Abstract: Methods and systems for controlling a circuit designed to protect electrical equipment, in particular sensitive power grid equipment such as transformers, are disclosed. In particular, methods of local and remote control of operation of protection circuits are provided that allow for remote access to change an operational mode of such protection circuits, while ensuring that power grid equipment is protected locally regardless of any configuration instructions received from a remote or centralized facility. Override levels may be set to ensure power grid transformer protection, regardless of operational mode or remote instruction.

Abstract: This disclosure relates to monitoring operational parameters of a distribution transformer and an associated surge arrester, and methods of retrofitting the distribution transformer with a transformer parameter monitoring (TPM) system. The TPM system can include a plurality of sensors. A subset of the plurality of sensors can be configured to monitor one or more physical properties of a distribution transformer, and another subset of the plurality of sensors can be configured to monitor a surge arrester associated with the distribution transformer. The TPM system can further include a controller that can be configured to receive captured sensor data from the plurality of sensors, and a communications interface that can be configured to communicate the captured sensor data to a remote system for evaluation thereof to determine one or more operational parameters of the distribution transformer and an amount of deterioration of the surge arrester.

Abstract: Systems and method for automated self-testing of a protective device for a transformer are disclosed. One system includes a protection circuit electrically connected to a transformer neutral, the transformer electrically connected to a power grid, the protection circuit may include a DC blocking component, a switch assembly, and a spark gap assembly each positioned in parallel between the transformer neutral and ground, a switch assembly. The system may further include various testing circuits configured within the protection circuit and switches which when actuated inject a signal to test various components in the protective device.

Abstract: A timing leakage protection circuit and a device containing the same. The timing leakage protection circuit includes a sensing unit, a switching unit, a ground fault circuit interrupter (GFCI) control unit, a switching control unit and an adjustable timing unit. The sensing unit and switching unit are used to be connected in series in a circuit to be protected. The switching control unit is configured to receive a control signal output by the GFCI control unit and control the switching unit to be open when receiving the control signal, so as to interrupt a circuit to be protected. Compared to the traditional leakage protection circuit, the circuit provided herein further has a timing function, so that the timing period can be controlled correspondingly according to different voltages, thereby reducing the circuit complexity and cost.

Abstract: A protection circuit is for a medium voltage or high voltage transformer and includes a sensing device, a measurement device, and a switching device. The sensing device is configured to be connected between a primary winding of a voltage transformer and ground potential. The measurement device is connected to the sensing device and the measurement device is configured to measure at least one parameter sensed by the sensing device. The protection circuit is configured to analyse the measured at least one parameter sensed by the sensing device. The protection circuit is configured to generate a trip signal based on the analysis of the measured at least one parameter sensed by the sensing device. The switching device is configured to receive the generated trip signal and disconnect the voltage transformer from a high voltage potential.

Abstract: Systems and methods are provided for continuously and automatically monitoring, controlling, and combining shore-based AC power sources for waterborne vessels while the vessels are at dock or in port. The systems can allow a one or more shore AC power AC to power the entire vessel, and automatically and safely join multiple power sources to power a single higher-current-capacity electrical distribution bus on the vessel. The systems can automatically monitor and evaluate the characteristics of multiple shore power sources to determine when it is possible to safely combine the sources. Also, the systems can recognize the disconnection/disablement of a shore power source, and can un-combine that power source from the other power sources feeding the system. The systems can automatically evaluate the phase, current and voltage of multiple AC sources, and combine the sources only after a specific set of conditions are satisfied.

Abstract: Aspects of this disclosure relate to detecting and recording information associated with electrical overstress (EOS) events, such as electrostatic discharge (ESD) events. For example, in one embodiment, an apparatus includes an electrical overstress protection device, a detection circuit configured to detect an occurrence of the EOS event, and a memory configured to store information indicative of the EOS event.

Abstract: A system and apparatus for detecting and handling circuit faults in a field loop circuit of an industrial safety system is disclosed. The field loop circuit extends from the emergency shutdown device of the system to an instrument switch and back to an ESD input. The monitoring circuit is installed in the field loop circuit at the edge between the control and field sides of the system and is configured to detect high current events in the field loop, as distinguished from circuit conditions caused by instrument switches. If a high current event occurs, the monitoring circuit is configured to immediately isolate the field-side loop and close the control-side of the circuit by recycling a 24 VDC signal back to the monitored input of the ESD. The monitoring circuit is further configured to initiate an alarm to alert operators of the issue.

Abstract: A fast-operating AC fault current limiter, to limit the fault current let through to downstream equipment during short circuit or low-impedance faults, comprises a series inductor to limit current rise time, a current sensor to sense the instantaneous current, a series AC semiconductor switch to interrupt current flow when it exceeds the maximum desired fault current, and a shunt AC semiconductor switch to catch inductor flyback voltage when the series semiconductor switch is opened. Each of the series and the shunt AC switches comprises two back-to-back MOSFETs. Inventive control of timing of the individual MOSFETs obviates the need for exact simultaneous timing of opening the series switch and closing the shunt switch, which is otherwise required to avoid short circuits.

Abstract: Methods, systems, and apparatuses are disclosed for reducing geomagnetically-induced currents. The method includes connecting a plurality of switching devices at a neutral grounding connection point of at least one transformer bank. In a system having two terminals, the method includes grounding one transformer bank through a switch so as to reduce geomagnetically induced current. In a system having more than two terminals, the method includes grounding transformer banks through multiple switches, where the reduction is performed independently for each transformer bank. The method further involves determining a switching frequency and a duty cycle based on an evaluation of factors including effectiveness and fault current detection.

Abstract: A control device for an electrical protection circuit for use in an alternating current system including a transformer is disclosed. An example system includes a first measurement probe, a second measurement probe configured to measure an electrical property within the electrical protection circuit, and a control module, including a processing device. The control module is configured to monitor a measurement from the first measurement probe and transmit a protection activation control signal to the switch assembly based on the measurement from the first measurement probe exceeding a first predetermined threshold. The control module is also configured to monitor a measurement from the second measurement probe and transmit a protection deactivation control signal to the switch assembly based on the measurement from the second measurement probe satisfying a second predetermined threshold.

Abstract: Systems, devices, and methods for a transformer including: a first drive winding (206) wound on a first core; a second drive winding wound on a second core; a sense winding wound across the first and second cores; and a compensation winding wound across the first and second cores; where one or more utility lines are threaded through a middle of the first and second cores, a common mode current in the one or more utility lines causes one or more pulses to appear on the sense winding, a current on the compensation winding is adjusted until the one or more pulses on the sense winding are cancelled out, and the common mode current on the one or more utility lines is the adjusted current on the compensation winding multiplied by a turn ratio between the compensation winding and the sense winding.

Abstract: A disconnection detector includes: a plurality of energizing circuits that supply a constant current from a direct current power supply to a plurality of loads through resistor elements, respectively, the resistor elements each having a predetermined resistance value; a plurality of voltage detectors that are respectively arranged at the plurality of energizing circuits, and that are respectively configured to detect a voltage of a corresponding one of the resistor elements at a load side; and a control circuit that determines, for each of the plurality of energizing circuits, a disconnected state of an energizing path to a corresponding one of the plurality of loads, based on voltages respectively detected by the plurality of voltage detectors.

Abstract: The invention discloses a method for identifying full parameters of an electric element by a fault recording data, comprising steps: inputting fault recording data related to an electric element; conducting data processing on the fault recording data; identifying full parameters of the element by intercepted data and a differential equation of the full parameters of the element; and outputting an identified result. Further proposed are a system for identifying full parameters of a power generator by fault recording data and a method for locating a line fault point with fault recording data. With the implementation of the invention, a fault resistance and full parameters of an element such as an electric line and a transformer, etc. can be identified. The invention can obtain full parameters of a fault element and also a non-fault element, and the parameters precision would be increased from the current 20% to less than 1%.

Abstract: A control device for an electrical protection circuit for use in an alternating current system including a transformer is disclosed. An example system includes a first measurement probe, a second measurement probe configured to measure an electrical property within the electrical protection circuit, and a control module, including a processing device. The control module is configured to monitor a measurement from the first measurement probe and transmit a protection activation control signal to the switch assembly based on the measurement from the first measurement probe exceeding a first predetermined threshold. The control module is also configured to monitor a measurement from the second measurement probe and transmit a protection deactivation control signal to the switch assembly based on the measurement from the second measurement probe satisfying a second predetermined threshold.

Abstract: A magnetic integrated device is disclosed, the device includes: a first magnetic core base and a second magnetic core base that are parallel and a first magnetic core column, a second magnetic core column, and a third magnetic core column that are located between the first magnetic core base and the second magnetic core base; and a first winding, a second winding, and a third winding are wound on the first magnetic core column, the second magnetic core column, and the third magnetic core column respectively in a same manner to form a closed magnetic flux loop, where the first winding, the second winding, and the third winding are separately used for connecting to a branch of a three-phase parallel circuit, and in all branches of the three-phase parallel circuit, values of currents are the same, and a difference between each two current phases is 120 degrees.

Abstract: According to one embodiment, an excitation inrush current suppressing apparatus comprising: bus voltage measurement equipment which measures each phase voltage of the single-phase AC-side bus; transformer voltage measurement equipment which measures a single-phase-side voltage of the transformer; phase detector which detects a cutoff phase when opening the circuit breaker by monitoring each phase voltage measured by the bus voltage measurement equipment and the single-phase-side voltage measured by the transformer voltage measurement equipment, holds the detected cutoff phase, and outputs the same phase as the held cutoff phase; and close command output device which closes the circuit breaker by the same voltage phase as the cutoff phase output from the phase detector.

Abstract: A magnetic core for a transformer, which includes a closed ring with a thick part and a thin part. The thin part is magnetically saturated before the thick part when excited by the same increasing magnetic fields. The thin part only operates briefly at or near first quadrant saturation point or a third quadrant saturation point and, for the rest of the time, it operates in a state between the first quadrant saturation point and the third quadrant saturation point. The present invention overcomes the drawbacks of the conventional magnetic core for a self-excitation push-pull type converter, and significantly improves the efficiency of the converter when it is under a light load, and further improves its efficiency while under a rated load. As the number of turns of the coil on the magnetic saturation transformer is reduced, the working frequency of the converter is improved while still keeping the loss low.

Abstract: Systems and methods for selectively extracting hydrogen gas dissolved in oil are provided. In one embodiment, a system includes a selectively permeable membrane provided at a point of contact between oil and a sensor chamber. The selectively permeable membrane has a hydrogen specificity and a thickness selected to minimize detection of further gasses dissolved in the oil by a hydrogen gas sensor cross-sensitive to the further gasses. The selectively permeable membrane can include polyimide. The further gasses include carbon monoxide, acetylene, and ethylene. The system can include a further membrane and a porous metal disc. The porous metal disc is bound to the selectively permeable membrane by using the further membrane as an adhesive layer and by applying pressure and temperature. The porous metal disc supports the selectively permeable membrane and the further membrane against pressure of the oil when exposed to a vacuum. The further membrane includes fluorohydrocarbons.

Abstract: A power distribution system is dynamically and adaptively configured in real-time to improve energy efficiency, reliability and power quality, particularly if the system includes renewable sources and storages. An optimal multi-objective scheduling and partitioning method is provided to partition the system into self-sufficient sections (SSS) through optimally combination of adjacent basic switching sections (BSS). The SSSs enable system operating at a lower cost, with less power losses, more energy efficiency, improved power quality, and sufficient transient security. The method uses two storage based transient security indices, storage compensation power margin (SCPM) and storage compensation energy margin (SCEM) evaluate the transient stability margin of distribution system. A minimal stability margin is used to ensure that the system remains stable when subject to large unexpected load deviations.

Abstract: An apparatus may include one or more registers configured to store a plurality of values, and an analog-to-digital converter (ADC). Each value of the plurality of values may correspond to a characteristic of a transistor at a respective temperature value. The ADC may be configured to generate a digital value corresponding to a difference in voltage levels between a first terminal and a second terminal of the transistor. The apparatus may further include a sensor configured to measure a temperature, and control logic configured to generate a first voltage level at a control terminal of the transistor and receive the digital value from the ADC. The control logic may be further configured to determine, during a first operational mode, a current passing through the transistor dependent upon the digital value, at least one value of the plurality of values, and the temperature.

Abstract: According to one embodiment, an excitation inrush current suppression device for suppressing excitation inrush currents flowing through a breaker of the three-phase collective operation type for opening and closing connection is configured to measure a three-phase AC voltage of the power supply bus bar to calculate prospective magnetic fluxes of the transformer, and to measure a three-phase AC voltage on the transformer side to calculate residual magnetic fluxes of the transformer after shutoff, so as to set the breaker closed when polarities of the prospective magnetic fluxes respectively agree with polarities of the residual magnetic fluxes in all of the phases respectively.

Abstract: A reaction mode is selected through a user interface from a plurality of reaction modes that includes a fast reaction mode, by which each of a plurality of values assigned to a process variable over time are individually evaluated in an event decision that asserts an occurrence of a power event. The reaction modes also include a slow reaction mode by which none of the values assigned to the process variable over time are individually evaluated in the event decision. Measurements of a signal monitored by a power controller are assigned to the process variable as its values. The event decision evaluates the process variable values against an event boundary in accordance with the selected reaction mode. A transition between conducting and non-conducting states in a switch circuit is compelled in response to the occurrence of the power event as determined from the event decision.

Abstract: Systems and methods for adaptive distance protection are provided. An adaptive ground distance protection system may be installed in a power system to provide an accurate measurement of the apparent impedance of the transmission lines thereby ensuring reliable and stable operations of the power system. The potential of a system ground in reference to the remote earth is measured and used in calculating the apparent impedance of a transmission line. An accurate assessment of the apparent impedance of a transmission line is therefore provided and reduces the risk of misoperation of relays. Existing protection systems of a power system may be augmented, for example, via a retrofitting process, to enhance reliability of the power system, reduce costs, reduce customer service interruption, and expand opportunities for deployment.

Abstract: According to one embodiment, an excitation inrush current suppressing apparatus comprising: bus voltage measurement equipment which measures each phase voltage of the single-phase AC-side bus; transformer voltage measurement equipment which measures a single-phase-side voltage of the transformer; phase detector which detects a cutoff phase when opening the circuit breaker by monitoring each phase voltage measured by the bus voltage measurement equipment and the single-phase-side voltage measured by the transformer voltage measurement equipment, holds the detected cutoff phase, and outputs the same phase as the held cutoff phase; and close command output device which closes the circuit breaker by the same voltage phase as the cutoff phase output from the phase detector.

Abstract: A device for mitigating Geomagnetically Ground Induced Currents (GIC) flowing from the neutral of a star-connected three-phase power transformer to ground without compromising its basic insulation, operation or integrity. Resistor (R10), of an adaptive non-linear negative volt-ampere characteristic is inserted, from the transformer neutral (N) to ground (G), by opening the ground switch (S1) depending on its DC flow magnitude. Such an insertion to render said induced currents, for any given GMD severity, blocked and inconsequential to the equipment because of (R10) very large resistance prevailing at that condition.

Abstract: The present invention provides a system and computer program product for implementing a smart transformer, comprising a processor, and a balancing algorithm residing on the processor, wherein the balancing algorithm is stored on a non-transitory computer readable medium having computer executable program code embodied thereon, the computer executable program code configured to cause the system to monitor and control an electric customer load and generation in order to optimize the performance of a distribution transformer, wherein the processor receives a plurality of system inputs and uses the balancing algorithm to determine a rating of the transformer and an amount of customer load.

Abstract: A protective system far a power transformer having a neutral line connected to ground where large currents can flow in the neutral line due to electro-magnetic disturbances. The system includes circuitry for: (a) sensing the current level in the neutral line and whether it exceeds a predetermined threshold for a predetermined period; and (b) sensing and processing the harmonic content of the load current and determining the existence of certain relationships of the “even” and “odd” harmonics. Signals, including alarms, indicative of excessive conditions are produced. The system may also include circuitry for sensing the load current level and generating a signal alarm if the load level is above a given value when the harmonics and the DC current have values in excess of certain predetermined values.

Abstract: The present disclosure provides systems and methods for calculating the flux in a core of an unloaded power transformer using current measurements taken from a capacitance-coupled voltage transformer (CCVT) attached to the same phase line as the power transformer. According to various embodiments, the current sensors may both be positioned at zero-voltage points in the CCVT, eliminating the need for high-voltage insulated current sensors. An intelligent electronic device (IED) may determine the magnetic flux within the core of the power transformer using the measured and/or derived currents through capacitive assemblies of the CCVT. The IED may calculate the residual flux in the power transformer when it is de-energized. The IED may use the calculated residual flux to facilitate an optimized re-energization of the power transformer, thereby reducing inrush currents during re-energization.

Abstract: A system for reducing inrush current in a three phase utility transformer upon energization of the transformer by an applied three phase voltage utilizes a pre-flux circuit for establishing residual flux levels in the core segments of the primary windings of the transformer which are near the prospective flux levels established in the core segments by the applied voltage. The pre-flux circuit includes a pre-fluxing capacitor which, after being charged to a predetermined voltage level, is discharged serially through two of the primary windings to establish the predetermined flux levels in the core segments of the two windings, and a reduced flux level in the core segment of the remaining primary winding. The transformer is energized at the instant of positively-referenced peak phase voltage to the third primary winding such that prospective and residual flux approach a near-equal level in all three core segments and inrush current is reduced.

Abstract: The present invention provides a direct-current current transformer, or DCCT, yielding bandwidth from DC to several MHz. The DCCT according to this invention is a simple, open-loop, device in which flux densities occur at very low levels, avoiding difficulties occasioned by core saturation.

Abstract: A method for operating a converter circuit is provided. The converter circuit includes a converter unit and a transformer. The transformer includes at least one winding set with a primary winding and a secondary winding. The converter unit is connected, on the AC voltage side, to the primary winding of the respective winding set. In order to compensate for undesirable saturation of the transformer, the converter unit is used to deliberately apply a DC voltage to the primary winding of the respective winding set of the transformer.

Abstract: A current transformer configuration includes a primary part and a secondary part. The primary part is surrounded by a housing. The housing has a first conductive housing part and a second conductive housing part. An electrically insulating gap lies between the two conductive housing parts. The housing passes through the secondary part. The electrically insulating gap is bridged by a surge protection configuration.

Abstract: A transformer assembly is described. Embodiments of the transformer assembly are adapted to facile disconnection and removal of a transformer from the transformer assembly without disconnecting service lines from the transformer assembly. Moreover, embodiments of the transformer assembly are adapted to de-energize the transformer without interrupting primary power to downstream devices, and to safely and easily park energized or de-energized connectors such as loadbreak elbows during transformer maintenance. Methods of using the transformer assembly are also described.

Abstract: A disconnector for distribution transformers with dielectric liquid intended for comprehensive protection of a power grid or for protecting distribution transformers. The disconnector provides at least two cylindrical current-limiting fuses located inside a transformer tank. Each fuse is electrically connected with an external phase power supply through fixed contacts and moving contacts of the disconnector with the active part of the transformer. The disconnector has an additional auxiliary contact which is electrically connected to a switch connected to the active part of the transformer on a low voltage side of the transformer.

Abstract: According to one embodiment, there is provided a magnetizing inrush current suppression device. A closing phase determination unit determines a phase position for suppressing the magnetizing inrush current among phase positions in which the prospective magnetic flux calculated by the prospective magnetic flux calculation unit and the residual magnetic flux calculated by the residual magnetic flux calculation unit coincide between the lines of the minimum residual magnetic flux determined by the minimum residual magnetic flux determination unit, as a closing phase position. A closing unit simultaneously closes the three phases of the circuit-breaker at the determined closing phase position.

Abstract: An electrical current transformer for installation upon a power distribution line including a generally annular, split core and a secondary winding. The secondary winding includes a first winding portion, wound with a first winding polarity about the split core, and a second winding portion, wound with a second, opposite winding polarity about the split core, and a tap. The transformer further includes first and second rectifiers, electrically connecting a tap output to terminals of the first and second winding portion opposite the tap, respectively, and a tap control for controlling the tap output, where the tap is both electrically connectable to the output to provide an additive connection and electrically isolatable from the output to cause a subtractive connection. The tap control controls the tap output in response to a condition sensed in the powered circuit. Self-cancellation may be achieved by using windings having an equal number of turns.

Abstract: Several embodiments of a novel technique for limiting transmission of fault current are disclosed. Current power distribution systems typically have an impedance, or reactor, on the output of the network equipment to limit current in the case of a fault condition. A low resistance switch, which changes its resistance in the presence of high current, is connected in parallel with this reactor. Thus, in normal operation, the current from the power generator bypasses the reactor, thereby minimizing power loss. However, in the presence of a fault, the resistance of the switch increases, forcing the current to pass through the reactor, thereby limiting the fault current.

Abstract: An energy monitoring system for a power conductor includes a base unit; a sensor cable; and a current transformer electrically connected to the base unit by the sensor cable. The current transformer includes a secondary winding inductively coupled to the power conductor and a clamping circuit electrically connected in parallel with the secondary winding. The clamping circuit is structured to clamp a voltage across the secondary winding when the voltage across the secondary winding is greater than a predetermined value. An indicator circuit is electrically connected in series with the clamping circuit to indicate when the clamping circuit is actively clamping the voltage.

Abstract: An electronic system to discharge a transformer in case of a failure during a charging phase of the transformer. The system includes the transformer having a primary winding with a first terminal connected to a battery voltage and with a second terminal for generating a primary voltage signal, includes a switch serially connected to the primary winding and having a control terminal carrying a control voltage signal for opening or closing the switch and includes an electronic circuit. The electronic circuit further includes a current generator and a voltage clamping.

Abstract: Systems and method for detecting potentially harmful harmonic and direct current signals at a transformer are disclosed. One system includes a protection circuit electrically connected to a transformer neutral, the transformer electrically connected to a power grid, the protection circuit including a DC blocking component positioned between the transformer neutral and ground and one or more switches selectively actuated to form a path between the transformer neutral and ground in the event of unwanted DC current at the transformer neutral. The system also includes a control circuit electrically connected to the protection circuit and positioned to selectively actuate the switches based on observed conditions within the protection circuit. The system further includes a plurality of test connections disposed within the protection circuit and useable to test electrical properties of the protection circuit.

Abstract: Transformer differential protection is provided by measuring a plurality of currents corresponding to a first set of windings and a second set of windings of a transformer, and compensating the currents based on their respective flows through either the first set of windings or the second set of windings. The compensated currents may be intentionally augmented to compensate for magnetizing inrush and/or stationary overexcitation conditions associated with the transformer. Augmentation based on stationary overexcitation, for example, may be based on either harmonic restraint or an addition of a V/Hz ratio to a restraining signal. A complex current ratio is calculated corresponding to the plurality of compensated currents. The complex current ratio may be based on a two-terminal equivalent power apparatus. Then, an alpha plane analysis is applied to the complex current ratio. Based on the alpha plane analysis, a power apparatus that includes the transformer is selectively tripped.

Abstract: A protected electrical power system may comprise a feeder between a power source and an electrical load. A first current transformer may be positioned on the feeder in a first location. The first current transformer may have a shunt resistor electrically connected across its winding. A second current transformer may be positioned at a second location on the feeder. A control unit may be interposed between the first and second current transformers and may be interconnected with the first and second current transformers on current-monitoring loops independent from the feeder. The control unit may be responsive to a predetermined differential in feeder (DF) current between the first and second current transformers to disconnect the power source from the electrical load. The control unit may have a compensation network for reducing DF error resulting from presence of the shunt resistor in the first current transformer.

Abstract: Systems and method for detecting potentially harmful harmonic and direct current signals at a transformer are disclosed. One such system includes a plurality of detection components electrically connected to electrical signal lines leading from one or more connection points on a power grid, and a plurality of threshold detectors, each threshold detector configured to compare an incoming signal from a detection component to a predetermined signal having a threshold. The system also includes a controller receiving an output from each of the plurality of threshold detectors and configured to drive at least one external component in response to receiving an indication from at least one of the plurality of threshold detectors of a detected signal above a threshold.

Abstract: A three phase transformer circuit is provided that includes a supply side, wherein the supply side is selectably configurable, via the use of sets of terminal boards, between a delta connection and a wye connection at a time of use and, a load side, wherein the load side is selectably configurable between a delta connection and a wye connection at the time of use. The three-phase transformer also provides for selecting an input voltage, from multiple input voltages, via the sets of terminal boards, at the time of use, and for selecting an output voltage for the supply side, from multiple output voltage, at the time of use.

Abstract: The present invention relates to a transformer substation (6) comprising high-voltage switchgear (1), a low-voltage switchboard (3) and a transformer (2) which are electrically interconnected on the upper cover (5) of the transformer (2) through a shielded direct single-pole connection. The high-voltage electric connection (4) is carried out by means of a connection device (8) which, in combination with a control/protection device (10), allows carrying out the safe and integral protection of people and property against possible malfunctions in the transformer substation (6), limiting said malfunctions and preventing disturbances of the high-voltage and low-voltage network.

Abstract: A transformer failure analysis system using a programmable chip in conjunction with a shock response spectrum analysis method to distinguish inrush current and fault current of a transformer and to monitor the phase of an AC power source inputting to the transformer by a phase detector. When an inrush current occurs, the programmable chip provides a control signal to delay the phase of the AC power source being inputted into the transformer, thereby suppressing the occurrence of the inrush current. When a fault current occurs, the control signal cuts off the AC power source from the transformer until the operator has tested the whole circuit architecture to debug and correct circuit application and eliminated the internal fault.

Abstract: According to one embodiment, there is provided a magnetizing inrush current suppression apparatus including an interrupting phase detection unit that detects a phase when the transformer that converts a three-phase alternating-current voltage to a single-phase alternating-current voltage is disconnected, a single-phase alternating-current voltage measurement unit that measures the single-phase alternating-current voltage on the power system side of the circuit breaker, and a closing unit that closes the circuit breaker in the detected phase, based on the measured single-phase alternating-current voltage.

Abstract: According to one embodiment, there is provided a magnetizing inrush current suppression apparatus including a transformer-side voltage measuring unit measuring a single-phase voltage, a conversion unit converting the single-phase voltage to a three-phase voltage, a residual magnetic flux calculation unit calculating residual magnetic fluxes, a voltage measuring unit measuring a voltage on the power source side, a steady magnetic flux calculation unit calculating steady magnetic fluxes, a phase determination unit determining a phase in which polarities of the steady magnetic fluxes match polarities of the residual magnetic fluxes, and a closing unit closing the circuit breaker in the phase.

Abstract: An overvoltage protection device for protecting a wind turbine against overvoltage is provided. The overvoltage protection device includes an electrical transformer for transforming electrical power generated by a wind turbine generator from a low-voltage region to a medium-voltage region. The electrical transformer includes at least one secondary winding electrically connected to the generator of the wind turbine, at least one primary winding electrically connected to an electrical utility grid receiving the generated electrical power, and at least one counter-winding for receiving a counter-current. A winding direction of the counter-winding is opposite to a winding direction of at least one of the primary winding and the secondary winding.