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 discloses an improved criterion for differential protection of a T-shaped line. The improved criterion specifically comprises the following steps of: adopting double-end line R-L single-phase out-of-region and in-region fault component models; combining the different fault characteristics of the longitudinal impedance in out-of-region and in-region faults of the double-end line to obtain a protection improved criterion of the double-end line on the R-L single-phase line; according to the similarity, obtaining the protection improved criterion of the T-shaped line on the R-L single-phase line during the occurrence of out-of-region and in-region faults, the protection improved criterion of the T-shaped line during the occurrence of in-region faults after the decoupling of a three-phase line, and the protection improved criterion of the T-shaped line during the occurrence of out-of-region faults after the decoupling of the three-phase line. According to the invention, the improved criterion for differential protection of the T-shaped line solves the following problems in the prior art: the traditional current differential protection is difficult to set and is easily subjected to the influence of the capacitive current and the transient saturation of a current transformer.

The invention relates to a concomitant impedance protection method for a half-wavelength transmission line. The method comprises the following steps of obtaining three-phase currents and three-phase voltages of the location of a relay protection device at an M side of the half-wavelength transmission line and the location of a relay protection device at an N side of the half-wavelength transmission line separately; judging whether the starting quantities of the M side and the N side meet the starting conditions or not; determining a fault point F according to a time difference that the starting quantities of the M side and the N side meet the starting conditions; and opening the relay protection action of the half-wavelength transmission line according to a concomitant impedance of the half-wavelength transmission line. The method provided by the invention can position the fault by a time-difference method according to the characteristics of a failure period, construct the concomitant impedance by compensating the voltages and the currents at two sides of the line, and correctly reflect an internal fault and an external fault of a line region. Two-terminal electric information is effectively utilized by the concomitant impedance protection, so that the protection can quickly and reliably act after the internal fault of the line region happens; the protection does not move by mistake after the external fault of the line region happens; and the protection has relatively high sensitivity.

This invention discloses a current phase-failure protection circuit composed of current detection loop, phase failure distinguishing loop, power output loop and power source. Each of three-phase current test loops has a micro current mutual-inductor and the operation amplifier and RC filter afterwards turn the input current to trapezoidal wave and smooth voltage wave-current signal to be sent to distinguish loop. The current signal is "0" for a failure phase and "1" for a current phase. When the phase fails, a comparator compares the partial values of the two signals to send the compared signal to power amplifying loop to output phase-failure protection action signal to cut-off motor input switch.

The invention is applicable to the power system relay protection field and provides an arc short-circuit protection device and control method. The method comprises the following steps: controlling an arc probe to detect a light by utilizing the spectral characteristic, generating an arc signal if the spectral range of the light is in the detection spectral range; controlling an arc detection unit to converting the arc signal to an arc pulse signal; receiving the arc pulse signal transmitted by the arc detection unit, processing, outputting a driving signal to a protection exit circuit and disconnecting all the incoming lines of a bus bar. The arc short-circuit protection device of the embodiment of the invention utilizes the spectral characteristic to detect the light and has the advantage that the protection can not be operated incorrectly under the action of interference light.

The invention discloses a fast electric arc light protection method. A protection system consists of a singlechip, an arc light sensor, a current transformer and an exit relay. A switch cabinet arc light signal acquired by the arc light sensor is subjected to photoelectric conversion and amplification and sent to the singlechip; a switch cabinet current signal acquired by the current transformer is subjected to conversion and amplification and also sent to the singlechip; when working, the singlechip samples the input light signal and current signal according to set sampling frequency, calculates a relative mutation value of the light and a current light value after each sampling, estimates an effective current value of the next sampling moment according to the current increment and compares the relative mutation value, the current light value and the effective current value with respective set values; and if the relative mutation value, the current light value and the effective current value are all greater than the set values, the singlechip outputs a protection signal and cuts off the power supply of a switch cabinet through the exit relay. The method can eliminate interferenceof the current environment, namely false operation even under significantly bright conditions can be avoided; and impending arc light fault can be prejudged, so the response speed to the arc light fault is increased.

The invention provides a totally-enclosed controllable transformer neutral point protection discharge gap, and the gap comprises a shell; the shell is filled with insulating gas, and a first wall bushing and a second wall bushing are respectively arranged at two ends of the shell in a penetrating manner; the first discharge gap piece and the second discharge gap piece are respectively fixed at theend parts of the extending ends of the first wall bushing and the second wall bushing, and a discharge gap is formed between the first discharge gap piece and the second discharge gap piece; the plasma jet generation device is arranged at an air outlet of the fan and is used for generating plasma jet. According to the invention, the plasma jet flow is formed between the discharge gaps, the transformer is subjected to overvoltage, and when high voltage occurs at the two ends of the discharge gaps, the discharge gaps are immediately conducted; the two discharge gap pieces are arranged in the sealed shell structure, breakdown of the discharge gap is not affected by external environmental factors, dispersity of breakdown voltage of the discharge gap is eliminated, and misoperation of the discharge gap under overvoltage and damage to a transformer are avoided.

The invention discloses a distribution network differential protection method based on a dynamic time bending distance and a floating threshold. The method comprises the following steps: step 1, current sampling devices at two ends of a protected line in a distribution line carry out current signal sampling at a fixed frequency; step 2, when a current fault detection device detects that the distribution line has a break variable current fault, forming current sampling sequences i1 and i2 by current signals within A milliseconds before a fault moment and B milliseconds after the fault, wherein the current signals are collected by current sampling devices at two ends of a protected line; 3, negation is carried out on the normalized current sequence, and then DTW distance and differential protection floating threshold braking threshold value calculation is carried out on the negated current sequence and the normalized current sequence; and 4, calculating whether the DTW distance and the braking threshold value of the differential protection floating threshold meet the criterion or not. According to the method, the good tolerance of the dynamic time warping algorithm to the time domain is utilized, the floating threshold is added to prevent protection misoperation, and the protection reliability is improved.

The invention relates to a transformer no-load switching inrush current and overvoltage eliminating device, which belongs to the field of electrical equipment and electrical engineering, can be applied to air-drop transformer at a power plant or transformer substation, and shows the important role played by the device in safe and stable operation of a power grid in the case of an ultrahigh-voltagepower grid in particular. The transformer no-load switching inrush current and overvoltage eliminating device enables equipment such as a power transformer to be free from mechanical and electrical impact, can improve the service life and also greatly improves the life of a main switch at the same time.

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.