41results about How to "Won't move by mistake" patented technology

The invention relates to an alternating current system multi-frequency oscillation composite out-of-step separation criterion method based on wide area measurement information. The method is characterized in that the method comprises the steps that: a phasor measurement unit is utilized to measure voltages, phase angles and frequencies of buses at two sides of a separation section of the circuit, and the voltages, phase angles and frequencies a circuit are used as original data; a calculation center calculates a phase angle difference of the voltages of the buses at two sides of the circuit, and whether [delta][theta] is larger than 130 degrees is used as a starting criterion; the system out-of-step separation criterion is actuated; whether two coherent generator groups cross zero is calculated; a circuit set L is determined through a path searching algorithm; the phasor measurement unit is utilized to collect voltage frequencies at two sides of each circuit in the circuit set L at the zero-crossing moment; whether the derivative d[omega] / dt of bus frequencies at two sides of the circuit to time is smaller than zero is calculated; and the calculation center sends a separation instruction to control the separation of a separation device at an optimal section. The alternating current system multi-frequency oscillation composite out-of-step separation criterion method is scientific and reasonable, high in application, high in reliability and good in effect.

The invention relates to a transformer substation-dispatching center two-stage distribution type restoration control method and belongs to the field of dispatching automation technology in an electric power system. In the method, a control model for spare power source automatic switching of an electric network source is respectively established in a transformer substation and an electric network dispatching center; switch actions in the models are simulated in the dispatching center by a certain cycle and an alarm is given to a spare power source automatic switch which is subjected to overload at a standby power supply side; by judging a monitoring signal between a total automation system and an energy management system, the transformer substation determines different control modes; if the communication is interrupted or reliable, the model of local control is adopted; and if the communication is reliable, the model of transformer substation-dispatching center two-stage control is adopted. By the method, no device needs to be installed in the transformer station and maintained, thereby greatly lowering the investment cost, ensuring the correction of the action of spare power source automatic switching and improving the overall safety operation level of the electric network source.

The invention relates to a method for enabling distance protection to enter power system oscillation interlocking logic. The method includes the following steps: 1) judging whether inter-phase current variation components act; 2) removing distance protection interlocking on yes judgment and calculating each inter-phase impedance Z phi phi on no judgment; 3) comparing the phase impedances with a distance protection II section impedance setting value, enabling a distance protection II section to enter the power supply oscillation interlocking logic and comparing the inter-phase impedances with a distance protection I section impedance setting value when the inter-phase impedances are smaller than the II section impedance setting value, and enabling the distance protection I section to enter the power system oscillation interlocking logic when the inter-phase impedances are smaller than the I section impedance setting value. The method has the advantage of being easy to achieve.

The invention discloses a rapid bus protection method based on a fault component mean value product. The rapid bus protection method particularly includes the steps of (1) collecting the voltages and the currents at the positions, where bus protection elements are located, of outgoing lines connected with a bus in real time; (2) conducting phase-mode transformation on the voltages and the currents of fault components, and extracting respective line mode components; (3) calculating the product of mean values of the line mode voltages and the line mode currents, wherein the plus or the minus of the product of the mean values serves as a basis for judging forward faults and backward faults, a judging result of the fault directions of all outgoing lines serves as a basis for judging whether the bus breaks down or not. According to the rapid bus protection method, the phase-mode transformation is adopted, a bus protection criteria is constructed through the characteristic of the product of the mean values of the line mode voltages of the fault components and the line mode currents of the fault components, and the rapid bus protection method has the advantages of being easy and convenient to use, high in sensitivity, high in motion speed and accurate in recognition, and enabling engineering to be easily realized.

The invention provides a travelling wave protection method and a lightning stroke interference determining method and device of a flexible DC system. Voltage signal of the flexible DC transmission system are collected, and S transformation is carried out on the voltage signals to obtain a 2D multi-time-frequency matrix; and amplitudes of sampling points in the set frequency band are extracted fromthe 2D multi-time-frequency matrix, the change trend of the amplitudes of the sampling points in the set frequency band is determined, if the amplitude change trend satisfies a set condition, it is determined that a lightning stroke interference occurs in a line of the flexible DC transmission system, and otherwise, it is determined that a fault occurs in the flexible DC transmission system, anda travelling wave protection motion is made. According to the methods and device, the computational complexity is low, less time is consumed, a computing process is simple, the travelling wave fault determining efficiency of the DC transmission system is improved, faults can be removed rapidly, equipment damage caused by fault of the power line can be reduced greatly, impact on the AC grid is reduced, power failure loss of the power grid is reduced, severe power failure accidents due to instability of the primary power grid can be prevented, and the reliability of the DC power grid is improved.

The invention discloses a method and device for judging the inter-phase fault of the excitation winding of an AC excitation synchronous motor. A protection device measures the excitation winding current and the stator side voltage and current of the AC excitation synchronous motor; the harmonic components of the maximum phase current of the excitation winding side and the voltage and current of the stator side are calculated respectively in the frequency range from (fs-2fr.max) to (fs+2fr.max) where the fs frequency is filtered out, wherein the fs is the winding current frequency of the statorside, the fr. Max is the maximum excitation frequency of the excitation winding; and protection is performed with the maximum phase current on the excitation winding side as the main criterion and the harmonic components of the voltage and current of the stator side as an auxiliary criterion. When the maximum phase current of the excitation winding side is greater than the current setting threshold and the harmonic component of the stator side voltage is greater than the voltage floating threshold or the harmonic component of the stator side current is greater than the current floating threshold, the protection of alarming or tripping is performed by the delay t. The method and device can solve the situation that the traditional excitation winding over-current protection in variable speedpumping units is easy to be mis-operated when the stator side fails.

The invention discloses an enhanced-robustness differential protection system for a transmission line. The differential protection system comprises an acquisition module for collecting an electrical quantity and sending the electrical quantity to a single-ended quantity protection module, the single-ended quantity protection module for performing single-ended quantity protection operation according to the electric quantity data collected by the acquisition module, a differential adjustment module for adjusting a differential threshold and a braking coefficient according to a calculation result of the single-ended quantity protection module, a differential protection module for latching a differential relay or performing differential protection operation according to the calculation result of the single-ended quantity protection module. With the protection system disclosed by the invention, when a CT line breaking phenomenon occurs at a certain side of a line and an external fault occurs, misoperation of differential protection can be avoided. Besides, while the reliability of differential protection is guaranteed, the anti-transition resistance capability of the differential protection is improved. In addition, the invention also discloses an enhanced-robustness differential protection method for transmission line.