31 results about "Phase ordering" patented technology

The invention discloses a method for detecting lack of a null line in a three-phase power supply, and includes the steps of: obtaining time differences among A phase current, B phase current and C phase current of the three-phase power supply, and recording as Tab, Tbc and Tca; when a phase sequence of the three-phase power supply is judged to be normal according to Tab, Tbc and Tca, controlling a load corresponding to any one of the A phase current, B phase current and C phase current to be turned on, obtaining time differences among the A phase current, B phase current and C phase current again, and recording as Tab', Tbc' and Tca'; and judging whether the three-phase power supply lacks a null line according to Tab, Tbc, Tca and Tab', Tbc' and Tca'. The method for detecting lack of the null line in the three-phase power supply can detect whether the three-phase power supply lacks the null line without additionally adding a related hardware circuit, thereby ensuring power utilization safety without increasing cost. The invention also discloses a device for detecting lack of the null line in the three-phase power supply.

The method for drawing the main busbar connection diagram between the dry-type distribution transformer and the low-voltage switchgear of the present invention relates to the conductive connection of the transformer. The drawing method determines the coordinate values ​​of the relevant parameters in the established XY coordinate system; the drawing method is written in the Visual C++ language. In the human-computer interaction interface, the data required for drawing is input into the computer. Determine the position and shape of each connected copper bar according to the input outlet method, the phase sequence of the input copper bar of the low-voltage switchgear and the coordinate value of each phase of the input copper bar of the low-voltage switchgear, and draw each connected copper bar. According to the coordinate values ​​of the low-voltage side copper bars of each phase of the dry-type distribution transformer, determine the position and shape of each phase outgoing copper bar of the dry-type distribution transformer, and draw the outgoing copper bars of each phase of the dry-type distribution transformer. The drawing method of the invention can significantly shorten the design cycle of the main busbar connection diagram between the dry-type distribution transformer and the low-voltage switchgear, improve the quality of the drawings, and meet the design requirements.

A phase angle acquisition method and system. The method comprises the following steps: collecting a first-phase input voltage and a second-phase input voltage in a three-phase input voltage of a three-phase controllable rectification system; according to the first-phase input voltage and the second-phase input voltage respectively collected at two successive sampling moments, recognizing a phase sequence of the three-phase input voltage; when the phase sequence of the three-phase input voltage is a positive phase sequence, according to a first correlation between a voltage vector phase angle and the three-phase input voltage, acquiring a voltage vector phase angle θ(k) ＝ θ0 + ω*ΔT; and when the phase sequence of the three-phase input voltage is a negative phase sequence, according to a second correlation between the voltage vector phase angle and the three-phase voltage, acquiring a voltage vector phase angle θ(k) ＝ -θ0 - ω*ΔT. A voltage vector phase angle acquired thereby can be directly applied to a system control program, there is no need to perform fault-phase protection, and there is no requirement for the wiring of an input power voltage. The present invention effectively solves the problem that an existing phase angle acquisition method has relatively low intelligence, is inconvenient to apply and has low error-tolerant rate.

Disclosed is a method for connecting one-tower multiple-loop electric transmission lines and buses. The method includes that a simulation model of prestored one-tower multiple-loop electric transmission lines is obtained, and each of the one-tower multiple-loop electric transmission lines in the simulation model is respectively connected with a phase A, a phase B and a phase C of the buses through three circuit breakers; prestored phase sequence arrangement modes of the one-tower multiple-loop electric transmission lines are traversed to obtain a set of phase sequence arrangement modes; each circuit breaker is controlled according to the phase sequence arrangement modes, each of the one-tower multiple-loop electric transmission lines accesses to corresponding phases of each of the buses in the simulation model, and three-phase current imbalance indicators under steady state in the simulation model are calculated and stored; after the prestored phase sequence arrangement modes are traversed, a phase sequence arrangement mode corresponding to a minimum three-phase current imbalance indicator among the three-phase current imbalance indicators is determined; and connection between each of the one-tower multiple-loop electric transmission lines and the corresponding phases of each of the buses according to the determined phase sequence arrangement modes. The invention further provides a corresponding system for connecting the one-tower multiple-loop electric transmission lines and the buses. By the arrangement, efficiency of operation process for connecting the lines and the buses is improved.

The invention provides an electromagnetic induction power transmission system, which comprises a power base station and a ground cable laying system electrically connected with the power base station, wherein the power base station is used for converting a power supply of the power base station into N-phase high-frequency AC and outputting the N-phase high-frequency AC to the ground cable laying system, wherein N is greater than or equal to 2; the ground cable laying system comprises M cable loops which are surrounded by cables; the cable loops of different power supply phases are equal in quantity and N cable loops of the different power supply phases form one cable loop group; N cable loops in each cable loop group are laid according to a default phase ordering rule; and all cable loop groups are laid according to a preset laying rule, wherein M is integer multiples of N. According to the electromagnetic induction power transmission system provided by the invention, leakage flux and a calorific value of the overall system can be reduced and the energy utilization rate is improved.

The invention discloses a phase sequence identification method for three-phase photovoltaic inverters, which includes the following steps of a, setting Usa, Usb and Usc as three phases of sampled voltage, initializing USa as the phase A, sampling voltage values of Usb and Usc when the raising edge of the Usa passes through the zero point, sampling once at each set time, and continuously sampling set times; b, adding one to the positive count value Pos_count with the initial value equal to zero if the sampled value of the Usb is smaller than zero and the sampled value of the Usc is larger than zero, and adding one to the negative count value Neg_count with the initial value equal to zero if the sampled value of the Usb is smaller than zero and the sampled value of the Usc is larger than zero during set times sampling; c, after set times sampling, setting the phase sequence of the Usa, the Usb and the Usc to be A, B and C correspondingly if the positive count value Pos_count is equal to the value of the set times, and setting the phase sequence of the Usa, the Usb and the Usc to be A,C and B correspondingly if the negative count value Neg_count is equal to the value of the set times.

The invention discloses a current phase sequence detection and phase locking device for a three-phase inverter and a phase locking and phase sequence identifying method. The device comprises a waveform amplitude limiting and shaping circuit which is used for waveform amplitude limiting and shaping of an input alternating current, a digital signal processor (DSP) control chip which is used for phase sequence detection and phase locking, and a level conversion circuit which is connected between the waveform amplitude limiting and shaping circuit and the DSP control chip. The method comprises the following steps of: determining the frequency of a power grid, and identifying phase sequence and phase locking. Based on the original inverter, the device and the method realize the automatic detection of phase sequence and phase locking by using the waveform amplitude limiting and shaping circuit and the level conversion circuit, and solve the problem of operation failure of the inverter caused by phase sequence error and output current waveform distortion of an inverter system caused by complete software phase lock.