supply method based on the identification results, and iii) controls a supply of electric power from the secondary battery to the building based on the determined electric power supply method.

A method for scheduling a charge of a plug-in electric vehicle (PEV) includes receiving, by a load management system, PEV information from a PEV plugged into an electric vehicle supply equipment (EVSE); transformer information from a transformer management system, the transformer information relating to a transformer associated with the EVSE; determining, by the charging information based on the PEV information and transformer information; providing the charging information to the PEV.

An energy storage system and a method of controlling the same is provided. The energy storage system may directly provide generated DC power or DC power stored in a battery to a DC load without performing a DC/AC conversion or an AC/DC conversion. Furthermore, in the case where a grid operates abnormally (e.g. power interruption) and the energy storage system functions as an uninterruptible power supply (UPS), power stored in a battery may be selectively provided to loads according to power remaining in a battery, and thus stored power may be used stably.

According to some embodiments, battery charge management using a scheduling application is disclosed. A first parameter may be received from a scheduling application running on a mobile computing device having a battery pack. Based on at least the first parameter and battery pack data, a required charge percentage for the battery pack may be determined and the remaining capacity of the battery pack may be determined. If the remaining capacity of the battery pack is less than the required charge percentage, a charge termination voltage may be determined and the battery pack may be charged to the charge termination voltage.

A semiconductor device for battery control includes a CPU, a first bus coupled to the CPU, a second bus not coupled to the CPU, and a protective function circuit for protecting a battery from stress applied thereto. The semiconductor device also includes a non-volatile memory storing trimming data, a trimming circuit to perform trimming required to allow the protective function circuit to exert a protective function, and a bus control circuit capable of selectively coupling the first bus and the second bus to the non-volatile memory. The semiconductor device further includes a transfer logic circuit which causes, by making the bus control circuit select the second bus, a trimming data transfer path leading from the non-volatile memory to the trimming circuit to be formed and the trimming data stored in the non-volatile memory to be transferred to the trimming circuit without involving the CPU.

The invention relates to a monitoring system for monitoring a state of a door lock mechanism of a door or of a closure of a storage space of a means of transportation, comprising a generator and a sensor/actuator. The generator produces electrical energy from vibration energy, and the sensor detects the state of the door lock mechanism. The sensor uses the kinetic energy that is produced by the actuation of the door lock to generate an electrical signal, which is then transmitted to a microcontroller.

A discharge device actively discharges a main capacitor in an electric-power system of an electric-drive vehicle and comprises a discharge branch of a circuit connected in parallel to the capacitor and including a discharge transistor biased to “conduction” mode when the capacitor must be discharged. A control device is connected to a “gate/base” terminal of and controls the transistor, biasing the transistor to the mode when the capacitor is required to fee discharged. A control transistor maintains the discharge transistor in a “non-conductive” state when the control transistor is in the mode. The control transistor is in the state for the discharge transistor to be in the mode. A safety capacitor is interposed between the terminal and a power supply and charges when the discharge transistor is in the mode, causing a progressive decrease of current at the terminal, until the discharge transistor is biased to the state.

An electrical generator includes a stator having fractional-slot concentrated windings and a rotor having field windings. A drive is provided having a circuit to control current flow to the field windings and a controller to input an initial DC field current demand to the circuit to cause the circuit to output an initial DC field current representative of a DC field current demand that would cause an electrical generator having sinusoidal stator windings to output a desired AC power. The controller receives feedback on the magnetic field generated by the initial DC field current, isolates an ideal fundamental component of the magnetic field based on the feedback and to generate a modified DC field current demand, and inputs the modified DC field current demand to the circuit, thereby causing the circuit to output an instantaneous non-sinusoidal current to the field windings to generate a sinusoidal rotating air gap magnetic field.

A wind power generator generates power through a rotation of a rotor and is interconnected, and operated with its power generation output previously limited in order to be able to further supply the power to a power system in response to a decrease in system frequency. Thus, a concentrated control system derives a required restricted amount corresponding to a power generation output required to respond to the decrease in system frequency, derives a value by subtracting an amount corresponding to a latent power generation output with which the power generation output can be increased, from the required restricted amount, and sets a restricted amount of the power generation output in each wind power generator to perform the operation with the power generation output previously limited to respond to the decrease in system frequency, based on the above value.

A generator airgap monitoring system includes a first proximity sensor disposed in a first location of a stator and configured to transmit a first signal representative of a first distance between the first proximity sensor and a plurality of rotor poles of a rotor, and a controller communicatively coupled to the first proximity sensor. The controller is configured to derive a first plurality of instantaneous airgaps based on the first signal and to determine a difference between a first instantaneous airgap of the first plurality of instantaneous airgaps and a second instantaneous airgap of the first plurality of instantaneous airgaps. The first plurality of instantaneous airgaps includes a first plurality of measurements of airgaps between the stator and the plurality of rotor poles when the rotor is rotating. The first instantaneous airgap and the second instantaneous airgaps include measurements for respective rotor poles.

A wind energy plant comprising a rotor having blades and a generator driven by said rotor for generating electric energy. The pitch of the blades can be adjusted and a pitch system for adjusting the pitch angle of the blades is provided, which is supplied by a hub power source. An additional electric load is provided on the hub. A pitch power control device is provided which dynamically distributes the power of the hub power source between the pitch system and the additional electric load and further acts on the pitch system such that its power consumption during high-load operation is reduced. Thus, the power consumption of the pitch system during high-load operation can be reduced and additional power provided for operating the additional load. Even large additional loads, such as a blade heater, can be operated in this way, without having to boost the hub power source.

The control system of this floating wind turbine generator is a control system of a floating wind turbine generator in which the control system controls a pitch angle control section by a pitch angle instruction value calculated on the basis of signals detected by a second sensor detecting a relative angle between a nacelle and a tower and a third sensor detecting a yaw angle from a reference position of the tower so that a signal detected by a first sensor detecting wind direction deviation relative to a vertical direction of a rotation plane of wind turbine blades indicates an angle within a predetermined range from the vertical direction of the rotation plane of the wind turbine blades, and controls a yaw driving device by a yaw driving instruction value calculated on the basis of the signals detected by the second sensor and the third sensor.

A DC chopper comprising a control unit and a power circuit and a DC chopping method for a DFIG (doubly fed induction generator) system are provided. The input terminal of the control unit is coupled to a DC capacitor of a converter to detect a DC voltage. The power circuit includes input terminals, an overvoltage protection module, a rectifier module and output terminals. The overvoltage protection module comprises at least one discharge unit formed from a discharge resistor and a switch element, and the rectifier module is coupled in parallel to the overvoltage protection module. When a grid voltage drops, the control unit outputs a corresponding control signal to drive the switch element to be ON or OFF, and the output terminal of the power circuit absorbs a portion of rotor inrush current, so as to impose over-current protection.

An integrated power system suitable for simultaneously powering marine propulsion and service loads. The system includes: (a) at least one generator configured with at least first and second armature windings configured to output respective first and second alternating current power signals of different voltages, the at least two armature windings positioned within the same stator slots so that they magnetically couple; (b) at least first and second rectifier circuits coupled to said generator to convert said first and second alternating current power signals into first and second direct current power signals; and (c) a first load to which said first direct current power signal is coupled and a second load to which said second direct current power signal is coupled.

An electrical machine includes a stator having a main armature winding, an exciter field winding, and a transformer primary winding. A rotor is operatively connected to rotate relative to the stator, wherein the rotor includes an exciter armature winding operatively connected to the exciter armature winding for field excitation therebetween, a main field winding operatively connected to the main armature winding for field excitation therebetween, and a transformer secondary winding operatively connected to the transformer primary winding to form a rotating transformer. A generator control unit is operatively connected to the main armature winding, exciter field winding, and transformer primary winding to control the main armature and exciter field windings based on excitation in the primary winding received from the transformer secondary winding.

An on-demand electric power system for providing on-demand electric power in remote locations. The on-demand electric power system generally includes a protective housing, an engine-generator within the protective housing, a control switch electrically positioned between the engine-generator and an electric load, and a control unit in communication with the engine-generator and the control switch to control operation of the engine-generator along with electrical power to the electric load. The control unit detects when electrical power is required by an electric load and then first starts the engine-generator. After a period of time, the control unit then closes the control switch to provide electrical power to the electric load.

This invention is directed to a system that generates a sufficient level of electricity through access to a municipal water supply line to run a furnace during below freezing temperatures. The system includes an inlet that draws water from a water supply line. A first conduit, in communication with the inlet, transports the water into a DC generator that includes an impeller to generate electricity. Water is then routed through a second conduit which then returns the water to the water supply line through an outlet. A solenoid valve may be positioned between the inlet and first conduit which remains closed when the electric grid runs normally but will open during a power outage to supply water to the DC generator. A lithium battery stores power created by the DC generator, which may include a voltage regulator and inverter to convert to DC.

Systems and methods for monitoring excitation of a generator based on a faulty status of a generator breaker are provided. According to one embodiment, a system may include a controller and a processor communicatively coupled to the controller. The processor may be configured to receive, from a contact associated with a generator breaker, a reported status of the generator breaker, receive operational data associated with one or more parameters of a generator associated with the generator breaker, and correlate the reported status of the generator breaker and the operational data. Based on the correlation, the processor may establish an actual status of the generator breaker, and, based on the actual status, selectively modify a mode of excitation of the generator.

A temperature detection device that detects a temperature of a rotor of a motor. The temperature detection device has a current detection unit configured to detect a current value of a current flowing through a winding with which any one of a stator and the rotor of the motor is provided, an iron loss estimation unit configured to estimate an iron loss of the rotor using the current value, and a rotor temperature estimation unit configured to estimate the temperature of the rotor using the iron loss.

According to an embodiment, a method of operating a wind turbine comprising a DC-to-AC voltage converter is provided, the wind turbine being connectable to a grid via the DC-to-AC voltage converter, the method comprising: determining a line voltage of a power line connecting the DC-to-AC voltage converter to the grid; if the determined line voltage exceeds a predefined voltage threshold value, injecting reactive current into the power line, wherein the amount of reactive current injected is chosen such that an output voltage of the DC-to-AC voltage converter is kept within a predetermined voltage range.

A generator includes a permanent magnet generator, an exciter and a main generator mounted for rotation on a shaft. The main generator is configured to produce a voltage output. A generator control unit includes a circuit configured to provide current from the permanent magnet generator to the exciter. A switch is provided in the circuit and is configured to change between open and closed conditions. The switch is configured to flow current in the circuit in the closed condition and interrupt current flow in the open condition. An overvoltage limit controller is programmed to determine an amount of overvoltage of the output voltage exceeding a desired voltage. Either a fixed reference threshold is used or a reference threshold voltage is calculated based upon the duration in over voltage condition, and the switch is modulated between the open and closed conditions according to error between the actual output voltage and the reference threshold voltage to limit the output voltage to the desired reference threshold voltage.

A DC motor assembly (10) with soft starting capability is provided. The assembly (10) comprises a DC motor (12) including an armature (14) and a field winding (16) adapted to be excited separately from the armature; and circuitry configured to controllably increase current flow through the field winding of the DC motor as a function of time during starting of the DC motor.

A power supply system for a motor vehicle includes a generator that includes a rotor having a field coil and a stator having an armature coil; a rectifier that rectifies AC power generated in the armature coil; an excitation control circuit that takes control of a voltage applied to the field coil; a capacitor that is connected to the DC side of the rectifier, and receives and transfers the rectified power; a battery connected to an electric load of the motor vehicle; a DC-DC converter that is connected between the capacitor and the battery and capable of converting unidirectionally or bidirectionally an input DC voltage into any DC voltage; and a selection switch which connects the capacitor or the battery to the excitation control circuit as a power supply source.

The regulator/brush-holder assembly (1) comprises a support (2) and an electrical circuit (5, 6) comprising a regulating element (5) connected by microwires to a trace circuit (6). The electrical circuit further includes a filtering circuit (10) separate from the regulating element and connected by microwires to the trace circuit. According to one particular embodiment, the filtering circuit comprises an insulating substrate (11) and surface-mounted components (C1, C2, S1, S2, V). A ground plane (19) and/or one or more ground pads may be provided for connection to a ground trace of the trace circuit. The filtration frequencies of the filter circuit extend from 100 kHz to 1 GHz.

A method of operating a converter of a wind turbine for providing electric energy to a utility grid includes determining a grid voltage. If the grid voltage is between a nominal voltage and a first voltage threshold, i.e. higher than the nominal voltage, a normal procedure for lowering the grid voltage is performed. If the grid voltage is above the first voltage threshold, another procedure for keeping the wind turbine connected is performed, wherein the other procedure is different from the normal procedure. Further a corresponding arrangement is described.