Reactor turn-to-turn fault protection method and system for tracking voltage and current change trend

Abstract

The invention discloses an electric reactor turn-to-turn fault protection method and system for tracking the voltage and current change trend, and relates to the technical field of power system relay protection, and the method comprises the steps: collecting voltage sampling point data and current sampling point data of an electric reactor protection device side based on a preset frequency; calculating a positive sequence voltage effective value, a three-phase current effective value, a positive sequence current effective value and a negative sequence current effective value based on the voltage sampling point data and the current sampling point data; judging whether turn-to-turn protection starting conditions, turn-to-turn protection action conditions and turn-to-turn protection current change trend conditions are met or not; and if the turn-to-turn protection starting condition, the turn-to-turn protection action condition and the turn-to-turn protection current change trend condition are all satisfied within the preset sampling time, controlling the reactor protection device to act. According to the invention, the technical problem that the reactor may be damaged due to slow action of a relay protection device during turn-to-turn fault of the 35kV reactor in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection in power systems, and specifically provides a method and system for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current. Background Art

[0002] The 35kV reactor is an important device in the 35KV power system, mainly used for regulating current, limiting short-circuit faults, suppressing harmonics, and improving the stability of the power system. This device has a wide range of applications in the power system. With the long-term operation or overload of the reactor, the winding insulation materials (such as epoxy resin and paper insulation) age or deteriorate, and the reactor equipment may cause inter-turn protection faults. During the inter-turn fault of the reactor, the fault current gradually increases, the wire temperature gradually rises, igniting the insulation material, and ultimately causing the reactor to catch fire and burn out.

[0003] At present, the inter-turn faults of reactors mostly use the zero-sequence impedance principle to achieve. However, the 35kV power system uses an ungrounded system, so the inter-turn protection of reactors based on the zero-sequence impedance principle is not applicable to 35kV reactors; in addition, 35kV reactors usually use overcurrent protection to achieve inter-turn fault tripping. However, when the overcurrent protection operates with a time delay, this time delay is set in milliseconds. During this period, a slight inter-turn fault of the reactor may develop into a serious fault, and the overcurrent protection fails to isolate the fault in time and protect the primary equipment. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current in order to solve at least one of the above technical problems.

[0005] In a first aspect, an embodiment of the present invention provides a method for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current, which is applied to a reactor protection device in a 35kV power system; the method includes: collecting voltage sampling point data and current sampling point data on the side of the reactor protection device based on a preset frequency; calculating the positive-sequence voltage effective value, three-phase current effective value, positive-sequence current effective value, and negative-sequence current effective value based on the voltage sampling point data and the current sampling point data; judging whether the inter-turn protection starting condition is satisfied based on the ratios of the positive-sequence voltage effective value, the three-phase current effective value, the negative-sequence current effective value to the positive-sequence current effective value; judging whether the inter-turn protection action condition is satisfied based on the changing trend of the positive-sequence voltage effective value; judging whether the inter-turn protection current changing trend condition is satisfied based on the three-phase current effective value, the negative-sequence current effective value, the positive-sequence current effective value, and the ratios of the negative-sequence current effective value to the positive-sequence current effective value; if the inter-turn protection starting condition, the inter-turn protection action condition, and the inter-turn protection current changing trend condition are all satisfied within a preset sampling time, then controlling the reactor protection device to act.

[0006] Further, based on the voltage sampling point data and the current sampling point data, calculating the positive sequence voltage effective value, the three-phase current effective value, the positive sequence current effective value, and the negative sequence current effective value, includes: converting the voltage sampling point data and the current sampling point data into voltage vector data and current vector data respectively through the full-cycle Fourier algorithm; calculating the positive sequence voltage effective value, the three-phase current effective value, the positive sequence current effective value, and the negative sequence current effective value based on the voltage vector data and the current vector data.

[0007] Further, the inter-turn protection startup conditions include a positive sequence voltage condition, a three-phase current condition, and a ratio condition; wherein, the positive sequence voltage condition includes: the positive sequence voltage effective value is greater than a first preset voltage threshold; the three-phase current condition includes: the three-phase current effective values are all greater than a preset no-load current threshold; the ratio condition includes: the ratio of the negative sequence current effective value to the positive sequence current effective value is greater than a preset sensitivity coefficient.

[0008] Further, based on the positive sequence voltage effective value, the three-phase current effective value, and the ratio of the negative sequence current effective value to the positive sequence current effective value, determining whether the inter-turn protection startup conditions are satisfied, includes: based on the positive sequence voltage effective value, the three-phase current effective value, and the ratio of the negative sequence current effective value to the positive sequence current effective value, determining whether the positive sequence voltage condition, the three-phase current condition, and the ratio condition are all satisfied; if so, it is determined that the inter-turn protection startup conditions are satisfied.

[0009] Further, based on the change trend of the positive sequence voltage effective value, determining whether the inter-turn protection operation conditions are satisfied, includes: determining whether the absolute value of the difference between the positive sequence voltage effective value corresponding to the current cycle and the positive sequence voltage effective value corresponding to the historical cycle is less than a second preset voltage threshold; if so, it is determined that the inter-turn protection operation conditions are satisfied.

[0010] Further, the inter-turn protection current change trend conditions include a phase current change trend condition, a negative sequence current change trend condition, a positive sequence current change trend condition, and a ratio change trend condition; wherein, the phase current change trend condition includes: the change trend of at least one of the three-phase current effective values is an increasing trend; the negative sequence current change trend condition includes: the change trend of the negative sequence current effective value is an increasing trend; the positive sequence current change trend condition includes: the change trend of the positive sequence current effective value is an increasing trend; the ratio change trend condition includes: the change trend of the ratio of the negative sequence current effective value to the positive sequence current effective value is an increasing trend.

[0011] Further, based on the effective values of the three-phase current, the effective value of the negative-sequence current, the effective value of the positive-sequence current, and the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current, it is determined whether the condition of the variation trend of the inter-turn protection current is satisfied, including: based on the effective values of the three-phase current, the effective value of the negative-sequence current, the effective value of the positive-sequence current, and the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current, it is determined whether the phase current variation trend condition, the negative-sequence current variation trend condition, the positive-sequence current variation trend condition, and the ratio variation trend condition are all satisfied; if so, it is determined that the condition of the variation trend of the inter-turn protection current is satisfied.

[0012] In a second aspect, an inter-turn fault protection system for a reactor that tracks the variation trends of voltage and current provided by an embodiment of the present invention is applied to a reactor protection device of a 35 kV power system; it includes: a sampling module, a calculation module, a first judgment module, a second judgment module, a third judgment module, and a protection module; wherein, the sampling module is configured to collect voltage sampling point data and current sampling point data on the side of the reactor protection device based on a preset frequency; the calculation module is configured to calculate the effective value of the positive-sequence voltage, the effective values of the three-phase current, the effective value of the positive-sequence current, and the effective value of the negative-sequence current based on the voltage sampling point data and the current sampling point data; the first judgment module is configured to determine whether the inter-turn protection startup condition is satisfied based on the effective value of the positive-sequence voltage, the effective values of the three-phase current, and the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current; the second judgment module is configured to determine whether the inter-turn protection action condition is satisfied based on the variation trend of the effective value of the positive-sequence voltage; the third judgment module is configured to determine whether the condition of the variation trend of the inter-turn protection current is satisfied based on the effective values of the three-phase current, the effective value of the negative-sequence current, the effective value of the positive-sequence current, and the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current; the protection module is configured to control the reactor protection device to act if the inter-turn protection startup condition, the inter-turn protection action condition, and the condition of the variation trend of the inter-turn protection current are all satisfied within a preset sampling time.

[0013] In a third aspect, an electronic device provided by an embodiment of the present invention includes: a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the computer program, the method provided by the embodiment of the present invention is implemented.

[0014] In a fourth aspect, a computer-readable storage medium provided by an embodiment of the present invention stores computer instructions, and when the computer instructions are executed by a processor, the method provided by the embodiment of the present invention is implemented.

[0015] The present invention provides a method and system for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current, which can improve the action delay of the 35 kV reactor inter-turn fault from the order of hundreds of milliseconds to the order of ten milliseconds, effectively reduce the duration of the reactor inter-turn fault, avoid the risk of the reactor catching fire and burning out, and extend the service life of the reactor equipment. The judgment process uses the sensitive starting coefficient of the ratio of negative-sequence current to positive-sequence current, which can effectively judge the slight inter-turn protection fault. At the same time, the discrimination of tracking the changing trends of positive-sequence voltage and current is adopted, which can effectively and quickly identify the 35 kV reactor inter-turn fault and improve the sensitivity of the reactor protection. The present invention alleviates the technical problem in the prior art that when a 35 kV reactor has an inter-turn fault, the relay protection device acts slowly, resulting in the possible damage of the reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the specific embodiments or the description of the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a flowchart of a method for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of a system for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0019] Embodiment 1

[0020] Figure 1 It is a flowchart of a method for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current provided by an embodiment of the present invention. This method is applied to the reactor protection device in a 35 kV power system. As Figure 1 shown, the method specifically includes the following steps: Step S102: Collect the voltage sampling point data and current sampling point data on the side of the reactor protection device based on a preset frequency.

[0021] Step S104: Calculate the positive-sequence voltage effective value, three-phase current effective values, positive-sequence current effective value, and negative-sequence current effective value based on the voltage sampling point data and current sampling point data.

[0022] Step S106: Determine whether the turn-to-turn protection startup condition is satisfied based on the ratio of the positive-sequence voltage effective value, three-phase current effective values, and negative-sequence current effective value to the positive-sequence current effective value.

[0023] Step S108: Determine whether the turn-to-turn protection action condition is satisfied based on the changing trend of the positive-sequence voltage effective value.

[0024] Step S110: Determine whether the turn-to-turn protection current changing trend condition is satisfied based on the three-phase current effective values, negative-sequence current effective value, positive-sequence current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value.

[0025] Step S112: If the turn-to-turn protection startup condition, turn-to-turn protection action condition, and turn-to-turn protection current changing trend condition are all satisfied within the preset sampling time, then control the reactor protection device to act.

[0026] Specifically, step S104 further includes the following steps: Step S1041: Convert the voltage sampling point data and current sampling point data into voltage vector data and current vector data respectively through the full-cycle Fourier algorithm; Step S1042: Calculate the positive-sequence voltage effective value, three-phase current effective values, positive-sequence current effective value, and negative-sequence current effective value based on the voltage vector data and current vector data.

[0027] Specifically, the full-cycle wave vector value expression:

[0028] Among them, represents the full-cycle wave vector value, is the real part of the vector value, i represents the imaginary unit, and its calculation formula is as follows:

[0029] Im is the imaginary part of the vector value, and its calculation formula is as follows:

[0030] The calculation formula for the vector value effective value is as follows:

[0031] In the above formulas (2) and (3): is the sampling point array, j represents the sampling point array number, N represents the number of sampling points in a cycle, and the subsequent N definitions are the same.

[0032] Optionally, N = 24, that is, the number of points corresponding to one - cycle sampling points is 24.

[0033] Through formulas (1) to (3) and the voltage sampling point data and the current sampling point data , the voltage vector data and the current vector data are calculated respectively. Among them, is the phase type, including phase a, phase b or phase c.

[0034] Then, the positive - sequence voltage vector value , the positive - sequence current vector value and the negative - sequence current vector value are calculated through formulas (4), (5) and (6):

[0035]

[0036]

[0037] Through the above vector value calculation, the positive - sequence voltage vector value , the positive - sequence current vector value , the negative - sequence current vector value and the three - phase current vector value required by the present invention are obtained.

[0038] The effective values corresponding to each voltage vector value and current vector value are calculated through formula (4): Calculate the positive - sequence voltage effective value and record it into the positive - sequence voltage array corresponding to the current sampling point n , the positive - sequence current effective value and record it into the positive - sequence current array corresponding to the current sampling point n , the negative - sequence current effective value and record it into the negative - sequence current array corresponding to the current sampling point n , the three - phase current effective value and record it into the positive - sequence current array corresponding to the current sampling point n , the ratio of the negative - sequence current effective value to the positive - sequence current effective value .

[0039] Specifically, the inter - turn protection starting conditions include positive - sequence voltage conditions, three - phase current conditions and ratio conditions; among them, (1) The positive - sequence voltage conditions include: the positive - sequence voltage effective value is greater than the first preset voltage threshold. For example, if the first preset voltage threshold is 0.95 times the rated voltage, the discriminant formula for the positive - sequence voltage condition is as follows: The current positive - sequence voltage effective value Greater than 0.95 times the rated voltage 。

[0040] (2) The three-phase current conditions include: the effective values of the three-phase currents are all greater than a preset no-current threshold value. Specifically, the discriminant is as follows: The current effective values of the three-phase phase currents are all greater than a preset no-current threshold value (For example, the preset no-current threshold value is 0.04 times the rated current): 。

[0041] (3) The ratio condition includes: the ratio of the negative-sequence current effective value to the positive-sequence current effective value is greater than a preset sensitivity coefficient. Specifically, the discriminant is as follows: Negative-sequence current effective value and the positive-sequence current effective value ratio is greater than a preset sensitivity coefficient (For example, take a value between 0.05 and 0.1): 。

[0042] The sensitivity coefficient value is directly related to the severity of the turn-to-turn fault. The turn-to-turn fault of the reactor develops from a slight turn-to-turn fault to a severe turn-to-turn fault. When the value is smaller, the turn-to-turn fault can be detected earlier during the development from a slight to a severe turn-to-turn fault. In the embodiments of the present invention, to ensure the sensitivity of the turn-to-turn fault recognition, the value is taken as 0.05, so that it can be started in time during the development of the turn-to-turn slight fault to the moderate fault, ensuring the sensitivity of the turn-to-turn protection.

[0043] That is, the ratio condition is 。

[0044] Specifically, step S106 includes: Based on the positive-sequence voltage effective value, the three-phase current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value, determine whether the positive-sequence voltage condition, the three-phase current condition, and the ratio condition are all satisfied; If so, it is determined that the turn-to-turn protection start condition is satisfied.

[0045] Specifically, the discriminant of the turn-to-turn protection start condition is as follows:

[0046] If the discriminant is satisfied, the turn-to-turn protection start condition is satisfied; otherwise, the turn-to-turn protection action delay is set to 0.

[0047] Specifically, step S108 includes the following steps: Determine whether the absolute value of the difference between the positive-sequence voltage effective value corresponding to the current cycle and the positive-sequence voltage effective value corresponding to the historical cycle is less than the second preset voltage threshold; optionally, the historical cycle is the cycle m cycles before the current cycle. If so, it is determined that the condition for the turn-to-turn protection action is satisfied.

[0048] Optionally, the second preset voltage threshold is 0.02 times the rated voltage value Un.

[0049] Specifically, there is a period of time from when a turn-to-turn fault occurs in the 35kV reactor to when the reactor burns out. This time is at least several hundred milliseconds. During these several hundred milliseconds, the voltage of the reactor remains basically unchanged and maintains at the level of the system voltage until the voltage drops to 0V when the reactor burns out. According to the voltage characteristics of the turn-to-turn fault, the positive-sequence voltage of the reactor is tracked and judged. The judgment conditions are as follows: Current positive-sequence voltage effective value And the positive-sequence voltage effective value m cycles ago The absolute value of the difference is less than :

[0050] For example, the current sampling point count n of the reactor protection device is 36, m cycles take 1 cycle, and the sampling point count corresponding to 1 cycle ago is , that is, the current positive-sequence voltage effective value discrimination formula is as follows:

[0051] When the positive-sequence voltage effective value corresponding to the sampling point count of 36 satisfies the above formula, it is considered that the positive-sequence voltage has not changed, and the positive-sequence voltage change trend of the turn-to-turn fault with the sampling point count of 36 satisfies the condition for the turn-to-turn protection action. Otherwise, it is considered that the positive-sequence voltage action condition of the turn-to-turn fault is not satisfied, and the turn-to-turn fault protection action delay is set to 0.

[0052] Specifically, the turn-to-turn protection current change trend conditions include phase current change trend conditions, negative-sequence current change trend conditions, positive-sequence current change trend conditions, and ratio change trend conditions; among them, (1) The phase current change trend conditions include: the change trend of at least one of the three-phase current effective values in the three-phase current effective values is an increasing trend.

[0053] There is a period of time from when a turn-to-turn fault occurs in the 35kV reactor to when the reactor burns out. This time is at least several hundred milliseconds. During these several hundred milliseconds, the phase current of the reactor slowly increases. According to the current characteristics of the turn-to-turn fault, the phase current of the reactor is tracked and judged.

[0054] Current phase current effective value And the corresponding phase current effective value m cycles ago The difference is greater than times the effective value of the phase current corresponding to m cycles ago :

[0055] For example, the current sampling point count n of the reactor protection device is 36, m cycles take 1 cycle, and the sampling point count corresponding to 1 cycle ago is , to meet the sufficient sensitivity for inter-turn faults, then takes a value of 0.05, that is, the discrimination formula for the phase current change trend condition is as follows:

[0056] Taking the occurrence of an inter-turn fault between phases a and b as an example, when the effective value of the phase current of phase a or phase b at the sampling point count of 36 satisfies the above formula, it is considered that the phase current change trend at the sampling point count of 36 meets the phase current change trend condition.

[0057] (2) The negative-sequence current change trend condition includes: the change trend of the negative-sequence current effective value is an increasing trend.

[0058] Specifically, there will be a period of time from the occurrence of an inter-turn fault in the 35kV reactor to the burnout of the reactor. This time is at least several hundred milliseconds. During these several hundred milliseconds, the negative-sequence current of the reactor slowly increases. According to the negative-sequence current characteristics of the inter-turn fault, the negative-sequence current of the reactor is tracked and judged.

[0059] The judgment conditions are as follows: The current negative-sequence current effective value and the negative-sequence current effective value corresponding to m cycles ago The difference is greater than times the negative-sequence current effective value corresponding to m cycles ago :

[0060] For example, the current sampling point count n of the reactor protection device is 36, m cycles take 1 cycle, and the sampling point count corresponding to 1 cycle ago is , to meet the sufficient sensitivity for inter-turn faults, then takes a value of 0.02, that is, the discrimination formula for the negative-sequence current change trend condition is as follows:

[0061] Taking the occurrence of an inter-turn fault between phases a and b as an example, when the negative-sequence current effective value at the sampling point count of 36 satisfies the above formula, it is considered that the negative-sequence current change trend at the sampling point count of 36 meets the negative-sequence current change trend condition.

[0062] (3) The condition of the positive-sequence current change trend includes: the change trend of the effective value of the positive-sequence current is an increasing trend.

[0063] Specifically, there is a period of time from when an inter-turn fault occurs in the 35 kV reactor to when the reactor burns out. This time is at least several hundred milliseconds. During these several hundred milliseconds, the positive-sequence current of the reactor slowly increases. According to the positive-sequence current characteristics of the inter-turn fault, the positive-sequence current of the reactor is tracked and judged.

[0064] Its judgment condition is as follows: The current effective value of the positive-sequence current and the effective value of the positive-sequence current corresponding to m cycles ago The difference is greater than times the effective value of the positive-sequence current corresponding to m cycles ago ;

[0065] For example, the current sampling point count n of the reactor protection device is 36, and m cycles take 1 cycle. The sampling point count corresponding to 1 cycle ago is , to meet the sufficient sensitivity for the inter-turn fault, then is taken as 0.05, that is, the discrimination formula for the positive-sequence current change trend condition is as follows:

[0066] Taking the occurrence of an inter-turn fault between phases a and b as an example, when the effective value of the positive-sequence current at the sampling point count of 36 satisfies the above formula, it is considered that the change trend of the positive-sequence current at the sampling point count of 36 meets the positive-sequence current change trend condition.

[0067] (4) The condition of the ratio change trend includes: the change trend of the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current is an increasing trend.

[0068] Specifically, there is a period of time from when an inter-turn fault occurs in the 35 kV reactor to when the reactor burns out. This time is at least several hundred milliseconds. During these several hundred milliseconds, the ratio of the negative-sequence current and the positive-sequence current of the reactor slowly increases. According to the ratio of the negative-sequence current and the positive-sequence current of the inter-turn fault

[0069] Its judgment condition is as follows: The current ratio of the effective value of the negative-sequence current and the effective value of the positive-sequence current and the ratio of the effective value of the negative-sequence current and the effective value of the positive-sequence current corresponding to m cycles ago The difference is greater than :

[0070] For example, the current sampling point count n of the reactor protection device is 36, and 1 cycle is taken from m cycles. The sampling point count corresponding to 1 cycle before is . To meet the sufficient sensitivity for inter-turn faults, then The value is taken as 0.01, that is, the discrimination formula for the ratio change trend condition is as follows:

[0071] Taking the occurrence of an inter-turn fault between phases a and b as an example, when the ratio of the rms value of the negative-sequence current to the rms value of the positive-sequence current at the sampling point count of 36 meets the above formula, then it is considered that the ratio of the rms value of the negative-sequence current to the rms value of the positive-sequence current at the sampling point count of 36 has a change trend that meets the ratio change trend condition.

[0072] Specifically, step S110 includes the following steps: Based on the rms values of the three-phase currents, the rms value of the negative-sequence current, the rms value of the positive-sequence current, and the ratio of the rms value of the negative-sequence current to the rms value of the positive-sequence current, judge whether the phase current change trend condition, the negative-sequence current change trend condition, the positive-sequence current change trend condition, and the ratio change trend condition are all satisfied; If so, it is determined that the inter-turn protection current change trend condition is satisfied.

[0073] Specifically, step S112 includes: when the inter-turn protection startup condition is satisfied, the inter-turn protection action condition is satisfied, and the inter-turn protection current change trend condition is satisfied at the same sampling moment, then the target inter-turn protection action condition at this sampling point is satisfied. When the target inter-turn protection action conditions for the sampling points corresponding to consecutive M milliseconds are all satisfied, the inter-turn protection acts and trips.

[0074] Taking the occurrence of an inter-turn fault between phases a and b as an example, when the above-mentioned target inter-turn protection action condition is satisfied at the sampling point count of 36, the timing judgment starts.

[0075] From the sampling point count of 36 onwards, the sampling points corresponding to M milliseconds all satisfy the target inter-turn protection action condition, that is, the positive-sequence voltage remains basically unchanged within M milliseconds, the current of phase a or phase b continues to increase, the negative-sequence current continues to increase, the positive-sequence current continues to increase, and the ratio of the negative-sequence current to the positive-sequence current also continues to increase, then the inter-turn protection acts.

[0076] Optionally, in this example, M milliseconds is taken as 2 times the cycle time (1 cycle is 20 ms, and the corresponding sampling point count N is 24 points), that is, from the sampling point count of 36 to the count of 84 (36 + 48), if each point satisfies the target inter-turn protection action condition, then the inter-turn protection trips.

[0077] As can be seen from the above description, the embodiment of the present invention provides a method for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current. Using a reactor protection device, the three-phase voltages and three-phase currents connected to the reactor are collected; and the corresponding positive-sequence voltage, three-phase current, positive-sequence current, and negative-sequence current are calculated, and judgments are made according to the characteristics of the 35kV reactor inter-turn faults: According to the voltage characteristics of the 35kV reactor inter-turn faults, the following discrimination is made: When an inter-turn fault occurs, the positive-sequence voltage changes little. By tracking the trend that the positive-sequence voltage remains basically unchanged, it is judged whether an inter-turn fault occurs in the reactor. If the positive-sequence voltage remains basically unchanged, it is considered that an inter-turn fault may occur in the reactor, and then further judgment is made on the current to accelerate the action of the inter-turn protection; According to the current characteristics of the 35kV reactor inter-turn faults, the following discrimination is made: When an inter-turn fault occurs, the phase current, positive-sequence current, and negative-sequence current all increase slowly. By tracking the trend that the ratios of the phase current, negative-sequence current, positive-sequence current, and negative-sequence current to the positive-sequence current all continue to increase, it is considered that the current meets the characteristics of the inter-turn fault. When both the voltage characteristics and the current characteristics are met, the inter-turn fault protection trips. The present invention can quickly and accurately judge the inter-turn faults of the 35kV reactor and shorten the inter-turn fault removal time.

[0078] Embodiment 2

[0079] Figure 2 is a schematic diagram of a system for protecting the inter-turn faults of a reactor by tracking the changing trends of voltage and current according to the embodiment of the present invention. This system is applied to the reactor protection device of a 35kV power system. As Figure 2 shown, this system includes: a sampling module 10, a calculation module 20, a first judgment module 30, a second judgment module 40, a third judgment module 50, and a protection module 60.

[0080] Specifically, the sampling module 10 is used to collect voltage sampling point data and current sampling point data on the side of the reactor protection device based on a preset frequency.

[0081] The calculation module 20 is used to calculate the effective value of the positive-sequence voltage, the effective values of the three-phase currents, the effective value of the positive-sequence current, and the effective value of the negative-sequence current based on the voltage sampling point data and the current sampling point data.

[0082] The first judgment module 30 is used to judge whether the starting conditions for the inter-turn protection are met based on the ratios of the effective value of the positive-sequence voltage, the effective values of the three-phase currents, and the effective value of the negative-sequence current to the effective value of the positive-sequence current.

[0083] The second judgment module 40 is used to judge whether the action conditions for the inter-turn protection are met based on the changing trend of the effective value of the positive-sequence voltage.

[0084] The third determination module 50 is configured to determine whether the inter-turn protection current change trend condition is satisfied based on the effective values of the three-phase current, the effective value of the negative-sequence current, the effective value of the positive-sequence current, and the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current.

[0085] The protection module 60 is configured to control the reactor protection device to act if the inter-turn protection startup condition, the inter-turn protection action condition, and the inter-turn protection current change trend condition are all satisfied within a preset sampling time.

[0086] Specifically, the calculation module 20 is further configured to: convert the voltage sampling point data and the current sampling point data into voltage vector data and current vector data respectively through the full-cycle Fourier algorithm; calculate the effective value of the positive-sequence voltage, the effective values of the three-phase current, the effective value of the positive-sequence current, and the effective value of the negative-sequence current based on the voltage vector data and the current vector data.

[0087] Specifically, the inter-turn protection startup condition includes a positive-sequence voltage condition, a three-phase current condition, and a ratio condition; wherein, the positive-sequence voltage condition includes: the effective value of the positive-sequence voltage is greater than a first preset voltage threshold; the three-phase current condition includes: the effective values of the three-phase current are all greater than a preset no-current threshold; the ratio condition includes: the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current is greater than a preset sensitivity coefficient.

[0088] Specifically, the first determination module 30 is further configured to: determine whether the positive-sequence voltage condition, the three-phase current condition, and the ratio condition are all satisfied based on the effective value of the positive-sequence voltage, the effective values of the three-phase current, and the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current; if so, determine that the inter-turn protection startup condition is satisfied.

[0089] Specifically, the second determination module 40 is further configured to: determine whether the absolute value of the difference between the effective value of the positive-sequence voltage corresponding to the current cycle and the effective value of the positive-sequence voltage corresponding to the historical cycle is less than a second preset voltage threshold; if so, determine that the inter-turn protection action condition is satisfied.

[0090] Specifically, the inter-turn protection current change trend condition includes a phase current change trend condition, a negative-sequence current change trend condition, a positive-sequence current change trend condition, and a ratio change trend condition; wherein, the phase current change trend condition includes: the change trend of at least one of the effective values of the three-phase current is an increasing trend; the negative-sequence current change trend condition includes: the change trend of the effective value of the negative-sequence current is an increasing trend; the positive-sequence current change trend condition includes: the change trend of the effective value of the positive-sequence current is an increasing trend; the ratio change trend condition includes: the change trend of the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current is an increasing trend.

[0091] Specifically, the third determination module 50 is further configured to: based on the effective values of the three-phase current, the effective value of the negative-sequence current, the effective value of the positive-sequence current, and the ratio of the effective value of the negative-sequence current to the effective value of the positive-sequence current, determine whether the phase current change trend condition, the negative-sequence current change trend condition, the positive-sequence current change trend condition, and the ratio change trend condition are all satisfied; if so, determine that the turn-to-turn protection current change trend condition is satisfied.

[0092] The present invention also provides an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor implements the method provided by the embodiment of the present invention when executing the computer program.

[0093] The present invention also provides a computer-readable storage medium, where the computer-readable storage medium stores computer instructions, and the computer instructions implement the method provided by the embodiment of the present invention when executed by a processor.

[0094] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0095] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A protection method for inter-turn faults of a reactor that tracks the changing trends of voltage and current, characterized in that, Reactor protection device applied to 35 kV power system; The method includes: Collect voltage sampling point data and current sampling point data on the side of the reactor protection device based on a preset frequency; Calculate the positive-sequence voltage effective value, three-phase current effective value, positive-sequence current effective value, and negative-sequence current effective value based on the voltage sampling point data and the current sampling point data; Judge whether the inter-turn protection starting condition is satisfied based on the ratio of the positive-sequence voltage effective value, the three-phase current effective value, the negative-sequence current effective value to the positive-sequence current effective value; Judge whether the inter-turn protection action condition is satisfied based on the change trend of the positive-sequence voltage effective value; Judge whether the inter-turn protection current change trend condition is satisfied based on the three-phase current effective value, the negative-sequence current effective value, the positive-sequence current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value; If the inter-turn protection starting condition, the inter-turn protection action condition, and the inter-turn protection current change trend condition are all satisfied within a preset sampling time, then control the reactor protection device to act.

2. The method according to claim 1, wherein: Calculating the positive-sequence voltage effective value, the three-phase current effective value, the positive-sequence current effective value, and the negative-sequence current effective value based on the voltage sampling point data and the current sampling point data includes: Convert the voltage sampling point data and the current sampling point data into voltage vector data and current vector data respectively through the full-cycle Fourier algorithm; Calculate the positive-sequence voltage effective value, the three-phase current effective value, the positive-sequence current effective value, and the negative-sequence current effective value based on the voltage vector data and the current vector data.

3. The method according to claim 1, wherein: The inter-turn protection starting condition includes a positive-sequence voltage condition, a three-phase current condition, and a ratio condition; where The positive-sequence voltage condition includes: the positive-sequence voltage effective value is greater than a first preset voltage threshold; The three-phase current condition includes: the three-phase current effective values are all greater than a preset no-current threshold; The ratio condition includes: the ratio of the negative-sequence current effective value to the positive-sequence current effective value is greater than a preset sensitivity coefficient.

4. The method according to claim 3, wherein: Judging whether the inter-turn protection starting condition is satisfied based on the positive-sequence voltage effective value, the three-phase current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value includes: Judge whether the positive-sequence voltage condition, the three-phase current condition, and the ratio condition are all satisfied based on the positive-sequence voltage effective value, the three-phase current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value; If so, it is determined that the inter-turn protection starting condition is satisfied.

5. The method according to claim 1, characterized in that: Judging whether the inter-turn protection action condition is satisfied based on the change trend of the positive-sequence voltage effective value includes: Judge whether the absolute value of the difference between the positive-sequence voltage effective value corresponding to the current cycle and the positive-sequence voltage effective value corresponding to the historical cycle is less than a second preset voltage threshold; If so, it is determined that the inter-turn protection action condition is satisfied.

6. The method according to claim 1, wherein: The inter-turn protection current change trend condition includes a phase current change trend condition, a negative-sequence current change trend condition, a positive-sequence current change trend condition, and a ratio change trend condition; where The phase current change trend condition includes: the change trend of at least one of the three-phase current effective values is an increasing trend; The negative-sequence current change trend condition includes: the change trend of the negative-sequence current effective value is an increasing trend; The positive-sequence current change trend condition includes: the change trend of the positive-sequence current effective value is an increasing trend; The ratio change trend condition includes: the change trend of the ratio of the negative-sequence current effective value to the positive-sequence current effective value is an increasing trend.

7. The method according to claim 6, characterized in that: Based on the three-phase current effective values, the negative-sequence current effective value, the positive-sequence current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value, determining whether the turn-to-turn protection current change trend condition is satisfied includes: Based on the three-phase current effective values, the negative-sequence current effective value, the positive-sequence current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value, determining whether the phase current change trend condition, the negative-sequence current change trend condition, the positive-sequence current change trend condition, and the ratio change trend condition are all satisfied; If so, it is determined that the turn-to-turn protection current change trend condition is satisfied.

8. A reactor turn-to-turn fault protection system for tracking the change trend of voltage and current, characterized in that, A reactor protection device applied to a 35 kV power system; includes: a sampling module, a calculation module, a first judgment module, a second judgment module, a third judgment module, and a protection module; wherein, The sampling module is used to collect voltage sampling point data and current sampling point data on the side of the reactor protection device based on a preset frequency; The calculation module is used to calculate the positive-sequence voltage effective value, the three-phase current effective value, the positive-sequence current effective value, and the negative-sequence current effective value based on the voltage sampling point data and the current sampling point data; The first judgment module is used to judge whether the turn-to-turn protection starting condition is satisfied based on the positive-sequence voltage effective value, the three-phase current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value; The second judgment module is used to judge whether the turn-to-turn protection action condition is satisfied based on the change trend of the positive-sequence voltage effective value; The third judgment module is used to judge whether the turn-to-turn protection current change trend condition is satisfied based on the three-phase current effective values, the negative-sequence current effective value, the positive-sequence current effective value, and the ratio of the negative-sequence current effective value to the positive-sequence current effective value; The protection module is used to control the reactor protection device to act if the turn-to-turn protection starting condition, the turn-to-turn protection action condition, and the turn-to-turn protection current change trend condition are all satisfied within a preset sampling time.

9. An electronic device, characterized in that, Includes: A memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the computer program, the method described in any one of claims 1-7 is implemented.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions, and when the computer instructions are executed by the processor, the method described in any one of claims 1-7 is implemented.

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