20 results about "Current transformer saturation" patented technology

The invention discloses a current transformer saturation identification method, system and device and a medium, and the method specifically comprises the steps: continuously collecting the voltage and current data of each phase of secondary side at two sides of a protected line, and determining whether protection is started or not according to a differential current; performing first-order differential processing on the secondary current to obtain differential secondary current, and performing normalization processing on the differential secondary current to obtain normalized secondary current; extracting the phase of the normalized secondary current, and constructing an ideal sine reference waveform with the same phase; respectively calculating the phase trajectory fractal dimensions of the normalized secondary current and the reference waveform; and judging the saturation state of the current transformer according to the fractal dimension deviation, if so, judging that the current transformer is saturated, otherwise, judging that the current transformer is unsaturated. The system comprises an acquisition module, a signal module, a processing module, a calculation module and a judgment module. According to the method, the technical problem of relay protection maloperation or operation refusal caused by high calculation complexity, weak anti-interference capability and insufficient adaptability of an existing saturation identification method is solved.

The invention provides a current transformer saturation detection method and system, and relates to the technical field of state detection and fault diagnosis of current transformers, and the method comprises the steps: synchronously collecting the secondary side current, bus voltage, cable insulation and partial discharge data of a current transformer, and carrying out the normalization according to classes, and then completing the time sequence alignment; secondly, a fixed sliding window is set, current distortion rate, voltage over-limit frequency, insulation parameter mean value and partial discharge pulse quantity characteristics are extracted, and whether current transformer saturation, insulation abnormity and partial discharge abnormity events exist in the window or not is judged according to the current distortion rate, the voltage over-limit frequency, the insulation parameter mean value and the partial discharge pulse quantity characteristics; counting the saturation probability under each node state based on a Bayesian causal network, calculating and normalizing the causal contribution degree of the insulation abnormity and the partial discharge abnormity to the saturation event, and determining a dominant influence factor; and finally, a health index is calculated in combination with the normalized contribution degree and the abnormal state, the running health condition of the current transformer is evaluated through trend analysis in combination with a dominant factor, saturation inducements are positioned, and misjudgment is avoided.

This invention discloses a current transformer saturation identification method, system, device, and medium. Specifically, it includes continuously acquiring phase voltage and current data of each phase on the secondary side of the protected line; determining whether protection should be activated based on the differential current; performing first-order differential processing on the secondary current to obtain a differential secondary current; normalizing the differential secondary current to obtain a normalized secondary current; extracting the phase of the normalized secondary current and constructing an ideal sinusoidal reference waveform with the same phase; calculating the fractal dimension of the phase trajectory of the normalized secondary current and the reference waveform respectively; and determining the saturation state of the current transformer based on the fractal dimension deviation. If the deviation is satisfied, the transformer is determined to be saturated; otherwise, it is determined to be unsaturated. The system includes an acquisition module, a signal module, a processing module, a calculation module, and a determination module. This invention solves the technical problems of relay protection maloperation or failure to operate caused by the high computational complexity, weak anti-interference ability, and insufficient adaptability of existing saturation identification methods.

The present application provides a method for determining a distance to a fault in a power systems network. The method may involve determining, based on a set of measured voltage samples, a set of processed voltage samples; determining, based on a set of measured current samples, a set of processed reactive current samples, a set of processed resistive current samples, a set of processed negative sequence current samples, and a set of processed zero sequence current samples; selecting, based on an indication from a faulty phase indicator, a selected processed voltage sample, a selected processed reactive current sample, a selected processed resistive current sample, and a selected processed negative or zero sequence current sample; determining, based on the selected processed reactive current sample, that no distortion has occurred due to current transformer (CT) saturation; and calculating, based on the determination that no distortion has occurred, the distance to the fault.

The invention discloses a current transformer adaptive compensation and protection strategy dynamic adjustment method and system, which can accurately identify the saturation state of a current transformer, adaptively calculate a compensation current capable of suppressing the current saturation of the current transformer according to the real-time saturation state of the current transformer, and meanwhile, automatically adjust the protection strategy of the current transformer. A reliable current data source is provided for an external protection device according to the saturation state of the current transformer, and a corresponding protection strategy adjustment instruction sent to the external protection device is dynamically adjusted; therefore, it is ensured that the CT can still keep high measurement precision under the large fault current, the reliability, selectivity and adaptive capacity of an external protection device are comprehensively improved, and the development requirements for safe, flexible and efficient operation of a power grid in the future are met.

The present disclosure relates to a method for controlling a differential protection system for a power system, the method comprising: sensing at least one first current through a first end of a power transmission line of the power system and at least one second current through a second end of the power transmission line; determining a first calculated current and a second calculated current based on the sensed at least one first current and the sensed at least one second current; determining at least one parameter based on the first calculated current and the second calculated current; determining a fault in the power transmission line based on the determined at least one parameter and / or the first calculated current and the second calculated current; and controlling the differential protection system based on the fault. The invention further relates to a corresponding device and system.

The application discloses a kind of transient stability analysis method and related device considering current limit, establish the mathematical model of hydropower system and photovoltaic power generation system;In view of the current-limiting control of photovoltaic inverter and flexible rectifier during fault, the equation of active power sent by hydro-generator before fault removal is derived according to Thevenin theorem;The analytical expression of critical removal angle of sending-out system is derived by using equal-area rule;With critical removal angle as the key index of transient stability limit of sending-out system, the influence of photovoltaic and flexible current transformer saturation current angle parameter value and water-light generation ratio on the transient stability of sending-out system is evaluated.The water-light generation ratio setting method involved in the application can effectively improve the transient stability of the system, and the research results are expected to provide certain theoretical guidance for the stable operation of future new energy power system.

The invention discloses a current transformer saturation identification method using a difference current cross-interval alternating characteristic. The method comprises the following steps: collecting current data; differential current is calculated, and whether differential protection is started or not is determined; calculating an accumulated difference charge quantity, and determining whether the accumulated difference charge quantity meets a linear region criterion; and detecting whether the differential current meets a saturation region criterion or not, and opening differential protection or locking. According to the current transformer saturation identification method based on the difference current cross-interval alternating characteristic, firstly, a traditional amplitude threshold value is replaced with integral quantization during difference charge quantity analysis, and the current transformer saturation recovery characteristic is better met; the sliding window integration can restrain high-frequency noise, and the integration process is equivalent to low-pass filtering; and thirdly, an alternating characteristic verification mechanism of linear region triggering and saturation region tracking is introduced, so that the problem of misoperation locking can be solved, timely locking protection can be carried out along with a saturation region after a linear region during external saturation, and misoperation locking can be avoided due to a non-saturation region after low current during internal faults.

The present disclosure relates to a method for controlling a differential protection system for an electrical power system, the method comprising: sensing at least one first current through a first end of a transmission line of the electrical power system and at least one second current through a second end of the transmission line; determining, based on the sensed at least one first current and the sensed at least one second current, a first computed current and a second computed current; determining, based on the first computed current and the second computed current, at least one parameter; determining, based on the determined at least one parameter and / or the first computed current and the second computed current, a fault in the electrical power transmission line; and controlling, based on the fault, the differential protection system. The present disclosure also relates to a respective device and system.

The present invention belongs to the field of electrical equipment detection, and solves the technical problem of being difficult to provide reliable electrical parameters when a current transformer is saturated. The present invention provides a current measurement method, a distribution transformer state detection method, and a protection method under the saturation of a current transformer. A state space model of the current transformer is established: a functional relationship between a state vector, an input vector, and an output vector is constructed, the state space model is rewritten in the form of a polyhedron, and a corresponding linear parameter varying observer LPV is designed to observe the state space model in the form of a polyhedron according to the input vector and the output vector, so as to obtain an estimated value of the state vector; the estimated value of the state vector is substituted into the magnetic flux equation of the primary current, and the estimated value of the primary current is calculated. By using the estimated value of the primary current measured by the present invention for state detection and fault protection of a distribution transformer, the reliability of the operation of the distribution transformer is improved.

The invention belongs to the technical field of current transformers, and particularly relates to a method for evaluating the anti-saturation performance of a P-level current transformer, which is used for evaluating the steady-state anti-saturation performance of the current transformer by using an error curve and a secondary load impedance measured value. Under the full-offset maximum short-circuit current, considering the C-O working cycle and the residual magnetism coefficient of the CT, and calculating a transient area coefficient so as to evaluate the transient anti-saturation performance of the current transformer; the anti-saturation performance of the current transformer is divided into four grades according to the calculation result of the steady-state and transient-state anti-saturation performance of the current transformer and the saturation detection function of the protection device, and the current transformer to be evaluated is classified into one grade. According to the method, four-stage evaluation of the anti-saturation performance is given, the problem that the transient saturation risk of the current transformer is uncertain on site is solved, scientific evaluation and suggestions are given for the saturation risk of the current transformer and possible hazards, and the operation safety of a power grid is improved.

This application provides a method for determining the distance to a fault in a power system network. The method may involve determining a set of processed voltage samples based on a set of measured voltage samples; determining a set of processed reactive current samples, a set of processed resistive current samples, a set of processed negative sequence current samples, and a set of processed zero sequence current samples based on a set of measured current samples; selecting selected processed voltage samples, selected processed reactive current samples, selected processed resistive current samples, and selected processed negative or zero sequence current samples based on an indication from a fault phase indicator; determining, based on the selected processed reactive current samples, that no distortion has occurred due to current transformer (CT) saturation; and calculating the distance to a fault based on the determination that no distortion has occurred.

Due to the fact that topological structures and control modes of a battery energy storage power station and a synchronous generator are obviously different, after the battery energy storage power station is connected, original fault current characteristics of a power transmission line of an electric power system are changed, traditional current differential protection has the risk of performance deterioration and even operation refusal, and safe and stable operation of the electric power system is seriously challenged. The invention discloses a battery energy storage power station AC tie line differential protection method based on a Ghost optimization multi-scale attention convolutional neural network, and the method comprises the steps: constructing a current track wrapping area image through collecting the current information of two sides of a line; and identifying a current track wrapping area image based on a multi-scale convolutional neural network improved by adopting a lightweight convolutional Ghost and a channel prior convolutional attention mechanism. The method is not influenced by access of a battery energy storage power station, internal and external faults can be accurately distinguished, and the method still has ideal effects under non-ideal conditions of current transformer saturation, current transformer measurement errors, noise and the like.

The invention discloses a current transformer saturation detection method, relates to the technical field of electromagnetic measurement, and solves the technical problems of weak interference resistance, single criterion and low steady-state saturation detection precision of transient saturation detection. A peak section is screened through voltage peak energy density, instantaneous noise is eliminated, the time synchronism of current abrupt change and voltage peak is verified through an abrupt change synchronism coefficient, and real saturation and independent interference are distinguished, so that the transient saturation misjudgment rate is reduced, the proportion of corrected characteristic harmonic waves is calculated, and inherent harmonic waves of a system are thoroughly deducted; the integration with attenuation calibration is adopted, the flux linkage calculation error is reduced, frequent manual calibration is not needed, the engineering practicability is improved, the waveform distortion stability coefficient is introduced, the standard deviation of the harmonic ratio in five cycles is quantified, short-time fluctuation misjudgment is avoided, and the steady-state saturation detection accuracy is improved.

The invention discloses a current transformer saturation detection method and system based on machine learning. The method comprises the following steps: generating CT saturation waveforms under different working conditions based on an electromagnetic transient simulation program of a power system; performing category labeling to obtain a labeled CT saturation waveform sample set; processing each sample waveform in the CT saturation waveform sample set, respectively extracting time domain features, frequency domain features and transient features, and constructing a multi-domain feature set; carrying out supervised learning training on the multi-domain feature set by adopting an improved gradient boosting tree model, and constructing a CT saturation detection classifier; obtaining to-be-detected current waveform data, and executing feature extraction operation to obtain to-be-detected multi-domain feature vectors; and inputting the to-be-detected multi-domain feature vector into the trained CT saturation detection classifier, and outputting a classification result and prediction confidence of the CT saturation degree. According to the method, automatic grading of the CT saturation state is realized, and the problems of low saturation efficiency and poor accuracy of a traditional identification method are effectively solved.

The invention discloses a zero-sequence inrush current protection method based on a digital primary and secondary fusion pole-mounted circuit breaker, and relates to the technical field of power system power distribution network protection. According to the method, in each task polling cycle, whether a subsequent process is started or not is judged according to zero-sequence voltage and zero-sequence current; analyzing the secondary harmonic content of the zero-sequence current in a plurality of continuous periods to obtain the dynamic change characteristics of the zero-sequence current, and adjusting an internal counter according to the dynamic change characteristics; and finally, whether zero-sequence overcurrent protection is locked or not is judged according to the numerical value of the counter, and the zero-sequence overcurrent protection is opened when a reset condition is met. According to the method, the zero-sequence inrush current and the grounding fault current generated by no-load closing of the transformer can be reliably distinguished, the problem of zero-sequence overcurrent protection maloperation or operation refusal caused by saturation of the current transformer is effectively solved, and the power supply reliability of the power distribution network is improved.

A method for determining a distance to a fault in a power system network is provided. The method may involve: determining a set of processed voltage samples based on a set of measured voltage samples; determining a set of processed reactive current samples, a set of processed resistive current samples, a set of processed negative sequence current samples, and a set of processed zero sequence current samples based on the set of measured current samples; selecting a selected processed voltage sample, a selected processed reactive current sample, a selected processed resistive current sample, and a selected processed negative or zero sequence current sample based on an indication from the faulty phase indicator; determining, based on the selected processed reactive current sample, that no distortion occurs due to current transformer (CT) saturation; and calculating a distance to the fault based on a determination that no distortion occurs.

A method for identifying inrush current and short-circuit current in transformer differential protection, the method comprising: taking the phase difference of differential current when the transformer simultaneously occurs short-circuit fault during inrush current as the phase difference ladder criterion of differential current under different conditions, and identifying inrush current and short-circuit current in the transformer according to the phase difference ladder criterion. The scheme can construct the phase difference ladder criterion of differential current under different conditions according to the characteristics of inrush current and short-circuit current, and realize accurate identification and distinction of inrush current and short-circuit current, ensuring the correctness of the operation of transformer differential protection.

This invention discloses a current transformer saturation identification method utilizing the alternating characteristics of differential current across different zones. The method includes: acquiring current data; calculating the differential current to determine whether differential protection should be activated; calculating the accumulated differential charge to determine whether the accumulated differential charge meets the linear zone criterion; detecting whether the differential current meets the saturation zone criterion, and opening or closing the differential protection. This current transformer saturation identification method utilizing the alternating characteristics of differential current across different zones has several advantages: first, it uses integral quantization instead of traditional amplitude thresholds in differential charge analysis, which better reflects the saturation recovery characteristics of current transformers; second, sliding window integration can suppress high-frequency noise, and its integration process is equivalent to low-pass filtering; and third, it introduces an alternating characteristic verification mechanism of linear zone triggering and saturation zone tracking, which can solve the problem of false blocking. This ensures timely blocking of protection when saturation occurs outside the zone because the linear zone is followed by a saturation zone, and avoids false blocking when there is no saturation zone after a fault within the zone due to low current.

The invention discloses an active power measurement method and system for a generator control system, a medium and equipment, and belongs to the technical field of electric power engineering.The method comprises the steps that a power output value is calculated through a power measurement instrument according to collected three-phase voltage and current waveform data; monitoring the harmonic content and the negative sequence voltage in the three-phase current, and judging the CT saturation condition of the current transformer: if the CT is saturated, correcting the distorted waveform based on the trained LSTM waveform correction model, and outputting a power correction value according to the corrected waveform; and if the current transformer CT is not saturated, outputting a power output value. According to the invention, the problem of power error adjustment caused by serious distortion of a power measurement signal due to saturation of a measurement-level CT iron core of the generator is solved.