43results about How to "Strong anti-transition resistance" patented technology

The invention discloses a method for detecting a fault of a power transmission line based on a random matrix, and the method comprises the steps: respectively obtaining three-phase currents of n sample values at two ends of the line, calculating and obtaining a sequences of positive sequence current fault components, negative sequence components and zero sequence components; respectively performing copying and translation processing of each sequence, and carrying out the expansion to form a matrix of each sequence, and then performing the superimposition of a noise matrix to form an original random matrix of each sequence; employing the random matrix theory for transforming the original random matrixes into a standard matrix product; calculating a complex eigenvalue of the standard matrixproduct, calculating and obtaining the average spectral radius of the current component sequence of the line according to the eigenvalue; constructing two criteria for fault detection of the power transmission line, determining a threshold value, and determining that the line whose average spectral radius is less than the threshold value as a faulty line. The method can accurately detect the faulty line, is not affected by the position of the fault point, the fault type, a system operation mode, power flow shift and the system oscillation, can identify a high-resistance ground fault, and has better resistance to abnormal data.

The invention relates to a current differential protection method based on fault component current amplitudes and phase differences. The current differential protection method is characterized in that: a differential protection criterion is formed by the adoption of the current fault component amplitudes at two sides of a protected line and the phase differences at the two sides of the protected line, wherein the differential current value (Icd) is equal to the sum of the current fault component amplitude (the absolute value of [delta]IM) at one side and the product of the current fault component amplitude (the absolute value of [delta]IN) at the opposite side and a cosine function of the phase difference ([phi]) between the absolute value of [delta]IM and the absolute value of [delta]IN, i.e. Icd= (the absolute value of [delta]IM)+(the absolute value of [delta]IN)cos[phi]; and the braking current (Ir) is equal to the difference between the absolute value of [delta]IM and the product of the absolute value of [delta]IN and the cos[phi], i.e. Ir= (the absolute value of [delta]IM)-(the absolute value of [delta]IN)cos[phi], and the differential protection criterion is the following inequation: Icd-KIr>= Idz, wherein K is a braking coefficient and Idz is an action current threshold. If the differential protection criterion is satisfied, an internal fault is determined and the differential protection acts; if the differential protection criterion is not satisfied, an external fault is determined and the differential protection does not act. The current differential protection method related to the invention has the advantages of higher sensitivity for internal faults, higher safety for external faults, fewer effects subjected from the factors, such as the transition resistance, the distributed capacitance, the TA saturation and the like, and good performances.

The invention belongs to the technical field of relay protection of a power system and particularly relates to a single-phase grounding distance protection system and method on the basis of voltage phase comparison. The system comprises a data reading module, a protection calculating module and a protection action module which are sequentially connected. The method comprises the following steps: firstly, calculating and measuring an included angle between a current and a fault voltage by using a relationship of a negative-sequence current phase at the protection mounting position and a negative-sequence current phase at a fault point; respectively calculating phase angles of a fault point voltage and a compensating voltage by using the measured voltage as a reference value; finally, according to the phase difference of the fault point voltage and the compensating voltage when an in-area or out-area fault occurs so as to construct a distance protection criterion. The single-phase grounding distance protection system has excellent resistance to transition resistance; the in-area and out-area faults can be correctly judged regardless of the transition resistance; meanwhile, protection action time and a fixed-value error meet the technical requirements of the grounding distance protection, the calculated amount is small and the single-phase grounding distance protection system has a higher practical engineering value.

The invention discloses a fault location method based on traveling wave difference current. The method comprises steps: one-mode voltage uJ1 and one-mode current iJ1 of a DC line starting end J and one-mode voltage uK1 and one-mode current iK1 of a DC line tail end K are acquired; 1-mode wave impedance Zc1 and 1-mode propagation delay tau1 are acquired; one-mode forward traveling wave difference current di<1><+>(t) and one-mode backward traveling wave difference current di<1><->(t) are obtained; forward or backward traveling wave difference current in the one-mode forward traveling wave difference current di<1><+>(t) and the one-mode backward traveling wave difference current di<1><->(t) is used as a reference standard, the traveling wave difference current in the other direction is translated, and the time difference deltat when a Pearson correlation coefficients are maximum of the one-mode forward traveling wave difference current di<1><+>(t) and the one-mode backward traveling wavedifference current di<1><->(t) is acquired, wherein deltat belongs to a range of -tau1 to tau1, the -tau1 is the propagation delay when the fault happens at the starting end J, and the tau1 is the propagation delay when the fault happens at the tail end K; and a fault location is calculated according to the time difference deltat. Thus, the fault location can be reliably judged, which is not influenced by a fault type, and the anti-transition resistance ability is strong.

This invention relates to high voltage output circuit fault distance protection technique and to one self-adapting earth resistance relay, which forms the relay by fault protection fixing place negative voltage Um2 as electrode volume. This invention relay not only has strong transition resistance force and also with negative sequence volume protection integrated with good self-adapting relay.

The invention relates to the power system relay protection field, in particular to a phase relevant current differential protection method. In order to improve the motion sensitivity of differential protection at the time of internal failure and the brake reliability at the time of external failure to the most extent, the invention adopts the technical scheme. A phase relevant current differential protection method adopts the circuital phase relevant current differential protection criterion: Im+KIn cos Phi>Idz. In the formula, Im and In respectively represent current phasor collected and calculated to be obtained at two sides in the current differential protection and Phi is an angle between Im<&> and In<&>. When the angle of Im<&> is larger than the angle of Im<&>, it is positive. The positive direction of Im<&> and In<&> is from busbar flow to a component to be protected. K is brake coefficient. Idz is the fixed threshold of the current differential protection. The invention is mainly applied to the power system relay protection.

The invention discloses a line fault region identification method. The line fault region identification method comprises the following steps of calculating equivalent impedance Zeq of a T region; calculating current T region transfer functions on the non-fault side and the fault side of the T region when a line suffers from a fault, then obtaining an amplitude-frequency characteristic curve, and thereby determining the number J of layers of wavelet transform corresponding to a reduced frequency band; giving an initial value to a fault region judgment start setting value delta set1, wherein themaximum value of T region fault standard energy difference is delta EJset; measuring and working out line mode currents IL and IR; judging whether the fault region judgment protection needs action ornot; measuring and working out T region standard energy difference delta EJ; and by judging the relation between the standard energy difference delta EJ and the maximum value delta EJset, and then judging a fault region. According to the method, the difference of the fault transient state current energy on the two sides of the T region are extracted through wavelet transform according to the cutting-down effect to the low-frequency component in the fault transient state current energy by the T region, and quick and reliable identification of a fault position can be realized, so that fault region judgment is further realized by integrating fault direction position of each T region.

The invention discloses a distance protection method and system. The distance protection method includes the steps that A, the voltage Um at the distance protection installation position, the current Im at the distance protection installation position, the negative-sequence current Im2 at the distance protection installation position, a distance protection setting impedance boundary value ZMN and the impedance angle thetaline of a circuit where distance protection is located are collected; B, the measurement impedance Zm and self-adaptation distance protection setting impedance at the distance protection installation position are determined according to the collected signals in the step A; C, whether a trip signal or a blocking signal is sent is determined according to the measurement impedance Zm and self-adaptation distance protection setting impedance at the distance protection installation position. Through the distance protection method and system, influence of a transition resistor on distance protection can be eliminated, and correct actions of distance protection can be realized.

The invention discloses a method for judging a fault section of a multi-terminal DC transmission system based on polar wave energy. The method comprises the steps of: recording a fault start moment, acquiring electrical quantities in time segments before and after the fault start moment, and calculating aerial mode components of a voltage and a current at a protection installation part by utilizing the electrical quantities; calculating a polar wave value of each sampling point at a designated moment at the protection installation part in the time segments according to the aerial mode components of the voltage and the current; extracting a polar wave wavelet coefficient of each sampling point at an arbitrary layer in the time segments, and calculating polar wave wavelet coefficient energy;acquiring the maximum value of the polar wave wavelet coefficient energy at the protection installation part in the time segments, regarding the maximum value of the polar wave wavelet coefficient energy as a reference sampling point, taking at least one sampling point after the reference sampling point, and calculating a sum of the polar wave wavelet coefficient energy of the reference samplingpoint and the at least one sampling point; and judging the sum of the polar wave wavelet coefficient energy, and determining the fault section as an intra-cell fault if the sum of the polar wave wavelet coefficient energy is greater than a setting value set in advance.

The invention discloses a single-phase earth fault relay protection method based on a before-fault voltage actual-measurement line. The method comprises the steps of firstly measuring fault phase voltage break variable, fault phase current break variable and zero sequence current at a protection mounting part of a power transmission line and two other normal phase voltages; calculating fault phase voltage before a line single-phase earth fault in real time by using the two normal phase voltage after the line single-phase earth fault; then judging whether the amplitude of the fault phase voltage during the normal operation of the power transmission line is greater than the amplitude of fault phase voltage at a protection setting range of the power transmission line or not, so as to determine whether to send an action trip signal or not. According to the method, memorizing the voltage before the line fault is not needed, and a voltage keeping loop before the line fault does not need to be arranged for relay protection hardware; an action characteristic circle corresponding to the method passes a third quadrant, and an origin of coordinates is in the action characteristic circle, so no protection dead zone for action characteristics exists when an exit single-phase earth fault is protected, and misoperation is avoided when a reverse-direction exit single-phase earth fault is protected.

This invention relates to an earth faulty distance protection technology of high voltage transmission line, which is an adaptive earth direction impedance relay taking the residual voltage Uo at the faulty protection installation place as the polarized volume, which not only has the strong ability of bearing the transient impedance, but also has the advantage of protecting residual component.

The invention discloses a method for protecting a circuit interphase fault voltage phase based on a fault overall-process transient characteristic. Whether a protection device transmits an action skip signal or not is determined according to whether the phase angle by which the fault inter-phase voltage before a circuit interphase short circuit fault occurs is ahead of the fault inter-phase voltage at a power transmission circuit protection setting range falls in the action characteristic zone (90 degrees and 270 degrees). The voltage before the circuit fault does not need to be memorized and a relay is used for protecting hardware without needing to set a voltage maintaining circuit before the circuit fault. An action characteristic circle corresponding to the method for protecting the circuit interphase fault voltage passes the third quadrant and the origin of coordinates is in the action characteristic circle. Thus, an action characteristic of the method is free of protection dead zones when an outlet interphase short circuit fault is protected and misoperation is avoided when a backward outlet interphase short circuit fault occurs. According to the method for protecting the circuit interphase fault voltage based on the fault overall-process transient characteristic, the action characteristic is the transient action characteristic in the whole circuit interphase short circuit fault process and the strong capacities of resisting influences of transition resistance and loaded currents are achieved.

The invention discloses a ground distance relay action method and device and a ground distance relay reflecting a single-phase ground short circuit. The method comprises the following steps that the action criterion comparative quantity is obtained; theta1, theta2 and theta3 are calculated respectively; whether the conditions that the theta1 is larger than 270 degrees and smaller than 360 degrees, the theta2 is larger than 270 degrees and smaller than 360 degrees and the theta3 is larger than 270 degrees and smaller than 360 degrees are satisfied or not is judged respectively; when the theta1 is larger than 270 degrees and smaller than 360 degrees, the theta2 is larger than 270 degrees and smaller than 360 degrees and the theta3 is larger than 270 degrees and smaller than 360 degrees, a signal for making ground distance relay acted is generated. According to the ground distance relay action method and device and the ground distance relay reflecting the single-phase ground short circuit, a phase comparison criterion is simple, the reliability is high, the ground distance relay has strong transition resistance resistant capacity, and a fault phase can be automatically judged.

The invention relates to a hybrid direct current transmission line single-end fault distance measurement method and system, and belongs to the technical field of power system relay protection control. The method comprises the following steps: collecting a line single-end traveling wave coupling box current signal to obtain a ranging signal; calculating the frequency spectrum of a single-end ranging signal, judging whether a frequency difference stable value exists or not, if not, automatically adjusting the length of a data time window, returning to recalculate the single-end frequency spectrum, and if yes, performing fault ranging by using the frequency difference and changing the length of the time window for at least three times to obtain at most two ranging estimation results kn% which exist stably, n = 1, 2; calculating a single-end verification signal, and respectively calculating the deviation delta n% between the distance measurement estimation result and the verification signal, n = 1, 2; the deviation delta n% is compared with a verification threshold value, whether delta n% is smaller than or equal to a preset verification threshold value or not is judged, if yes, the distance measurement result is kn%, and if not, the distance measurement result is 1-kn%. The method is suitable for various complex working conditions of the hybrid direct current system, the distance measurement result is high in accuracy, high in reliability and high in robustness.