694 results about "Branch current" patented technology

An electrical hand tool machine (1) having a motor switch (2) configured as a button and a current regulator (4) disposed in the current circuit of an electrical motor (3), having a soft-start input (5), in whose branch current a timing capacitor (6) is arranged. A current-direction-dependent element (7) is arranged between the soft-start input (5) and the capacitor (6).

A tool for configuring a branch current monitor facilitates mapping the connections of branch circuits to voltage sources in a power distribution panel.

Provided is a power distribution network intelligent soft switch operation optimization method with simultaneous consideration of switch motion. According to a power distribution system, connection relation of circuit parameters, load level and network topology, system operation voltage level and branch current restriction, distributed power supply connection position, type, capacity and parameters, intelligent soft switch connection position, capacity and parameters, load and distributed power supply operation characteristic prediction curves in an operation optimization cycle, a system reference voltage and a reference power initial value are input; a sequential optimization model of cooperation operation of a power distribution network connection switch and an intelligent soft switch is established; conic model conversion of an object function and non-linear constraints in the sequential optimization model of cooperation operation of the power distribution network connection switch and the intelligent soft switch is carried out according to a conic optimization standard form; linearization of the object function is carried out, the non-linear constraints are converted into linear constraints, second order cone constraints or rotary cone constraints, and solving of the obtained mathematic model is carried out through a CPLEX solver. The provided method avoids tedious iteration and a lot of tests.

The invention discloses a system and method for grid fault identification based on a random point distribution PMU and belongs to the technical field of power system fault identification. The system comprises a fault relative domain identification module, a fault locating module, a fault component identification module and a domain backup protection module. A grid structure changing characteristic is evolved to a branch current difference by the fault relative domain identification module, so that fault relative domain identification is achieved; overall traversal is conducted on a relative domain by the fault locating module, so that accurate location of a fault point is achieved based on a node voltage matching condition; based on virtual current differential, protecting criteria are constructed through an opposite terminal calculated current and a home terminal actually detected current by the fault component identification module, so that fault component identification is achieved; according to domain backup protection operation logic, the near backup tripping function and the far backup tripping function are achieved by the domain backup protection module. Complete domain backup protection under the environment of random PMU point distribution is achieved and the dependence degree on synchronous data of protection is reduced to a great extent.

The invention discloses a parameter identification based photovoltaic array fault diagnosis method. The method includes: identifying relevant parameters of a photovoltaic module according to a parameter identification algorithm; acquiring an output characteristic model of the photovoltaic module under different operating conditions; adopting a fault detection algorithm for fault judgment of a photovoltaic group; acquiring an optimal irradiance So and an optimal module temperature To from data acquired by information acquisition equipment, and inputting into the output characteristic model to obtain an optimal output characteristic equation of the current photovoltaic module, inputting branch current acquired by the information acquisition equipment into the optimal output characteristic equation to obtain an optimal output voltage of a current group, comparing with an actual voltage value of the group, and determining that the group has a hard shadow fault if a difference value exceedsa threshold for consecutive F times; judging a fault type according to a fault judging algorithm; displaying three-section positioning data and operating data of the faulted group on a user interfaceof an upper computer to instruct workers to timely check and maintain the photovoltaic module in fault.

Battery equalization circuits for series charging / discharging and controlling methods thereof are provided. The provided circuit includes a set of series-connected batteries, a switching converter and a magnetic element coupled balance circuit including a magnetic element coupled to the switching converter, wherein the magnetic element takes a branch current from the switching converter to the series-connected batteries so as to cause the set of series-connected batteries to reach a balance.

The invention discloses a current transfer device and method suitable for a hybrid DC breaker. The device comprises a precharging capacitor, a rapid-conduction switch, a primary-side coil and a secondary-side coil; and the precharging capacitor and the primary-side coil form an electric circuit through the rapid-conduction switch, and two ends of the secondary-side coil are taken as leading-out terminals as the device and then are connected to the hybrid DC breaker. When the hybrid DC breaker enables a current to be provided or be cut off, the current transfer device and method provided by the invention can guarantee a branch current of a mechanical switch to be reliably transferred to a branch of a solid DC breaker, and, finally, the current is provided or cut off by the solid DC breaker. Compared with the prior art, the current transfer device and method has the advantages of simple implementation and low cost, and can reduce operation loss of the hybrid DC breaker when normal operation is performed.

The invention discloses an open-circuit fault diagnosis method and system for a staggered flyback type micro inverter. The method comprises the steps that an observer is built to carry out online estimation on the currents of a branch where any master switch device in the staggered flyback type micro inverter is located to generate estimation currents; a current residual is generated according to the estimation currents and actual currents obtained by actually measuring the same position; the norm H2 of the current residual is compared with a residual threshold value, and therefore whether an open-circuit fault happens to the master switch device in the staggered flyback type micro inverter or not is judged. The system comprises the observer, a current residual module and a comparison module, the observer is used for carrying out the online estimation on the branch currents to generate the estimation currents, the current residual module is used for generating the current residual according to the estimation currents and the actual currents, and the comparison module is used for comparing the norm H2 of the current residual and the residual threshold value and judging whether the open-circuit fault happens or not. According to the open-circuit fault diagnosis method and system, the open-circuit fault of the staggered flyback type micro inverter can be found in time, the fault can be processed in time conveniently, and the service life is prolonged.

The invention provides a linear voltage stabilizing circuit. A compensation circuit is added, and the linear voltage stabilizing circuit comprises a first PMOS (P-channel metal oxide semiconductor) tube and a first NMOS (N-channel metal oxide semiconductor) tube. A grate of the first NMOS tube is connected with an output end of the error amplifier, a source of the first NMOS tube is grounded, and a drain of the first NMOS tube is connected with a drain of the first PMOS tube. The drain of the first PMOS tube is connected with the grate of the first PMOS tube and a grate of an adjustment tube. The first PMOS tube and the adjustment tube form a current mirror, and accordingly branch current of the first PMOS tube and the adjustment tube is in direct proportion to load current IL. The first PMOS tube and the first NMOS tube can lead the grate of the adjustment tube to be a low-resistance node, a low-frequency pole at the low-resistance node can be in high frequency, and stability of the whole circuit is compensated. Resistance of the grate of the adjustment tube varies with the load, little current is consumed in light load, and the current is barely consumed in a no-load state. High current conversion efficiency in light load or no load state can be guaranteed.

A method is provided for measuring D-Q impedance of a component of a polyphase power grid connected to a grid node, and evaluating the margin of stability at a node using Nyquist diagrams generated from the measured D-Q impedance data. A generator, coupled to the polyphase power grid, is controlled to induce suppressed-carrier stimulus current into the grid node. Circuitry measures response signals of suppressed-carrier form existing within a bus voltage at the grid node and a branch current of the component being measured. The method includes measuring complex voltage components of the response signals contained in the bus voltage and complex current components of the response signals contained in the branch current to form simultaneous equations that are resolved to determine the D-Q impedance parameters Zqq, Zqd, Zdq and Zdd of the measured component.

The invention discloses a current adaptive protecting method which belongs to the technical field of an electric power system. The current adaptive protecting method comprises the following steps: utilizing a fault network equivalence simplifying method and a fault steady state component theory to obtain a relation between a node voltage and a fault steady state injection current before failure happens; utilizing a network system parameter matrix to construct the linear mapping relation between the fault steady state injection current and a fault steady state branch current; and utilizing a fault steady state current of a related branch to form novel current adaptive protection. According to the invention, the network system parameter matrix is used for eliminating the effect of a distributed power supply on the fault steady state current of each branch, thereby avoiding a protective relaying false operation caused by the accessing of the distributed power supply. A setting algorithm is simpler and more practical. A main protection scope is 72.88%-72.94% of the full length of a circuit. A protection scope of spare protection which extends to a subordinate circuit is less than the protection scope of main protection; therefore the demand of protection matching is met.

The invention provides a loop filter circuit used in a charge pump phase-locked loop. The charge pump phase-locked loop comprises a frequency and phase discriminator, a charge pump, a loop filter, a frequency divider and a voltage-controlled oscillator; the front end of the loop filter is connected with the charge pump and the rear end is connected with the voltage-controlled oscillator; the loop filter circuit comprises a control logic, a front buffer circuit, a time delay switch and a rear filter circuit; when the time delay switch is conducted, the whole loop filter circuit can operate normally; but when the time delay switch is off, the charge pump is conducted with the front buffer circuit and is not conducted with the rear filter circuit; the time delay circuit of the time delay switch refers delays time of the clock, and the on-off of the time delay switch is controlled by the control logic of the loop filter circuit; by adopting the circuit, the problem of stray reference caused by the mismatching of the upper and lower branch currents in the charge pump is solved, and the performance of the loop filter circuit of the charge pump phase-locked loop is improved.

The invention relates to an energy control method of an urban rail super capacitor storage system. The method comprises the following steps that: a direct-current power supply network voltage Udc and a super capacitor module group terminal voltage Usc are collected respectively and an output branch current Isc of the super capacitor module group is connected within each control period; a charging-discharging threshold calculation module outputs a charging threshold value Uchar and a discharging threshold value Udis in real time based on the super capacitor module group terminal voltage Usc within each control period; and according to a relation between the charging threshold value, the discharging threshold value, and the direct-current power supply network voltage Udc, a current control period of an urban rail super capacitor storage system is determined to be in a charging state, discharging state or a standby state. According to the energy control method provided by the invention, multiple sets of urban rail super capacitor storage systems can work in a coordinated mode and thus the urban rail super capacitor storage systems can absorb brake energy of the train fully and effectively, thereby improving the energy utilization efficiency of the urban rail power supply system. Moreover, fluctuation of the direct-current side voltage of the power supply system can be inhibited.

The invention discloses a high-voltage capacitor bank branch current monitoring device, comprising a self-excitation energy obtaining and power converting circuit, a current detection and acquisition circuit, a CPU data acquisition and controlling circuit and a wireless transceiving circuit, the self-excitation energy obtaining and power converting circuit obtains energy from the high-voltage line and converts and outputs direct voltage; and the current detection and acquisition circuit collects current instantaneous value, and outputs to the CPU data acquisition and controlling device, which is used for finishing branch unbalanced current AD alternating current sampling, current harmonic calculation and finishing bidirectional wireless digital transmission via the wireless transceiving circuit. The monitoring device solves the problem of monitoring protection of a capacitor bank under high potential, discloses the damage mechanism of the capacitor bank by taking the branch unbalanced current and harmonic distribution in the fault process of the capacitor bank as the analysis basis, thus reducing fault rate of the capacitor bank and having significant meanings in improving power grid safe operation level and economic efficiency.

The invention relates to a power conversion unit connected in parallel, which comprises N power conversion circuits, N or N-1 voltage adjusting circuits and a control circuit connected in parallel between a power supply and a load, wherein N is more than or equal to 2, each voltage adjusting circuit is arranged at the front end of one power conversion circuit respectively, and the control circuit is applied to detecting output voltage of each power conversion circuit and sending control signals to the voltage adjusting circuits so as to adjust the output voltage of the voltage adjusting circuits, and each power conversion circuit has same output current. The power conversion unit solves the problems that when the resonant parameters of the power conversion circuits have differences, branch current is unbalanced and even certain branches do not transmit power to secondary sides. Besides, the power conversion unit cannot increase the output impedance and reduce the Q values of the power conversion circuits to make the efficiency of the complete machine reduced a lot.

The invention relates to a method for estimating state of a distribution network for supporting large-scale current measurement, and belongs to the automatic dispatching field of power systems. The method comprises the following steps of: squaring a branch head end power and a branch current amplitude to obtain an evaluated variable, and establishing a new state estimation model of an exponentialtarget function according to a power grid model of an actual power grid and real-time measurement data; and estimating the branch head end power and the branch current amplitude by adopting a Lagrangian multiplier method so as to calculate active power and passive power of equipment such as a circuit, a transformer, a generator, a load and the like. The method can directly establish measurement equations for branch current amplitude measurement, branch power measurement, node voltage measurement and injection power measurement, does not need measurement conversion, does not introduce measurement conversion errors, is convenient to implement, and has high calculation efficiency.

A sensor array including multiple current sensors provides input for power measurement and management systems. The sensor array includes split ferrite cylinder portions connected by a frame, so that when the array is installed around multiple branch circuits in a power distribution panel or raceway, the ferrite cylinders are completed to surround the conductor(s) of the associated branch circuit. Voltage sensing may also be incorporated within the sensors by providing an electrically conductive plate, wire or other element that capacitively couples to the corresponding wire(s).

The invention discloses a buffer based on a source electrode follower and belongs to the technical field of analog integrated circuit design. The buffer comprises a pseudo differential input level, a cross coupling common source level, a current source and a capacitance load, wherein the pseudo differential input level is used for receiving a difference input signal; the cross coupling common source level is connected with the pseudo differential input level, used for forming negative resistance and offsetting output resistance of the buffer; the current source is connected with the pseudo differential input level and used for providing branch current of the buffer; and the capacitance load is connected with the pseudo differential input level and used as output load of the buffer. The negative resistance is formed by the cross coupling common source level, so that the buffer offsets the output resistance of the high-speed buffer and realizes unity-gain buffering output. The buffer based on the source electrode follower realizes ultra-high speed, the unity-gain buffering output and high dynamic characteristics by theoretical analysis and simulation verification.

A power monitoring system that reduces the need for transient voltage suppressors while using current transformers on an associated support operating using a current mode.

A power meter for monitoring current in a power cable annunciates an alarm if the current transgresses one or more alarm current limits. False alarms are avoided by delaying the activation of the alarm for a delay interval following determination that current is flowing in the monitored conductor.

The invention relates to a distribution network topology error identification algorithm based on AMI measurement information, which is characterized by comprising the following steps: S1, calculatingthe voltage Upc of a coupling node to which each load belongs, and obtaining a coupling node voltage sample space to which the loads belong; S2, calculating the current I<L> of a branch to which eachload belongs, and obtaining a branch current sample space to which the loads belong; S3, calculating the voltage correlation coefficient and the current correlation coefficient of the loads accordingto the voltage and current sample spaces obtained in S1 and S2; and S4, completing topology calibration and correction. The running time required for identification is reduced. The quick action of topology identification is ensured, and the reliability and effectiveness of topology identification are ensured.

The invention relates to a method for calculating three-phase tide of a power distribution network on the basis of neutral point offset. The method includes steps of acquiring medium-voltage power distribution network topology, numbering various nodes and various branches on a calculation feeder line; introducing neutral point voltage offset of each node; rectifying calculated phase voltage values of all the nodes by the neutral point offset; calculating load current value of the nodes by adopting the rectified calculated phase voltage values; calculating three-phase branch current of each branch and three-phase voltage value of each node by forward-back substitution method; iterating by the Newton-Raphson method, and rectifying the neutral point voltage offset; dissolving the three-phase voltage by means of hybrid iteration; judging whether the three-phase voltage value in the step G meets iteration terminating condition or not; and calculating three-phase tide distribution and outputting result. Restraint relation among three-phase current is processed by introducing the neutral point offset, and the problem about calculation of the three-phase tide of the power distribution network is effectively solved by means of advantages of mixed iteration method combined the forward-back substitution with the Newton-Raphson method.

The invention discloses a method and a device for controlling a parallel interleaving parallel feedback circuit (PFC), wherein the method comprises the following steps: controlling to acquire a voltage loop output quantity by a voltage outer loop, and acquiring a current reference waveform by a voltage loop output quantity and an input voltage of a circuit; depending on the current reference waveform as well as sampled branch currents of n pieces of branches, controlling various branch current loops, respectively acquiring current loop outputs of the various branches, and making the waveforms of the various branch currents follow the current reference waveform; calculating an ideal driving feedforward quantity, depending on the current loop outputs of the various branches as well as the ideal driving feedforward quantity, acquiring a final driving output value; and sending a wave by the driving pulses of the n pieces of branches depending on the final driving output value. According to the technical scheme, the current ripple voltage on the inductor is reduced, and the frequency of the ripple current is doubled, thereby reducing the ripple of the inductor and the heating and improving the efficiency of the device.

The invention provides an MMC-based bipolar flexible direct-current power grid short-circuit and grounding fault current prediction method, which comprises the following steps: in a sub-module capacitor discharge stage before MMC locking, enabling an MMC to be equivalent to an RLC series branch; based on the influence of alternating current feed-in, an MMC adopting a constant active power controlmode is established as an equivalent circuit in which a current source and an RLC series branch are connected in parallel; considering a bipolar short-circuit fault and a monopole grounding fault of the flexible direct-current power grid, and building an equivalent circuit model of the direct-current power grid in a fault state; and based on the direct-current power grid equivalent circuit model,establishing a flexible direct-current power grid state-space equation and solving to obtain branch current and MMC equivalent sub-module capacitor voltage when the direct-current power grid fails. The fault current of the bipolar flexible direct-current power grid based on the MMC under the conditions of the bipolar short-circuit fault and the single-pole grounding fault is predicted, the methodis reliable and high in precision, and the discharge rule of the MMC is disclosed.

The invention relates to a plug-type circuit breaker with few parts, good assembly operational performance, uneasily deformed plug-in terminal and high contact reliability. The plug-type circuit breaker is formed by connecting a plug adaptor and a circuit breaker main body bolts with a bolt connecting terminal. In the plug-type circuit breaker, a plug box is internally installed with: the plug-in terminal connected with any one of multiple bus poles by plugging in; and a socket mechanically connected with the circuit breaker main body. In the plug adaptor, a pair of convex parts is integrally formed on the plug-in terminal. A plug-in terminal mounting part composed of an opening is formed on the socket. At the same time, the plug-in terminal is electrically connected with the circuit breaker main body by a branch current conductor. The opening is actively embedded with the convex parts to support the plug-in terminal so that the plug-in terminal can rotate in a direction orthogonal to the bus poles.

The invention relates to a method for judging a turn-to-turn short circuit fault position and the number of short circuit turns of a steam turbine generator rotor, belonging to the field of master equipment relay protection of a power system. The method is characterized by comprising the following steps of: calculating a fault by utilizing a generator rotor turn-to-turn fault analysis technology based on a multi-loop model, preferentially selecting a detection object, and determining the criterions of the fault type and the fault position of the rotor by utilizing an effective value and a phase angle of a characteristic harmonic component; fitting on the basis of a calculating result to obtain a functional relation between stator branch fault characteristic harmonic current of windings indifferent slots during short-circuit and the number of short circuit turns; and determining the number of the short circuit turns through acquiring the current of a branch of the stator from a generator end, filtering the effective value and the phase angle of the fault characteristic harmonic component of the branch current through fast Fourier analysis, determining the fault position according to the criterions of the fault type and the fault position and solving an equation consisting of the functional relation consisting of the stator branch fault characteristic harmonic current and the number of short circuit turns.

The invention relates to a photovoltaic array fault diagnosis method and device based on spatiotemporal distribution characteristics. A photovoltaic output time component and a spatial component are calculated and obtained by a time and spatial distribution function for the photovoltaic array output starting from the historical operation data and the historical environment data of a photovoltaic power plant, the components are used as a training data set, a probabilistic neural network is trained by the training data set, a photovoltaic array fault diagnosis model is obtained, a time functionand a spatial function for photovoltaic branch output are established to effectively describe the distribution law of string current under different fault conditions, the photovoltaic power station DCside array fault diagnosis method established based on the probabilistic neural network is high in diagnosis precision, and finally, branch current data are inputted to the photovoltaic array fault diagnosis model to realize diagnosis of multiple types of fault, and the existing data of the actual project can be fully utilized effectively.

The invention discloses a method for achieving real-time calculation and high accuracy of large-scale power grid theoretical line loss. The method for achieving real-time calculation and high accuracy of large-scale power grid theoretical line loss can widen the range of network calculation and improve work efficiency and calculation accuracy. The method for achieving real-time calculation and high accuracy of large-scale power grid theoretical line loss comprises the following steps that a clock of a data collection system synchronizes with a GPS clock and then compares the time with the time of a collection device, the collection device compares the time with the time of an ammeter; branch currents, node voltage, active power, reactive power, active electricity quantity and reactive electricity quantity are connected with nodes or branches in a node-branch model; a data collection system module is arranged to obtain a power grind main wiring diagram, parameters of elements and operation parameters from an SCADA, GIS and measurement automation system in real time; the power grind is classified; a data maintenance system module and a theoretical line loss calculation module are arranged to carry out classification calculation on the power grind according to voltage, areas, lines and power distribution chambers; a centralized control center module is arranged; a theoretical line loss analysis module is arranged to finish calculation and analysis on the theoretical line loss of the whole power grid.