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

The invention discloses a boundary-characteristic-based non-unit protection method for a multi-terminal flexible direct-current power grid system. The method comprises: wavelet decomposition is carried out to extract a high-frequency component in a fault current; a high-frequency transient energy value Ej and a voltage drop VL on a smoothing reactor of the fault current are calculated; a fault direction is determined by using the voltage drop VL on the smoothing reactor; if no fault occurs in a positive direction, exit from a fault protection process is carried out; if a fault occurs in the positive direction, whether a fault occurs in a region is determined by using the high-frequency transient energy Ej criterion; if a condition that the Ej is larger than an Eset value is met, the in-region fault is determined and the fault protection action is executed; and otherwise, no fault in a region is determined and exit from a fault protection process is carried out. Compared with the prior art, rapid fault identification can be realized within a few of milliseconds and the protection action is carried out rapidly. Moreover, fault determination and identification are carried out only by using the electric quantity at the terminal without communication with other convertor stations, so that the costs are lowered. The method has the high anti-transition-resistance capability and the protection applicability is high.

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 belongs to the technical field of electric power system relay protection, and in particular relates to a single-phase grounding distance protection system based on voltage phase comparison and a method thereof. The system includes a sequentially connected data reading module, a protection calculation module and a protection action module; the method includes : First, use the relationship between the negative sequence current phase at the protection installation and the negative sequence current phase at the fault point to calculate the angle between the measured current and the fault voltage; then, use the measured voltage as a reference value to calculate the phase of the fault point voltage and the compensation voltage Finally, according to the phase difference between the fault point voltage and the compensation voltage when the fault is inside and outside the fault, the distance protection criterion is constructed. The invention has a good anti-transition resistance capability, and can correctly distinguish faults inside and outside the zone regardless of the size of the transition resistance; at the same time, the protection action time and fixed value error meet the technical requirements of grounding distance protection, and the calculation amount is small, which has a high engineering practical value.

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 discloses a method for judging a fault section of a multi-terminal direct current transmission system based on polar wave energy: record the fault start time, collect the electric quantity in the time section including before and after the fault start time, and use the electric quantity to calculate the protection The linear mode components of the voltage and current at the installation site; according to the linear mode components of the voltage and current, calculate the extreme wave value of each sampling point in the time segment at the specified moment to protect the installation site; extract each sampling point in the time segment at any time Calculate the energy of the polar wavelet coefficient for the polar wavelet coefficient of the first layer; obtain the maximum energy value of the polar wave wavelet coefficient at the protection installation in the time zone, use the maximum energy value of the polar wave wavelet coefficient as a reference sampling point, and take at least One sampling point, calculate the energy sum of the polar wavelet coefficients of the reference sampling point and at least one sampling point; judge the energy sum of the polar wavelet coefficients, if the energy sum of the polar wavelet coefficients is greater than the preset setting value, then judge the faulty section In-zone failure.

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 discloses a method and system for longitudinal protection of photovoltaic power generation grid-connected tie lines. The method includes: judging whether the sudden change in current of a certain phase in three phases satisfies the first condition or whether the zero-sequence voltage satisfies the second condition; If the sudden change of a certain phase current meets the first condition or the zero-sequence voltage meets the second condition, the longitudinal protection will be started, and the data window of the preset time period will be selected after a delay, and the PV side and the tie line of the tie line will be calculated separately by phase. The sum of the current and the voltage on the system side; the zero-sequence compensation is performed on the sum of the voltages on the photovoltaic side and the system side of the tie-line of each phase to obtain its derivative, and based on the photovoltaic side of the tie-line of each phase and the system side of the tie-line Calculate the correlation coefficient of each phase by the sum of the currents; compare the calculated correlation coefficient with the setting threshold, and execute the corresponding protection action based on the comparison result. Realized that it can act accurately in the case of different fault types at different fault locations.

A DC line unipolar ground fault protection method based on the similarity of the current mode components, based on the similarity between the sum of the zero-mode components and the one-mode components of the current at both ends of the line According to the differences, a protection method for unipolar ground faults of DC lines is proposed, and the data window length can be flexibly selected according to actual needs. The protection method can reliably distinguish unipolar ground faults inside and outside the DC line area, and has a strong ability to resist transition resistance .

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.

A distance protection method and system, the distance protection method comprising: A. Collecting the voltage at the distance protection installation place, the current at the distance protection installation place, the negative sequence current at the distance protection installation place, and the distance protection setting impedance boundary value ZMN and the line where the distance protection is located; Impedance angle B. Determine the measured impedance Zm at the distance protection installation location and the adaptive distance protection setting impedance according to the collected signal in step A; C. Determine whether to Send a trip signal or a blocking signal. By using the distance protection method and system of the present invention, the influence of the transition resistance on the distance protection can be eliminated, and the correct action of the distance protection can be realized.