968 results about "Earthing system" patented technology

A system and method for changing wind turbine rotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the wind turbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

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

The invention discloses an adaptive transient characteristic fault line detection algorithm for a non-effectively earthed system by utilizing wavelet packet frequency division characteristics. The method comprises the following steps of: (1) monitoring a waveform of a bus zero sequence voltage, and when an instantaneous value of the bus zero sequence voltage exceeds a setting value, starting a fault line detection device and recording, and acquiring transient zero sequence current of each line; (2) calculating the selected frequency band of the system according to the grid structure and line parameters of a power distribution network; (3) decomposing and reconstructing the zero sequence current of the line by employing a wavelet packet, and taking three lines with the highest zero sequence current envelope line area as alternative fault lines; (4) calculating a scaling factor r and a transient factor h, and judging the earthing fault generation type; and (5) calculating a first amplitude value comparison criterion and a second polarity comparison criterion according to the earthing fault type, introducing a third criterion when the two criterion results are inconsistent, and selecting the earthing line. The method is accurate in line selection, and the earth line selection reliability of the power distribution network can be improved.

A method for selecting wire of single phase earthing in neutral point noneffective earthing system includes making instant short circuit between neutral point and ground at position near two ends voltage polarity from positive to negative over zero by short circuiter set between neutral point and ground when single phase earthing is occurred in neutral point noneffective earthing system and state is stabilized in order to generate a short circuit pulse current being used to judge earthing line through short circuit detector. The device for realizing said method is also disclosed.

To provide a magnetizing inrush current suppression device for transformer and control method of same, which accurately calculates the residual magnetic flux when a transformer installed in a non-solidly earthed system, is interrupted by circuit breakers, and which enables suppression of the magnetizing inrush current occurring when three single-phase circuit breakers or single-phase circuit breakers are used for simultaneously supplying power to three phases of the transformer, without providing a circuit breaker with a resistor or other equipment to enlarge the circuit breaker. The device has steady-state magnetic flux calculation means for calculating the line-to-line steady-state magnetic flux of three-phase power supplies, residual magnetic flux calculation means for calculating the primary line-to-line residual magnetic flux of the transformer when the circuit breakers interrupt the transformer, phase detection means for detecting a phase at which the polarity and magnitude of the calculated steady-state magnetic flux and residual magnetic flux coincide for each line-to-line. Closing control means firstly causes only two-phase of the circuit breakers, which are connected with the line-to-line, to close at the detected phase, and then causes the remaining one-phase circuit breaker to close.

A method for achieving single-phase earth fault line selection of a small current grounding system is characterized in that a high-precision zero-sequence current transformer is adopted by each feeder line; a single-phase earth fault of the system is confirmed when the instantaneous value of the zero-sequence current i0 of any one feeder line exceeds a set threshold /I0 /; comparison is conducted on symbols of all loop circuits at the moment of threshold triggering, and data after the triggering do not participate in judgment; the symbol of a faulty line current is unique and opposite to the symbols of non-faulty line currents, and the number of non-faulty lines is larger than or equal to 2; when the symbols of all the currents are identical, a bus earth fault is confirmed. The method for achieving single-phase earth fault line selection of the small current grounding system is adaptable to three grounding modes, namely neutral non-grounding, arc suppression coil grounding and neutral point high resistance grounding, of the small current grounding system and is not affected by a grounding moment phase angle, system unreal grounding and TV disconnection, and correction operation can still be achieved when the zero-sequence voltage of a bus is reduced to be 10% of a phase voltage by a transition resistor.

The invention relates to a resonant earthed system fault line selection method utilizing fuzzy K-means clustering. The resonant earthed system fault line selection method comprises the following steps of 1 performing stretching transformation treatment on transient-state zero-sequence current of each line to improve similarities of transient-state zero-sequence currents of non-fault lines; 2 dividing the transient-state zero-sequence currents of all of lines according to a certain time period, performing subsection phase plane transformation to obtain Euclidean distances from all of phase points of the transient-state zero-sequence current of each section to determinacy points x and y on a phase plane so as to extract local features of the transient-state zero-sequence currents of all of subsections and obtain feature matrixes of global features of all of lines; 3 performing normalization processing on elements in the feature matrixes to improve comparability; 4 utilizing a fuzzy K-means clustering method to perform clustering on the normalized feature matrixes, dividing the transient-state zero-sequence currents of all of lines into two categories and the lines independently included in one category are fault line. The method improves the automation degree and line selection margin.

A power distribution network one-phase grounding fault location method based on a zero sequence voltage belongs to a power distribution network grounding fault location method. The fault location method starts from an overall zero sequence parameter of a single-end radial medium voltage power distribution network, analyzes a one-phase grounding fault while taking a distributed parameter model influence into consideration, measures a steady-state zero sequence voltage value and a zero sequence current of each feeder line at a bus position and at a tail end of each outlet line, and finds zero sequence voltage variation characteristics of a fault feeder line and non-fault feeder line. According to the invention, a large number of existing devices are used, the data sampling requirement is low in terms of being real-time, and the method of the invention is easy to realize; the simulation model analysis is established according to the actual parameters, so that the fault location can be realized in the system in which the neutral point is not grounded or the neutral point is grounded through an arc suppression coil; the precision is quite high; and the location method of the invention can be applied to the medium and low voltage power distribution network.

Methods and apparatus are described to detect, measure, and determine the presence of unknown Groundloop currents flowing through unidentified circuit pathways within the wiring system distributed within a portion of a fuselage of an airplane substantially made from fiber-reinforced composite materials to avoid catastrophic failures of the electrical system within such an airplane.

The invention discloses a fault diagnosis method which is used for determining whether a single-phase earth fault occurs in a low current earth system and determining the position of a fault point. The method comprises the following steps of: (102) synchronously acquiring the power frequency voltage of a busbar of the low current earth system and the current traveling wave of all outgoing lines in real time; (104) determining an outgoing line with turbulence in all the outgoing lines when the turbulence occurs in the low current earth system; (106) determining whether the single-phase earth fault occurred in the low current earth system according to the power frequency voltage; and (108) determining the outgoing line with the turbulence as a faulty outgoing line to obtain the distance between the acquisition point and the fault point on the current traveling wave of the faulty outgoing line when the single-phase earth fault occurred in the low current earth system. The invention discloses a fault diagnosis device. The single-phase earth fault of the low current earth system can be detected according to the fault diagnosis method and device.

An ungrounded or floating DC electrical power distribution system may experience a single line to ground fault. Such a fault may not disrupt operation of the system, but its presence may raise a risk of additional problems if left uncorrected. A system for progressively grounding the ungrounded system may be initiated when a line to ground fault is suspected based on the voltage difference measured to a common chassis point. As grounding through successively lower impedance proceeds, fault current may increase and detection of severity of the line to ground fault may be more readily achieved, thus facilitating localization of the fault. Localization may be achieved through an analysis of direction of capacitive currents in isolatable zones of the system.

The invention discloses a single pole grounding system and a fault detection device and method. According to the single pole grounding system and the fault detection device and method, before the grounding of a normal grounding point, the direct current bus voltages of a system and impedance sampling signals are obtained to calculate the earth impedance of the positive / negative pole of the single pole grounding system, then whether fault grounding points exist is judged, pre-detection before system operation is achieved, and no faults exist before the operation of the system; after the normal grounding points are grounded, whether a grounding fault exists is judged by detecting leaked currents; the grounding pole multipoint grounding fault and non-grounding pole grounding fault which occur during the operation process can be detected when the system is down or the normal grounding points are not grounded through calculating the earth impedance of the positive / negative pole of the single pole grounding system again. Thus, the single pole grounding system and the fault detection device and method achieve the detection on the multipoint grounding fault of the single pole grounding system and the non-grounding pole grounding fault which may occur at the same time.

A method for detecting line fault direction judges the fault direction by calculating instant idle power or specific frequency component idle power of transient state voltage current generated by the fault. The fault direction can be detected out quickly within 5 ms and tripping command is followed immediately to separate the fault line out for protection.

In an X-ray generating device of the neutral grounding system, to remove an unbalance voltage generated due to difference in impedance of parallel transformer coils of the high voltage transformer and particularly an unbalance voltage involved with difference in impedance above and below the neutral points generated in a metal X-ray tube, a plurality of currents flowing in opposite directions through primary windings of the parallel transformer coils in the high voltage transformer are passed through by or wound around a common toroidal coil or wound around an outer circumference of the toroidal coil at a predetermined ratio of winding number, and the unbalance voltage occurring to the secondary side is cancelled by changing primary current with magnetic behavior.

The invention provides a distribution line single-phase grounding traveling wave protection method. The method includes: step 102, respectively acquiring fault zero modal initial current traveling wave within a frequency range of 0-100KHz and fault zero modal initial voltage traveling wave within a frequency range of 0-100KHz, comparing wavefront polarity of the fault zero modal initial current traveling wave with that of the fault zero modal initial voltage traveling wave, and enabling a first criterion to be established when the polarity of the fault zero modal initial current traveling wave and the polarity of the fault zero modal initial voltage traveling wave are opposite; step 104, acquiring three-phase current magnitude and zero-sequence voltage magnitude under the condition that the first criterion is established, and enabling a second criterion to be established if the zero-sequence voltage magnitude is larger than a first setting value and the three-phase current magnitude is smaller than a second setting value; and step 106, judging to determine that a single-phase grounding fault occurs and giving out a trip signal or an alarm signal when the first criterion and the second criterion are both established. By the technical scheme, when the single-phase grounding fault occurs in a distribution line neutral point ineffective grounding system, the fault can be detected quickly and accurately, and reliable protection actions can be taken.

The invention relates to an identification method of ground fault phases in a three-phase ungrounded system and an identification device thereof. The identification method comprises the following steps: firstly selecting any line voltage in the three-phase ungrounded system as reference voltage, determining value domains of phase difference between theoretical zero-sequence voltage of the fault phases and the reference voltage when a ground fault occurs on each phase aiming at the reference voltage, and carrying out real-time online acquisition of the actually measured zero-sequence voltage; if the actually measured zero-sequence voltage is zero, judging no ground fault occurs; and if the actually measured zero-sequence voltage is not zero, calculating the phase difference between the actually measured zero-sequence voltage and the reference voltage, and judging which value domain the phase difference falls into so as to judge that the ground fault occurs on the phase corresponding to the value domain. The identification method can rapidly judge the ground fault occurs on A phase or B phase or C phase in the three-phase ungrounded system and directly point out the ground fault phases while finding out the fault, thus reducing troubleshooting time, being beneficial to eliminate faults timely, and guaranteeing safe operation of the system.

The invention provides a small current grounding system single-phase earth fault direction detecting method utilizing the linearity relation between a line zero sequence current and a voltage derivative and belongs to the field of relay protection of power distribution networks. The linearity relation between upstream and downstream voltages and currents of a fault point is analyzed when a single-phase earth fault occurs in an unearthed and arc suppression coil grounded system, a method for fault direction detection by utilizing the linearity relation between the line zero sequence current andthe voltage derivative at a detection point is provided. The zero-sequence voltage and zero-sequence current at each detection point are acquired, linear fitting is conducted on a zero-sequence current sample value sequence and a corresponding zero-sequence voltage difference value sequence, it is judged whether the detection points having the fit goodness greater than a threshold value and the fitting function slope greater than 0 are located at the downstream of fault points or not, if not, the detection points are located at the upstream of the fault points. The method can be simultaneously suitable for low-resistance and high-resistance earth faults of a small current grounding system, improves the adaptability of a fault direction detection algorithm and has a wide actual applicationvalue.

The invention discloses a ground line selection method for a small current grounding system. The method solves the problem that the prior line selection method is low in sensitivity and generates errors in line selection. The method comprises the following steps: 1, single-circuit lines and double-circuit lines are numbered and placed in a microcomputer; 2, the microcomputer judges whether the system is grounded or not and identifies a grounding phrase of the system; 3, according to the number of the single-circuit lines and the double-circuit lines, the microcomputer calculates a grounding transfer characteristic formula with zero sequence current which is measured during the normal operation of the system, zero sequence current of the single-circuit lines, zero sequence voltage of a bus and zero sequence current of the double-circuit lines which are measured when the system is grounded, and zero sequence voltage of a bus, zero sequence current of the double-circuit lines and zero sequence current of the single-circuit lines which are measured during grounding transfer of the system; the result of the calculation is compared with grounding current IJ passing through a split phase switch of the grounding phase during grounding transfer to determine a fault line. The method has the advantages of the characteristics of high sensitivity and accurate line selection and great significance on accurate identification of grounding circuit, grasp of grounding and arc-suppression coil conditions of the system, and promotion and improvement of safe and reliable operation of the system.

Provided is a self-adaptive line selection method for a single-phase earth fault of a resonant earthed system. The self-adaptive line selection method for the single-phase earth fault of the resonant earthed system comprises the steps that when zero-sequence voltage of the system is greater than setting voltage, a fault line selection device is started and records bus zero-sequence voltage and zero-sequence currents of circuits before the fault and after the fault; atomic decomposition improved based on a PSO is carried out on the bus zero-sequence voltage, time of occurrence of the fault is determined, preprocessing is carried out on the collected zero-sequence currents of the circuits based on the time of occurrence of the fault to obtain transient state zero-sequence currents of two power frequency cycles, then the atomic decomposition improved based on the PSO is carried out on the transient state zero-sequence currents, and an optimal matched atom representing a transient state free oscillation component and a decaying direct current component of the transient state zero-sequence current of each circuit is obtained; corresponding characteristic information of the optimal matched atoms is extracted; according to the size of an energy entropy scaling factor, a single-phase earth fault occurrence mode is determined, and self-adaptive fault line selection is carried out according to the mode.